Air KERMA (Kinetic Energy Released per unit MAss of air) measures the amount of radiation energy in air, unit is J/kg. This include the initial kinetic energy of the primary ionizing particles such as photoelectrons, Compton electrons, positron//negatron pairs from photon radiation, and scattered nuclei from fast neutrons, when for example air is irradiated by an x-ray beam. J/kg (gray) is also the unit of the radiation quantity 'Absorbed Dose'.

The angular response is the reaction of the detector to particles or photons which hit the detector at angles deviant from a normal to the facial plane of usual incidence.

An antiparticle is a subatomic particle similar in mass but with opposite electromagnetic properties. Most particles have their antiparticles, electron - positron, etc. Antimatter is composed of antiparticles. Colliding of a particle with its respective antiparticle leads in case of low-energy particles mostly to photon production, in case of high-energy particles to exotic heavy particles.

A cassette is a thin, low x-ray absorption plastic case, for holding the x-ray film. Inside the cassette are intensifying screens for the conversion of x-rays to visible light photons. The intensifying screens are mounted in close contact with the film. Mammography cassettes are equipped with single screens.

The cerebral blood pool can be imaged with single photon emission computed tomography (SPECT) and positron emission computer tomography (PET) techniques. The used radiopharmaceuticals are technetium-99m labeled red blood cells (RCBs) for SPECT and O-15 labeled water for PET imaging. Measured can be cerebral blood volume, brain perfusion and cerebral metabolism.

See Cerebral Metabolic Imaging, Fluorodeoxyglucose, Regional Cerebral Blood Flow, Coincidence Detection, Annihilation Coincidence Detection and Cyclotron.