Dosimetric response evaluation of tooth enamel for accelerator-based neutron radiation

To study the neutron response of human tooth enamel, a number of experiments with an accelerator-based neutron source have been designed. The neutron beam was produced with the low gamma yield, 7Li(p,n)7Be type thick target, using the 3MV McMaster K.N. Van de Graaff accelerator. The dosimetry was done using a pre-calibrated snoopy type neutron dosimeter. Neutron irradiation induces a dosimetric signal in the tooth enamel at the same defect site as gamma produced damage with the same g-values (g||=1.9973, width 0.4mTg⊥=2.002, width 0.3mT). The dosimetric signal grows linearly with neutron dose from 6–35Gy tissue dose. Dosimetric response in two different grain sizes (300–500μm, and grains <4mm) has shown increased dosimetric amplitude in the larger grains. Dose build up effect on tooth inside the mouth due to cheek was simulated by placing a 4mm thick paraffin wax layer between the beam and tooth, but had little effect. These results show that for mean neutron energy of 280keV, the relative neutron response of the human tooth enamel ranges from 8% to 12% of the equivalent gamma ray response.