X-Ray Dosimetry for Children

["Richard, Mack L" <mrichar@iupui.edu>]

Dear Radsafers:

A researcher here wants to perform a number of x-rays of children (ages
4-18) in support of a research study (i.e., the patient receives no
benefit).  In adults, I generally try to calculate an effective dose (or
effective dose equivalent) and compare that value with the effective dose
equivalent quoted in NCRP 93.  One of the problems I'm running into is
determining organ doses for children.  There is an old (1979) publication by
the BRH (now the CDRH) entitled "Handbook of Selected Organ Doses for
Projections Common in Pediatric Radiology" that addresses some of the x-rays
the researcher wishes to perform; however, it doesn't cover all of the
views.  Related to this issue I have a few questions that I hope someone can
shed light on.

1.  How does one calculate organ doses from x-rays in children where no data
(i.e., organ dose per entrance exposure) is available?

2.  Would it make sense to calculate the organ doses to adults (much more
data available) and multiply by 2 or 3 (ICRP 62 states risk to children is 2
to 3 times that of an adult)?

3.  Even the available data do not address organ doses (e.g., to the bone
marrow) from extremity x-rays.  Is it necessary to calculate effective dose
(equivalent) from x-rays of the extremities e.g., lower legs, hands, feet,
etc.) and if so, how would one go about it (This applies to adults as well)?

4.  Has anyone attempted to translate the effective dose equivalent quoted
in NCRP 93 (360 mrem/yr) to effective dose?

Any ideas or references (I have looked up some references, but they don't
appear to have all of the necessary info) would be appreciated.

Regards,

Mack L. Richard, M.S., C.H.P.
Radiation Safety Officer - IUPUI/Indiana Univ. Med. Cntr.
Phone #: (317) 274-0330   Fax #: (317) 274-2332
E-Mail Address:  mrichar@iupui.edu

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