End-to-end test for computed tomography-based high-dose-rate brachytherapy

Abstract

PurposeOne of the important developments in brachytherapy in recent years has been the clinical implementation of complex modern technical procedures. Today, 3D-imaging has become the standard procedure and it is used for contouring and precise position determination and reconstruction of used brachytherapy applicators. Treatment planning is performed on the basis of these imaging methods, followed by data transfer to the afterloading device. Therefore, checking the entire treatment chain is of high importance. In this work, we describe an end-to-end test for computed tomography (CT)-based brachytherapy with an high-dose-rate (HDR) afterloading device, which fulfills the recommendation of the German radiation-protection-commission.Material and methodsThe treatment chain consists of a SOMATOM S64 CT scanner (Siemens Medical), the treatment planning system (TPS) BrachyVision v.13.7 (VMS), which utilizes the calculation formalism TG-43 and the Acuros algorithm v. 1.5.0 (VMS) as well as GammaMedplus HDR afterloader (VMS) using an Ir-192 source. Measurement setups for common brachytherapy applicators are defined in a water phantom, and the required PMMA applicator holders are developed. These setups are scanned with the CT and the data is imported into the TPS. Computed TPS reference dose values for significant points located on the side of the applicator are compared with dose measurements performed with a PinPoint 3D chamber 31016 (PTW Freiburg).ResultsThe deviations for the end-to-end test between computed and measured values are shown to be ≤ 5%, when using an implant needle or vaginal cylinder. Furthermore, it can be demonstrated that the test procedure provides reproducible results, while repositioning the applicators without carrying out a new CT-scan.ConclusionsThe end-to-end test presented allows a practice-oriented realization for checking the whole treatment chain for HDR afterloading technique and CT-imaging. The presented phantom seems feasible for performing periodic system checks as well as to verify newly introduced brachytherapy techniques with sufficient accuracy.

The Design of an Audit Test for 60Co Brachytherapy Treatment Planning System

“…To minimize misadministration, an appropriate audit and QA need to be introduced and guarantee the accuracy of BT treatment. [ 10 11 12 13 14 15 16 17 ]…”

The dosimetric impact of replacing the TG-43 algorithm by model based dose calculation for liver brachytherapy

“…MBDC of current interest for 192 Ir brachytherapy include collapsed-cone point kernel superposition [11][12][13], gridbased Boltzmann solvers [14,15] as well as reference Monte Carlo (MC) simulation [16]. Different treatment planning systems (TPS) have adopted some of the algorithms listed above [13,17]. In the context of 192 Ir high dose rate (HDR) brachytherapy, the use of MBDC is particularly important for treatment sites in the vicinity of tissue/air or tissue/lung interfaces, and wherever variations of tissue density play an important role [1].…”