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Hosseini FS, Baghani HR, Robatjazi M, Mowlavi AA, Porouhan P. Performance evaluation of buildup bolus during external radiotherapy of mastectomy patients: treatment planning and film dosimetry. Med Biol Eng Comput 2023; 61:435-444. [PMID: 36460872 DOI: 10.1007/s11517-022-02721-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/19/2022] [Indexed: 12/04/2022]
Abstract
A buildup bolus is used during the post-mastectomy radiotherapy (PMRT) to overcome under-dosage issues in the chest wall. The current study is aimed at evaluating the performance of a bolus in dose enhancement through both film dosimetry and treatment planning approaches. Twenty patients were enrolled in current research. The received dose by the skin at the lateral and medial regions of the chest wall in the presence and absence bolus was evaluated. Film dosimetry results showed that the presence of the bolus can averagely increase the skin dose by about 80% (P value < 0.001) and 92% (P value < 0.001) in lateral and medial regions, respectively. No significant difference was observed between the measured and treatment planning system (TPS)-calculated dose values in the presence of bolus. The presence of the bolus can considerably increase the absorbed dose by superficial chest wall regions. The TPS shows a favorable performance in superficial dose calculations in the presence of the buildup bolus. Hosseini et al.: demonstration of implemented research in the current study.
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Affiliation(s)
| | | | - Mostafa Robatjazi
- Medical Physics and Radiological Sciences Department, Sabzevar University of Medical Sciences, Sabzevar, Iran
| | | | - Pejman Porouhan
- Radiation Oncology Department, Sabzevar University of Medical Sciences, Sabzevar, Iran
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On measuring the 3D dose distribution for notched and circular Ru-106 plaque shapes through Gafchromic film dosimetry approach. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2021.109792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Gomez G, Baeza M, Mateos JC, Rivas JA, Simon FJL, Ortega DM, de Los Ángeles Flores Carrión M, Del Campo ER, Gómez-Cía T, Guerra JLL. A three-dimensional printed customized bolus: adapting to the shape of the outer ear. ACTA ACUST UNITED AC 2021; 26:211-217. [PMID: 34211771 DOI: 10.5603/rpor.a2021.0030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 02/02/2021] [Indexed: 11/25/2022]
Abstract
Background The skin-sparing effect of megavoltage-photon beams in radiotherapy (RT) reduces the target coverage of superficial tumours. Consequently, a bolus is widely used to enhance the target coverage for superficial targets. This study evaluates a three-dimensional (3D)-printed customized bolus for a very irregular surface, the outer ear. Materials and methods We fabricated a bolus using a computed tomography (CT) scanner and evaluated its efficacy. The head of an Alderson Rando phantom was scanned with a CT scanner. Two 3D boluses of 5- and 10-mm thickness were designed to fit on the surface of the ear. They were printed by the Stratasys Objet260 Connex3 using the malleable "rubber-like" photopolymer Agilus. CT simulations of the Rando phantom with and without the 3D and commercial high density boluses were performed to evaluate the dosimetric properties of the 3D bolus. The prescription dose to the outer ear was 50 Gy at 2 Gy/fraction. Results We observed that the target coverage was slightly better with the 3D bolus of 10mm compared with the commercial one (D98% 98.2% vs. 97.6%).The maximum dose was reduced by 6.6% with the 3D bolus and the minimum dose increased by 5.2% when comparing with the commercial bolus. In addition, the homogeneity index was better for the 3D bolus (0.041 vs. 0.073). Conclusion We successfully fabricated a customized 3D bolus for a very irregular surface. The target coverage and dosimetric parameters were at least comparable with a commercial bolus. Thus, the use of malleable materials can be considered for the fabrication of customized boluses in cases with complex anatomy.
