RADIATION DOSE IN TRACER EXPERIMENTS 

 INVOLVING AUTORADIOGRAPHY 



S, R. PELC 



In many tracer experiments the radiation dose due to the 

 radioactive element hmits the scope of the investigation. The 

 radiation dose should, in all cases, be below a value which 

 would affect the process under investigation, and in many 

 applications, especially those involving humans, radiation 

 damage to organs other than those investigated must also 

 be avoided. To obtain useful results a certain minimal 

 concentration of radioactive material in the final sample is 

 required and this concentration will be one of the determining- 

 factors for the lowest possible radiation dose. Other factors 

 are the time which elapses between application of the radio- 

 active material and removal of the sample, the uptake and 

 excretion of the material and the radiation characteristics 

 and half-life of the radioactive tracer. This paper is an 

 attempt to co-ordinate these factors in a mathematical form 

 which will enable the investigator to estimate the quantity of 

 radioactive material necessary to give the desired result, as 

 well as the radiation dose to the tissues. In some cases calcula- 

 tion might show that an experiment is not feasible, in others 

 the extent of radiation damage might be evaluated. It 

 should be realized that such calculations will normally be 

 based on very insufficient data and the result should be 

 regarded only as a guide in these cases. 



Calculations relevant to this problem have been published 

 by Morgan (1947) and Marinelli (1949), but no comprehensive 

 equations to describe the processes in question seem to have 

 been developed so far. 



The equations given in this paper are designed to meet the 

 needs of the experimenter desiring to produce autoradio- 



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