ESTRO 2025 - Abstract Book

S4221

RTT - Education, training, advanced practice and role developments

ESTRO 2025

ROs compared with the RO-STAPLE (Figure 1) and MDA was 0.88±0.03 mm for RTTs and 0.75±0.05 mm for ROs. Qualitatively, the mean GTV 5-point Likert scores were 4.8 for RTTs and 4.7 for ROs. Mean change in PTV D95 coverage versus RO-STAPLE was 0.5±1.5% for RTTs and -0.7±1.9% for ROs (p <0.001, Figure 2) exhibited a statistically significant but not clinically significant difference. OARs assessed had high DICE and MDA scores for both RTTs and ROs. Dosimetric results for the OAR D0.5cc of showed a mean of –1.1±5.9% for RTTs and -1.1±12.0% for ROs (p = 0.4).

Conclusion: Our results demonstrated that an RTT-led contour adaptation workflow maintains clinically acceptable geometric and dosimetric performance comparable to RO contour edits for plan adaptation. An RTT-led MR-guided online adaptive oligometastatic disease workflow is feasible with potential to decrease the resource burden for this valuable technique and improve access to MR-guided radiotherapy techniques.

Keywords: MR-Guided Adaptive RT, Therapist-Driven, Oligomets