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Maeyama T, Hayashi K, Watanabe Y, Ohara M, Nakagawa S. Development of a silicone-based radio-fluorogenic dosimeter using dihydrorhodamine 6G. Phys Med 2023; 114:102684. [PMID: 37778206 DOI: 10.1016/j.ejmp.2023.102684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/24/2023] [Accepted: 09/11/2023] [Indexed: 10/03/2023] Open
Abstract
A silicon-based three-dimensional dosimeter can be formed in a free shape without a container and deformed because of its flexibility. Several studies have focused on enhancing its radiological characteristics and assessing its applicability as a quality assurance tool for image-guided and adaptive radiation therapy, considering motion and deformation. Here, we applied a fluorescence probe (dihydrorhodamine 6G, DHR6G) to a silicon elastomer as a new radiosensitive compound that converts nonfluorescent into fluorescent dyes using irradiation, and its fluorescence intensity increases linearly with the absorbed dose. In this study, we demonstrated a cost-effective synthesis method and optimized the composition conditions. The results showed that the DHR6G-SE prepared from 2.2 × 10-3 wt% DHR6G, 0.024 wt% pyridine, and a silicone elastomer (SE) (SILPOT TM 184, base/curing agent = 10/1) exhibited a linear increase in fluorescence with radiation exposure within a dose range of 0-8 Gy and a highly stable sensitivity for as long as 64 h. To demonstrate its container-less characteristics, the possibility of dosimetry for low-energy X-rays using DHR6G-SE was investigated.
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Affiliation(s)
- Takuya Maeyama
- Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252-0373, Japan; RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Kiichiro Hayashi
- Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252-0373, Japan
| | - Yusuke Watanabe
- School of Allied Health Sciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Maki Ohara
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-City, Chiba 263-8555, Japan
| | - Seiko Nakagawa
- Tokyo Metropolitan Industrial Technology Research Institute, 2-4-10 Aomi, Koto-ku, Tokyo 135-0064, Japan
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Lozares-Cordero S, Bermejo-Barbanoj C, Badías-Herbera A, Ibáñez-Carreras R, Ligorred-Padilla L, Ponce-Ortega JM, González-Pérez V, Gandía-Martínez A, Font-Gómez JA, Blas-Borroy O, González-Ibáñez D. An open-source development based on photogrammetry for a real-time IORT treatment planning system. Phys Med 2023; 112:102622. [PMID: 37331081 DOI: 10.1016/j.ejmp.2023.102622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/20/2023] Open
Abstract
PURPOSE This study presents a treatment planning system for intraoperative low-energy photon radiotherapy based on photogrammetry from real images of the surgical site taken in the operating room. MATERIAL AND METHODS The study population comprised 15 patients with soft-tissue sarcoma. The system obtains the images of the area to be irradiated with a smartphone or tablet, so that the absorbed doses in the tissue can be calculated from the reconstruction without the need for computed tomography. The system was commissioned using 3D printing of the reconstructions of the tumor beds. The absorbed doses at various points were verified using radiochromic films that were suitably calibrated for the corresponding energy and beam quality. RESULTS The average reconstruction time of the 3D model from the video sequence in the 15 patients was 229,6±7,0 s. The entire procedure, including video capture, reconstruction, planning, and dose calculation was 520,6±39,9 s. Absorbed doses were measured on the 3D printed model with radiochromic film, the differences between these measurements and those calculated by the treatment planning system were 1.4% at the applicator surface, 2.6% at 1 cm, 3.9% at 2 cm and 6.2% at 3 cm. CONCLUSIONS The study shows a photogrammetry-based low-energy photon IORT planning system, capable of obtaining real-time images inside the operating room, immediately after removal of the tumor and immediately before irradiation. The system was commissioned with radiochromic films measurements in 3D-printed model.
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Affiliation(s)
- Sergio Lozares-Cordero
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain.
| | | | - Alberto Badías-Herbera
- Higher Technical School of Industrial Engineering, Polytechnic University of Madrid, Spain
| | | | - Luis Ligorred-Padilla
- Esophagogastric Surgery and Sarcoma Unit (Department of General and Gastrointestinal Surgery), Miguel Servet University Hospital, Zaragoza, Spain
| | | | | | | | - José Antonio Font-Gómez
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain
| | - Olga Blas-Borroy
- Engineering and Maintenance Service, Miguel Servet University Hospital, Zaragoza, Spain
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Huang L, Gaballa H, Chang J. Evaluating dosimetric accuracy of the 6 MV calibration on EBT3 film in the use of Ir-192 high dose rate brachytherapy. J Appl Clin Med Phys 2022; 23:e13571. [PMID: 35226398 PMCID: PMC9121041 DOI: 10.1002/acm2.13571] [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: 09/23/2021] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 12/03/2022] Open
Abstract
Purpose To evaluate the dosimetric accuracy of EBT3 film calibrated with a 6 MV beam for high dose rate brachytherapy and propose a novel method for direct film calibration with an Ir‐192 source. Methods The 6 MV calibration was performed in water on a linear accelerator (linac). The Ir‐192 calibration was accomplished by irradiating the film wrapped around a cylinder applicator with an Ir‐192 source. All films were scanned 1‐day post‐irradiation to acquire calibration curves for all three (red, blue, and green) channels. The Ir‐192 calibration films were also used for single‐dose comparison. Moreover, an independent test film under a H.A.M. applicator was irradiated and the 2D dose distribution was obtained separately for each calibration using the red channel data. Gamma analysis and point‐by‐point profile comparison were performed to evaluate the performance of both calibrations. The uncertainty budget for each calibration system was analyzed. Results The red channel had the best performance for both calibration systems in the single‐dose comparison. We found a significant 4.89% difference from the reference for doses <250 cGy using the 6 MV calibration, while the difference was only 0.87% for doses >600 cGy. Gamma analysis of the 2D dose distribution showed the Ir‐192 calibration had a higher passing rate of 91.9% for the 1 mm/2% criterion, compared to 83.5% for the 6 MV calibration. Most failing points were in the low‐dose region (<200 cGy). The point‐by‐point profile comparison reported a discrepancy of 2%–3.6% between the Ir‐192 and 6 MV calibrations in this low‐dose region. The linac‐ and Ir‐192‐based dosimetry systems had an uncertainty of 4.1% (k = 2) and 5.66% (k = 2), respectively. Conclusions Direct calibration of EBT3 films with an Ir‐192 source is feasible and reliable, while the dosimetric accuracy of 6 MV calibration depends on the dose range. The Ir‐192 calibration should be used when the measurement dose range is below 250 cGy.
