[Exploitation possibilities of characteristic autoradiations for dermatological radiotherapy]

Several reasons, especially radioprotection of non-affected strata, seem to make it necessary to look for X-ray qualities which effect - in the diseased dermal layers - a more appropriate dose distribution than it was possible to achieve by the X-ray units used so far. Therefore, the possibilities to utilize characteristic autoradiations are examined, i.e. those possibilities being at disposal in the soft-ray range. Practically, there are the series "K" of copper and molybdenum - maybe also those of silver - coming into the question. Using X-ray tubes with copper and molybdenum anodes, the following items are determined, under D.C. operation, in comparison to the wolfram anode tubes which were usually operated until now: Parts of the characteristic autoradiation in the mixture of rays, half-value thicknesses, relative depth doses, stratified half-value depths, the "rates of tissue homogeneity", and - with regard to special care for deeper strate - the "one-tenth value depths" as well as "depth stress factors". The determinations were effected right in dependence on tube tension and focus - skin - distance. The results of the studies, partly demonstrated by practical examples, show that an X-radiation within the so-called soft-ray range corresponds so much the more to the up-to-date conceptions of radioprotection, as this radiation is accepting the characteristics of the monochromatic autoradiation of the anode material. From the clinical point of view, it remains to be exmained preferably whether there will ever be an indication in the range of dermatological radiotherapy that needs a harder quality of rays than those of the molybdene series K.