CT dose

["Douglass, Kenneth Harmon" <KENDOUG@WVNVM.WVNET.EDU>]

Bruce:

CAT and CT are the same; PET is different!

The AAPM prescribed way (report #31, 1990) of measuring patient
dose in CT is to use a cylindrical acrylic phantom. Radiaiton exposure is
measured at the center of the phantom and 1 cm below the surface.
The reported quantity is called CTDI (Computed Tomography Dose
Index) and represents the absorbed dose in a small volume within
the central slice of a multislice exam. Thus it accounts for scattered
radiation from other slices.

With that as preliminary, the CTDI for one of our scanners, based on measuremen
ts   and the typical exposure factors for a spinal CT, is 2600 mrad
at the center and 5600 mrad at 1 cm.


I didn't go to Boston either.

Ken