A biological dosimeter using mammalian cells in tissue culture and its use in obtaining neutron depth dose curves

Ehrlich mouse ascites cells have been used as a biological dosimeter to check physical methods of measurement of central axis depth doses of a beam of fast neutrons. The cells were irradiated in suspension in Perspex tubes, using air or nitrogen bubbling. Irradiations with fast neutrons under aerobic conditions were carried out at four depths in a tissue-equivalent phantom and in the absence of the phantom. The relative intensities of the radiation under these conditions agreed well with measurements using a special ionisation chamber, provided allowance was made for accompanying γ radiation. The oxygen enhancement ratio was found to be 2·78 with 250 kV X rays and 1·80 with the fast neutron beam. No signicant change of OER was observed for irradiations at 8·7 cm deep in the phantom.