A graphical user interface for internal dose calculations

Objectives Our objective was to design a comprehensive toolkit for a variety of internal dose calculation approaches that would keep all aspects of dose calculation within the framework of a single software environment.

Methods Our MATLAB-based graphical user interface (GUI) can be used for processing data obtained using pure planar, pure SPECT, or hybrid planar/SPECT imaging. Time-activity (TA) data for regions of interest (ROIs) are obtained using a set of tools that allow us to load images, to co-register a series of planar images and to perform 2D and 3D image segmentation. Curve fits are applied to the acquired TA data to construct TA curves, which are then integrated to obtain time-integrated activity coefficients for ROIs. Subsequently, dose estimates are made using one of three methods. The ‘Organ level dose calculation’ sub-GUI calculates mean organ doses that are equivalent to dose assessment performed by OLINDA/EXM. Voxelized dose calculation options, which include the voxel S value (VSV) approach and Monte Carlo (MC) simulation using the EGSnrc user code DOSXYZnrc, are available within the ‘Process 3D image data’ sub-GUI. Using our program, dose calculations were performed with each of the three available dosimetry methods for six patients injected with Tc-99m labelled HYNIC-TOC and imaged using a hybrid planar/SPECT approach.

Results Our GUI proved to be powerful and easy to use. Mean organ doses from the ‘Organ level dose calculation’ sub-GUI and using the VSV approach agreed with MC within 6% and 8%, respectively. A comparison of the voxelized dose distributions calculated for each patient with VSV and MC found the minimum dose delivered to 90% of the target volumes to agree within 3% using the two methods.

Conclusions The developed internal dosimetry toolkit provides an assortment of tools for every step in the dose calculation process, eliminating the need for manual data transfer between programs. This saves times and minimizes user errors, while offering a versatility that can be used to efficiently perform patient-specific internal dose calculations in a variety of clinical situations.