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Ibáñez P, Villa-Abaunza A, Udías JM. Impact on the estimated dose of different tissue assignment strategies during partial breast irradiations with INTRABEAM. Brachytherapy 2024:S1538-4721(24)00034-5. [PMID: 38705803 DOI: 10.1016/j.brachy.2024.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/19/2024] [Accepted: 02/12/2024] [Indexed: 05/07/2024]
Abstract
PURPOSE Partial breast irradiations with electronic brachytherapy or kilovoltage intraoperative radiotherapy devices such as Axxent or INTRABEAM are becoming more common every day. Breast is mainly composed of glandular and adipose tissues, which are not always clearly disentangled in planning breast CTs. In these cases, breast tissues are replaced with an average soft tissue, or even water. However, at kilovoltage energies, this may lead to large differences in the delivered dose, due to the dominance of photoelectric effect. Therefore, the aim of this work was to study the effect on the dose prescribed in breast with the INTRABEAM device using different soft tissue assignment strategies that would replace the adipose and glandular tissues that constitute the breast in cases where these tissues cannot be adequately distinguished in a CT scan. METHODS AND MATERIALS Dose was computed with a Monte Carlo code in five patients with a 3 cm diameter INTRABEAM spherical applicator. Tissues within the breast were assigned following six different strategies: one based on the TG-43 recommendations, representing the whole breast as water of unity density, another one also water-based but with CT derived density, and the other four also based on CT-derived densities, using a single tissue resulting from different mixes of glandular and adipose tissues. These were compared against the reference dose computed in an accurately segmented CT, following TG-186 recommendations. Relative differences and dose ratios between the reference and the other tissue assignment strategies were obtained in three regions of interest inside the breast. RESULTS AND CONCLUSIONS Dose planning in water-based tissues was found inaccurate for breast treatment with INTRABEAM, as it would incur in up to 30% under-prescription of dose. If accurate soft tissue assignments in the breast cannot be safely done, a single-tissue composition of 80% adipose and 20% glandular tissue, or even a 100% adipose tissue, would be recommended to avoid dose under-prescription.
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Affiliation(s)
- Paula Ibáñez
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.
| | - Amaia Villa-Abaunza
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain
| | - José Manuel Udías
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
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Richtsmeier D, Rodesch PA, Iniewski K, Bazalova-Carter M. Material decomposition with a prototype photon-counting detector CT system: expanding a stoichiometric dual-energy CT method via energy bin optimization and K-edge imaging. Phys Med Biol 2024; 69:055001. [PMID: 38306974 DOI: 10.1088/1361-6560/ad25c8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 02/01/2024] [Indexed: 02/04/2024]
Abstract
Objective.Computed tomography (CT) has advanced since its inception, with breakthroughs such as dual-energy CT (DECT), which extracts additional information by acquiring two sets of data at different energies. As high-flux photon-counting detectors (PCDs) become available, PCD-CT is also becoming a reality. PCD-CT can acquire multi-energy data sets in a single scan by spectrally binning the incident x-ray beam. With this, K-edge imaging becomes possible, allowing high atomic number (high-Z) contrast materials to be distinguished and quantified. In this study, we demonstrated that DECT methods can be converted to PCD-CT systems by extending the method of Bourqueet al(2014). We optimized the energy bins of the PCD for this purpose and expanded the capabilities by employing K-edge subtraction imaging to separate a high-atomic number contrast material.Approach.The method decomposes materials into their effective atomic number (Zeff) and electron density relative to water (ρe). The model was calibrated and evaluated using tissue-equivalent materials from the RMI Gammex electron density phantom with knownρevalues and elemental compositions. TheoreticalZeffvalues were found for the appropriate energy ranges using the elemental composition of the materials.Zeffvaried slightly with energy but was considered a systematic error. Anex vivobovine tissue sample was decomposed to evaluate the model further and was injected with gold chloride to demonstrate the separation of a K-edge contrast agent.Main results.The mean root mean squared percent errors on the extractedZeffandρefor PCD-CT were 0.76% and 0.72%, respectively and 1.77% and 1.98% for DECT. The tissue types in theex vivobovine tissue sample were also correctly identified after decomposition. Additionally, gold chloride was separated from theex vivotissue sample with K-edge imaging.Significance.PCD-CT offers the ability to employ DECT material decomposition methods, along with providing additional capabilities such as K-edge imaging.
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Affiliation(s)
- Devon Richtsmeier
- Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
| | - Pierre-Antoine Rodesch
- Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
| | - Kris Iniewski
- Redlen Techologies, 1763 Sean Heights, Saanichton, British Columbia V8M 1X6, Canada
| | - Magdalena Bazalova-Carter
- Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
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Nasir Z, Probst L, Schneider F, Clausen S, Bürgy D, Glatting G, Nwankwo O. Organ absorbed doses in the IORT treatment of breast cancer with the INTRABEAM device: a Monte-Carlo study. Biomed Phys Eng Express 2023; 9. [PMID: 36745910 DOI: 10.1088/2057-1976/acb941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/06/2023] [Indexed: 02/08/2023]
Abstract
Purpose: The current prescription and the assessment of the delivered absorbed dose in intraoperative radiation therapy (IORT) with the INTRABEAM system rely mainly on depth-dose measurements in water. The accuracy of this approach is limited because tissue heterogeneity is ignored. It is also difficult to accurately determine the dose delivered to the patient experimentally as the steep dose gradient is highly sensitive to geometric errors. Our goal is to determine the dose to the target volume and the organs at risk of a clinical breast cancer patient from treatment with the system.Methods: A homogeneous water-equivalent CT dataset was derived from the preoperative CT scan of a patient by setting all materials in the patient volume as water-equivalent. This homogeneous CT data represents the current assumption of a homogenous patient, while the original CT data is considered the ground truth. An in-house Monte Carlo algorithm was used to simulate the delivered dose in both setups for a prescribed treatment dose of 20 Gy to the surface of the 3.5 cm diameter spherical applicator.Results: The doses received by 2% (D2%) of the target volume for the homogeneous and heterogeneous geometries are 16.26 Gy and 9.33 Gy, respectively. The D2% for the heart are 0.035 Gy and 0.119 Gy for the homogeneous and heterogeneous geometries, respectively. This trend is also observed for the other organs at risk.Conclusions: The assumption of a homogeneous patient overestimates the dose to the target volume and underestimates the doses to the organs at risk.
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Affiliation(s)
- Zulfa Nasir
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University. Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.,Department of Physics, Faculty of Mathematics and Natural Sciences, Riau University, Bina Widya Campus, Pekanbaru, 28293, Riau, Indonesia
| | - Luis Probst
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University. Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Frank Schneider
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University. Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Sven Clausen
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University. Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Daniel Bürgy
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University. Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Gerhard Glatting
- Medical Radiation Physics, Department of Nuclear Medicine, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Obioma Nwankwo
- Strahlentherapie Rhein/Pfalz, Praxis für Strahlentherapie Neustadt, Stiftstraße 15, 67434 Neustadt, Germany
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Assam I, Vijande J, Ballester F, Pérez-Calatayud J, Poppe B, Siebert FA. Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for 125 I prostate implants. Med Phys 2022; 49:6195-6208. [PMID: 35925023 DOI: 10.1002/mp.15865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/24/2022] [Accepted: 06/25/2022] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Monte Carlo (MC) simulation studies, aimed at evaluating the magnitude of tissue heterogeneity in 125 I prostate permanent seed implant brachytherapy (BT), customarily use clinical post-implant CT images to generate a virtual representation of a realistic patient model (virtual patient model). Metallic artifact reduction (MAR) techniques and tissue assignment schemes (TAS) are implemented on the post-implant CT images to mollify metallic artifacts due to BT seeds and to assign tissue types to the voxels corresponding to the bright seed spots and streaking artifacts, respectively. The objective of this study is to assess the combined influence of MAR and TAS on MC absorbed dose calculations in post-implant CT-based phantoms. The virtual patient models used for 125 I prostate implant MC absorbed dose calculations in this study are derived from the CT images of an external radiotherapy prostate patient without BT seeds and prostatic calcifications, thus averting the need to implement MAR and TAS. METHODS The geometry of the IsoSeed I25.S17plus source is validated by comparing the MC calculated results of the TG-43 parameters for the line source approximation with the TG-43U1S2 consensus data. Four MC absorbed dose calculations are performed in two virtual patient models using the egs_brachy MC code: (1) TG-43-based Dw,w-TG 43 , (2) Dw,w-MBDC that accounts for interseed scattering and attenuation (ISA), (3) Dm,m that examines ISA and tissue heterogeneity by scoring absorbed dose in tissue, and (4) Dw,m that unlike Dm,m scores absorbed dose in water. The MC absorbed doses (1) and (2) are simulated in a TG-43 patient phantom derived by assigning the densities of every voxel to 1.00 g cm-3 (water), whereas MC absorbed doses (3) and (4) are scored in the TG-186 patient phantom generated by mapping the mass density of each voxel to tissue according to a CT calibration curve. The MC absorbed doses calculated in this study are compared with VariSeed v8.0 calculated absorbed doses. To evaluate the dosimetric effect of MAR and TAS, the MC absorbed doses of this work (independent of MAR and TAS) are compared to the MC absorbed doses of different 125 I source models from previous studies that were calculated with different MC codes using post-implant CT-based phantoms generated by implementing MAR and TAS on post-implant CT images. RESULTS The very good agreement of TG-43 parameters of this study and the published consensus data within 3% validates the geometry of the IsoSeed I25.S17plus source. For the clinical studies, the TG-43-based calculations show a D90 overestimation of more than 4% compared to the more realistic MC methods due to ISA and tissue composition. The results of this work generally show few discrepancies with the post-implant CT-based dosimetry studies with respect to the D90 absorbed dose metric parameter. These discrepancies are mainly Type B uncertainties due to the different 125 I source models and MC codes. CONCLUSIONS The implementation of MAR and TAS on post-implant CT images have no dosimetric effect on the 125 I prostate MC absorbed dose calculation in post-implant CT-based phantoms.
