Masters Theses

Date of Award

8-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Nuclear Engineering

Major Professor

Laurence F. Miller

Committee Members

Keith Eckerman, Peter Groer

Abstract

Radiation protection practice requires the knowledge of estimated absorbed radiation doses to aid in the understanding of the potential detriment of various exposures. In nuclear medicine, the radiation dose to the internal organs of the subject are commonly calculated using the MIRD methods and equations. The absorbed dose to the embryo or fetus of the adult female has long been an area of concern. The recent release of the pregnant female phantom series, and its incorporation into the MIRDOSE 3 computer software, has made possible the estimation of absorbed doses from radionuclides in the body to the fetus in early pregnancy, and at three, six, and nine months of gestation. A survey of several major medical institutions was conducted to determine the radiopharmaceuticals which might be given, whether intentionally or not, to pregnant women. Then, biokinetic data for these radiopharmaceuticals were gathered from various documents and other resources, and the absorbed doses to the embryo and fetus at the various stages from radiations originating within the mother's organs were estimated. In addition, information concerning activity distributed within the placenta and fetus was evaluated where quantitative data were available. These reported absorbed dose estimates can be used to evaluate the risk associated with the use of different radiopharmaceuticals, so that a more informed evaluation of the risks and benefits of the various procedures may be made. A wide range of absorbed dose estimates to the embryo/fetus from diagnostic nuclear medicine procedures performed on the mother were determined. The range was from as low as 2.0E-05 mGy (2.0E-06 rad) from the injection of 133Xe to 22.0 mGy (2.2 rad) from 99mTC as sodium pertechnetate. Therapeutic uses of 131I sodium iodide resulted in absorbed dose estimates of up to 500 mGy (50 rad) .

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