Fluke Biomedical TNT 12000 - Manual (Page 113)

C-1
Appendix C
Model 500-100 CT Probe
Introduction
The 3.2 cc CT Probes consist of a pencil-type ionization chamber with a sensitive length
of 10 cm. The intended use of these CT probes, with appropriate phantoms, is to measure
exposure produced by computed tomography (CT) scanners.
fct42.eps
Figure C-1. Model 500-100 3.2 cc CT Ion Chamber
The 500-100 probe chamber has a 0.9 meter flexible, low noise cable which is terminated
in a male triax BNC connector. Calibration is stated in terms of R /Coulomb.
Applications
It has been shown 1 that in a phantom, integration of the radiation exposure profile
produced by a single scan from a CT scanner along a line normal to the slice, divided by
the table increment, is equal to the exposure to a central slice at that point produced by a
series of scans. The line of integration must be of sufficient length to intercept not only
the primary beam, but also the Compton scatter produced in the phantom. This integral is
then expressed as R •cm.
1 R.A. Jucius, G.X. Kambic, “Radiation Dosimetry in Computed Tomography (CT)”