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Affiliation(s)
- Gorka Gomez
- Biomedical Informatics, Biomedical Engineering and Health Economy, Institute of Biomedicine of Seville (IBIS)/Virgen del Rocío University Hospital/CSIC/University of Seville, Seville, Spain
| | - Montserrat Baeza
- Radiation Physics, University Hospital Virgen del Rocio, Seville, Spain
| | | | | | | | - Diego Mesta Ortega
- Department of Radiation Oncology, University Hospital Virgen del Rocio, Seville, Spain
| | | | - Eleonor Rivin Del Campo
- Department of Radiation Oncology, Tenon University Hospital, Hôpitaux Universitaires Est Parisien, Sorbonne University Medical Faculty, Paris, France
| | - Tomas Gómez-Cía
- Instituto de Biomedicina de Sevilla (IBIS/HUVR/CSIC/Universidad de Sevilla), Seville, Spain.,Department of Plastic Surgery, University Hospital Virgen del Rocio, Seville, Spain
| | - Jose Luis Lopez Guerra
- Department of Radiation Oncology, University Hospital Virgen del Rocio, Seville, Spain.,Instituto de Biomedicina de Sevilla (IBIS/HUVR/CSIC/Universidad de Sevilla), Seville, Spain
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Santos T, Ventura T, Lopes MDC. A review on radiochromic film dosimetry for dose verification in high energy photon beams. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109217] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Santos J, Silva S, Sarmento S. Optimized method for in vivo dosimetry with small films in pelvic IOERT for rectal cancer. Phys Med 2020; 81:20-30. [PMID: 33338728 DOI: 10.1016/j.ejmp.2020.11.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 11/09/2020] [Accepted: 11/15/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Intra-Operative Electron Radiation Therapy (IOERT) is used to treat rectal cancer at our institution, and in vivo measurements with Gafchromic EBT3® films were introduced as quality assurance. The purpose of this work was to quantify the uncertainties associated with digitization of very small EBT3 films irradiated simultaneously, in order to optimize in vivo dosimetry for IOERT. METHODS Film samples of different sizes - M1 (5×5cm2), M2 (1.5×1.5 cm2), M3 (1.0×1.5 cm2) and M4 (0.75×1.5 cm2) - were used to quantify typical variations (uncertainties) due to scanner fluctuations, misalignment, film inhomogeneity, long-term effect of film cutting, small rotations, film curling, edge effects and the influence of opaque templates. Fitting functions and temporal validity of sensitometric curves were also assessed. RESULTS Film curling, intra-film variability and scanner fluctuations are important effects that need to be minimized or considered in the uncertainty budget. Small rotations, misalignments and film cutting have little or no influence on the readings. Most fitting functions perform well, but the quantity used for dose quantification determines over- or under-valuation of dose in the long term. Edge effects and the influence of opaque templates need to be well understood, to allow optimization of methodology to the intended purpose. CONCLUSION The proposed method allows practical and simultaneous digitization of up to ten small irradiated film samples, with an experimental uncertainty of 1%.
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Affiliation(s)
- Joana Santos
- Physics and Astronomy Department, Faculty of Sciences, University of Porto, Portugal; Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal
| | - Sofia Silva
- Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal; Medical Physics Service, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal
| | - Sandra Sarmento
- Management, Outcomes Research and Economics in Healthcare Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal; Medical Physics Service, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
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Selection of gamma analysis acceptance criteria in IMRT QA using Gafchromic EBT3 film dosimetry. JOURNAL OF RADIOTHERAPY IN PRACTICE 2019. [DOI: 10.1017/s1460396918000602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractBackground and purposeThis study reported the justification and selection of acceptable γ criteria with respect to low (6 MV) and high (15 MV) photon beams for intensity-modulated radiation therapy quality assurance (IMRT QA) using the Gafchromic external beam therapy 3 (EBT3) film.Materials and methodsFive-field step-and-shoot IMRT was used to treat 16 brain IMRT patients using the dual-energy DHX-S linear accelerator (Varian Medical System, Palo Alto, CA, USA). Dose comparisons between computed values of the treatment planning system (TPS) and Gafchromic EBT3 film were evaluated based on γ analysis using the Film QA Pro software. The dose distribution was analysed with gamma area histograms (GAHs) generated using different γ criteria (3%/2 mm, 3%/3 mm and 5%/3 mm) for the 6 and 15 MV photon beams, to optimise the best distance-to-agreement (DTA) criteria with respect to the beam energy.ResultsFrom the comparison between the dose distributions acquired from the TPS and EBT3 film, a DTA criterion of 3%/2 mm showed less dose differences (DDs) with passing rates up to 93% for the 6 MV photon beams, while for the 15 MV a relaxed DTA criterion of 5%/3 mm was consistent with the DD acceptability criteria with a 95% passing rate.ConclusionsOur results suggested that high-energy photon beams required relaxed DTA criteria for the brain IMRT QA, while low-energy photon beams showed better results even with tight DTA criteria.
