Patient Entrance Surface Doses During CT Examinations of Abdomen in General Hospital Karlovac

Computed tomography (CT) has become a major source of the population exposure to diagnostic X-rays, and acknowledge of the doses delivered by the CT equipment has become very important. Considerable efforts should be made to keep these doses to a reasonable minimum, without sacrificing the image quality. The conditions of exposure in CT are quite different from dose in conventional X-ray imaging. This has required the development of specific techniques for assessing patient dose from CT. The aims of this work were to determine the dose delivered to various organs of patients undergoing computed tomography of abdomen as measured on the surface of the body and to estimate the risk to the patients. Dosimetric measurements were performed at CT scanner Hitachi W 450 in General Hospital Karlovac. The doses absorbed by different organs (gonads, chest, thyroid and eye lens) and by the examined part of the body of 11 patients were measured with TLD-700. The doses absorbed by different organs during the diagnostic CT examination of the body depend on the technical parameters, such as the number of scans, mAs, the thickness of scans, scanning times, tube voltage and other characteristics. The type and severity of illness influence the choice of technical parameters. Clinical parameters, such as patient size and composition, and patient cooperation with regard to the control and motion, also influence the dose and the image quality. The highest dose measured in this study (112.5 mGy) was delivered to front surface of the body during CT examination of abdomen. (author)