Estudos dosimétricos das varreduras de cabeça em tomografia computadorizada: avaliação da qualidade de imagem visando à otimização de protocolos

Abstract

Computed tomography scan is the diagnostic imaging exam that most contributes to the increase in the population average dose. The head protocols are among those that deposit the highest dose on the patient. This work presents the optimizations of the adult head exam acquisition protocols were accomplished in two computerized tomography scans devices presenting the dose for each protocol and comparing them with the image quality generated. Radiochromic films and ionization chamber and head simulating objects were used for the dose survey. The techniques performed were the automatic current control method and the parameter selection method; and the results of the optimized was verified according with the limits presented in the diagnostic reference levels, aiming at the lower dose associated with better image quality for them to be suggested and used in the radiodiagnosis service of the hospital, in order to obtain a better preservation of the equipment and radioprotection. In this work the full describe detail of the two methodologies of optimization of the adult head exam protocol previously mentioned are presented together with the dosimetric and image quality analysis, which were applied to evaluate the reduction in the dose in the lens with and without the use of bismuth ocular protector. The results presented longitudinal dose profiles for each optimized and non-optimized protocol, the relationship between CTDIvol and central image noise to obtain the best optimized protocol and the efficacy of the bismuth protector without compromising the image quality