RADIUM INJURIES AND RADIUM POISONING 97 



radium, the rate of elimination is below 1 per cent of the quantity remain- 

 ing in the system. Several years later the daily rate of elimination is 

 down to 0.002 to 0.005 per cent per day. At this low rate it would 

 require 45 years to eliminate half the radium in the system. 



About 90 per cent of the eliminated radium is excreted in the feces, 

 and the remaining 10 per cent in the urine. No radium is eliminated 

 through the skin. Since radium decays into radon with the emission 

 of an alpha particle, the radon thus formed can be exhaled in the breath. 

 The fraction of the radon expired varies between extreme limits of 2 

 and 40 per cent of the total amount of radon produced in the body by 

 the decay of radium. 



Depending on the resistance of the individual's system from 2 to 

 10 micrograms of radium, when " fixed " in the system, may be a fatal 

 dose. 



The radioactive self-photographs of the bones of deceased victims 

 show a lack of uniformity of distribution of deposited radium. In some 

 individuals two or three small areas have been found to be intensely 

 radioactive, the remainder of the bone displaying only a moderate 

 amount of fairly evenly distributed radiation. This lack of uniformity 

 in the deposition of the radium shows that an analysis of a fragment of 

 bone chosen at random will not be representative of the nature of the 

 deposit. 



Radium acts principally to destroy the blood-producing centers and 

 to weaken the bones. Necrosis of the jaw, osteogenic sarcoma, and 

 regenerative anemia are among the most common symptoms of radium 

 poisoning. 



An ingenious method has been developed by Evans and Aub [1937] 

 for measuring the gamma radiation from RaC in the patient's body and 

 for determining the absolute amount of RaC from these observations. 

 It involves the use of a very sensitive form of Geiger-Miiller counter 

 responding to gamma radiations. 



In a victim of chronic radium poisoning, the radium is deposited non- 

 uniformly throughout the bones, the highest concentration being in the 

 vertebrae. The emitted gamma radiation is reduced by absorption 

 and scattering of the tissue. The emerging radiation does not lend 

 itself to computation of the RaC content of the patient, so that cali- 

 bration observations are resorted to in order to evaluate the radiation. 



The effect of non-uniform distribution of radium and of internal 

 absorption and scattering by the patient's body can be completely 

 corrected by making a series of gamma-ray observations in which the 

 patient is placed in definite geometrical relations with respect to the 

 gamma-radiation detector. 



