Significance of 60 Co high-dose-rate three-dimensional brachytherapy in treatment of pediatric vaginal rhabdomyosarcoma / 中华放射肿瘤学杂志

ABSTRACT

Objective To explore the treatment procedure of pediatric vaginal rhabdomyosarcoma ( RMS) using 60 Co high?dose?rate three?dimensional ( 3D ) brachytherapy, and to analyze its dosimetric feasibility. Methods Computed tomography ( CT ) images were collected from five children undergoing radiotherapy for vaginal RMS. Three treatment plans were designed:plan A using 3D conformal radiotherapy with external beam irradiation, plan B using brachytherapy, and plan C using brachytherapy combined with external beam irradiation. Dosimetric parameters for clinical target volume ( CTV ) and organs at risk ( OARs ) were evaluated based on EQD 2 and analyzed using one ? way analysis of variance . Results Compared with plan A, plan C had significantly larger D90, D50, and Dmean for CTV ( all P=0?00), significantly lower doses to the rectum, bladder, and femoral head, and a significantly higher dose to the ovary ( all P=0?00) . Compared with plan B, plan C had a larger D90 for CTV, smaller D50 and Dmean for CTV, a lower dose to the ovary, and higher doses to the rectum, bladder, and femoral head. Among the three plans, plan B had the smallest D2 cm3 for the rectum and bladder. Conclusions The optimal radiotherapy plan for pediatric vaginal RMS should be based on the primary tumor location and residual tumor after surgery. CT image?guided 60 Co high?dose?rate 3D brachytherapy is convenient, effective, and well tolerated by children. It also achieves a high dose to CTV as well as good protection of normal tissue.