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Affiliation(s)
- Lyu Huang
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA
| | - Hani Gaballa
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA
| | - Jenghwa Chang
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA.,Department of Radiation Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, New Hyde Park, New York, USA.,Department of Physics and Astronomy, Hofstra University, Hempstead, New York, USA
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4
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Méndez I, Rovira-Escutia JJ, Casar B. A protocol for accurate radiochromic film dosimetry using Radiochromic.com. Radiol Oncol 2021; 55:369-378. [PMID: 34384012 PMCID: PMC8366735 DOI: 10.2478/raon-2021-0034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Radiochromic films have many applications in radiology and radiation therapy. Generally, the dosimetry system for radiochromic film dosimetry is composed of radiochromic films, flatbed scanner, and film analysis software. The purpose of this work is to present the effectiveness of a protocol for accurate radiochromic film dosimetry using Radiochromic.com as software for film analysis. MATERIALS AND METHODS Procedures for image acquisition, lot calibration, and dose calculation are explained and analyzed. Radiochromic.com enables state-of-the-art models and corrections for radiochromic film dosimetry, such as the Multigaussian model for multichannel film dosimetry, and lateral, inter-scan, and re-calibration corrections of the response. RESULTS The protocol presented here provides accurate dose results by mitigating the sources of uncertainty that affect radiochromic film dosimetry. CONCLUSIONS Appropriate procedures for film and scanner handling in combination with Radiochromic.com as software for film analysis make easy and accurate radiochromic film dosimetry feasible.
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Affiliation(s)
- Ignasi Méndez
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
| | | | - Bozidar Casar
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
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Sharma M, Singh R, Robert N, Trivedi G, Tomar P, Oinam A. Beam quality and dose rate dependency of Gafchromic EBT3 film irradiated with therapeutic megavolt photon beams. RADIAT MEAS 2021. [DOI: 10.1016/j.radmeas.2021.106632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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6
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Lozares S, Font JA, Gandía A, Campos A, Flamarique S, Ibáñez R, Villa D, Alba V, Jiménez S, Hernández M, Casamayor C, Vicente I, Hernando E, Rubio P. In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film. Phys Med 2021; 81:173-181. [PMID: 33465753 DOI: 10.1016/j.ejmp.2020.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.
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Affiliation(s)
- Sergio Lozares
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain.
| | - Jose A Font
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Almudena Gandía
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Arantxa Campos
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sonia Flamarique
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Reyes Ibáñez
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - David Villa
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Verónica Alba
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sara Jiménez
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Mónica Hernández
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Carmen Casamayor
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Isabel Vicente
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Ernesto Hernando
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Patricia Rubio
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
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7
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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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Massillon-Jl G, Cabrera-Santiago A, Xicohténcatl-Hernández N. Relative efficiency of Gafchromic EBT3 and MD-V3 films exposed to low-energy photons and its influence on the energy dependence. Phys Med 2019; 61:8-17. [PMID: 31151584 DOI: 10.1016/j.ejmp.2019.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 11/17/2022] Open
Abstract
Energy-dependence of Gafchromic films exposed to low-energy photons has been reported to be a function of absorbed-dose. However, these studies are based on a relative-response, R, which considers the absorbed-dose in water and not within the film sensitive-volume. This work investigated the relative-efficiency, REfilm, (ratio of absorbed-dose required to produce the same net optical density (netOD) by 60Co gamma and by x-ray) of Gafchromic EBT3 and MD-V3 films exposed to five x-ray beams from 20 kV to 160 kV and 60Co gamma rays. A factor that accounts for the energy-dependence, fx,Q,med, based on REfilm, phantom-material and depth at which the films are placed during irradiation was used to remove the influence of absorbed dose. Values of REfilm indicated that the absorbed dose from 60Co gamma rays needs to be 4 and 3 times larger than those from 20 kV x-rays to produce the same netOD within the EBT3 and MD-V3 sensitive volumes, respectively. Thus, saturation could help explain why Gafchromic films show under-response to very low doses from low-energy photon beams, regardless of film model. Furthermore, REfilm, was found to be nearly independent of netOD and colour-channels. Consequently, fx,Q,med is independent of the absorbed dose and colour-channels. In contrast, besides the variation with the photon energy, fx,Q,med varied with film model, depth and phantom material used during the irradiation. Thus, the results suggest that fx,Q,med is a more reliable wide-ranging parameter for evaluating the degree of energy-dependence of the film rather than the relative-response method commonly considered.
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Affiliation(s)
- Guerda Massillon-Jl
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan, Mexico City, Mexico.
| | - Alexis Cabrera-Santiago
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan, Mexico City, Mexico
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Méndez I, Polšak A, Hudej R, Casar B. The Multigaussian method: a new approach to mitigating spatial heterogeneities with multichannel radiochromic film dosimetry. Phys Med Biol 2018; 63:175013. [PMID: 30101754 DOI: 10.1088/1361-6560/aad9c1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The main objective of multichannel radiochromic film dosimetry methods is to correct, or at least mitigate, spatial heterogeneities in the film-scanner response, especially variations in the active layer thickness. To this end, films can also be scanned prior to irradiation. In this study, the abilities of various single channel and multichannel methods to reduce spatial heterogeneities, with and without scanning before irradiation, were tested. Red, green and blue single channel models, two additive channel independent perturbation (CHIP) models and two multiplicative CHIP models were compared with the Multigaussian method. The Multigaussian method is a new approach to multichannel dosimetry, based on experimental findings. It assumes that the probability density function of the response vector formed by the pixel values of the different color channels, including irradiated and non-irradiated scans, follows a multivariate Gaussian distribution. The Multigaussian method provided more accurate doses than the other models under comparison, especially when incorporating the information of the film prior to irradiation. The relative dose differences between reference doses measured with MatriXX and film doses were examined. After applying inter-scan and lateral corrections, the lowest mean absolute errors were 0.8% and 1.0% for the Multigaussian method with and without the information of the scan before irradiation, respectively. Followed by the uniform multiplicative CHIP and red single channel models, using pixel values and net optical density, respectively, both with 1.1%.
