Biocerâmicas com 166Ho e 153Sm: síntese, caracterização e avaliação dosimétrica em Radiovertebroplastia

Abstract

Due to the high incidence of spinal metastases in cancer patients there are deep concerns about new therapies that improve quality of life. Regardless the advances in the treatment of such disease, the outcomes concerning pain relief and tumor control are not often durable and effective. Radiovertebroplasty emerges as the possibility of combining vertebroplasty with radiation therapy through the injection of a radioactive bone cement into the vertebral body. Such minimally invasive procedure will provide local tumor control, pain reduction and spine stabilization, thus improving patient quality of life. Considering the terapeutic potencial of radiovertebroplasty, this study involved the synthesis and characterization of bioceramics of holmium and samarium incorporated calcium orthophosphates in order to develop a radioactive bone cement; and also the performation of computational dosimetry within a vertebrae phantom for radiovertebroplasty with 166Ho. The synthesis was prepared using a simple sol-gel route that produced mainly bioactive phases as -tricalcium phosphate and hydroxyapatite, and also holmium and samarium phosphates. The estimated activity after activation in IPR1/CDTN research reactor was 32,5 MBq.mg-1 for bioceramic with 166Ho, and 14,5 MBq.mg-1 for bioceramic with 153Sm. The Monte Carlo dosimetry showed that radiovertebroplasty with 166Ho provides terapeutical doses at the lesion site while spinal cord only receives less than 10% of the dose . Comparing to the others radiotherapy protocols, radiovertebroplasty with 166Ho should provide better local tumor control and smaller incidence of late damage on spinal cord. The results suggest that radiovertebroplasty with 166Ho is safe and effective for spinal mestastases treatment, and the bioceramics with Ho and Sm can be used to compose the radioactive bone cement. Nonetheless, only the clinical trials can establish the real benefits, risks and indications of this new therapeutic procedure.