Multi-slice abdominal CT in oncological patients. Influence of table feed and detector configuration on image quality and radiation exposure

Purpose: To evaluate the image quality and radiation exposure of different spiral CT scanning parameters for routine staging examination of the abdome n in oncologic patients using a multi-slice CT scanner. Methods/Materials: Examination of 40 patients in 4 groups on a multislice CT scanner (Somatom VolumeZoom, Siemens AG, Forch-heim), Functional detector width (4 x 2.5, 4 x 5 mm) and pitch (table feed in relation to collimated slice width) were v aried (3 and 5). Tube voltage (120 kV), effective tube current (160 mAs), s lice-thickness (6mm), increment (4mm), kernel (B30), and contrast injection parameters were kept constant. Axial images were assessed by three radiolo gists regarding delineation of. anatomic structures, artifacts, and overall image quality. Results: Significantly reduced image quality especially due to artifacts was observed using a 5 mm detector configuration with a pitch of 5 (scan time 9 sec), Image quality was rated best for a 2.5 mm detector configuration with a pitch of 3 and a scan time of 28 sec. The effective d ose was independent of the pitch. However, the mean effective dose was 9% h igher using the smaller detector configuration (9.9 mSv vs 10.9 mSv), Concl usions: for routine staging CT of the abdomen use of a 4 x 2.5 mm detector configuration with a pitch between 3 and 5 is recommended. A 4 x 5 mm detec tor configuration using overlapping data acquisition can also be recommende d, but additional thin slice reformations are not possible.