VADER: a VAriable Dose-rate External 137Cs irradiatoR for internal emitter and low dose rate studies

TL;DR

VADER is a novel device that uses discarded Cs-137 seeds to simulate low dose rate external gamma irradiation for biological studies, enabling safer and more accurate modeling of environmental and accidental exposure scenarios.

Contribution

This paper introduces the VADER system, a new apparatus that models low dose rate external Cs-137 irradiation using existing brachytherapy seeds, improving upon internal emitter study limitations.

Findings

VADER can deliver dose rates of 0.1 to 1.2 Gy/day.

It allows long-term, simultaneous exposure of multiple mice.

The system accurately mimics Cs biokinetics in biological models.

Abstract

Beyond prompt irradiation, Cs-137 is likely to be the most biologically important agent released in many accidental (or malicious) radiation exposure scenarios. Cs-137 either can enter the food chain or be consumed or if present in the environment (e.g. fallout) can provide external irradiation. In either case, due to the high penetration of the 662 keV gamma rays emitted by Cs-137, the individual will be exposed to a uniform, whole body, irradiation at low dose rates. The VADER (VAriable Dose-rate External Cs-137 irradiatoR) allows modeling these exposures, bypassing many of the problems inherent in internal emitter studies. Making use of discarded Cs-137 brachytherapy seeds, the VADER can provide varying low dose rate irradiations at dose rates of 0.1 to 1.2 Gy/day. The VADER includes a mouse "hotel", designed to allow long term simultaneous residency of up to 15 mice. Two source platters containing ~250 mCi each of Cs-137 brachytherapy seeds are mounted above and below the cage and can be moved under computer control to provide constant low dose rate or a varying dose rate mimicking Cs biokinetics in mouse or man. We present the VADER design and characterization of its performance.