Radium-223 dichloride (223RaCl2), approved by FDA (Food and Drug Administration) in 2013 and in Brazil by ANVISA (Agência Nacional de Vigilância Sanitária) in 2016, offers a new therapeutic option for bone metastases from castration-resistant prostate cancer (CRPC). The advantages of radionuclide therapy for bone metastases include the simultaneous treatment of multiple lesions at the same time. The activity prescription is based on the patient's body weight, disregarding the absorbed dose limit of 2 Gy in the organ at risk: bone marrow. This study focuses on Internal Dosimetry for 223RaCl2 therapy aiming to apply biokinetic models described in the literature to estimate absorbed doses in the organs of interests, especially for the bone marrow. For this purpose, the present paper compares and validates the GATE Monte Carlo simulation with the Radioactive Decay Module (RDM) and calculates a set of S-values for Radium-223 radionuclide using male and female XCAT computational models. Moreover, a comparison of S-values for Radium-223 for three male computational models with different anatomies is also evaluated, Male (standard), Pat1 (lower body weight) and Pat2 (highest body weight). A comprehensive set of S-values was calculated for the Male model, 30 source-regions and 47 target-regions, and for Female model, 30 source-regions and 42 target-regions for Radium-223 and its decay scheme: Radon-219, Polonium-215, Lead-211, Bismuth- 211, Polonium-211 and Thallium-207. The new set of S-values will facilitate absorbed dose calculations for Radium-223 therapy. In addition, Absorbed Dose Evaluation for 223RaCl2 therapy was estimated for three different biodistributions described in the literature within three male computational models. For all biodistributions, the Pat2 phantom has a greatest absorbed dose within the red marrow, when compared with Male and Pat1.
Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine. 2022 Aug 02 [Epub ahead of print]
Catherine C O Silva, Ademir X da Silva, Delson Braz, Luis F C Lima, W P Segars, Lidia V de Sá
Nuclear Engineering Department, Universidade Federal do Rio de Janeiro, Horácio Macedo Ave., 2030, Block G, Technology Center, University City, Fundão Island, 21941-914, Rio de Janeiro, RJ, Brazil. Electronic address: ., Nuclear Engineering Department, Universidade Federal do Rio de Janeiro, Horácio Macedo Ave., 2030, Block G, Technology Center, University City, Fundão Island, 21941-914, Rio de Janeiro, RJ, Brazil., Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, NC, USA., Institute of Radiation Protection and Dosimetry, National Nuclear Energy Commission, Salvador Allende Ave., 3773, Recreio dos Bandeirantes, 22783-127, Rio de Janeiro, RJ, Brazil.