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A novel method for EBT3 Gafchromic films read-out at high dose levels. Phys Med 2019; 61:77-84. [DOI: 10.1016/j.ejmp.2019.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 04/06/2019] [Accepted: 04/16/2019] [Indexed: 11/24/2022] Open
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Baghani HR, Robatjazi M, Mahdavi SR, Nafissi N, Akbari ME. Breast intraoperative electron radiotherapy: Image-based setup verification and in-vivo dosimetry. Phys Med 2019; 60:37-43. [PMID: 31000084 DOI: 10.1016/j.ejmp.2019.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 02/25/2019] [Accepted: 03/19/2019] [Indexed: 10/27/2022] Open
Abstract
INTRODUCTION Single fraction nature of intraoperative radiotherapy highly demands a quality assurance procedure to qualify both beam setup and treatment delivery. The aim of this study is to evaluate the treatment setup during breast intraoperative electron radiotherapy (IOERT) and in-vivo dose delivery verification. MATERIALS AND METHODS Twenty-five breast cancer patients were enrolled and setup verification for each case was performed using C-arm imaging. The received dose by surface and distal end of target was measured by EBT2 film. The significance level of difference between obtained dosimetry results and predicted ones was evaluated by the T statistical test. RESULTS Acquired C-arm images in two different oblique views revealed any misalignment between the applicator and shielding disk. The mean difference between the measured surface dose and expected one was 1.8% ± 1.2 (p = 0.983) while a great disagreement, 11.1% ± 1.5 (p < 0.001), was observed between the measured distal end dose and expected one. This discrepancy is mainly correlated to the backscattering effect from the shielding disk. Target depth nonuniformities can also contribute to this remarkable difference. CONCLUSION Employing the intraoperative imaging for IOERT setup verification can considerably improve the treatment quality. Therefore, it is suggested to implement this imaging procedure as a part of treatment quality assurance. Favorable agreement between the predicted and measured surface doses demonstrates the applicability of EBT2 film for dose delivery verification. The results of in-vivo dosimetry showed that the electron backscattering from employed shielding disk can affect the received dose by the distal end of tumor bed.
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Affiliation(s)
- Hamid Reza Baghani
- Physics Department, Hakim Sabzevari University, Shohada-e Hastei Blvd, P.O. 9617976487, Sabzevar, Iran.
| | - Mostafa Robatjazi
- Department of Medical Physics and Radiological Sciences, Sabzevar University of Medical Sciences, Shohada-e Hastei Blvd, Sabzevar University of Medical Sciences Campus, P.O. 9617913112, Sabzevar, Iran; Vasei Radiotherapy & Oncology Center, Vasei Hospital, P.O. 9617913113, Sabzevar, Iran.
