Radiotherapeutic physics. IV. Some developments of the physical aspects of teleradium therapy.

Abstract

Since the last International Congress of Radiology in Chicago, in 1937, one feature of the development of radiology in this country has been the rapid increase in the number of hospital physicists whose work is chiefly connected with radiotherapy. Coincident with this increase, and not unrelated to it, there has been an increasing measure of collaboration between radiotherapist and hospital physicist in the design and realisation of radiotherapy techniques for the treatment of malignant disease. This close clinical association has certainly been of great educational value to the hospital physicist; it is to be hoped that the radiotherapist has also benefited similarly. In the short time at my disposal it is impossible to deal with more than one facet of this development and that only very inadequately. I have decided to try to outline some of the developments of the physical aspects of teleradium therapy which have occurred since 1937. To this end I shall deal with the subject under two main headings, viz:—(1) apparatus for radium teletherapy; and (2) technique in the use of the apparatus. At Westminster Hospital, from 1936 to the present, two radium mass units have been in use, viz. (a) a 4 gm. unit using a radium-skin distance of 8 cm. and two circular ports of entry of diameters 3·5 cm. and 9 cm. respectively (Flint and Wilson, 1935; Wilson, 1945); and (b) a 2 gm. unit using a radium-skin distance of 5·3 cm. and a single port of entry 3·5 cm. in diameter (Wilson and Pierce, 1938).