98 APPLIED RADIOACTIVITY 



The patient lies on a light frame support with his body bent in an arc 

 which has an outside radius of curvature of 1 meter. The gamma- 

 radiation detector is placed at the center of curvature of the arc. Three 

 observations are then made: first, with the ventral aspect of the body 

 away from the counter; second, with the dorsal aspect away from the 

 counter; and, third, with this position retained the total absorption 

 of the body is directly measured by placing small radium standards 

 behind the patient. From proper mathematical combinations of these 

 measurements the absolute amount of RaC in the body can be computed 

 directly. 



Safety of Personnel Handling Radioactive Materials 



Those persons engaged in handling radioactive preparations must take 

 precautions for their own safety or they will suffer in health. The chief 

 disabilities which may result are : 



(a) Damage to the skin which causes warty growths and ulceration, 

 and which may lead to more serious conditions. 



(6) Damage to the reproductive organs. 



(c) Damage to the blood-forming organs which leads to forms of 

 anemia. 



Damage to the skin is usually due to overexposure to beta rays and 

 is more likely to occur during radon plant manipulations than when 

 solid radium salts enclosed in metal tubes are handled. 



The fundamental rule for safety is that no radioactive preparation 

 should be handled with bare fingers. 



Radium Standards 



One of the international radium standards is deposited in Paris; it 

 consists of 22.23 mg of anhydrous RaCl 2 . The second one, at the 

 Vienna Radium Institute, consists of 30.75 mg. Both were prepared 

 in 1934 by Honigschmid and are composed of pure RaCl 2 free from 

 every trace of barium. 



The United States Bureau of Standards possesses a secondary standard 

 equal to 15.44 mg of radium element as of 1913. 



In a recent number of the Physical Review (1940), it is reported that 

 a series of radioactive standards is being prepared for deposit at the 

 National Bureau of Standards in Washington, D. C, to be used as 

 working standards and to be made available to investigators. 



The standards under preparation are : 



1. Radium standards; 100-cc solutions sealed in 200-cc Pyrex flasks 

 containing 10 — 9 and 10 — n gram of radium to be used as emanation 

 standards either directly or by subsolution. 



