Final Review Xray production (interactions in the xray tube) Flashcards by Melissa Unknown

electrons interacts with the atomic
nucleus, more energy is lost and a stronger x-ray is
produced; account for the majority of the x-ray beam.

Bremsstrahlung

How well did you know this?

Not at all

Perfectly

electrons interact with an
orbital electron from the atom, the pulling down of
another electron from an outer shell causes an x-ray to be
produced; account for a small majority of the x-ray beam

Characteristic Radiation

How well did you know this?

Not at all

Perfectly

Be able to label the different interactions based off the diagrams and be able to tell the difference on xray emission spectra (in packet 10 that was handed out)

How well did you know this?

Not at all

Perfectly

Xrays versus gamma rays

-xrays are man made process
-xrays originate from electron cloud of atoms
-gamma rays are a neutral process
-gamma rays originate from atomic nucleus through radioactive decay

How well did you know this?

Not at all

Perfectly

Velocity of accelerate electrons

Speed of light

How well did you know this?

Not at all

Perfectly

Incoming electrons=

incident electrons

How well did you know this?

Not at all

Perfectly

Increase kinetic energy of incident electrons also increase:

-Increases quality and quantity
-increases number of target interactions

How well did you know this?

Not at all

Perfectly

Bremmstrahlung is the german term for:

“Breaking or slowing radiation”

How well did you know this?

Not at all

Perfectly

Bremsstrahlung is responsible for how much percentage of the xrays produced in the xray tube:

85%

How well did you know this?

Not at all

Perfectly

Molybdenum
-lower atomic number
-ideal for soft tissues of breast

Mammography

How well did you know this?

Not at all

Perfectly

-high atomic number
-high melting points
-similar binding electrons

Tungsten and rhenium

How well did you know this?

Not at all

Perfectly

Occur within 2.35-0.5mm of target surface

-heat production
-Bremsstrahlung interactions
-Characteristic interactions

How well did you know this?

Not at all

Perfectly

Is a very inefficient process

xray production

How well did you know this?

Not at all

Perfectly

The closer the incident electron passes to the nucleus

The higher energy of the photon

How well did you know this?

Not at all

Perfectly

Further away to the nucleus

The lower energy of the photon

How well did you know this?

Not at all

Perfectly

increased wavelength and decreased frequency =

decreased energy

How well did you know this?

Not at all

Perfectly

decreased wavelength and increased frequency =

increased energy

How well did you know this?

Not at all

Perfectly

-contains low energy xrays which will be absorbed by the xray tube
-average energy of the beam is 1/3 of the maximum energy
-xrays are an inefficient process
99%heat, 1% converted to xrays

Heterogenous Beam

How well did you know this?

Not at all

Perfectly

Portion of beam from tube to the patient; radiation before it enters the patient

Primary Radiation

How well did you know this?

Not at all

Perfectly

Radiation emerging from patients body to expose the film; image forming radiation

Remnant Radiation

How well did you know this?

Not at all

Perfectly

These 4 prime factors are controlled by the technologist

mA- milliampere
S- seconds time
kVp- kilovoltage peak
SID - source to image distance

How well did you know this?

Not at all

Perfectly

The range and intensity of xrays emitted changes with different exposure technique settings on the control panel

Xray emission spectrum

How well did you know this?

Not at all

Perfectly

A Brem photon is the result of

The energy difference between the incident electron as it passes (slows) near the nucleus

How well did you know this?

Not at all

Perfectly

Brem Radiation involves

An incident electron and the nucleus of an atom

How well did you know this?

Not at all

Perfectly

The inner shell of an atom

K shell

How is brem radiation produced

By slowing of an incident electron

-incident electron interacts with electrostatic force field of nucleus -Mutual repulsion (slows electron) -Strong nuclear force (Keeps them apart and deflects incident electron and repulsion causes a deceleration of incident electron)

Bremsstrahlung interactions

Brems responsible for wide variety of energies

-produces a continuous spectrum of xrays -heterogenous xray bream

Results of Brems interactions

-Deceleration yields xray photons energies -xray production is continuous during deceleration -accounts for largest portion of total xray beam -photon energy dependent on how close electron comes to nucleus and rate of deceleration

Brems energy produced dependent on

-how close to the incident photon gets to the nucleus (closer creates increased energy) - the degree of deceleration of the electron (greater deceleration created increased energy)

Brems process at atomic level :

-high speed electron is attracted to the positively charged nucleus - interaction with nuclear force fields causes electron to slow down and lose energy -lost kinetic energy converted to X-ray energy

Two interactions part of X-ray production

Bremmstruhlung interactions and characteristic interactions

True or false Electron interacts directly with nucleus

False : slim chance an electron will hit or interact with nucleus directly and if that happens all energy will be lost

As incident electron gets closer to nucleus, the following occurs

-photon energy increases due to rate of deceleration - larger deflection of incident electron -electrons with small amount of residual kinetic energy, become part of electrical current flow

