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Clements N, Bazalova-Carter M. Monte Carlo calculated absorbed-dose energy dependence of EBT3 and EBT4 films for 5-200 MeV electrons and 100 keV-15 MeV photons. J Appl Clin Med Phys 2024:e14529. [PMID: 39269999 DOI: 10.1002/acm2.14529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 07/30/2024] [Accepted: 08/08/2024] [Indexed: 09/15/2024] Open
Abstract
PURPOSE To use Monte Carlo simulations to study the absorbed-dose energy dependence of GAFChromic EBT3 and EBT4 films for 5-200 MeV electron beams and 100 keV-15 MeV photon beams considering two film compositions: a previous EBT3 composition (Bekerat et al.) and the final composition of EBT3/current composition of EBT4 (Palmer et al.). METHODS A water phantom was simulated with films at 5-50 mm depth in 5 mm intervals. The water phantom was irradiated with flat, monoenergetic 5-200 MeV electron beams and 100 and 150 keV kilovoltage and 1-15 MeV megavoltage photon beams and the dose to the active layer of the films was scored. Simulations were rerun with the films defined as water to compare the absorbed-dose response of film to water,f - 1 ( Q ) = D f i l m D w a t e r $f^{-1}(Q)=\frac{D_{film}}{D_{water}}$ . RESULTS For electrons, the Bekerat et al. composition had variations inf - 1 ( Q ) $f^{-1}(Q)$ of up to( 1.9 ± 0.1 ) % $(1.9\,\pm \,0.1)\%$ from 5 to 200 MeV. Similarly, the Palmer et al. composition had differences inf - 1 ( Q ) $f^{-1}(Q)$ up to( 2.5 ± 0.2 ) % $(2.5 \pm 0.2)\%$ from 5 to 200 MeV. For photons,f - 1 ( Q ) $f^{-1}(Q)$ varied up to( 2.4 ± 0.3 ) % $(2.4 \pm 0.3)\%$ and( 4.5 ± 0.7 ) % $(4.5 \pm 0.7)\%$ from 100 keV to 15 MeV for the Bekerat et al. and Palmer et al. compositions, respectively. The depth of films did not appear to significantly affectf - 1 ( Q ) $f^{-1}(Q)$ for photons at any energy and for electrons at energies > $>$ 50 MeV. However, for 5 and 10 MeV electrons, decreases of up to( 10.2 ± 1.1 ) % $(10.2 \pm 1.1)\%$ inf - 1 ( Q ) $f^{-1}(Q)$ were seen due to stacked films and increased beam attenuation in films compared to water. CONCLUSIONS The up to( 2.5 ± 0.2 ) % $(2.5 \pm 0.2)\%$ and( 4.5 ± 0.7 ) % $(4.5 \pm 0.7)\%$ variations inf - 1 ( Q ) $f^{-1}(Q)$ for electrons and photons, respectively, across the energies considered in this study indicate the importance of calibrating films with the energy intended for measurement. Additionally, this work emphasizes potential issues with stacking films to measure depth dose curves, particularly for electron beams with energies ≤ $\le$ 10 MeV.
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Affiliation(s)
- Nathan Clements
- Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada
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Kozicki M, Sąsiadek-Andrzejczak E, Wach R, Maras P. Flexible Cotton Fabric-Based Ionizing Radiation Dosimeter for 2D Dose Distribution Measurements over a Wide Dose Range at High Dose Rates. Int J Mol Sci 2024; 25:2916. [PMID: 38474163 DOI: 10.3390/ijms25052916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 03/14/2024] Open
Abstract
This work presents an ecological, flexible 2D radiochromic dosimeter for measuring ionizing radiation in the kilogray dose range. Cotton woven fabric made of cellulose was volume-modified with nitrotetrazolium blue chloride as a radiation-sensitive compound. Its features include a color change during exposure from yellowish to purple-brown and flexibility that allows it to adapt to various shapes. It was found that (i) the dose response is up to ~80 kGy, (ii) it is independent of the dose rate for 1.1-73.1 kGy/min, (iii) it can be measured in 2D using a flatbed scanner, (iv) the acquired images can be filtered using a mean filter, which improves its dose resolution, (v) the dose resolution is -0.07 to -0.4 kGy for ~0.6 to ~75.7 kGy for filtered images, and (vi) two linear dose subranges can be distinguished: ~0.6 to ~7.6 kGy and ~9.9 to ~62.0 kGy. The dosimeter combined with flatbed scanner reading and data processing using dedicated software packages constitutes a comprehensive system for measuring dose distributions for objects with complex shapes.
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Affiliation(s)
- Marek Kozicki
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, Żeromskiego 116, 90-543 Lodz, Poland
| | - Elżbieta Sąsiadek-Andrzejczak
- Department of Mechanical Engineering, Informatics and Chemistry of Polymer Materials, Faculty of Materials Technologies and Textile Design, Lodz University of Technology, Żeromskiego 116, 90-543 Lodz, Poland
| | - Radosław Wach
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland
| | - Piotr Maras
- Department of Radiotherapy Planning, Copernicus Hospital, Pabianicka 62, 93-513 Lodz, Poland
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Liu K, Jorge PG, Tailor R, Moeckli R, Schüler E. Comprehensive evaluation and new recommendations in the use of Gafchromic EBT3 film. Med Phys 2023; 50:7252-7262. [PMID: 37403570 PMCID: PMC10766858 DOI: 10.1002/mp.16593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 06/06/2023] [Accepted: 06/11/2023] [Indexed: 07/06/2023] Open
Abstract
BACKGROUND Gafchromic film's unique properties of tissue-equivalence, dose-rate independence, and high spatial resolution make it an attractive choice for many dosimetric applications. However, complicated calibration processes and film handling limits its routine use. PURPOSE We evaluated the performance of Gafchromic EBT3 film after irradiation under a variety of measurement conditions to identify aspects of film handling and analysis for simplified but robust film dosimetry. METHODS The short- (from 5 min to 100 h) and long-term (months) film response was evaluated for clinically relevant doses of up to 50 Gy for accuracy in dose determination and relative dose distributions. The dependence of film response on film-read delay, film batch, scanner type, and beam energy was determined. RESULTS Scanning the film within a 4-h window and using a standard 24-h calibration curve introduced a maximum error of 2% over a dose range of 1-40 Gy, with lower doses showing higher uncertainty in dose determination. Relative dose measurements demonstrated <1 mm difference in electron beam parameters such as depth of 50% of the maximum dose value (R50 ), independent of when the film was scanned after irradiation or the type of calibration curve used (batch-specific or time-specific calibration curve) if the same default scanner was used. Analysis of films exposed over a 5-year period showed that using the red channel led to the lowest variation in the measured net optical density values for different film batches, with doses >10 Gy having the lowest coefficient of variation (<1.7%). Using scanners of similar design produced netOD values within 3% after exposure to doses of 1-40 Gy. CONCLUSIONS This is the first comprehensive evaluation of the temporal and batch dependence of Gafchromic EBT3 film evaluated on consolidated data over 8 years. The relative dosimetric measurements were insensitive to the type of calibration applied (batch- or time-specific) and in-depth time-dependent dosimetric signal behaviors can be established for film scanned outside of the recommended 16-24 h post-irradiation window. We generated guidelines based on our findings to simplify film handling and analysis and provide tabulated dose- and time-dependent correction factors to achieve this without reducing the accuracy of dose determination.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Ramesh Tailor
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
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Chan MF, Park J, Aydin R, Lim SB. Technical note: Energy dependence of the Gafchromic EBT4 film: Dose-response curves for 70 kV, 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV x-ray beams. Med Phys 2023; 50:3738-3745. [PMID: 36695666 PMCID: PMC10635410 DOI: 10.1002/mp.16240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND EBT4 was newly released for radiotherapy quality assurance to improve the signal-to-noise ratio in radiochromic film dosimetry. It is important to know its dose-response characteristics before its use in the clinic. PURPOSE This study aims to investigate and compare the dose-response curves of the Gafchromic EBT4 film for megavoltage and kilovoltage x-ray beams with different dose levels, scanning spatial resolutions, and sizes of region of interest (ROI). METHODS EBT4 film (Lot#07052201) calibration strips (3.5 × 20 cm2 ) were exposed to a 10×10 cm2 open field at doses of 0, 63, 125, 500, 750, 1000 cGy using 6 MV photon beam. EBT4 film strips from the same lot were then exposed to each x-ray beam (6 MV, 6 MV FFF, 10 MV FFF, 15 MV, and 70 kV) at six dose values (50, 100, 300, 600, 800, 1000 cGy). A full sheet (25 × 20 cm2 ) of EBT4 film was irradiated at each energy with 300 cGy for profile comparison with the treatment planning calculation. At two different spatial resolutions of 72 and 300 dpi, each film piece was scanned three consecutive times in the center of an Epson 10000XL flatbed scanner in 48-bit color. The scanned images were analyzed using FilmQA Pro. For each scanned image, an ROI of 2 × 2 cm2 at the field center was selected to obtain the average pixel value with its standard deviation in the ROI. An additional ROI of 1 cm diameter circle was also used to evaluate the impact of ROI shape and size, especially for FFF beams. The dose value, average dose-response value, and associated uncertainty were determined for each energy and relative responses were analyzed. The Student's t-test was performed to evaluate the statistical significance of the dose-response values with different color channels, ROI shapes, and spatial resolutions. RESULTS The dose-response curves for the five x-ray energies were compared in three color channels. Weak energy dependence was found among the megavoltage beams. No significant differences (average ∼1.1%) were observed for all doses in this study among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV beams, regardless of spatial resolution and color channel. However, a statistically significant difference in dose-response was observed up to 12% between 70 kV and 6 MV beams. CONCLUSIONS The dose-response curves for Gafchromic EBT4 films were nearly independent of the energy of the photon beams among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV. For very low-energy photons (e.g., 70 kV), a separate calibration from the same low-energy x-ray is necessary.
