ESTRO 2024 - Abstract Book

S3218

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Both measurements ( 1600 SRS - Pinpoint) where compared to study the liquid chamber influence with the field size.

Results:

Figure 1 summarizes the influence of the selection of the field size used in the calibration of the plan. A difference of 2-3 % in the calibration factor is obtained for a field size of 2x2 cm 2 with respect to that used routinely (4x4cm 2 ). These differences are accentuated for the 1x1 cm2 field, obtaining deviations of 9-10 % for flattering filter free beams and of the order of 7% for flattening filter beams. For field sizes larger than 6x6cm2 the differences in calibration factors are less than 1%. The differences obtained between the Pinpoint detector and the liquid chamber array measurements were attributed to the dependence of the detector array response on the energy spectrum and dose per pulse.

Figure 2 shows the difference in the measurement obtained in the verification of two treatments when calibrating the detector with a 4x4 cm 2 field and a 2x2 cm 2 field for an energy of 10FFF.