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Affiliation(s)
- I Méndez
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
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10
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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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Osman AF, Maalej N, Ul-Rahman K, Rahman WA. Heterogeneity and scatter effects on Ir-192 brachytherapy dose distribution. Phys Med 2016; 32:1210-1215. [DOI: 10.1016/j.ejmp.2016.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 07/24/2016] [Accepted: 09/06/2016] [Indexed: 10/21/2022] Open
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Film based verification of calculation algorithms used for brachytherapy planning-getting ready for upcoming challenges of MBDCA. J Contemp Brachytherapy 2016; 8:326-35. [PMID: 27648087 PMCID: PMC5018527 DOI: 10.5114/jcb.2016.61828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 07/29/2016] [Indexed: 11/17/2022] Open
Abstract
Purpose Well-known defect of TG-43 based algorithms used in brachytherapy is a lack of information about interaction cross-sections, which are determined not only by electron density but also by atomic number. TG-186 recommendations with using of MBDCA (model-based dose calculation algorithm), accurate tissues segmentation, and the structure's elemental composition continue to create difficulties in brachytherapy dosimetry. For the clinical use of new algorithms, it is necessary to introduce reliable and repeatable methods of treatment planning systems (TPS) verification. The aim of this study is the verification of calculation algorithm used in TPS for shielded vaginal applicators as well as developing verification procedures for current and further use, based on the film dosimetry method. Material and methods Calibration data was collected by separately irradiating 14 sheets of Gafchromic® EBT films with the doses from 0.25 Gy to 8.0 Gy using HDR 192Ir source. Standard vaginal cylinders of three diameters were used in the water phantom. Measurements were performed without any shields and with three shields combination. Gamma analyses were performed using the VeriSoft® package. Results Calibration curve was determined as third-degree polynomial type. For all used diameters of unshielded cylinder and for all shields combinations, Gamma analysis were performed and showed that over 90% of analyzed points meets Gamma criteria (3%, 3 mm). Conclusions Gamma analysis showed good agreement between dose distributions calculated using TPS and measured by Gafchromic films, thus showing the viability of using film dosimetry in brachytherapy.
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Laschinsky L, Karsch L, Leßmann E, Oppelt M, Pawelke J, Richter C, Schürer M, Beyreuther E. Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2016; 55:381-91. [PMID: 27193178 DOI: 10.1007/s00411-016-0652-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 05/09/2016] [Indexed: 05/25/2023]
Abstract
Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.
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Affiliation(s)
- Lydia Laschinsky
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany
- Menarini - Von Heyden GmbH, Leipziger Straße 7 - 13, 01097, Dresden, Germany
| | - Leonhard Karsch
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
| | - Elisabeth Leßmann
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany
| | - Melanie Oppelt
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany
- Quintiles GmbH, Hugenottenallee 167, 63263, Neu-Isenburg, Germany
| | - Jörg Pawelke
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany
| | - Christian Richter
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany
| | - Michael Schürer
- OncoRay - National Centre for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, PF 41, 01307, Dresden, Germany
| | - Elke Beyreuther
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Bautzner Landstraße 400, P.O. Box 510119, 01314, Dresden, Germany.
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14
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Massillon-JL G, Muñoz-Molina ID, Díaz-Aguirre P. Optimum absorbed dose versus energy response of Gafchromic EBT2 and EBT3 films exposed to 20–160 kV x-rays and
60
Co gamma. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/4/045005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Izewska J, Wesolowska P, Azangwe G, Followill DS, Thwaites DI, Arib M, Stefanic A, Viegas C, Suming L, Ekendahl D, Bulski W, Georg D. Testing the methodology for dosimetry audit of heterogeneity corrections and small MLC-shaped fields: Results of IAEA multi-center studies. Acta Oncol 2016; 55:909-16. [PMID: 26934916 PMCID: PMC4926790 DOI: 10.3109/0284186x.2016.1139180] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The International Atomic Energy Agency (IAEA) has a long tradition of supporting development of methodologies for national networks providing quality audits in radiotherapy. A series of co-ordinated research projects (CRPs) has been conducted by the IAEA since 1995 assisting national external audit groups developing national audit programs. The CRP ‘Development of Quality Audits for Radiotherapy Dosimetry for Complex Treatment Techniques’ was conducted in 2009–2012 as an extension of previously developed audit programs. Material and methods. The CRP work described in this paper focused on developing and testing two steps of dosimetry audit: verification of heterogeneity corrections, and treatment planning system (TPS) modeling of small MLC fields, which are important for the initial stages of complex radiation treatments, such as IMRT. The project involved development of a new solid slab phantom with heterogeneities containing special measurement inserts for thermoluminescent dosimeters (TLD) and radiochromic films. The phantom and the audit methodology has been developed at the IAEA and tested in multi-center studies involving the CRP participants. Results. The results of multi-center testing of methodology for two steps of dosimetry audit show that the design of audit procedures is adequate and the methodology is feasible for meeting the audit objectives. A total of 97% TLD results in heterogeneity situations obtained in the study were within 3% and all results within 5% agreement with the TPS predicted doses. In contrast, only 64% small beam profiles were within 3 mm agreement between the TPS calculated and film measured doses. Film dosimetry results have highlighted some limitations in TPS modeling of small beam profiles in the direction of MLC leave movements. Discussion. Through multi-center testing, any challenges or difficulties in the proposed audit methodology were identified, and the methodology improved. Using the experience of these studies, the participants could incorporate the auditing procedures in their national programs.
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Affiliation(s)
| | | | | | | | | | - Mehenna Arib
- Centre De Recherche Nucleaire D’alger, Alger Gare, Algeria
| | | | | | - Luo Suming
- Chinese Centre for Disease Control and Prevention, Beijing, China
| | | | - Wojciech Bulski
- Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Warsaw, Poland
| | - Dietmar Georg
- Medical University of Vienna, Vienna, Austria
- Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna, Austria
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Tillner F, Thute P, Löck S, Dietrich A, Fursov A, Haase R, Lukas M, Rimarzig B, Sobiella M, Krause M, Baumann M, Bütof R, Enghardt W. Precise image-guided irradiation of small animals: a flexible non-profit platform. Phys Med Biol 2016; 61:3084-108. [DOI: 10.1088/0031-9155/61/8/3084] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Alabdoaburas MM, Mege JP, Chavaudra J, Bezin JV, Veres A, de Vathaire F, Lefkopoulos D, Diallo I. Experimental assessment of out-of-field dose components in high energy electron beams used in external beam radiotherapy. J Appl Clin Med Phys 2015; 16:435–448. [PMID: 26699572 PMCID: PMC5691002 DOI: 10.1120/jacmp.v16i6.5616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 08/11/2015] [Accepted: 05/17/2015] [Indexed: 11/23/2022] Open
Abstract
The purpose of this work was to experimentally investigate the out-of-field dose in a water phantom, with several high energy electron beams used in external beam radiotherapy (RT). The study was carried out for 6, 9, 12, and 18 MeV electron beams, on three different linear accelerators, each equipped with a specific applicator. Measurements were performed in a water phantom, at different depths, for different applicator sizes, and off-axis distances up to 70 cm from beam central axis (CAX). Thermoluminescent powder dosimeters (TLD-700) were used. For given cases, TLD measurements were compared to EBT3 films and parallel-plane ionization chamber measurements. Also, out-of-field doses at 10 cm depth, with and without applicator, were evaluated. With the Siemens applicators, a peak dose appears at about 12-15 cm out of the field edge, at 1 cm depth, for all field sizes and energies. For the Siemens Primus, with a 10 × 10 cm(²) applicator, this peak reaches 2.3%, 1%, 0.9% and 1.3% of the maximum central axis dose (Dmax) for 6, 9, 12 and 18 MeV electron beams, respectively. For the Siemens Oncor, with a 10 × 10 cm(²) applicator, this peak dose reaches 0.8%, 1%, 1.4%, and 1.6% of Dmax for 6, 9, 12, and 14 MeV, respectively, and these values increase with applicator size. For the Varian 2300C/D, the doses at 12.5 cm out of the field edge are 0.3%, 0.6%, 0.5%, and 1.1% of Dmax for 6, 9, 12, and 18 MeV, respectively, and increase with applicator size. No peak dose is evidenced for the Varian applicator for these energies. In summary, the out-of-field dose from electron beams increases with the beam energy and the applicator size, and decreases with the distance from the beam central axis and the depth in water. It also considerably depends on the applicator types. Our results can be of interest for the dose estimations delivered in healthy tissues outside the treatment field for the RT patient, as well as in studies exploring RT long-term effects.
