CT Dose

[jhr@ucla.edu (James Rutan)]

Dear Radsafe,

A researcher here at UCLA has submitted a proposal involving the
administration of several 3H-labeled steroids to postmenopausal female
subjects.  Several body composition studies will be performed prior to the
administration of the labeled steroids.  One of these studies will involve a
single cut abdominal CT scan at L2 to quantitate the subjects visceral fat
content.  I was wondering if anyone could give me a ballpark figure for the
dose equivalence for this type of CT procedure.  Also, is it possible to
relate this to an effective dose equivalence which could be added to the
effective dose equivalence received from the labeled steroids.  The
radiologist who will be performing this procedure for the researcher
indicated that the dose equivalence will be from 50 to 100 mrem.  The
Radiation Protection Dosimetry report entitled "Statistics of Human Exposure
to Ionising Radiation" indicates an effective dose equivalence of 1.0 mSv
for CT scans.  NCRP 100 gives a value of 1.11 mSv for head and body CT
scans.  Is there any data for single slices?  I realize the information I've
provided is not much to go on (KVp?, mAs?, slice thickness?, subjects
size?...) but any information you could provide would be greatly appreciated.

James Rutan
UCLA Radiation Safety Office
1010 Veteran Ave.
2195 West Med. Bldg.
Box 951765
Los Angeles, CA 90095-1765

Phone# 310-825-6018
Fax# 310-206-9051
Email: jhr@ucla.edu

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