Radiology Lecture 5: Production of X-Ray

What kind of radiation is produced by X-rays?

EM radiation

Do X-rays produce waves or particles?

Wave-particle duality

Are X-rays electrically positive or negative?

Neutral

What is the speed of X-rays exiting in a vacuum?

Speed of light

Do X-rays travel in straight lines or waves?

Straight line

Can X-rays be focused by lenses?

No

What are the two traits of energy of X-rays?

1. Polyenergetic

2. Heterogenous

What are the three main exposure factors on a control panel?

1. mA

2. Time

3. kVp

Which exposure factor on a control panel cannot be changed?

mA

How is the filament temperature described as for milliamperage (mA)?

Incandescence

What is thermionic emission proportional to?

mA

What two factors is the tube current relative to?

1. mA

2. Time

What is time described as in X-rays?

Time it takes for electron to flow from cathode to anode

What is the rule of thumb for mA and time in x-rays?

1. Highest mA

2. Shortest time

What is the primary control factor of X-rays that is direct and linear?

Milliampere-seconds (mAs)

What is mAs used to control for the X-ray?

Quantity

What is the primary control factor of X-rays that is direct and exponential?

Kilovoltage (kV/kVp)

What is kVp used to control for the X-ray?

Quality

Can you change only the quality of the x-ray using kVp?

No, will also affect quantity

What are the two qualities that kVp controls?

1. Energy

2. Penetrability

What two parts of the atom do electrons from x-rays interact with?

1. Nucleus electric field

2. Orbital electrons

What is the interaction of an electron with the nucleus electric field called?

Bremsstrahlung

How are electrons affected in Bremsstrahlung?

Slow (Braking)

What is energy released as in Bremsstrahlung?

X-ray photons

What two factors does x-ray photon energy depend on?

1. Electron keV (kVp of tube)

2. Electron distance from nucleus

What is the energy release of electrons in Bremsstrahlung dependent on?

Amount of change in direction

Does electron braking or change in direction cause higher energy release?

Electron braking

In a Bremsstrahlung emission spectrum, at what photon energy does the intensity peak? (Brems peak)

1/3 kVp

At what two photon energies is the intensity at 0 on a Bremsstrahlung emission spectrum

1. 0 kVp

2. 80 kVp

What is the binding energy of electrons being ejected from K-shell electrons?

-69.5 keV

As the electron is ejected from more outer electron shells, how does it affect binding energy?

Significantly decreases

Is more energy lost going from K to L or K to M electron shells? (Close to nucleus)

K to M

Is more energy lost going from O to L or P to M electron shells? (Far from nucleus)

Negligable

What is the difference of binding energies released as when electrons from another shell drops to fill the void?

X-ray photon

At what photon energy does the x-ray characteristic peak?

69 keV

At what kVp is x-ray characteristic 0%?

65 kVp

How does increasing kVp affect x-ray characteristic percentage?

Increases

How does increasing mAs affect intensity?

Increases

How does increasing mAs affect photon energy?

No change

How does increasing kVp affect intensity?

Increases

How does increasing kVp affect photon energy?

Increases