Computational dosimetry evaluation in vertebral models using a radioactive bone cement with Sm-153, Ho-166 and Y-90

Abstract

─ Background: Breast cancer is a disease that affects a large part of the Brazilian female population. Especially, those bones metastasis developed in the spinal column. This can produce potential fractures with neurological compromise or reduction of the life's quality of the patient due to chronic pain. Objective: Computational dosimetry study in vertebrae models simulating bone metastasis locating a radioactive bone cement with Sm-153, Ho-166 or Y-90 in the vertebral body. Methods: Radiological images of animal vertebrae was used to construct a model using the MCNPx code (MonteCarlo N-Particle code). Deposited doses were evaluated in the axial plane (XY) respect to implant of the radioactive bone cement into the metastasis. The nearest organ of risk (OAR) was the spinal cord and the planning target volume (PTV) was the implant itself on the vertebrae. The and Yttrium-90 (Y-90) radionuclides were considered. Results: The therapeutic deposited dose obtained in the implant plane by radioactive bone cement reaches levels above 70 Gy for specific activities close to 3 GBq•mg -1 with suitable values for the Y-90 coupled to the cement. Exposure to Ho-166 produces a dose such that cover 76,49 % and 62,77 % for two cases with metastasis respect to PTV while Y-90 covers 94,30 % and 80,91 % on the PTV. Conclusions: The radioactive cement implant may potentially to make an optimal tumor control and lower side effects in organs at risk.