• Before X-ray tube can be used to produce X-rays it must be supplied with a suitable current of high voltage (measured in k v) and low amperage (measured in m A).

• It is these two properties of the electrical supply which control the nature and quantity of the X-rays produced.

The effect of kilovoltage

• The passage of high voltage current across an x-ray tube which result in the production of x-rays. The higher the kilovoltage used for this purpose, the more rapidly the electrons travel, the greater the amount of energy released on impact, and the shorter the weave-length of the x-ray produced.

• X-ray of short wave length are sometimes described as "hard" X-ray, while those of longer wave length may be spoken of as "soft".

The effect of millamperage

• The amount of current which travels across an X-ray tube during an exposure depends on the number of electrons available to carry that current which in turn varies with the current supplied to the filament in the cathode. The tube current (measured in Millamperage is directly related to the amount of X-ray produced.

• The amount of x-ray produced during a given exposure also depend on the length of the exposure and expressed in milliampere-seconds or mA-s.

• The above effect are often summarized by stating that the killvoltage affects the quality and the millamperage (more correctly the mA-s) the quantity of the X-ray produced by a particular apparatus.