Effectiveness of abdominal compression in reducing internal target motion during conformal radiotherapy for carcinoma...

: To assess the effectiveness of abdominal compression in reducing internal target motion during conformal radiotherapy for stomach cancer.

A pilot study was conducted on five patients who received adjuvant radiotherapy for stomach cancer. All the patients had surgical clips and were offered radiotherapy and concurrent chemotherapy as per the institutional protocol. An abdominal compression device was developed consisting of a triangular Styrofoam's plate and an inflatable air bladder that was positioned over the patients' abdomen. The pneumatic pressure was set according to the patients' comfort. On the simulation day, patients had two computed tomography (CT)-scanning sessions, with and without abdominal compression. Target volumes and organs at risk (OAR) were delineated on the CT images without compression. On the treatment day, fluoroscopy was acquired with onboard imager (OBI) and movements of surgical clips with and without compression analyzed with the help of a tracker software. Observed values with and without abdominal compression were compared.

Abdominal compression usage has reduced the mean breathing excursion (MBE) in medio lateral(ML) direction from 5.92mm to 4.15 mm and in cranio caudal direction (CC) from 11.3mm to 7.2mm. The range of reduction by 29.85% in the ML and 36.86% in CC direction. The average residual breathing excursion was 1.766 mm (SD = 1.33 mm) in the ML and 4.02 mm (SD = 2.18 mm) in the CC direction, respectively.

Abdominal compression was useful in reducing internal target motion during stomach cancer conformal radiotherapy. The device we developed is patient friendly and cost-effective.