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Affiliation(s)
- Isong Assam
- UKSH, Campus Kiel, Clinic of Radiotherapy (Radiooncology), Kiel, Germany
| | - Javier Vijande
- Departamento de Física Atómica, Molecular y Nuclear, Universitat de Valencia (UV), Burjassot, Spain.,Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED), Instituto de Investigación Sanitaria La Fe (IIS-La Fe), Universitat de Valencia (UV), Valencia, Spain.,Instituto de Física Corpuscular, IFIC (UV-CSIC), Burjassot, Spain
| | - Facundo Ballester
- Departamento de Física Atómica, Molecular y Nuclear, Universitat de Valencia (UV), Burjassot, Spain.,Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED), Instituto de Investigación Sanitaria La Fe (IIS-La Fe), Universitat de Valencia (UV), Valencia, Spain
| | - José Pérez-Calatayud
- Radiotherapy Department, La Fe Hospital, Valencia, Spain.,Radiotherapy Department, Clinica Benidorm, Alicante, Spain
| | - Björn Poppe
- Center for Radiotherapy and Radiation Oncology - University Center for Medical Radiation Physics, Pius-Hospital, Medical Campus of Carl-von-Ossietzky University of Oldenburg, Oldenburg, Germany
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Chen L, Zhu GY, Jin ZC, Zhong BY, Wang Y, Lu J, Pan T, Teng GJ, Guo JH. Efficacy and Safety of Radioactive 125I Seed Implantation for Patients with Oligo-Recurrence Soft Tissue Sarcomas. Cardiovasc Intervent Radiol 2022; 45:808-813. [PMID: 35316381 DOI: 10.1007/s00270-022-03077-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 01/17/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the efficacy and safety of computed tomography-guided radioactive iodine-125 (125I) seed implantation for oligo-recurrence soft tissue sarcomas following surgical resection. MATERIALS AND METHODS Patients with oligo-recurrence soft tissue sarcomas after curative surgical resection between June 2013 and December 2020 were included. The primary outcome measure was objective response rate according to the Response Evaluation Criteria in Solid Tumors (RECIST 1.1). The secondary outcomes included progression-free survival, overall survival, and safety profiles. RESULTS Twenty-nine patients receiving computed tomography-guided 125I seed implantation were included in the study. The objective response rates at 2-, 6- and 12-month follow-up were 48.3%, 65.5% and 40.9%, respectively. The median progression-free survival was 11.3 months. The median overall survival was 25.1 months, with a 1- and 2-year overall survival rate of 81.5% and 50.0%, respectively. No severe treatment-related adverse effects occured. CONCLUSION 125I seed implantation has the potential to be an effective and safe treatment for oligo-recurrence soft tissue sarcomas after surgical resection.
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Affiliation(s)
- Li Chen
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Guang-Yu Zhu
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Zhi-Cheng Jin
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Bin-Yan Zhong
- Department of Interventional Radiology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Yong Wang
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Jian Lu
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Tao Pan
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Gao-Jun Teng
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China
| | - Jin-He Guo
- Department of Radiology, Center of Interventional Radiology and Vascular Surgery, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing, 210009, China.
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Kruis MF. Improving radiation physics, tumor visualisation, and treatment quantification in radiotherapy with spectral or dual-energy CT. J Appl Clin Med Phys 2021; 23:e13468. [PMID: 34743405 PMCID: PMC8803285 DOI: 10.1002/acm2.13468] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/13/2021] [Accepted: 10/19/2021] [Indexed: 12/11/2022] Open
Abstract
Over the past decade, spectral or dual‐energy CT has gained relevancy, especially in oncological radiology. Nonetheless, its use in the radiotherapy (RT) clinic remains limited. This review article aims to give an overview of the current state of spectral CT and to explore opportunities for applications in RT. In this article, three groups of benefits of spectral CT over conventional CT in RT are recognized. Firstly, spectral CT provides more information of physical properties of the body, which can improve dose calculation. Furthermore, it improves the visibility of tumors, for a wide variety of malignancies as well as organs‐at‐risk OARs, which could reduce treatment uncertainty. And finally, spectral CT provides quantitative physiological information, which can be used to personalize and quantify treatment.
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Akhavanallaf A, Mohammadi R, Shiri I, Salimi Y, Arabi H, Zaidi H. Personalized brachytherapy dose reconstruction using deep learning. Comput Biol Med 2021; 136:104755. [PMID: 34388458 DOI: 10.1016/j.compbiomed.2021.104755] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/05/2021] [Accepted: 08/05/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND PURPOSE Accurate calculation of the absorbed dose delivered to the tumor and normal tissues improves treatment gain factor, which is the major advantage of brachytherapy over external radiation therapy. To address the simplifications of TG-43 assumptions that ignore the dosimetric impact of medium heterogeneities, we proposed a deep learning (DL)-based approach, which improves the accuracy while requiring a reasonable computation time. MATERIALS AND METHODS We developed a Monte Carlo (MC)-based personalized brachytherapy dosimetry simulator (PBrDoseSim), deployed to generate patient-specific dose distributions. A deep neural network (DNN) was trained to predict personalized dose distributions derived from MC simulations, serving as ground truth. The paired channel input used for the training is composed of dose distribution kernel in water medium along with the full-volumetric density maps obtained from CT images reflecting medium heterogeneity. RESULTS The predicted single-dwell dose kernels were in good agreement with MC-based kernels serving as reference, achieving a mean relative absolute error (MRAE) and mean absolute error (MAE) of 1.16 ± 0.42% and 4.2 ± 2.7 × 10-4 (Gy.sec-1/voxel), respectively. The MRAE of the dose volume histograms (DVHs) between the DNN and MC calculations in the clinical target volume were 1.8 ± 0.86%, 0.56 ± 0.56%, and 1.48 ± 0.72% for D90, V150, and V100, respectively. For bladder, sigmoid, and rectum, the MRAE of D5cc between the DNN and MC calculations were 2.7 ± 1.7%, 1.9 ± 1.3%, and 2.1 ± 1.7%, respectively. CONCLUSION The proposed DNN-based personalized brachytherapy dosimetry approach exhibited comparable performance to the MC method while overcoming the computational burden of MC calculations and oversimplifications of TG-43.
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Affiliation(s)
- Azadeh Akhavanallaf
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva 4, Switzerland
| | - Reza Mohammadi
- Department of Medical Physics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Isaac Shiri
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva 4, Switzerland
| | - Yazdan Salimi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva 4, Switzerland
| | - Hossein Arabi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva 4, Switzerland
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211, Geneva 4, Switzerland; Geneva University Neurocenter, Geneva University, CH-1205, Geneva, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, 9700 RB, Groningen, Netherlands; Department of Nuclear Medicine, University of Southern Denmark, DK-500, Odense, Denmark.
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ARAS S. The Investigation of Tissue Composition Effects on Dose Distributions Using Monte Carlo Method in Permanent Prostate Brachytherapy. CLINICAL AND EXPERIMENTAL HEALTH SCIENCES 2021. [DOI: 10.33808/clinexphealthsci.884245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Zaichick V, Wynchank S. Reference man for radiological protection: 71 chemical elements' content of the prostate gland (normal and cancerous). RADIATION AND ENVIRONMENTAL BIOPHYSICS 2021; 60:165-178. [PMID: 33389150 DOI: 10.1007/s00411-020-00884-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Frequently knowledge of elemental content of human organs and tissues is required for a variety of applications. These can include brachytherapy and radiotherapy planning, radiation dosimetry and radiation protection. Revised reference values of chemical element mass fractions in normal and cancerous prostate tissues of the Reference (European Caucasian) Man are suggested as a result of this work. Autopsies of 37 apparently healthy males (mean age 55 ± 11 years, range 41-87 years) provided the prostatic tissues studied. The investigated individuals lived in a non-industrial, Central European region of Russia and had suffered sudden death. Also, tissues were studied from 62 subjects with prostate cancer (mean age 65 ± 10 years, range 40-79 years). Sixty-seven elemental mass fractions were determined in each of these 99 prostates. Analytical methods employed were inductively coupled plasma atomic emission spectrometry, neutron activation analysis with high-resolution spectrometry of short-lived and long-lived radionuclides, energy dispersive X-ray fluorescence analysis, and inductively coupled plasma mass spectrometry. Whichever method was employed, the necessary quality control measures were utilized. Results presented here include a systematic analysis of both the prostatic data presented here for 67 elements and also others' published findings, to make a total of 71 elemental mass fraction values.
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Affiliation(s)
- Vladimir Zaichick
- Department of Radionuclide Diagnostics, Medical Radiological Research Centre, Korolyev St. 4, Obninsk, 249036, Kaluga Region, Russia.
| | - Sinclair Wynchank
- Strategic Health Innovation Partnerships, Medical Research Council, Tygerberg, 7505, Western Cape, South Africa
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Deering SG, Hilts M, Batchelar D, Crook J, Thomson RM. Dosimetric investigation of 103Pd permanent breast seed implant brachytherapy based on Monte Carlo calculations. Brachytherapy 2021; 20:686-694. [PMID: 33551273 DOI: 10.1016/j.brachy.2020.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 12/03/2020] [Accepted: 12/19/2020] [Indexed: 10/22/2022]
Abstract
PURPOSE Permanent breast seed implant using 103Pd is emerging as an effective adjuvant radiation technique for early stage breast cancer. However, clinical dose evaluations follow the water-based TG-43 approach with its considerable approximations. Toward clinical adoption of advanced TG-186 model-based dose evaluations, this study presents a comprehensive investigation for permanent breast seed implant considering both target and normal tissue doses. METHODS AND MATERIALS Dose calculations are performed with the free open-source Monte Carlo (MC) code, egs_brachy, using two types of virtual patient models: TG43sim (simulated TG-43 conditions) and MCref (heterogeneous tissue modeling from patient CT, seeds at implant angle) for 35 patients. The sensitivity of dose metrics to seed orientation and tissue segmentation are assessed. RESULTS In the target volume, D90 is 14.1 ± 5.8% lower with MCref than with TG43sim, on average. Conversely, normal tissue doses are generally higher with MCref than with TG43sim, for example, by 22 ± 13% for skin D1cm2, 82 ± 7% for ribs Dmax, and 71 ± 23% for heart D1cm3. Discrepancies between MCref and TG43sim doses vary over the patient cohort, as well as with the tissue and metric considered. Skin doses are particularly sensitive to seed orientation, with average difference of 4% (maximum 28%) in D1cm2 for seeds modeled vertically (egs_brachy default) compared with those aligned with implant angle. CONCLUSIONS TG-43 dose evaluations generally underestimate doses to critical normal organs/tissues while overestimating target doses. There is considerable variation in MCref and TG43sim on a patient-by-patient basis, motivating clinical adoption of patient-specific MC dose calculations. The MCref framework presented herein provides a consistent modeling approach for clinical implementation of advanced TG-186 dose calculations.
