KvP -   one way of controlling the Quality and Quantity of an x-ray beam is to control the voltage of the tube

• by increasing the KvP you increase the energy of the electrons striking the target therefore the photons produced will have a higher energy  (mas stays the same because the number of electrons striking the target stays the same)
• the intensity of the radiation produced is related to the square of the voltage

The Graph of Intensity vs Photon Energy for Different KVP Settings

Target Material (z): the higher the Z of the target material the higher the energy photon is produced and the more higher energy photons there will be (Both the Quality and Quantity are increased)

The higher the atomic number (z) of the target material:

• the stronger the interaction
• the higher the intensity photon will be produced

*Atomic numbers of some Elements used for Target Material:

• Tungsten = 74
• Gold = 79
• Molybdenum = 42

XRAY DISTRIBUTION:  

• x-rays in the 100KV range are distributed evenly in all directions
• as the energy is increased the x-rays tend to travel more in the foward direction

because of this type of distribution for:

low energy photons  - a reflective type target is used   (this is were the electrons and photons ustilized are both on the same side of the target)

higher energy photons  - a transmission type target is used (electrons and x-rays utilized are on the opposite sides of the target)

LINE FOCUS :   the process of making the angle between the anode surface and the central ray of the X-ray beam such that the effective focal spot size is made small as compared to the actual focal spot size

• a bigger focal spot allows for an acumulation of larger amounts of heat before damage occurs to the tungsten target
• the larger the focal spot the less detail can be seen on the x-ray film

Normal target:

this is what the target will look like after the Line Focus Principle is applied:

• we decrease the angle of the anode target the smaller the apparent focal spot will get (apparent source size)

Anode Heel Effect:  (from illustration below) it is generally accepted that an x-ray beam's intensity is not uniform throughout its entirety. As x-radiation is emitted from the target area in a conical shape, measurements have determined that the intensity in the direction of the anode (3) is lower (over and above the difference caused by the Inverse Square Law) than the intensity in the direction of the cathode (1) with the highest intensity being in the center of the film (2). The fact that the intensities vary in such a manner causes visible differences in the density produced on the radiographs. This phenomenon is called heel effect and is illustrated below: