OBSERVATIONS MADE ON THE HUMAN 



RESPONSE TO A SINGLE DOSE OF X-RAYS— 



THE LATENT PERIOD 



W, M. Court Brown and John D. Abbatt 



Medical Research Council, London 



It is clearly desirable that human material should be used for radiobio- 

 logical investigations. This can only be done if a reproducible response to 

 irradiation occurs, of which at least some of the governing factors are known. 

 The length of time which elapses from the commencement of irradiation to 

 the onset of the symptoms of radiation sickness, the latent period, seems 

 such a response. Experience with more than 150 patients has shown that 

 provided a large enough single dose of irradiation is given to a large enough. 



Irradiation of whole length of spine 

 (Ankylosing spondylitis) 



«^ 250 



^ 



200 



^ SO 





J L 



J \ \ L 



volume of tissue in the trunk, or to the whole body, a symptomatic dis- 

 turbance occurs which is sudden in onset, and that the time required to 

 initiate this disturbance can be measured with reasonable accuracy. Experi- 

 ence with control sham irradiations has indicated that the symptoms which 

 terminate this latent period are the genuine symptoms of radiation sickness ; 

 these symptoms are acute and sudden nausea, and the development of 

 uncontrollable and often persistent vomiting. Observations on the latent 

 period have been made in two classes of patients : those irradiated with 

 medium kilovoltage X-rays and those given large doses of ^^^I. This 

 period and the ensuing symptomatic disturbance, together with such physio- 

 logical changes that occur, appears to correspond to the initial phase of the 

 General Radiation Syndrome in man and may well be the himian equivalent 

 of the first phase of response in the rat as described by Lamerton and his 

 co-workers^. 



229 