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Affiliation(s)
- Stephen G Deering
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Canada
| | - Michelle Hilts
- Department of Medical Physics, BC Cancer-Kelowna, Kelowna, British Columbia, Canada; Department of Physics, IK Barber School of Arts and Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Deidre Batchelar
- Department of Medical Physics, BC Cancer-Kelowna, Kelowna, British Columbia, Canada; Department of Physics, IK Barber School of Arts and Sciences, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - Juanita Crook
- Department of Radiation Oncology, BC Cancer-Kelowna, Kelowna, British Columbia, Canada
| | - Rowan M Thomson
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Canada.
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Srinivasan K, Samuel EJJ. Target biological tissue and energy influence on dose enhancement factor produced by gold nanoparticles and its relevant radiological properties. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.108912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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12
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Watson PGF, Popovic M, Liang L, Tomic N, Devic S, Seuntjens J. Clinical Implication of Dosimetry Formalisms for Electronic Low-Energy Photon Intraoperative Radiation Therapy. Pract Radiat Oncol 2020; 11:e114-e121. [PMID: 32795615 DOI: 10.1016/j.prro.2020.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 05/27/2020] [Accepted: 07/27/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE Intraoperative radiation therapy (IORT) using the INTRABEAM, a miniature x-ray source, has shown to be effective in treating breast cancer. However, recent investigations have suggested a significant deviation between the reported and delivered doses. In this work, the dose delivered by INTRABEAM in the TARGIT breast protocol was investigated, along with the dose from the Xoft Axxent, another source used in breast IORT. METHODS AND MATERIALS The absorbed dose from the INTRABEAM was determined from ionization chamber measurements using: (a) the manufacturer-recommended formula (Zeiss V4.0 method), (b) a Monte Carlo calculated chamber conversion factor (CQ method), and (c) the formula consistent with the TARGIT breast protocol (TARGIT method). The dose from the Xoft Axxent was determined from ionization chamber measurements using the Zeiss V4.0 method and calculated using the American Association of Physicists in Medicine TG-43 formalism. RESULTS For a nominal TARGIT prescription of 20 Gy, the dose at the INTRABEAM applicator surface ranged from 25.2 to 31.7 Gy according to the CQ method for the largest (5 cm) and smallest (1.5 cm) diameter applicator, respectively. The Zeiss V4.0 method results were 7% to 10% lower (23.2 to 28.6 Gy). At 1 cm depth, the CQ and Zeiss V4.0 absorbed doses were also larger than those predicted by the TARGIT method. The dose at 1 cm depth from the Xoft Axxent for a surface dose of 20 Gy was slightly less than INTRABEAM (3%-7% compared with CQ method). An exception was for the 3 cm applicator, where the Xoft dose was appreciably lower (31%). CONCLUSIONS The doses delivered in the TARGIT breast protocol with INTRABEAM were significantly greater than the prescribed 20 Gy and depended on the size of spherical applicator used. Breast IORT treatments with the Xoft Axxent received less dose compared with TARGIT INTRABEAM, which could have implications for studies comparing clinical outcomes between the 2 devices.
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Affiliation(s)
| | - Marija Popovic
- Medical Physics Unit, McGill University, Montreal, QC, Canada
| | - Liheng Liang
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Nada Tomic
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Slobodan Devic
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, QC, Canada
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Jacobsen MC, Thrower SL. Multi-energy computed tomography and material quantification: Current barriers and opportunities for advancement. Med Phys 2020; 47:3752-3771. [PMID: 32453879 PMCID: PMC8495770 DOI: 10.1002/mp.14241] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 04/20/2020] [Accepted: 05/07/2020] [Indexed: 12/21/2022] Open
Abstract
Computed tomography (CT) technology has rapidly evolved since its introduction in the 1970s. It is a highly important diagnostic tool for clinicians as demonstrated by the significant increase in utilization over several decades. However, much of the effort to develop and advance CT applications has been focused on improving visual sensitivity and reducing radiation dose. In comparison to these areas, improvements in quantitative CT have lagged behind. While this could be a consequence of the technological limitations of conventional CT, advanced dual-energy CT (DECT) and photon-counting detector CT (PCD-CT) offer new opportunities for quantitation. Routine use of DECT is becoming more widely available and PCD-CT is rapidly developing. This review covers efforts to address an unmet need for improved quantitative imaging to better characterize disease, identify biomarkers, and evaluate therapeutic response, with an emphasis on multi-energy CT applications. The review will primarily discuss applications that have utilized quantitative metrics using both conventional and DECT, such as bone mineral density measurement, evaluation of renal lesions, and diagnosis of fatty liver disease. Other topics that will be discussed include efforts to improve quantitative CT volumetry and radiomics. Finally, we will address the use of quantitative CT to enhance image-guided techniques for surgery, radiotherapy and interventions and provide unique opportunities for development of new contrast agents.
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Affiliation(s)
- Megan C. Jacobsen
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sara L. Thrower
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Abstract
The purpose of this study was to review the limitations of dose calculation formalisms for photon-emitting brachytherapy sources based on the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) report and to provide recommendations to transition to model-based dose calculation algorithms. Additionally, an overview of these algorithms and approaches is presented. The influence of tissue and seed/applicator heterogeneities on brachytherapy dose distributions for breast, gynecologic, head and neck, rectum, and prostate cancers as well as eye plaques and electronic brachytherapy treatments were investigated by comparing dose calculations based on the TG-43 formalism and model-based dose calculation algorithms.
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Tom MC, Joshi N, Vicini F, Chang AJ, Hong TS, Showalter TN, Chao ST, Wolden S, Wu AJ, Martin D, Husain Z, Badiyan SN, Kolar M, Sherertz T, Mourtada F, Cohen GN, Shah C. The American Brachytherapy Society consensus statement on intraoperative radiation therapy. Brachytherapy 2019; 18:242-257. [PMID: 31084904 DOI: 10.1016/j.brachy.2019.01.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 01/30/2019] [Indexed: 12/12/2022]
Abstract
PURPOSE Although radiation therapy has traditionally been delivered with external beam or brachytherapy, intraoperative radiation therapy (IORT) represents an alternative that may shorten the course of therapy, reduce toxicities, and improve patient satisfaction while potentially lowering the cost of care. At this time, there are limited evidence-based guidelines to assist clinicians with patient selection for IORT. As such, the American Brachytherapy Society presents a consensus statement on the use of IORT. METHODS Physicians and physicists with expertise in intraoperative radiation created a site-directed guideline for appropriate patient selection and utilization of IORT. RESULTS Several IORT techniques exist including radionuclide-based high-dose-rate, low-dose-rate, electron, and low-energy electronic. In breast cancer, IORT as monotherapy should only be used on prospective studies. IORT can be considered in the treatment of sarcomas with close/positive margins or recurrent sarcomas. IORT can be considered in conjunction with external beam radiotherapy for retroperitoneal sarcomas. IORT can be considered for colorectal malignancies with concern for positive margins and in the setting of recurrent gynecologic cancers. For thoracic, head and neck, and central nervous system malignancies, utilization of IORT should be evaluated on a case-by-case basis. CONCLUSIONS The present guidelines provide clinicians with a summary of current data regarding IORT by treatment site and guidelines for the appropriate patient selection and safe utilization of the technique. High-dose-rate, low-dose-rate brachytherapy methods are appropriate when IORT is to be delivered as are electron and low-energy based on the clinical scenario.
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Affiliation(s)
- Martin C Tom
- Department of Radiation Oncology, Taussig Cancer Institute, Cleveland, OH
| | - Nikhil Joshi
- Department of Radiation Oncology, Taussig Cancer Institute, Cleveland, OH
| | - Frank Vicini
- 21st Century Oncology, Michigan Healthcare Professionals, Farmington Hills, MI
| | | | - Theodore S Hong
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA
| | - Timothy N Showalter
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA
| | - Samuel T Chao
- Department of Radiation Oncology, Taussig Cancer Institute, Cleveland, OH
| | - Suzanne Wolden
- Departments of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Abraham J Wu
- Departments of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Douglas Martin
- Department of Radiation Oncology, Ohio State University, Columbus, OH
| | - Zain Husain
- Department of Therapeutic Radiology, Yale University, New Haven, CT
| | - Shahed N Badiyan
- Department of Radiation Oncology, Washington University, St. Louis, MO
| | - Matthew Kolar
- Department of Radiation Oncology, Taussig Cancer Institute, Cleveland, OH
| | - Tracy Sherertz
- Department of Radiation Oncology, Kaiser Capitol Hill, Seattle, WA
| | - Firas Mourtada
- Helen F. Graham Cancer Center & Research Institute, Christiana Care Health System, Newark, DE
| | - Gilad N Cohen
- Department Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Chirag Shah
- Department of Radiation Oncology, Taussig Cancer Institute, Cleveland, OH.
