ESTRO 2024 - Abstract Book

S5526

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

MRI, bilateral artificial hip implants and prior prostatectomy. Patients were consented under the PRIMER imaging study (6) and educated on the hydration guidelines (Figure 1).

Each participant attended three scanning sessions on the MRL. One at the beginning, middle and end of their treatment course. Patients were asked to follow the hydration guidelines during their course of radiotherapy and at least two days prior to, and the day of each scanning session. Patients prepared for their radiotherapy treatment as per standard protocol. To help achieve this, MRL scans were performed two hours before patient’s treatment time. T2 weighted MR images were acquired periodically over 40 minutes at 0-, 15-, 25- and 35-minutes interval. The 25 minutes and 35 minutes were chosen to represent the time between initial session MRI, verification MRI and commencement of treatment delivery. Bladder fill rate 0-25 and 0-35 minutes was calculated. At each session, patients were asked to complete an experience questionnaire composed of four specific bladder filling questions. Questions were scored one to ten where 1= very uncomfortable and 10= no discomfort. Bladder volumes were contoured on all T2w images acquired. The absolute bladder volumes and change in bladder volume between timepoints were measured. The images were fused by rigidly registering the prostate, and the displacement was recorded.

Results:

Nine patients were recruited. The median (range) bladder volume was 218 cm 3 (89-363 cm 3 ) and 236 cm 3 (116-459 cm 3 ) at the 25-minutes and 35-minutes timepoint respectively. A median bladder fill rate of 1.96 cm 3 was observed