SBRT focal dose intensification using an MR-Linac adaptive planning for intermediate-risk prostate cancer: An analysis of the dosimetric impact of intra-fractional organ changes

•Prostate SBRT with focal boosting to the MR visible tumor up to 45 Gy is feasible with daily adaptive planning on the MR-Linac.•Analysis of online MR imaging immediately pre and post treatment offers a unique opportunity to quantify planned and delivered dosimetry to both the targets and organs at risk (OARs).•Intrafractional bladder filling may result reduction in dose delivered to the focally boosted tumor.