TY - JOUR
T1 - On dosimetric characteristics of detectors for relative dosimetry in small fields
T2 - a multicenter experimental study
AU - Casar, Božidar
AU - Mendez, Ignasi
AU - Gershkevitsh, Eduard
AU - Wegener, Sonja
AU - Jaffray, David
AU - Heaton, Robert
AU - Pesznyak, Csilla
AU - Stelczer, Gabor
AU - Bulski, Wojciech
AU - Chełminski, Krzysztof
AU - Smirnov, Georgiy
AU - Antipina, Natalia
AU - Beavis, Andrew W.
AU - Harding, Nicholas
AU - Jurković, Slaven
AU - Hwang, Min Sig
AU - Saiful Huq, M.
N1 - Publisher Copyright:
© 2024 The Author(s). Published on behalf of Institute of Physics and Engineering in Medicine by IOP Publishing Ltd.
PY - 2024/2/7
Y1 - 2024/2/7
N2 - Objective. In this multicentric collaborative study, we aimed to verify whether the selected radiation detectors satisfy the requirements of TRS-483 Code of Practice for relative small field dosimetry in megavoltage photon beams used in radiotherapy, by investigating four dosimetric characteristics. Furthermore, we intended to analyze and complement the recommendations given in TRS-483. Approach. Short-term stability, dose linearity, dose-rate dependence, and leakage were determined for 17 models of detectors considered suitable for small field dosimetry. Altogether, 47 detectors were used in this study across ten institutions. Photon beams with 6 and 10 MV, with and without flattening filters, generated by Elekta Versa HDTM or Varian TrueBeamTM linear accelerators, were used. Main results. The tolerance level of 0.1% for stability was fulfilled by 70% of the data points. For the determination of dose linearity, two methods were considered. Results from the use of a stricter method show that the guideline of 0.1% for dose linearity is not attainable for most of the detectors used in the study. Following the second approach (squared Pearson’s correlation coefficient r 2), it was found that 100% of the data fulfill the criteria r 2 > 0.999 (0.1% guideline for tolerance). Less than 50% of all data points satisfied the published tolerance of 0.1% for dose-rate dependence. Almost all data points (98.2%) satisfied the 0.1% criterion for leakage. Significance. For short-term stability (repeatability), it was found that the 0.1% guideline could not be met. Therefore, a less rigorous criterion of 0.25% is proposed. For dose linearity, our recommendation is to adopt a simple and clear methodology and to define an achievable tolerance based on the experimental data. For dose-rate dependence, a realistic criterion of 1% is proposed instead of the present 0.1%. Agreement was found with published guidelines for background signal (leakage).
AB - Objective. In this multicentric collaborative study, we aimed to verify whether the selected radiation detectors satisfy the requirements of TRS-483 Code of Practice for relative small field dosimetry in megavoltage photon beams used in radiotherapy, by investigating four dosimetric characteristics. Furthermore, we intended to analyze and complement the recommendations given in TRS-483. Approach. Short-term stability, dose linearity, dose-rate dependence, and leakage were determined for 17 models of detectors considered suitable for small field dosimetry. Altogether, 47 detectors were used in this study across ten institutions. Photon beams with 6 and 10 MV, with and without flattening filters, generated by Elekta Versa HDTM or Varian TrueBeamTM linear accelerators, were used. Main results. The tolerance level of 0.1% for stability was fulfilled by 70% of the data points. For the determination of dose linearity, two methods were considered. Results from the use of a stricter method show that the guideline of 0.1% for dose linearity is not attainable for most of the detectors used in the study. Following the second approach (squared Pearson’s correlation coefficient r 2), it was found that 100% of the data fulfill the criteria r 2 > 0.999 (0.1% guideline for tolerance). Less than 50% of all data points satisfied the published tolerance of 0.1% for dose-rate dependence. Almost all data points (98.2%) satisfied the 0.1% criterion for leakage. Significance. For short-term stability (repeatability), it was found that the 0.1% guideline could not be met. Therefore, a less rigorous criterion of 0.25% is proposed. For dose linearity, our recommendation is to adopt a simple and clear methodology and to define an achievable tolerance based on the experimental data. For dose-rate dependence, a realistic criterion of 1% is proposed instead of the present 0.1%. Agreement was found with published guidelines for background signal (leakage).
KW - characteristics
KW - detectors
KW - relative dosimetry
KW - small fields
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U2 - 10.1088/1361-6560/ad154c
DO - 10.1088/1361-6560/ad154c
M3 - Article
C2 - 38091616
AN - SCOPUS:85183317552
SN - 0031-9155
VL - 69
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 3
M1 - 035009
ER -