X-ray photon quantity refers to the number of photons produced during an exposure.
Factors influencing x-ray quantity includes:
- peak voltage (kVp): beam quantity is approximately proportional to the square of the tube potential
- generator type/voltage waveform: reducing ripple increases beam quantity
- beam filtration: increasing filtration reduces beam quantity
- distance from the beam: inverse square law
- current (mA): beam quantity is directly proportional to current
- exposure time (seconds): beam quantity is directly proportional to exposure time
- anode material: beam quantity is directly proportional to the atomic number (Z) of the anode material
X-ray photons quality relates to the x-ray spectrum changes and the effective photon energy. The effective photon energy is approximately equal to between one third to one half of the maximum photon energy.
Factors influencing x-ray quality include:
- peak voltage (kVp)
- voltage waveform: reducing ripple increases quality
- beam filtration: increasing filtration increases quality through beam hardening
- anode material: photon energy depends on the binding energies of shells in the anode material
- 1. Walter Huda, Richard M. Slone. Review of Radiologic Physics. (2003) ISBN: 9780781736756