CHAPTER 29 

 ISOTOPES IN THERAPY AND DIAGNOSIS 



Ellsworth C. Dougherty 



29.1. Introduction. It has not seemed desirable here to survey exhaus- 

 tively the use of radioactive isotopes in therapy and diagnosis. The material 

 presented is merely designed to orient the reader in this general field. For 

 more complete discussions see the review papers by Dougherty and Lawrence 

 [Gen38,39] and the various papers cited in Table 49. Isotopes that have been 

 used or suggested in therapy are given in Table 49. 



Isotopes of radium (specifically Ra 226 ) and radon (specifically Rn 222 ) have 

 been used for almost fifty years in the treatment of various dermatoses and 

 malignancies. For the most part the effectiveness of these isotopes has 

 depended upon the penetrating gamma rays arising from Bi 214 (RaB) and 

 Po 214 (RaC), which are present in mixtures of Ra 226 and Rn 222 in equilibrium 

 with decay products. Rarely, the penetrating beta particles from such 

 mixtures may also be used in therapy. The alpha particles arising from 

 various members of the radium-radon decay system are of negligible impor- 

 tance in this connection. Ra 226 and Rn 222 are today used only locally. 

 In the first two decades of the century both found use systemically — injected, 

 inhaled, or ingested in appropriate vehicles, but the results were not satis- 

 factory. Although records are lacking, some of the individuals so treated 

 must ultimately have suffered "radium" poisoning. Two other isotopes of 

 radium, Ra 223 (ThX) and Ra 228 (MsThi), also found early systemic use. 



Aside from isotopes of radium and radon and those occurring as their 

 decay products the actually and potentially useful species are artificial ones — 

 of the elements sodium, phosphorus, manganese, cobalt, zinc, strontium, 

 yttrium, zirconium, columbium, iodine, gold, and most importantly hydrogen 

 and carbon. 



Although local application of artificial radioactive isotopes has been 

 carried out and will undoubtedly play an important future role, in all likeli- 

 hood replacing radium and radon as therapeutic agents, the particular 

 importance of most useful species lies in their systemic application. Artificial 

 isotopes that so far have shown definite value in therapy and diagnosis have 

 been those that demonstrate a fair degree of selective localization, either 

 as the result of their normal fate in metabolism or of their fate as special 

 compounds or colloids. Thus phosphorus concentrates to a small degree 



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