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Affiliation(s)
- Maria F. Chan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Jeonghoon Park
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | | | - Seng-Boh Lim
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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Lommen J, Schorn L, Sproll C, Kerkfeld V, Aksu A, Reinauer F, Kübler NR, Budach W, Rana M, Tamaskovics B. Metallic Artifact Reduction in Midfacial CT Scans Using Patient-Specific Polymer Implants Enhances Image Quality. J Pers Med 2023; 13:236. [PMID: 36836470 PMCID: PMC9958634 DOI: 10.3390/jpm13020236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/22/2023] [Accepted: 01/27/2023] [Indexed: 02/03/2023] Open
Abstract
Midfacial reconstruction after tumor resection surgery is commonly conducted by using autologous bone grafts or alloplastic implants. Titanium is the most frequently used osteosynthesis material in these cases but causes disturbing metallic artifacts in CT imaging. The purpose of this experimental study was to evaluate whether the use of midfacial polymer implants reduces metallic artifacts in CT imaging to improve image quality. Zygomatic titanium (n = 1) and polymer (n = 12) implants were successively implanted in a human skull specimen. Implants were analyzed for their effect on Hounsfield Unit values (streak artifacts) and virtual growth in CT images (blooming artifacts) as well as image quality. Multi-factorial ANOVA and Bonferroni's post hoc test were used. Titanium (173.7 HU; SD ± 5.1) and hydroxyapatite containing polymers (155.3 HU; SD ± 5.9) were associated with significantly more streak artifacts compared to all other polymer materials. There was no significant difference in blooming artifacts between materials. The metallic artifact reduction algorithm showed no significant difference. Image quality was slightly better for polymer implants compared to titanium. Personalized polymer implants for midfacial reconstruction significantly reduce metallic artifacts in CT imaging which improves image quality. Hence, postoperative radiation therapy planning and radiological tumor aftercare around the implants are facilitated.
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Affiliation(s)
- Julian Lommen
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Lara Schorn
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Christoph Sproll
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Valentin Kerkfeld
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Adem Aksu
- Karl Leibinger Medizintechnik GmbH & Co. KG, Kolbinger Str. 10, 78570 Mühlheim, Germany
| | - Frank Reinauer
- Karl Leibinger Medizintechnik GmbH & Co. KG, Kolbinger Str. 10, 78570 Mühlheim, Germany
| | - Norbert R. Kübler
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Wilfried Budach
- Department of Radiation Oncology, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Majeed Rana
- Department of Oral, Maxillofacial and Facial Plastic Surgery, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Bálint Tamaskovics
- Department of Radiation Oncology, University Hospital Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
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Stepanek CJ, Haynes JA, Fletcher S. Evaluation of a complementary metal oxide semiconductor detector as a tool for stereotactic body radiotherapy plan quality assurance. Phys Imaging Radiat Oncol 2023; 25:100418. [PMID: 36755894 PMCID: PMC9900433 DOI: 10.1016/j.phro.2023.100418] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
Background and purpose A sub-mm resolution Complementary Metal Oxide Semiconductor sensor has been developed for stereotactic radiotherapy quality assurance. Herein we evaluate its basic dosimetric performance and its application for linac C-arm stereotactic body radiotherapy (SBRT) plan quality assurance. Materials and methods The detector was integrated into its accompanying phantom or in Water Equivalent Plastic (WEP). The measurement reproducibility, stability, dose linearity and dependence on angularity, dose rate and field size were investigated. Clinical plan measurements were compared to our radiotherapy treatment planning system and radiochromic film. Sensitivity to introduced Multi Leaf Collimator (MLC) offsets was evaluated by simulating single MLC offsets in SBRT plans and comparing measurements to expected doses. Results Signal reproducibility was within ± 0.1 % and output calibration was stable over a 6 month period. Detector showed good linearity with dose (r2 = 1). Signal decreased by 5 % when dose rate was decreased from 1300 MU/min to 300 MU/min. Output factors agreed within 0.5 % of chamber measurements for 1x1 cm field sizes or greater. Angularity measurements showed good agreement with reference. For measurement of planned clinical doses, gamma pass-rates were 98.5 % ± 2.3 % (treatment planning system reference, 2 %/2mm) and 99.2 % ± 1.0 % (film reference, 2 %,2mm). The detector also showed sensitivity to errors of 1 mm offsets in MLC positioning. Conclusion The detector performed well when used for pre-treatment SBRT plan quality assurance, offering a good alternative to radiochromic film.
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Lim SB, Tang G. Evaluation of OrthoChromic OC-1 films for photon radiotherapy application. JOURNAL OF RADIATION RESEARCH 2023; 64:105-112. [PMID: 36453442 PMCID: PMC9855338 DOI: 10.1093/jrr/rrac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/07/2022] [Indexed: 06/17/2023]
Abstract
A new film dosimetry system consists of the new OrthoChromic™ OC-1 film, and a novel calibration procedure was evaluated. Two films, C1 and C2, were exposed simultaneously using the 6FFF beam with a step-wedge pattern of five steps ranging from 590 to 3000 cGy. C1 was used for calibration, and C2 was used for calibration curve validation. The second scan of C2 was done by rotating the film by 90-deg. To evaluate the effectiveness of the non-uniform scanner response correction with the new system, a film was exposed to a 20 × 20 cm2 field. The beam profile measured with the film was compared to the IBA cc04 measurements in water. Films were irradiated to characterize the energy response, dynamic range and temporal growth effect. Open (MLC-defined) and clinical fields were radiated to evaluate the overall performance of the new system. The new calibration procedure was validated with an average dose difference of 1.6% and a gamma (2%,2 mm) passing rate of 100%. With C2 scanned 90-deg rotated, the average dose difference was 1.3%. The average difference between cc04 and film was 0.4%. The St between films and diode/cc04 were within -0.3% difference for 1 × 1 to 14 × 14 cm2 and -2.8% for 0.5 × 0.5 cm2. For clinical fields, the average gamma (3%,2 mm) was 98.8%. These results were consistent with EBT3 film and MapCheck measurements with a dose > 400 cGy. The results have shown that the OC-1 film system can achieve accurate results for QA measurements, but more considerable uncertainty was observed within the low dose range.
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Affiliation(s)
- Seng Boh Lim
- Corresponding author. Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, New York 10065, USA. E-mail:
| | - Grace Tang
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, New York 10065, USA
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Kozicki M, Maras P. Features of 2Day.QA® as a 2D radiation dosimeter. Phys Med 2022; 104:23-31. [PMID: 36356501 DOI: 10.1016/j.ejmp.2022.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 09/21/2022] [Accepted: 10/22/2022] [Indexed: 11/11/2022] Open
Abstract
PURPOSE A new commercial 2D ionising radiation dosimeter (2Day.QA®) was developed. This work aims to introduce the basic functions of 2Day.QA®. METHODS The dosimeter is made mainly of a linear polysaccharide consisting of β(1 → 4) linked d-glucose units and radiation active substances, which make it environmentally friendly. For 2Day.QA® irradiation, radiotherapy ionising radiation sources were used. The analysis of 2Day.QA® was performed using three scanners: Vidar® Red LED Dosimetry Pro Advantage™, Vidar® VXR 12-plus™ and HP Scanjet G3010 flatbed scanner. The stability of 2Day.QA® was tested. Exemplary applications of 2DayQA® for QA studies of accelerator light and radiation field coincidence and brachytherapy source position were carried out. RESULTS The dosimeter responded to the lowest applied dose of 0.95 Gy and saturated at over 94.9 Gy. The quasi-linear dose response is below 20 Gy. Vidar® Red LED Dosimetry Pro Advantage™ has proven to be superior to other scanners at determining dose effects in 2Day.QA®. The stability of the non-irradiated 2Day.QA® is at least 18 months. After 18 months of storage, the dosimeter reacted to irradiation. In the case of the irradiated samples, a slight color drift related to the absorbed dose was observed. Tests of the use of 2Day.QA® to control the quality of the accelerator light and radiation field coincidence and brachytherapy source position have shown that it can be used for such applications. CONCLUSIONS The study reveals the potential of 2Day.QA® for 2D radiation dosimetry and concludes with recommendations for the use of the dosimeter for radiotherapy QA tests.