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Affiliation(s)
- Mohamad M Alabdoaburas
- Inserm (CESP, Centre for Research in Epidemiology and Population Health) U1018, Institut Gustave Roussy and Université Paris-Sud.
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Beyreuther E, Karsch L, Laschinsky L, Leßmann E, Naumburger D, Oppelt M, Richter C, Schürer M, Woithe J, Pawelke J. Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate. Int J Radiat Biol 2015; 91:643-52. [PMID: 25968557 DOI: 10.3109/09553002.2015.1043755] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. MATERIALS AND METHODS The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. RESULTS The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. CONCLUSIONS The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.
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Affiliation(s)
- Elke Beyreuther
- a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany
| | - Leonhard Karsch
- b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Lydia Laschinsky
- a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.,b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Elisabeth Leßmann
- a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany
| | - Doreen Naumburger
- b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Melanie Oppelt
- b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Christian Richter
- a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.,b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany.,c Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.,d German Cancer Consortium (DKTK), Dresden, Germany and German Cancer Research Center (DKFZ) , Heidelberg , Germany
| | - Michael Schürer
- b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Julia Woithe
- b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
| | - Jörg Pawelke
- a Helmholtz-Zentrum Dresden - Rossendorf , Bautzner Landstraße 400, Dresden , Germany.,b OncoRay - National Center for Radiation Research in Oncology , Dresden , Germany
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Oppelt M, Baumann M, Bergmann R, Beyreuther E, Brüchner K, Hartmann J, Karsch L, Krause M, Laschinsky L, Leßmann E, Nicolai M, Reuter M, Richter C, Sävert A, Schnell M, Schürer M, Woithe J, Kaluza M, Pawelke J. Comparison study of in vivo dose response to laser-driven versus conventional electron beam. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2015; 54:155-166. [PMID: 25600561 DOI: 10.1007/s00411-014-0582-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/20/2014] [Indexed: 06/04/2023]
Abstract
The long-term goal to integrate laser-based particle accelerators into radiotherapy clinics not only requires technological development of high-intensity lasers and new techniques for beam detection and dose delivery, but also characterization of the biological consequences of this new particle beam quality, i.e. ultra-short, ultra-intense pulses. In the present work, we describe successful in vivo experiments with laser-driven electron pulses by utilization of a small tumour model on the mouse ear for the human squamous cell carcinoma model FaDu. The already established in vitro irradiation technology at the laser system JETI was further enhanced for 3D tumour irradiation in vivo in terms of beam transport, beam monitoring, dose delivery and dosimetry in order to precisely apply a prescribed dose to each tumour in full-scale radiobiological experiments. Tumour growth delay was determined after irradiation with doses of 3 and 6 Gy by laser-accelerated electrons. Reference irradiation was performed with continuous electron beams at a clinical linear accelerator in order to both validate the dedicated dosimetry employed for laser-accelerated JETI electrons and above all review the biological results. No significant difference in radiation-induced tumour growth delay was revealed for the two investigated electron beams. These data provide evidence that the ultra-high dose rate generated by laser acceleration does not impact the biological effectiveness of the particles.
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Affiliation(s)
- Melanie Oppelt
- OncoRay - National Center for Radiation Research in Oncology, Technische Universität Dresden, Dresden, Germany,
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Morrison H, Menon G, Sloboda RS. Radiochromic film calibration for low-energy seed brachytherapy dose measurement. Med Phys 2015; 41:072101. [PMID: 24989396 DOI: 10.1118/1.4881146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Radiochromic film dosimetry is typically performed for high energy photons and moderate doses characterizing external beam radiotherapy (XRT). The purpose of this study was to investigate the accuracy of previously established film calibration procedures used in XRT when applied to low-energy, seed-based brachytherapy at higher doses, and to determine necessary modifications to achieve similar accuracy in absolute dose measurements. METHODS Gafchromic EBT3 film was used to measure radiation doses upwards of 35 Gy from 75 kVp, 200 kVp, 6 MV, and (∼28 keV) I-125 photon sources. For the latter irradiations a custom phantom was built to hold a single I-125 seed. Film pieces were scanned with an Epson 10000XL flatbed scanner and the resulting 48-bit RGB TIFF images were analyzed using both FilmQA Pro software andMATLAB. Calibration curves relating dose and optical density via a rational functional form for all three color channels at each irradiation energy were determined with and without the inclusion of uncertainties in the measured optical densities and dose values. The accuracy of calibration curve variations obtained using piecewise fitting, a reduced film measurement area for I-125 irradiation, and a reduced number of dose levels was also investigated. The energy dependence of the film lot used was also analyzed by calculating normalized optical density values. RESULTS Slight differences were found in the resulting calibration curves for the various fitting methods used. The accuracy of the calibration curves was found to improve at low doses and worsen at high doses when including uncertainties in optical densities and doses, which may better represent the variability that could be seen in film optical density measurements. When exposing the films to doses > 8 Gy, two-segment piecewise fitting was found to be necessary to achieve similar accuracies in absolute dose measurements as when using smaller dose ranges. When reducing the film measurement area for the I-125 irradiations, the accuracy of the calibration curve was degraded due to the presence of localized film heterogeneities. No degradation in the calibration curves was found when reducing the number of calibration points down to only 4, but with piecewise fitting, 6 calibration points as well as a blank film are required. Variations due to photon energy in film optical density of up to 3% were found above doses of 2 Gy. CONCLUSIONS A modified procedure for performing EBT3 film calibration was established for use with low-energy brachytherapy seeds and high dose exposures. The energy dependence between 6 MV and I-125 photons is significant such that film calibrations should be done with an appropriately low-energy source when performing low-energy brachytherapy dose measurements. Two-segment piecewise fitting with the inclusion of errors in measured optical density as well as dose was found to result in the most accurate calibration curves. Above doses of 1 Gy, absolute dose measurements can be made with an accuracy of 1.6% for 6 MV beams and 5.7% for I-125 seed exposures if using the I-125 source for calibration, or 2.3% if using the 75 kVp photon beam for calibration.
