[Dose Distribution Optimization in Combined Intracavitary and Interstitial Brachytherapy for Cervical Cancer]

Hybrid inverse treatment planning optimization (HIPO) is a new optimization tool for brachytherapy. We verified its utility using treatment plans for combined intracavitary and interstitial brachytherapy in cervical cancer.

We compared the manually optimized plan and the plan optimized using HIPO. The plan using HIPO was optimized with three different methods: needle only, tandem and needle, and all applicators. The dose volume histogram (DVH) parameters such as D₉₀ of high risk clinical target volume (HR-CTV) and D_2cc of OAR (rectum, sigmoid colon and bladder) were used to evaluate each treatment plan.

The D₉₀ of HR-CTV in most plans was received more than 600 cGy. In addition, the D_2cc of OAR also was less than the tolerance dose on the average of all plans. However, the D_2cc of the rectum and bladder treatment plans optimized only with needles was significantly higher than other plans.

The treatment plans used in clinical practice and obtained by HIPO have similar dose distributions and DVH parameters. Moreover, the time needed to create treatment plan was reducing by HIPO. We suggest that HIPO will be an effective tool in treatment planning.