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Lommen J, Schorn L, Sproll C, Haussmann J, Kübler NR, Budach W, Rana M, Tamaskovics B. Reduction of CT artifacts using polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylsulfone (PPSU) and polyethylene (PE) reconstruction plates in oral oncology. J Oral Maxillofac Surg 2022; 80:1272-1283. [DOI: 10.1016/j.joms.2022.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/06/2022] [Accepted: 03/03/2022] [Indexed: 10/18/2022]
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Li J, Zhang X, Pan Y, Zhuang H, Wang J, Yang R. Assessment of Delivery Quality Assurance for Stereotactic Radiosurgery With Cyberknife. Front Oncol 2021; 11:751922. [PMID: 34868957 PMCID: PMC8635503 DOI: 10.3389/fonc.2021.751922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/26/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose The purpose of this study is to establish and assess a practical delivery quality assurance method for stereotactic radiosurgery with Cyberknife by analyzing the geometric and dosimetric accuracies obtained using a PTW31016 PinPoint ionization chamber and EBT3 films. Moreover, this study also explores the relationship between the parameters of plan complexity, target volume, and deliverability parameters and provides a valuable reference for improving plan optimization and validation. Methods One hundred fifty cases of delivery quality assurance plans were performed on Cyberknife to assess point dose and planar dose distribution, respectively, using a PTW31016 PinPoint ionization chamber and Gafchromic EBT3 films. The measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber, and the measured planar doses were compared with the calculated dose distribution using gamma index analysis. The gamma passing rates were evaluated using the criteria of 3%/1 mm and 2%/2 mm. The statistical significance of the correlations between the complexity metrics, target volume, and the gamma passing rate were analyzed using Spearman’s rank correlation coefficient. Results For point dose comparison, the averaged dose differences (± standard deviations) were 1.6 ± 0.73% for all the cases. For planar dose distribution, the mean gamma passing rate for 3%/1 mm, and 2%/2 mm evaluation criteria were 94.26% ± 1.89%, and 93.86% ± 2.16%, respectively. The gamma passing rates were higher than 90% for all the delivery quality assurance plans with the criteria of 3%/1 mm and 2%/2 mm. The difference in point dose was lowly correlated with volume of PTV, number of beams, and treatment time for 150 DQA plans, and highly correlated with volume of PTV for 18 DQA plans of small target. DQA gamma passing rate (2%/2 mm) was a moderate significant correlation for the number of nodes, number of beams and treatment time, and a low correlation with MU. Conclusion PTW31016 PinPoint ionization chamber and EBT3 film can be used for routine Cyberknife delivery quality assurance. The point dose difference should be within 3%. The gamma passing rate should be higher than 90% for the criteria of 3%/1 mm and 2%/2 mm. In addition, the plan complexity and PTV volume were found to have some influence on the plan deliverability.
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Affiliation(s)
- Jun Li
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
| | - Xile Zhang
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
| | - Yuxi Pan
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
| | - Hongqing Zhuang
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
| | - Junjie Wang
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
| | - Ruijie Yang
- Department of Radiation Oncology, Peking University Third Hospital, Beijing, China
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Xhaferllari I, Kim JP, Liyanage R, Liu C, Du D, Doemer A, Chetty IJ, Wen N. Clinical utility of Gafchromic film in an MRI-guided linear accelerator. Radiat Oncol 2021; 16:117. [PMID: 34174932 PMCID: PMC8236160 DOI: 10.1186/s13014-021-01844-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/15/2021] [Indexed: 11/18/2022] Open
Abstract
Background The purpose of this study is to comprehensively evaluate the suitability of Gafchromic EBT3 and EBT-XD film for dosimetric quality assurance in 0.35 T MR-guided radiotherapy. Methods A 0.35 T magnetic field strength was utilized to evaluate magnetic field effects on EBT3 and EBT-XD Gafchromic films by studying the effect of film exposure time within the magnetic field using two timing sequences and film not exposed to MR, the effect of magnetic field exposure on the crystalline structure of the film, and the effect of orientation of the film with respect to the bore within the magnetic field. The orientation of the monomer crystal was qualitatively evaluated using scanning electron microscopy (SEM) compared to unirradiated film. Additionally, dosimetric impact was evaluated through measurements of a series of open field irradiations (0.83 × 0.83-cm2 to 19.92 × 19.92-cm2) and patient specific quality assurance measurements. Open fields were compared to planned dose and an independent dosimeter. Film dosimetry was applied to twenty conventional and twenty stereotactic body radiotherapy (SBRT) patient specific quality assurance cases. Results No visual changes in crystal orientation were observed in any evaluated SEM images nor were any optical density differences observed between films irradiated inside or outside the magnetic field for both EBT3 and EBT-XD film. At small field sizes, the average difference along dose profiles measured in film compared to the same points measured using an independent dosimeter and to predicted treatment planning system values was 1.23% and 1.56%, respectively. For large field sizes, the average differences were 1.91% and 1.21%, respectively. In open field tests, the average gamma pass rates were 99.8% and 97.2%, for 3%/3 mm and 3%/1 mm, respectively. The median (interquartile range) 3%/3 mm gamma pass rates in conventional QA cases were 98.4% (96.3 to 99.2%), and 3%/1 mm in SBRT QA cases were 95.8% (95.0 to 97.3%). Conclusions MR exposure at 0.35 T had negligible effects on EBT3 and EBT-XD Gafchromic film. Dosimetric film results were comparable to planned dose, ion chamber and diode measurements.
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Affiliation(s)
- Ilma Xhaferllari
- Department of Radiation Oncology, Beaumont Health, Troy, MI, USA
| | - Joshua P Kim
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Ruchira Liyanage
- Department of Chemical Engineering and Material Science, Wayne State University, Detroit, MI, USA
| | - Chang Liu
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Dongsu Du
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Anthony Doemer
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Indrin J Chetty
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA
| | - Ning Wen
- Department of Radiation Oncology, Henry Ford Health System, 2799 West Grand Blvd, Detroit, MI, USA.
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12
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Holm KM, Yukihara EG, Ahmed MF, Greilich S, Jäkel O. Triple channel analysis of Gafchromic EBT3 irradiated with clinical carbon-ion beams. Phys Med 2021; 87:123-130. [PMID: 34146794 DOI: 10.1016/j.ejmp.2021.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 06/03/2021] [Accepted: 06/05/2021] [Indexed: 11/16/2022] Open
Abstract
Self-developing radiochromic film is widely used in radiotherapy QA procedures. To compensate for typical film inhomogeneities, the triple channel analysis method is commonly used for photon-irradiated film. We investigated the applicability of this method for GafchromicTMEBT3 (Ashland) film irradiated with a clinically used carbon-ion beam. Calibration curves were taken from EBT3 film specimens irradiated with monoenergetic carbon-ion beams of different doses. Measurements of the lateral field shape and homogeneity were performed in the middle of a passively modulated spread-out Bragg peak and compared to simultaneous characterization by means of a 2D ionization chamber array. Additional measurements to investigate the applicability of EBT3 for quality assurance (QA) measurement in carbon-ion beams were performed. The triple-channel analysis reduced the relative standard deviation of the doses in a uniform carbon ion field by 30% (from 1.9% to 1.3%) and reduced the maximum deviation by almost a factor of 3 (from 28.6% to 9.8%), demonstrating the elimination of film artifacts. The corrected film signal showed considerably improved image quality and quantitative agreement with the ionization chamber data, thus providing a clear rationale for the usage of the triple channel analysis in carbon-beam QA.
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Affiliation(s)
- Kim Marina Holm
- Department of Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany; Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany; Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Department of Physics and Astronomy, Heidelberg University, Im Neuenheimer Feld 226, Heidelberg D-69120, Germany.
| | - Eduardo G Yukihara
- Department of Radiation Safety and Security, Paul Scherrer Institute, Forschungsstrasse 111, Villigen PSI 5232, Switzerland
| | - Md Foiez Ahmed
- Sun Nuclear Corporation, 3275 Suntree Blvd, Melbourne, Florida 32940, USA
| | - Steffen Greilich
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany; Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany
| | - Oliver Jäkel
- Department of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany; Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany; Heidelberg Ion Beam Therapy Center (HIT), University Hospital Heidelberg, Im Neuenheimer Feld 450, Heidelberg D-69120, Germany
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13
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Hall AV, Musa OM, Hood DK, Apperley DC, Yufit DS, Steed JW. Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications. CRYSTAL GROWTH & DESIGN 2021. [PMID: 34054354 DOI: 10.1021/acs.cgd.1c00300] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA-a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its short needle-shaped crystals, which provide favorable coating properties. Form B provides an enhanced photoresponse compared to that of form A, but adopts a long needle crystal morphology, which is difficult to process. The two forms were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, CP-MAS 13C solid-state NMR spectroscopy, and thermogravimetric analysis. In sum, these data suggest a chelating bridging bidentate coordination mode for the lithium ions. The sodium salt of PCDA (Na-PCDA) is also reported, which is an ionic cocrystal with a formula of Na+PCDA-·3PCDA. The PCDA and PCDA- ligands display monodentate and bridging bidentate coordination to the sodium ion in contrast to the coordination sphere of the Li-PCDA forms. In contrast to its lithium analogues, Na-PCDA is photostable.
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Affiliation(s)
- Amy V Hall
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Osama M Musa
- Ashland LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David K Hood
- Ashland LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David C Apperley
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Dmitry S Yufit
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Jonathan W Steed
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
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14
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Hall AV, Musa OM, Hood DK, Apperley DC, Yufit DS, Steed JW. Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications. CRYSTAL GROWTH & DESIGN 2021; 21:2416-2422. [PMID: 34054354 PMCID: PMC8154271 DOI: 10.1021/acs.cgd.1c00031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/17/2021] [Indexed: 05/22/2023]
Abstract
Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA-a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its short needle-shaped crystals, which provide favorable coating properties. Form B provides an enhanced photoresponse compared to that of form A, but adopts a long needle crystal morphology, which is difficult to process. The two forms were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, CP-MAS 13C solid-state NMR spectroscopy, and thermogravimetric analysis. In sum, these data suggest a chelating bridging bidentate coordination mode for the lithium ions. The sodium salt of PCDA (Na-PCDA) is also reported, which is an ionic cocrystal with a formula of Na+PCDA-·3PCDA. The PCDA and PCDA- ligands display monodentate and bridging bidentate coordination to the sodium ion in contrast to the coordination sphere of the Li-PCDA forms. In contrast to its lithium analogues, Na-PCDA is photostable.
