Quantitative Biological Dose Control in Interstitial Radium Therapy

Abstract

Among the noteworthy events in modern radiotherapy the publication by Paterson and Parker (1934) of their radium dosage system ranks high. In the past decade the rules and dosage graphs have found practical application in most radiotherapy institutions. Moreover, the basic assumptions in Paterson's dosage system have withstood the test of clinical experience and now stand solid and sound, although when first published they were backed by experience gained from clinical application over a period of two years only. In the chapter on biological aspects, a “serviceable tumour lethal dose” of 6000 r for epitheliomata, delivered over a limited period of time, was suggested. “This dose can be given in some way or other in the majority of normal situations to the whole of an accessible tumour of moderate size without destruction of normal tissues”. “For ordinary regions, tongue, skin, breast, soft parts in healthy condition, the range of tolerance to implantation is from 5500 r to 7000 r. It would seem that the smaller the implanted volume the greater the tolerance” (Paterson and Parker, 1938). The effective dose capable of causing a chain of events leading eventually to the resolution or disappearance of a tumour is, in the case of epitheliomata, in the region of 6000 r delivered in seven to ten days, provided the distribution of radium sources is good. The problem of an optimal or effective tissue dosage is a most complex one, as many physical and biological factors are involved.