ESTRO 2024 - Abstract Book

S461

Clinical - Breast

ESTRO 2024

•In this study, planning CT images for treatment planning are acquired using fanBeam with Aquilion equipment (Canon), and CBCT images are obtained from the On Board Imager of the VersaHD LINAC (Elekta Oncology System, Crawley, UK)

•The planning CT and CBCT images are uploaded to RayStation, and image registration is performed with a focus on bone structure. Through overlay, we visually verify the quality of the registration between the planning CT and CBCT, and then generate a synthetic CT using the hybrid intensity and structure-based DIR method (ANACONDA algorithm) implemented in RayStation.

•Dose grid information is imported from the existing synthetic CT treatment plan, followed by reanalysis of the dose distribution. The DVH index is then extracted using a Matlab program.

•Extracted indicators include D 95 in the PTV low-dose and high-dose areas, Dmax of the heart, spinal cord, esophagus, and contralateral breast, and ipsilateral lung D max , D mean , V 5 , and V 10 values, and calculate the mean and the relative difference during the fractionated irradiation period to determine the change in dose.