Variation of optimization techniques for high dose rate brachytherapy in cervical cancer treatment

Abstract

High dose rate (HDR) brachytherapy treatment planning usually involves optimization methods to deliver uniform dose to the target volume and minimize dose to the healthy tissues. Four optimizations were used to evaluate the high-risk clinical target volume (HRCTV) coverage and organ at risk (OAR). Dose-volume histogram (DVH) and dosimetric parameters were analyzed and evaluated. Better coverage was achieved with PGO (mean CI = 0.95), but there were no significant mean CI differences than GrO (p = 0.03322). Mean EQD2 doses to HRCTV (D90) were also superior for PGO with no significant mean EQD2 doses than GrO (p = 0.9410). The mean EQD2 doses to bladder, rectum, and sigmoid were significantly higher for NO plan than PO, GrO, and PGO. PO significantly reduced the mean EQD2 doses to bladder, rectum, and sigmoid but compromising the conformity index to HRCTV. PGO was superior in conformity index (CI) and mean EQD2 doses to HRCTV compared with the GrO plan but not statistically significant. The mean EQD2 doses to the rectum by PGO plan slightly exceeded the limit from ABS recommendation (mean EQD2 dose = 78.08 Gy EQD2). However, PGO can shorten the treatment planning process without compromising the CI and keeping the OARs dose below the tolerance limit.

Keywords

• Brachytherapy
• 3-D
• Treatment planning
• Cervix cancer
• Optimization techniques