Influence of magnetic field on a novel scintillation dosimeter in a 1.5 T MR-linac

J Appl Clin Med Phys. 2023 Nov 27:e14180. doi: 10.1002/acm2.14180. Online ahead of print.ABSTRACTFor commissioning and quality assurance for adaptive workflows on the MR-linac, a dosimeter which can measure time-resolved dose during MR image acquisition is desired. The Blue Physics model 10 scintillation dosimeter is potentially an ideal detector for such measurements. However, some detectors can be influenced by the magnetic field of the MR-linac. To assess the calibration methods and magnetic field dependency of the Blue Physics scintillator in the 1.5 T MR-linac. Several calibration methods were assessed for robustness. Detector characteristics and the influence of the calibration methods were assessed based on dose reproducibility, dose linearity, dose rate dependency, relative output factor (ROF), percentage depth dose profile, axial rotation and the radial detector orientation with respect to the magnetic field. The potential application of time-resolved dynamic dose measurements during MRI acquisition was assessed. A variation of calibration factors was observed for different calibration methods. Dose reproducibility, dose linearity and dose rate stability were all found to be within tolerance and were not significantly affected by different calibration methods. Measurements with the detector showed good correspondence with reference chambers. The ROF and radial orientation dependence measurements were influenced by the calibration method used. Axial detector dependenc...

Source: Journal of Applied Clinical Medical Physics - November 27, 2023 Category: Physics Authors: Stijn Oolbekkink Bram van Asselen Simon J Woodings Jochem W H Wolthaus J H Wilfred de Vries Adriaan A van Appeldoorn Marcos Feijoo Madelon van den Dobbelsteen Bas W Raaymakers Source Type: research