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Affiliation(s)
- Hali Morrison
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Geetha Menon
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Ron S Sloboda
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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Hermida-López M, Lüdemann L, Flühs A, Brualla L. Technical Note: Influence of the phantom material on the absorbed-dose energy dependence of the EBT3 radiochromic film for photons in the energy range 3 keV-18 MeV. Med Phys 2014; 41:112103. [DOI: 10.1118/1.4898598] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Méndez I, Peterlin P, Hudej R, Strojnik A, Casar B. On multichannel film dosimetry with channel-independent perturbations. Med Phys 2014; 41:011705. [PMID: 24387497 DOI: 10.1118/1.4845095] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Different multichannel methods for film dosimetry have been proposed in the literature. Two of them are the weighted mean method and the method put forth by Micke et al. ["Multichannel film dosimetry with nonuniformity correction," Med. Phys. 38, 2523-2534 (2011)] and Mayer et al. ["Enhanced dosimetry procedures and assessment for EBT2 radiochromic film," Med. Phys. 39, 2147-2155 (2012)]. The purpose of this work was to compare their results and to develop a generalized channel-independent perturbations framework in which both methods enter as special cases. METHODS Four models of channel-independent perturbations were compared: weighted mean, Micke-Mayer method, uniform distribution, and truncated normal distribution. A closed-form formula to calculate film doses and the associated type B uncertainty for all four models was deduced. To evaluate the models, film dose distributions were compared with planned and measured dose distributions. At the same time, several elements of the dosimetry process were compared: film type EBT2 versus EBT3, different waiting-time windows, reflection mode versus transmission mode scanning, and planned versus measured dose distribution for film calibration and for γ-index analysis. The methods and the models described in this study are publicly accessible through IRISEU. Alpha 1.1 (http://www.iriseu.com). IRISEU. is a cloud computing web application for calibration and dosimetry of radiochromic films. RESULTS The truncated normal distribution model provided the best agreement between film and reference doses, both for calibration and γ-index verification, and proved itself superior to both the weighted mean model, which neglects correlations between the channels, and the Micke-Mayer model, whose accuracy depends on the properties of the sensitometric curves. With respect to the selection of dosimetry protocol, no significant differences were found between transmission and reflection mode scanning, between 75 ± 5 min and 20 ± 1 h waiting-time windows or between employing EBT2 or EBT3 films. Significantly better results were obtained when a measured dose distribution was used instead of a planned one as reference for the calibration, and when a planned dose distribution was used instead of a measured one as evaluation for the γ-analysis. CONCLUSIONS The truncated normal distribution model of channel-independent perturbations was found superior to the other three models under comparison and the authors propose its use for multichannel dosimetry.
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Affiliation(s)
- I Méndez
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
| | - P Peterlin
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
| | - R Hudej
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
| | - A Strojnik
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
| | - B Casar
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
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McCaw TJ, Micka JA, DeWerd LA. Development and characterization of a three-dimensional radiochromic film stack dosimeter for megavoltage photon beam dosimetry. Med Phys 2014; 41:052104. [DOI: 10.1118/1.4871781] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Zygmanski P, Abkai C, Han Z, Shulevich Y, Menichelli D, Hesser J. Low-cost flexible thin-film detector for medical dosimetry applications. J Appl Clin Med Phys 2014; 15:4454. [PMID: 24710432 PMCID: PMC5875488 DOI: 10.1120/jacmp.v15i2.4454] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 11/22/2013] [Accepted: 11/20/2013] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study is to characterize dosimetric properties of thin film photovoltaic sensors as a platform for development of prototype dose verification equipment in radiotherapy. Towards this goal, flexible thin‐film sensors of dose with embedded data acquisition electronics and wireless data transmission are prototyped and tested in kV and MV photon beams. Fundamental dosimetric properties are determined in view of a specific application to dose verification in multiple planes or curved surfaces inside a phantom. Uniqueness of the new thin‐film sensors consists in their mechanical properties, low‐power operation, and low‐cost. They are thinner and more flexible than dosimetric films. In principle, each thin‐film sensor can be fabricated in any size (mm2 – cm2 areas) and shape. Individual sensors can be put together in an array of sensors spreading over large areas and yet being light. Photovoltaic mode of charge collection (of electrons and holes) does not require external electric field applied to the sensor, and this implies simplicity of data acquisition electronics and low power operation. The prototype device use for testing consists of several thin film dose sensors, each of about 1.5 cm×5 cm area, connected to simple readout electronics. Sensitivity of the sensors is determined per unit area and compared to EPID sensitivity, as well as other standard photodiodes. Each sensor independently measures dose and is based on commercially available flexible thin‐film aSi photodiodes. Readout electronics consists of an ultra low‐power microcontroller, radio frequency transmitter, and a low‐noise amplification circuit implemented on a flexible printed circuit board. Detector output is digitized and transmitted wirelessly to an external host computer where it is integrated and processed. A megavoltage medical linear accelerator (Varian Tx) equipped with kilovoltage online imaging system and a Cobalt source are use to irradiate different thin‐film detector sensors in a Solid Water phantom under various irradiation conditions. Different factors are considered in characterization of the device attributes: energies (80 kVp, 130 kVp, 6 MV, 15 MV), dose rates (different ms × mA, 100–600 MU/min), total doses (0.1 cGy‐500 cGy), depths (0.5 cm–20 cm), irradiation angles with respect to the detector surface (0°‐180°), and IMRT tests (closed MLC, sweeping gap). The detector response to MV radiation is both linear with total dose (~1‐400 cGy) and independent of dose rate (100‐600 Mu/min). The sensitivity per unit area of thin‐film sensors is lower than for aSi flat‐panel detectors, but sufficient to acquire stable and accurate signals during irradiations. The proposed thin‐film photodiode system has properties which make it promising for clinical dosimetry. Due to the mechanical flexibility of each sensor and readout electronics, low‐cost, and wireless data acquisition, it could be considered for quality assurance (e.g., IMRT, mechanical linac QA), as well as real‐time dose monitoring in challenging setup configurations, including large area and 3D detection (multiple planes or curved surfaces). PACS number: 87.56.Fc
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Affiliation(s)
- P Zygmanski
- Brigham and Women's Hospital, Harvard Medical School.
