ESTRO 2025 - Abstract Book

S2596

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

Measured profiles are shown in Fig. 1, DORs, ROFs and profile FWHM are shown in Table 1. The 8mm MSB DORs were within 0.5% of the ROFs calculated using the microdiamond detector, film and planning system. The 4mm MSB DORs were within 3% of the ROFs calculated using planning system and film, and microdiamond. Uncertainties on these measurements were greatest for radiochromic film (5.2% for 4mm) smallest for the micro diamond (0.6% for 4mm) with the MSBs in-between (3.6% for 4mm). Film ROFs with significant variation were seen throughout the literature [1,3,5]. FWHM calculated using MSB-measured profiles were within 0.5mm of those measured by film, planning system and others [1,2]. The use of onboard imaging to position the beads was essential for DOR measurement accuracy and reproducibility. The use of MSBs was limited to z-axis measurements due to the design of the solid water phantom.

Conclusion: The MSBs provided satisfactory measurements of DORs and shot profiles and can serve as a lower cost and more efficient method of dosimetry.