ESTRO 2021 Abstract Book

S1428

ESTRO 2021

Conclusion The automated plan QA tool flagged clinically unacceptable treatment plans and indicated regions of potential improvement in the majority of the VMAT test plans similar to the ROs (in 7/12 plans). The proposed QA tool demonstrates the potential to automatically support the treatment planning process. PO-1701 Effects of atelectasis changes on geometric and dosimetric in tumor and lung tissue for lung cancer H. Chen 1 , Z. Xu 2 1 shanghai chest hospital, Radiation Oncology, Shanghai, China; 2 Shanghai chest hospital, Radiation Oncology, Shanghai, China Purpose or Objective 270 CBCT scans of 18 lung patients with atelectasis were collected every other day, to record the fraction and degree of resolution or expansion of atelectasis, and analyze the geometry changes including the center of mass(COM), boundary and volume of the tumor, and volume of ipsilateral lung. Dosimetric changes in the target and lung tissue were also quantified. Materials and Methods 270 CBCT scans of 18 patients with atelectasis were collected every other day, to record the fraction and