ESTRO 2024 - Abstract Book

S3092

Physics - Autosegmentation

ESTRO 2024

Out of the 62 patients, 38 received photon (IMRT), and 24 received proton (IMPT) radiotherapy. 37.1% of this highly selected cohort were ultimately diagnosed with stenosis. Patients who received IMPT demonstrated a trend for lower and delayed occurrence of stenosis that was not statistically significant in this limited cohort. The calcification ratio in the selected carotid range before RT emerged as a robust indicator for post-RT stenosis. Patients with a calcification ratio exceeding 2.5% on both lateralities exhibited an 85% incidence of post-RT stenosis, whereas patients with a ratio below 2.5% reported stenosis in only 24% of cases (p = 0.001). No difference was seen comparing changes in the calcification ratio within the first post-treatment year. The mean area of the ipsilateral carotid decreased after 4 months and 1 year post-RT in 65% and 56% of patients without stenosis and in 59% and 86% of patients with stenosis, respectively (non-significant).

Figure 1: (a) The distribution of the calcification ratio calculated from simulation CT for stenosis negative and positive patients, categorized by treatment modality. (b) Kaplan-Meier plot of accumulated survival of stenosis for patients treated with IMRT and IMPT with censorship marked. Log-rank p value is 0.50.

Conclusion: