X-ray beam production

What is the binding force?

Amount of energy that has to be applied to remove an electron from its shell

What is excitation?

Energy transferred to orbital electron causing electrons to jump

What is ionisation?

Energy transferred to an orbital electron, removing it room the electric field of the nucleus

What is a cathode?

Coiled wire where current is applied

What is thermionic emission?

Release of electrons due to heat

What is the effect of the focusing cup?

Different focal length of filament wires produces different amounts of x-ray fields

What happens to the anode in x-ray beam production?

Hit by high energy electrons, causing them to release energy in the form of x-ray radiation

What are the two processes of x-ray production?

Characteristic x-rays

Bremsstrahlung

What is the process of characteristic x-ray production?

Process of ionisation within an atom of the anode

(1) Electron is removed from the inner shell, (2) causing electron from outer shell to drop down, (3) releasing energy in the form of an x-ray

What are the three rules of characteristic x-ray production?

Electron energy must be greater than binding energy

Photon energy is equal to the difference between shells

Different target material produces different x-rays

What is the process of auger electron production?

Inner shell vacancy is filled and outer shell electron can be ejected using the energy emitted

What are the three steps of Bremsstrahlung radiation production?

(1) High energy electron interacts with positive nucleus (2) electron changes direction and loses energy (3) energy is released as x-ray radiation

What are the two causes of differences in energies between electrons?

Electrons interact with the nucleus at different distances and intensities

Electrons keep moving until they lose all their energy or are removed

What is the process of beam harderning?

(1)low energy radiation is more likely to be attenuated (2) there is a reduction in intensity across the entire spectrum (3) increasing the average energy across the spectrum

What is the radiation quantity?

Affects the number of photons, by changing mAs and running more current in the filament to cause more interactions

What determines the radiation quality?

Changes in the distribution of energy and number of photons, by changing the kVand providing more energy to the electrons

What are the requirements of x-ray tube materials?

Filament needs high heat capacity and anode needs to dissipate heat

Housing that shields undesired x-rays with window to allow x-rays in desired direction

What is the focal spot size?

Narrow electron range

Creates area of unsharpness because x-ray focus can’t be a perfect point

What is the line focus principle?

Area of target hit by electrons appears different between the perspective of the filament and the imaging field

How can the anode angle be increased?

Less steep slope

Increases focal spot

Improves heat dissipation

What is the anode heel effect?

Due to sloped anode, some x-rays travel through more material, go through more attenuation and lose more energy