IDAC star -a standalone program to easy create Monte Carlo voxel simulated customized dose estimations

Objectives With the introduction of voxelized standard reference phantoms in nuclear medicine there is now a possibility to perform more realistic dose estimations. A computer program was developed to facilitate the process of creating customized source regions using the ICRP/ICRU adult reference voxel phantoms. This will enable to calculate dose estimations of actual treatments like an extravasation a locally administered activity. The purpose of the program is to create a user friendly graphical interface that creates a functional MCNP input file, runs the simulation and extract the results back into the program. This allows users with no experience to be able to perform voxelized Monte Carlo simulations with MCNP.

Methods IDAC star is an executable standalone Matlab program with all components incorporated into one file. The program shows both the male and female voxel phantoms graphically, where the user can draw source voxels in each slice by hand, just by clicking on the specific voxel or include spheres with arbitrary radius to create the source regions. The simulations can be made for monoenergetic alpha particles, electrons, photon decays or the predefined radionuclides I-131, Tc-99m and F-18. The program requires an MCNP version 5 or 6/6.11 to be installed. IDAC star executes and runs the MCNP program and stops after reaching a user-defined cut-off time or particle limit. After the run, the absorbed doses are presented in a table together with the relative error of each estimated dose.,the results can be saved to either an excel sheet or to an ASCII file.

Results The program was tested at hospitals to estimate the effective dose for patients where extravasation has occurred. The runtime of the simulation varies from a couple of hours to days, depending on the source location and the accuracy needed for the dose estimations. The program allows an arbitrary number of source regions, the only limitation is the assumption that there is a uniform source distribution among all selected voxel sources.

Conclusions A program was developed to allow users to easily create situation specific dose calculations without MCNP experience of both absorbed dose and effective dose on voxel phantoms. To position activity into specific voxels gives an opportunity to create more realistic dose calculations.

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