| | - Seied Rabi Mahdavi
- Department of Medical Physics, Iran University of Medical Sciences. Hemmat Exp. Way, Faculty of Medicine, P.O. 14496141525, Tehran, Iran
| | - Nahid Nafissi
- Department of Breast Surgery, Iran University of Medical Sciences. Hemmat Exp. Way, Faculty of Medicine, P.O. 14496141525, Tehran, Iran
| | - Mohammad Esmail Akbari
- Cancer Research Center, Shahid Beheshti University of Medical Sciences, Shohadaye Tajrrish Hospital, Tajrish Sq., P.O. 19996 14414, Tehran, Iran
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Tamponi M, Bona R, Poggiu A, Marini P. A new form of the calibration curve in radiochromic dosimetry. Properties and results. Med Phys 2016; 43:4435. [DOI: 10.1118/1.4954208] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Robatjazi M, Mahdavi SR, Takavr A, Baghani HR. Application of Gafchromic EBT2 film for intraoperative radiation therapy quality assurance. Phys Med 2015; 31:314-9. [PMID: 25703011 DOI: 10.1016/j.ejmp.2015.01.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 01/29/2015] [Accepted: 01/31/2015] [Indexed: 10/24/2022] Open
Abstract
PURPOSE Intraoperative radiation therapy (IORT) using electron beam is commonly done by mobile dedicated linacs that have a variable range of electron energies. This paper focuses on the evaluation of the EBT2 film response in the green and red colour channels for IORT quality assurance (QA). METHODS The calibration of the EBT2 films was done in two ranges; 0-8 Gy for machine QA by red channel and 8-24 Gy for patient-specific QA by green channel analysis. Irradiation of calibration films and relative dosimetries were performed in a water phantom. To evaluate the accuracy of the film response in relative dosimetry, gamma analysis was used to compare the results of the Monte Carlo simulation and ionometric dosimetry. Ten patients with early stage breast cancer were selected for in-vivo dosimetry using the green channel of the EBT2 film. RESULTS The calibration curves were obtained by linear fitting of the green channel and a third-order polynomial function in the red channel (R2=0.99). The total dose uncertainty was up to 4.2% and 4.7% for the red and green channels, respectively. There was a good agreement between the relative dosimetries of films by the red channel, Monte Carlo simulations and ionometric values. The mean dose difference of the in-vivo dosimetry by green channel of this film and the expected values was about 1.98% ± 0.75. CONCLUSION The results of this study showed that EBT2 film can be considered as an appropriate tool for machine and patient-specific QA in IORT.
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Affiliation(s)
- Mostafa Robatjazi
- Department of Medical Physics, Tehran University of Medical Science, Poursina St, 1417614411 Tehran, Iran
| | - Seied Rabi Mahdavi
- Department of Medical Physics, Iran University of Medical Science, Hemmat Exp. Way, 14496141525 Tehran, Iran.
| | - Abbas Takavr
- Department of Medical Physics, Tehran University of Medical Science, Poursina St, 1417614411 Tehran, Iran
| | - Hamid Reza Baghani
- Department of Radiation Medicine, Shahid Beheshti University, Daneshjoo St, Velenjak, 1983963113 Tehran, Iran
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Baghani HR, Aghamiri SMR, Mahdavi SR, Robatjazi M, Zadeh AR, Akbari ME, Mirzaei HR, Nafissi N, Samsami M. Dosimetric evaluation of Gafchromic EBT2 film for breast intraoperative electron radiotherapy verification. Phys Med 2014; 31:37-42. [PMID: 25231546 DOI: 10.1016/j.ejmp.2014.08.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/16/2014] [Accepted: 08/18/2014] [Indexed: 11/16/2022] Open
Abstract
PURPOSE Quality assurance (QA) is one of the most important issues that should be addressed for intraoperative electron radiotherapy (IOERT), which is not benefiting from image-based treatment planning system. The aim of this study is to evaluate the dosimetric characteristics of Gafchromic EBT2 film for breast IOERT QA procedure. METHODS Due to the fact that some dedicated accelerators are being used for IOERT, dependence of the film response to energy, field size, dose rate and incidence angle of electron beam from the LIAC IOERT accelerator was studied. Then, film response curve to breast IOERT doses was obtained and its accuracy was evaluated and justified through comparison to the results of ionometric dosimetry. RESULTS The results of this study indicated that there are no significant differences between the film responses at different energies of 6, 8, 10 and 12 MeV (P-value = 0.99). Similarly, no field size dependency was found when evaluating the response of the film to different field sizes ranging from 4 to 10 cm (P-value = 0.94). Film response was found to be independent of the dose rate of intraoperative electron beam (P-value = 0.12). Film response variations with changing the beam incidence angle were not significant (P-value > 0.8). Calibration curve at the dose range of 8-24 Gy had an acceptable accuracy. The difference between the results of film dosimetry and ionometric dosimetry was around 5% which was in agreement with the results of dose uncertainty estimation. CONCLUSION The EBT2 film was found to be a potentially appropriate tool for breast IOERT verification.
