Utility of simple radiation dose measurements in the evaluation of different CT scanners used for high-resolution CT.

In recent years radiation risk from CT scanning has become an important area of investigation. Many authors have suggested that radiation dose can be decreased without loss of diagnostic information. This dose reduction has primarily been achieved through a decrease in tube current. An area that has received little attention has been variations in dose from different CT scanners. To evaluate this aspect of radiation exposure, we measured the radiation dose of 4 different CT scanners. We found that the radiation dose for the same CT technique can vary by as much as a factor of 3 when 1 mm slices are used. CT dose variation was greatest for thin slices, making these observations particularly important for high-resolution CT. Our measurement technique used standard quality assurance equipment available in most radiology departments. Use of these measurements to assess the radiation dose from different CT scanners is an easily performed technique that may allow a decrease in radiation exposure in departments by choosing the most appropriate intra departmental CT scanner for specific indications.