Cone Beam CT-guided Online Adaptive Radiotherapy for Prostate Stereotactic Body Radiation Therapy.

Abstract

PurposeWhile CT-guided online adaptive radiotherapy (CTgART) is an emerging treatment modality for prostate stereotactic body radiotherapy (SBRT), the feasibility and dosimetric improvements have not yet been quantified in a large multi-center cohort.MethodsA cohort of 74 prostate cancer patients treated with a 5-fraction SBRT course of CTgART between 01/2023-06/2024 was collected from two centers and analyzed retrospectively. Timestamps of the adaptive process and the daily contoured volumes were collected in addition to the dose volume histogram (DVH) data for both the scheduled and adapted plans. The duration of the adaptive process and pre-treatment verification imaging shift magnitudes were compared. Differences in DVH metrics between the scheduled and adapted plans were analyzed.ResultsThe adapted plan was chosen in 95% of all fractions, with 81% of patients having all 5 fractions adapted. The mean adaptive planning time was 18.7 ± 4.8 minutes (mean ± standard deviation). The mean shift in each cardinal direction was ConclusionsCTgART for SBRT treatment of prostate cancer can be done in a timely and reproducible manner while substantially improving the dosimetry of target coverage and OAR sparing.