ESTRO 2024 - Abstract Book

S2567

Clinical - Urology

ESTRO 2024

between the averaged CBCT data versus the planning CT was + 0.3 cc (± 76.3 cc). Correlations between V18.1 Gy (%) and V37 Gy (cc) for both the planning CT data and the averaged CBCT data with acute and late GU toxicities were weak with all coefficients of determination < 0.1 (Fig. 2).

Conclusion:

Among patients treated with SABR for high-risk prostate cancer, DVCs calculated from averaged pre-fraction CBCT datasets appeared to have stronger correlations with acute and late GI toxicity grades, compared to the same DVCs calculated from the planning CT, particularly for higher dose regions. These data suggest that CBCT datasets may be a better predictor of GI toxicity among this patient cohort. Consideration should be given to adopting an adaptive, personalised approach to prostate radiotherapy, particularly given the move towards fewer fractions. It is important to note, however, that correlations were weak and not statistically significant. Further research, therefore, is warranted using a larger sample size to validate these findings.

Keywords: Stereotactic, inter-fraction motion, toxicity