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Terashima S, Sano J, Osanai M, Toshima K, Ohuchi K, Hosokawa Y. Monte Carlo simulations of organ and effective doses and dose-length product for dental cone-beam CT. Oral Radiol 2024; 40:37-48. [PMID: 37597068 DOI: 10.1007/s11282-023-00705-7] [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: 03/14/2023] [Accepted: 08/03/2023] [Indexed: 08/21/2023]
Abstract
OBJECTIVES The use of dental cone-beam CT (CBCT) has increased in recent years. We aimed to calculate the organ and effective doses in dental CBCT using Monte Carlo simulation (MCS) and to correlate the effective dose with the dose-length product (DLP), which is a radiation dose index. METHODS Organ and effective doses were calculated by MCS using the adult male and female reference phantoms of the International Commission on Radiological Protection publication 110 in a half-rotation scan of the CBCT scanner Veraviewepocs 3Df. The simulations were performed by setting nine protocols in combination with the field-of-view (FOV) and imaging region. In addition, DLPs were calculated by MCS using the virtual CT Dose Index (CTDI) and CBCT phantoms, with the same protocol. RESULTS The effective doses were 55 and 195 μSv at the minimum FOV of Φ40 × H40 mm and maximum FOV of Φ 80 × H80 mm, respectively. The organs with the major contribution to the effective dose were the red bone marrow (11.0‒12.8%), thyroid gland (4.0‒12.7%), salivary gland (21.8‒33.2%), and remaining tissues (35.1‒45.7%). Positive correlations were obtained between the effective dose and calculated DLP using the CTDI and CBCT phantoms. CONCLUSIONS Organ and effective doses for each protocol of dental CBCT could be estimated using MCS. There was a positive correlation between the effective dose and DLP, suggesting that DLP can be used to estimate the effective dose of CBCT.
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Affiliation(s)
- Shingo Terashima
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1, Hon-cho, Hirosaki, 036-8564, Japan.
| | - Junta Sano
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Kita15, Nishi7, Kita-ku, Sapporo, 060-8638, Japan
| | - Minoru Osanai
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1, Hon-cho, Hirosaki, 036-8564, Japan
| | - Keisuke Toshima
- Department of Radiology, Akita University Hospital, 44-2, Hiroomote Hasunuma, Akita, 010-8543, Japan
| | - Kentaro Ohuchi
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Health Sciences University of Hokkaido, Tobetsu-Cho, Ishikari-gun, Hokkaido, 061-0293, Japan
| | - Yoichiro Hosokawa
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1, Hon-cho, Hirosaki, 036-8564, Japan
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Monte-Carlo techniques for radiotherapy applications II: equipment and source modelling, dose calculations and radiobiology. JOURNAL OF RADIOTHERAPY IN PRACTICE 2023. [DOI: 10.1017/s1460396923000080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Abstract
Introduction:
This is the second of two papers giving an overview of the use of Monte-Carlo techniques for radiotherapy applications.
Methods:
The first paper gave an introduction and introduced some of the codes that are available to the user wishing to model the different aspects of radiotherapy treatment. It also aims to serve as a useful companion to a curated collection of papers on Monte-Carlo that have been published in this journal.
Results and Conclusions:
This paper focuses on the application of Monte-Carlo to specific problems in radiotherapy. These include radiotherapy and imaging beam production, brachytherapy, phantom and patient dosimetry, detector modelling and track structure calculations for micro-dosimetry, nano-dosimetry and radiobiology.
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Brooks J, Zuro D, Song JY, Madabushi SS, Sanchez JF, Guha C, Kortylewski M, Chen BT, Gupta K, Storme G, Froelich J, Hui SK. Longitudinal Preclinical Imaging Characterizes Extracellular Drug Accumulation After Radiation Therapy in the Healthy and Leukemic Bone Marrow Vascular Microenvironment. Int J Radiat Oncol Biol Phys 2022; 112:951-963. [PMID: 34767936 PMCID: PMC9038217 DOI: 10.1016/j.ijrobp.2021.10.146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 08/24/2021] [Accepted: 10/22/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE Recent initial findings suggest that radiation therapy improves blood perfusion and cellular chemotherapy uptake in mice with leukemia. However, the ability of radiation therapy to influence drug accumulation in the extracellular bone marrow tissue is unknown, due in part to a lack of methodology. This study developed longitudinal quantitative multiphoton microscopy (L-QMPM) to characterize the bone marrow vasculature (BMV) and drug accumulation in the extracellular bone marrow tissue before and after radiation therapy in mice bearing leukemia. METHODS AND MATERIALS We developed a longitudinal window implant for L-QMPM imaging of the calvarium BMV before, 2 days after, and 5 days after total body irradiation (TBI). Live time-lapsed images of a fluorescent drug surrogate were used to obtain measurements, including tissue wash-in slope (WIStissue) to measure extracellular drug accumulation. We performed L-QMPM imaging on healthy C57BL/6 (WT) mice, as well as mice bearing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). RESULTS Implants had no effects on calvarium dose, and parameters for wild-type untreated mice were stable during imaging. We observed decreased vessel diameter, vessel blood flow, and WIStissue with the onset of AML and ALL. Two to 10 Gy TBI increased WIStissue and vessel diameter 2 days after radiation therapy in all 3 groups of mice and increased single-vessel blood flow in mice bearing ALL and AML. Increased WIStissue was observed 5 days after 10 Gy TBI or 4 Gy split-dose TBI (2 treatments of 2 Gy spaced 3 days apart). CONCLUSIONS L-QMPM provides stable functional assessments of the BMV. Nonmyeloablative and myeloablative TBI increases extracellular drug accumulation in the leukemic bone marrow 2 to 5 days posttreatment, likely through improved blood perfusion and drug exchange from the BMV to the extravascular tissue. Our data show that neo-adjuvant TBI at doses from 2 Gy to 10 Gy conditions the BMV to improve drug transport to the bone marrow.
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Affiliation(s)
- Jamison Brooks
- Department of Radiation Oncology, City of Hope, Duarte, California; Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Darren Zuro
- Department of Radiation Oncology, City of Hope, Duarte, California; Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Joo Y Song
- Department of Pathology, City of Hope, Duarte, California
| | | | - James F Sanchez
- Beckman Research Institute of City of Hope, Duarte, California
| | - Chandan Guha
- Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York
| | - Marcin Kortylewski
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope, Duarte, California
| | - Bihong T Chen
- Department of Diagnostic Radiology, City of Hope Medical Center, Duarte, California
| | - Kalpna Gupta
- Hematology/Oncology, Department of Medicine, University of California, Irvine and Southern California Institute for Research and Education, VA Medical Center, North Hills, California; Division of Hematology, Oncology and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Guy Storme
- Department of Radiotherapy, UZ Brussel, Jette, Belgium
| | - Jerry Froelich
- Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Susanta K Hui
- Department of Radiation Oncology, City of Hope, Duarte, California; Beckman Research Institute of City of Hope, Duarte, California.
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Heidarloo N, Mahmoud Reza Aghamiri S, Saghamanesh S, Azma Z, Alaei P. A novel analytical method for computing dose from kilovoltage beams used in Image-Guided radiation therapy. Phys Med 2022; 96:54-61. [PMID: 35219962 DOI: 10.1016/j.ejmp.2022.02.020] [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: 11/05/2021] [Revised: 02/12/2022] [Accepted: 02/20/2022] [Indexed: 10/19/2022] Open
Abstract
PURPOSE A modified convolution/superposition algorithm is proposed to compute dose from the kilovoltage beams used in IGRT. The algorithm uses material-specific energy deposition kernels instead of water-energy deposition kernels. METHODS Monte Carlo simulation was used to model the Elekta XVI unit and determine dose deposition characteristics of its kilovoltage beams. The dosimetric results were compared with ion chamber measurements. The dose from the kilovoltage beams was then computed using convolution/superposition along with material-specific energy deposition kernels and compared with Monte Carlo and measurements. The material-specific energy deposition kernels were previously generated using Monte Carlo. RESULTS The obtained gamma indices (using 2%/2mm criteria for 95% of points) were lower than 1 in almost all instances which indicates good agreement between simulated and measured depth doses and profiles. The comparisons of the algorithm with measurements in a homogeneous solid water slab phantom, and that with Monte Carlo in a head and neck CT dataset produced acceptable results. The calculated point doses were within 4.2% of measurements in the homogeneous phantom. Gamma analysis of the calculated vs. Monte Carlo simulations in the head and neck phantom resulted in 94% of points passing with a 2%/2mm criteria. CONCLUSIONS The proposed method offers sufficient accuracy in kilovoltage beams dose calculations and has the potential to supplement the conventional megavoltage convolution/superposition algorithms for dose calculations in low energy range.
