고선량률 근접치료계획의 정도보증 프로그램

Abstract

Purpose: The planning of High-Dose-Rate(HDR) brachytherapy treatments are becoming individualized and more dependent on the treatment planning system. Therefore, computer software has been developed to perform independent point dose calculations with the integration of an isodose distribution curve display into the patient anatomy images. Materials and Methods: As primary input data, the program takes patients’ planning data including the source dwell positions, dwell times and the doses at reference points, computed by an HDR treatment planning system (TPS). Dosimetric calculations were performed in a 10×12×10 cm³ grid space using the interstitial Collaborative Working Group (ICWG) formalism and an anisotropy table for the HDR Iridium-192 source. The computed doses at the reference points were automatically compared with the relevant results of the TPS. The MR and simulation film images were then imported and the isodose distributions on the axial, sagittal and coronal planes intersecting the point selected by a user were superimposed on the imported images and then displayed. The accuracy of the software was tasted in three benchmark plans performed by Gamma-Med 12i TPS (MDS Nordion, Germany). Nine patients’ plans generated by Plato (Nucletron Corporation, The Netherlands) were verified by the developed software. Results: The absolute doses computed by the developed software agreed with the commercial TPS results within an accuracy of 2.8% in the benchmark plans. The isodose distribution plots showed excellent agreements with the exception of the tip region of the source’s longitudinal axis where a slight deviation was observed. In clinical plans, the secondary dose calculations had, on average, about a 3.4% deviation from the TPS plans. Conclusion: The accurated validation of complicate treatment plans is possible with the developed software and the quality of the HDR treatment plan can be improved with the isodose display intergrated into the patient anatomy information.