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Affiliation(s)
- Amy V. Hall
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Osama M. Musa
- Ashland
LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David K. Hood
- Ashland
LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David C. Apperley
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Dmitry S. Yufit
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Jonathan W. Steed
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
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Calibration of the EBT3 Gafchromic Film Using HNN Deep Learning. BIOMED RESEARCH INTERNATIONAL 2021; 2021:8838401. [PMID: 33628820 PMCID: PMC7892216 DOI: 10.1155/2021/8838401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/22/2020] [Accepted: 01/17/2021] [Indexed: 11/19/2022]
Abstract
To achieve a dose distribution conformal to the target volume while sparing normal tissues, intensity modulation with steep dose gradient is used for treatment planning. To successfully deliver such treatment, high spatial and dosimetric accuracy are crucial and need to be verified. With high 2D dosimetry resolution and a self-development property, the Ashland Inc. product EBT3 Gafchromic film is a widely used quality assurance tool designed especially for this. However, the film should be recalibrated each quarter due to the “aging effect,” and calibration uncertainties always exist between individual films even in the same lot. Recently, artificial neural networks (ANN) are applied to many fields. If a physicist can collect the calibration data, it could be accumulated to be a substantial ANN data input used for film calibration. We therefore use the Keras functional Application Program Interface to build a hierarchical neural network (HNN), with the inputs of net optical densities, pixel values, and inverse transmittances to reveal the delivered dose and train the neural network with deep learning. For comparison, the film dose calculated using red-channel net optical density with power function fitting was performed and taken as a conventional method. The results show that the percentage error of the film dose using the HNN method is less than 4% for the aging effect verification test and less than 4.5% for the intralot variation test; in contrast, the conventional method could yield errors higher than 10% and 7%, respectively. This HNN method to calibrate the EBT film could be further improved by adding training data or adjusting the HNN structure. The model could help physicists spend less calibration time and reduce film usage.
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16
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Chaudhary RK, Pathan M, Kumar R, Sharma SD, Sapra BK. Probability Distribution of Pixel Intensities of EBT3 Films and its Application in the Correction of Uncertainty Budget. J Med Phys 2021; 46:26-32. [PMID: 34267486 PMCID: PMC8240913 DOI: 10.4103/jmp.jmp_94_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND AND AIM Modern radiotherapy modalities, such as Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy involve complex dose delivery. The dose delivery is complex as it involves beam modulation, hence, manual dose calculations for these techniques are not possible. Film dosimetry is commonly used method of dose verification for these modalities because of the advantages associated with it. The quantification of uncertainty associated with a film dosimetry system under clinical use becomes important for accurate dosimetry. The spread in the distribution of the pixel values (PV) of the irradiated film contributes to the uncertainty. The probability distribution (PD) of the PV was studied for the clinical photon beam energies of 6, 10, and 15 MV. METHODS AND MATERIALS Gafchromic EBT3 film and EPSON 10000XL flatbed scanner were used for this purpose and using the resulting PD, the uncertainty budgets for these energies in the red, green and blue color channels were estimated. RESULTS The PV of exposed films for the energies studied follows t-distribution, the sum of the squares of the deviation of the measured data from the fitted value was of the order of 10-7, this indicates the goodness of fit. The "t" value corrected combined standard uncertainty (CSU) at 1σ confidence level for exposed film and dose measurement at 200 cGy were 1.42%, 1.48%, and 1.63% and 1.99%, 3.23%, and 5.08% for 6, 10, and 15 MV energies, respectively, in the red colour channel. CONCLUSION In the case of the limited number of measurements of a quantity, the SU values must be corrected using the "t" value to get the correct CSU.
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Affiliation(s)
- Rahul Kumar Chaudhary
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Munir Pathan
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Rajesh Kumar
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - S. D. Sharma
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Mumbai, Maharashtra, India
| | - B. K. Sapra
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Mumbai, Maharashtra, India
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17
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Niroomand‐Rad A, Chiu‐Tsao S, Grams MP, Lewis DF, Soares CG, Van Battum LJ, Das IJ, Trichter S, Kissick MW, Massillon‐JL G, Alvarez PE, Chan MF. Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55. Med Phys 2020; 47:5986-6025. [DOI: 10.1002/mp.14497] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Affiliation(s)
| | | | | | | | | | | | - Indra J. Das
- Radiation Oncology Northwestern University Memorial Hospital Chicago IL USA
| | - Samuel Trichter
- New York‐Presbyterian HospitalWeill Cornell Medical Center New York NY USA
| | | | - Guerda Massillon‐JL
- Instituto de Fisica Universidad Nacional Autonoma de Mexico Mexico City Mexico
| | - Paola E. Alvarez
- Imaging and Radiation Oncology Core MD Anderson Cancer Center Houston TX USA
| | - Maria F. Chan
- Memorial Sloan Kettering Cancer Center Basking Ridge NJ USA
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18
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Yap J, Resta-López J, Kacperek A, Schnuerer R, Jolly S, Boogert S, Welsch C. Beam characterisation studies of the 62 MeV proton therapy beamline at the Clatterbridge Cancer Centre. Phys Med 2020; 77:108-120. [DOI: 10.1016/j.ejmp.2020.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/15/2020] [Accepted: 08/03/2020] [Indexed: 10/23/2022] Open
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Nguyen J, Pejović-Milić A, Gräfe JL. Investigating coherent normalization and dosimetry for the 241Am-La K XRF system. Physiol Meas 2020; 41:075014. [PMID: 32392547 DOI: 10.1088/1361-6579/ab921f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Lanthanum (La) retention in bone has been shown to occur in individuals who are orally administered lanthanum carbonate (LaC), a drug to treat hyperphosphatemia. The breakdown of LaC in the gastrointestinal tract into La3+ and carbonate ions results in residual quantities of La being deposited in bone. We previously reported on a non-invasive x-ray fluorescence (XRF) system that was developed to quantify bone La concentrations and applied it to a series of excised cadaver tibiae. However, given interpatient variability in bone shape and size, differential signal attenuation that occurs in bone and tissue, patient movement and overlying tissue thickness at the measurement site, quantifying bone La concentrations during in vivo measurements in live subjects needs to be investigated further along with the radiation dose associated with the measurement. APPROACH Coherent normalization was investigated as a function of overlying tissue thickness, source-subject distance and bone radius through Monte Carlo simulation and experimental work. This was accomplished by observing the ratio of the net La K x-ray peak area to the coherently scattered peak area at 59.5 keV. In addition, the dose delivered during a 2000 s measurement was determined using radiochromic film. MAIN RESULTS The coherent normalization of the La x-ray signal was shown to be independent of overlying tissue thickness, source-subject movement and bone radius, which indicates that this normalization procedure can correct for these factors. The equivalent skin dose and effective dose were 18.0 mSv and 3.2 μSv, respectively for a five-year-old. SIGNIFICANCE While coherent normalization for the bone lead (Pb) and bone gadolinium (Gd) systems has been shown to be successful, we also report that this normalization procedure can correct for these interpatient variabilities in the in vivo 241Am-La K XRF system.
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Affiliation(s)
- Joanna Nguyen
- Department of Physics, Ryerson University, 350 Victoria St., Toronto, Ontario, M5B 2K3, Canada
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20
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Howard ME, Herman MG, Grams MP. Methodology for radiochromic film analysis using FilmQA Pro and ImageJ. PLoS One 2020; 15:e0233562. [PMID: 32437474 PMCID: PMC7241712 DOI: 10.1371/journal.pone.0233562] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 05/07/2020] [Indexed: 11/23/2022] Open
Abstract
Radiochromic film (RCF) has several advantageous characteristics which make it an attractive dosimeter for many clinical tasks in radiation oncology. However, knowledge of and strict adherence to complicated protocols in order to produce accurate measurements can prohibit RCF from being widely adopted in the clinic. The purpose of this study was to outline some simple and straightforward RCF fundamentals in order to help clinical medical physicists perform accurate RCF measurements. We describe a process and methodology successfully used in our practice with the hope that it saves time and effort for others when implementing RCF in their clinics. Two RCF analysis software programs which differ in cost and complexity, the commercially available FilmQA Pro package and the freely available ImageJ software, were used to show the accuracy, consistency and limitations of each. The process described resulted in a majority of the measurements across a wide dose range to be accurate within ± 2% of the intended dose using either FilmQA Pro or ImageJ.
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Affiliation(s)
- Michelle E. Howard
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Michael G. Herman
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Michael P. Grams
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, United States of America
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21
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Monte Carlo calculated output correction factors for Gafchromic EBT3 film for relative dosimetry in small stereotactic radiosurgery fields. Phys Eng Sci Med 2020; 43:609-616. [DOI: 10.1007/s13246-020-00860-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 03/17/2020] [Indexed: 10/24/2022]
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22
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Carbon Fiber/Polyether Ether Ketone (CF/PEEK) Implants Allow for More Effective Radiation in Long Bones. MATERIALS 2020; 13:ma13071754. [PMID: 32283675 PMCID: PMC7178689 DOI: 10.3390/ma13071754] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/03/2020] [Accepted: 04/07/2020] [Indexed: 11/22/2022]
Abstract
Background: Metallic implants show dose-modulating effects in radiotherapy and complicate its computed tomography (CT)-based planning. Dose deviations might not only affect the surrounding tissues due to backscattering and inadvertent dose increase but might also compromise the therapeutic effect to the target lesion due to beam attenuation. Later on, follow-up imaging is often obscured by metallic artefacts. Purposes: This study investigates the dosimetric impact of titanium and radiolucent carbon fiber/polyether ether ketone (CF/PEEK) implants during adjuvant radiation therapy in long bones. (1) Does the use of CF/PEEK implants allow for a more homogenous application of radiation? (2) Is the dose delivery to the target volume more efficient when using CF/PEEK implants? (3) Do CF/PEEK implants facilitate CT-based radiation therapy planning? Materials and methods: After CT-based planning, bone models of six ovine femora were irradiated within a water phantom in two immersion depths to simulate different soft-tissue envelopes. Plates and intramedullary nails of both titanium and CF/PEEK were investigated. Radiation dosage and distribution patterns were mapped using dosimetry films. Results: First, the planned implant-related beam attenuation was lower for the CF/PEEK plate (1% vs. 5%) and the CF/PEEK nail (2% vs. 9%) than for corresponding titanium implants. Secondly, the effective decrease of radiation dosage behind the implants was noticeably smaller when using CF/PEEK implants. The radiation dose was not significantly affected by the amount of surrounding soft tissues. A significant imaging artefact reduction was seen in all CF/PEEK models. Conclusion: CF/PEEK implants lead to a more reliable and more effective delivery of radiation dose to an osseous target volume. With regard to radiation therapy, the use of CF/PEEK implants appears to be particularly beneficial for intramedullary nails.
