A new proposal for monitoring patients in nuclear medicine.

The measurement of exposure rates is fundamentally important in the release of patients given radioactive materials and for keeping the exposures of others as low as reasonable achievable. Similar measurement methodologies have generally been used for point and extended sources, but this approach may lead to methodological errors in calculating radiation dose estimates. In this study, nuclear medicine patients who received high activities of Na131I for therapy were monitored using different measurement methodologies, and the results showed that the usual measurement performed at 1.0 m in front of the body resulted in a mean error of 40% between experimental and theoretical exposure rates. The best measurements were obtained when performed at 2.0 m in front of the patients. With this approach, the error was about 2% between experimental and theoretical values. These findings suggest a new methodology for patients' measurement in nuclear medicine and could be useful for personal monitoring in cases of radiological emergencies involving 131I ingestion.