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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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Esposito G, Anello P, Pecchia I, Tabocchini MA, Campa A. Facility for gamma irradiations of cultured cells at low dose rates: design, physical characteristics and functioning. Appl Radiat Isot 2016; 115:227-234. [DOI: 10.1016/j.apradiso.2016.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 06/09/2016] [Accepted: 06/18/2016] [Indexed: 11/28/2022]
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Marrazzo L, Zani M, Pallotta S, Arilli C, Casati M, Compagnucci A, Talamonti C, Bucciolini M. GafChromic(®) EBT3 films for patient specific IMRT QA using a multichannel approach. Phys Med 2015; 31:1035-1042. [PMID: 26429383 DOI: 10.1016/j.ejmp.2015.08.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/28/2015] [Accepted: 08/22/2015] [Indexed: 10/23/2022] Open
Abstract
PURPOSE To evaluate EBT3 for pre-treatment patient specific quality assurance (QA). The method we propose combines the experience gained in our center with the guidelines of the protocol proposed by Lewis et al. in 2012. To compare the multichannel approach with the single channel dosimetry. METHODS Gafchromic® EBT3 films were irradiated both at linac and TomoTherapy and calibration curves were obtained. A series of irradiations with simple fields (uniform dose distributions on regular shaped targets) was performed. In a second stage, films were exposed to full clinical plans at linac (step and shoot IMRT and VMAT). At TomoTherapy dose maps were obtained for a clinical plan in three different coronal planes. Films were digitized using an Epson 10000XL scanner and FilmQA™ Pro software was employed for the analysis. RESULTS The measured calibration curves suggest that, at least for the two beams taken into account (6 MV linac and TomoTherapy), a single calibration can be successfully adopted for each film lot. The application of the multichannel optimization method strongly improves the results in terms of gamma passing rates of the comparison between measured and calculated maps. CONCLUSIONS Up to now EBT films, although attractive, were not preferred for routine patient specific QA due to their complex and time consuming processing and to the challenging work of characterization. The application of the mentioned protocol, together with some additional precautions, and the adoption of the multichannel optimization dosimetry, make this detector a handy and reliable tool for patient specific QA.
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Affiliation(s)
- Livia Marrazzo
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
| | - Margherita Zani
- Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Stefania Pallotta
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Chiara Arilli
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy
| | - Marta Casati
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy
| | | | - Cinzia Talamonti
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Marta Bucciolini
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
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Perles LA, Mirkovic D, Anand A, Titt U, Mohan R. LET dependence of the response of EBT2 films in proton dosimetry modeled as a bimolecular chemical reaction. Phys Med Biol 2013; 58:8477-91. [DOI: 10.1088/0031-9155/58/23/8477] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Marrazzo L, Pallotta S, Kłosowski M, Czopyk Ł, Bucciolini M, Olko P, Waligórski M. Clinical tests of large area thermoluminescent detectors under radiotherapy beams. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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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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Park JY, Lee JW, Choi KS, Lee JS, Kim YH, Hong S, Suh TS. Development of a novel quality assurance system based on rolled-up and rolled-out radiochromic films in volumetric modulated arc therapy. Med Phys 2012; 38:6688-96. [PMID: 22149851 DOI: 10.1118/1.3659706] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a cylindrical phantom with rolled-up radiochromic films and dose analysis software in the rolled-out plane for quality assurance (QA) in volumetric modulated arc therapy (VMAT). METHODS The phantom consists of an acrylic cylindrical body wrapped with radiochromic film inserted into an outer cylindrical shell of 5 cm thickness. The rolled-up films with high spatial resolution enable detection of specific dose errors along the arc trajectory of continuously irradiated and modulated beams in VMAT. The developed dose analysis software facilitates dosimetric evaluation in the rolled-up and rolled-out planes of the film; the calculated doses on the corresponding points where the rolled-up film was placed were reconstructed into a rectangular dose matrix equivalent to that of the rolled-out plane of the film. The VMAT QA system was implemented in 3 clinical cases of prostate, nasopharynx, and pelvic metastasis. Each calculated dose on the rolled-out plane was compared with measurement values by modified gamma evaluation. Detected positions of dose disagreement on the rolled-out plane were also distinguished in cylindrical coordinates. The frequency of error occurrence and error distribution were summarized in a histogram and in an axial view of rolled-up plane to intuitively identify the corresponding positions of detected errors according to the gantry angle. RESULTS The dose matrix reconstructed from the developed VMAT QA system was used to verify the measured dose distribution along the arc trajectory. Dose discrepancies were detected on the rolled-out plane and visualized on the calculated dose matrix in cylindrical coordinates. The error histogram obtained by gamma evaluation enabled identification of the specific error frequency at each gantry angular position. The total dose error occurring on the cylindrical surface was in the range of 5%-8% for the 3 cases. CONCLUSIONS The developed system provides a practical and reliable QA method to detect dosimetric errors according to the gantry angle. Film dosimetry based on rolled-up and rolled-out techniques leads to dose verification in the subspaces of the 3D dose volume. The system can be employed as an alternative tool to detect the pitfalls of planar dose verification.
