ESTRO 2023 - Abstract Book

S1602

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ESTRO 2023

Results All plans fulfilled the clinical CTV goal (Table 1). The nominal plan_3 took an additional minute to plan compared to the nominal plan_1 and plan_2 since it required input of function weights from them. There was no time difference in adaptive planning, however. The mean OAR dose in plan_3 was either the lowest or comparable to the minimum of plan_1 or plan_2. Plan_1 and plan_2 reduced the OAR dose differently depending on the OAR’s volume variation over the fractions (Figure 1). The max EUD function in plan_1 typically worked better than the dose gradient function in plan_2 in the case where the OAR volume in vCT was smaller compared to pCT and vice-versa. Overall, plan_3 resulted in lower mean doses regardless of OAR volume changes. It should be noted that the CTV V98% in plan_3 was reduced to achieve 95% dose coverage in the OAR overlap region with the intended objective of toxicity reduction since the overlapping region of OAR and CTV changed daily.

Conclusion