Effects of single dose proton irradiation of normal skin and Vx2 carcinoma in rabbit ears

and S t i g S t k n s o nHigh-energy protons as well as deuterons and alpha particles have unique radiologic properties (WILSON 1946, TOBIAS et coll.1952).They show a definite range of penetration and the rate of energy loss is many times less a t the point at which the protons enter the tissue than in the latter part of their range.The depth dose curve therefore shows a distinct maximum, the 'Bragg peak', in this latter part of the course, provided that the initial energy spread of the particles is relatively small.The scattering of these heavy particles is, at least for the purpose of tumour therapy, almost negligible, and the proton beam is not especially impeded by bony tissue.The maximum biologic efficiency of the secondary radiation is about 1 per cent of that of the beam.Highenergy protons are thus physically well-suited for precise irradiation of both deep-seated tumours and superficial tumours adjacent t o radiosensitive tissue.A preliminary report of this investigation was given at the Meeting of the Uppsala 217