5. Measurements with the Barracuda System
CT
Barracuda & QABrowser Reference Manual
2012-10/4.3A
164
parameters, Dose Assessment, Optimisation, Scanner Data, Terminology. 4th Edition,
Hamburg, Germany, December 2002, CTB Publications, D-21073 Hamburg,
ctb-publications@gmx.de
2.
Stamm, G., Nagel, H. D. Software CT-Expo, Medizinische Hockschule Hannover, D-30625
Hannover, stamm.georg@mh-hannover.de
5.8.6 Definition of CTDI
The CTDI is calculated as described below.
Calculations:
CTDI for an individual position is calculated as:
CTDI(100,A(or B C D E)) = Measured CT dose / h
where
h = slice thickness (cm)
The central CTDI is calculated as:
CTDI(100,c) = CTDI(100,A)
The peripheral CTDI is calculated as:
CTDI(100,p) = [CTDI(100,B) + CTDI(100,C) + CTDI(100,D) + CTDI(100,E)] / 4
The weighted CTDI is calculated as:
CTDI(100,w) = 1/3 × CTDI(100,c) + 2/3 × CTDI(100,p)
The volume CTDI for a helical (spiral) scanning is calculated as:
CTDI(100,vol) = CTDI(100,w)/Pitch
where the Pitch is the table movement per gantry rotation. See the CT-SD16 manual
for more information.
___________
For more information on CTDI read the report "Radiation Exposure in Computed Tomography". See section
Parameters for CT Scanner Models for reference.
5.8.7 Quick-HVL and Total Filtration
Use the same procedure as for the normal radiography measurement, however see
section CT kVp about using the topogram program.
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