Dosimetric impact of intrarectal gas removal by Foley catheter on image-guided adaptive brachytherapy in cervical cancer patients.

PURPOSE: Intraluminal gas in rectum can be observed in some cervical cancer patients who underwent brachytherapy, leading to increased rectal volume. This might increase radiation dose to the rectum, and result in rectal complications. The aim of the study was to investigate the effect of intrarectal gas drainage by rectal catheterization using Foley catheter on rectal dimensions, target dose, and adjacent organs at risk (OARs) doses in cervical cancer patients treated with image-guided adaptive brachytherapy.

MATERIAL AND

METHODS

Computed tomography (CT) images before and after rectal gas drainage were retrospectively collected from 20 brachytherapy sessions of 17 cervical cancer patients, who received image-guided adaptive brachytherapy from January 2018 to May 2019 at a single institution. Target volume and adjacent OARs were delineated, and brachytherapy planning was performed using both CT images. Rectal diameter from 2 cm above to 2 cm below cervical os were measured. Dosimetric comparison between pre-procedural and post-procedural plans was performed.

RESULTS

Rectal medio-lateral diameter at multiple levels was significantly decreased after rectal gas drainage, while rectal antero-posterior diameter only at 1 cm above cervical os was significantly decreased after the procedure. The calculated dose to high-risk clinical target volume (HR-CTV) and the bladder dose was comparable before and after the procedure. However, significant reductions in rectal D0.1cc (5.52 ±0.92 Gy vs. 4.82 ±0.93 Gy, p = 0.009), D1cc (4.04 ±0.58 Gy vs. 3.67 ±0.76 Gy, p = 0.006), and D2cc (3.67 ±0.55 Gy vs. 3.34 ±0.72, p = 0.004) were observed after the procedure.

CONCLUSIONS

Intrarectal gas reduction by rectal catheterization with Foley catheter can significantly reduce rectal distention in lateral dimension and improve rectal dosimetric parameters. This procedure can be used in patients with remaining intraluminal rectal gas after patient rectal self-preparation to minimize rectal toxicity.