Um modelo para dosimetria celular baseada em imagem óssea de micro-CT para terapia com dicloreto de rádio-223

Abstract

Cell-level dosimetry in the bone marrow for alpha particles is a challenge mainly due to the complexity of the trabecular structure. This work presents a cellular dosimetry model to radium-223 dichloride therapy using GATE simulations and a mouse bone structure realistically described by a microCT image. Simulations considered the radionuclide chain of radium-223. The region of interest was the radiosensitive skeletal tissues. Skeletal segmentation was performed by the automatic and non-supervised Fuzzy C-Means. The simulation parameters were validated by comparing the absorbed fraction values in a known model. The update of the endosteal thickness suggests that models should be used following the ICRP 110. Most cells receive no absorbed dose above 2 Gy. The dose distribution in the medullary cavity by the known model was reproducible in mice. Beta emissions increase the toxic potential in cells near the bone surface. The absorbed dose accumulated in the cell is in the order of Gray’s magnitude more by the amount of interacting particles than by the magnitude of the energy deposited individually by the particles. The model was feasible to implement updates of ICRP 110, can be extended to other bone sites and can be adjusted to other radionuclides that are bone markers, giving way to new studies of cellular dosimetry.