LAUSR

Abstract Introduction In nuclear and radiological accidents there is a risk of radioactive contamination and accidental intake of radionuclides. Therefore, the individual monitoring of internal exposures is essential for the prompt response to an emergency situation. Individual monitoring allows classifying and evaluating the accident, preventing the increase of contaminated areas and number of affected people and assessing the efficacy of the remediation actions and the decontamination procedures. This study evaluated the use of gamma cameras for individual monitoring of photon-emitting radionuclides incorporated into the human body based on urine samples to apply as a prompt response in emergency situations. Methods For this, a gamma camera available in a military public hospital located in the city of Rio the Janeiro was calibrated using standard liquid sources of 57Co, 22Na, 137Cs and 54Mn supplied by the National Laboratory of Metrology (LMNRI) of the Institute of Radiation Protection and Dosimetry (IRD), all in a 1 L bottle geometry, simulating an urine bioassay. “Efficiency vs Energy” curves at 5, 10, 15 and 20 cm source-to-detector distances were obtained. Based on the “Efficiency vs Energy” curves Minimum Detectable Activities, Minimum Detectable Intakes and Minimum detectable committed effective dose were calculated for 106Ru, 103Ru, 131I, 134Cs and 137Cs at the four source-to-detector distances. Results The results showed that the gamma camera presents Minimum detectable committed effective dose bellow 1 mSv for 103Ru, 131I, 134Cs and137Cs. For 106Ru the Minimum detectable committed effective dose calculated ranged from 1.84 to 3.40 mSv, which is acceptable in emergency situations. Conclusions It has been concluded that the equipment evaluated in this work shows enough sensitivity for use as screening method in accident situations involving intakes of such radionuclides.