DOSIS: A novel toolkit for patient-specific internal dosimetry

K. SJÖGREEN GLEISNER; M. LJUNGBERG; F. BOTTA; M. VALENTE; P. PÉREZ; J. GUSTAFSSON

Córdoba

Simposio; 14 International Symposium on Radiation Physics; 2018

Radionuclide therapy is a valuable alternative for the treatment of systemic malignancies, which is based on radionuclides' administration to the patient using radiolabelled molecules for tumor targeting. Proper and accurate personalized dosimetry should be a relevant pre-requisite in order to achieve the required lethal damage to tumor cells while maintaining possible side-effects to normal tissues at tolerable levels.Radionuclide therapies require to assess in vivo radiopharmaceutical distribution for further estimation of absorbed dose released to target and involved organs. In this context, the DOSIS (Dosimetry Optimization System and Integrated Software) toolkit represents a valuable option to perform patient-specific dosimetry directly based on patient anatomy and patient biodistribution of radiolabelled molecule both obtained by currently available dual PET/CT or SPECT/CT techniques.This work is focused on comparing 3D dose distributions obtained with DOSIS (full stochastic Monte Carlo simulation) versus the same distributions obtained with analytic approaches (dose point kernel convolution and local energy deposition), when considering non-homogeneous activity or density distributions at different scales. Virtual phantoms were used for this purpose. The β- emitters most commonly used for therapy (90Y, 131I, 177Lu) were investigated, and emissions of β--particles, conversion electrons, gamma radiation, and characteristic X-rays were included.DOSIS implements a novel code devoted to manage radiation transport simulation by means of PENELOPE Monte Carlo general-purpose code on voxelized geometries defined by 3D mass and activity distributions. Both distributions can be defined through medical dual images, or pre-defined virtual phantoms.The obtained results confirmed DOSIS as a reliable and accurate tool for personalized internal dosimetry along with highlighting advantages/drawbacks of the different calculation schemes proposed.