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Evaluation of BrachyDose Monte Carlo code for HDR brachytherapy: dose comparison against Acuros®BV and TG-43 algorithms. JOURNAL OF RADIOTHERAPY IN PRACTICE 2019. [DOI: 10.1017/s1460396919000220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractAim:The aim of this study is to investigate the accuracy of dose distributions calculated by the BrachyDose Monte Carlo (MC) code in heterogeneous media for high-dose-rate (HDR) brachytherapy and to evaluate its usability in the clinical brachytherapy treatment planning systems.Materials and methods:For dose comparisons, three different dose calculation algorithms were used in this study. Namely, BrachyDose MC code, Eclipse TG-43 dose calculation tool and Acuros®BV model-based dose calculation algorithm (MBDCA). Dose distributions were obtained using any of the above codes in various scenarios including ‘homogenous water medium scenario’, an ‘extreme case heterogeneous media scenario’ and clinically important ‘a patient with a cervical cancer scenario’. In the ‘extreme case, heterogeneous media scenario’, geometry is a rare combination of unusual high-density and low-density materials and it is chosen to provide a test environment for the propagation of photons in the interface of two materials with different absorption and scattering properties. GammaMed 192Ir Model 12i Source is used as the HDR brachytherapy source in this study. Dose calculations were performed for the cases where there is either a single source or five sources planted into the phantom geometry in all homogenous water phantom and extreme case heterogeneous media scenarios. For the scenario a patient with a cervical cancer, dose calculations were performed in a voxelized rectilinear phantom, which is constructed from a series of computed tomography (CT) slices of a patient, which are obtained from a CT device.Results:In homogeneous water phantom scenario, we observed no statistically significant dose differences among the dose distributions calculated by any of the three algorithms at almost every point in the geometry. In the extreme case heterogeneous media scenario, the dose calculation engines Acuros®BV and BrachyDose are agreed well within statistics in every region of the geometry and even in the points close to the interfaces of low-density and high-density materials. On the other hand, the dose values calculated by these two codes are significantly different from those calculated by the TG-43 algorithm. In the ‘a patient with a cervical cancer scenario’, the calculated D2cc dose difference between Acuros®BV and BrachyDose codes is within 2% in the rectum and 11% for the bladder and sigmoid. There was no meaningful difference in the mean dose values between MBDCAs in the bone structures.Conclusions:In this study, the accurate dose calculation capabilities of the BrachyDose program in HDR brachytherapy were investigated on various scenarios and, as a MC dose calculation tool, its effectiveness in HDR brachytherapy was demonstrated by comparative dose analysis.
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Famulari G, Renaud MA, Poole CM, Evans MDC, Seuntjens J, Enger SA. RapidBrachyMCTPS: a Monte Carlo-based treatment planning system for brachytherapy applications. ACTA ACUST UNITED AC 2018; 63:175007. [DOI: 10.1088/1361-6560/aad97a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Lalonde A, Remy C, Simard M, Bouchard H. Unsupervised classification of tissues composition for Monte Carlo dose calculation. Phys Med Biol 2018; 63:15NT01. [PMID: 29962371 DOI: 10.1088/1361-6560/aad05f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purpose of this study is to investigate the potential of k-means clustering to efficiently reduce the variety of materials needed in Monte Carlo (MC) dose calculation. A numerical phantom with 31 human tissues surrounded by water is created. K-means clustering is used to group the tissues in clusters of constant elemental composition. Four different distance measures are used to perform the clustering technique: Euclidean, Standardized Euclidean, Chi-Squared and Cityblock. Dose distributions are calculated with MC simulations for both low-kV photons and MeV protons using the clustered and reference elemental composition. Comparison between the dose distributions in the clustered and non-clustered phantom are made to assess the impact of clustering with each distance measure. The statistical significance of the differences observed between the four different metrics is determined by comparing the accuracy of energy absorption coefficients (EAC) of low-kV photons and proton stopping powers relative to water (SPR) for repeated clustering procedures. The performance of the proposed approach for a larger number of original materials is evaluated similarly by using a population of 62 000 statistically generated materials grouped into classes defined with supervised and unsupervised classification. In the phantom geometry, the Chi-Squared distance is the one introducing the smallest error on dose distribution and significant differences are observed between the EAC and SPR values predicted by each distance metric. The proposed approach is also shown to be equivalent to a state-of-the-art supervised classification method for proton therapy, but beneficial for low-kV photons applications. In conclusion, k-means clustering successfully reduces the variety of materials needed for accurate MC dose calculation. Based on the performance of four distance measures, we conclude that k-means clustering using the Chi-Squared distance introduces the smallest errors on dose distribution. The method is shown to yield similar or improved accuracy on key physical parameters compared to supervised classification.
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Affiliation(s)
- Arthur Lalonde
- Département de Physique, Université de Montréal, Pavillon Roger-Gaudry, 2900 Boulevard Édouard-Montpetit, Montréal, Québec H3T 1J4, Canada
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Watson PGF, Bekerat H, Papaconstadopoulos P, Davis S, Seuntjens J. An investigation into the INTRABEAM miniature x-ray source dosimetry using ionization chamber and radiochromic film measurements. Med Phys 2018; 45:4274-4286. [PMID: 29935088 DOI: 10.1002/mp.13059] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/22/2018] [Accepted: 06/15/2018] [Indexed: 02/28/2024] Open
Abstract
PURPOSE Intraoperative radiotherapy using The INTRABEAM System (Carl Zeiss Meditec AG, Jena, Germany), a miniature low-energy x-ray source, has proven to be an effective modality in the treatment of breast cancer. However, some uncertainties remain in its dosimetry. In this work, we investigated the INTRABEAM system dosimetry by performing ionization chamber and radiochromic film measurements of absorbed dose in a water phantom. METHODS Ionization chamber measurements were performed with a PTW 34013 parallel-plate soft x-ray chamber at source to detector distances of 5 to 30 mm calculated using (a) the dose formula consistent with the TARGIT breast protocol (TARGIT), (b) the formula recommended by the manufacturer (Zeiss), and (c) the recently proposed CQ formalism of Watson et al. (Physics in Medicine & Biology, 2018;63:015016) EBT3 Gafchromic film measurements were made at the same depths in water. To account for the energy dependence of EBT3 film, multiple dose response calibration curves were employed across a range of photon beam qualities relevant to the INTRABEAM spectrum in water. RESULTS At all depths investigated, the TARGIT dose was significantly lower than that measured by the Zeiss and CQ methods, as well as film. These dose differences ranged from 14% to as large as 80%. In general, the doses measured by film, and the Zeiss and CQ methods were in good agreement to within measurement uncertainties (5-6%). CONCLUSIONS These results suggest that the TARGIT dose underestimates the physical dose to water from the INTRABEAM source. Understanding the correlation between the TARGIT and physical dose is important for any studies wishing to make dosimetric comparisons between the INTRABEAM and other radiation emitting devices.
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Affiliation(s)
| | - Hamed Bekerat
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Pavlos Papaconstadopoulos
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Stephen Davis
- Medical Physics Unit, McGill University, Montreal, QC, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, QC, Canada
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van der Heyden B, Schyns LEJR, Podesta M, Vaniqui A, Almeida IP, Landry G, Verhaegen F. VOXSI: A voxelized single- and dual-energy CT scenario generator for quantitative imaging. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2018; 6:47-52. [PMID: 33458388 PMCID: PMC7807865 DOI: 10.1016/j.phro.2018.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 11/23/2022]
Abstract
Background and purpose Dedicated CT simulation models have the potential to investigate several acquisition, reconstruction, or post-processing parameters without giving any radiation dose to patients. A software program was developed for the simulation and the analysis of single-energy and dual-energy CT images. Simulation and analysis functionalities of the software are described. Materials and methods In the software, named VOXSI (VOXelized CT SImulator), the X-ray source, user specified simulation geometry, CT setup and the detector energy response can be varied. CT image reconstructions can be performed with an implementation of the ASTRA toolbox. In the DECT post processing toolkit, GUI tools are provided to calculate effective atomic number, relative electron density, pseudo-monoenergetic images, and material map images. Quantitative CT number validation, based on a RMI 467 tissue characterization phantom model, was performed between experimental and simulated CT scans at three different X-ray tube potentials (80, 120, and 140 kVp) with a third generation CT scanner. Results Overall, a good agreement was found for the mean CT numbers of the RMI 467 inserts. For all energies, the maximum difference in CT numbers between experimental and simulated data was below 17 HU for the soft tissues and below 48 HU for the osseous tissues. Conclusion The software’s simulation algorithm showed a good agreement between the CT measurements and CT simulations of the RMI 467 phantom at different energies. The capabilities of the software are demonstrated by an elaborated dual-energy CT research example.
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Affiliation(s)
- Brent van der Heyden
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Lotte E J R Schyns
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Mark Podesta
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Ana Vaniqui
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Isabel P Almeida
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Guillaume Landry
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität, München, Am Coulombwall 1, 85748 Garching b. München, Germany
| | - Frank Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
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Mann-Krzisnik D, Verhaegen F, Enger SA. The influence of tissue composition uncertainty on dose distributions in brachytherapy. Radiother Oncol 2018; 126:394-410. [PMID: 29428259 DOI: 10.1016/j.radonc.2018.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/31/2017] [Accepted: 01/05/2018] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE Model-based dose calculation algorithms (MBDCAs) have evolved from serving as a research tool into clinical practice in brachytherapy. This study investigates primary sources of tissue elemental compositions used as input to MBDCAs and the impact of their variability on MBDCA-based dosimetry. MATERIALS AND METHODS Relevant studies were retrieved through PubMed. Minimum dose delivered to 90% of the target (D90), minimum dose delivered to the hottest specified volume for organs at risk (OAR) and mass energy-absorption coefficients (μen/ρ) generated by using EGSnrc "g" user-code were compared to assess the impact of compositional variability. RESULTS Elemental composition for hydrogen, carbon, oxygen and nitrogen are derived from the gross contents of fats, proteins and carbohydrates for any given tissue, the compositions of which are taken from literature dating back to 1940-1950. Heavier elements are derived from studies performed in the 1950-1960. Variability in elemental composition impacts greatly D90 for target tissues and doses to OAR for brachytherapy with low energy sources and less for 192Ir-based brachytherapy. Discrepancies in μen/ρ are also indicative of dose differences. CONCLUSIONS Updated elemental compositions are needed to optimize MBDCA-based dosimetry. Until then, tissue compositions based on gross simplifications in early studies will dominate the uncertainties in tissue heterogeneity.
