TY - JOUR
T1 - Performance of the HYPERSCINT scintillation dosimetry research platform for the 1.5 T MR-linac
AU - Uijtewaal, Prescilla
AU - Côté, Benjamin
AU - Foppen, Thomas
AU - de Vries, Wilfred
AU - Woodings, Simon
AU - Borman, Pim
AU - Lambert-Girard, Simon
AU - Therriault-Proulx, François
AU - Raaymakers, Bas
AU - Fast, Martin
N1 - Funding Information:
Prescilla Uijtewaal and Martin Fast acknowledge funding by the Dutch Research Council (NWO) through Project No. 17515 (BREATHE EASY). We acknowledge research agreements with MedScint (Quebec, Canada) and with Elekta AB (Stockholm, Sweden).
Publisher Copyright:
© 2023 The Author(s). Published on behalf of Institute of Physics and Engineering in Medicine by IOP Publishing Ltd.
PY - 2023/2/21
Y1 - 2023/2/21
N2 - Objective. Adaptive radiotherapy techniques available on the MR-linac, such as daily plan adaptation, gating, and dynamic tracking, require versatile dosimetric detectors to validate end-to-end workflows. Plastic scintillator detectors (PSDs) offer great potential with features including: water equivalency, MRI-compatibility, and time-resolved dose measurements. Here, we characterize the performance of the HYPERSCINT RP-200 PSD (MedScint, Quebec, CA) in a 1.5 T MR-linac, and we demonstrate its suitability for dosimetry, including in a moving target. Approach. Standard techniques of detector testing were performed using a Beamscan water tank (PTW, Freiburg, DE) and compared to microDiamond (PTW, Freiburg, DE) readings. Orientation dependency was tested using the same phantom. An RW3 solid water phantom was used to evaluate detector consistency, dose linearity, and dose rate dependence. To determine the sensitivity to motion and to MRI scanning, the Quasar MRI4D phantom (Modus, London, ON) was used statically or with sinusoidal motion (A = 10 mm, T = 4 s) to compare PSD and Semiflex ionization chamber (PTW, Freiburg, DE) readings. Conformal beams from gantry 0° and 90° were used as well as a 15-beam 8 × 7.5 Gy lung IMRT plan. Main results. Measured profiles, PDD curves and field-size dependence were consistent with the microDiamond readings with differences well within our clinical tolerances. The angular dependence gave variations up to 0.8% when not irradiating directly from behind the scintillation point. Experiments revealed excellent detector consistency between repeated measurements (SD = 0.06%), near-perfect dose linearity (R 2 = 1) and a dose rate dependence <0.3%. Dosimetric effects of MRI scanning (≤0.3%) and motion (≤1.3%) were minimal. Measurements were consistent with the Semiflex (differences ≤1%), and with the treatment planning system with differences of 0.8% and 0.4%, with and without motion. Significance. This study demonstrates the suitability of the HYPERSCINT PSD for accurate time-resolved dosimetry measurements in the 1.5 T MR-linac, including during MR scanning and target motion.
AB - Objective. Adaptive radiotherapy techniques available on the MR-linac, such as daily plan adaptation, gating, and dynamic tracking, require versatile dosimetric detectors to validate end-to-end workflows. Plastic scintillator detectors (PSDs) offer great potential with features including: water equivalency, MRI-compatibility, and time-resolved dose measurements. Here, we characterize the performance of the HYPERSCINT RP-200 PSD (MedScint, Quebec, CA) in a 1.5 T MR-linac, and we demonstrate its suitability for dosimetry, including in a moving target. Approach. Standard techniques of detector testing were performed using a Beamscan water tank (PTW, Freiburg, DE) and compared to microDiamond (PTW, Freiburg, DE) readings. Orientation dependency was tested using the same phantom. An RW3 solid water phantom was used to evaluate detector consistency, dose linearity, and dose rate dependence. To determine the sensitivity to motion and to MRI scanning, the Quasar MRI4D phantom (Modus, London, ON) was used statically or with sinusoidal motion (A = 10 mm, T = 4 s) to compare PSD and Semiflex ionization chamber (PTW, Freiburg, DE) readings. Conformal beams from gantry 0° and 90° were used as well as a 15-beam 8 × 7.5 Gy lung IMRT plan. Main results. Measured profiles, PDD curves and field-size dependence were consistent with the microDiamond readings with differences well within our clinical tolerances. The angular dependence gave variations up to 0.8% when not irradiating directly from behind the scintillation point. Experiments revealed excellent detector consistency between repeated measurements (SD = 0.06%), near-perfect dose linearity (R 2 = 1) and a dose rate dependence <0.3%. Dosimetric effects of MRI scanning (≤0.3%) and motion (≤1.3%) were minimal. Measurements were consistent with the Semiflex (differences ≤1%), and with the treatment planning system with differences of 0.8% and 0.4%, with and without motion. Significance. This study demonstrates the suitability of the HYPERSCINT PSD for accurate time-resolved dosimetry measurements in the 1.5 T MR-linac, including during MR scanning and target motion.
KW - HYPERSCINT scintillation dosimetry
KW - MRI-linac
KW - Plastic scintillator detector
KW - Radiotherapy
UR - http://www.scopus.com/inward/record.url?scp=85147895041&partnerID=8YFLogxK
U2 - 10.1088/1361-6560/acb30c
DO - 10.1088/1361-6560/acb30c
M3 - Article
C2 - 36638536
AN - SCOPUS:85147895041
SN - 0031-9155
VL - 68
SP - 1
EP - 11
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 4
M1 - 04NT01
ER -