Mammography Doses

["Dean Broga, Director, OEHS" <BROGA@Gems.VCU.EDU>]

I agree in principle with Dr. Siegel, I don't know what the average
person would do with dose information.  Although upper limits have
been set for standard phantom models they do not directly limit the
dose to the individual but more specifically evaluate the imaging
chain.  The overall risk from mammographic sceening is very small. 
If it wasn't, screening of asymtomatic females would not be
promoted. 

At present, few if any technologist can supply specific dose
information.  This may be changing, there are a number of hand held
dose calibrators on the market which when programed by the medical
physicist, can provide glandular dose.  I not sure if this is good
or it is bad.  Dose alone does not indicate image quality, a lower
dose exam may produce a lower quality image and thus defeat the
purpose of the exam.  All nuclear medicine and diagnostic radiology
procedures are a trade-off between dose and information.  The
variables involved are not simple and the outcomes are statistical
in nature.  So we get back to the basic question, what would you do
with the dose information?

For a radiation safety professional, the information might be
interesting.  For the average person, I doubt that it would mean a
thing and the medical staff certainly does not have the time to
educate the general public about radiation in a time of cost
cutting and down sizing.

As of October 1, 1994, all mammography facilties must be certified
by the FDA.  If they are, they have a large framed certificate
which indicates so.  The facility should also be acedited by the
ACR or in a limited number of facilities the State.  If they are
ACR accredited, there should be a sticker on the unit indicating
this.  Any women getting a mammogram at an FDA/ACR facility should
be reasonable confident that she is getting a quality mammogram at
at reasonably low dose.  Beyond that baseline, the question of dose
and quality become complex.

I know of no gender issue in this area.  If the tech doesn't know,
they just don't know.  Male or female, they don't know.  I think
they get frustrated by such request because they feel that the dose
is not an issue.  If the system is properly calibrated, if the
processing is up todate, if the screen/film combination is
appropriate, then thats the best they can do.

Dr. Siegel's coments on other areas are quite apropos.  The last
time the dealer changed the oil on your car, did you ask what
weight oil was used?  I prefer 20W50 in the summer and 10W30 in the
winter.  Whats your preference?

Dean W. Broga, Ph.D.
Director, Environmental Health & Safety
Medical College of Virginia Campus
Virginia Commonwealth University