Evaluación de la calidad de imagen y de la dosis en exámenes de TC helicoidal de tórax en pacientes con carcinoma de pulmón. Resultados preliminares.

Abstract

We have applied criteria for CT quality defined in the European Guidelines to a sample of thoracic CT examinations - for the indication of pulmonary carcinoma - of 5 institutions of the Community of Madrid that have spiral CT equipment. The selected examinations have been evaluated independently by five radiologists to determine the degree of adherence to the quality criteria for image defined in the Guideliness for examinations of general thorax. Dosimetric measurements carried out in parallel have served to estimate the values of CT (CTDIw) dose indices, dose-length product (DLP) and effective dose for every patient. The results show a high global adherence to the quality criteria (96%), with averages per institution being between 94% (in two institutions) and 98% (in three institutions). There are 10 of 16 criteria that are adhered to in all examinations of the sample; those which are not adhered to systematically are: two of visualization (1.1 and 1.4), with 92-96% fulfillment, and four of critical reproduction (2.6; 2.8; 2.9 and 2.10), with percentages of adherence between 91% and 96%. The average CTDIw values per institution are in the interval 12.9-19.1 mGy; those of DLP between 263 and 577 mGy cm and those of effective dose between 4.2 and 9.2 mSv. The DLP-image quality correlation in institutions with the best image quality was null in two of them and direct and moderate in the third. In both institutions with the poorest image quality, the correlation was inverse and moderate in one and direct and weak in the other. Reasons for these results are analyzed, as well as possible ways of optimizing quality in relation to dose and parameters used.