Target Interactions: Bremsstrahlung Radiation

_________________ is the most common target interaction.

Bremsstrahlung

________% of the primary beam when set to 80-100kev is bremsstrahlung photons.

80-90%

All x-ray photons below 69KeV are ______________________.

Bremsstrahlung

-characteristic photons are only produced at a level higher than 69kev because it takes at least 69 kev to dislodge a K shell electron

Bremsstrauhlung is a German word for ________________.

Breaking or Slowing

Why do Bremsstrahlung Interactions occur?

The incident electron is attracted to the positively charged nucleus and instead of running into another electron, it reacts with the electrostatic force field of the nucleus.

What happens during a Bremsstrahlung Interaction?

Incident electron reacts with the electrostatic force field of the nucleus

Slows the incident electron

Strong nuclear force deflects the incident electron

At what point is an x-ray photon produced?

When the incident electron reacts with the nucleus's electrostatic force field, it loses kinetic energy, which results in an x-ray photon.

As the incident electron slows down, it loses ___________ energy.

Kinetic

Does the incident electron ever reach the nucleus?

No, not strong enough

Brems interactions ONLY occur when the incident electrons interacts with the ________________.

electrostatic force field of the nucleus

Why are Brems considered to be heterogenetic/polyenergetic?

Because Brems interactions occur at different distances to the nucleus, a wide range of x-ray photon energies are produced.

Non-Uniform Energies

_____________________ contributes to the differential absorption of x-rays within the patient's body by different tissues.

Heterogeneity

As incident electrons get closer to the nucleus of an atom a (smaller/larger) deflection of the incident electron occurs.

Larger

The larger the deflection, the (less/more) energy transferred to the photon.

More

The energy of the brems's photon is exactly the difference between the entering and exiting electron's ______________ energy.

Kinetic

A Brem's photon with high energy will have a _______________ frequency and a ________________ wavelength.

Higher, shorter

Photon's frequency is __________________ related to it's wavelength.

Inversely

-as frequency increases the wavelength shortens

Bremsstrahlung is also known as ____________ or _____________ radiation.

General or White

Operating at 90kVp we will have Brem's photons that range from __________ to _________ kVp.

0-90keV

The majority of the Brem's photons will have approximately _________ of the max energy in a single exposure.

1/3

example:

-at 90kVp the most common photons will be roughly 30keV

What effect does Binding Energy have on Brem's Interactions?

None

Brem's Interactions do not take place with orbiting electrons residing within shells

The higher the atomic # of the target material, the more _________________ the brem's photon becomes.

Efficient

*remember a higher atomic # does not give the brem's photon more energy, that only occurs with characteristic interactions

Incident electron enters with 100keV and leaves with 50keV. How much energy is possessed by the brem's photon released in this interaction?

50keV

100-50= 50

An electron is deflected by a nucleus in a tungsten atom (atomic # 74). The electron had 125 KeV initially and after interaction now had 45 KeV. What is the energy of the brems xray as a result of this interaction?

80keV

125-45= 80

atomic # has no importance in this equation

What makes up the y-axis on an x-ray emission spectrum?

# of x-ray or mAs

***quantity

What makes up the x-axis of an x-ray emission spectrum?

The energy of the beam or kVp

***quality

Brem's x-ray photons have a ___________________spectrum.

Continuous

-everything below the curve demonstrates different brem's photons with varying energy levels

How do Brem's photons and characteristic photons differ on an x-ray emission spectrum?

Brem's photons occur at widely varying energies, whereas characteristic photons occur at a discrete energy level.

When mA, time, or mAs are increased

The # of photons (quantity) Increases, thus, increasing the amplitude of the emission spectrum.

When kVp is increased

The # of higher energy photons (efficiency) is increased, thus, increasing the amplitude of the emission spectrum.

An 80 keV filament electron approaches the nucleus of an atom creating a 75 keV Brems photon. How much keV did the electron have when leaving the atom?

5 keV

80-75= 5

A filament electron leaves the atom with 10 keV having produced a brems photon of 70 keV. How much energy did the filament electron initially have when entering the atom?

80 keV

10+70= 80

A filament electron enters the atom with 120 keV and leaves with 20 keV. What is produced?

A. 100 keV Brems x-ray photon

B. 100 keV Characteristic photon

C. 140 keV Brems photon

D. 120 keV Brems photon

A. 100 keV Brems x-ray photon

True or False: At the target, projectile electrons interact with the nucleus.

False

they interact with the nucleus' electromagnetic force field

The closer the projectile electron is to the nucleus, the _______________ the x-ray photon produced.

A. Greater

B. Smaller

C. Taller

D. Longer

A. Greater

Which of the following electron transitions result in the most useful brems x-ray photon?

A. L to K

B. M to K

C. M to L

D. O to K

E. None of the above

E. None of the above

if it had asked which of these result in the most useful characteristic x-ray photon it would have been O to K (bigger jump)

When a brems photon is produced

A. A projectile electron is absorbed

B. A projectile electron loses energy

C. A target electron is displaced

D. A target electron is excited

E. A target electron is ionized

B. A projectile electron loses energy

When a projectile electron enters a target atom and interacts with the nuclear force field

A. It decreases in velocity

B. It increases in velocity

C. It ionizes the nucleus

D. It removes the nucleus

A. It decreases in velocity

Electrons stay in orbit because they are attracted to

A. Protons

B. Neutrons

C. Electrons

D. Quarks

A. Protons

An atom being a miniature solar system was first demonstrated by

A. Greek

B. Bohr

C. Thomas

D. Dalton

B. Bohr

What is another name for the Z number?

Atomic number

Another name for a valence electron is

An outer shell electron

What is produced when a projectile electron excites an outer-shell electron?

Heat

When a tungsten x-ray tube is operated at 68 kVp

A. K-shell characteristic x-rays can be produced

B. L-shell characteristic x-rays cannot be produced

C. One possible K shell x-ray will have 12 keV

D. Some projectile electrons may have 68 keV of energy

D. Some projectile electrons may have 68 keV of energy

The efficiency of Brems x-ray production increases with increasing

A. Collimation

B. Filtration

C. mA

D. SID

E. Target atomic number

E. Target atomic number