Loyola University Medical Education Network

Internal radiation dosimetry

As was the case with diagnostic radiopharmaceuticals, the goal is a minimal radiation dose absorbed by both the patient, who is probably having a one-time therapeutic procedure, and the Physician or Nuclear Medicine Technologist, who is routinely exposed to radioactive patients on a daily basis. The usual rules of the TDS concept apply: one should minimize TIME, maximize DISTANCE, and use the appropriate amount of SHIELDING.

There are specific rules governing the release of patients from the hospital after administration of a therapeutic radiopharmaceutical; in routine clinical practice not involving IND's, they apply most often to I-131. The release criteria are set by the NRC and state that the patient may be released when his radiation burden becomes <30 mCi or when a reading taken 1 meter from the patient's chest is <5 mR/hr, whichever level is reached first. These actions minimize the risk to family members and to the general public.


Stephen Karesh, PhD.

Last Updated: August 14, 1996
Created: March 1, 1996