A feasibility study of hyoscine butylbromide (buscopan) to improve image quality of cone beam computed tomography during abdominal/pelvic Stereotactic Ablative Radiotherapy.

Objectives: Cone beam computed tomography (CBCT) is used for image guidance of stereotactic ablative radiotherapy (SABR), but it is susceptible to bowel motion artefacts. This trial evaluated the impact of hyoscine butylbromide (buscopan) on CBCT image quality and its feasibility within a radiotherapy workflow.

Methods: A single-centre feasibility trial (ISRCTN24362767) was performed in patients treated with SABR for abdominal/pelvic oligorecurrence. Buscopan was administered to separate cohorts by intramuscular (IM) or intravenous (i.v.) injection on alternate fractions, providing within-patient control data. 4-point Likert scales were used to assess overall image quality (ranging from excellent to impossible to use) and bowel motion artefact (ranging from none to severe). Feasibility was determined by patient/radiographer questionnaires and toxicity assessment. Descriptive statistics are presented.

Results: 16 patients were treated (8 by IM and 8 by i.v. buscopan). The percentage of images of excellent quality with/without buscopan was 47  29% for IM buscopan and 65  40% for i.v. buscopan. The percentage of images with no bowel motion artefact with/without buscopan was 24.6  8.9% for IM buscopan and 25.8  7% for i.v. buscopan. Four patients (25%) reported dry mouth. 14 patients (93%) would accept buscopan as routine. 11 radiographers (92%) reported no delay in treatments.

Conclusions: A trend towards improved image quality/reduced bowel motion artefact was observed with IM/i.v. buscopan. Buscopan was well tolerated with limited impact on workflow.

Advances In Knowledge: This is the first trial of buscopan within a radiotherapy workflow. It demonstrated a trend to improved image quality and feasibility of use.