XRD Badging

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

Speaking as the Regulations Guru on this specific topic (I'm the
Chair of the Conference of Radiation Control Protection Directors
(CRCPD) Suggested State Regulations (SSR) committee on industrial x-
rays and industrial accelerators), I don't think badging X-Ray
diffraction users utilizing copper targets in interlocked
boxes/beampaths makes any sense.

Keep in mind that a properly collimated x-ray beam is very small
compared to (A) the active area of the badge; and (B) the badge is
very small in comparison to the surface area of the person.  Also,
(C) While the x-ray beam is hot, it is (nearly) impossible to hold
the beam over the same piece of skin, hence distributing the
radiation exposure over a wider area for a lower dose to any one
place.

Extremity badges make some sense if you are working around the target
and/or collimator while the unit is energized (which some people
claim is necessary).

Whole body badges make sense if users are clueless and are using
a non-interlocked and/or poorly shielded/collimated tube housing OR
you are using non-copper targets (e.g., larger characteristic x-rays).

NEVER adjust/modify/remove the tube housing while the unit is plugged
in and/or power is available to the unit.  Then you avoid the
incidents that Ted describes.

As a side note: Several years ago, we did a study using two TLDs
in series (e.g., one in front of the other) and a copper-filtered x-
ray beam.  We verified that the first badge was sufficient to shield
the body.  Hence, if you have a badge reading, the person behind the
badge was not really exposed to the radiation.  So badges DO have a
protective function (albeit for a very small surface area).

P.S., we are in the process of promulgating proposed rule-making to
the effect of the above comments.


Wes

Chair, SR-3 Committee