ESTRO 2023 - Abstract Book

S822

Monday 15 May 2023

ESTRO 2023

Conclusion We have developed and implemented VMAT-TMI in our clinic (Raystation-Mosaiq environment), thereby expanding the radiotherapy options in the multidisciplinary management of patients with hematologic malignancies. PD-0974 Initial report of prospective feasibility study for modified track Dynamic WaveArc therapy Y. Ono 1 , Y. Iizuka 1 , K. Nakamura 1 , T. Ono 1 , N. Mukumoto 1 , M. Yoshimura 1 , Y. Matsuo 1 , T. Mizowaki 1 1 Kyoto University Hospital, Department of Radiation Oncology, Kyoto City, Japan Purpose or Objective Vero4DRT enables Dynamic WaveArc (DWA) by continuous gantry rotation and O-ring skewing with a moving dynamic multi leaf collimator without couch rotation (Figure). In previous work, our team identified a dosimetric advantage of novel volumetric modulated arc therapy (VMAT) featuring continuously varying non-coplanar trajectories, the DWA therapy for accelerated partial breast irradiation (APBI) and stereotactic body radiotherapy (SBRT) for spinal metastases. The upgraded treatment planning system allowed free editing of the DWA trajectories. This ‘modified track DWA’ has now been implemented, which enabled DWA therapy for APBI and spinal metastases on the actual device. We then performed a prospective study of this modified track DWA for APBI and spinal metastases. This report aimed to evaluate the feasibility of DWA therapy and acute adverse event rate.

Materials and Methods A prospective feasibility study of APBI and spinal SBRT with DWA was conducted in our single institution from 2020 to 2022, following approval by our Institutional Ethical Review Board (jRCT1052200034). Patients with stage I–II breast cancer or spinal metastases without any other lesions outside the spine were eligible (Table). For APBI, the customised trajectory was set up to avoid collision and angles that would directly irradiate the heart and left anterior descending artery. In the cervical and upper lumbar spine, the trajectories were set to avoid the shoulders and kidneys, respectively. Prescribed