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Affiliation(s)
- Ji-Yeon Park
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
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Evaluation of a Gafchromic EBT2 film dosimetry system for radiotherapy quality assurance. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2011; 34:251-60. [DOI: 10.1007/s13246-011-0072-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
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Ebert MA, Asad AH, Siddiqui SA. Suitability of radiochromic films for dosimetry of very-low energy X-rays. J Appl Clin Med Phys 2009; 10:232-240. [PMID: 19918224 PMCID: PMC5720584 DOI: 10.1120/jacmp.v10i4.2957] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 03/11/2009] [Indexed: 11/25/2022] Open
Abstract
This study examined the response characteristics of three commercially available radiochromic films when exposed to low energy (50 kVp) X‐rays. The aim was to evaluate the films for potential use in 2D dosimetry for a low‐kV intraoperative radiotherapy (IORT) device known as the ‘Intrabeam’. Dose‐response relationships were obtained for Gafchromic EBT, XR‐RV2, and XR‐QA film in water at several distances from the Intrabeam device. It was found that the dose rates from the source were excessive for use of the XR‐QA film, and that all three film types showed significant energy dependence within the limits of measurement uncertainty. Basic modeling of primary X‐ray spectra indicated large changes in the lower energy components with distance from the source, and it is hypothesized that the changes in film response are a result of changes in film energy response. This is in contrast to previous studies indicating less or negligible energy response. All films showed non‐linearity in response over the ranges examined. These results imply significant limitations for the use of these films for low‐kV dosimetry. PACS number: 87.53.Bn
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Affiliation(s)
- Martin A Ebert
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, 6009.,School of Physics, University of Western Australia, Crawley, Western Australia, 6009
| | - Ali H Asad
- Department of Imaging and Applied Physics, Curtin University of Technology, Bentley, Western Australia, 6102
| | - Salim A Siddiqui
- Department of Imaging and Applied Physics, Curtin University of Technology, Bentley, Western Australia, 6102
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Brady SL, Toncheva G, Dewhirst MW, Yoshizumi TT. Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. HEALTH PHYSICS 2009; 97:195-205. [PMID: 19667802 PMCID: PMC3721518 DOI: 10.1097/hp.0b013e3181a9bd42] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To provide for accurate dosimetry in a 137Cs irradiator, the following were investigated: (1) correct mapping of the irradiator cavity's dose distribution, (2) rotated versus stationary dose rate measurements, (3) exposure-to-dose calibration selection for exposure time calculation, and (4) irradiator-timer error correction. This work introduces techniques to map dose distributions and measure dose rates with new high-sensitivity radiochromic films and a small-volume ion chamber constructed for in-beam, high-intensity gamma irradiation. Measured film distributions were compared to manufacturer-provided data and independent measurements from an ion chamber and TLD-100 chips. Measured film distributions agreed with the manufacturer-provided data in the central-vertical region, but disagreed by as much as 95% in surrounding regions. The independent measurements agreed within 96% with the measured dose distribution. Dose rates varied by approximately 11% for a rotational versus stationary setup, by approximately 10% for the dose-to-medium correction between air and soft tissue, and by approximately 4-12% for irradiation times from 0.2-0.7 min due to timer error. In conclusion, a critical irradiator characterization should be performed, initially, as a part of the acceptance testing of a newly installed irradiator, and periodically as an ongoing quality assurance protocol. We investigated, and recommend as part of a comprehensive irradiator verification protocol, the inclusion of radiochromic film-measured dose distributions, dose rates measured during rotation when samples are likewise rotated for exposure, timer error corrections for short-time irradiation, and exposure-to-dose corrections that reflect typical sample compositions, e.g., soft tissue or air.
