82. IBU and CT based conformal HDR brachytherapy

Abstract

The aim of the study is to present advantages of IBU and CT based panning in conformal brachytherapy (BT).

Applicator localization and dose planning in modern BT can be achieved by an integrated BT Unit (IBU) and CT based planning. Due to online connection between the localizer and the planning system, ihe fluoroscopy images are imported directly for reconstroction purpose, resulting in dose distribution view in operating room after dose calculation. That enables – if necessary – optimisation of the dose distribution by optimisation of the implant geometry. Fluoroscopy images can be easily stored to database, and used for verification during next fractions. The disadvantage of IBU based planning is that there is no possibility to enter volumes of interest itito treatment plan. The localization of the applicator during fluoroscopy is analysed mostly due to well seen bony structures.

In order to add information concerning also soft tissue during planning procedure, CT examination of patient with implaced applicator is performed followed by all volume of interest definition.

The dose distribution calculated on the base of IBU and CT images are comparable, however CT- based planning visualizes dose distribution in all selected volumes of interest (f.e. in critical organs, PTV etc). Verification of the applicator localization by IBU is an easy, reproducible method however the localization of the applicator in relation to surrounding tissues is possible only in CT-based option.