Mice and the A-Bomb: Irradiation Systems for Realistic Exposure Scenarios

Abstract

Validation of biodosimetry assays is normally performed with acute exposures to uniform external photon fields. Realistically, exposure to a radiological dispersal device or reactor leak will include exposure to low dose rates and likely exposure to ingested radionuclides. An improvised nuclear device will likely include a significant neutron component in addition to a mixture of high- and low-dose-rate photons and ingested radionuclides. We present here several novel irradiation systems developed at the Center for High Throughput Minimally Invasive Radiation Biodosimetry to provide more realistic exposures for testing of novel biodosimetric assays. These irradiators provide a wide range of dose rates (from Gy/s to Gy/week) as well as mixed neutron/photon fields mimicking an improvised nuclear device.

FIG. 1

Scenarios involving radiation exposure to the general population.

FIG. 2

Comparison of a pure fission spectrum (solid line) and the spectrum from “Little Boy”. Data reproduced from ref. (40).

FIG. 3

Panel a: The neutron irradiation facility [Reproduced with permission from (13)]. Panel b: Sample tube for irradiating mice. Panel c: Sample tube, containing human blood for ex vivo irradiations.

FIG. 4

Low-dose-rate irradiation chamber for (panel a) blood and (panel b) mice.

FIG. 5

Biokinetics of cesium in mouse and man. The full circles represent the time dependent dose rate from ingested ¹³⁷Cs, as per the model described in (10). Open circles are from our own data based on total body counting in mice (49).

FIG. 6

Ultra-low-dose-rate irradiation system under construction.