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Affiliation(s)
- Nematollah Heidarloo
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran
| | | | - Somayeh Saghamanesh
- Center for X-ray Analytics, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Zohreh Azma
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran; Erfan Radiation Oncology Center, Erfan-Niyayesh hospital, Iran University of Medical Science, Tehran, Iran
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, MN, USA
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Costa PR, Nersissian DY, Umisedo NK, Gonzales AHL, Fernández-Varea JM. A comprehensive Monte Carlo study of CT dose metrics proposed by the AAPM Reports 111 and 200. Med Phys 2021; 49:201-218. [PMID: 34800303 DOI: 10.1002/mp.15306] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 09/22/2021] [Accepted: 10/10/2021] [Indexed: 11/11/2022] Open
Abstract
PURPOSE A Monte Carlo (MC) modeling of single axial and helical CT scan modes has been developed to compute single and accumulated dose distributions. The radiation emission characteristics of an MDCT scanner has been modeled and used to evaluate the dose deposition in infinitely long head and body PMMA phantoms. The simulated accumulated dose distributions determined the approach to equilibrium function, H(L). From these H ( L ) curves, dose-related information was calculated for different head and body clinical protocols. METHODS The PENELOPE/penEasy package has been used to model the single axial and helical procedures and the radiation transport of photons and electrons in the phantoms. The bowtie filters, heel effect, focal-spot angle, and fan-beam geometry were incorporated. Head and body protocols with different pitch values were modeled for x-ray spectra corresponding to 80, 100, 120, and 140 kV. The analytical formulation for the single dose distributions and experimental measurements of single and accumulated dose distributions were employed to validate the MC results. The experimental dose distributions were measured with OSLDs and a thimble ion chamber inserted into PMMA phantoms. Also, the experimental values of the C T D I 100 along the center and peripheral axes of the CTDI phantom served to calibrate the simulated single and accumulated dose distributions. RESULTS The match of the simulated dose distributions with the reference data supports the correct modeling of the heel effect and the radiation transport in the phantom material reflected in the tails of the dose distributions. The validation of the x-ray source model was done comparing the CTDI ratios between simulated, measured and CTDosimetry data. The average difference of these ratios for head and body protocols between the simulated and measured data was in the range of 13-17% and between simulated and CTDosimetry data varied 10-13%. The distributions of simulated doses and those measured with the thimble ion chamber are compatible within 3%. In this study, it was demonstrated that the efficiencies of the C T D I 100 measurements in head phantoms with nT = 20 mm and 120 kV are 80.6% and 87.8% at central and peripheral axes, respectively. In the body phantoms with n T = 40 mm and 120 kV, the efficiencies are 56.5% and 86.2% at central and peripheral axes, respectively. In general terms, the clinical parameters such as pitch, beam intensity, and voltage affect the Deq values with the increase of the pitch decreasing the Deq and the beam intensity and the voltage increasing its value. The H(L) function does not change with the pitch values, but depends on the phantom axis (central or peripheral). CONCLUSIONS The computation of the pitch-equilibrium dose product, D ̂ eq , evidenced the limitations of the C T D I 100 method to determine the dose delivered by a CT scanner. Therefore, quantities derived from the C T D I 100 propagate this limitation. The developed MC model shows excellent compatibility with both measurements and literature quantities defined by AAPM Reports 111 and 200. These results demonstrate the robustness and versatility of the proposed modeling method.
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Affiliation(s)
- Paulo R Costa
- Institute of Physics, University of São Paulo, São Paulo, SP, Brazil
| | | | - Nancy K Umisedo
- Institute of Physics, University of São Paulo, São Paulo, SP, Brazil
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Zuro D, Madabushi SS, Brooks J, Chen BT, Goud J, Salhotra A, Song JY, Parra LE, Pierini A, Sanchez JF, Stein A, Malki MA, Kortylewski M, Wong JYC, Alaei P, Froelich J, Storme G, Hui SK. First Multimodal, Three-Dimensional, Image-Guided Total Marrow Irradiation Model for Preclinical Bone Marrow Transplantation Studies. Int J Radiat Oncol Biol Phys 2021; 111:671-683. [PMID: 34119592 DOI: 10.1016/j.ijrobp.2021.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 01/13/2023]
Abstract
PURPOSE Total marrow irradiation (TMI) has significantly advanced radiation conditioning for hematopoietic cell transplantation in hematologic malignancies by reducing conditioning-induced toxicities and improving survival outcomes in relapsed/refractory patients. However, the relapse rate remains high, and the lack of a preclinical TMI model has hindered scientific advancements. To accelerate TMI translation to the clinic, we developed a TMI delivery system in preclinical models. METHODS AND MATERIALS A Precision X-RAD SmART irradiator was used for TMI model development. Images acquired with whole-body contrast-enhanced computed tomography (CT) were used to reconstruct and delineate targets and vital organs for each mouse. Multiple beam and CT-guided Monte Carlo-based plans were performed to optimize doses to the targets and to vary doses to the vital organs. Long-term engraftment and reconstitution potential were evaluated by a congenic bone marrow transplantation (BMT) model and serial secondary BMT, respectively. Donor cell engraftment was measured using noninvasive bioluminescence imaging and flow cytometry. RESULTS Multimodal imaging enabled identification of targets (skeleton and spleen) and vital organs (eg, lungs, gut, liver). In contrast to total body irradiation (TBI), TMI treatment allowed variation of radiation dose exposure to organs relative to the target dose. Dose reduction mirrored that in clinical TMI studies. Similar to TBI, mice treated with different TMI regimens showed full long-term donor engraftment in primary BMT and second serial BMT. The TBI-treated mice showed acute gut damage, which was minimized in mice treated with TMI. CONCLUSIONS A novel multimodal image guided preclinical TMI model is reported here. TMI conditioning maintained long-term engraftment with reconstitution potential and reduced organ damage. Therefore, this TMI model provides a unique opportunity to study the therapeutic benefit of reduced organ damage and BM dose escalation to optimize treatment regimens in BMT and hematologic malignancies.
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Affiliation(s)
- Darren Zuro
- Department of Radiation Oncology, City of Hope Medical Center, Duarte, California
| | | | - Jamison Brooks
- Department of Radiation Oncology, City of Hope Medical Center, Duarte, California
| | - Bihong T Chen
- Department of Diagnostic Radiology, City of Hope Medical Center, Duarte, California
| | - Janagama Goud
- Department of Radiation Oncology, City of Hope Medical Center, Duarte, California
| | - Amandeep Salhotra
- Department of Hematology and HCT, City of Hope Medical Center, Duarte, California
| | - Joo Y Song
- Department of Pathology, City of Hope Medical Center, Duarte, California
| | | | - Antonio Pierini
- Division of Hematology and Clinical Immunology, Department of Medicine, University of Perugia, Perugia, Italy
| | - James F Sanchez
- Beckman Research Institute of City of Hope, Duarte, California
| | - Anthony Stein
- Department of Hematology and HCT, City of Hope Medical Center, Duarte, California
| | - Monzr Al Malki
- Department of Hematology and HCT, City of Hope Medical Center, Duarte, California
| | - Marcin Kortylewski
- Department of Immuno-Oncology, Beckman Research Institute, City of Hope, Duarte, California
| | - Jeffrey Y C Wong
- Department of Radiation Oncology, City of Hope Medical Center, Duarte, California
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Jerry Froelich
- Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Guy Storme
- Department of Radiotherapy UZ Brussels, Brussels, Belgium
| | - Susanta K Hui
- Department of Radiation Oncology, City of Hope Medical Center, Duarte, California; Beckman Research Institute of City of Hope, Duarte, California; Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota.
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Ueno H, Matsubara K, Takemura A, Hizume M, Bou S. Evaluation of the relationship between phantom position and computed tomography dose index in cone beam computed tomography when assuming breast irradiation. J Appl Clin Med Phys 2021; 22:262-267. [PMID: 34048143 PMCID: PMC8200449 DOI: 10.1002/acm2.13282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/21/2021] [Accepted: 04/23/2021] [Indexed: 11/21/2022] Open
Abstract
This study aims to investigate the influence of the phantom position on weighted computed tomography dose index (CTDIw ) in cone beam computed tomography (CBCT) when assuming breast irradiation. Computed tomography dose index (CTDI) was measured by the x-ray volume imaging of CBCT using parameters for image-guided radiation therapy (IGRT) in right breast irradiation. The measurement points of CTDI ranged from 0 (center) to 16 cm in the right-left (RL) direction, and from 0 (center) to 7.5 cm in the anterior-posterior (AP) direction, which assumed right breast irradiation. A nonuniform change exists in the relative value of CTDIw when the phantom deviated from the isocenter of CBCT. The CTDIw was ~30% lower compared with the value at the isocenter of CBCT when the phantom deviated 7.5 and 16 cm at the AP and RL directions, respectively. This study confirmed the influence of the phantom position on the CTDI values of CBCT. The CTDI measured at the isocenter of CBCT overestimates that measured at the irradiation center of the breast.
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Affiliation(s)
- Hiroyuki Ueno
- Department of RadiologyTakaoka City HospitalTakaokaToyamaJapan
- Division of Health Sciences, Graduate School of Medical SciencesKanazawa UniversityKanazawaIshikawaJapan
| | - Kosuke Matsubara
- Division of Health Sciences, Graduate School of Medical SciencesKanazawa UniversityKanazawaIshikawaJapan
| | - Akihiro Takemura
- Division of Health Sciences, Graduate School of Medical SciencesKanazawa UniversityKanazawaIshikawaJapan
| | - Masato Hizume
- Department of RadiologyTakaoka City HospitalTakaokaToyamaJapan
| | - Sayuri Bou
- Department of RadiotherapyTakaoka City HospitalTakaokaToyamaJapan
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Ozaki Y, Watanabe H, Kurabayashi T. Effective dose estimation in cone-beam computed tomography for dental use by Monte-Carlo simulation optimizing calculation numbers using a step-and-shoot method. Dentomaxillofac Radiol 2021; 50:20210084. [PMID: 33929892 DOI: 10.1259/dmfr.20210084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE The objective of this study was to perform effective dose estimation in cone-beam CT for dental use (CBCT) using a Monte-Carlo simulation employing a step-and-shoot method as well as to determine the optimal number of steps. METHODS We simulated 3DX Accuitomo FPD8 as a CBCT model and estimated the effective doses of a large and a small field of view (FOV) examination against the virtual Rando phantom using a particle and heavy ion transport code system. We confirmed the results compared to those from a thermo-luminescence dosemeter (TLD) system in a real phantom and investigated how the reduced angle calculations could be accepted. RESULTS The effective doses of both FOVs estimated with each one degree were almost the same as those estimated from the TLD measurements. Considering the effective doses and the itemized organ doses, simulation with 5° and 10° is acceptable for the large and small FOV, respectively. We tried to compare an effective dose with a large FOV as well as with multiple small FOVs covering the corresponding area and found that the effective dose from six small FOVs was approximately 1.2 times higher than that of the large FOVs. CONCLUSION We successfully performed a Monte-Carlo simulation using a step-and-shoot method and estimated the effective dose in CBCT. Our findings indicate that simulation with 5° or 10° is acceptable based on the FOV size, while a small multiple FOV scan is recommended from a radiation protection viewpoint.
