50-MEVd leads to Be neutrons: a comparison of normal tissue tolerance in animals with clinical observations in patients.
The acute and late effects of 50 MeV neutrons were investigated by irradiating a variety of organ systems in large animals using dosage schedules similar to those that have been employed clinically. The RBEs for acute effects in pig skin and rhesus monkey oral mucosa were significantly less than the RBEs for late effects. This observation has also been noticed clinically. The RBEs for late effects in pig skin, rhesus monkey oral mucosa, and rhesus monkey kidney were consistent with values of 3.1 to 3.4 relative to approximately 200 rad 60Co fractions and approximately 2.2 to 2.6 relative to approximately 400 rad 60Co fractions. The RBE for radiation myelitis was significantly greater (4.2 to 4.6 relative to approximately 270 rad 60Co fractions). The tolerance doses for 50 MeVd leads to Be neutrons in large animals were approximately 2200 radn gamma/61/2 weeks for skin contraction, approximately 2100 radn gamma/61/2 weeks for oromucosal necrosis, approximately 1300 radn gamma/41/2 weeks for radiation myelitis, and approximately 960 radn gamma/4 weeks for radiation nephritis. These values correlate well with clinical observations at TAMVEC, since the majority of soft tissue complications in patients occurred following tissue doses in excess of 2100 radn gamma.
D000818:Animals; D003037:Cobalt Radioisotopes; D005214:Fast Neutrons; D006801:Humans; D007668:Kidney / Q000528:radiation effects; D008253:Macaca mulatta; D009061:Mouth Mucosa / Q000528:radiation effects; D009502:Neutrons; D011833:Radiation Injuries, Experimental / Q000209:etiology*; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000009:adverse effects*; D012062:Relative Biological Effectiveness; D012867:Skin / Q000528:radiation effects; D013116:Spinal Cord / Q000528:radiation effects; D013552:Swine; D013997:Time Factors
D003037:Cobalt Radioisotopes