Work

Impact of rectal gas evacuation on dosimetry and applicator displacement in cervical cancer brachytherapy

Year: 2026

Type: article

Abstract: Objective This study aimed to evaluate the impact of rectal gas evacuation on organ‐at‐risk (OAR) volumes, dose‐volume histogram (DVH) parameters, and applicator displacement during cervical cancer brachytherapy. Methods Twenty‐one cervical cancer patients who received three‐dimensional brachytherapy at our center between November and December 2024 and presented with rectal gas were retrospectively included. Planning computed tomography (CT) images were acquired before and after rectal gas evacuation to evaluate changes in rectal and bladder volumes, as well as radiation dose variations to OARs (bladder, rectum, sigmoid, and small intestine). Dosimetric parameters analyzed comprised D 0.1cc , D 1cc , D 2cc , and D 5cc (minimum doses delivered to the most irradiated 0.1, 1, 2, and 5 cm 3 of the OARs, respectively), as well as D max (maximum dose) and D mean (mean dose). Displacements of the applicator tip and cervical stopper were quantified using a coordinate system based on pelvic bony landmarks. Results Rectal volume decreased by 40.1% after gas evacuation, while bladder volume increased by 18.2%. D 0.1cc , D 1cc , D 2cc , D 5cc , and D max in the rectum decreased significantly ( P < 0.001) after gas evacuation, whereas no significant changes were observed in the DVH parameters of the other OARs. The mean displacements of the applicator tip and cervical stopper were 5.86 ± 3.64 mm and 4.23 ± 3.30 mm, respectively. Conclusions Rectal gas evacuation results in a statistically significant and clinically relevant reduction in rectal volume and rectal dose, underscoring its importance as a routine clinical procedure. However, as it may induce millimeter‐level applicator displacement with clinically measurable dosimetric consequences, careful monitoring is warranted, with post‐evacuation replanning or, if necessary, applicator adjustment.

Source: Journal of Applied Clinical Medical Physics

DOI: 10.1002/acm2.70490

Authors: Haiyan Wu, Chengdian he, Mei Liu, Xiujuan Zhao

Institutions: Chongqing University, Chongqing Cancer Hospital

Language: English

Topic: Advanced Radiotherapy Techniques

Subfield: Radiation

Field: Physics and Astronomy

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $900