212 Applied Biophysics 



pose, for instance, that instead of being delivered in one month, 

 a volume dose of 7 or 8 megagram-rontgens is to be given to 

 a patient in treating a tongue in one day. It might be that, 

 under such conditions, volume dose is a limiting factor. Such 

 a possibility is not inconceivable in the light of the hypothesis 

 suggested by Gray ^ that the number of fractions rather than 

 the total time is more important. If this is true, then techniques 

 might be developed necessitating the administration of very large 

 doses in many fractions in a very short time. 



What Biological Phenomena Can Be Correlated With 

 Volume Dose? 



The phenomena must be general, as distinct from local, and 

 may be subjective or objective. 



Subjective phenomena such as malaise, nausea, vomiting, and 

 headache are very difficult to correlate, especially since so many 

 of these symptoms might be produced by general upsets not due 

 to radiation. 



Objective phenomena may be measurable or not. Here we 

 shall consider measurable phenomena only. They may be divided 

 into (a) blood counts, (b) other measurements. 



Blood counts are the easiest tangible evidence to obtain of 

 the effects of radiation. 



Ellis "^ tried to correlate the blood counts, corpuscular volume, 

 and other factors, with volume dose. No correlation was pos- 

 sible. Figure 13 shows types of lymphocyte counts obtained. 

 Althought there is an average trend, individual counts behaved 

 very differently, even rising during relatively rapid administra- 

 tion of radiation at some part of every curve. Other types of 

 cell are much more erratic. Thus correlation in individual cases 

 is impossible. From the work of Bush,- however, there appears 

 almost a mathematical correlation. Figure 14 is based on average 

 lymphocyte counts of 26 cases treated for carcinoma of the 

 mouth, pharynx and larynx. The possibility of individual varia- 

 tions as in figure 13 still, of course, exists. Experience of 

 abdominal-bath treatments provides the same type of curves as 



