Evaluation of RayStation's delivered dose and accumulated dose features for spine stereotactic radiotherapy

We investigated delivered dose and dose accumulation features in the dose tracking module of RayStation version 11B before potential integration into the spine stereotactic radiosurgery (SSRS) program at our institution. End-to-end testing with a rigid Rando phantom was performed, and 10 retrospective clinical cases were selected for evaluation. Pre-treatment cone beam CTs (pCBCT) were corrected for Hounsfield unit (HU) integrity and contours were rigidly copied from the reference plan. We then calculated the delivered dose to the corrected cone beam CT (cCBCT). A deformable image registration (DIR) was generated between cCBCT and reference planning CT (rCT) using controlling region of interests. Deformed delivered dose to the rCT was summed to generate the accumulated dose for multiple fractions. The end-to-end tests of the phantom study revealed an improvement of cCBCT HU information by > 100 HU compared to the pCBCT. When compared to the reference plan, the delivered dose and deformed delivered dose were within 1.0% for the GTV and CTV and 3.0% for the spinal cord, respectively. Nearly all 10 clinical cases demonstrated delivered dose and accumulated dose deviations < 3.0% from the reference plan. However, 2 patients rendered delivered dose deviations between 3.0% and 4.0%, showing the effectiveness of the module. The dose tracking module in RayStation version 11B could potentially be utilized to aid clinical decision-making for external body shape change or positional deviation in SSRS for rigid target and critical structures. Evaluation before clinical application under one's specific practice is required, and results must be carefully analyzed specially near the high dose gradient area.