ESTRO 2025 - Abstract Book

S4034

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

Results: Our results showed a significant increase in the nodes and beams for Plan with_arm by an average of 18.38% and 5.81%, respectively. The result indicated the increased spatial freedom for optimal beam placement. Max MU per beam significantly decreased by 0.93% as expected. For the plan quality metrics, a reduced value of D max,PTV by 0.74% was observed while no significant change in D mean,PTV , D min,PTV , D 90%,PTV and D 95%,PTV in Plan with_arm . Conformity index (CI) and homogeneity index (HI) also decreased. This implied an increase in dose heterogeneity within the target for Plan with_arm , which was desirable for SBRT plans. For the dose falloff outside the PTV, a decreased value of D max,2cm was observed for Plan with_arm . This implied a faster dose falloff. For dose-volume constraints, D max,Spinal Cord , D mean,Spinal Cord , D mean,Heart , D max,Esophagus , and D mean,Esophagus for Plan with_arm decreased significantly. Plan with_arm resulted in unavoidable doses to the arms. However, acute or late toxicity to the arms would be rare at the dose levels reported in this study.