WE‐E‐BRB‐04: Quantitative Dose Tracking Enabled Through a Novel Deformable 3D Dosimeter

Purpose: To evaluate and investigate the feasibility of a new method for validating dose tracking algorithms in deforming tissues using a novel deformable 3D dosimeter. Methods: A novel deformable 3D Presage dosimeter is reported consisting of a stretchy polyurethane matrix doped with radiochromic leuco‐dye. Two deformable cylindrical dosimeters (6 cm diameter, 5 cm long) were manufactured and irradiated with a checkerboard arrangement of 5 mm square pencil beams created by MLC fields. One dosimeter was irradiated under lateral compression by 33% (6 cm down to 4 cm diameter) to simulate a deformed organ. A second control dosimeter was irradiated with the same checkerboard pattern but without deformation applied. High‐resolution 3D dose distributions (isotropic 1 mm resolution) were obtained by optical‐CT imaging. Physical dose deformation was quantified by comparing checkerboard pencil beam shapes and positions in the deformed and control dosimeters. Results: Deformation of dose in the deformed dosimeter was clearly visible in all 3 dimensions. The deformed checkerboard dose pattern showed expansion of 16% – 46% along the axis of compression, with higher expansion observed in the central regions of the dosimeter. Perpendicular to the compression axis, the dose pattern contracted by 7% – 13%. Peak dose changes of −6% and +30% were observed parallel and perpendicular to the compression axis respectively. Dose response was linear from 0–8 Gy. Conclusions: Dose tracking was successfully quantified in a novel deforming 3D dosimeter. This capability has potential as a powerful new method for validating deformable dose tracking and registration algorithms.