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Affiliation(s)
- Yoshihiro Ozaki
- Department of Oral and Maxillofacial Radiology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroshi Watanabe
- Department of Oral and Maxillofacial Radiology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tohru Kurabayashi
- Department of Oral and Maxillofacial Radiology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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Alizadehsani R, Roshanzamir M, Hussain S, Khosravi A, Koohestani A, Zangooei MH, Abdar M, Beykikhoshk A, Shoeibi A, Zare A, Panahiazar M, Nahavandi S, Srinivasan D, Atiya AF, Acharya UR. Handling of uncertainty in medical data using machine learning and probability theory techniques: a review of 30 years (1991-2020). ANNALS OF OPERATIONS RESEARCH 2021:1-42. [PMID: 33776178 PMCID: PMC7982279 DOI: 10.1007/s10479-021-04006-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/23/2021] [Indexed: 05/17/2023]
Abstract
Understanding the data and reaching accurate conclusions are of paramount importance in the present era of big data. Machine learning and probability theory methods have been widely used for this purpose in various fields. One critically important yet less explored aspect is capturing and analyzing uncertainties in the data and model. Proper quantification of uncertainty helps to provide valuable information to obtain accurate diagnosis. This paper reviewed related studies conducted in the last 30 years (from 1991 to 2020) in handling uncertainties in medical data using probability theory and machine learning techniques. Medical data is more prone to uncertainty due to the presence of noise in the data. So, it is very important to have clean medical data without any noise to get accurate diagnosis. The sources of noise in the medical data need to be known to address this issue. Based on the medical data obtained by the physician, diagnosis of disease, and treatment plan are prescribed. Hence, the uncertainty is growing in healthcare and there is limited knowledge to address these problems. Our findings indicate that there are few challenges to be addressed in handling the uncertainty in medical raw data and new models. In this work, we have summarized various methods employed to overcome this problem. Nowadays, various novel deep learning techniques have been proposed to deal with such uncertainties and improve the performance in decision making.
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Affiliation(s)
- Roohallah Alizadehsani
- Institute for Intelligent Systems Research and Innovations (IISRI), Deakin University, Geelong, Australia
| | - Mohamad Roshanzamir
- Department of Computer Engineering, Faculty of Engineering, Fasa University, 74617-81189 Fasa, Iran
| | - Sadiq Hussain
- System Administrator, Dibrugarh University, Dibrugarh, Assam 786004 India
| | - Abbas Khosravi
- Institute for Intelligent Systems Research and Innovations (IISRI), Deakin University, Geelong, Australia
| | - Afsaneh Koohestani
- Institute for Intelligent Systems Research and Innovations (IISRI), Deakin University, Geelong, Australia
| | | | - Moloud Abdar
- Institute for Intelligent Systems Research and Innovations (IISRI), Deakin University, Geelong, Australia
| | - Adham Beykikhoshk
- Applied Artificial Intelligence Institute, Deakin University, Geelong, Australia
| | - Afshin Shoeibi
- Computer Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran
- Faculty of Electrical and Computer Engineering, Biomedical Data Acquisition Lab, K. N. Toosi University of Technology, Tehran, Iran
| | - Assef Zare
- Faculty of Electrical Engineering, Gonabad Branch, Islamic Azad University, Gonabad, Iran
| | - Maryam Panahiazar
- Institute for Computational Health Sciences, University of California, San Francisco, USA
| | - Saeid Nahavandi
- Institute for Intelligent Systems Research and Innovations (IISRI), Deakin University, Geelong, Australia
| | - Dipti Srinivasan
- Dept. of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576 Singapore
| | - Amir F. Atiya
- Department of Computer Engineering, Faculty of Engineering, Cairo University, Cairo, 12613 Egypt
| | - U. Rajendra Acharya
- Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, Singapore, Singapore
- Department of Biomedical Engineering, School of Science and Technology, Singapore University of Social Sciences, Singapore, Singapore
- Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan
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Jeong H, Ntolkeras G, Alhilani M, Atefi SR, Zöllei L, Fujimoto K, Pourvaziri A, Lev MH, Grant PE, Bonmassar G. Development, validation, and pilot MRI safety study of a high-resolution, open source, whole body pediatric numerical simulation model. PLoS One 2021; 16:e0241682. [PMID: 33439896 PMCID: PMC7806143 DOI: 10.1371/journal.pone.0241682] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
Numerical body models of children are used for designing medical devices, including but not limited to optical imaging, ultrasound, CT, EEG/MEG, and MRI. These models are used in many clinical and neuroscience research applications, such as radiation safety dosimetric studies and source localization. Although several such adult models have been reported, there are few reports of full-body pediatric models, and those described have several limitations. Some, for example, are either morphed from older children or do not have detailed segmentations. Here, we introduce a 29-month-old male whole-body native numerical model, "MARTIN", that includes 28 head and 86 body tissue compartments, segmented directly from the high spatial resolution MRI and CT images. An advanced auto-segmentation tool was used for the deep-brain structures, whereas 3D Slicer was used to segment the non-brain structures and to refine the segmentation for all of the tissue compartments. Our MARTIN model was developed and validated using three separate approaches, through an iterative process, as follows. First, the calculated volumes, weights, and dimensions of selected structures were adjusted and confirmed to be within 6% of the literature values for the 2-3-year-old age-range. Second, all structural segmentations were adjusted and confirmed by two experienced, sub-specialty certified neuro-radiologists, also through an interactive process. Third, an additional validation was performed with a Bloch simulator to create synthetic MR image from our MARTIN model and compare the image contrast of the resulting synthetic image with that of the original MRI data; this resulted in a "structural resemblance" index of 0.97. Finally, we used our model to perform pilot MRI safety simulations of an Active Implantable Medical Device (AIMD) using a commercially available software platform (Sim4Life), incorporating the latest International Standards Organization guidelines. This model will be made available on the Athinoula A. Martinos Center for Biomedical Imaging website.
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Affiliation(s)
- Hongbae Jeong
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Georgios Ntolkeras
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michel Alhilani
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Medicine, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Seyed Reza Atefi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Lilla Zöllei
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Kyoko Fujimoto
- Center for Devices and Radiological Health, U. S. Food and Drug Administration, Silver Spring, MD, United States of America
| | - Ali Pourvaziri
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michael H. Lev
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - P. Ellen Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
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11
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Brooks J, Kumar B, Zuro DM, Raybuck JD, Madabushi SS, Vishwasrao P, Parra LE, Kortylewski M, Armstrong B, Froelich J, Hui SK. Biophysical Characterization of the Leukemic Bone Marrow Vasculature Reveals Benefits of Neoadjuvant Low-Dose Radiation Therapy. Int J Radiat Oncol Biol Phys 2021; 109:60-72. [PMID: 32841681 PMCID: PMC7736317 DOI: 10.1016/j.ijrobp.2020.08.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/04/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE Although vascular alterations in solid tumor malignancies are known to decrease therapeutic delivery, the effects of leukemia-induced bone marrow vasculature (BMV) alterations on therapeutic delivery are not well known. Additionally, functional quantitative measurements of the leukemic BMV during chemotherapy and radiation therapy are limited, largely due to a lack of high-resolution imaging techniques available preclinically. This study develops a murine model using compartmental modeling for quantitative multiphoton microscopy (QMPM) to characterize the malignant BMV before and during treatment. METHODS AND MATERIALS Using QMPM, live time-lapsed images of dextran leakage from the local BMV to the surrounding bone marrow of mice bearing acute lymphoblastic leukemia (ALL) were taken and fit to a 2-compartment model to measure the transfer rate (Ktrans), fractional extracellular extravascular space (νec), and vascular permeability parameters, as well as functional single-vessel characteristics. In response to leukemia-induced BMV alterations, the effects of 2 to 4 Gy low-dose radiation therapy (LDRT) on the BMV, drug delivery, and mouse survival were assessed post-treatment to determine whether neoadjuvant LDRT before chemotherapy improves treatment outcome. RESULTS Mice bearing ALL had significantly altered Ktrans, increased νec, and increased permeability compared with healthy mice. Angiogenesis, decreased single-vessel perfusion, and decreased vessel diameter were observed. BMV alterations resulted in disease-dependent reductions in cellular uptake of Hoechst dye. LDRT to mice bearing ALL dilated BMV, increased single-vessel perfusion, and increased daunorubicin uptake by ALL cells. Consequently, LDRT administered to mice before receiving nilotinib significantly increased survival compared with mice receiving LDRT after nilotinib, demonstrating the importance of LDRT conditioning before therapeutic administration. CONCLUSION The developed QMPM enables single-platform assessments of the pharmacokinetics of fluorescent agents and characterization of the BMV. Initial results suggest BMV alterations after neoadjuvant LDRT may contribute to enhanced drug delivery and increased treatment efficacy for ALL. The developed QMPM enables observations of the BMV for use in ALL treatment optimization.
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Affiliation(s)
- Jamison Brooks
- Department of Radiation Oncology, City of Hope, Duarte, California; Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Bijender Kumar
- Department of Radiation Oncology, City of Hope, Duarte, California; Hematology Malignancies and Stem Cell Transplantation Institute, City of Hope National Medical Center, Duarte, California
| | - Darren M Zuro
- Department of Radiation Oncology, City of Hope, Duarte, California; Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | | | | | | | | | - Marcin Kortylewski
- Department of Immuno-Oncology, City of Hope, Duarte, California; Beckman Research Institute of City of Hope, Duarte, California
| | - Brian Armstrong
- Beckman Research Institute of City of Hope, Duarte, California; Department of Development and Stem Cell Biology, City of Hope, Duarte, California
| | - Jerry Froelich
- Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Susanta K Hui
- Department of Radiation Oncology, City of Hope, Duarte, California; Beckman Research Institute of City of Hope, Duarte, California.
