The impact of intra-fractional bladder filling on “Plan of the day” adaptive bladder radiotherapy

A retrospective audit on the “Plan of the day” (POD) selection and intra-fractional bladder fillings were carried out on twenty adaptive bladder radiotherapy patients at a single institution. Treatment time, differences in bladder volume and displacement of outer bladder wall expansion over the treatment fraction were analysed. Average treatment time was 8.9 min. The mean percentage difference in bladder volume pre and post treatment was 13.7%, resulting in expansion of the bladder predominately in the superior and anterior directions. This audit confirmed that the institution’s POD process sufficed without being significantly affected by the intra-fractional bladder filings.