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Affiliation(s)
- Hamid Reza Baghani
- Department of Radiation Medicine, Shahid Beheshti University, Daneshjoo St, Velenjak 1983963113, Tehran, Iran
| | - S Mahmoud Reza Aghamiri
- Department of Radiation Medicine, Shahid Beheshti University, Daneshjoo St, Velenjak 1983963113, Tehran, Iran.
| | - S Rabi Mahdavi
- Department of Medical Physics, Iran University of Medical Science, Hemmat Exp.Way 14496141525, Tehran, Iran
| | - Mostafa Robatjazi
- Department of Medical Physics, Tehran University of Medical Science, Poursina St 1417614411, Tehran, Iran
| | - Arezo Rahim Zadeh
- Department of Medical Radiation, Islamic Azad University, Science and Research Branch, Hesark Blvd 1477893855, Tehran, Iran
| | - Mohammad Esmail Akbari
- Cancer Research Center, Shahid Beheshti University of Medical Science, Shahrdari St 1985717443, Tehran, Iran
| | - Hamid Reza Mirzaei
- Cancer Research Center, Shahid Beheshti University of Medical Science, Shahrdari St 1985717443, Tehran, Iran
| | - Nahid Nafissi
- Cancer Research Center, Shahid Beheshti University of Medical Science, Shahrdari St 1985717443, Tehran, Iran
| | - Majid Samsami
- Cancer Research Center, Shahid Beheshti University of Medical Science, Shahrdari St 1985717443, Tehran, Iran
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Tamponi M, Bona R, Poggiu A, Marini P. A practical tool to evaluate dose distributions using radiochromic film in radiation oncology. Phys Med 2014; 31:31-6. [PMID: 25113942 DOI: 10.1016/j.ejmp.2014.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 07/19/2014] [Accepted: 07/21/2014] [Indexed: 10/24/2022] Open
Abstract
PURPOSE Triple channel algorithm and specific procedures make more reliable radiochromic dosimetry for treatment planning verification and quality assurance in radiation therapy. A tool to obtain radiochromic dose distributions and compare them with the ones resulting from a treatment planning system was developed and applied. METHODS The tool was developed as Microsoft Excel macro; it builds dose calibration curves against net optical density of Gafchromic EBT3 film, produces axial, coronal and sagittal dose maps and allows to evaluate them against dose distributions calculated by the Varian treatment planning system Eclipse using gamma index and gamma angle. RESULTS The net optical density standard errors of estimate of calibration curves at 6 MV Varian DBX600 linac energy were 0.2%, 0.4% and 0.2% for the red, green and blue channels. Tests of these curves by means of three independent eight dose points measurement series, at 15 MV and 6 MV Varian 2100C linac and at 6 MV DBX600 linac energies, showed less than 2% of dose errors for the red channel and less than 3% for the green channel in the range 100-450 cGy. The comparisons between dose distributions from Gafchromic EBT3 triple channel algorithm and the ones from Eclipse analytic anisotropic algorithm (AAA) showed values of gamma index 95th percentile between 0.6 and 1.0. CONCLUSION The obtained results encourage the application of this tool in radiation therapy quality assurance.
