ESTRO 2024 - Abstract Book

S4107

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

Rectum

D 1cc

-0.08 ± 0.23

Table 1. The differences in the average accumulated dose and their standard deviations.

Differences in accumulated mean dose to the PTV were >1Gy in 14 patients, 13 of which received >1Gy less for the emulated ATP workflow compared to ATS. For CTV, there were differences >1Gy in 7 patients, with 6 being underdosed by >1Gy for the ATP workflow. The difference in accumulated mean doses for the bladder were <5Gy across the dataset. However, the rectum’s mean dose differed by >5Gy in 26 patients, and >10Gy in 8 patients, with one patient having a dose increase of 19.5Gy for the emulated ATP workflow. Mean absolute rectum volume change across patients with a ≤5Gy difference was 19.3(17.5) cc. For patients with a difference of >5Gy more to the rectum, mean change was 22.6(18.2) cc and for >10Gy more, 20.8(25.18) cc. Absolute accumulated mean dose difference and structure volume change shows a slight but non-significant positive correlation, reflected in the Pearson correlation coefficient for bladder (r =0.16, p=0.20) and rectum (r =0.18, p=0.16) (Figure 2(c) and (d)).