Avaliação das doses ocupacionais e médicas e do risco de câncer em procedimentos cardíacos de radiologia intervencionista utilizando método Monte Carlo

• Autor(a) principal: Santos, William de Souza
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/handle/riufs/5295
• topic: Física médica; Método de Monte Carlo; Radiologia; Pessoal da área médica; Saúde e trabalho; Radiação; Radiação - Dosimetria; Raios X; Ecocardiografia; Simuladores antropomórficos; Medical personnel; Medical physics; Monte Carlo method; Radiation; Radiation dosimetry; Radiology; X-rays; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA

Cardiac procedures are the most common within the interventional radiology (IR) and they can provide high medical and occupational exposures, since, in most cases these procedures are time consuming and complexes. Although the use of X-rays is justified in this case, it is important to make an assessment of radiation doses and associated risk to patients and medical staff. The aim of this study was to build a computational model of exposure composed of an adult patient, a cardiologist and a nurse, in a typical cardiac scenario in IR and, then, estimate absorbed doses in organs and tissues, and through this dosimetric quantity, determine equivalent doses, the effective dose and cancer risk associated with exposure. The estimated dosimetric quantities were normalized by the kerma-area product (KAP). In this study, the results are presented in conversion coefficient (CC) for radiation dose and cancer risk. The radiographic parameters used in the Monte Carlo simulations were: peak voltages between 60 and 120 kVp, inherent filtration of 3.5 mm Al and a field area 10 cm x 10 cm. Eight beam projections were used: antero-posterior (AP), postero-anterior (PA), right anterior oblique (RAO90o), left anterior oblique (LAO90o), cranial (CRAN30o), caudal (CAUD30o), left anterior oblique and right anterior oblique (LAO45o and RAO45o). The radiation transport code used was MCNPX 2.7.0, in which was incorporated three anthropomorphic phantoms were incorporated with a source of X-rays emitting photons isotropically in the patient´s chest region and all common objects inside the room in IR. The anthropomorphic phantoms used to represent the cardiologist and the patient were the MASH and the nurse was simulated by the FASH phantom. Energy spectra were generated using the SRS 78 program. Two irradiation scenarios named I and II were created. In I, the operating table had no lead curtain and suspended shields of lead glass and, in II, these protection devices were considered. The average effective dose of CCs for the eight projections used in cardiac procedures angiography and coronary angioplasty was: patient 2,5E-01 mSv/Gy.cm2; cardiologist 2,0E-01(I) and 4,7E-02 ÊSv/Gy.cm2 (II) and nurse 2,4E-02 (I) and 1,8E-02 ÊSv/Gy.cm2 (II).The effective risk of cancer in 10-4/Gy.cm 2 was: 1.2 for the patient, 2,6 E-03 (I) and 4.9 E-04 (II) for the cardiologist and 5.2 E-04 (I) and 4.0 E-04 (II) for the nurse. The results presented in this study are consistent with the experimental values obtained in the literature. Thus, we believe that results improve or extend the existing data and will be a useful reference tool for professionals of radiation protection, the scientific community and especially for the physicians themselves who are exposed routinely.