Evaluation of voxel based biological and physical dose volume histograms for radiotherapy treatment plan a future strategy

Abstract

Radiotherapy plan evaluation is an essential part before approval of any patient treatment undergoing radiotherapy. The present DVH based radiotherapy plan evaluation is not sufficient because it lacks the spatial information of dose distribution inside the irradiated volume. In this research work, two different approaches are used, first approach solely used the 3D data obtained from the TPS in the DICOMRT format and the second approach used the DVH ASCII le data to evaluate the radiotherapy plans. A MATLAB based VRb display tool is developed and utilized for the Voxel based BED and EQD2 plan evaluation methodology which takes into the account the different fractionation schemes and radiosensitivity of the different tissues and also offers different priority modes of PTV, CTV and OARs (a new of its own kind) for the radiotherapy plan evaluation. The problem of summation of doses from two different radiotherapy treatment plans is addressed in this research work and a solution is also proposed with some assumptions. Fractionation correction strategies are developed which use hybrid radiobiological models to evaluate and allow addition of two doses from two plans having different fractionation schedules. A new methodology has been developed to evaluate the robust radiotherapy plans through the DVH bands. These DVH bands use a collection of DVH which are generated from the TPS by simulating different uncertainties in the dose distributions. These uncertainties are associated with patient setup errors or CT numbers or the range of the particles. DVH Analyzer program is developed to process the DVH bands and provide the quantitative analysis of the uncertainties with respect to the different simulated uncertainties by using various dosimetric and radiobiological parameters. The tools developed under this research work will be helpful for the physicians and medical physicist for evaluation of various radiotherapy treatment plans. newline