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Brüchner K, Beyreuther E, Baumann M, Krause M, Oppelt M, Pawelke J. Establishment of a small animal tumour model for in vivo studies with low energy laser accelerated particles. Radiat Oncol 2014; 9:57. [PMID: 24533586 PMCID: PMC3936820 DOI: 10.1186/1748-717x-9-57] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 02/10/2014] [Indexed: 12/12/2022] Open
Abstract
Background The long-term aim of developing a laser based acceleration of protons and ions towards clinical application requires not only substantial technological progress, but also the radiobiological characterization of the resulting ultra-short pulsed particle beams. Recent in vitro data showed similar effects of laser-accelerated versus "conventional" protons on clonogenic cell survival. As the proton energies currently achieved by laser driven acceleration are too low to penetrate standard tumour models on mouse legs, the aim of the present work was to establish a tumour model allowing for the penetration of low energy protons (~ 20 MeV) to further verify their effects in vivo. Methods KHT mouse sarcoma cells were injected subcutaneously in the right ear of NMRI (nu/nu) mice and the growing tumours were characterized with respect to growth parameters, histology and radiation response. In parallel, the laser system JETI was prepared for animal experimentation, i.e. a new irradiation setup was implemented and the laser parameters were carefully adjusted. Finally, a proof-of-principle experiment with laser accelerated electrons was performed to validate the tumour model under realistic conditions, i.e. altered environment and horizontal beam delivery. Results KHT sarcoma on mice ears showed a high take rate and continuous tumour growth after reaching a volume of ~ 5 mm3. The first irradiation experiment using laser accelerated electrons versus 200 kV X-rays was successfully performed and tumour growth delay was evaluated. Comparable tumour growth delay was found between X-ray and laser accelerated electron irradiation. Moreover, experimental influences, like anaesthesia and positioning at JETI, were found to be negligible. Conclusion A small animal tumour model suitable for the irradiation with low energy particles was established and validated at a laser based particle accelerator. Thus, the translation from in vitro to in vivo experimentation was for the first time realized allowing a broader preclinical validation of radiobiological characteristics and efficacy of laser driven particle accelerators in the future.
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Affiliation(s)
- Kerstin Brüchner
- Department of Radiation Oncology, University Hospital Carl Gustav Carus, TU Dresden, Fetscherstr, 74, 01307 Dresden, Germany.
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Bekerat H, Devic S, DeBlois F, Singh K, Sarfehnia A, Seuntjens J, Shih S, Yu X, Lewis D. Improving the energy response of external beam therapy (EBT) GafChromicTM
dosimetry films at low energies (≤100 keV). Med Phys 2014; 41:022101. [DOI: 10.1118/1.4860157] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Brown TAD, Hogstrom KR, Alvarez D, Matthews KL, Ham K, Dugas JP. Dose-response curve of EBT, EBT2, and EBT3 radiochromic films to synchrotron-produced monochromatic x-ray beams. Med Phys 2013; 39:7412-7. [PMID: 23231291 DOI: 10.1118/1.4767770] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This work investigates the dose-response curves of GAFCHROMIC(®) EBT, EBT2, and EBT3 radiochromic films using synchrotron-produced monochromatic x-ray beams. EBT2 film is being utilized for dose verification in photoactivated Auger electron therapy at the Louisiana State University Center for Advanced Microstructures and Devices (CAMD) synchrotron facility. METHODS Monochromatic beams of 25, 30, and 35 keV were generated on the tomography beamline at CAMD. Ion chamber depth-dose measurements were used to determine the dose delivered to films irradiated at depths from 0.7 to 8.5 cm in a 10 × 10 × 10-cm(3) polymethylmethacrylate phantom. AAPM TG-61 protocol was applied to convert measured ionization into dose. Films were digitized using an Epson 1680 Professional flatbed scanner and analyzed using the net optical density (NOD) derived from the red channel. A dose-response curve was obtained at 35 keV for EBT film, and at 25, 30, and 35 keV for EBT2 and EBT3 films. Calibrations of films for 4 MV x-rays were obtained for comparison using a radiotherapy accelerator at Mary Bird Perkins Cancer Center. RESULTS The sensitivity (NOD per unit dose) of EBT film at 35 keV relative to that for 4-MV x-rays was 0.73 and 0.76 for doses 50 and 100 cGy, respectively. The sensitivity of EBT2 film at 25, 30, and 35 keV relative to that for 4-MV x-rays varied from 1.09-1.07, 1.23-1.17, and 1.27-1.19 for doses 50-200 cGy, respectively. For EBT3 film the relative sensitivity was within 3% of unity for all three monochromatic x-ray beams. CONCLUSIONS EBT and EBT2 film sensitivity showed strong energy dependence over an energy range of 25 keV-4 MV, although this dependence becomes weaker for larger doses. EBT3 film shows weak energy dependence, indicating that it would be a better dosimeter for kV x-ray beams where beam hardening effects can result in large changes in the effective energy.
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Assmann W, Becker R, Otto H, Bader M, Clemente L, Reinhardt S, Schäfer C, Schirra J, Uschold S, Welzmüller A, Sroka R. 32P-haltige Folien als Implantate für die LDR-Brachytherapie gutartiger Stenosen in der Urologie und Gastroenterologie. Z Med Phys 2013; 23:21-32. [DOI: 10.1016/j.zemedi.2012.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/23/2012] [Accepted: 07/23/2012] [Indexed: 11/27/2022]
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Girard F, Bouchard H, Lacroix F. Reference dosimetry using radiochromic film. J Appl Clin Med Phys 2012; 13:3994. [PMID: 23149793 PMCID: PMC5718535 DOI: 10.1120/jacmp.v13i6.3994] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 06/27/2012] [Accepted: 07/22/2012] [Indexed: 11/23/2022] Open
Abstract
The objectives of this study are to identify and quantify factors that influence radiochromic film dose response and to determine whether such films are suitable for reference dosimetry. The influence of several parameters that may introduce systematic dose errors when performing reference dose measurements were investigated. The effect of the film storage temperature was determined by comparing the performance of three lots of GAFCHROMIC EBT2 films stored at either 4ºC or room temperature. The effect of high (> 80%) or low (< 20%) relative humidity was also determined. Doses measured in optimal conditions with EBT and EBT2 films were then compared with an A12 ionization chamber measurement. Intensity-modulated radiation therapy quality controls using EBT2 films were also performed in reference dose. The results obtained using reference dose measurements were compared with those obtained using relative dose measurements. Storing the film at 4ºC improves the stability of the film over time, but does not eliminate the noncatalytic film development, seen as a rise in optical density over time in the absence of radiation. Relative humidity variations ranging from 80% to 20% have a strong impact on the optical density and could introduce dose errors of up to 15% if the humidity were not controlled during the film storage period. During the scanning procedure, the film temperature influences the optical density that is measured. When controlling for these three parameters, the dose differences between EBT or EBT2 and the A12 chamber are found to be within ± 4% (2σ level) over a dose range of 20-350 cGy. Our results also demonstrate the limitation of the Anisotropic Analytical Algorithm for dose calculation of highly modulated treatment plans.
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Affiliation(s)
- Frédéric Girard
- Département de Radio-Oncologie, Centre hospitalier de l’Université de Montréal (CHUM), Montréal, Québec, Canada.
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Choo JY, Park CM, Lee NK, Lee SM, Lee HJ, Goo JM. Percutaneous transthoracic needle biopsy of small (≤ 1 cm) lung nodules under C-arm cone-beam CT virtual navigation guidance. Eur Radiol 2012; 23:712-9. [PMID: 22976917 DOI: 10.1007/s00330-012-2644-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/11/2012] [Accepted: 08/14/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVES To describe our initial experience with percutaneous transthoracic needle biopsy (PCNB) of small (≤1 cm) lung nodules using a cone-beam computed tomography (CBCT) virtual navigation guidance system in 105 consecutive patients. METHODS One hundred and five consecutive patients (55 male, 50 female; mean age, 62 years) with 107 small (≤1 cm) lung nodules (mean size, 0.85 cm ± 0.14) underwent PCNBs under CBCT virtual-navigation guidance system and constituted our study population. Procedural details-including radiation dose, sensitivity, specificity, diagnostic accuracy and complication rates of CBCT virtual navigation guided PCNBs-were described. RESULTS The mean number of pleural passages with the coaxial needle, biopsies, CT acquisitions, total procedure time, coaxial introducer dwelling time, and estimated radiation exposure during PCNBs were 1.03 ± 0.21, 3.1 ± 0.7, 3.4 ± 1.3, 10.5 min ± 3.2 and 7.2 min ± 2.5, and 5.72 mSv ± 4.19, respectively. Sixty nodules (56.1 %) were diagnosed as malignant, 38 (35.5 %) as benign and nine (8.4 %) as indeterminate. The sensitivity, specificity, and diagnostic accuracy of CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules were 96.7 % (58/60), 100 % (38/38) and 98.0 % (96/98), respectively. Complications occurred in 13 (12.1 %) cases; pneumothorax in seven (6.5 %) and haemoptysis in six (5.6 %). CONCLUSION CBCT virtual-navigation-guided PCNB is a highly accurate and safe diagnostic method for small (≤1 cm) nodules.
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Affiliation(s)
- Ji Yung Choo
- Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, South Korea
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Perez-Calatayud J, Ballester F, Das RK, Dewerd LA, Ibbott GS, Meigooni AS, Ouhib Z, Rivard MJ, Sloboda RS, Williamson JF. Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO. Med Phys 2012; 39:2904-29. [PMID: 22559663 DOI: 10.1118/1.3703892] [Citation(s) in RCA: 196] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Jose Perez-Calatayud
- Radiotherapy Department, La Fe Polytechnic and University Hospital, Valencia, Spain
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Karsch L, Beyreuther E, Burris-Mog T, Kraft S, Richter C, Zeil K, Pawelke J. Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors. Med Phys 2012; 39:2447-55. [DOI: 10.1118/1.3700400] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Avanzo M, Rink A, Dassie A, Massarut S, Roncadin M, Borsatti E, Capra E. In vivodosimetry with radiochromic films in low-voltage intraoperative radiotherapy of the breast. Med Phys 2012; 39:2359-68. [DOI: 10.1118/1.3700175] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dosimetric evaluation of internal shielding in a high dose rate skin applicator. J Contemp Brachytherapy 2011; 3:32-35. [PMID: 27877198 PMCID: PMC5108835 DOI: 10.5114/jcb.2011.21041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 03/01/2011] [Indexed: 11/19/2022] Open
Abstract
Purpose The Valencia HDR applicators are accessories of the microSelectron HDR afterloading system (Nucletron) shaped as truncated cones. The base of the cone is either 2 or 3 cm diameter. They are intended to treat skin lesions, being the typical prescription depth 3 mm. In patients with eyelid lesions, an internal shielding is very useful to reduce the dose to the ocular globe. The purpose of this work was to evaluate the dose enhancement from potential backscatter and electron contamination due to the shielding. Material and methods Two methods were used: a) Monte Carlo simulation, performed with the GEANT4 code, 2 cm Valencia applicator was placed on the surface of a water phantom in which 2 mm lead slab was located at 3 mm depth; b) radiochromic EBT films, used to verify the Monte Carlo results, positioning the films at 1.5, 3, 5 and 7 mm depth, inside the phantom. Two irradiations, with and without the lead shielding slab, were carried out. Results The Monte Carlo results showed that due to the backscatter component from the lead, the dose level raised to about 200% with a depth range of 0.5 mm. Under the lead the dose level was enhanced to about 130% with a depth range of 1 mm. Two millimeters of lead reduce the dose under the slab with about 60%. These results agree with film measurements within uncertainties. Conclusions In conclusion, the use of 2 mm internal lead shielding in eyelid skin treatments with the Valencia applicators were evaluated using MC methods and EBT film dosimetry. The minimum bolus thickness that was needed above and below the shielding was 0.5 mm and 1 mm respectively, and the shielding reduced the absorbed dose delivered to the ocular globe by about 60%.
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DeWerd LA, Ibbott GS, Meigooni AS, Mitch MG, Rivard MJ, Stump KE, Thomadsen BR, Venselaar JLM. A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: report of AAPM Task Group No. 138 and GEC-ESTRO. Med Phys 2011; 38:782-801. [PMID: 21452716 PMCID: PMC3033879 DOI: 10.1118/1.3533720] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 12/06/2010] [Accepted: 12/14/2010] [Indexed: 11/07/2022] Open
Abstract
This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.
