x-ray scanners

["Mike Malaxos" <rss@arach.net.au>]

Would some Radsafers out there care to comment on the following.

I am very interested in the Health Physics Community comments re the
routine scanning of persons for diamond or other theft detection
(administering a
free air dose at the skin entrance position of around 15 microgray per scan
at 300
scans per year).  The ethics of this practice may be of prime importance.

Informed Decision.
		Should special efforts be made to ensure that the various dose response
theories and risk estimates are understood before a person is considered
informed enough to agree to be routinely x-rayed. This could be difficult
with persons who have had limited schooling?

Should the risk benefit equation be increased in scope to consider
secondary benifits such as higher wages, increased employment duration
span, less chance of being coereced into stealing  the product and benefits
to the rest of the community etc?

If the risk benifit equation is considered in its simplistic form could
benefit to the individual be artificially increased by addition medical
care such as improved diet, immunisation, regular check-ups etc. for the
rest of that persons life?

If this narrow interpretation is not followed could the company
administering this dose be liable for compensation in the future when
15-24% of this workforce die from naturally occurring cancer which may be
perceived to be caused by the x-ray scanning.


Scanning Systems.
		It is generally considered that image intensifiers used for medical
screening have reached their useful maximum efficiency in relation to dose
minimisation because of limits imposed by quantum mottle. 

Digital receptors provide the most dose reduction by storing the image and
reducing "real time exposure". The scanning technique, utilising a 5 mm
wide fan beam and a narrrow strip detector, which does not see the scatter,
improves  contrast by reducing the degradation caused by scatter within the
body.

Is their any other type of scanners available which reduce the skin input
dose to less than 10 microgray and will detect a 2 mm diamond swallowed or
inserted in a body orifice using heavily filtered 120 kVp x-rays?

Is it considered that the weighting factor of this energy radiation may be
as high as 2 or 3 because of the generation of photo electrons?

Have other forms of detection systems which do not use x-rays been
successful?

Should random sequence x-rays be carried out to reduce the collective  dose
or
does the fear of unfair increased xray examination rate because of personal
bias negate any  gain achieved by reducing the collective dose?

Is the dose so low that any hazard associated with 2-3 microgray
insignificant?
A typical Odelca 100 mm photofluorography system for chest x-rays (93 kV
-120 mAs) delivers a skin location input dose (in air) of 3450 microgray . 

If the theft rate is high enough to limit the life of an operation and
therefore the security of the employment should this fact be considered
part of the risk benefit equation.

Does the low level scanner produced by Nicolet Imaging Systems of San Diego
produce a skin entrance dose of a few microrem as claimed or is the average
dose higher.

  

Best Regards
M.Malaxos
Radiation Safety Services
69-71 Robinson Avenue Belmont
Western Australia.  6104 
Fax 61 89294 1533
email rss@arach.net.au
 

Best Regards
M.Malaxos
Radiation Safety Services
69-71 Robinson Avenue Belmont
Western Australia.  6104 
Fax 61 89294 1533
email rss@arach.net.au