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Affiliation(s)
- M Tamponi
- Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy.
| | - R Bona
- Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy
| | - A Poggiu
- Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy
| | - P Marini
- Medical Physics Unit, ASL Sassari, Via Enrico de Nicola, Sassari, Italy
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Mathot M, Sobczak S, Hoornaert MT. Gafchromic film dosimetry: four years experience using FilmQA Pro software and Epson flatbed scanners. Phys Med 2014; 30:871-7. [PMID: 25018050 DOI: 10.1016/j.ejmp.2014.06.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 05/21/2014] [Accepted: 06/23/2014] [Indexed: 10/25/2022] Open
Abstract
PURPOSE s: To assess performance of FilmQA Pro software for pre-treatment patient-specific quality assurance (QA), using radiochromic films and two commercial flatbed scanners. To evaluate a novel multichannel approach compared to the classical red channel evaluation. MATERIAL AND METHODS Patient films (mostly EBT2 films, one box of EBT3) were digitalized using successively two flatbed scanners: the A4-size Epson V750 and the A3-size Epson 10000XL. Prior to patient dose verification, basic characteristics of films and scanners were investigated. Patient films were analyzed using FilmQA Pro software, which enables to use the signal from all three colour channels (Red, Green, Blue). RESULTS Compared to the red channel evaluation, multichannel evaluation presents better passing rates with regard to local gamma index. As expected, we obtained better results using A3-size scanner compared to A4-size scanner, especially when considering large region of interest. An observation of great interest was made for both scanners: after intensive use, a tilting in the blue transmittance profiles appeared in the lamp direction, making multichannel analysis unsuitable for accurate dose evaluation.
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Affiliation(s)
- M Mathot
- Service de Radiothérapie, Centre Hospitalier Universitaire de Liège, Domaine Universitaire du Sart Tilman, B35, 4000 Liège, Belgium.
| | - S Sobczak
- Service de Radiothérapie, Centre Hospitalier Universitaire de Liège, Domaine Universitaire du Sart Tilman, B35, 4000 Liège, Belgium
| | - M-T Hoornaert
- Service de Radiothérapie, Centre Hospitalier Universitaire de Liège, Domaine Universitaire du Sart Tilman, B35, 4000 Liège, Belgium
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Dreindl R, Georg D, Stock M. Radiochromic film dosimetry: considerations on precision and accuracy for EBT2 and EBT3 type films. Z Med Phys 2013; 24:153-63. [PMID: 24055395 DOI: 10.1016/j.zemedi.2013.08.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/13/2013] [Accepted: 08/13/2013] [Indexed: 11/19/2022]
Abstract
Gafchromic® EBT2 film is a widely used dosimetric tool for quality assurance in radiation therapy. In 2012 EBT3 was presented as a replacement for EBT2 films. The symmetric structure of EBT3 films to reduce face-up/down dependency as well as the inclusion of a matte film surface to frustrate Newton Ring artifacts present the most prominent improvements of EBT3 films. The aim of this study was to investigate the characteristics of EBT3 films, to benchmark the films against the known EBT2-features and to evaluate the dosimetric behavior over a time period greater than 6 months. All films were irradiated to clinical photon beams (6 MV, 10 MV and 18 MV) on an Elekta Synergy Linac equipped with a Beam Modulator MLC in solid water phantom slabs. Film digitalization was done with a flatbed transparency scanner (Type Epson Expression 1680 Pro). MATLAB® was used for further statistical calculations and image processing. The investigations on post-irradiation darkening, film orientation, film uniformity and energy dependency resulted in negligible differences between EBT2 and EBT3 film. A minimal improvement in face-up/down dependence was found for EBT3. The matte film surface of EBT3 films turned out to be a practical feature as Newton rings could be eliminated completely. Considering long-term behavior (> 6 months) a shift of the calibration curve for EBT2 and EBT3 films due to changes in the dynamic response of the active component was observed. In conclusion, the new EBT3 film yields comparable results to its predecessor EBT2. The general advantages of radiochromic film dosimeters are completed by high film homogeneity, low energy dependence for the observed energy range and a minimized face-up/down dependence. EBT2 dosimetry-protocols can also be used for EBT3 films, but the inclusion of periodical recalibration-interval (e.g. once a quarter) is recommended for protocols of both film generations.
