Impact of ultrasound-guided brachytherapy on optimizing planning outcomes and target volume definition in cervical cancer.

Background: Combined external beam radiotherapy (EBRT) and intracavitary brachytherapy (ICBT) are the standard treatments for cancer cervix. 3D-based image-guided brachytherapy has changed the face of intracavitary applications and allowed better dosimetric outcomes. While magnetic resonance imaging (MRI)-based therapy is the current standard, computed tomography (CT) with ultrasound measurements could represent an acceptable alternative with less cost and real-time imaging advantage. Material and methods: Our study included sixty-four patients with uterine cervix cancer (stages IB to IVA) who underwent concurrent chemoradiotherapy (CCRT), followed by high dose rate (HDR)-ICBT 8 GY/FR/weekly. Patients were randomized into two arms: Arm A (application done ultrasound-guided with each fraction in 32 cases) and Arm B (without image guidance). The rate of optimal insertion is defined as tandem centralized within the uterine cavity without perforation; the needle insertion rate is also calculated between both arms. Results: Ultrasound guidance significantly improved the rate of optimal insertion and reduced the rate of uterine perforation by 12% (from 14.6% to 1.8%). Optimal insertion positively impacted isodose distribution, resulting in numerically higher Dmax values for organs at risk (OARs) in the non-ultrasound-guided group. However, it was not statistically significant. On the other hand, MRI and US measurements were found to be comparable, with the largest mean difference being 2.3 mm, which is not found to be clinically significant. Conclusion: The use of ultrasound is strongly recommended during brachytherapy as it minimizes the rate of suboptimal insertions. Also, US measurement strongly correlated with MRI, which may support its use in a radiotherapy setting with a lack of MRI availability.