Abstract
BACKGROUND: Previous studies have evaluated nodal dose using Point-A prescriptions or variable dose rates. However, the impact of volume-based high-dose-rate (HDR) brachytherapy approaches remains less explored. In this study, we aimed to assess the dose contribution to the pelvic lymph nodes with volume-based (HR-CTV) prescription in comparison to point-A-based prescription during HDR brachytherapy in carcinoma cervix. This comparison has not been comprehensively evaluated in earlier literature, especially in the context of elective nodal contouring and HDR brachytherapy. MATERIALS AND METHODS: Thirty patients with carcinoma of the cervix [International Federation of Gynecology and Obstetrics (FIGO) stage IB2 or higher] were included for this retrospective study. Two plans were generated on each brachytherapy scan. The first plan (point-A-based) prescribed a dose of 7 Gy to point-A, while the second plan (HR-CTV-based) prescribed the dose to the HR-CTV. Dose volume histograms (DVH) parameters were compared between both the plans. RESULTS: HR-CTV-based plans registered safer doses to OARs. Both the plans showed noticeable dose contributions to the pelvic lymph node stations, particularly the obturator, internal iliac, and presacral stations, with the highest contribution observed in the obturator group. However, HR-CTV-based plans contributed lower doses to these nodal regions, approximately 1 Gy less to the internal iliac and obturator stations and 2 Gy less to the presacral station compared to point-A-based plans when D50 was considered. CONCLUSIONS: HR-CTV-based plans demonstrated recognizable dose contribution to lymph nodes, although lower than the contribution by point-A-based plans. However, this modest difference can be effectively compensated by optimizing the external beam radiotherapy (EBRT) dose while simultaneously maintaining safe organ at risk (OAR) doses.