Avaliação das doses de cães submetidos a exames radiográficos de pulmão

This study aims to determine surface skin doses in dogs (with suspected pulmonary metastasis) submitted to chest X-rays using the technique of thermoluminescence dosimetry. Twenty seven exams from different dogs were performed at the Faculdade de Medicina Veterinária e Zootecnia da Universidade Estadual Paulista (FMVZ-UNESP/Botucatu). The doses were evaluated using thermoluminescent dosimeters of calcium sulphate doped with dysprosium (CaSO4:Dy) produced by the Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN). The pulmonary metastasis exams are carried out in three projections, one dorsal-ventral and two lateral-lateral. During the procedures the projection thicknesses and source-skin surface distances were registered. To simulate the dog phantom the dosimeters were positioned in a cubic simulator (30x30x30 cm) of polymethylmethacrylate (PMMA) filled with water and irradiated according to the parameters of projections with the X-ray energies ranging from 45 to 70 kV. To estimate the surface skin dose the dose-response curves were obtained for X-ray energies of 50 and 70 kV using the diagnostic X-ray beam machine of the Instruments Calibration Laboratory of IPEN for doses of 1.5, 2.0, 2.5, 3.5 and 4.0 mGy. The main difficulty of this work was the dog immobilization that is reflected in poor-quality diagnostic imaging and, consequently, demands the repetition of the exams, which contributes to the increase of the doses received by the animals being studied and the clinical staff. The doses evaluated in this type of procedure are between 0.43 and 4.22 mGy. This research has shown to be extremely important for the assessment of doses involved in veterinary diagnostic radiology procedures, and as a parameter in the individual monitoring of pet’s owners who assist the animal positioning and occupationally exposed workers of the Department of Veterinary Radiology