Creating a Voxel Phantom for Dosimetric Verification of Treatment Plans in the Gamma-Knife Perfexion using the Monte Carlo Method

Abstract

   The aim of this work is to create a voxel phantom with the use of DICOM (Digital Imaging and Communications in Medicine) images for verification of dosimetric Monte Carlo calculations of the Gamma Knife Perfexion.

   The voxel phantom has been created using the Labview program, and the Monte Carlo simulation has been carried out using the Penelope / PenEasy program. To simulate the radiation transfer using Penelope, it is required to specify the number and size of voxels along the x, y, and z axes, as well as the material and density in each voxel. The data used are computed tomography files of a real patient in the DICOM format with information about the type of study, the size of pixels, and the distance between them, etc., as well as the value of pixels in Hounsfield Units (HU). To create the voxel phantom, data from DICOM images have been imported and converted into a file readable by penEasy step by step: – the first step involves importing information about the pixels to create the header of the file, – the second step is to assign materials and densities to the HU units. HU units are converted into the density, then are divided into four groups, and a material is assigned to each group for Monte Carlo simulation. To save the computational time, the image resolution of 512×512 pixels is reduced to 256 × 256 pixels by removing one HU unit of even rows and columns from the original matrix. As a first result, the voxel phantom has been created using images in the DICOM format.