Pediatric patients benefit from lower doses with 64-slice CT

Scanning pediatric patients with 64-slice CT results in high-quality images and lower radiation dose compared to other multislice machines, particularly when automatic exposure control tools are used, according to research presented Monday.

In one study, the "slower" 64-slice CT scanner resulted in fewer motion artifacts than the faster electron-beam CT scanner.

Dr. Kristen Thomas and colleagues from the Mayo Clinic in Minnesota retrospectively compared image quality and radiation dose between a 64-slice and an EBCT scanner, and between a 64-slice and 4-, 8-, and 16-slice CT scanners.

For abdominal/pelvis exams, the 64-slice scanner produced fewer motion artifacts, better spatial resolution, fewer additional artifacts, and better overall image quality compared to EBCT (p

For chest exams, 64-slice CT resulted in significantly better visibility of small objects compared to EBCT (p=0.013), but no other significant differences in image quality between the two or between 64-slice and the other CT scanners.

Compared to 64-slice CT, EBCT and the other CT devices delivered 75% higher dose on the abdominal/pelvis exams and 111% and 43% higher doses for chest exams, respectively. Researchers noted streak artifacts from high-contrast objects on several 64-slice CT exams, Thomas said.

In another study, Dr. Holger Greess and colleagues from the University of Erlangen in Germany reported similar dose reduction and image quality findings in routine pediatric exams using 64-slice CT. In addition, use of the automatic exposure control tool led to improved pre-scan workflow.

"The automatic exposure control can replace weight-, age-, or color-coded pediatric CT protocols and it improves safe clinical operation, especially in pediatric scanning," Greess said.

Researchers compared 64-slice images using automatic exposure control and 16-slice images with no exposure control in 72 exams. Using automatic exposure control improved workflow by eliminating the need to query patients about weight, length, and age, or to measure distances in the scout view or provide weight-adapted scan protocols.

Automatic exposure control also reduced noise variations within different anatomical regions, Greess said. The average radiation dose was reduced by 20% to 60% compared to weight-adapted pediatric standard protocols for the respective scan regions.

The 64-slice CT images were of a higher quality than the 16-slice CT images in regions with high attenuation such as the shoulder and pelvis. Conversely, quality did not suffer in low attenuation areas such as the lung, Greess said.

Greess concluded that automatic exposure control saves time because it requires no additional user input; it presents no risk of acquiring inferior images; and it harbors no risk of an accidental high dose of radiation.