Paramedical Sciences and Military Health

Introduction: One of the problems that exists in the quality control procedure of the treatment planning systems and the computer simulation of the radiotherapy or diagnostic radiology validation is comparing the dose distribution resulted from the dose calculation algorithms with the experimental results(as a reference). For this purpose, several methods have been proposed to compare these dose distributions and determine the amount of the similarity or differences quantitatively. The dose difference (DD), distance to agreement (DTA) or the combination of these two parameters named gamma evaluation and these methods are the common methods for this purpose. Ignoring the factors related to the irradiation and disallowing the differences between the different regions in the dose distribution are the most important problems of these methods. The aim of this study is to providing a novel method which is able to consider mentioned factors and differences during the comparison procedure.   

Materials and Methods: According to previous studies, 4 different regions and 3 different irradiation conditions was defined for the dose distribution and irradiation mode respectively. Special restrictions in the DD and DTA were considered for each couple of the region-irradiation condition. In each region of dose distribution gamma evaluation equations was defined according to these restrictions and dose comparison was performed as region to region in all regions of the dose distribution.

Results: Weighted gamma evaluation algorithm was obtained and proposed table related to the DD and DTA restrictions was written.  

Discussion and conclusion: Due to the related and relevant equations for any region of the dose distribution in the weighted gamma evaluation method, it is expected that this method will show a clinically better results compared to the common methods.