The MCART Radiation Physics Core

Abstract

Dose-related radiobiological research results can only be meaningfully compared when radiation dosimetry is standardized. To this purpose, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Medical Countermeasures Against Radiological Threats (MCART) consortium recently created a Radiation Physics Core (RPC) as an entity to assume responsibility of standardizing radiation dosimetry practices among its member laboratories. The animal research activities in these laboratories utilize a variety of ionizing photon beams from several irradiators such as 250-320 kVp x-ray generators, 137 Cs irradiators, 60 Co teletherapy machines, and medical linear accelerators (LINACs). In addition to this variety of sources, these centers utilize a range of irradiation techniques and make use of different dose calculation schemes to conduct their experiments. An extremely important objective in these research activities is to obtain a Dose Response Relationship (DRR) appropriate to their respective organ-specific models of acute and delayed radiation effects. A clear and unambiguous definition of the DRR is essential for the development of medical countermeasures. It is imperative that these DRRs are transparent between centers. The MCART RPC has initiated the establishment of standard dosimetry practices among member centers and is introducing a Remote Dosimetry Monitoring Service (RDMS) to ascertain ongoing quality assurance. In this paper we will describe the initial activities of the MCART RPC toward implementing these standardization goals. It is appropriate to report a summary of initial activities with the intent of reporting the full implementation at a later date.

Scattered Dose Calculations and Measurements in a Life-Like Mouse Phantom

“…These systems have high-resolution imaging capabilities, technically precise robotic movements, and energies scaled to match the small animal geometries. Concurrent to the rise in popularity of these irradiation systems has been a call for accurate and standardized dosimetry within small animal models (5, 6). …”

“…The widespread usage of small animal models has spurred development of physical phantoms of mice as well. Simple mouse phantoms, which are often no more than a tube with slots for the insertion of a detector, are prevalent for dosimetry (3, 5, 6, 21). The rise in popularity and capability of rapid prototyping tools, such as 3D printers and computer controlled milling machines, has allowed for a new generation of physical mouse phantoms with intricate features that closely mimic the animals they represent.…”

A Model for Precise and Uniform Pelvic- and Limb-Sparing Abdominal Irradiation to Study the Radiation-Induced Gastrointestinal Syndrome in Mice Using Small Animal Irradiation Systems

“… 1 , 3 , 6 , 7 The dose–response relationship for ARS-related mortality is often very steep, and even a 5% to 10% variation in dose can result in markedly different outcomes. 10 In previous studies, abdominal irradiation has typically been performed by placing mice in a single anterior orthovoltage irradiation field while shielding the bone marrow within the thorax, head, and extremities with lead. 1 , 3 , 6 This leads to some uncertainty in the delivered radiation dose depending on radiation field uniformity (heel effect) and placement of animals in relation to the lead shielding as well as nonuniformity of dose throughout the abdominal cavity.…”

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

“…It is becoming clear that experiments involving animal models require accurate and reproducible irradiation dosimetry as a crucial part in radiobiological investigations. (Kazi et al 2014) Without accurate and reproducible delivery of radiation dose, the results of radiobiological experiments will be hard to interpret and possibly misleading.…”