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Chang L, Ho SY, Ding HJ, Yeh SA, Chen PY. Calibration of Gafchromic EBT Film Using the Microtek ScanMaker 9800XL Plus Flatbed Scanner with a Modified One Red-Channel after Three-Channel Method. J Med Phys 2019; 44:207-212. [PMID: 31576069 PMCID: PMC6764174 DOI: 10.4103/jmp.jmp_45_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose: Using the Microtek ScanMaker 9800XL Plus (9800XL+) flatbed scanner, a method is presented to accurately calibrate EBT film, which cannot be calibrated simply using a general three-channel method because of the nonhomogeneous scanning. Materials and Methods: Through the percentage-depth-dose method, 6-MV photon beams with two different monitor units were delivered to eight EBT2 films, each of which was tightly sandwiched in a 30-cm cubic polystyrene phantom and positioned parallel to the central axis of the beam. Before and after irradiation, all films were scanned using the Microtek 9800XL+ scanner and the pixel values (PVs) were measured along the central axis of the beam on the film and fitted to the corresponding depth doses. Before calibration, the irradiated film image was first modified using a template matrix, which was generated using the prescanned background images. Then, a modified one red-channel after three-channel method was used to calibrate the film. Results: Without a template matrix, the three-channel method cannot be used because the PVs do not correspond to a rational fitting form. Using the proposed method, the difference between the fitted dose and the delivered dose is <2%. The green channel, and not the red, is found to have the largest dynamic range. Conclusion: The proposed technique allows the use of the three-channel method to calibrate film using a Microtek 9800XL+ scanner.
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Affiliation(s)
- Liyun Chang
- Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan
| | - Sheng-Yow Ho
- Department of Nursing, Chang Jung Christian University, Tainan, Taiwan.,Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan
| | - Hueisch-Jy Ding
- Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan
| | - Shyh-An Yeh
- Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan
| | - Pang-Yu Chen
- Department of Radiation Oncology, Sinlau Christian Hospital, Tainan, Taiwan
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24
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Quality assurance of intensity-modulated radiotherapy treatment planning: a dosimetric comparison. JOURNAL OF RADIOTHERAPY IN PRACTICE 2018. [DOI: 10.1017/s1460396918000195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractAimThe purpose of this study was to analyse the comparison of intensity-modulated radiation therapy quality assurance (IMRT QA) using Gafchromic® EBT3 film, Electronic portal imaging device (EPID) and MapCHECK®2.BackgroundPretreatment authentication is the main apprehension in advanced radiation therapy treatment plans such as IMRT.Materials and methodsA total of 20 patients were planned on Eclipse treatment planning system using 6 and 15 MV separately.ResultsGamma index of EBT3 film results shows the following average passing rates: 97% for 6 MV and 96·6% for 15 MV using criteria of ±5% of 3 mm, ±3% of 3 mm and ±3% of 2 mm for brain. However, by using ±5% of 3 mm and ±3% of 3 mm criteria, the average passing rates were 95·4% on 6 MV and 95·2% on 15 MV for prostate. For EPID, the results show the average passing rates as 97·8% for 6 MV and 97·2% for 15 MV in for brain. In cases in which ±5% of 3 mm and ±3% of 3 mm were used, the average passing rates were 96·6% for 6 MVand 96·1% for 15 MV for prostate. MapCHECK®2 results show average passing rates of 96·4% for 6 and 96·2% for 15 MV, respectively, for brain using criteria of ±5% of 3 mm, ±3% of 3 mm and ±3% of 2 mm, whereas for ±5% of 3 mm and ±3% of 3 mm the average rates are 95·2% for 6 and 94·7% for 15 MV in prostate.ConclusionsThe EPID results are better than the other methods, and hence EPID can be used effectively for IMRT pretreatment verifications.
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25
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Giordanengo S, Palmans H. Dose detectors, sensors, and their applications. Med Phys 2018; 45:e1051-e1072. [DOI: 10.1002/mp.13089] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 12/20/2022] Open
Affiliation(s)
- Simona Giordanengo
- Istituto Nazionale di Fisica Nucleare, Section of Torino Via Giuria 1 10125 Torino Italy
| | - Hugo Palmans
- National Physical Laboratory Medical Radiation Science Hampton Road Teddington Middlesex TW11 0LW UK
- EBG MedAustron GmbH Marie‐Curiestraße 5 A‐2700 Wiener Neustadt Austria
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26
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Ade N, du Plessis F. Electron beam dose perturbations caused by diode detectors used for in vivo dosimetry: Gafchromic film dose measurements in a realistic pelvic prosthesis phantom. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.06.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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Mourya A, Aggarwal LM, Mandal A, Shahi UP, Ram C, Asthana AK, Pradhan S. An inexpensive method of small photon field dosimetry with EBT3 radiochromic film. HEALTH AND TECHNOLOGY 2018. [DOI: 10.1007/s12553-018-0233-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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28
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Monaco and film dosimetry of 3D CRT, IMRT and VMAT cases in a realistic pelvic prosthetic phantom. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2017.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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29
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Khachonkham S, Dreindl R, Heilemann G, Lechner W, Fuchs H, Palmans H, Georg D, Kuess P. Characteristic of EBT-XD and EBT3 radiochromic film dosimetry for photon and proton beams. ACTA ACUST UNITED AC 2018; 63:065007. [DOI: 10.1088/1361-6560/aab1ee] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Hermida-López M, Brualla L. Absorbed dose distributions from ophthalmic 106 Ru/ 106 Rh plaques measured in water with radiochromic film. Med Phys 2018; 45:1699-1707. [PMID: 29399810 DOI: 10.1002/mp.12777] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 12/19/2017] [Accepted: 01/06/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Brachytherapy with 106 Ru/106 Rh plaques offers good outcomes for small-to-medium choroidal melanomas and retinoblastomas. The dose measurement of the plaques is challenging, due to the small range of the emitted beta particles and steep dose gradients involved. The scarce publications on film dosimetry of 106 Ru/106 Rh plaques used solid phantoms. This work aims to develop a practical method for measuring the absorbed dose distribution in water produced by 106 Ru/106 Rh plaques using EBT3 radiochromic film. METHODS Experimental setups were developed to determine the dose distribution at a plane perpendicular to the symmetry axis of the plaque and at a plane containing the symmetry axis. One CCA and two CCX plaques were studied. The dose maps were obtained with the FilmQA Pro 2015 software, using the triple-channel dosimetry method. The measured dose distributions were compared to published Monte Carlo simulation and experimental data. RESULTS A good agreement was found between measurements and simulations, improving upon published data. Measured reference dose rates agreed within the experimental uncertainty with data obtained by the manufacturer using a scintillation detector, with typical differences below 5%. The attained experimental uncertainty was 4.1% (k = 1) for the perpendicular setup, and 7.9% (k = 1) for the parallel setup. These values are similar or smaller than those obtained by the manufacturer and other authors, without the need of solid phantoms that are not available to most users. CONCLUSIONS The proposed method may be useful to the users to perform quality assurance preclinical tests of 106 Ru/106 Rh plaques.
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Affiliation(s)
- Marcelino Hermida-López
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany.,Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Lorenzo Brualla
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
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Mao R, Tian L, Zhang Y, Ren L, Gao R, Yin FF, Ge H. Dosimetric Analysis of Microscopic Disease in SBRT for Lung Cancers. Technol Cancer Res Treat 2018; 16:1113-1119. [PMID: 29332497 PMCID: PMC5762078 DOI: 10.1177/1533034617734689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective: The objective of this study is to theoretically and experimentally evaluate the dosimetry in the microscopic disease regions surrounding the tumor under stereotactic body radiation therapy of lung cancer. Methods: For simplicity, the tumor was considered moving along 1 dimension with a periodic function. The probability distribution function of the tumor position was generated according to the motion pattern and was used to estimate the delivered dose in the microscopic disease region. An experimental measurement was conducted to validate both the estimated dose with a probability function and the calculated dose from 4-dimensional computed tomography data using a dynamic thorax phantom. Four tumor motion patterns were simulated with cos4(x) and sin(x), each with 2 different amplitudes: 10 mm and 5 mm. A 7-field conformal plan was created for treatment delivery. Both films (EBT2) and optically stimulated luminescence detectors were inserted in and around the target of the phantom to measure the delivered doses. Dose differences were evaluated using gamma analysis with 3%/3 mm. Results: The average gamma index between measured doses using film and calculated doses using average intensity projection simulation computed tomography was 80.8% ± 0.9%. In contrast, between measured doses using film and calculated doses accumulated from 10 sets of 4-dimensional computed tomography data, it was 98.7% ± 0.6%. The measured doses using optically stimulated luminescence detectors matched very well (within 5% of the measurement uncertainty) with the theoretically calculated doses using probability distribution function at the corresponding position. Respiratory movement caused inadvertent irradiation exposure, with 70% to 80% of the dose line wrapped around the 10 mm region outside the target. Conclusion: The use of static dose calculation in the treatment planning system could substantially underestimate the actual delivered dose in the microscopic disease region for a moving target. The margin for microscopic disease may be substantially reduced or even eliminated for lung stereotactic body radiation therapy.
