Mammography Doses

["Wesley M. Dunn" <WDUNN@brc1.tdh.texas.gov>]

This is forwarded from Tracy Greene, the Texas Bureau of Radiation
Control's Mammography Registration person.  Tracy can be contacted at
tgreene@brc1.tdh.texas.gov or 512-834-6688.


Wes
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The average glandular dose is:

100 millirads per view / film-screen system, no grid
300 millirads per view / film-screen system, with grid
400 millirads per view / xeroradiographic systems

A technologist would not be able to inform the patient as to the
actual dose recieved without taking measurements during the
procedure.  As this would interfere with the procedure, it is not
done.

However, a licensed medical physicist should have surveyed the unit
and performed measurements.  One of the tests required is Average
Glandular Dose.  The medical physicist is directed to use the
technique factors normally used by the facility for one craniocaudal
view of a 4.5 cm. average density compressed breast.

The average glandular dose is obtained by multiplying the average
entrance exposure by a conversion factor based on HVL and
target/filter combination.

The technologist, by reviewing the physicist's report, would have
been able to tell the patient that the average glandular dose for
that particular unit of an average breast is _________. (Whatever the
physicist's report states.)

Radiologic Technology students are told that if the patient
questions them regarding dose to tell the patient that the dose is
minimal and compare it to flying in an airplane or watching a color
television or living in a brick house!  The students are told to
refer questions regarding dose to the radiologist.  The reason is
that there are many members of the general public that overreact to
the word "radiation".