Coulomb is the SI unit of electric charge. One coulomb is the amount of charge accumulated in one second by a current of one ampere.
The charge of a proton is 1.6 x 10^-19 coulombs. The charge of an electron is - 1.6 x 10^-19 coulombs. An atomic particle has a charge which is an integral multiple of 1.6 x 10^-19 coulombs.

A count is a single event recorded by radiation detection equipment.

The craniocaudal view is routinely used for mammography. The vertical x-ray beam is directed from cranial to caudal through the breast.

A critical organ is the body part receiving the highest dose or experiencing the highest risk from radiation exposure.

A crossed (or cross-hatch) grid consists of crossed stripes, also available with rhombic angles. This type of grids is not suitable for the use of a tube angle.