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Affiliation(s)
- Ronghu Mao
- 1 Department of Radiation Oncology, Henan Cancer Hospital, The Affiliated Cancer Hospital of Zhengzhou University, Henan, China
| | - Lingling Tian
- 1 Department of Radiation Oncology, Henan Cancer Hospital, The Affiliated Cancer Hospital of Zhengzhou University, Henan, China
| | - You Zhang
- 2 Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Lei Ren
- 2 Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Renqi Gao
- 2 Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Fang-Fang Yin
- 2 Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Hong Ge
- 1 Department of Radiation Oncology, Henan Cancer Hospital, The Affiliated Cancer Hospital of Zhengzhou University, Henan, China
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Dosimetric verification and quality assurance for intensity-modulated radiation therapy using Gafchromic® EBT3 film. JOURNAL OF RADIOTHERAPY IN PRACTICE 2017. [DOI: 10.1017/s1460396917000437] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractPurposeThis study aimed to examine the dosimetric properties of Gafchromic® EBT3 film and intensity-modulated radiation therapy quality assurance (IMRT QA).Materials and methodsBeams characteristics dosimetric properties and 20 IMRT plans were created and irradiated on Varian dual-energy DHX-S Linac for 6 and 15 MV energies. EBT3 films were analysed using ‘film Pro QA 2014’ software.ResultsThe dosimetric comparison of EBT3 film (for red channel dosimetry) and ionisation ion chamber measurement showed that average deviations of symmetry, flatness, central axis, penumbra (left) and penumbra (right) of dose profile were 0·18, 1·34, 0·49%, 3·68 and 3·61 mm for 6 MV and 0·10, 1·3, 0·45, 2·65 and 2·71 mm for 15 MV, respectively. The blue and green channels dosimetry showed greater dose deviation as compared with red channel. IMRT QA verification plan complied about 95% at all different criteria. Reproducibility, stability and face orientation of film were within 1·4% for red channel.ConclusionsThe results advocate that the film can be used not only for dosimetric assessment but also as a reliable IMRT QA tool.
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Giordanengo S, Manganaro L, Vignati A. Review of technologies and procedures of clinical dosimetry for scanned ion beam radiotherapy. Phys Med 2017; 43:79-99. [DOI: 10.1016/j.ejmp.2017.10.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 09/23/2017] [Accepted: 10/18/2017] [Indexed: 12/17/2022] Open
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Measurement of the influence of titanium hip prosthesis on therapeutic electron beam dose distributions in a novel pelvic phantom. Phys Med 2017; 42:99-107. [DOI: 10.1016/j.ejmp.2017.09.118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 08/24/2017] [Accepted: 09/07/2017] [Indexed: 11/17/2022] Open
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Differential dose absorptions for various biological tissue equivalent materials using Gafchromic XR-QA2 film in diagnostic radiology. Appl Radiat Isot 2017; 129:130-134. [PMID: 28843699 DOI: 10.1016/j.apradiso.2017.08.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/07/2017] [Accepted: 08/17/2017] [Indexed: 11/21/2022]
Abstract
Phantoms are devices that simulate human tissues including soft tissues, lungs, and bones in medical and health physics. The purpose of this work was to investigate the differential dose absorption in several commercially available low-cost materials as substitutes to human tissues using Gafchromic XR-QA2 film. The measurement of absorbed dose by different materials of various densities was made using the film to establish the relationship between the absorbed dose and the material density. Materials investigated included soft board materials, Perspex, chicken bone, Jeltrate, chalk, cow bone, marble, and aluminum, which have varying densities from 0.26 to 2.67gcm-3. The absorbed dose increased as the density and atomic number of the material increased. The absorbed dose to the density can be well represented by a polynomial function for the materials used.
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Archibald-Heeren BR, Byrne MV, Hu Y, Cai M, Wang Y. Robust optimization of VMAT for lung cancer: Dosimetric implications of motion compensation techniques. J Appl Clin Med Phys 2017; 18:104-116. [PMID: 28786213 PMCID: PMC5874938 DOI: 10.1002/acm2.12142] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 12/25/2022] Open
Abstract
In inverse planning of lung radiotherapy, techniques are required to ensure dose coverage of target disease in the presence of tumor motion as a result of respiration. A range of published techniques for mitigating motion effects were compared for dose stability across 5 breath cycles of ±2 cm. Techniques included planning target volume (PTV) expansions, internal target volumes with (OITV) and without tissue override (ITV), average dataset scans (ADS), and mini-max robust optimization. Volumetric arc therapy plans were created on a thorax phantom and verified with chamber and film measurements. Dose stability was compared by DVH analysis in calculations across all geometries. The lung override technique resulted in a substantial lack of dose coverage (-10%) to the tumor in the presence of large motion. PTV, ITV and ADS techniques resulted in substantial (up to 25%) maximum dose increases where solid tissue travelled into low density optimized regions. The results highlight the need for care in optimization of highly heterogeneous where density variations may occur with motion. Robust optimization was shown to provide greater stability in both maximum (<3%) and minimum dose variations (<2%) over all other techniques.
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Affiliation(s)
- Ben R Archibald-Heeren
- Radiation Oncology Centre, Sydney Adventist Hospital, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Mikel V Byrne
- Radiation Oncology Centre, Sydney Adventist Hospital, Sydney, NSW, Australia
| | - Yunfei Hu
- Radiation Oncology Centre, Sydney Adventist Hospital, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Meng Cai
- Radiation Oncology Centre, Sydney Adventist Hospital, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Yang Wang
- Radiation Oncology Centre, Sydney Adventist Hospital, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
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Hubley E, Briscoe M, Ploquin N, Pierce G. Technical Note: A novel quality assurance test to identify gantry angle inaccuracies in respiratory-gated VMAT treatments. Med Phys 2017; 44:5075-5080. [PMID: 28777468 DOI: 10.1002/mp.12499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/19/2017] [Accepted: 07/25/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE During respiratory-gated volumetric-modulated arc therapy (VMAT), the radiation beam is turned off each time the target exits the gating window. At the same time, the gantry slows, stops, and rewinds before the beam is turned back on. A quality assurance (QA) test was developed to detect inaccuracies in the gantry angle position between beam-off and beam-on events during respiratory-gated VMAT. METHODS Strips of Gafchromic™ EBT3 film were taped to the surface of a Capthan® 504 phantom mounted at isocenter. A homogeneous dose was delivered to the films through a 2 cm × 10 cm slit in the jaws using a respiratory-gated VMAT arc without the multileaf collimator. A periodic breathing cycle was used. Errors in gated delivery ranging from 0.5 to 5° were simulated by delivering nongated arcs with the same field size with over- and underlapping sections of 0.5-5°. The simulated errors were used to define QA levels to analyze the gated delivery. RESULTS The QA test was capable of detecting errors as small as 0.5°. The test was delivered to three Varian TrueBeam™ linacs, and no gantry angle inaccuracies greater than or equal to 0.5° were detected on any of the films. CONCLUSIONS A QA test capable of detecting gantry angle inaccuracies at beam-off and subsequent beam-on as small as 0.5° was developed and implemented for Varian TrueBeam™ linacs.
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Affiliation(s)
- Emily Hubley
- Department of Medical Physics, Tom Baker Cancer Centre, 1331 29 Street NW, Calgary, Alberta, T2N 4N2, Canada
| | - Michael Briscoe
- Department of Medical Physics, Tom Baker Cancer Centre, 1331 29 Street NW, Calgary, Alberta, T2N 4N2, Canada
| | - Nicolas Ploquin
- Department of Medical Physics, Tom Baker Cancer Centre, 1331 29 Street NW, Calgary, Alberta, T2N 4N2, Canada.,Department of Physics & Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.,Department of Oncology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada
| | - Greg Pierce
- Department of Medical Physics, Tom Baker Cancer Centre, 1331 29 Street NW, Calgary, Alberta, T2N 4N2, Canada.,Department of Physics & Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.,Department of Oncology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada
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38
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Li Y, Chen L, Zhu J, Liu X. The combination of the error correction methods of GAFCHROMIC EBT3 film. PLoS One 2017; 12:e0181958. [PMID: 28750023 PMCID: PMC5531657 DOI: 10.1371/journal.pone.0181958] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 07/10/2017] [Indexed: 11/18/2022] Open
Abstract
Purpose The aim of this study was to combine a set of methods for use of radiochromic film dosimetry, including calibration, correction for lateral effects and a proposed triple-channel analysis. These methods can be applied to GAFCHROMIC EBT3 film dosimetry for radiation field analysis and verification of IMRT plans. Methods A single-film exposure was used to achieve dose calibration, and the accuracy was verified based on comparisons with the square-field calibration method. Before performing the dose analysis, the lateral effects on pixel values were corrected. The position dependence of the lateral effect was fitted by a parabolic function, and the curvature factors of different dose levels were obtained using a quadratic formula. After lateral effect correction, a triple-channel analysis was used to reduce disturbances and convert scanned images from films into dose maps. The dose profiles of open fields were measured using EBT3 films and compared with the data obtained using an ionization chamber. Eighteen IMRT plans with different field sizes were measured and verified with EBT3 films, applying our methods, and compared to TPS dose maps, to check correct implementation of film dosimetry proposed here. Results The uncertainty of lateral effects can be reduced to ±1 cGy. Compared with the results of Micke A et al., the residual disturbances of the proposed triple-channel method at 48, 176 and 415 cGy are 5.3%, 20.9% and 31.4% smaller, respectively. Compared with the ionization chamber results, the difference in the off-axis ratio and percentage depth dose are within 1% and 2%, respectively. For the application of IMRT verification, there were no difference between two triple-channel methods. Compared with only corrected by triple-channel method, the IMRT results of the combined method (include lateral effect correction and our present triple-channel method) show a 2% improvement for large IMRT fields with the criteria 3%/3 mm.