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Affiliation(s)
- Ralf Dreindl
- Department of Radiooncology, Comprehensive Cancer Center, Medical University of Vienna/Vienna General Hospital; EBG MedAustron GmbH, Marie-Curie-Straße 5, 2700 Wiener Neustadt, Austria
| | - Dietmar Georg
- Department of Radiooncology, Comprehensive Cancer Center, Medical University of Vienna/Vienna General Hospital; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna
| | - Markus Stock
- Department of Radiooncology, Comprehensive Cancer Center, Medical University of Vienna/Vienna General Hospital; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna.
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Palmer AL, Di Pietro P, Alobaidli S, Issa F, Doran S, Bradley D, Nisbet A. Comparison of methods for the measurement of radiation dose distributions in high dose rate (HDR) brachytherapy: Ge-doped optical fiber, EBT3 Gafchromic film, and PRESAGE® radiochromic plastic. Med Phys 2013; 40:061707. [PMID: 23718586 DOI: 10.1118/1.4805100] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Dose distribution measurement in clinical high dose rate (HDR) brachytherapy is challenging, because of the high dose gradients, large dose variations, and small scale, but it is essential to verify accurate treatment planning and treatment equipment performance. The authors compare and evaluate three dosimetry systems for potential use in brachytherapy dose distribution measurement: Ge-doped optical fibers, EBT3 Gafchromic film with multichannel analysis, and the radiochromic material PRESAGE(®) with optical-CT readout. METHODS Ge-doped SiO2 fibers with 6 μm active core and 5.0 mm length were sensitivity-batched and their thermoluminescent properties used via conventional heating and annealing cycles. EBT3 Gafchromic film of 30 μm active thickness was calibrated in three color channels using a nominal 6 MV linear accelerator. A 48-bit transmission scanner and advanced multichannel analysis method were utilized to derive dose measurements. Samples of the solid radiochromic polymer PRESAGE(®), 60 mm diameter and 100 mm height, were analyzed with a parallel beam optical CT scanner. Each dosimetry system was used to measure the dose as a function of radial distance from a Co-60 HDR source, with results compared to Monte Carlo TG-43 model data. Each system was then used to measure the dose distribution along one or more lines through typical clinical dose distributions for cervix brachytherapy, with results compared to treatment planning system (TPS) calculations. Purpose-designed test objects constructed of Solid Water and held within a full-scatter water tank were utilized. RESULTS All three dosimetry systems reproduced the general shape of the isolated source radial dose function and the TPS dose distribution. However, the dynamic range of EBT3 exceeded those of doped optical fibers and PRESAGE(®), and the latter two suffered from unacceptable noise and artifact. For the experimental conditions used in this study, the useful range from an isolated HDR source was 5-40 mm for fibers, 3-50 mm for EBT3, and 4-21 mm for PRESAGE(®). Fibers demonstrated some over-response at very low dose levels, suffered from volume averaging effects in the dose distribution measurement, and exhibited up to 9% repeatability variation over three repeated measurements. EBT3 demonstrated excellent agreement with Monte Carlo and TPS dose distributions, with up to 3% repeatability over three measurements. PRESAGE(®) gave promising results, being the only true 3D dosimeter, but artifacts and noise were apparent. CONCLUSIONS The comparative response of three emerging dosimetry systems for clinical brachytherapy dose distribution measurement has been investigated. Ge-doped optical fibers have excellent spatial resolution for single-direction measurement but are currently too large for complex dose distribution assessment. The use of PRESAGE(®) with optical-CT readout gave promising results in the measurement of true 3D dose distributions but further development work is required to reduce noise and improve dynamic range for brachytherapy dose distribution measurements. EBT3 Gafchromic film with multichannel analysis demonstrated accurate and reproducible measurement of dose distributions in HDR brachytherapy. Calibrated dose measurements were possible with agreement within 1.5% of TPS dose calculations. The suitability of EBT3 as a dosimeter for 2D quality control or commissioning work has been demonstrated.
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Affiliation(s)
- A L Palmer
- Department of Physics, Faculty of Engineering and Physical Science, University of Surrey, Surrey GU2 7JP, United Kingdom.
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