A Dosimetric Comparison of Two Techniques of Brachytherapy in Carcinoma Cervix in Patients with a Difficult Application

Abstract

To compare dosimetrically the coverage of clinical target volume (CTV) and doses to organs at risk (OAR) between intracavitary brachytherapy (ICBT) and interstitital brachyhterapy (ISBT) in patients of carcinoma cervix with narrow vaginal apex. Between December 2017 and September 2019, 27 patients of carcinoma cervix stages IB–IIIB aged between 41 and 65 years, who had complete response or persistent disease limited to medial third of parametria post-external beam radiotherapy (EBRT) with narrow vaginal apical anatomy, and those who could accommodate only semi-small ovoids (smallest size ovoids for the applicator), were included in the study. ICBT followed by ISBT a week later was performed for the same patient. For similar volumes, target coverage and doses to OAR were compared for the two techniques. For similar volumes in both techniques, the D90 and V90 were comparable. Mean dose to 2 cc bladder, rectum, and sigmoid for ICBT was 4.76 Gy, 4.12 Gy, and 2.61 Gy, respectively, and the corresponding values for ISBT were 3.84 Gy, 4.06 Gy, and 1.63 Gy significantly favoring ISBT. In various stages of cancer cervix, post-EBRT for patients with a complete response or persistent disease limited to medial third of parametria with narrow vaginal apex, ISBT remains the treatment of choice compared to ICBT by significantly reducing the doses to the OARs.