ESTRO 2024 - Abstract Book

S4324

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

Table 1: Evaluation criteria for PTV margin evaluation.

Evaluation score

Criteria

Rejected

CTV not covered by PTV in >1 transversal slice

CTV borderline to PTV in > 1 transversal slice and/or CTV not covered by PTV in 1 transversal slice

Inconclusive

Approved

CTV in all transversal slices covered by PTV

Results:

For prostate the RTTs approved a 4 mm margin in 95% of the fractions, while 2% of the fractions were rejected (Figure 1). For a 3 mm margin, 57% of the fractions were approved, while 5% were rejected. The scoring from the two RTTs was consistent; e.g., for 3 mm, one RTT approved 58% of the fractions, while the other approved 55%. If the couch was moved less than 2 mm in any direction, 70% of the fractions were approved for a 3 mm margin, compared to 32% for shifts greater than 2 mm (Figure 2). The analysis of the cervix treatment will be presented when the results are analysed.

Figure 1: Scoring of prostate treatment fractions (color-coded) with respectively 3, 4 and 5 mm PTV margin by RTT1 (a) and RTT2 (b).