Patient dosage in computed tomography

The maximum surface dosage in most clinical CT scans seems to range from 2 to 10 rads/study but much larger dose per study values seem possible with both rotate-translate and rotary geometry designs. The CT scanner type in itself does not significantly reduce doses. Secondary radiation dose values were measured for critical organs and indicate that dosage from secondary radiations may be reduced significantly by external shielding. Dose values in the vicinity of most CT scanners are typically 1 to 2 mrad/scan at 1 meter at the parameters of a typical clinical scan