872 



THOMAS ORDWAY AND ARTHUR KNUDSON" 



course of chronic diseases, independent of treatment. The importance 

 of the psychical effect of any treatment must also be considered in thera- 

 peutic work. Encouragement from the fact that something- (frequently 

 the more unusual the greater the effect) is being done is often, at least 

 temporarily, very beneficial to patients suffering from a chronic disease. 

 It is important to establish definitely in an objective manner how metab- 

 olism is affected by these physical agents and then to proceed very cai 

 fully to their therapeutic application. 



Measurement (Standardization) of Radioactive Substances and of 

 Roentgen Rays. It is extremely important that detailed information of 

 the exact technique be included in reports, so that the work may be dupli- 

 cated by others. In the past the difficulty of standardizing the energy of 

 x-rays has led to varying results and the measurement of the activity of the 

 x-rays by their effect upon chemical pastilles or photographic films have not. 

 proven satisfactory. The development of the Coolidge tube has made it 

 possible to secure the desired milliamperage as distinct from the voltage 

 and the recently devised stabilizer prevents fluctuations in the current. 



The relation of the methods of measurement of x-rays as expressed 

 in erythema dose is indicated in the following table : 



TABLE I 

 TABLE OF COMPARATIVE X-RAY DOSAGE 



Erythema Dose .. 



Coolidge tube 40 milliampere minutes at a distance of 

 10 inches, 60 kilovolts and without any filtration; 60 mil- 

 liampere minutes with nitration of 1 mm. of aluminum. 



Special ionization chambers have been devised to measure the n 

 tensity of Roentgen rays. A chamber termed the ionto quantimeter for the 

 clinical measurement of x-rays, suggested by Szillard of Paris, is de 

 scribed by Knox. Duane made a similar apparatus and placed it betweei 

 the source of the x-rays and the object to be rayed. Glockner and Reus 



Amplified after U. S. A. X-ray Manual. New York: Paul B. Hoeber, 1919. 



