Aims and objectives
Dose-monitoring software has been introduced to many radiology departments in recent years,
and is well on the way to becoming a ubiquitous tool to monitor and minimize radiation doses for CT scans.
This software is often initially used to review doses of specific protocols,
but can also be used to compare scanners and protocols within one institution,
in order to determine if there exist dose differences between otherwise identical scanners and protocols,
and if so to determine the cause....
Methods and materials
A retrospective analysis was used to evaluate CTDIvol of Head CT scans performed on two identical Philips Brilliance scanners.
The scanners were set up at time of installation with head CT protocols which were intended to be identical.
The analysis was performed by Radimetrics,
a dose-monitoring tool produced by Bayer.
2877 head CTs were analysed in the initial period (1 November 2015 - 1 May 2016),
followed by 4207 head CTs after correction of protocol inconsistencies (1 January 2018 - 1...
Initial Period Mean dose,
CTDIvol (mGy) Following DRI correction Mean dose,
CTDIvol (mGy) Scanner one 30.9 (n=1093) 32.6 (n=1820) Scanner two 36.4 (n=1784) 30.3 (n=2387) CTDIvol of scanner one was 30.9 mGy,
in comparison to 36.4 mGy on scanner two,
an 18% difference. Evaluation of all protocol parameters on each scanner revealed that the protocol parameters that are visible to the reading radiologist - slice thickness,
tube potential and iterative reconstruction mode - were identical across...
Surprisingly large dose variation of 18% was demonstrated between head CT protocols on 2 identical scanners within one institution.
The cause was variation in the predefined noise index setting within the protocols,
which was set to a different level on each scanner.
The predefined noise index is a critical component of the automated exposure control (AEC) mechanism which is integral to every CT scanner (1).Each manufacturer uses different methods to achieve this function (2).
This setting is...
Dr Jonathan N.
Section Chief for Patient Safety,
Assuta Medical Center,
20 Habarzel Street,
Phone 972 3 7645262,
Use ofan automatic exposure control mechanism for doseoptimization in multi–detector row CT examinations:clinical evaluation.
Radiology 2005;237:213–223. 2.
Report 05016 CT scanner automaticexposure control systems.
Available at: http://www.impactscan.