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12
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Boissonnat G, Chesneau H, Barat E, Dautremer T, Garcia-Hernandez JC, Lazaro D. Validation of histogram-based virtual source models for different IGRT kV-imaging systems. Med Phys 2020; 47:4531-4542. [PMID: 32497267 DOI: 10.1002/mp.14311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 05/24/2020] [Accepted: 05/26/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Image-guided radiotherapy (IGRT) improves tumor control but its intensive use may entrain late side effects caused by the additional imaging doses. There is a need to better quantify the additional imaging doses, so they can be integrated in the therapeutic workflow. Currently, no dedicated software enables to compute patient-specific imaging doses on a wide range of systems and protocols. As a first step toward this objective, we propose a common methodology to model four different kV-imaging systems used in radiotherapy (Varian's OBI, Elekta's XVI, Brainlab's ExacTrac, and Accuray's Cyberknife) using a new type of virtual source model based on Monte Carlo calculations. METHODS We first describe our method to build a simplified description of the photon output, or virtual source models (VSMs), of each imaging system. Instead of being constructed using measurement data, as it is most commonly the case, our VSM is used as the summary of the phase-space files (PSFs) resulting from a first Monte Carlo simulation of the considered x-ray tube. Second, the VSM is used as a photon generator for a second MC simulation in which we compute the dose. Then, the proposed VSM is thoroughly validated against standard MC simulation using PSFs on the XVI system. Last, each modeled system is compared to profiles and depth-dose-curve measurements performed in homogeneous phantom. RESULTS Comparisons between PSF-based and VSM-based calculations highlight that VSMs could provide equivalent dose results (within 1% of difference) than PSFs inside the imaging field-of-view (FOV). In contrast, VSMs tend to underestimate (for up to 20%) calculated doses outside of the imaging FOV due to the assumptions underlying the VSM construction. In addition, we showed that the use of VSMs allows reducing calculation time by at least a factor of 2.8. Indeed, for identical simulation times, statistical uncertainties on dose distributions computed using VSMs were much lower than those obtained from PSF-based calculations. CONCLUSIONS For each of the four imaging systems, VSMs were successfully validated against measurements in homogeneous phantoms, and are therefore ready to be used for future preclinical studies in heterogeneous or anthropomorphic phantoms. The cross system modeling methodology developed here should enable, later on, to estimate precisely and accurately patient-specific 3D dose maps delivered during a large range of kV-imaging procedures.
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Affiliation(s)
- G Boissonnat
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - H Chesneau
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - E Barat
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - T Dautremer
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | | | - D Lazaro
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
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13
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Kamezawa H, Arimura H, Arakawa H, Kameda N. INVESTIGATION OF A PRACTICAL PATIENT DOSE INDEX FOR ASSESSMENT OF PATIENT ORGAN DOSE FROM CONE-BEAM COMPUTED TOMOGRAPHY IN RADIATION THERAPY USING A MONTE CARLO SIMULATION. RADIATION PROTECTION DOSIMETRY 2018; 181:333-342. [PMID: 29506291 DOI: 10.1093/rpd/ncy032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 02/02/2018] [Indexed: 06/08/2023]
Abstract
The purpose of this study was to investigate a practical patient dose index for assessing the patient organ dose from a cone-beam computed tomography (CBCT) scan by comparing eight dose indices, i.e. CTDI100, CTDIIEC, CTDI∞, midpoint doses f(0)PMMA for a cylindrical polymethyl methacrylate (PMMA) phantom, f(0)Ap for an anthropomorphic phantom and f(0)Pat for a prostate cancer patient, as well as the conventional size specific dose estimations (SSDEconv) and modified SSDE (SSDEmod), with organ dose for the prostate (ODprost) obtained via Monte Carlo (MC) simulation. The ODprost was the reference dose used to find the practical dose index at the center of the pelvic region of a prostate cancer patient. The smallest error rate with respect to the ODprost of 19.3 mGy (reference) among eight dose indices was 5% for f(0)Pat. The practical patient dose index was the f(0)Pat, which showed the smallest error with respect to the reference dose.
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Affiliation(s)
- H Kamezawa
- Department of Radiological Technology, Faculty of Fukuoka Medical Technology, Teikyo University, 6-22 Misaki-machi, Omuta, Fukuoka, Japan
| | - H Arimura
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, Japan
| | - H Arakawa
- Department of Radiological Technology, Faculty of Fukuoka Medical Technology, Teikyo University, 6-22 Misaki-machi, Omuta, Fukuoka, Japan
| | - N Kameda
- Department of Radiology, Fujimoto General Hospital, 17-1, Hayasuzu-cho, Miyakonojo, Miyazaki, Japan
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Lawless MJ, Dimaso L, Palmer B, Micka J, Culberson WS, DeWerd LA. Monte Carlo and60Co‐based kilovoltage x‐ray dosimetry methods. Med Phys 2018; 45:5564-5576. [DOI: 10.1002/mp.13213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 09/07/2018] [Accepted: 09/07/2018] [Indexed: 11/08/2022] Open
Affiliation(s)
- Michael J. Lawless
- Department of Human Oncology University of Wisconsin‐Madison Madison WI 53705USA
| | - Lianna Dimaso
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Benjamin Palmer
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - John Micka
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Wesley S. Culberson
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Larry A. DeWerd
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
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15
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Ding GX, Alaei P, Curran B, Flynn R, Gossman M, Mackie TR, Miften M, Morin R, Xu XG, Zhu TC. Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180. Med Phys 2018; 45:e84-e99. [PMID: 29468678 DOI: 10.1002/mp.12824] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. AIMS This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. MATERIALS & METHODS We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. RESULTS We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. DISCUSSION Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. CONCLUSION Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.
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Affiliation(s)
- George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Parham Alaei
- University of Minnesota, Minneapolis, MN, 55455, USA
| | - Bruce Curran
- Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ryan Flynn
- University of Iowa, Iowa City, IA, 52242, USA
| | | | | | | | | | - X George Xu
- Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Timothy C Zhu
- University of Pennsylvania, Philadelphia, PA, 19104, USA
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16
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Kry SF, Bednarz B, Howell RM, Dauer L, Followill D, Klein E, Paganetti H, Wang B, Wuu CS, George Xu X. AAPM TG 158: Measurement and calculation of doses outside the treated volume from external-beam radiation therapy. Med Phys 2017; 44:e391-e429. [DOI: 10.1002/mp.12462] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Stephen F. Kry
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Bryan Bednarz
- Department of Medical Physics; University of Wisconsin; Madison WI 53705 USA
| | - Rebecca M. Howell
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Larry Dauer
- Departments of Medical Physics/Radiology; Memorial Sloan-Kettering Cancer Center; New York NY 10065 USA
| | - David Followill
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Eric Klein
- Department of Radiation Oncology; Washington University; Saint Louis MO 63110 USA
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital and Harvard Medical School; Boston MA 02114 USA
| | - Brian Wang
- Department of Radiation Oncology; University of Louisville; Louisville KY 40202 USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology; Columbia University; New York NY 10032 USA
| | - X. George Xu
- Department of Mechanical, Aerospace, and Nuclear Engineering; Rensselaer Polytechnic Institute; Troy NY 12180 USA
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Alnewaini Z, Langer E, Schaber P, David M, Kretz D, Steil V, Hesser J. Real-time, ray casting-based scatter dose estimation for c-arm x-ray system. J Appl Clin Med Phys 2017; 18:144-153. [PMID: 28300387 PMCID: PMC5689942 DOI: 10.1002/acm2.12036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 09/08/2016] [Indexed: 11/09/2022] Open
Abstract
Objectives Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. Method The x‐ray source of a Siemens Axiom Artix C‐arm is modeled by a virtual source model using single Gaussian‐shaped source. A Geant4‐based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor. A phase space around these scatterers stores all photon information. Only those photons are traced that hit a surface of phantom that represents medical staff in the treatment room, no indirect scattering is considered; and a complete dose deposition on the surface is calculated. To evaluate the accuracy of the approximation, both experimental measurements using Thermoluminescent dosimeters (TLDs) and a Geant4‐based Monte Carlo simulation of dose depositing for different tube angulations of the C‐arm from cranial‐caudal angle 0° and from LAO (Left Anterior Oblique) 0°–90° are realized. Since the measurements were performed on both sides of the table, using the symmetry of the setup, RAO (Right Anterior Oblique) measurements were not necessary. Results The Geant4‐Monte Carlo simulation agreed within 3% with the measured data, which is within the accuracy of measurement and simulation. The ray casting approximation has been compared to TLD measurements and the achieved percentage difference was −7% for data from tube angulations 45°–90° and −29% from tube angulations 0°–45° on the side of the x‐ray source, whereas on the opposite side of the x‐ray source, the difference was −83.8% and −75%, respectively. Ray casting approximation for only LAO 90° was compared to a Monte Carlo simulation, where the percentage differences were between 0.5–3% on the side of the x‐ray source where the highest dose usually detected was mainly from primary scattering (photons), whereas percentage differences between 2.8–20% are found on the side opposite to the x‐ray source, where the lowest doses were detected. Dose calculation time of our approach was 0.85 seconds. Conclusion The proposed approach yields a fast scatter dose estimation where we could run the Monte Carlo simulation only once for each x‐ray tube angulation to get the Phase Space Files (PSF) for being used later by our ray casting approach to calculate the dose from only photons which will hit an movable elliptical cylinder shaped phantom and getting an output file for the positions of those hits to be used for visualizing the scatter dose propagation on the phantom surface. With dose calculation times of less than one second, we are saving much time compared to using a Monte Carlo simulation instead. With our approach, larger deviations occur only in regions with very low doses, whereas it provides a high precision in high‐dose regions.
