Methodological development and clinical application of volumetric dosimetry (3D) for the radionuclide therapy of thyroid cancer and other tumors

• Grant number: 14/50091-5
• Support Opportunities: Research Grants - Research in Public Policies for the National Health Care System (PP-SUS)
• Start date: July 01, 2014
• End date: December 31, 2015
• Field of knowledge: Health Sciences - Medicine - Medical Radiology
• Agreement: CNPq - PPSUS
• Principal Investigator: Marcelo Tatit Sapienza
• Grantee: Marcelo Tatit Sapienza
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Radionuclide therapy is recognized as a medical procedure for over 70 years. Among the procedures of the Brazilian Health System is represented mainly by radioactive iodine treatment of hyperthyroidism and thyroid carcinoma. The activity of radionuclides used for therapeutic purposes is often determined empirically. The internal dosimetry can be used for radionuclide therapy, planning, through the measurement of radiation doses that lead to deterministic biological effects such as cell death. These doses should be determined for each patient, in order to produce a therapeutic effect in tumor and reduced toxicity to healthy tissues. Therefore, the dosimetric calculation parameters used in therapy should mirror biodistribution, kinetics, morphology and geometry of the patient; preferably obtained in tridimensional imaging methods such as SPECT or PET/CT. Objective: To develop and apply a method of three-dimensional dosimetry based on SPECT and PET/CT imaging, seeking to incorporate the internal dosimetry in planning radionuclide therapy of tumors. Method: 1) development of volumetric dosimetric calculation model, with the acquisition of serial images of a phantom using PET/CT and SPECT/CT, parameter optimization for image pre-processing, aiming the composition of a parametric image of absorbed dose, 2) validation of the dosimetric method developed, considering as reference the MIRD-Olinda/EXM dosimetric method, 3) retrospective application of the dosimetric method on anonymised patients, 4) prospective clinical application of the dosimetric method and construction of a database for future correlation between absorbed dose and effects of radiation. (AU)