Fluke Biomedical 76-419-4150 - Manual (Page 7)

Operation
§1020.33 Computed Tomography (CT) Equipment
2
2-1
Section 2
Operation
§1020.33 Computed Tomography (CT) Equipment
Reprinted from: “21CFR 1020.33” pages 535-540.
A. Applicability
1. The provisions of this section, except for paragraphs (b), (c)(1), and (c)(2) are applicable as specified herein to
CT x-ray systems manufactured or remanufactured on or after September 3,1985.
2. The provisions of paragraphs (b), (c)(1), and (c)(2) are applicable to CT x-ray systems manufactured or
remanufactured on or after November 29, 1984.
B. Definitions
As used in this section, the following definitions apply:
1) Computed Tomography Dose Index (CTDI) Means
The integral of the dose profile along a line perpendicular to the tomographic plane divided by the product
of the nominal tomographic section thickness and the number of tomograms produced in a single scan;
that is:
Where:
z = position along a line perpendicular to the tomographic plane.
D(z) = Dose at position z.
T = Nominal tomographic section thickness.
n = Number of tomograms produced in a single scan.
This definition assumes that the dose profile is centered around z=0 and that, for a multiple tomogram
system, the scan increment between adjacent scans is nT.
2) Contrast Scale Means
The change in linear attenuation coefficient per CT number relative to water; that is: