Year
2023
File Attachment
Abstract
The National Nuclear Security Administration (NNSA) Office of Radiological Security (ORS) is
implementing a radiological risk reduction program promoting the use of non-radioisotopic
technologies in a range of applications, including blood and research irradiation. In support of
this aim, and to assist in the transition from gamma-ray to x-ray based irradiation, ORS funds
studies which examine the efficacy of x-ray irradiation compared to gamma-ray irradiation.
Traditionally, gamma-emitter 137Cs has been used to study the biological effects of radiation
in small animals. To determine the feasibility of replacement with x-ray irradiators in this
application, ORS funded the University of California San Francisco (UCSF) and C&C Irradiators
to compare the rodent absorbed dose rates from a gamma-ray irradiator to an x-ray irradiator
using the same dosimetry techniques on each device. Conventional x-ray irradiators produce
polychromatic x-ray spectra that are typically less penetrative than 137Cs gamma rays and
yield different spatial distributions of dose in anatomical structures. However, careful device
calibration can be used to plan dose to specific tissue types, allowing for controlled use of xray irradiators in place of 137Cs irradiators. This study compares direct dose measurements in
3D-printed rodent mouse phantoms and Monte Carlo simulations of the MOBY-4 mouse model
to quantify the total and organ-specific dose delivered by each technique and establish a
dosimetry system for researchers which can be translated from gamma- to x-ray irradiators.
This work advances scientific knowledge towards the use of x-ray in place of gamma-ray
irradiation in the biomedical research community, and ultimately advocates a more
responsible use of radioactive-related technologies for a safer world