Radiation, Animals and Dosimetry (RAD) Core

Columbia University Health Sciences, New York NY

Investigators

Abstract

The goals of the Radiation Animals and Dosimetry (RAD) Core are to provide precise rat irradiations with accurate dosimetry. All three projects use a common animal model, the WAG/RijCmcr rat model. This model accurately recapitulates the full sequelae of multi-organ injury to the hematopoietic, gastrointestinal, pulmonary, renal, and cardiac systems observed in NHPs and humans. The RAD core will centrally provide and maintain rats for all three projects, and provide all care and sample collection required within the first 21 days after irradiation. The Core will provide: PBI/BM5 (leg out; 5% bone marrow shielding) irradiation of unanesthetized rats using a) photons, b) neutrons with an energy spectrum mimicking that of a nuclear detonation, and c) Ultra High Dose Rate (UHDR) electrons.  X rays will be provided using a standard, filtered X ray machine at a dose rate of about 1 Gy/m. hind leg shielding will be performed using lead. Irradiations will be accompanied by NIST-traceable dosimetry, using an ion chamber.  Neutrons mimicking the energy spectrum seen at Hiroshima at 1-1.5 km from the epicenter will be generated by the Columbia IND neutron facility. Hind leg shielding will be implemented using borated polyethylene. Dosimetry will be performed using a tissue-equivalent ionization chamber. A compensated Geiger Muller counter will be used to measure the γ-ray dose associated with the neutrons.  UHDR irradiations will be performed using our modified medical linac, with the total dose delivered in a few msec, mimicking the blast from an IND. As with the X rays, hind leg shielding will be performed using lead. Irradiations will be accompanied by NIST-traceable dosimetry, using an ion chamber. Central to reliable and reproducible irradiation and dosimetry is an effective quality control system. The RAD Core has in place a series of Standard Operating Procedures (SOP) covering operation and dosimetry for all irradiation platforms used in this program project. The Core will collaborate with the NIAID-wide Radiation Physics Core to ensure that these SOPs are in accord with the accepted irradiation procedures across NIAID. While standard dosimetric techniques will be used for most experiments, the Core will use advanced customized technologies to address the challenges of some of the proposed irradiation modalities. Organ dosimetry and dose verification will be performed using a unique heterogeneous rat phantom, and Monte Carlo simulations.