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Affiliation(s)
- Yinghui Li
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
| | - Lixin Chen
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People’s Republic of China
| | - Jinhan Zhu
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People’s Republic of China
| | - Xiaowei Liu
- School of Physics, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
- * E-mail:
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39
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Ade N, du Plessis FCP. Dose comparison between Gafchromic film, XiO, and Monaco treatment planning systems in a novel pelvic phantom that contains a titanium hip prosthesis. J Appl Clin Med Phys 2017; 18:162-173. [PMID: 28741892 PMCID: PMC5874810 DOI: 10.1002/acm2.12141] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 06/05/2017] [Accepted: 06/09/2017] [Indexed: 11/29/2022] Open
Abstract
The presence of metallic prostheses during external beam radiotherapy of malignancies in the pelvic region has the potential to strongly influence the dose distribution to the target and to tissue surrounded by the prostheses. This study systematically investigates the perturbation effects of unilateral titanium prosthesis on 6 and 15 MV photon beam dose distributions using Gafchromic EBT2 film measurements in a novel pelvic phantom made out of a stack of nylon slices. Comparisons were also made between the film data and dose calculations made on XiO and Monaco treatment planning systems. The collapsed cone algorithm was chosen for the XiO and the Monte Carlo algorithm used on Monaco is XVMC. Transmission measurements were taken using a narrow‐beam geometry to determine the mass attenuation coefficient of nylon = 0.0458 cm2/g and for a water‐equivalent RW3 phantom, it was 0.0465 cm2/g. The perturbation effects of the prosthesis on dose distributions were investigated by measuring and comparing dose maps and profiles. The magnitude of dose perturbations was quantified by calculating dose enhancement and reduction factors using field sizes of 3 × 3, 5 × 5, 10 × 10, and 15 × 15 cm2. For the studied beams and field sizes, dose enhancements between 21 and 30% and dose reductions between 15 and 21% were observed at the nylon‐prosthesis interface on the proximal and distal sides of the prosthesis for film measurements. The dose escalation increases with beam energy, and the dose reduction due to attenuation decreases with increasing beam energy when compared to unattenuated beam data. A comparison of film and XiO depth doses for the studied fields gave relative errors between 1.1 and 23.2% at the proximal and distal interfaces of the Ti prosthesis. Also, relative errors < 4.0% were obtained between film and Monaco dose data outside the prosthesis for 6 and 15 MV lateral opposing fields.
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Affiliation(s)
- Nicholas Ade
- Medical Physics Department, University of the Free State, Bloemfontein, South Africa
| | - F C P du Plessis
- Medical Physics Department, University of the Free State, Bloemfontein, South Africa
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40
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Callens MB, Crijns W, Depuydt T, Haustermans K, Maes F, D’Agostino E, Wevers M, Pfeiffer H, Van Den Abeele K. Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films. Med Phys 2017; 44:2532-2543. [DOI: 10.1002/mp.12246] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 02/16/2017] [Accepted: 03/14/2017] [Indexed: 11/10/2022] Open
Affiliation(s)
- Maarten B. Callens
- Wave Propagation and Signal Processing; KU Leuven - KULAK; Kortrijk 8500 Belgium
| | - Wouter Crijns
- Department of Radiation Oncology; University Hospitals Leuven; Leuven 3000 Belgium
| | - Tom Depuydt
- Department of Radiation Oncology; University Hospitals Leuven; Leuven 3000 Belgium
| | - Karin Haustermans
- Department of Radiation Oncology; University Hospitals Leuven; Leuven 3000 Belgium
| | - Frederik Maes
- Department of Electrical Engineering; ESAT/PSI, KU Leuven; Leuven 3001 Belgium
| | | | - Martine Wevers
- Department of Materials Engineering; KU Leuven; Leuven 3001 Belgium
| | - Helge Pfeiffer
- Department of Materials Engineering; KU Leuven; Leuven 3001 Belgium
| | - Koen Van Den Abeele
- Wave Propagation and Signal Processing; KU Leuven - KULAK; Kortrijk 8500 Belgium
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41
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Hsiao MC, Jiang SH. A Characterization Study of GafChromic EBT Film as a Two-Dimensional Dosimeter. NUCL TECHNOL 2017. [DOI: 10.13182/nt09-a9124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Ming-Chen Hsiao
- National Tsing Hua University, Department of Engineering and System Science 101, Sec. 2, Kung-Fu Road, Hsinchu, Taiwan 30013
| | - Shiang-Huei Jiang
- National Tsing Hua University, Department of Engineering and System Science 101, Sec. 2, Kung-Fu Road, Hsinchu, Taiwan 30013
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43
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Borowicz DM, Malicki J, Mytsin G, Shipulin K. Dose distribution at the Bragg peak: Dose measurements using EBT and RTQA gafchromic film set at two positions to the central beam axis. Med Phys 2017; 44:1538-1544. [PMID: 28196271 DOI: 10.1002/mp.12159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 01/23/2017] [Accepted: 02/05/2017] [Indexed: 11/08/2022] Open
Abstract
AIM To evaluate the impact of radiochromic film positioning relative to the central beam axis (CAX) in proton beam therapy. Secondarily, to compare the dosimetric measurements obtained by RTQA and EBT film and to compare these to the doses calculated by the treatment planning system (TPS). METHODS The EBT and RTQA dosimetric radiochromic films were immersed in a water phantom and irradiated with a proton beam. The films were placed parallel to the CAX and at a 5° angle on the horizontal plane to assess the effect of film inclination on Bragg peak profiles. Calibration was performed by irradiating small pieces of film at doses ranging from 0.0 Gy to 3.5 Gy in increments of 0.5 Gy. The TPS was used to create treatment plans for two different geometrical targets (cylindrical and cuboidal). After irradiation, all film pieces were scanned on a flatbed scanner and red channel data were extracted from the 48-bit RGB images using ImageJ, Photoshop, Origin8, and Excel software. The dose distributions from the irradiated films were compared to the dose obtained from the TPS. Bragg peak profiles were abstracted from the irradiated films and compared. RESULTS The dosimetric measurements obtained by both EBT and RTQA positioned at a 5° to the CAX closely matched the dose calculated by the TPS for the cylindrical target. In contrast, dose distributions measured in the cuboidal targets were less precise. Gamma index (GI) values (3%/3 mm acceptance criteria for isodose >90% of dose) were 99.8% and 93% for EBT film placed at a 5° angle versus 47.1% and 80.8% for EBT film parallel to the beam. The dosimetric measurements in RTQA film positioned parallel to the CAX showed GI values with <27% agreement with the TPS-calculated dose. CONCLUSION Our finding show that RTQA film can be used to accurately measure doses in the proton beam at the region of Bragg peak; however, to obtain the most accurate readings, the film should be positioned at a small angle to the CAX.
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Affiliation(s)
- Dorota Maria Borowicz
- Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland.,Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
| | - Julian Malicki
- Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland.,Electroradiology Department, University of Medical Sciences, Poznan, Poland
| | - Gennady Mytsin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
| | - Konstantin Shipulin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
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44
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Cusumano D, Fumagalli ML, Ghielmetti F, Rossi L, Grossi G, Lanzarotti R, Fariselli L, De Martin E. Sum signal dosimetry: A new approach for high dose quality assurance with Gafchromic EBT3. J Appl Clin Med Phys 2017; 18:181-190. [PMID: 28300373 PMCID: PMC5689947 DOI: 10.1002/acm2.12045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 11/17/2016] [Accepted: 11/24/2016] [Indexed: 11/23/2022] Open
Abstract
Gafchromic EBT3 film dosimetry in radiosurgery (RS) and hypofractionated radiotherapy (HRT) is complicated by the limited film accuracy at high fractional doses. The aim of this study is to develop and evaluate sum signal (SS) film dosimetry to increase dose resolution at high fractional doses, thus allowing for use of EBT3 for dose distribution verification of RS/HRT treatments. To characterize EBT3 dose–response, a calibration was performed in the dose range 0.44–26.43 Gy. Red (RC) and green (GC) channel net optical densities were linearly added to produce the SS. Dose resolution and overall accuracy of the dosimetric protocol were estimated and compared for SS,RC, and GC. A homemade Matlab software was developed to compare, in terms of gamma analysis, dose distributions delivered by a Cyberknife on EBT3 films to dose distributions calculated by the treatment planning system. The new SS and conventional single channel (SC) methods were compared, using 3%/1 and 4%/1 mm acceptance criteria, for 20 patient plans. Our analysis shows that the SS dose–response curve is characterized by a steeper trend in comparison with SC, with SS providing a higher dose resolution in the whole dose range investigated. Gamma analysis confirms that the percentage of points satisfying the agreement criteria is significantly higher for SS compared to SC: 95.03% vs. 88.41% (P = 0.014) for 3%/1 mm acceptance criteria and 97.24% vs. 93.58% (P = 0.048) for 4%/1 mm acceptance criteria. This study demonstrates that the SS approach is a new and effective method to improve dosimetric accuracy in the framework of the RS‐HRT patient‐specific quality assurance protocol.
