ESTRO 2024 - Abstract Book

S3344

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

The accuracy of the 3D detector localization within the spot pattern was determined in a controlled setup, where the three detectors were placed with submillimetre accuracy in the water bath without mice.

Results:

The 3D-accuracy of the detector localisation methods was <0.5mm. The in vivo data showed a 2mm mouse-to-mouse variation in the (X,Y)-position. Hence all 126 mice were placed similarly inside the dose field. There was a general trend that the mice placed in the left side of the field were at a shallower depth, while the ones in the right side of the field were at a deeper depth, indicating a 0.8-degree misalignment of the water bath relative to the beam direction. This misalignment led to six mice in the right side of the field being placed on the slope of the spread-out Bragg peak rather than at the distal edge. This was also reflected by the measured dose, where these six mice received less dose than planned fig. 2B.