A fine focus x-ray tube contains a focal spot smaller than 0.5 millimeters.

(FWHM) The full width at half maximum is a parameter to characterize the width of a peak on a graph. In nuclear medicine, the FWHM is used to determinate the energy resolution of gamma camera systems.

A gamma quantum is a distinct photon of electromagnetic radiation with the highest energy, shortest wavelength. The energy of a single photon is above 100 keV, the wavelength is below about 10 picometers. Gamma photons are generated by processes within the atomic nuclei.

See also Quantum.

(gf) The grid frequency is the number of lead strips per inch or centimeter. An increased grid frequency involves thinner stripes. The most used grid frequency is 85 -103 lines per inch.

(lx) Lux is the SI unit of illumination. Lux is based on lumen, and lumen is a derived unit based on candela. One lux is equal to the intensity of light on a surface that is 1 m from a uniform point source of one candle intensity or equal to one lumen (lm) per square meter.
The formula is:
1 lx = 1 lm/m²