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Affiliation(s)
- Davide Cusumano
- School of Medical Physics, University of Milan, 20133, Milan, Italy
| | - Maria Luisa Fumagalli
- Health Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Francesco Ghielmetti
- Health Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Linda Rossi
- School of Medical Physics, University of Milan, 20133, Milan, Italy
| | - Giuliano Grossi
- Department of Computer Science, University of Milan, 20135, Milan, Italy
| | | | - Laura Fariselli
- Department of Neurosurgery, Radiotherapy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Elena De Martin
- Health Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
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Kawashima M, Kawamura H, Onishi M, Takakusagi Y, Okonogi N, Okazaki A, Sekihara T, Ando Y, Nakano T. The Impact of the Grid Size on TomoTherapy for Prostate Cancer. J Med Phys 2017; 42:144-150. [PMID: 28974860 PMCID: PMC5618461 DOI: 10.4103/jmp.jmp_123_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Discretization errors due to the digitization of computed tomography images and the calculation grid are a significant issue in radiation therapy. Such errors have been quantitatively reported for a fixed multifield intensity-modulated radiation therapy using traditional linear accelerators. The aim of this study is to quantify the influence of the calculation grid size on the dose distribution in TomoTherapy. This study used ten treatment plans for prostate cancer. The final dose calculation was performed with "fine" (2.73 mm) and "normal" (5.46 mm) grid sizes. The dose distributions were compared from different points of view: the dose-volume histogram (DVH) parameters for planning target volume (PTV) and organ at risk (OAR), the various indices, and dose differences. The DVH parameters were used Dmax, D2%, D2cc, Dmean, D95%, D98%, and Dmin for PTV and Dmax, D2%, and D2cc for OARs. The various indices used were homogeneity index and equivalent uniform dose for plan evaluation. Almost all of DVH parameters for the "fine" calculations tended to be higher than those for the "normal" calculations. The largest difference of DVH parameters for PTV was Dmax and that for OARs was rectal D2cc. The mean difference of Dmax was 3.5%, and the rectal D2cc was increased up to 6% at the maximum and 2.9% on average. The mean difference of D95% for PTV was the smallest among the differences of the other DVH parameters. For each index, whether there was a significant difference between the two grid sizes was determined through a paired t-test. There were significant differences for most of the indices. The dose difference between the "fine" and "normal" calculations was evaluated. Some points around high-dose regions had differences exceeding 5% of the prescription dose. The influence of the calculation grid size in TomoTherapy is smaller than traditional linear accelerators. However, there was a significant difference. We recommend calculating the final dose using the "fine" grid size.
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Affiliation(s)
| | - Hidemasa Kawamura
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masahiro Onishi
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | | | - Noriyuki Okonogi
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan.,Hospital, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan
| | | | | | | | - Takashi Nakano
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan
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Castriconi R, Ciocca M, Mirandola A, Sini C, Broggi S, Schwarz M, Fracchiolla F, Martišíková M, Aricò G, Mettivier G, Russo P. Dose–response of EBT3 radiochromic films to proton and carbon ion clinical beams. Phys Med Biol 2016; 62:377-393. [DOI: 10.1088/1361-6560/aa5078] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Characterization of stochastic noise and post-irradiation density growth for reflective-type radiochromic film in therapeutic photon beam dosimetry. Phys Med 2016; 32:1314-1320. [PMID: 27473441 DOI: 10.1016/j.ejmp.2016.07.091] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 07/15/2016] [Accepted: 07/17/2016] [Indexed: 11/23/2022] Open
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Marroquin EYL, Herrera González JA, Camacho López MA, Barajas JEV, García-Garduño OA. Evaluation of the uncertainty in an EBT3 film dosimetry system utilizing net optical density. J Appl Clin Med Phys 2016; 17:466-481. [PMID: 27685125 PMCID: PMC5874103 DOI: 10.1120/jacmp.v17i5.6262] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 05/19/2016] [Accepted: 05/16/2016] [Indexed: 11/23/2022] Open
Abstract
Radiochromic film has become an important tool to verify dose distributions for intensity-modulated radiotherapy (IMRT) and quality assurance (QA) procedures. A new radiochromic film model, EBT3, has recently become available, whose composition and thickness of the sensitive layer are the same as those of previous EBT2 films. However, a matte polyester layer was added to EBT3 to prevent the formation of Newton's rings. Furthermore, the symmetrical design of EBT3 allows the user to eliminate side-orientation dependence. This film and the flatbed scanner, Epson Perfection V750, form a dosimetry system whose intrinsic characteristics were studied in this work. In addition, uncertainties associated with these intrinsic characteristics and the total uncertainty of the dosimetry system were determined. The analysis of the response of the radiochromic film (net optical density) and the fitting of the experimental data to a potential function yielded an uncertainty of 2.6%, 4.3%, and 4.1% for the red, green, and blue channels, respectively. In this work, the dosimetry system presents an uncertainty in resolving the dose of 1.8% for doses greater than 0.8 Gy and less than 6 Gy for red channel. The films irradiated between 0 and 120 Gy show differences in the response when scanned in portrait or landscape mode; less uncertainty was found when using the portrait mode. The response of the film depended on the position on the bed of the scanner, contributing an uncertainty of 2% for the red, 3% for the green, and 4.5% for the blue when placing the film around the center of the bed of scanner. Furthermore, the uniformity and reproducibility radiochromic film and reproducibility of the response of the scanner contribute less than 1% to the overall uncertainty in dose. Finally, the total dose uncertainty was 3.2%, 4.9%, and 5.2% for red, green, and blue channels, respectively. The above uncertainty values were obtained by mini-mizing the contribution to the total dose uncertainty of the film orientation and film homogeneity.
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Mastella E, Vigorito S, Rondi E, Piperno G, Ferrari A, Strata E, Rozza D, Jereczek-Fossa BA, Cattani F. Validation of a pretreatment delivery quality assurance method for the CyberKnife Synchrony system. Med Phys 2016; 43:4565. [DOI: 10.1118/1.4955437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Chang L, Ho SY, Lee TF, Yeh SA, Ding HJ, Chen PY. Calibration of EBT2 film using a red-channel PDD method in combination with a modified three-channel technique. Med Phys 2016; 42:5838-47. [PMID: 26429258 DOI: 10.1118/1.4930253] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Ashland Inc. EBT2 and EBT3 films are widely used in quality assurance for radiation therapy; however, there remains a relatively high degree of uncertainty [B. Hartmann, M. Martisikova, and O. Jakel, "Homogeneity of Gafchromic EBT2 film," Med. Phys. 37, 1753-1756 (2010)]. Micke et al. (2011) recently improved the spatial homogeneity using all color channels of a flatbed scanner; however, van Hoof et al. (2012) pointed out that the corrected nonuniformity still requires further investigation for larger fields. To reduce the calibration errors and the uncertainty, the authors propose a new red-channel percentage-depth-dose method in combination with a modified three-channel technique. METHODS For the ease of comparison, the EBT2 film image used in the authors' previous study (2012) was reanalyzed using different approaches. Photon beams of 6-MV were delivered to two different films at two different beam on times, resulting in the absorption doses of ranging from approximately 30 to 300 cGy at the vertical midline of the film, which was set to be coincident with the central axis of the beam. The film was tightly sandwiched in a 30(3)-cm(3) polystyrene phantom, and the pixel values for red, green, and blue channels were extracted from 234 points on the central axis of the beam and compared with the corresponding depth doses. The film was first calibrated using the multichannel method proposed by Micke et al. (2010), accounting for nonuniformities in the scanner. After eliminating the scanner and dose-independent nonuniformities, the film was recalibrated via the dose-dependent optical density of the red channel and fitted to a power function. This calibration was verified via comparisons of the dose profiles extracted from the films, where three were exposed to a 60° physical wedge field and three were exposed to composite fields, and all of which were measured in a water phantom. A correction for optical attenuation was implemented, and treatment plans of intensity modulated radiation therapy and volumetric modulated arc therapy were evaluated. RESULTS The method described here demonstrated improved accuracy with reduced uncertainty. The relative error compared with the measurements of a water phantom was less than 1%, and the overall calibration uncertainty was less than 2%. Verification tests revealed that the results were close to those of the authors' previous study, and all differences were within 3%, except those with a high-dose gradient. The gamma pass rates (2%/2 mm) of the treatment plan evaluated using the method described here were greater than 99%, and no obvious stripe patterns were observed in the dose-difference maps. CONCLUSIONS Spatial homogeneity was significantly improved via the calibration method described here. This technique is both convenient and time-efficient because it does not require cutting the film, and only two exposures are necessary.
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Affiliation(s)
- Liyun Chang
- Departments of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung 82445, Taiwan
| | - Sheng-Yow Ho
- Department of Nursing, Chang Jung Christian University, Tainan 73657, Taiwan and Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan 73657, Taiwan
| | - Tsair-Fwu Lee
- Medical Physics and Informatics Laboratory, Department of Electronics Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan
| | - Shyh-An Yeh
- Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung 82445, Taiwan and Department of Radiation Oncology, E-Da Hospital, Kaohsiung 82445, Taiwan
| | - Hueisch-Jy Ding
- Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung 82445, Taiwan
| | - Pang-Yu Chen
- Department of Radiation Oncology, Sinlau Christian Hospital, Tainan 70142, Taiwan
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