Dosimetric comparison of vaginal vault ovoid brachytherapy versus intensity-modulated radiation therapy plans in postoperative patients of cervical carcinoma following whole pelvic radiotherapy.

Abstract

Dosimetric study to compare high dose rate (HDR) vaginal vault ovoid brachytherapy plan versus intensity-modulated radiation therapy (IMRT) boost plan for doses delivered to target volume and organs at risk (OAR) in postoperative patients of cervical carcinoma following whole pelvic radiotherapy (WPRT). Fifteen postoperative patients of cervical carcinoma suitable for vaginal ovoid brachytherapy following WPRT of 46 Gy/23 fractions/4.5 weeks were included. All were treated with brachytherapy (two sessions of 8.5 Gy each). The equivalent dose for IMRT was calculated by computing biologically effective dose of brachytherapy by linear quadratic model. Dose of brachytherapy (two sessions of 8.5 Gy) was equivalent to IMRT dose of 26 Gy/13 fractions. Doses to target volume and OAR were compared between HDR and IMRT plans. Target volume was well covered with both HDR and IMRT plans, but dose with brachytherapy was much higher (P < 0.05). Mean doses, doses to 0.1, 1, 2, and 5cc, 1/3 (rd) , 1/2, and 2/3 (rd) volume of bladder and rectum were significantly lower with HDR plans. In postoperative patients of cervical carcinoma, HDR brachytherapy following WPRT appears to be better than IMRT for tumor coverage and reducing dose to critical organs.