Cover Image

A revised dosimetric model of the gastrointestinal tract /

The goal of this research was to develop a more complete

Bibliographic Details
Main Author: Poston, John W.
Format: Thesis Book
Language:English
Published: [Place of publication not identified] : [publisher not identified] ; 1994.
Subjects:
Major nuclear engineering.
Online Access:http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=741965791&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD
Description
Summary:The goal of this research was to develop a more complete
model of the gastrointestinal (GI) tract for use in internal
dose assessment. The currently accepted model of the GI
tract as provided by Cristy and Eckerman was used as a
starting point. This model was coded into the EGS4
computational package for calculation of specific absorbed
fractions (SAFs). To benchmark the initial code, the EGS4
program was run so that electrons created in photon
interactions were deposited at the point of interaction. The
data obtained from these preliminary calculations were
compared to the data provided by Cristy and Eckerman to
verify and benchmark the program. SAF values were then
calculated for twelve discrete photon energies using the
electron tracking capabilities of EGS4. These photon SAF
values were compared to those calculated without electron
tracking. Absorbed Fraction (AF) values were calculated for
twelve discrete beta particle energies. The electron AF
values were compared to the ICRP assumption for electron
energy deposition in the GI tract. After a review of limited
anatomical data, the model of the GI tract was modified to
better represent the radiosensitive cells of the mucosal
layer of the GI tract. After these modifications were
completed, photon and electron AF values were recalculated
for twelve discrete energies. The final step of the project
was to calculate values of the specific effective energy
(SEE). For samarium-153, SEE values were calculated based
on two sets of AF data. The first set of SEE values were
calculated using the electron SAF values calculated here and
previously published photon SAF values for the currently
accepted GI tract model. The other set of SEE values were
calculated using the photon and electron SAF values for the
revised GI tract model. Both sets of SEE values were
compared to those values provided by the ICRP. SEE values
are also provided for several radionuclides which have a
section of the GI tract as a limiting organ for exposure.
Item Description:Vita.
"Major Subject: Nuclear Engineering".
Physical Description:xiv, 202 leaves : illustrations ; 28 cm.
Issued also on microfiche from University Microfilms Inc.
Bibliography:Includes bibliographical references.