Exposure levels associated with Na(131)I thyroid cancer patients: correlation with initial activity and clinical physical parameters.

Initial radiation exposure levels X (0) at 1 m from the navel of thyroid cancer patients were measured for 165 individuals at the time of ingestion. Some 61 patients had previously signed informed consent so only those patients could be assayed with regard to body parameters. While the activity was in the stomach, resultant X (0) values were seen to be linearly correlated with the total (131)I activity (A) given orally.

Using a single parameter to describe time-activity curves.

Time-activity uptake curves [u(t) in % injected dose per gram of tissue] may be described by different--often complicated--functional forms. Because of the need to readily compare sequences of engineered radiopharmaceuticals, it is efficient to use mean residence time (MRT) as a one-parameter descriptor. In applying this computation to a sequence of five cognate anti-carcinoembryonic antigen (CEA) antibodies, it was found that the intact form had the longest MRT in the blood with the other four cognates having values less by approximately a factor of 10 or more.

Review: update on selection of optimal radiopharmaceuticals for clinical trials.

Multiple formulations of radiopharmaceuticals (RPs) are possible because of engineering at the nanometer scale. Yet, numbers of patients are limited, and the cost of each clinical trial is high. Thus, there is the need of preclinical evaluation of one agent versus another for the selection of an optimal choice.

The two types of correction of absorbed dose estimates for internal emitters.

Background: Two types of correction for absorbed dose (D) estimates are described for clinical applications of internal emitters. The first is appropriate for legal and scientific reasons involving phantom-based estimates; the second is patient-specific and primarily intended for radioimmunotherapy (RIT).

Methods: The Medical Internal Radiation Dose (MIRD) relationship (D) = S A is used, where S is a geometric matrix factor and A is the integral of source organ activities.