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RE: Equine Radiography
I will try to answer your concerns with my own research. I taught radiology
and radiographed primarily large animals at Oregon State University for 10
years at the Veterinary Medical Teaching Hospital. First let me state,
while I was there, NO ONE ever hand held a portable x-ray unit - we used a
tripod stand; and we utilized cassette holders to place the person holding
the cassette a minimum of 3 feet from the animal.
We ran static tests of exposures using Bowie, Min-X, and Kramex, portable
x-ray units. These units are single phase, half wave, using a 30" SID.
Most of these units utilize a fixed mA, (usually 20) and fixed kVp (80).
There are some variable units that fluctuate from 10 to 40 mAs and 60 to 90
kVp. We used only the Bowie unit for our tests, using 80 kVP and .25
seconds per exposure and 400 speed rare earth screens and film (an average
carpus study on a 10-11 cm leg).
The result was that the tube leakage from the BACK of the box amounted to
.25 to .75 mRem PER EXPOSURE. This unit I have seen held by operators
against the upper femurs/pelvis to steady the unit during .25 to .5 second
exposures for carpus and tarsus of the horse. We did not calculate a
gonadal dose at that time. Larger doses were calculated for doing stifles
on the horse, with the x-ray machine at a chest level and .75 seconds even
with 800 rare earth film/screens.
I cannot encourage the veterinarians/technicians doing this type of
radiography to utilize all available resources for reducing the exposure
they are receiving. This means lead aprons, stands for the machine, and
cassette holders for the film.
Please feel free to contact me directly with further questions;
Richard Kay, MSc, RT(R)(M), MSRP, FASRT
Imaging Resources, Inc.
richard@imaging-resources.com
-----Original Message-----
From: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of
alstonchris@netscape.net
Sent: Tuesday, October 15, 2002 9:29 AM
To: radsafe@list.vanderbilt.edu
Subject: Equine Radiography
>Date: Tue, 15 Oct 2002 12:23:22 +0930
>From: "Crawford, Leonie (EPA)" <Leonie.Crawford@DHS.SA.GOV.AU>
>Subject: EQUINE RADIOGRAPHY
>
>The Aushorse and Thoroughbred breeders association have recently announced
>an X-ray policy for yearling sales to be held next year. The policy is
>simular to one developed by Keeneland ( USA,s biggest sales company) over
>the last 5 years. 34 X-rays are requires for each yearling and must be
taken
>within 42 days of the commencement of sale. Horses sold into Hong Kong
have
>42 films taken. Some sites are having their weanlings X-rayed to detect
>early problems that can be remedied prior to being sold as yearlings.
>Approximately 22 films are taken. All of the above does not include any
>repeats required. Recent research into how the radiography is conducted
has
>shown that: 1.All x-ray cassettes are being hand held, 2.Veterinary
surgeons
>are hand holding the portable x-ray units to do the radiography. Having
>seen the procedure in part, I can understand why they employ these
>techniques. With the new X-ray screening protocol coming into force in
>Australia, the high number of films being taken by a small pool of persons
>and the radiation doses of persons involved in the procedure will receive
>should be of concern. Does anybody have any information or knows of
surveys
>carried out to evaluate the radiation doses received by veterinary surgeons
>in the USA involved in these screening procedures for yearlings? One local
>veterinary clinic here will probably do 150 to 200 horses.
>
>
>Leonie Crawford
>Specialist Radiation Protection Officer
>Radiation Protection Branch
>Tel: 81300715
>Fax: 81300777
>Email: Leonie.Crawford@saugov.sa.gov.au
>
>"The information in this e-mail may be confidential and/or legally
>privileged. Use or disclosure of the information by anyone other than the
>intended recipient is prohibited and may be unlawful. If you have received
>this e-mail in error, please advise by return e-mail or by telephoning 61
>81300715."
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