Phantom studies for possible dose reduction in CT head procedures

This paper presents the results of phantom studies to investigate possible dose reduction in relation to image quality in head examinations. The studies were performed using five single-slice computed tomography (CT) scanners. Beginning from the manufacturer's protocols (i.e. default protocols in the scanner software) for routine head (adult) examinations, the values of kVp, anode current and time were modified. Low-contrast resolution and spatial resolution were controlled using a Catphan 424 phantom. Radiation dose was checked using a polymethylmethacrylate phantom and a pencil ionisation chamber. It was found that CT dose index may be reduced up to three times with practically no loss of image quality. (authors)