A patient contact shield visible in the localizer-the effects to tube current modulation.

An anthropomorphic phantom was scanned with Siemens Somatom computed tomography scanners using tube current modulation (TCM). Thorax of the phantom was first scanned without the use of a contact shield, followed by a scan with a 0.5 mm lead equivalent out-of-plane shield placed in the localizer but 1 cm caudally outside the scanned volume. Scans were repeated using the scanner's organ radiation dose reduction feature. Pitch values 0.35, 0.6, and 1.05 were used. With a pitch of 1.05, the effects of TCM varied between scanners from 4.35% to 356% when scanning toward the caudal end of the scanned volume, when shield was used outside the scanned volume. Also, with some scanners, the use of XCare increased the cumulative tube current.