Characteristic X-ray production involves

Incident electron and inner shell electron

Less of a turn=

Less energy of a photon

The process of adding or removing electrons from an atom is

Ionization

Responsible for 15% of X-rays produced in the X-ray tube

Characteristic

Characteristic process at atomic level

-high speed incident electron interacts with an inner shell (k or l) shell electron or a target atom -k or l shell electron is ejected , leaving a vacancy -electron vacancy filled by another electron from an outer shell (characteristic cascade) -electron transition responsible for producing a characteristic X-ray photon

Binding energy of kshell is

69.5

Characteristic can be produced at what amount of keV

70 or higher

What kind of energy spectrum does Brem produce

Continuous

The process of an outer shell electron filling a vacancy left in an inner shell

Characteristic cascade

-hole in inner shell and must be filled by electron from any outer shell - electron energy difference -secondary photon produced

Characteristic cascade

What shell is of diagnostic value

K shell

Brems is produced at what keV

anything is less than 70

The cascade process is associated with:

Characteristic radiation production

Changing (blank) will change the maximum energy of the photons in the X-ray emission spectrum

KVp

A technologist can control the quantity of the X-rays striking the patient by adjusting the

The maximum kinetic energy of a projectile electron accelerated across an X-ray tube depends on the

Kilovoltage

Beam quantity is primarily determined by

mAs

What can be determined from an xray spectrum

Maximum photon energy and average photon energy

-Brems and characteristic emissions combines -consists of a "brems hump" and characteristic peak -selected kvp will determines maximum kev possible for any photon

Emission Spectrum

Characteristic radiation is produced when:

A vacancy in an electron orbit is filled

How kilovoltage effects emission spectrum

Created potential difference -determines the speed of the electrons in tube current -greater speed results in greater quantity and quality of primary beam -Increasing electron speed will increase xray beam penetribilty Example: *kvp is increasing, shift to the right, increases average energy*average and maximum energ increased when kvp is increase

How mA affects the emission spectrum

Unit to measure tube current or number of electrons flowing per unti time -mA directly proportional to quantity of xrays produced -double the mA will double the number of xray photons produced Example: *mA is increasing so its doubling quantity but mA does not affect the energy of the xray beam*

xray tube filtration filters out

low energy xrays

When an incident electron approaches a positive charged nucleus of a tungsten atom

The incident electron slows down due to electrostatic attraction

Controls the projectile electron energy , intensity, maximum energy and the average energy of the X-ray beam

kvp

Controls the number of projectile electrons striking the anode and the intensity of the X-ray beam

Less than 70 KVp is what % is Brems

100%

Approximately 30-40% of selected KVp

Average keV

Higher KVp =

higher average energy

kvp is your...

energy (quality)

mA is your...

Quantity

Changes in mA and KVp for regarding emission spectrum

Characteristic peak energy levels remain unchanged

Change in KVp regarding emission spectrum

Changes beam amplitude and average energy

Change in generator type

Produce a beam with higher average energy

Characteristic energy produced dependent on

-binding energy of a k shell -tungsten atom is 69.5 keV

aluminum filtration added to xray beam to absorb low energy photons (reduced patient exposure)

Beam filtration

-added to primary beam to alter its intensity(wedge filter or trough filter) -used to image nonuniform anatomic areas -thicker part of filter lines up with thinner part allowing fewer xray photons to reach atomic area

compensating filtration

Value of the photon energy equals to :

The difference of the binding energy of the ionized shell and the transitioning electron

Penetrating ability of the xray beam

xray beam quality

Amount of material required to reduce the X-ray beam intensity to one half its original value

Half value layer

Factors which affect beam quality

-kvp -filtration

Changes the beam quality by changing photon wavelength and an increase causes both the average and maximum energy to increase

kvp

Factors which affect beam quality and quantity

KVp, mA , time, filtration, X-ray circuit waveform

Brems interaction in order:

1. High speed incident electron comes close to the nucleus of a tungsten atom 2. Positive nuclear force field causes the incident electron to change direction 3. The high speed electron decelerates 4. The lost kinetic energy is converted to an X-ray photon

Characteristic intersection in order :

1.High speed projectile electron passes near a K or L shell electron or a tungsten atom 2. The incident electron ejects the inner shell electron 3. A vacancy is created in the orbital shell 4.The unstable atom attempts to return to the normal state by filling the vacancy with the outer shell electrons 5. The movement of outer shell electrons creates a characteristic cascade 6. The potential energy of each orbital electrons movement is converted to a characteristic photon

Energy or motion, type of energy exhibited by incident electrons

kinetic

what happens to the kvp when the frequency decreases, energy decreases, and wavelength increases

kvp decreases

What happens to the kvp when frequency increases, energy increases and wavelength decreases

kvp increases

what happens to the number of photons when exposure time is increased

number of xray photons increase