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Affiliation(s)
| | - Frank Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, The Netherlands
| | - Shirin A Enger
- Medical Physics Unit, McGill University, Montreal, Canada; Department of Oncology, McGill University, Montreal, Canada; Research Institute of the McGill University Health Centre, Montreal, Canada
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Zwierzchowski G, Bieleda G, Skowronek J. Quality Assurance Procedures based on Dosimetric, Gamma Analysis as a Fast Reliable Tool for Commissioning Brachytherapy Treatment Planning Systems. Radiol Oncol 2018; 51:469-474. [PMID: 29333127 PMCID: PMC5765325 DOI: 10.1515/raon-2017-0050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 10/10/2017] [Indexed: 11/15/2022] Open
Abstract
Background Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT) treatment planning systems (TPS) are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA) procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms. The aim of this study was dosimetric verification of the calculation algorithm used in TPS when the CT/MRI ring applicator is used. Materials and methods Ring applicators with 26 and 30 mm diameters and a 60 mm intra-uterine tube with 60° angle were used for verification. Gafchromic® EBT films were used as dosimetric media. Dose grids, corresponding to each plane (dosimetric film location), were exported from the TPS as a raw data. Gafchromic® films were digitized after irradiation. gamma analysis of the data were performed using the OMNI Pro I’mRT® system, as recommended by the AAPM TG-119 rapport criterion for gamma analysis of 3%, 3 mm and a level of 95%. Results For the 26 mm and 30 mm rings, the average gamma ranged, respectively, from 0.1 to 0.44 and from 0.1 to 0.27. In both cases, 99% of the measured points corresponded with the calculated data. Conclusions This analysis showed excellent agreement between the dose distribution calculated with the TPS and the doses measured by Gafchromic films. This finding confirms the viability of using film dosimetry in BT.
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Affiliation(s)
- Grzegorz Zwierzchowski
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Medical Physics Department, Poznan, Poland
| | - Grzegorz Bieleda
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Medical Physics Department, Poznan, Poland
| | - Janusz Skowronek
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Brachytherapy Department, Poznan, Poland
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Abstract ID: 113 Accurate extraction of tissues parameters for Monte Carlo simulations using multi-energy CT. Phys Med 2017. [DOI: 10.1016/j.ejmp.2017.09.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Feasibility and clinical value of CT-guided 125I brachytherapy for metastatic soft tissue sarcoma after first-line chemotherapy failure. Eur Radiol 2017; 28:1194-1203. [PMID: 28956119 DOI: 10.1007/s00330-017-5036-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 08/01/2017] [Accepted: 08/14/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To evaluate the feasibility and usefulness of computed tomography (CT)-guided iodine125 (125I) brachytherapy for patients with metastatic soft tissue sarcoma (STS) after first-line chemotherapy failure. METHODS We recruited 93 patients with metastatic STS who had received first-line chemotherapy 4-6 times but developed progressive disease, from January 2010 to July 2015; 45 patients who had combined 125I brachytherapy and second-line chemotherapy (Group A), and 48 patients who received second-line CT only (Group B). RESULT In Group A, 49 125I seed implantation procedures were performed in 45 patients with 116 metastatic lesions; the primary success rate was 91.1% (41/45), without life-threatening complications. Local control rates at 3, 6, 12, 24 and 36 months were 71.1%, 62.2%, 46.7%, 28.9% and 11.1% for Group A, and 72.9%, 54.2%, 18.8%, 6.3% and 0% for Group B. Mean progression-free survival differed significantly (Group A: 7.1±1.3 months; Group B: 3.6 ±1.1 months; P<0.001; Cox proportional hazards regression analysis), but overall survival did not significantly differ (Group A: 16.9 ±5.1 months; Group B: 12.1 ± 4.8 months). Group A showed better symptom relief and quality of life than Group B. CONCLUSION CT-guided 125I brachytherapy is a feasible and valuable treatment for patients with metastatic STS. KEY POINTS • 125 I brachytherapy is feasible and valuable for treating metastatic soft tissue sarcoma. • 125 I brachytherapy represents a prominent activity in disease control. • 125 I brachytherapy can achieve better symptom relief and quality of life.
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Shimomura K, Araki F, Kono Y, Asai Y, Murakami T, Hyodo T, Okumura M, Matsumoto K, Monzen H, Nishimura Y. Identification of elemental weight fraction and mass density of humanoid tissue-equivalent materials using dual energy computed tomography. Phys Med 2017. [DOI: 10.1016/j.ejmp.2017.05.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Malusek A, Magnusson M, Sandborg M, Alm Carlsson G. A model-based iterative reconstruction algorithm DIRA using patient-specific tissue classification via DECT for improved quantitative CT in dose planning. Med Phys 2017; 44:2345-2357. [DOI: 10.1002/mp.12238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/16/2017] [Accepted: 03/10/2017] [Indexed: 11/10/2022] Open
Affiliation(s)
- Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Linköping Sweden
| | - Maria Magnusson
- Radiation Physics, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Linköping Sweden
- Computer Vision Laboratory, Department of Electrical Engineering; Linköping University; Linköping Sweden
| | - Michael Sandborg
- Radiation Physics, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Linköping Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences; Linköping University; Linköping Sweden
- Center for Medical Image Science and Visualization (CMIV); Linköping University; Linköping Sweden
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Wang J, Tanderup K, Cunha A, Damato AL, Cohen GN, Kudchadker RJ, Mourtada F. Magnetic resonance imaging basics for the prostate brachytherapist. Brachytherapy 2017; 16:715-727. [PMID: 28396178 DOI: 10.1016/j.brachy.2017.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 02/23/2017] [Accepted: 03/04/2017] [Indexed: 11/27/2022]
Abstract
Magnetic resonance imaging (MRI) is increasingly being used in radiation therapy, and integration of MRI into brachytherapy in particular is becoming more common. We present here a systematic review of the basic physics and technical aspects of incorporating MRI into prostate brachytherapy. Terminology and MRI system components are reviewed along with typical work flows in prostate high-dose-rate and low-dose-rate brachytherapy. In general, the brachytherapy workflow consists of five key components: diagnosis, implantation, treatment planning (scan + plan), implant verification, and delivery. MRI integration is discussed for diagnosis; treatment planning; and MRI-guided brachytherapy implants, in which MRI is used to guide the physical insertion of the brachytherapy applicator or needles. Considerations and challenges for establishing an MRI brachytherapy program are also discussed.
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Affiliation(s)
- Jihong Wang
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX.
| | - Kari Tanderup
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Adam Cunha
- Department of Radiation Oncology, University of California-San Francisco, CA
| | - Antonio L Damato
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Gil'ad N Cohen
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Rajat J Kudchadker
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX
| | - Firas Mourtada
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX; Department of Radiation Oncology, Helen F. Graham Cancer Center, Newark, DE; Department of Radiation Oncology, Bodine Cancer Center, Thomas Jefferson University, Philadelphia, PA.
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Nath R, Rivard MJ, DeWerd LA, Dezarn WA, Thompson Heaton H, Ibbott GS, Meigooni AS, Ouhib Z, Rusch TW, Siebert FA, Venselaar JLM. Guidelines by the AAPM and GEC-ESTRO on the use of innovative brachytherapy devices and applications: Report of Task Group 167. Med Phys 2017; 43:3178-3205. [PMID: 27277063 DOI: 10.1118/1.4951734] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used in the evaluation of innovative devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining the equivalence of the innovative treatment modality to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of innovative radiotherapy devices or applications is a critical part in which physicists should be actively involved. The physicist's role, along with physician colleagues, in this process is highlighted for innovative brachytherapy devices and applications and includes evaluation of (1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, (2) risks and benefits from a regulatory and safety perspective, and (3) resource assessment and preparedness. Further, it is suggested that any developed calibration methods be traceable to a primary standards dosimetry laboratory (PSDL) such as the National Institute of Standards and Technology in the U.S. or to other PSDLs located elsewhere such as in Europe. Clinical users should follow standards as approved by their country's regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the Accredited Dosimetry Calibration Laboratories in the U.S. is encouraged before a source is introduced into widespread routine clinical use. The American Association of Physicists in Medicine and the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) have developed guidelines for the safe and consistent application of brachytherapy using innovative devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of requirements of the U.S. Nuclear Regulatory Commission, U.S. Department of Transportation, International Electrotechnical Commission Medical Electrical Equipment Standard 60601, U.S. Food and Drug Administration, European Commission for CE Marking (Conformité Européenne), and institutional review boards and radiation safety committees.
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Affiliation(s)
- Ravinder Nath
- Department of Therapeutic Radiology, School of Medicine, Yale University, New Haven, Connecticut 06510
| | - Mark J Rivard
- Department of Radiation Oncology, School of Medicine, Tufts University, Boston, Massachusetts 02111
| | - Larry A DeWerd
- Accredited Dosimetry and Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706
| | - William A Dezarn
- Department of Radiation Oncology, School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157
| | | | - Geoffrey S Ibbott
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Ali S Meigooni
- Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada 89169
| | - Zoubir Ouhib
- Radiation Oncology, Lynn Regional Cancer Center, Delray Beach, Florida 33484
| | - Thomas W Rusch
- Xoft, Inc., A Subsidiary of iCAD, Inc., San Jose, California 95134
| | - Frank-André Siebert
- Clinic of Radiotherapy, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel 24105, Germany
| | - Jack L M Venselaar
- Department of Medical Physics and Engineering, Instituut Verbeeten, Tilburg LA 5000, The Netherlands
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Large-scale Retrospective Monte Carlo Dosimetric Study for Permanent Implant Prostate Brachytherapy. Int J Radiat Oncol Biol Phys 2017; 97:606-615. [DOI: 10.1016/j.ijrobp.2016.11.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/22/2016] [Accepted: 11/16/2016] [Indexed: 01/24/2023]
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Schyns LEJR, Almeida IP, van Hoof SJ, Descamps B, Vanhove C, Landry G, Granton PV, Verhaegen F. Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research. Br J Radiol 2016; 90:20160480. [PMID: 27683003 DOI: 10.1259/bjr.20160480] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system. METHODS The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Zeff) and relative electron densities (ρe) for phantom inserts with known elemental compositions and relative electron densities. RESULTS The optimal energy combination was determined to be 50 and 90 kVp. For this combination, Zeff and ρe can be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60 cGy. CONCLUSION Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Zeff and ρe. When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Zeff and ρe errors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system.
