RE: X-Ray Dosimetry for Children

[Kathleen Hintenlang <kathleen@ehs.ufl.edu>]

The University of Florida has a pediatric research group whose overall goal
is to determine, by theoretical calculation and  by experimental
measurement, the absorbed dose to organs in phantoms representing newborn,
one-year-old, five-year-old, ten-year-old, and fifteen-year-old children for
a variety of diagnostic procedures.  

The experimental measurements applied a new methodology utilizing a
prototype anthropomorphic phantom developed at UF incorporating direct
reading MOSFET dosimetry, which allowed the the determination of absorbed
dose to individual organs; the application of current radiation and tissue
weighting factors were utilized to determine an effective dose and risk from
each exam studied.  This research is coordinated by Dr. David Hintenlang of
the Nuclear and Radiological Engineering Department.

The calculational work employs the EGS4 Monte Carlo radiation transport code
with the Cristy and Eckerman MIRD mathematical phantoms for infants and
children that have been revised and updated by Dr. Wes Bolch and Dr. Lionel
Bouchet, also of the Nuclear and Radiological Engineering Department.

I initiated this research based upon the most common plain film procedures
performed for one-year-olds at Shands Children's Hospital at the University
of Florida.  We hope to have results published soon.  Drs. Bolch and
Hintenlang have since expanded the research to include fluoro, CT and
cardiac cath procedures for additional age groups; results for some of these
areas will be presented at the HPS meeting in Philadelphia.

If anyone has more detailed questions, they can reply directly to any of us.



-----Original Message-----
From: Richard, Mack L [mailto:mrichar@iupui.edu]
Sent: Tuesday, April 20, 1999 8:58 AM
To: Multiple recipients of list
Subject: X-Ray Dosimetry for Children


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

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html