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Affiliation(s)
- Zaid Alnewaini
- Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Eric Langer
- Institute and Outpatient Clinic for Diagnostic Radiology, University Hospital Dresden, Dresden, Germany
| | - Philipp Schaber
- Department of Computer Science IV, University of Mannheim, Mannheim, Germany
| | - Matthias David
- Computer Assisted Clinical Medicine, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Dominik Kretz
- Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Volker Steil
- Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
| | - Jürgen Hesser
- Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany
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Marchant TE, Joshi KD. Comprehensive Monte Carlo study of patient doses from cone-beam CT imaging in radiotherapy. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2017; 37:13-30. [PMID: 27922831 DOI: 10.1088/1361-6498/37/1/13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Accurate knowledge of ionizing radiation dose from cone-beam CT (CBCT) imaging in radiotherapy is important to allow concomitant risks to be estimated and for justification of imaging exposures. This study uses a Monte Carlo CBCT model to calculate imaging dose for a wide range of imaging protocols for male and female patients. The Elekta XVI CBCT system was modeled using GATE and simulated doses were validated against measurements in a water tank and thorax phantom. Imaging dose was simulated in the male and female ICRP voxel phantoms for a variety of anatomical sites and imager settings (different collimators, filters, full and partial rotation). The resulting dose distributions were used to calculate effective doses for each scan protocol. The Monte Carlo simulated doses agree with validation measurements within 5% and 10% for water tank and thorax phantom respectively. Effective dose for head CBCT scans was generally lower for scans centred on the pituitary than the larynx (0.03 mSv versus 0.06 mSv for male ICRP phantom). Pelvis CBCT scan effective dose was higher for the female than male phantom (5.11 mSv versus 2.80 mSv for M15 collimator scan), principally due to the higher dose received by gonads for the female scan. Medium field of view thorax scan effective doses ranged from 1.38-3.19 mSv depending on scan length and phantom sex. Effective dose for half rotation thorax scans with offset isocentre varied by almost a factor of three depending on laterality of the isocentre, patient sex and imaged field length. The CBCT imaging doses simulated here reveal large variations in dose depending on imaging isocentre location, patient sex and partial rotation angles. This information may be used to estimate risks from CBCT and to optimize CBCT imaging protocols.
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Affiliation(s)
- T E Marchant
- The University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, M20 4BX, UK. Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, M20 4BX, UK
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19
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Vilches-Freixas G, Létang JM, Brousmiche S, Romero E, Vila Oliva M, Kellner D, Deutschmann H, Keuschnigg P, Steininger P, Rit S. Technical Note: Procedure for the calibration and validation of kilo-voltage cone-beam CT models. Med Phys 2016; 43:5199. [DOI: 10.1118/1.4961400] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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20
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Choi JH, Constantin D, Ganguly A, Girard E, Morin RL, Dixon RL, Fahrig R. Practical dose point-based methods to characterize dose distribution in a stationary elliptical body phantom for a cone-beam C-arm CT system. Med Phys 2016; 42:4920-32. [PMID: 26233218 DOI: 10.1118/1.4927257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To propose new dose point measurement-based metrics to characterize the dose distributions and the mean dose from a single partial rotation of an automatic exposure control-enabled, C-arm-based, wide cone angle computed tomography system over a stationary, large, body-shaped phantom. METHODS A small 0.6 cm(3) ion chamber (IC) was used to measure the radiation dose in an elliptical body-shaped phantom made of tissue-equivalent material. The IC was placed at 23 well-distributed holes in the central and peripheral regions of the phantom and dose was recorded for six acquisition protocols with different combinations of minimum kVp (109 and 125 kVp) and z-collimator aperture (full: 22.2 cm; medium: 14.0 cm; small: 8.4 cm). Monte Carlo (MC) simulations were carried out to generate complete 2D dose distributions in the central plane (z = 0). The MC model was validated at the 23 dose points against IC experimental data. The planar dose distributions were then estimated using subsets of the point dose measurements using two proposed methods: (1) the proximity-based weighting method (method 1) and (2) the dose point surface fitting method (method 2). Twenty-eight different dose point distributions with six different point number cases (4, 5, 6, 7, 14, and 23 dose points) were evaluated to determine the optimal number of dose points and their placement in the phantom. The performances of the methods were determined by comparing their results with those of the validated MC simulations. The performances of the methods in the presence of measurement uncertainties were evaluated. RESULTS The 5-, 6-, and 7-point cases had differences below 2%, ranging from 1.0% to 1.7% for both methods, which is a performance comparable to that of the methods with a relatively large number of points, i.e., the 14- and 23-point cases. However, with the 4-point case, the performances of the two methods decreased sharply. Among the 4-, 5-, 6-, and 7-point cases, the 7-point case (1.0% [±0.6%] difference) and the 6-point case (0.7% [±0.6%] difference) performed best for method 1 and method 2, respectively. Moreover, method 2 demonstrated high-fidelity surface reconstruction with as few as 5 points, showing pixelwise absolute differences of 3.80 mGy (±0.32 mGy). Although the performance was shown to be sensitive to the phantom displacement from the isocenter, the performance changed by less than 2% for shifts up to 2 cm in the x- and y-axes in the central phantom plane. CONCLUSIONS With as few as five points, method 1 and method 2 were able to compute the mean dose with reasonable accuracy, demonstrating differences of 1.7% (±1.2%) and 1.3% (±1.0%), respectively. A larger number of points do not necessarily guarantee better performance of the methods; optimal choice of point placement is necessary. The performance of the methods is sensitive to the alignment of the center of the body phantom relative to the isocenter. In body applications where dose distributions are important, method 2 is a better choice than method 1, as it reconstructs the dose surface with high fidelity, using as few as five points.
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Affiliation(s)
- Jang-Hwan Choi
- Department of Radiology, Stanford University, Stanford, California 94305 and Department of Mechanical Engineering, Stanford University, Stanford, California 94305
| | - Dragos Constantin
- Microwave Physics R&E, Varian Medical Systems, Palo Alto, California 94304
| | - Arundhuti Ganguly
- Department of Radiology, Stanford University, Stanford, California 94305
| | - Erin Girard
- Department of Radiology, Stanford University, Stanford, California 94305
| | | | - Robert L Dixon
- Department of Radiology, Wake Forest University, Winston-Salem, North Carolina 27157
| | - Rebecca Fahrig
- Department of Radiology, Stanford University, Stanford, California 94305
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Menten MJ, Fast MF, Nill S, Oelfke U. Using dual-energy x-ray imaging to enhance automated lung tumor tracking during real-time adaptive radiotherapy. Med Phys 2015; 42:6987-98. [PMID: 26632054 DOI: 10.1118/1.4935431] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 10/20/2015] [Accepted: 10/28/2015] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Real-time, markerless localization of lung tumors with kV imaging is often inhibited by ribs obscuring the tumor and poor soft-tissue contrast. This study investigates the use of dual-energy imaging, which can generate radiographs with reduced bone visibility, to enhance automated lung tumor tracking for real-time adaptive radiotherapy. METHODS kV images of an anthropomorphic breathing chest phantom were experimentally acquired and radiographs of actual lung cancer patients were Monte-Carlo-simulated at three imaging settings: low-energy (70 kVp, 1.5 mAs), high-energy (140 kVp, 2.5 mAs, 1 mm additional tin filtration), and clinical (120 kVp, 0.25 mAs). Regular dual-energy images were calculated by weighted logarithmic subtraction of high- and low-energy images and filter-free dual-energy images were generated from clinical and low-energy radiographs. The weighting factor to calculate the dual-energy images was determined by means of a novel objective score. The usefulness of dual-energy imaging for real-time tracking with an automated template matching algorithm was investigated. RESULTS Regular dual-energy imaging was able to increase tracking accuracy in left-right images of the anthropomorphic phantom as well as in 7 out of 24 investigated patient cases. Tracking accuracy remained comparable in three cases and decreased in five cases. Filter-free dual-energy imaging was only able to increase accuracy in 2 out of 24 cases. In four cases no change in accuracy was observed and tracking accuracy worsened in nine cases. In 9 out of 24 cases, it was not possible to define a tracking template due to poor soft-tissue contrast regardless of input images. The mean localization errors using clinical, regular dual-energy, and filter-free dual-energy radiographs were 3.85, 3.32, and 5.24 mm, respectively. Tracking success was dependent on tumor position, tumor size, imaging beam angle, and patient size. CONCLUSIONS This study has highlighted the influence of patient anatomy on the success rate of real-time markerless tumor tracking using dual-energy imaging. Additionally, the importance of the spectral separation of the imaging beams used to generate the dual-energy images has been shown.
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Affiliation(s)
- Martin J Menten
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, United Kingdom
| | - Martin F Fast
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, United Kingdom
| | - Simeon Nill
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, United Kingdom
| | - Uwe Oelfke
- Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, United Kingdom
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Partial kilovoltage cone beam computed tomography, complete kilovoltage cone beam computed tomography, and electronic portal images for breast radiation therapy: A dose-comparison study. Pract Radiat Oncol 2015; 5:e521-e529. [DOI: 10.1016/j.prro.2015.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 01/28/2015] [Accepted: 02/15/2015] [Indexed: 12/30/2022]
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Hioki K, Araki F, Ohno T, Tomiyama Y, Nakaguchi Y. Monte Carlo-calculated patient organ doses from kV-cone beam CT in image-guided radiation therapy. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/2/025203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Alaei P, Spezi E. Imaging dose from cone beam computed tomography in radiation therapy. Phys Med 2015; 31:647-58. [PMID: 26148865 DOI: 10.1016/j.ejmp.2015.06.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/29/2015] [Accepted: 06/05/2015] [Indexed: 12/26/2022] Open
Abstract
Imaging dose in radiation therapy has traditionally been ignored due to its low magnitude and frequency in comparison to therapeutic dose used to treat patients. The advent of modern, volumetric, imaging modalities, often as an integral part of linear accelerators, has facilitated the implementation of image-guided radiation therapy (IGRT), which is often accomplished by daily imaging of patients. Daily imaging results in additional dose delivered to patient that warrants new attention be given to imaging dose. This review summarizes the imaging dose delivered to patients as the result of cone beam computed tomography (CBCT) imaging performed in radiation therapy using current methods and equipment. This review also summarizes methods to calculate the imaging dose, including the use of Monte Carlo (MC) and treatment planning systems (TPS). Peripheral dose from CBCT imaging, dose reduction methods, the use of effective dose in describing imaging dose, and the measurement of CT dose index (CTDI) in CBCT systems are also reviewed.