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Affiliation(s)
- Lotte E J R Schyns
- 1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Isabel P Almeida
- 1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Stefan J van Hoof
- 1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Benedicte Descamps
- 2 iMinds Medical IT-IBiTech-MEDISIP-INFINITY, De Pintelaan 185, Ghent, Belgium
| | - Christian Vanhove
- 2 iMinds Medical IT-IBiTech-MEDISIP-INFINITY, De Pintelaan 185, Ghent, Belgium
| | - Guillaume Landry
- 3 Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Patrick V Granton
- 1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Frank Verhaegen
- 1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.,4 Medical Physics Unit, Department of Oncology, McGill University, Montréal, QC, Canada
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Quast U, Kaulich TW, Álvarez-Romero JT, Carlsson Tedgren S, Enger SA, Medich DC, Mourtada F, Perez-Calatayud J, Rivard MJ, Zakaria GA. A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry. Phys Med 2016; 32:741-8. [PMID: 27237583 DOI: 10.1016/j.ejmp.2016.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 02/15/2016] [Accepted: 03/16/2016] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector's response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E¯(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality indexQ(BT)(E¯), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, Dw, around BT sources. MATERIALS AND METHODS While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT)(E¯)=TPR10(20)(E¯) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT)(E¯)=Dprim(r=2cm,θ0=90°)/Dprim(r0=1cm,θ0=90°), utilizing precise primary absorbed dose data, Dprim, from source reference databases, without additional MC-calculations. RESULTS AND DISCUSSION For BT photon sources used clinically, Q(BT)(E¯) enables to determine the effective mean linear attenuation coefficient μ¯(E) and thus the effective energy of the primary photons Eprim(eff)(r0,θ0) at the TG-43 reference position Pref(r0=1cm,θ0=90°), being close to the mean total photon energy E¯tot(r0,θ0). If one has calibrated detectors, published E¯tot(r) and the BT radiation quality correction factor [Formula: see text] for different BT radiation qualities Q and Q0, the detector's response can be determined and Dw(r,θ) measured in the vicinity of BT photon sources. CONCLUSIONS This novel brachytherapy photon radiation quality indexQ(BT) characterizes sufficiently accurate and precise the primary photon's penetration probability and scattering potential.
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Affiliation(s)
- Ulrich Quast
- Ex-University Hospital, Radiation Oncology Dept., Clinical Radiation Physics, D 45127 Essen, Germany.
| | - Theodor W Kaulich
- University-Hospital, Dept. of Radiation Oncology, Medical Physics, D 72076 Tübingen, Germany
| | | | - Sa Carlsson Tedgren
- Radiation Physics, IMH, Linköping University, SE 58185 Linköping, Sweden; Radiotherapy Physics and Engineering, Dept. of Medical Physics, Karolinska University Hospital, Stockholm, Sweden
| | - Shirin A Enger
- Medical Physics Unit, Dept. of Oncology, McGill University, CA H3AO64, Montréal, Québec, Canada
| | - David C Medich
- Dept. of Physics, Worcester Polytechnic Institute, Worcester, MA 01609, USA
| | - Firas Mourtada
- Radiation Oncology Dept., Helen F. Graham Cancer Center & Research Institute, Newark, DE 19713, USA
| | - Jose Perez-Calatayud
- Radiotherapy Dept., University Hospital La Fe, 46026 Valencia, Spain and Clinica Benidorm, Alicante, Spain
| | - Mark J Rivard
- Dept. of Radiation Oncology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - G Abu Zakaria
- Gummersbach Hospital, University of Cologne, Med. Rad. Physics, D 51643 Gummersbach, Germany; Dept. of Medical Physics and Biomedical Engineering, Gono University, Dhaka 1344, Bangladesh
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van Elmpt W, Landry G, Das M, Verhaegen F. Dual energy CT in radiotherapy: Current applications and future outlook. Radiother Oncol 2016; 119:137-44. [DOI: 10.1016/j.radonc.2016.02.026] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/13/2016] [Accepted: 02/28/2016] [Indexed: 11/17/2022]
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Miksys N, Cygler JE, Caudrelier JM, Thomson RM. Patient-specific Monte Carlo dose calculations for (103)Pd breast brachytherapy. Phys Med Biol 2016; 61:2705-29. [PMID: 26976478 DOI: 10.1088/0031-9155/61/7/2705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This work retrospectively investigates patient-specific Monte Carlo (MC) dose calculations for (103)Pd permanent implant breast brachytherapy, exploring various necessary assumptions for deriving virtual patient models: post-implant CT image metallic artifact reduction (MAR), tissue assignment schemes (TAS), and elemental tissue compositions. Three MAR methods (thresholding, 3D median filter, virtual sinogram) are applied to CT images; resulting images are compared to each other and to uncorrected images. Virtual patient models are then derived by application of different TAS ranging from TG-186 basic recommendations (mixed adipose and gland tissue at uniform literature-derived density) to detailed schemes (segmented adipose and gland with CT-derived densities). For detailed schemes, alternate mass density segmentation thresholds between adipose and gland are considered. Several literature-derived elemental compositions for adipose, gland and skin are compared. MC models derived from uncorrected CT images can yield large errors in dose calculations especially when used with detailed TAS. Differences in MAR method result in large differences in local doses when variations in CT number cause differences in tissue assignment. Between different MAR models (same TAS), PTV [Formula: see text] and skin [Formula: see text] each vary by up to 6%. Basic TAS (mixed adipose/gland tissue) generally yield higher dose metrics than detailed segmented schemes: PTV [Formula: see text] and skin [Formula: see text] are higher by up to 13% and 9% respectively. Employing alternate adipose, gland and skin elemental compositions can cause variations in PTV [Formula: see text] of up to 11% and skin [Formula: see text] of up to 30%. Overall, AAPM TG-43 overestimates dose to the PTV ([Formula: see text] on average 10% and up to 27%) and underestimates dose to the skin ([Formula: see text] on average 29% and up to 48%) compared to the various MC models derived using the post-MAR CT images studied herein. The considerable differences between TG-43 and MC models underline the importance of patient-specific MC dose calculations for permanent implant breast brachytherapy. Further, the sensitivity of these MC dose calculations due to necessary assumptions illustrates the importance of developing a consensus modelling approach.
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Affiliation(s)
- N Miksys
- Department of Physics, Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, ON, Canada
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Mashouf S, Fleury E, Lai P, Merino T, Lechtman E, Kiss A, McCann C, Pignol JP. Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning. Int J Radiat Oncol Biol Phys 2015; 94:816-23. [PMID: 26972654 DOI: 10.1016/j.ijrobp.2015.12.354] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 11/07/2015] [Accepted: 12/14/2015] [Indexed: 11/30/2022]
Abstract
PURPOSE The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). METHODS AND MATERIALS Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43 dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. RESULTS Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V100 and V90 are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. CONCLUSIONS The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases.
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Affiliation(s)
- Shahram Mashouf
- Medical Biophysics Department, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario, Canada
| | - Emmanuelle Fleury
- Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario, Canada
| | - Priscilla Lai
- Medical Biophysics Department, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Tomas Merino
- Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario, Canada; Radiotherapy Unit, School of Medicine, Departamento de Hemato-oncologia, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Eli Lechtman
- Medical Biophysics Department, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Alex Kiss
- Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Claire McCann
- Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario, Canada
| | - Jean-Philippe Pignol
- Medical Biophysics Department, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Sunnybrook Odette Cancer Centre, Toronto, Ontario, Canada; Radiation Oncology Department, Erasmus Medical Center, Cancer Institute, Rotterdam, the Netherlands.
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Miksys N, Xu C, Beaulieu L, Thomson RM. Development of virtual patient models for permanent implant brachytherapy Monte Carlo dose calculations: interdependence of CT image artifact mitigation and tissue assignment. Phys Med Biol 2015. [PMID: 26216174 DOI: 10.1088/0031-9155/60/15/6039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This work investigates and compares CT image metallic artifact reduction (MAR) methods and tissue assignment schemes (TAS) for the development of virtual patient models for permanent implant brachytherapy Monte Carlo (MC) dose calculations. Four MAR techniques are investigated to mitigate seed artifacts from post-implant CT images of a homogeneous phantom and eight prostate patients: a raw sinogram approach using the original CT scanner data and three methods (simple threshold replacement (STR), 3D median filter, and virtual sinogram) requiring only the reconstructed CT image. Virtual patient models are developed using six TAS ranging from the AAPM-ESTRO-ABG TG-186 basic approach of assigning uniform density tissues (resulting in a model not dependent on MAR) to more complex models assigning prostate, calcification, and mixtures of prostate and calcification using CT-derived densities. The EGSnrc user-code BrachyDose is employed to calculate dose distributions. All four MAR methods eliminate bright seed spot artifacts, and the image-based methods provide comparable mitigation of artifacts compared with the raw sinogram approach. However, each MAR technique has limitations: STR is unable to mitigate low CT number artifacts, the median filter blurs the image which challenges the preservation of tissue heterogeneities, and both sinogram approaches introduce new streaks. Large local dose differences are generally due to differences in voxel tissue-type rather than mass density. The largest differences in target dose metrics (D90, V100, V150), over 50% lower compared to the other models, are when uncorrected CT images are used with TAS that consider calcifications. Metrics found using models which include calcifications are generally a few percent lower than prostate-only models. Generally, metrics from any MAR method and any TAS which considers calcifications agree within 6%. Overall, the studied MAR methods and TAS show promise for further retrospective MC dose calculation studies for various permanent implant brachytherapy treatments.
