The Clinical Application of Heat 



71 



Quality of Radiation: Transmission by Textiles 



The study of the quaHty, or dominant wave length, of infra- 

 red radiation under conditions of chnical treatment is a difficult 

 one, and little progress has heen made. Some advance can be 

 made by comparing different types of source, such as, for 



18 20 



r 



(wave length) 



FIG. 4. Wave length distribution of radiant energy from a heat cradle. The area 

 (1) represents the energy from the bulbs, which is all the energy emitted in the first 

 minutes of treatment. The area (2) is radiation from the cradle background after one 

 hour of use; the total energy emitted after one hour from switching on the cradle 

 is represented by the sum of (1) and (2). The figure shows not only that the energy 

 transmitted to the patient increases greatly with time, but also that the additional 

 radiation from the background will escape detection if a glass-enclosed thermocouple 

 is used. The wave length beyond which glass will cut off all radiation is marked by 

 the dotted line. 



