A SKIN TEST IN RADIOBIOLOGICAL 



STUDIES 



B. JOLLES 

 Department of Radiotherapy, General Hospital, Northampton 



The following new technique has been developed for radiobiological 

 investigations of skin recovery and of spreading factors ^ and for clinical 

 work. When a dose of X-rays is given to circular areas of varying diameters 

 surrounded along half their circumference at a distance of 0-5-1 -0 cm by 

 a 0-5-1 -0 cm wide crescent-shaped strip [Figure 1), the skin reaction of 

 the lower half of the circle, i.e. not having in its vicinity an irradiated strip 



Figure 1. Perspex-backed lead applicator 

 with the ' new moon and sixpence ' pattern 



Lead 

 J Tarn, 



3 — Perspex 



of skin, shows a degree of reaction which is less than that on the upper half 

 of the circle and on its neighbouring strip. The potentiadon is due to the 

 vicinitv of irradiated areas, and the decrease in reaction is due to envelop- 

 ment of normal tissues. These differences are not brought about by small 

 variations in the dose actually delivered to different parts of the treated areas 

 as measured by Sievert chambers. 



Qiiantitative data can be obtained from readings of the intensity of 

 reaction at different sectors of the irradiated areas of skin by means of a re- 

 flectance colorimeter specially constructed to the author's specification by 

 Lovibond, Tintometer Ltd., which enables colour changes to be assessed 

 accurately. The colorimeter is similar in shape and size to an electi-ic hair- 

 drier, having a pistol-type grip and being very easily placed into position. 

 When viewing, a circular split field is presented to the eye, the left-hand 

 segment being the colour under examination and the right-hand one being 

 a standard white surface. Both fields are illuminated by a 12-volt lamp 



151 



