When investigating the effects of radiation on living organisms, it is important properly characterize the radiation field to which the organisms are exposed, and to accurately and reproducibly determine the energy absorbed by the tissues of the organisms. The energy absorbed per unit mass of tissue, or absorbed dose, is the quantity customarily used to characterize the strength of the radiation field. Knowlege of the absorbed dose and characterization of the biological effects at different dose levels permits the generation of the dose-response curve for an organism due to a given type of radiation. The dose-response curve can then be used to predict the effect of radiation on a population of organisms.

Absorbed dose may be measured using a variety of techniques and instrumentation. Classical modalities include ionization chambers, calorimetry, film densitometers, chemical systems and thermoluminescence dosimeters. The DRDL group has developed expertise in using solid-state electronic dosimeters such as metal-oxide-substrate field-effect transistors (MOSFETs) to measure radiation dose. MOSFETs change their electrical characteristics instantaneously upon radiation exposure. This rapid response permits real-time monitoring of absorbed dose. DRDL has used the MOSFET method to measure the radiation dose rate in both x-ray and radionuclide-based small animal and cell irradiators. Accurate calibration of these devices is essential in assuring that the total radiation dose delivered to a biological sample during an irradiation is accurately known.

Find out how the DRDL can help you improve the quality of your radiobiology research by contacting the DRDL director, Dr. Terry Yoshizumi.