B. JOLLES 



decrease in the degree of skin reaction over parts of the irradiated area 

 demonstrated the protective action of some of the substances. Better pro- 

 tection was obtained when 0-005M and 0-0025M sohitions were given 

 immediately before the irradiation. Resuks of 40 experiments in the first 

 series (0-025M solution given after irradiation) are shown in Table I. 



Unequivocal results of a further 25 experiments with injection of weaker 

 solutions before irradiation, confirmed that the method can detect protective 

 agents and may be useful as a screening test. It offers the advantage that 

 hidi local concentration of substances can be examined so as to find a 

 protective agent for skin. 



TR.-\CING RADIOACTIVE PHOSPHORUS INJECTED I NTR AD E RM A L L Y 



It is difficult, and sometimes impossible, to find out by means of directional 

 counters the whereabouts, and the concentration, of radioactive isotopes 

 introduced intradermally. Radioactive phosphorus or zinc or gold colloid 

 is used experimentally for direct infiltration of tumour masses as well as for 

 intraperitoneal and intrapleural applications. The main requisite is that 

 the injected isotope should remain in situ and only conjectural evidence is 

 available that this is so. On the other hand the irregular deposition of 

 particles of the isotope or its diffiision along lines of least resistance within 

 the tissue framework is also known. It is believed that the phosphorus 

 remains in situ, especially when suspended in oil 2. A simple method of 

 mapping out on the skin the whereabouts of the radioactive phosphorus 

 injected intradermally has been devised. It consists in giving a dose of 

 400-800 r to the skin over the injected site. It was found that the cumu- 

 lative effect of radiation due to X-rays, and radiation due to the radioactive 

 isotope will produce a greater skin reaction over areas where both are 

 present, than in those areas where X-rays alone are the reaction producing 

 agent. Simple erythema and desquamative reaction on the skin often show 

 the local distribution of isotopes. ^-P (orthophosphoric acid) diffuses 

 rapidly in the tissues even in oil suspension. The circle and crescent lead 

 applicator can be used for this purpose when the area to be X-rayed is 

 large, thus reducing the extent of skin reaction. 



REFERENCES 



iJoLLEs, B. Brit. J. Radiol. 1941, 14 110; Nature, Lond. 1949. 164 63 ; Brit. J. 



Radiol. 1950, 23 265 ; British Empire Cancer Campaign, 3ht Annual Report, 1954. 

 2WERFF, Van Der, J. Th. Radioisotope T chniques, 1953, 1 78. H.M. Stat. Off., 



London. 



153 



