View Full Version : CT-Scan conversion factor for limbs.

12-18-2003, 07:26 PM
Dear all,

In order to assess the radiation exposure of a new in-vivo protocol we are currently developing (using CT-Scan) we found various methods are available.

Some of them are very simple, but not accurate. More accurate assessment can be made using about 10 parameters related to the Ct-Scan experiment we are dealing with.

I found a very good document called "Radiation Exposure in Computed Tomography" (by H.D. Nagel et al., 2000, 83 pages). It seems to be used as the de facto assessment standard in the field (at least in Europe). So, I guess we can trust this.

Q1- My first question is:

Can we see this particular reference as the best source to assess radiation exposure ? Is there any other documents that would be more recelty published ?

Reading the document, several methods are described. The most accurate of them (in order to quantify the Effective Dose, E, in mSv) uses a bunch of parameters including a conversion factor f (in mSv/mGy.cm) that is used to calculate E according the regions of the body being imaged (example, f for the head is < that f for the abdomen) and the patient (various values for female/male/children/babies).

The given table for f is quite complete ... except for the anatomical regions that is of interest for us: the limbs and the extremities (i.e. hands and feet).

Q2 - My second question is:

Do you have any idea of the magnitude of this conversion factor f for the limb and limb extremities?

Q3 -

>From the text, I can understand that the "skeleton effective dosis is about twenty times lower then for the gonads". Gonads have a f around 0.035 and 0.025 mSv/mGy.cm (for an adult male and female respectively). Can we assume that the skeletal f is 20 times lower ?

Thank you in advance for any answer !


Serge VAN SINT JAN, PhD, Assoc. Prof.
University of Brussels
Dept. of Anatomy (CP 619)
Lennik Street, 808
1070 Brussels
Email: sintjans@ulb.ac.be
Phone: +32 2 555 6325 (-76)
Fax: +32 2 555 6378

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