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Affiliation(s)
- N Miksys
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, ON
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Hueso-González F, Vijande J, Ballester F, Perez-Calatayud J, Siebert FA. A simple analytical method for heterogeneity corrections in low dose rate prostate brachytherapy. Phys Med Biol 2015; 60:5455-69. [PMID: 26118956 DOI: 10.1088/0031-9155/60/14/5455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In low energy brachytherapy, the presence of tissue heterogeneities contributes significantly to the discrepancies observed between treatment plan and delivered dose. In this work, we present a simplified analytical dose calculation algorithm for heterogeneous tissue. We compare it with Monte Carlo computations and assess its suitability for integration in clinical treatment planning systems. The algorithm, named as RayStretch, is based on the classic equivalent path length method and TG-43 reference data. Analytical and Monte Carlo dose calculations using Penelope2008 are compared for a benchmark case: a prostate patient with calcifications. The results show a remarkable agreement between simulation and algorithm, the latter having, in addition, a high calculation speed. The proposed analytical model is compatible with clinical real-time treatment planning systems based on TG-43 consensus datasets for improving dose calculation and treatment quality in heterogeneous tissue. Moreover, the algorithm is applicable for any type of heterogeneities.
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Affiliation(s)
- Fernando Hueso-González
- Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Dr. Moliner 50, E-46100 Burjassot, Spain
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37
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Collins Fekete CA, Plamondon M, Martin AG, Vigneault É, Verhaegen F, Beaulieu L. Calcifications in low-dose rate prostate seed brachytherapy treatment: post-planning dosimetry and predictive factors. Radiother Oncol 2015; 114:339-44. [PMID: 25702862 DOI: 10.1016/j.radonc.2015.01.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 01/21/2015] [Accepted: 01/28/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND PURPOSE The brachytherapy dose algorithm of the American Association of Physicists in Medicine Task Group (TG) Report 43 overrides all tissue materials with water. In reality, dose discrepancies will occur around tissue calcifications. This study investigates these perturbations in low dose rate prostate brachytherapy dosimetry. MATERIALS AND METHODS 43 cancer patients with prostatic calcifications are identified. Geant4 Monte Carlo (MC) simulations are made with materials assigned based on TG186 recommendations. Five dose calculation scenarios are presented: MC in water (MCW), MCW with calcifications, (MCCA), MCCA with seeds (MCCASEED) and full tissue definition and seeds with dose to medium in medium (FMC) and dose to water in medium (FMC-Dw,m). RESULTS The mean FMC prostate D90 (V100) difference relative to TG43 is -6.4% (range [-1.8, -14.1]) (-2.6% [-0.3, -6.7]). For MCCA we obtained -3.9% [-1.0, -8.7] (-1.5% [-0.2, -4.1]). The mean urethra D10 difference is -4.5% [-1.3, -9.9] for FMC, -2.4% [-0.7, -5.1] with MCCA. FMC-Dw,m D90 has a -0.45% smaller dose difference than FMC on average. The calcification/prostate volume ratio is a good predictor of dose perturbation (R(2)=0.75). CONCLUSION Based on these results, calcifications alter the dose coverage and may have severe dose perturbation that requires recalculation.
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Affiliation(s)
- Charles-Antoine Collins Fekete
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
| | - Mathieu Plamondon
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada.
| | - André-Guy Martin
- Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
| | - Éric Vigneault
- Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
| | - Frank Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands; Medical Physics Unit, McGill University Health Centre and Department of Oncology, McGill University, Montréal, Québec, Canada.
| | - Luc Beaulieu
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
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Sarrut D, Bardiès M, Boussion N, Freud N, Jan S, Létang JM, Loudos G, Maigne L, Marcatili S, Mauxion T, Papadimitroulas P, Perrot Y, Pietrzyk U, Robert C, Schaart DR, Visvikis D, Buvat I. A review of the use and potential of the GATE Monte Carlo simulation code for radiation therapy and dosimetry applications. Med Phys 2015; 41:064301. [PMID: 24877844 DOI: 10.1118/1.4871617] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same framework is emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.
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Affiliation(s)
- David Sarrut
- Université de Lyon, CREATIS; CNRS UMR5220; Inserm U1044; INSA-Lyon; Université Lyon 1; Centre Léon Bérard, France
| | - Manuel Bardiès
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | | | - Nicolas Freud
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon, France
| | | | - Jean-Michel Létang
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon, France
| | - George Loudos
- Department of Medical Instruments Technology, Technological Educational Institute of Athens, Athens 12210, Greece
| | - Lydia Maigne
- UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière, France
| | - Sara Marcatili
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | - Thibault Mauxion
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | - Panagiotis Papadimitroulas
- Department of Biomedical Engineering, Technological Educational Institute of Athens, 12210, Athens, Greece
| | - Yann Perrot
- UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière, France
| | - Uwe Pietrzyk
- Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany and Fachbereich für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal, Germany
| | - Charlotte Robert
- IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, Orsay 91406, France
| | - Dennis R Schaart
- Delft University of Technology, Faculty of Applied Sciences, Radiation Science and Technology Department, Delft Mekelweg 15, 2629 JB Delft, The Netherlands
| | | | - Irène Buvat
- IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, 91406 Orsay, France and CEA/DSV/I2BM/SHFJ, 91400 Orsay, France
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Gregory KJ, Pattison JE, Bibbo G. Measurement uncertainty analysis of low-dose-rate prostate seed brachytherapy: post-implant dosimetry. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 38:71-81. [DOI: 10.1007/s13246-014-0325-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 12/20/2014] [Indexed: 11/30/2022]
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Karimi Jashni H, Safigholi H, Meigooni AS. Influences of spherical phantom heterogeneities on dosimetric charactristics of miniature electronic brachytherapy X-ray sources: Monte Carlo study. Appl Radiat Isot 2015; 95:108-113. [DOI: 10.1016/j.apradiso.2014.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 07/16/2014] [Accepted: 10/15/2014] [Indexed: 10/24/2022]
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Fonseca GP, Reniers B, Landry G, White S, Bellezzo M, Antunes PC, de Sales CP, Welteman E, Yoriyaz H, Verhaegen F. A medical image-based graphical platform—Features, applications and relevance for brachytherapy. Brachytherapy 2014; 13:632-9. [DOI: 10.1016/j.brachy.2014.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 01/08/2023]
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42
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Investigation of interseed attenuation and tissue composition effects in 125I seed implant prostate brachytherapy. Brachytherapy 2014; 13:603-10. [DOI: 10.1016/j.brachy.2014.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/03/2014] [Accepted: 04/11/2014] [Indexed: 11/24/2022]
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Oliveira SM, Teixeira NJ, Fernandes L, Teles P, Vieira G, Vaz P. Tissue composition and density impact on the clinical parameters for (125)I prostate implants dosimetry. Phys Med 2014; 30:799-808. [PMID: 25239870 DOI: 10.1016/j.ejmp.2014.06.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 06/18/2014] [Accepted: 06/20/2014] [Indexed: 10/24/2022] Open
Abstract
The MCNPX code was used to calculate the TG-43U1 recommended parameters in water and prostate tissue in order to quantify the dosimetric impact in 30 patients treated with (125)I prostate implants when replacing the TG-43U1 formalism parameters calculated in water by a prostate-like medium in the planning system (PS) and to evaluate the uncertainties associated with Monte Carlo (MC) calculations. The prostate density was obtained from the CT of 100 patients with prostate cancer. The deviations between our results for water and the TG-43U1 consensus dataset values were -2.6% for prostate V100, -13.0% for V150, and -5.8% for D90; -2.0% for rectum V100, and -5.1% for D0.1; -5.0% for urethra D10, and -5.1% for D30. The same differences between our water and prostate results were all under 0.3%. Uncertainties estimations were up to 2.9% for the gL(r) function, 13.4% for the F(r,θ) function and 7.0% for Λ, mainly due to seed geometry uncertainties. Uncertainties in extracting the TG-43U1 parameters in the MC simulations as well as in the literature comparison are of the same order of magnitude as the differences between dose distributions computed for water and prostate-like medium. The selection of the parameters for the PS should be done carefully, as it may considerably affect the dose distributions. The seeds internal geometry uncertainties are a major limiting factor in the MC parameters deduction.
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Affiliation(s)
- Susana Maria Oliveira
- Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria, 130, 1169-056 Lisbon, Portugal; Quadrantes Faro - Unidade de Radioterapia do Algarve, Rua da Associação Oncológica do Algarve, 8000-316 Faro, Portugal; MedicalConsult, SA, Campo Grande, 56-8°A, 1700-093 Lisbon, Portugal.
| | - Nuno José Teixeira
- Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria, 130, 1169-056 Lisbon, Portugal; Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, lote 4.69.01, 1900-096 Lisbon, Portugal
| | - Lisete Fernandes
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, lote 4.69.01, 1900-096 Lisbon, Portugal; Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal; Centro de Biodiversidade, Genómica Integrativa e Funcional, Faculdade de Ciências, Universidade de Lisboa, Edifício ICAT, Campus FCUL, Campo Grande, 1740-016 Lisbon, Portugal
| | - Pedro Teles
- IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2695-006 Bobadela LRS, Portugal
| | - Guy Vieira
- Quadrantes Faro - Unidade de Radioterapia do Algarve, Rua da Associação Oncológica do Algarve, 8000-316 Faro, Portugal
| | - Pedro Vaz
- IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2695-006 Bobadela LRS, Portugal
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Mashouf S, Lechtman E, Lai P, Keller BM, Karotki A, Beachey DJ, Pignol JP. Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images. Phys Med Biol 2014; 59:5305-16. [PMID: 25146446 DOI: 10.1088/0031-9155/59/18/5305] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 [Formula: see text] formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.
