What does "air kerma" measure?

Air kerma is a measurement that quantifies the energy transferred from ionizing radiation to air, specifically focusing on the kinetic energy of charged particles (electrons) generated within a defined volume of air. This measurement is crucial in the field of radiology because it provides an assessment of radiation exposure, specifically in terms of the amount of energy deposited per unit mass of air, expressed typically in units of gray (Gy) or joules per kilogram (J/kg).

By measuring air kerma, one can understand the radiation intensity impacting an area, which is critical for ensuring safety when exposing patients to radiation and for managing the risks associated with radiological procedures. It reflects the exposure in the context of radiation safety rather than directly measuring the biological effect on tissues or organs, which would be evaluated differently through other metrics such as absorbed dose. Thus, air kerma primarily serves as an important indicator of radiation exposure in diagnostic imaging and radiation therapy environments.