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Affiliation(s)
- Samuel L Brady
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
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Schneider F, Polednik M, Wolff D, Steil V, Delana A, Wenz F, Menegotti L. Optimization of the gafchromic EBT protocol for IMRT QA. Z Med Phys 2009; 19:29-37. [PMID: 19459583 DOI: 10.1016/j.zemedi.2008.09.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Quality assurance of external beam (radio)therapy (EBT) requires tools with specific characteristics. A radiochromic film dubbed "Gafchromic EBT" (G-EBT) that is particularly suited for external beam therapy because of its features was introduced in 2004. Its characteristics, especially the high spatial resolution, make it suitable for measurement of dose distributions in radiotherapy, especially intensity-modulated radiation therapy (IMRT). While several aspects of the film characteristics have been previously reported separately, we present a comprehensive evaluation centered on practical IMRT verification, leading to an optimized protocol. Therefore the constancy within one batch, the relationship between optical density (OD) and dose (dose range between 1.4 Gy and 8.4 Gy) and the dose rate dependence for four dose rates (55, 108, 217, 441 MU/min) were investigated. In addition to these characteristics, energy dependence between two energies (50kV and 6 MV), tissue equivalency, post irradiation coloration over one month, pressure and temperature sensitivity were evaluated. We then optimized the protocol using the G-EBT films, in combination with an EPSON-Expression 1680 pro flatbed scanner, for IMRT QA, while either striving to keep the compound error as small as possible or trying to reduce evaluation time. As a basis for this protocol optimization, the characteristics of the scanner (such as inhomogeneity of the scanning field) and its software (such as consequences of extracting only the red color channel) had to be determined first. The interaction of film and scanner (variation of the OD depending on the scanning direction or the scanning resolution) was assessed as well. Using the optimized protocol for IMRT QA, the compound error could be reduced to approximately 2% for a quality-driven approach and maximum 5.5% for an approach attempting to reduce procedure time. While the quality-driven approach provides appropriate accuracy for individual patient QA, the procedure-time driven approach can only be used for preliminary measurements.
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Affiliation(s)
- Frank Schneider
- Department of Radiation Oncology of the University Medical Center Mannheim, Mannheim, Germany.
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Rink A, Lewis DF, Varma S, Vitkin IA, Jaffray DA. Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium. Med Phys 2008; 35:4545-55. [PMID: 18975701 PMCID: PMC2736758 DOI: 10.1118/1.2975483] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/18/2008] [Accepted: 08/02/2008] [Indexed: 11/07/2022] Open
Abstract
The effects of temperature on real time changes in optical density (DeltaOD) of GAFCHROMIC EBT film were investigated. The spectral peak of maximum change in absorbance (lambdamax) was shown to downshift linearly when the temperature of the film was increased from 22 to 38 degrees C. The DeltaOD values were also shown to decrease linearly with temperature, and this decrease could not be attributed to the shift in lambdamax. A compensation scheme using lambdamax and a temperature-dependent correction factor was investigated, but provided limited improvement. Part of the reason may be the fluctuations in hydration of the active component, which were found to affect both position of absorbance peaks and the sensitivity of the film. To test the effect of hydration, laminated and unlaminated films were desiccated. This shifted both the major and minor absorbance peaks in the opposite direction to the change observed with temperature. The desiccated film also exhibited reduced sensitivity to ionizing radiation. Rehydration of the desiccated films did not reverse the effects, but rather gave rise to another form of the polymer with absorbance maxima upshifted further 20 nm. Hence, the spectral characteristics and sensitivity of the film can be dependent on its history, potentially complicating both real-time and conventional radiation dosimetry.
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Affiliation(s)
- Alexandra Rink
- Princess Margaret Hospital/Ontario Cancer Institute, Department of Medical Biophysics and Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
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