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Affiliation(s)
- S Mashouf
- Medical Biophysics Department, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N3M5, Canada
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Evans JD, Whiting BR, O'Sullivan JA, Politte DG, Klahr PH, Yu Y, Williamson JF. Prospects for in vivo estimation of photon linear attenuation coefficients using postprocessing dual-energy CT imaging on a commercial scanner: comparison of analytic and polyenergetic statistical reconstruction algorithms. Med Phys 2014; 40:121914. [PMID: 24320525 DOI: 10.1118/1.4828787] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Accurate patient-specific photon cross-section information is needed to support more accurate model-based dose calculation for low energy photon-emitting modalities in medicine such as brachytherapy and kilovoltage x-ray imaging procedures. A postprocessing dual-energy CT (pDECT) technique for noninvasive in vivo estimation of photon linear attenuation coefficients has been experimentally implemented on a commercial CT scanner and its accuracy assessed in idealized phantom geometries. METHODS Eight test materials of known composition and density were used to compare pDECT-estimated linear attenuation coefficients to NIST reference values over an energy range from 10 keV to 1 MeV. As statistical image reconstruction (SIR) has been shown to reconstruct images with less random and systematic error than conventional filtered backprojection (FBP), the pDECT technique was implemented with both an in-house polyenergetic SIR algorithm, alternating minimization (AM), as well as a conventional FBP reconstruction algorithm. Improvement from increased spectral separation was also investigated by filtering the high-energy beam with an additional 0.5 mm of tin. The law of propagated uncertainty was employed to assess the sensitivity of the pDECT process to errors in reconstructed images. RESULTS Mean pDECT-estimated linear attenuation coefficients for the eight test materials agreed within 1% of NIST reference values for energies from 1 MeV down to 30 keV, with mean errors rising to between 3% and 6% at 10 keV, indicating that the method is unbiased when measurement and calibration phantom geometries are matched. Reconstruction with FBP and AM algorithms conferred similar mean pDECT accuracy. However, single-voxel pDECT estimates reconstructed on a 1 × 1 × 3 mm(3) grid are shown to be highly sensitive to reconstructed image uncertainty; in some cases pDECT attenuation coefficient estimates exhibited standard deviations on the order of 20% around the mean. Reconstruction with the statistical AM algorithm led to standard deviations roughly 40% to 60% less than FBP reconstruction. Additional tin filtration of the high energy beam exhibits similar pDECT estimation accuracy as the unfiltered beam, even when scanning with only 25% of the dose. Using the law of propagated uncertainty, low Z materials are found to be more sensitive to image reconstruction errors than high Z materials. Furthermore, it is estimated that reconstructed CT image uncertainty must be limited to less than 0.25% to achieve a target linear-attenuation coefficient estimation uncertainty of 3% at 28 keV. CONCLUSIONS That pDECT supports mean linear attenuation coefficient measurement accuracies of 1% of reference values for energies greater than 30 keV is encouraging. However, the sensitivity of the pDECT measurements to noise and systematic errors in reconstructed CT images warrants further investigation in more complex phantom geometries. The investigated statistical reconstruction algorithm, AM, reduced random measurement uncertainty relative to FBP owing to improved noise performance. These early results also support efforts to increase DE spectral separation, which can further reduce the pDECT sensitivity to measurement uncertainty.
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Affiliation(s)
- Joshua D Evans
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298
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Hünemohr N, Paganetti H, Greilich S, Jäkel O, Seco J. Tissue decomposition from dual energy CT data for MC based dose calculation in particle therapy. Med Phys 2014; 41:061714. [PMID: 24877809 PMCID: PMC4032427 DOI: 10.1118/1.4875976] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 04/23/2014] [Accepted: 04/27/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors describe a novel method of predicting mass density and elemental mass fractions of tissues from dual energy CT (DECT) data for Monte Carlo (MC) based dose planning. METHODS The relative electron density ϱ(e) and effective atomic number Z(eff) are calculated for 71 tabulated tissue compositions. For MC simulations, the mass density is derived via one linear fit in the ϱ(e) that covers the entire range of tissue compositions (except lung tissue). Elemental mass fractions are predicted from the ϱ(e) and the Z(eff) in combination. Since particle therapy dose planning and verification is especially sensitive to accurate material assignment, differences to the ground truth are further analyzed for mass density, I-value predictions, and stopping power ratios (SPR) for ions. Dose studies with monoenergetic proton and carbon ions in 12 tissues which showed the largest differences of single energy CT (SECT) to DECT are presented with respect to range uncertainties. The standard approach (SECT) and the new DECT approach are compared to reference Bragg peak positions. RESULTS Mean deviations to ground truth in mass density predictions could be reduced for soft tissue from (0.5±0.6)% (SECT) to (0.2±0.2)% with the DECT method. Maximum SPR deviations could be reduced significantly for soft tissue from 3.1% (SECT) to 0.7% (DECT) and for bone tissue from 0.8% to 0.1%. Mean I-value deviations could be reduced for soft tissue from (1.1±1.4%, SECT) to (0.4±0.3%) with the presented method. Predictions of elemental composition were improved for every element. Mean and maximum deviations from ground truth of all elemental mass fractions could be reduced by at least a half with DECT compared to SECT (except soft tissue hydrogen and nitrogen where the reduction was slightly smaller). The carbon and oxygen mass fraction predictions profit especially from the DECT information. Dose studies showed that most of the 12 selected tissues would profit significantly (up to 2.2%) from DECT material decomposition with no noise present. The ϱ(e) associated with an absolute noise of ±0.01 and Z(eff) associated with an absolute noise of ±0.2 resulted in ±10% standard variation in the carbon and oxygen mass fraction prediction. CONCLUSIONS Accurate stopping power prediction is mainly determined by the correct mass density prediction. Theoretical improvements in range predictions with DECT data in the order of 0.1%-2.1% were observed. Further work is needed to quantify the potential improvements from DECT compared to SECT in measured image data associated with artifacts and noise.
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Affiliation(s)
- Nora Hünemohr
- Medical Physics in Radiation Oncology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Steffen Greilich
- Medical Physics in Radiation Oncology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Oliver Jäkel
- Medical Physics in Radiation Oncology, German Cancer Research Center, 69120 Heidelberg, Germany and Department of Radiation Oncology and Radiation Therapy, University Hospital of Heidelberg, 69120 Heidelberg, Germany
| | - Joao Seco
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
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White SA, Landry G, Fonseca GP, Holt R, Rusch T, Beaulieu L, Verhaegen F, Reniers B. Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source. Med Phys 2014; 41:061701. [DOI: 10.1118/1.4873319] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Oliveira SM, Teixeira NJ, Fernandes L, Teles P, Vaz P. Dosimetric effect of tissue heterogeneity for (125)I prostate implants. Rep Pract Oncol Radiother 2014; 19:392-8. [PMID: 25337412 DOI: 10.1016/j.rpor.2014.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/26/2013] [Accepted: 03/19/2014] [Indexed: 11/29/2022] Open
Abstract
AIM To use Monte Carlo (MC) together with voxel phantoms to analyze the tissue heterogeneity effect in the dose distributions and equivalent uniform dose (EUD) for (125)I prostate implants. BACKGROUND Dose distribution calculations in low dose-rate brachytherapy are based on the dose deposition around a single source in a water phantom. This formalism does not take into account tissue heterogeneities, interseed attenuation, or finite patient dimensions effects. Tissue composition is especially important due to the photoelectric effect. MATERIALS AND METHODS The computed tomographies (CT) of two patients with prostate cancer were used to create voxel phantoms for the MC simulations. An elemental composition and density were assigned to each structure. Densities of the prostate, vesicles, rectum and bladder were determined through the CT electronic densities of 100 patients. The same simulations were performed considering the same phantom as pure water. Results were compared via dose-volume histograms and EUD for the prostate and rectum. RESULTS The mean absorbed doses presented deviations of 3.3-4.0% for the prostate and of 2.3-4.9% for the rectum, when comparing calculations in water with calculations in the heterogeneous phantom. In the calculations in water, the prostate D 90 was overestimated by 2.8-3.9% and the rectum D 0.1cc resulted in dose differences of 6-8%. The EUD resulted in an overestimation of 3.5-3.7% for the prostate and of 7.7-8.3% for the rectum. CONCLUSIONS The deposited dose was consistently overestimated for the simulation in water. In order to increase the accuracy in the determination of dose distributions, especially around the rectum, the introduction of the model-based algorithms is recommended.
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Key Words
- AAPM TG, American Association of Physicists in Medicine Task Group
- Brachytherapy
- CT, computerized tomography
- DVH, dose–volume histogram
- EBRT, external beam radiotherapy
- EUD, equivalent uniform dose
- HT, heterogeneous
- LDRBT, low dose-rate brachytherapy
- MBDCA, model-based dose calculation algorithm
- MC, Monte Carlo
- Model-based calculation algorithms
- Monte Carlo
- NTCP, normal tissue complication probability
- OAR, organ at risk
- PS, planning system
- Prostate cancer
- TCP, tumor control probability (TCP)
- Tissue heterogeneity
- W, water
- dDVH, differential dose–volume histogram
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Affiliation(s)
- Susana Maria Oliveira
- Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria, 130, 1169-056 Lisbon, Portugal ; Quadrantes Faro - Unidade de Radioterapia do Algarve, Rua da Associação Oncológica do Algarve, 8000-316 Faro, Portugal ; MedicalConsult, SA, Campo Grande, 56-8°A, 1700-093 Lisbon, Portugal
| | - Nuno José Teixeira
- Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria, 130, 1169-056 Lisbon, Portugal ; Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, lote 4.69.01, 1900-096 Lisbon, Portugal
| | - Lisete Fernandes
- Escola Superior de Tecnologia da Saúde de Lisboa, Instituto Politécnico de Lisboa, Av. D. João II, lote 4.69.01, 1900-096 Lisbon, Portugal ; Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal ; Centro de Biodiversidade, Genómica Integrativa e Funcional, Faculdade de Ciências, Universidade de Lisboa, Edifício ICAT, Campus FCUL, Campo Grande, 1740-016 Lisbon, Portugal
| | - Pedro Teles
- IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2695-006 Bobadela LRS, Portugal
| | - Pedro Vaz
- IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2695-006 Bobadela LRS, Portugal
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Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C. Advances in kilovoltage x-ray beam dosimetry. Phys Med Biol 2014; 59:R183-231. [DOI: 10.1088/0031-9155/59/6/r183] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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50
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Sutherland JGH, Miksys N, Furutani KM, Thomson RM. Metallic artifact mitigation and organ-constrained tissue assignment for Monte Carlo calculations of permanent implant lung brachytherapy. Med Phys 2013; 41:011712. [DOI: 10.1118/1.4851555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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