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Affiliation(s)
- Larry A DeWerd
- Department of Medical Physics and Accredited Dosimetry Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706, USA
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Lacroix F, Guillot M, McEwen M, Cojocaru C, Gingras L, Beddar AS, Beaulieu L. Extraction of depth-dependent perturbation factors for parallel-plate chambers in electron beams using a plastic scintillation detector. Med Phys 2010; 37:4331-42. [PMID: 20879593 DOI: 10.1118/1.3463383] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This work presents the experimental extraction of the overall perturbation factor PQ in megavoltage electron beams for NACP-02 and Roos parallel-plate ionization chambers using a plastic scintillation detector (PSD). METHODS The authors used a single scanning PSD mounted on a high-precision scanning tank to measure depth-dose curves in 6, 12, and 18 MeV clinical electron beams. The authors also measured depth-dose curves using the NACP-02 and PTW Roos chambers. RESULTS The authors found that the perturbation factors for the NACP-02 and Roos chambers increased substantially with depth, especially for low-energy electron beams. The experimental results were in good agreement with the results of Monte Carlo simulations reported by other investigators. The authors also found that using an effective point of measurement (EPOM) placed inside the air cavity reduced the variation of perturbation factors with depth and that the optimal EPOM appears to be energy dependent. CONCLUSIONS A PSD can be used to experimentally extract perturbation factors for ionization chambers. The dosimetry protocol recommendations indicating that the point of measurement be placed on the inside face of the front window appear to be incorrect for parallel-plate chambers and result in errors in the R50 of approximately 0.4 mm at 6 MeV, 1.0 mm at 12 MeV, and 1.2 mm at 18 MeV.
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Affiliation(s)
- Frédéric Lacroix
- Département de Radio-Oncologie, Centre hospitalier de l'Université de Montréal, Québec, Canada.
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Arjomandy B, Tailor R, Anand A, Sahoo N, Gillin M, Prado K, Vicic M. Energy dependence and dose response of Gafchromic EBT2 film over a wide range of photon, electron, and proton beam energies. Med Phys 2010; 37:1942-7. [PMID: 20527528 DOI: 10.1118/1.3373523] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Since the Gafchromic film EBT has been recently replaced by the newer model EBT2, its characterization, especially energy dependence, has become critically important. The energy dependence of the dose response of Gafchromic EBT2 film is evaluated for a broad range of energies from different radiation sources used in radiation therapy. METHODS The beams used for this study comprised of kilovoltage x rays (75, 125, and 250 kVp), 137Cs gamma (662 KeV), 60Co gamma (1.17-1.33 MeV), megavoltage x rays (6 and 18 MV), electron beams (6 and 20 MeV), and proton beams (100 and 250 MeV). The film's response to each of the above energies was measured over the dose range of 0.4-10 Gy, which corresponds to optical densities ranging from 0.05 to 0.74 for the film reader used. RESULTS The energy dependence of EBT2 was found to be relatively small within measurement uncertainties (1 sigma = +/- 4.5%) for all energies and modalities. CONCLUSION For relative and absolute dosimetry of radiation therapy beams, the weak energy dependence of the EBT2 makes it most suitable for clinical use compared to other films.
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Affiliation(s)
- Bijan Arjomandy
- Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, Texas 77030, USA.
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Desroches J, Bouchard H, Lacroix F. Potential errors in optical density measurements due to scanning side in EBT and EBT2 Gafchromic film dosimetry. Med Phys 2010; 37:1565-70. [PMID: 20443477 DOI: 10.1118/1.3355895] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study is to determine the effect on the measured optical density of scanning on either side of a Gafchromic EBT and EBT2 film using an Epson (Epson Canada Ltd., Toronto, Ontario) 10000XL flat bed scanner. METHODS Calibration curves were constructed using EBT2 film scanned in landscape orientation in both reflection and transmission mode on an Epson 10000XL scanner. Calibration curves were also constructed using EBT film. Potential errors due to an optical density difference from scanning the film on either side ("face up" or "face down") were simulated. RESULTS Scanning the film face up or face down on the scanner bed while keeping the film angular orientation constant affects the measured optical density when scanning in reflection mode. In contrast, no statistically significant effect was seen when scanning in transmission mode. This effect can significantly affect relative and absolute dose measurements. As an application example, the authors demonstrate potential errors of 17.8% by inverting the film scanning side on the gamma index for 3%-3 mm criteria on a head and neck intensity modulated radiotherapy plan, and errors in absolute dose measurements ranging from 10% to 35% between 2 and 5 Gy. CONCLUSIONS Process consistency is the key to obtaining accurate and precise results in Gafchromic film dosimetry. When scanning in reflection mode, care must be taken to place the film consistently on the same side on the scanner bed.
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Affiliation(s)
- Joannie Desroches
- Département de Radio-Oncologie, Centre hospitalier de l'Université de Montreal, Montréal, Quebec H2L 4M1, Canada
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Sutherland JGH, Rogers DWO. Monte Carlo calculated absorbed-dose energy dependence of EBT and EBT2 film. Med Phys 2010; 37:1110-6. [PMID: 20384246 DOI: 10.1118/1.3301574] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The absorbed-dose energy dependence of GAFCHROMIC EBT and EBT2 film irradiated in photon beams is studied to understand the shape of the curves and the physics behind them. METHODS The absorbed-dose energy dependence is calculated using the EGSnrc-based EGS_chamber and DOSRZnrc codes by calculating the ratio of dose to water to dose to active film layers at photon energies ranging from 3 keV to 18 MeV. These data are compared to the mass energy absorption coefficient ratios and the restricted stopping power ratios of water to active film materials as well as to previous experimental results. RESULTS In the photon energy range of 100 keV to 18 MeV the absorbed-dose energy dependence is found to be energy independent within +/- 0.6%. However, below 100 keV, the absorbed-dose energy dependence of EBT varies by approximately 10% due to changes in mass energy absorption coefficient ratios of water to film materials, as well as an increase in the number of electrons being created and scattered in the central surface layer of the film. Results are found to disagree with previous experimental studies suggesting the possibility of an intrinsic energy dependence at lower photon energies. For EBT2 film the absorbed-dose energy dependence at low photon energies varies by 50% or 10% depending on the manufacturing lot due to changes in the ratio of mass energy absorption coefficients of the active emulsion layers to water. CONCLUSIONS Caution is recommended when using GAFCHROMIC EBT/EBT2 films at photon energies below 100 keV. It is recommended that the effective atomic number of future films be produced as close to that of water and that thicker active layers are advantageous.
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Affiliation(s)
- J G H Sutherland
- Ottawa Carleton Institute for Physics, Carleton University Campus, Ottawa K1S 5B6, Canada.
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Beyreuther E, Enghardt W, Kaluza M, Karsch L, Laschinsky L, Lessmann E, Nicolai M, Pawelke J, Richter C, Sauerbrey R, Schlenvoigt HP, Baumann M. Establishment of technical prerequisites for cell irradiation experiments with laser-accelerated electrons. Med Phys 2010; 37:1392-400. [DOI: 10.1118/1.3301598] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lindsay P, Rink A, Ruschin M, Jaffray D. Investigation of energy dependence of EBT and EBT-2 Gafchromic film. Med Phys 2010; 37:571-6. [PMID: 20229865 DOI: 10.1118/1.3291622] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Patricia Lindsay
- Department of Radiation Oncology, Radiation Physics, and Princess Margaret Hospital, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
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