is human for APPENDIX D RADIATION DETECTION EQUIPMENT FOR JN VIVO MEASUREMENT OF PLUTONIUM ots Bt ae EI ie rhe three following types of radiation detect- thickness. Each detector functions as an anti- iny equipment are currently used to estimate the coincidence system, resulting in a suppression of quantity or plutonium in the body: background caused by Compton scatter from higher- (1) proportional counters; (2) thin sodium iodide crystals and dual iodide; god{um and (3) cesium iodide crystals. Al- energy radiations originating from within the body and in the local environment, The MDA at the 95 per- thoush these instruments are often called ‘lung” cent confidence level for this system averages about counters, 7 nci 239 bu for a 30-minute counting period. they cannot distinguish between radio- active materials in the pulmonary and lymphatic tisgue. =n an effort to localize plutonium, partic- ularly in the hilar lymph nodes, probe is being developed.” 1 an intraesophogeal All of these instruments Measure Sim- ilar MDA values have been obtained at other facilities (for example, at the Lawrence Livermore Laboratory). To achieve MDA's in the range of roughly one-third the commonly accepted 16-nCi low-energy X-rays or gamma rays from pluto. ' ' 243 nium or contaminant radionuclides such as Am 241 formed by decay of Pu. The radiation energies occupational lung burden, one must carefully esti- of Measurements must be made also in "“low-background”’ greatest interest are the 17- to 20-Kev uranium L x-rays From 24 tou and the 60-Kev gamma ray from 241 24] . Am. Low-energy x-rays also emitted by Am mate an individual's chest thickness. Ultrasonic techniques are used for this purpose at LASL. counting chambers constructed of massive iron shielding. must be differentiated from those given off by plutonium, The system used at the Los Alamos Scientific Laboratory to measure im vivo deposits of plutonium ' in our subjects is comprised of two combined crys- REFERENCE 1. K. L. Swinth, J. F. Park, and P. J. Moldofsky, “Counting Plutonium in the Tracheobronchial Lymph Nodes," Health Phys. 22, 899 (1972). tals, Nal backed by a 50-mm CsI crystal, each of which ts about 125 mm in diameter and 3 mm in 24 TAemiamE aE FE ita exist ngewe, or establish- EE: 1353(1030) 31