Performance of an automatic dose control system for CT: anthropomorphic phantom studies

To assess the performance and to provide more detailed insight into characteristics and limitations of devices for automatic dose control (ADC) in CT.

A comprehensive study on DoseRight 2.0, the ADC system provided by Philips for its Brilliance CT scanners, was conducted with assorted tests using an anthropomorphic phantom that allowed simulation of the operation of the system under almost realistic conditions. The scan protocol settings for the neck, chest and abdomen with pelvis were identical to those applied in the clinical routine.

Using the appropriate ADC functionalities, dose reductions equal 40% for the neck, 20% for the chest and 10% for the abdomen with pelvis. Larger dose reductions can be expected for average patients, since their attenuating properties differ significantly from the anthropomorphic phantom. Adverse effects due to increased image noise were only moderate as a consequence of the "adequate noise system" design and the complementary use of adaptive filtration. The results of specific tests also provided deeper insight into the operation of the ADC system that helps to identify the causes of suspected malfunctions and to prevent potential pitfalls.

Tests with anthropomorphic phantoms allow verification of the characteristics of devices for ADC in CT under almost realistic conditions. However, differences in phantom shape and material composition require supplementary patient studies on representative patient groups.