200 



Applied Biophysics 



dealt with, and curves were constructed from which volume 

 doses delivered with X-rays of HVL 2 to 4 millimeters Cu 

 can be estimated quickly and fairly accurately. Boag's measure- 

 ments indicate that the volume dose depends principally upon 

 the area and site of the field. The FSD linear dimensions of 

 the patient and HVL of the beam have much less effect. 



Photographs of the model are shown in figures 4 and 5, and 

 curves representing some results in figures 6 and 7 from Boag.^ 



FIG. 4. CIrimmett's ionization-cliamber '"man" in position for treatment to tlie head. 



(From Boag.^) 



FIG. 5. Photograph showing the general appearance and method of construction of 

 the trunk of Grimmett's ionization-chamber "man." (From Boag.^) 



