ESTRO meets Asia 2024 - Abstract Book

S287

Interdisciplinary – Urology

ESTRO meets Asia 2024

anatomy (D delivered,i ). Dose accumulation of all 5 fractions was applied by registering the MRI adapt scans at fractions 2 – 5 to that of fraction 1, resulting in a D ACC,planned . Similarly the MRI during scans were used to generate D ACC,delivered (Figure 1).

Figure 1: Schematic overview of the dose accumulation pipeline that was used to reconstruct the accumulated dose for the GTV and CTV.

Results:

OARs constraints were met in all plans of all patients. In the plans for the artificial GTVs, representing T3b tumors, the near minimum dose to the GTV (D98% ACC, planned ), which correlates most strongly with outcome, showed a median of 41.3 Gy (40.1 Gy – 43.0 Gy) compared to 43.7 Gy (40.3 Gy – 47.5 Gy) in the clinical plans for patients without seminal vesicle invasion. The D ACC, delivered to the GTV, taking into account intra-fraction motion, showed a median D98% of 41.1 Gy (38.9 Gy – 42.6 Gy) in the plans for artificial GTVs compared to 43.0 Gy (40.2 Gy – 46.7 Gy) in the clinical plans (Figure 2).

Figure 2: Boxplots of the accumulated planned (solid) and delivered (dashed) D98% to the GTV for the clinical treatment plans of patients without seminal vesicle invasion (T2-T3a) (blue) and simulated treatments plans of patients with seminal vesicle invasion (T3b) (green).

Conclusion: