Bibliogr. s. 59

Background: Optimization of X-ray diagnostic procedures requires a selection of exposure parameters adequately for the patient anatomical structure and clinical needs, meanwhile use of the ready software protocols is a daily routine. The paper presents the methods and the results based on phantom studies aimed to optimize the exposure parameters for the examined object in examinations performed using single-slice CT scanners. Material/Methods: The studies were concerned with the significance of particular exposure parameters for image quality and patient doses in routine head procedures. Image quality was evaluated using a Catphan 424 phantom. Dosimetric measures of exposure were evaluated by computed tomography dose index (CTDI), and dose-length-product (DLP) was measured using a Nomex dosimeter. Results/Conclusions: Two single-slice CT scanners were investigated in details: a fourth generation one (Picker PQ-2000) and a third generation one (Siemens Somatom Balance). The dependence of image quality factors on high voltage, anode current, scan time, slice thickness were described and CTDI was evaluated. For both the CT scanners tested, the combinations of exposure parameters were found for which low dose value was accompanied by good image quality. Moreover, the high-contrast resolution was not practically changed with dose reduction, in opposite to low-contrast resolution being related to exposure parameters and the type of CT scanner. Dose reduction possible for the fourth generation scanner is deeper.