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Affiliation(s)
| | - Emiliano Spezi
- School of Engineering, Cardiff University, Cardiff, Wales, UK; Velindre Cancer Centre, Cardiff, Wales, UK
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Azimi R, Alaei P, Spezi E, Hui SK. Characterization of an orthovoltage biological irradiator used for radiobiological research. JOURNAL OF RADIATION RESEARCH 2015; 56:485-492. [PMID: 25694476 PMCID: PMC4426923 DOI: 10.1093/jrr/rru129] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/16/2014] [Accepted: 12/27/2014] [Indexed: 06/01/2023]
Abstract
Orthovoltage irradiators are routinely used to irradiate specimens and small animals in biological research. There are several reports on the characteristics of these units for small field irradiations. However, there is limited knowledge about use of these units for large fields, which are essential for emerging large-field irregular shape irradiations, namely total marrow irradiation used as a conditioning regimen for hematological malignancies. This work describes characterization of a self-contained Orthovoltage biological irradiator for large fields using measurements and Monte Carlo simulations that could be used to compute the dose for in vivo or in vitro studies for large-field irradiation using this or a similar unit. Percentage depth dose, profiles, scatter factors, and half-value layers were measured and analyzed. A Monte Carlo model of the unit was created and used to generate depth dose and profiles, as well as scatter factors. An ion chamber array was also used for profile measurements of flatness and symmetry. The output was determined according to AAPM Task Group 61 guidelines. The depth dose measurements compare well with published data for similar beams. The Monte Carlo-generated depth dose and profiles match our measured doses to within 2%. Scatter factor measurements indicate gradual variation of these factors with field size. Dose rate measured by placing the ion chamber atop the unit's steel plate or solid water indicate enhanced readings of 5 to 28% compared with those measured in air. The stability of output over a 5-year period is within 2% of the 5-year average.
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Affiliation(s)
- Rezvan Azimi
- Department of Radiation Oncology, University of Minnesota, 420 Delaware Street, SE MMC 494, Minneapolis, MN 55455, USA
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, 420 Delaware Street, SE MMC 494, Minneapolis, MN 55455, USA
| | - Emiliano Spezi
- Department of Medical Physics, Velindre Cancer Centre, Velindre Road, CF14 2TL, Cardiff, UK
| | - Susanta K Hui
- Department of Radiation Oncology, University of Minnesota, 420 Delaware Street, SE MMC 494, Minneapolis, MN 55455, USA
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Thing RS, Mainegra-Hing E. Optimizing cone beam CT scatter estimation in egs_cbct for a clinical and virtual chest phantom. Med Phys 2015; 41:071902. [PMID: 24989380 DOI: 10.1118/1.4881142] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Cone beam computed tomography (CBCT) image quality suffers from contamination from scattered photons in the projection images. Monte Carlo simulations are a powerful tool to investigate the properties of scattered photons.egs_cbct, a recent EGSnrc user code, provides the ability of performing fast scatter calculations in CBCT projection images. This paper investigates how optimization of user inputs can provide the most efficient scatter calculations. METHODS Two simulation geometries with two different x-ray sources were simulated, while the user input parameters for the efficiency improving techniques (EITs) implemented inegs_cbct were varied. Simulation efficiencies were compared to analog simulations performed without using any EITs. Resulting scatter distributions were confirmed unbiased against the analog simulations. RESULTS The optimal EIT parameter selection depends on the simulation geometry and x-ray source. Forced detection improved the scatter calculation efficiency by 80%. Delta transport improved calculation efficiency by a further 34%, while particle splitting combined with Russian roulette improved the efficiency by a factor of 45 or more. Combining these variance reduction techniques with a built-in denoising algorithm, efficiency improvements of 4 orders of magnitude were achieved. CONCLUSIONS Using the built-in EITs inegs_cbct can improve scatter calculation efficiencies by more than 4 orders of magnitude. To achieve this, the user must optimize the input parameters to the specific simulation geometry. Realizing the full potential of the denoising algorithm requires keeping the statistical uncertainty below a threshold value above which the efficiency drops exponentially.
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Affiliation(s)
- Rune Slot Thing
- Institute of Clinical Research, University of Southern Denmark, Odense 5000, Denmark and Laboratory of Radiation Physics, Odense University Hospital, Odense 5000, Denmark
| | - Ernesto Mainegra-Hing
- Ionizing Radiation Standards, National Research Council of Canada, Ottawa K1A 0R6, Canada
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Abuhaimed A, Martin CJ, Sankaralingam M, Gentle DJ. A Monte Carlo investigation of cumulative dose measurements for cone beam computed tomography (CBCT) dosimetry. Phys Med Biol 2015; 60:1519-42. [PMID: 25615012 DOI: 10.1088/0031-9155/60/4/1519] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Many studies have shown that the computed tomography dose index (CTDI100) which is considered as a main dose descriptor for CT dosimetry fails to provide a realistic reflection of the dose involved in cone beam computed tomography (CBCT) scans. Several practical approaches have been proposed to overcome drawbacks of the CTDI100. One of these is the cumulative dose concept. The purpose of this study was to investigate four different approaches based on the cumulative dose concept: the cumulative dose (1) f(0,150) and (2) f(0,∞) with a small ionization chamber 20 mm long, and the cumulative dose (3) f100(150) and (4) f100(∞) with a standard 100 mm pencil ionization chamber. The study also aimed to investigate the influence of using the 20 and 100 mm chambers and the standard and the infinitely long phantoms on cumulative dose measurements. Monte Carlo EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc codes were used to simulate a kV imaging system integrated with a TrueBeam linear accelerator and to calculate doses within cylindrical head and body PMMA phantoms with diameters of 16 cm and 32 cm, respectively, and lengths of 150, 600, 900 mm. f(0,150) and f100(150) approaches were studied within the standard PMMA phantoms (150 mm), while the other approaches f(0,∞) and f100(∞) were within infinitely long head (600 mm) and body (900 mm) phantoms. CTDI∞ values were used as a standard to compare the dose values for the approaches studied at the centre and periphery of the phantoms and for the weighted values. Four scanning protocols and beams of width 20-300 mm were used. It has been shown that the f(0,∞) approach gave the highest dose values which were comparable to CTDI∞ values for wide beams. The differences between the weighted dose values obtained with the 20 and 100 mm chambers were significant for the beam widths <120 mm, but these differences declined with increasing beam widths to be within 4%. The weighted dose values calculated within the infinitely long phantoms with both the chambers for the beam widths ≤140 were within 3% of those within the standard phantoms, but the differences rose to be within 15% at wider beams. By comparing the approaches studied in this investigation with other methodologies taking into account the efficiency of the approach as a dose descriptor and the simplicity of the implementation in the clinical environment, the f(0,150) method may be the best for CBCT dosimetry combined with the use of correction factors.
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Affiliation(s)
- Abdullah Abuhaimed
- Radiotherapy Physics, Department of Clinical Physics and Bioengineering, Beatson West of Scotland Cancer Centre, Glasgow, UK. Department of Clinical Physics, University of Glasgow, Glasgow, UK. Department of Applied Physics, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
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Brochu FM, Burnet NG, Jena R, Plaistow R, Parker MA, Thomas SJ. Geant4 simulation of the Elekta XVI kV CBCT unit for accurate description of potential late toxicity effects of image-guided radiotherapy. Phys Med Biol 2014; 59:7601-8. [PMID: 25415354 DOI: 10.1088/0031-9155/59/24/7601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This paper describes the modelisation of the Elekta XVI Cone Beam Computed Tomography (CBCT) machine components with Geant4 and its validation against calibration data taken for two commonly used machine setups. Preliminary dose maps of simulated CBCTs coming from this modelisation work are presented. This study is the first step of a research project, GHOST, aiming to improve the understanding of late toxicity risk in external beam radiotherapy patients by simulating dose depositions integrated from different sources (imaging, treatment beam) over the entire treatment plan. The second cancer risk will then be derived from different models relating irradiation dose and second cancer risk.
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Affiliation(s)
- F M Brochu
- University of Cambridge, Department of Oncology, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK. University of Cambridge, Department of Physics, Cavendish Laboratory, J J Thomson Avenue, Cambridge, UK
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Hioki K, Araki F, Ohno T, Nakaguchi Y, Tomiyama Y. Absorbed dose measurements for kV-cone beam computed tomography in image-guided radiation therapy. Phys Med Biol 2014; 59:7297-313. [DOI: 10.1088/0031-9155/59/23/7297] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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30
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Abuhaimed A, J Martin C, Sankaralingam M, J Gentle D, McJury M. An assessment of the efficiency of methods for measurement of the computed tomography dose index (CTDI) for cone beam (CBCT) dosimetry by Monte Carlo simulation. Phys Med Biol 2014; 59:6307-26. [DOI: 10.1088/0031-9155/59/21/6307] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Nelson AP, Ding GX. An alternative approach to account for patient organ doses from imaging guidance procedures. Radiother Oncol 2014; 112:112-8. [DOI: 10.1016/j.radonc.2014.05.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 05/05/2014] [Accepted: 05/24/2014] [Indexed: 11/16/2022]
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Alaei P, Spezi E, Reynolds M. Dose calculation and treatment plan optimization including imaging dose from kilovoltage cone beam computed tomography. Acta Oncol 2014; 53:839-44. [PMID: 24438661 DOI: 10.3109/0284186x.2013.875626] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND With the increasing use of cone beam computed tomography (CBCT) for patient position verification and radiotherapy treatment adaptation, there is an increasing need to develop techniques that can take into account concomitant dose using a personalized approach. MATERIAL AND METHODS A total of 20 patients (10 pelvis and 10 head and neck) who had undergone radiation therapy using intensity modulated radiation therapy (IMRT) were selected and the dose from kV CBCT was retrospectively calculated using a treatment planning system previously commissioned for this purpose. The imaging dose was added to the CT images used for treatment planning and the difference in its addition prior to and after the planning was assessed. RESULTS The additional isocenter dose as a result of daily CBCT is in the order of 3-4 cGy for 35-fraction head and neck and 23-47 cGy for 25-fraction pelvis cases using the standard head and neck and pelvis image acquisition protocols. The pelvic dose is especially dependent on patient size and body mass index (BMI), being higher for patients with lower BMI. Due to the low energy of the kV CBCT beam, the maximum energy deposition is at or near the surface with the highest dose being on the patient's left side for the head and neck (∼7 cGy) and on the posterior for the pelvic cases (∼80 cGy). Addition of imaging dose prior to plan optimization resulted in an average reduction of 4% in the plan monitor units and 5% in the number of control points. CONCLUSION Dose from daily kV CBCT has been added to patient treatment plans using previously commissioned kV CBCT beams in a treatment planning system. Addition of imaging dose can be included in IMRT treatment plan optimization and would facilitate customization of imaging protocol based on patient anatomy and location of isocenter.
