AbstractID: 6747 Title: Radiation Profile Evaluation of a Multislice CT Scanner
The performance evaluation of a multislice CT scanner (Light Speed QX/i, General
Electric Medical Systems) was recently conducted at our facility. The results from the
study were compared with that for a single slice CT scanner (HiSpeed Cti, General
Electric Medical Systems). Special attention was paid to the radiation dose profile at the
isocenter, in lieu of the fact that the multislice CT scanners are less dose efficient than the
single slice CT scanners. Radiation beam width significantly higher than the specified scan
width (especially for the total beam width less than 5 mm) was seen for the multislice CT
scanner. This also reflected in the measured radiation output, which was nonlinear with
respect to the slice thickness for the multislice CT scanner. For the single slice CT
scanner the measured radiation profile were within 1 mm of the specified scan width and
the radiation output was linear with respect to the slice thickness. Comparison to earlier
study shows that the measured radiation profile at the isocenter for the multislice CT
scanner is smaller than previously reported. This improvement in radiation profile at the
isocenter is attributable to the fact that the newer version of the scanner has
“conventional” X-ray beam tracking system. Improvements to the existing beam tracking
system have to be made to have the dose efficiency of the multislice CT scanner
comparable to a single slice CT scanner.