BIOLOGY AND MEDICINE INGQASSTF29 With the dose used (225 roentgens repeated weekly for 4 weeks), the tumor incidence was 70 per cent in the unprotected group, but only about 3 per cent in the group with spleen Shielding. The course of changes in the circulating lymphocytes in the unprotected mice indicated that the prolonged depression of the activity of bone marrow and lymphatic tissue was a probable factor in bringing about the lymphoid tumors. Clinical Studies of Radioactive Materials Investigations at Argonne National Laboratory and at Argonne Cancer Research Hospital] have shown that total body radiation results ina large outpouring of amino acids in the urine. Continuing study of this radiation effect in humans and experimental] animals will be directed toward explanation of the mechanism andits relation to protein synthesis and catabolism. In cooperation with Stateville Penitentiary, near Argonne National Laboratory, a study is being made of the rate at which radium is deposited in the body from natural drinking water and food which contain small amounts of radium. Drinking water at Stateville and in many towns around Chicago, comes from deep wells and contains more of this rare element than occurs where the city water supply comes from Lake Michigan or shallow wella. The amount is only a small fraction of that considered unsafe for lifetime consumption, but is enough to make significant measurements possible. Radium gives off radon as one of its daughter products. Hence, when the breath of volunteer prisoners at Stateville is sampled and measured for radon, one can determine the amount of radium present in the skeletons of the volunteers. The individuals are also being measured for gamma radiation by scintillation counting devices. . New-type Scanners for Detection of Diseased Tissues DOE ARCHIVES New types of scintillation counter scanners have been developed at the University of California Radiation Laboratory (Berkeley) for locating and following the path of gammaemitting tracers administered to patients and laboratory animals. One type ~sed for _diagnostic work in humans is a pinhole gamma-ray camera which detects ard locates accurately microcurie amounts of gamma emitters. The practicality of using such small amounts in tracer studies is helpful in that the hazards to healthy tissues are reduced. The pinhole camera scanner consists of a scintillation detector, image amplifier similar to that used in television, and 2 fluorescent viewing screen or photographic film. The fo Ree An me eee Fee dees equipment is 2iso adaptable to any field where accurate location of one or meny beta- gamma emitters is desired, for example, making a gamma-ray photograph of radioactivity resulting from an accident in a laboratory, or in an area where radioactive fall-out may have occurred. A second type of scanner recently developed can be used in both tracer research and clinica] diagnosis. It includes ten adjacent directional scintillation counters which move simultaneously in parallel lines, and thus the scanning procedure is complezed in one- tenth of the time previously necessary. The scanner has proved useful in locating residual thyroid tissue (with iodine 131 as a tracer), and to show the size and shape of the liver and spleen (using gold 198). With this instrument slight abnormalities barely visible on an X-ray plate can be identified with relative certainty as metastatic thyroid lesions. In Figure VI-A, an example is shown of a gamma-ray image of a thyroid car- cinoma patier.t with six metastases. Radioiodine was used as a tracer. By the scanning procedure, an image of the patient is formed as a pattern of dots, each of which represents dh entenmmenwate” a degree of radioactivity. Thyroid cancer growths can thus be detected, and where it is advisable surgery may be performed. (End of UNCLASSIFIED section.) ‘ UNCLASS 17] 2D 51