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Affiliation(s)
- Parham Alaei
- Department of Radiation Oncology, University of Minnesota , Minneapolis, Minnesota , USA
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33
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Pawlowski JM, Ding GX. An algorithm for kilovoltage x-ray dose calculations with applications in kV-CBCT scans and 2D planar projected radiographs. Phys Med Biol 2014; 59:2041-58. [DOI: 10.1088/0031-9155/59/8/2041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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34
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Imaging dose assessment for IGRT in particle beam therapy. Radiother Oncol 2013; 109:409-13. [DOI: 10.1016/j.radonc.2013.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 09/01/2013] [Accepted: 09/08/2013] [Indexed: 12/25/2022]
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Ding GX, Malcolm AW. An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures. Phys Med Biol 2013; 58:5885-97. [DOI: 10.1088/0031-9155/58/17/5885] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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36
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Ding GX, Munro P. Radiation exposure to patients from image guidance procedures and techniques to reduce the imaging dose. Radiother Oncol 2013; 108:91-8. [PMID: 23830468 DOI: 10.1016/j.radonc.2013.05.034] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 04/08/2013] [Accepted: 05/09/2013] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare imaging doses from MV images, kV radiographs, and kV-CBCT and describe methods to reduce the dose to patient's organs using existing on-board imaging devices. METHOD AND MATERIALS Monte Carlo techniques were used to simulate kV X-ray sources. The kV image doses to a variety of patient anatomies were calculated by using the simulated realistic sources to deposit dose in patient CT images. For MV imaging, the doses for the same patients were calculated using a commercial treatment planning system. RESULTS Portal imaging results in the largest dose to anatomic structures, followed by Varian OBI CBCT, Varian TrueBeam CBCT and then kV radiographs. The imaging doses for the 50% volume from the DVHs, D50, to the eyes for representative head images are 4.3-4.8cGy; 0.05-0.06cGy; 0.04-0.05cGy; and, 0.12cGy; D50 to the bladder for representative pelvis images are 3.3cGy; 1.6cGy; 1.0cGy; and, 0.07cGy; while D50 to the heart for representative thorax images are 3.5cGy; 0.42cGy; 0.2cGy; and, 0.07cGy; when using portal imaging, OBI kV-CBCT scans, TrueBeam kV-CBCT scans and kV radiographs, respectively. The orientation of the kV beam can affect organ dose. For example, D50 to the eyes can be reduced from 0.12cGy using AP and right lateral radiographs to 0.008-0.017cGy when using PA and right lateral radiographs. In addition, organ exposures can be further reduced to 15-70% of their original values with the use of a full-fan, bow-tie filter for kV radiographs. In contrast, organ doses increase by a factor of ∼2-4 if bow-tie filters are not used during kV-CBCT acquisitions. CONCLUSION Current on-board kV imaging devices result in much lower imaging doses compared to MV imagers even taking into account of higher bone dose from kV X-rays. And a variety of approaches are available to significantly reduce the image doses.
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Affiliation(s)
- George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville 37232-5671, USA.
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Sykes JR, Lindsay R, Iball G, Thwaites DI. Dosimetry of CBCT: methods, doses and clinical consequences. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/444/1/012017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Halg RA, Besserer J, Schneider U. Systematic measurements of whole-body imaging dose distributions in image-guided radiation therapy. Med Phys 2013; 39:7650-61. [PMID: 23231313 DOI: 10.1118/1.4758065] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The full benefit of the increased precision of contemporary treatment techniques can only be exploited if the accuracy of the patient positioning is guaranteed. Therefore, more and more imaging modalities are used in the process of the patient setup in clinical routine of radiation therapy. The improved accuracy in patient positioning, however, results in additional dose contributions to the integral patient dose. To quantify this, absorbed dose measurements from typical imaging procedures involved in an image-guided radiation therapy treatment were measured in an anthropomorphic phantom for a complete course of treatment. The experimental setup, including the measurement positions in the phantom, was exactly the same as in a preceding study of radiotherapy stray dose measurements. This allows a direct combination of imaging dose distributions with the therapy dose distribution. METHODS Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from imaging devices used with treatment machines from the manufacturers Accuray, Elekta, Siemens, and Varian and from computed tomography scanners from GE Healthcare were determined and the resulting effective dose was calculated. The list of investigated imaging techniques consisted of cone beam computed tomography (kilo- and megavoltage), megavoltage fan beam computed tomography, kilo- and megavoltage planar imaging, planning computed tomography with and without gating methods and planar scout views. RESULTS A conventional 3D planning CT resulted in an effective dose additional to the treatment stray dose of less than 1 mSv outside of the treated volume, whereas a 4D planning CT resulted in a 10 times larger dose. For a daily setup of the patient with two planar kilovoltage images or with a fan beam CT at the TomoTherapy unit, an additional effective dose outside of the treated volume of less than 0.4 mSv and 1.4 mSv was measured, respectively. Using kilovoltage or megavoltage radiation to obtain cone beam computed tomography scans led to an additional dose of 8-46 mSv. For treatment verification images performed once per week using double exposure technique, an additional effective dose of up to 18 mSv was measured. CONCLUSIONS Daily setup imaging using kilovoltage planar images or TomoTherapy megavoltage fan beam CT imaging can be used as a standard procedure in clinical routine. Daily kilovoltage and megavoltage cone beam computed tomography setup imaging should be applied on an individual or indication based protocol. Depending on the imaging scheme applied, image-guided radiation therapy can be administered without increasing the dose outside of the treated volume compared to therapies without image guidance.
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Affiliation(s)
- Roger A Halg
- Radiotherapie Hirslanden AG, Institute for Radiotherapy, Aarau, Switzerland.
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Alaei P, Spezi E. Commissioning kilovoltage cone-beam CT beams in a radiation therapy treatment planning system. J Appl Clin Med Phys 2012; 13:3971. [PMID: 23149789 PMCID: PMC5718524 DOI: 10.1120/jacmp.v13i6.3971] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/15/2012] [Accepted: 06/18/2012] [Indexed: 11/23/2022] Open
Abstract
The feasibility of accounting of the dose from kilovoltage cone‐beam CT in treatment planning has been discussed previously for a single cone‐beam CT (CBCT) beam from one manufacturer. Modeling the beams and computing the dose from the full set of beams produced by a kilovoltage cone‐beam CT system requires extensive beam data collection and verification, and is the purpose of this work. The beams generated by Elekta X‐ray volume imaging (XVI) kilovoltage CBCT (kV CBCT) system for various cassettes and filters have been modeled in the Philips Pinnacle treatment planning system (TPS) and used to compute dose to stack and anthropomorphic phantoms. The results were then compared to measurements made using thermoluminescent dosimeters (TLDs) and Monte Carlo (MC) simulations. The agreement between modeled and measured depth‐dose and cross profiles is within 2% at depths beyond 1 cm for depth‐dose curves, and for regions within the beam (excluding penumbra) for cross profiles. The agreements between TPS‐calculated doses, TLD measurements, and Monte Carlo simulations are generally within 5% in the stack phantom and 10% in the anthropomorphic phantom, with larger variations observed for some of the measurement/calculation points. Dose computation using modeled beams is reasonably accurate, except for regions that include bony anatomy. Inclusion of this dose in treatment plans can lead to more accurate dose prediction, especially when the doses to organs at risk are of importance. PACS numbers: 87.55.D, 87.55.K, 87.56.bd
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Affiliation(s)
- Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, MN 55455, USA.
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40
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Contribution to normal tissue dose from concomitant radiation for two common kV-CBCT systems and one MVCT system used in radiotherapy. Radiother Oncol 2012; 105:139-44. [DOI: 10.1016/j.radonc.2012.04.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 03/29/2012] [Accepted: 04/03/2012] [Indexed: 11/19/2022]
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41
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Stock M, Palm A, Altendorfer A, Steiner E, Georg D. IGRT induced dose burden for a variety of imaging protocols at two different anatomical sites. Radiother Oncol 2012; 102:355-63. [DOI: 10.1016/j.radonc.2011.10.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 09/23/2011] [Accepted: 10/16/2011] [Indexed: 10/15/2022]
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Kida S, Masutani Y, Yamashita H, Imae T, Matsuura T, Saotome N, Ohtomo K, Nakagawa K, Haga A. In-treatment 4D cone-beam CT with image-based respiratory phase recognition. Radiol Phys Technol 2012; 5:138-47. [DOI: 10.1007/s12194-012-0146-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 02/05/2012] [Accepted: 02/13/2012] [Indexed: 11/30/2022]
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Kim S, Song H, Movsas B, Chetty IJ. Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations. Med Phys 2011; 39:320-9. [DOI: 10.1118/1.3670377] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Spezi E, Downes P, Jarvis R, Radu E, Staffurth J. Patient-specific three-dimensional concomitant dose from cone beam computed tomography exposure in image-guided radiotherapy. Int J Radiat Oncol Biol Phys 2011; 83:419-26. [PMID: 22027261 DOI: 10.1016/j.ijrobp.2011.06.1972] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 05/24/2011] [Accepted: 06/10/2011] [Indexed: 12/31/2022]
Abstract
PURPOSE The purpose of the present study was to quantify the concomitant dose received by patients undergoing cone beam computed tomography (CBCT) scanning in different clinical scenarios as a part of image-guided radiotherapy (IGRT) procedures. METHODS AND MATERIALS We calculated the three-dimensional concomitant dose received as a result of CBCT scans in 6 patients representing different clinical scenarios: two pelvis, two head and neck, and two chest. We assessed the effect that a daily on-line IGRT strategy would have on the patient dose distribution, assuming 40 CBCT scans throughout the treatment course. The additional dose to the planning target volume margin region was also estimated. RESULTS In the pelvis, a single CBCT scan delivered a mean dose to the femoral heads of 2-6 cGy and the rectum of 1-2 cGy. An additional dose to the planning target volume was within 1-3 cGy. In the chest, the mean dose to the planning target volume varied from 2.5 to 5 cGy. The lung and spinal cord planning organ at risk volume received ≤4 cGy and ≤5 cGy, respectively. In the head and neck, a single CBCT scan delivered a mean dose of 0.3 cGy, with bony structures receiving 0.5-0.8 cGy. The femoral heads received an additional dose of 1.5-2.5 Gy. A reduction of 20-30% in the mean dose to the organs at risk was achieved using bowtie filtration. In the head and neck, the dose to the eyes and brainstem was eliminated by decreasing the craniocaudal field size. CONCLUSIONS The additional dose from on-line IGRT procedures can be clinically relevant. The organ dose can be significantly reduced with the use of appropriate patient-specific settings. The concomitant dose from CBCT should be accounted for and the acquisition settings optimized for optimal IGRT strategies on a patient basis.
