Re: Minimum thickness of CT/MRI data

From: Robert Thompson (
Date: Fri Jul 11 1997 - 02:48:59 EEST

Dear All,
One point not mentioned with regard to radiation exposure in CT is the fact
that a set of overlapping slices acquired Helically (Spiral CT) delivers
significantly less exposure to the patient than the same set of overlapping
slices acquired axially. This is due to the fact that in spiral CT the
slice spacing can be determined retrospectively, that is after the scan. So
a patient can have a 3mm scan, reconstructed at 1 mm intervals, and receive
the dose equivalent of a 3mm scan - three times less exposure if the scan
was acquired at 3/1 or 1/1 axially.

As for MR, 0.25mm thicknesses are possible - but who wants their protons
flipped ???

Robert G. Thompson
Biomodelling Engineer
Anatomics Tel. 61 7 3364 0776
Queensland Manufacturing Institute Fax. 61 7 3364 0786
P.O. Box 4012, Eight Mile Plains Em.
Q 4113 Australia Web

Anatomics : The Biomodelling Specialists Enhancing Patient Care.

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