Comparison of RBE values of 15 MeV neutrons for damage to an experimental tumour and some normal tissues

Abstract

-A 15 MeV deuterium-tritium neutron generator yielding between 1 x 10 12 and 3 x 10 12 neutrons per sec was used to measure damage in the EMT6 tumour, bone marrow, oesophagus, and lung of the mouse. RBE and OER values for the tumour are relatively close to those previously reported for the R-1 rhabdomyosarcoma in the rat, the RBE ranging from 6.3 at 50% survival of hypoxic cells downward as a function of dose and the OER for neutrons being 1.8. The RBE's for bone marrow CPU's, oesophageal lethality, and pulmonary lethality were 1.6, 4, and 2.2, respectively. These results confirm the relative consistency of rodent tumours in response to neutrons and add further evidence of the wide range of RBE's to be expected in normal tissues.