Etched track detectors and the low dose problem

Abstract

The risk to human health of exposure to low-level radiation is not precisely known yet. One way of studying this is to carry out in vitro biological experiments with cell cultures and to extend the conclusions to biological models. To relate the macroscopically deteminable 'low dose' to the damage of cells caused by a certain type of ionising particle is nearly impossible. therefore the number of hits and the imparted energy are the significant quantities. They can be estimated by particle transport calculations and by direct measurements. The effect of low dose was investigated in radio-adaptation experiments when mono-layers of different unsynchronised cell cultures were irradiated by neutrons produced in the filtered beam of the Budapest Research Reactor (BRR). The energy deposition was investigated by replacing the mono-layers with etched track detectors of the CR-39 type.

Study of the neutron field with etched track detectors in radiobiological experiments

“…According to the previous studies (Pálfalvi et al, 2003) the total neutron flux is 2.2 × 10 6 cm −2 s −1 . To deliver 2 mGy dose (the most often used dose during cell irradiations, it caused the maximum level of radio-adaptation) the irradiation time is 85 s. During this time the cells are affected by 4.4×10 6 cm −2 thermal and by 2.0×10 6 cm −2 intermediate neutron fluence.…”

“…As Pálfalvi et al (2003) had studied the neutron spectrum above 100 keV, efforts were made to get information also below 100 keV, in spite of that the contribution of low energy neutrons to the traditionally defined dose is substantially less than those which have higher energies. At cellular level, where the number of hits can be more reliable than the "dose", the effect of thermal neutrons cannot be neglected as they participate in reactions like 14 N(n, p) 14 C or 1 H(n, ) 2 H in the cell material.…”

“…As a continuation of the previous experiments (Pálfalvi et al, 2003), where the neutron spectrum utilized for the irradiations was investigated in the range of the higher energies, new assemblies of CR-39 detectors (TASTRAK, 1 mm thickness) simulating the cells were mounted on the walls of the cell holder flasks to assess the contribution of thermal and intermediate neutrons. In Fig.…”