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Affiliation(s)
- Emiliano Spezi
- Department of Medical Physics, Velindre Cancer Centre, Cardiff, United Kingdom.
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Spezi E, Volken W, Frei D, Fix MK. A virtual source model for Kilo-voltage cone beam CT: Source characteristics and model validation. Med Phys 2011; 38:5254-63. [DOI: 10.1118/1.3626574] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Zhang G, Pauwels R, Marshall N, Shaheen E, Nuyts J, Jacobs R, Bosmans H. Development and validation of a hybrid simulation technique for cone beam CT: application to an oral imaging system. Phys Med Biol 2011; 56:5823-43. [PMID: 21846936 DOI: 10.1088/0031-9155/56/18/004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This paper proposes a hybrid technique to simulate the complete chain of an oral cone beam computed tomography (CBCT) system for the study of both radiation dose and image quality. The model was developed around a 3D Accuitomo 170 unit (J Morita, Japan) with a tube potential range of 60-90 kV. The Monte Carlo technique was adopted to simulate the x-ray generation, filtration and collimation. Exact dimensions of the bow-tie filter were estimated iteratively using experimentally acquired flood images. Non-flat radiation fields for different exposure settings were mediated via 'phase spaces'. Primary projection images were obtained by ray tracing at discrete energies and were fused according to the two-dimensional energy modulation templates derived from the phase space. Coarse Monte Carlo simulations were performed for scatter projections and the resulting noisy images were smoothed by Richardson-Lucy fitting. Resolution and noise characteristics of the flat panel detector were included using the measured modulation transfer function (MTF) and the noise power spectrum (NPS), respectively. The Monte Carlo dose calculation was calibrated in terms of kerma free-in-air about the isocenter, using an ionization chamber, and was subsequently validated by comparison against the measured air kerma in water at various positions of a cylindrical water phantom. The resulting dose discrepancies were found <10% for most cases. Intensity profiles of the experimentally acquired and simulated projection images of the water phantom showed comparable fractional increase over the common area as changing from a small to a large field of view, suggesting that the scatter was accurately accounted. Image validation was conducted using two small phantoms and the built-in quality assurance protocol of the system. The reconstructed simulated images showed high resemblance on contrast resolution, noise appearance and artifact pattern in comparison to experimentally acquired images, with <5% difference for voxel values of the aluminum and air insert regions and <3% difference for voxel uniformity across the homogeneous PMMA region. The detector simulation by use of the MTF and NPS data exhibited a big influence on noise and the sharpness of the resulting images. The hybrid simulation technique is flexible and has wide applicability to CBCT systems.
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Affiliation(s)
- G Zhang
- Department of Radiology, University Hospitals Leuven, Herestraat 49, Leuven 3000, Belgium.
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Park JC, Park SH, Kim JS, Han Y, Cho MK, Kim HK, Liu Z, Jiang SB, Song B, Song WY. Ultra-Fast Digital Tomosynthesis Reconstruction Using General-Purpose GPU Programming for Image-Guided Radiation Therapy. Technol Cancer Res Treat 2011; 10:295-306. [DOI: 10.7785/tcrt.2012.500206] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The purpose of this work is to demonstrate an ultra-fast reconstruction technique for digital tomosynthesis (DTS) imaging based on the algorithm proposed by Feldkamp, Davis, and Kress (FDK) using standard general-purpose graphics processing unit (GPGPU) programming interface. To this end, the FDK-based DTS algorithm was programmed “in-house” with C language with utilization of 1) GPU and 2) central processing unit (CPU) cards. The GPU card consisted of 480 processing cores (2 × 240 dual chip) with 1,242 MHz processing clock speed and 1,792 MB memory space. In terms of CPU hardware, we used 2.68 GHz clock speed, 12.0 GB DDR3 RAM, on a 64-bit OS. The performance of proposed algorithm was tested on twenty-five patient cases (5 lung, 5 liver, 10 prostate, and 5 head-and-neck) scanned either with a full-fan or half-fan mode on our cone-beam computed tomography (CBCT) system. For the full-fan scans, the projections from 157.5°–202.5° (45°-scan) were used to reconstruct coronal DTS slices, whereas for the half-fan scans, the projections from both 157.5°–202.5° and 337.5°–22.5° (2 × 45°-scan) were used to reconstruct larger FOV coronal DTS slices. For this study, we chose 45°-scan angle that contained ~80 projections for the full-fan and ~160 projections with 2 × 45°-scan angle for the half-fan mode, each with 1024 × 768 pixels with 32-bit precision. Absolute pixel value differences, profiles, and contrast-to-noise ratio (CNR) calculations were performed to compare and evaluate the images reconstructed using GPU- and CPU-based implementations. The time dependence on the reconstruction volume was also tested with (512 × 512) × 16, 32, 64, 128, and 256 slices. In the end, the GPU-based implementation achieved, at most, 1.3 and 2.5 seconds to complete full reconstruction of 512 × 512 × 256 volume, for the full-fan and half-fan modes, respectively. In turn, this meant that our implementation can process > 13 projections-per-second (pps) and > 18 pps for the full-fan and half-fan modes, respectively. Since commercial CBCT system nominally acquires 11 pps (with 1 gantry-revolution-per-minute), our GPU-based implementation is sufficient to handle the incoming projections data as they are acquired and reconstruct the entire volume immediately after completing the scan. In addition, on increasing the number of slices (hence volume) to be reconstructed from 16 to 256, only minimal increases in reconstruction time were observed for the GPU-based implementation where from 0.73 to 1.27 seconds and 1.42 to 2.47 seconds increase were observed for the full-fan and half-fan modes, respectively. This resulted in speed improvement of up to 87 times compared with the CPU-based implementation (for 256 slices case), with visually identical images and small pixel-value discrepancies (< 6.3%), and CNR differences (< 2.3%). With this achievement, we have shown that time allocation for DTS image reconstruction is virtually eliminated and that clinical implementation of this approach has become quite appealing. In addition, with the speed achievement, further image processing and real-time applications that was prohibited prior due to time restrictions can now be tempered with.
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Affiliation(s)
- Justin C. Park
- Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California
| | - Sung Ho Park
- Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea
| | - Jin Sung Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Youngyih Han
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Min Kook Cho
- Department of Mechanical Engineering, Pusan National University, Busan, South Korea
| | - Ho Kyung Kim
- Department of Mechanical Engineering, Pusan National University, Busan, South Korea
| | - Zhaowei Liu
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California
| | - Steve B. Jiang
- Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California
| | - Bongyong Song
- Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California
| | - William Y. Song
- Department of Radiation Oncology, Center for Advanced Radiotherapy Technologies, University of California San Diego, La Jolla, California
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Validation of a Monte Carlo simulation for dose assessment in dental cone beam CT examinations. Phys Med 2011; 28:200-9. [PMID: 21807542 DOI: 10.1016/j.ejmp.2011.06.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/02/2011] [Accepted: 06/28/2011] [Indexed: 11/22/2022] Open
Abstract
A Monte Carlo (MC) simulation for calculating absorbed dose has been developed and applied for dental applications with an i-CAT cone beam CT (CBCT) system. To validate the method a comparison was made between calculated and measured dose values for two different clinical protocols. Measurements with a pencil CT chamber were performed free-in-air and in a CT dose head phantom; measurements were also performed with a transmission ionization chamber. In addition for each protocol a total number of 58 thermoluminescence dosemeters (TLD) were packed in groups and placed at 16 representative anatomical locations of an anthropomorphic phantom (Remab system) to assess absorbed doses. To simulate X-ray exposure, a software application based on the EGS4 package was applied. Dose quantities were calculated for different voxelized models representing the CT ionization and transmission chambers, the TLDs, and the phantoms as well. The dose quantities evaluated in the comparison were the accumulated dose averaged along the rotation axis (D(i)), the volume average dose,D(vol) for the dosimetric phantom, the dose area product (DAP) and the absorbed dose for the TLDs. Absolute differences between measured and simulated outcomes were ≤ 2.1% for free-in-air doses; ≤ 6.2% in the 5 cavities of the CT dose head phantom; ≤ 13% for TLDs inside the primary beam. Such differences were considered acceptable in all cases and confirmed the validity of the MC program for different geometries. In conclusion, the devised MC simulation program can be a robust tool to optimize protocols and estimate patient doses for CBCT units in dental, oral and maxillofacial radiology.
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Pawlowski JM, Ding GX. A new approach to account for the medium-dependent effect in model-based dose calculations for kilovoltage x-rays. Phys Med Biol 2011; 56:3919-34. [DOI: 10.1088/0031-9155/56/13/011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kouznetsov A, Tambasco M. A hybrid approach for rapid, accurate, and direct kilovoltage radiation dose calculations in CT voxel space. Med Phys 2011; 38:1378-88. [DOI: 10.1118/1.3555038] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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