ESTRO 2024 - Abstract Book

S6010

RTT - Treatment planning, OAR and target definitions

ESTRO 2024

A total of 205 patients entered the TORPEdO trial, with 136 (66%) allocated to IMPT and 69 (34%) to IMRT. Complete radiotherapy CRF replan information was available for 194/205 (132 IMPT and 65 IMRT) patients. Ninety-three (48%) of these patients did not require a replan while 101 (52%) (81 IMPT and 20 IMRT) were replanned at least once during the treatment course (table 1). A significantly increased replanning rate was observed in the IMPT arm compared to the IMRT arm (p<0.001). Most (77%) replanning was performed at the week 3 dosimetric review, 60/81 IMPT and 18/20 IMRT cases (Figure 1). There were 4 cases that stated additional reason for replanning due to increased dose to airway or to OARs which were not included in the pre-defined criteria (Figure 1). Five IMPT patients required replanning prior to the week 3 dosimetric review. In four cases this was due to inadequate target coverage. Replanning occurred after the week 3 dosimetric review in 17/101 patients who required a replan (15 IMPT and 2 IMRT) due to inadequate target coverage and dosage to critical structures being greater than 2% tolerance. For 14 patients (13 IMPT and 1 IMRT), 2 replans were required, and for 1 patient treated with IMPT 3 replans were conducted. Across the trial, a total of 116 replans (95 IMPT and 21 IMRT) were performed.

Conclusion: