Radiological Research

It was the veteran American philosopher, John Dewey, whose writings first brought explicitly to my notice the useful distinction between “having to say something and having something to say”. Being placed in the situation indicated in the first half of that phrase, what indeed have I to say? On such an occasion as this we may attempt a wider perspective of our art and science, hoping to escape what Coleridge calls “the voice and lash of the imperious ever-recurring this day”. May we therefore spend a few minutes trying to assess our position, recalling some of the journey here, enjoying the view and examining some of the landmarks the better to direct our future search? Thirty years ago looking at medical radiology it was (I suppose naturally for a physicist) impressed upon me that the main problem was some adequate system of measurement and control of radiation, chiefly, in the first instance, for the protection of the patient. Anyone who saw the results of radiation therapy carried out at low voltages, of necessity with almost unfiltered X radiation, must have been impressed by this need. The problem was to control and define the amount of radiation, first of all on the surface, then at a depth, and finally as distributed throughout the patient. It was relatively easy to devise technical means of making a measurement; the real difficulty was to interpret such observations in a system which was theoretically sound and capable of great extension.