Poole — On the Distribution of Activity in Radium Therapy. 475 



absorption of brass and animal tissue for ^ rays to be approximately the 

 same). In all cases considered t = 3-0 mm. 



The figures so obtained would represent the activity if the secondary 

 radiation in the flesh were identical with that on the skin in contact 

 with a brass radiator, as K was determined from the " brass " curve. In the 

 interior the increased secondary radiation due to the tissue raises the 

 total activity by about 10 per cent., so in the results shown below this 

 correction has been applied to all depths exceeding 3 mm. Appropriate 

 corrections are applied for smaller depths, no correction being required 

 at the surface. 



Three sets of figures have been worked out and are shown in columns 

 B, C, and D of the following table, the corresponding conditions being 

 explained below : — 



Explanation of Table. 



a is the distance in millimetres of the point in the tissue at which the 

 activity is given in the other columns. For the figures in column A 

 (emanation needle) a is the distance from the axis of the needle ; for the 

 other columns, a is the distance from the surface of the skin. 



