Ultrasound for image-guided brachytherapy in cervical cancer: Geometric accuracy and dosimetric evidence compared...

Cervical cancer is the fourth most common cancer worldwide, with the highest burden in low- and middle-income countries (LMICs). Image-guided brachytherapy (IGBT) with magnetic resonance imaging (MRI) is the gold standard, but access is limited in many regions. Ultrasound (US), being portable and cost-effective, has been proposed as an alternative to three-dimensional (3D) imaging with MRI or computed tomography (CT). This study systematically reviews and meta-analyzes evidence comparing US with MRI and CT in cervical cancer brachytherapy.

A systematic search (2000-2025) was conducted in PubMed, Science Direct, EBSCOhost, Cochrane Library, and Wiley (PROSPERO: CRD420251121697). Nineteen studies (n = 5-295 patients) were included, comprising prospective, retrospective, and pilot designs. Outcomes included tumor and organ-at-risk (OAR) dimensions, dosimetry, and reproducibility. Random-effects meta-analyses were performed, with heterogeneity assessed using I², and sensitivity and subgroup analyses conducted.

Across geometric parameters (height, width, thickness, volume), pooled analyses demonstrated no significant differences between US and 3D imaging, except for a small reduction in tumor thickness favoring US that was not sustained in sensitivity analyses. Dosimetric parameters, including target coverage (D90) and OAR doses (D2cc bladder, rectum, sigmoid), also showed no significant differences. Reproducibility analyses using coefficient of variation demonstrated comparable consistency between modalities.

Ultrasound yields geometric and dosimetric outcomes broadly comparable to MRI and CT, with added benefits of affordability, portability, and workflow integration. These findings support US as a feasible and reliable alternative for IGBT, particularly in LMICs, pending standardization of imaging protocols and prospective validation.