MITS402R - X-Ray Production Objectives (Chapter 10)

What type of electrons hit the target and transfer their kinetic energy to the target atoms?

Projectile electrons

What do projective electrons interact with?

 Orbital electrons or nuclear field of target atoms

Where do incident (projective) electrons come from?

 Thermionic emission in the electron cloud

Total kinetic energy is equal to?

 KE = ½ mv²

Energy is ____ to mass

proportional

Energy increases by the ____ of the velocity?

Square

Electrons emitted from the filament must accelerate and acquire extreme amounts of KE before reaching the anode which means that high ___ of electrons is required

velocity

What type of interactions are in the x-ray tube target between the incident electrons and the anode target atoms?

 Bremsstrahlung and characteristic

What type of interactions occur in the body and between the x-ray photons and tissue atoms?

Photoelectric, coherent, compton, pair production, photodisintegration

What type of radiation occurs as the incident electron approaches the target (nucleus) and slows down/brakes as the strong nuclear field attracts it and diverts it from its original path

Bremmstrahulung radiation

In bremmstrahulung the electrons slows, changes ____ and radiates energy in the form of a ___

direction, photon

The result of a bremmstrahulung interaction is a loss of ___ energy which is emitted as a ___

kinetic, x-ray photon

High energy bremmstrahulung x-ray photons occur ____ to the nucleus  which causes more loss of energy due to more ___

closer, braking 

Low energy bremmstrahulung x-ray photons are ___ from the nucleus and loss less ___

farther, energy

Bremmstrahulung occurs at __ kV settings

all

What type of radiation provides the heterogenous or polyenergetic nature of x-rays?

Bremmstrahulung

What does heterogeneity of bremmstrahulung radiation contribute to?

 Differential absorption (subject contrast)

Higher numbers of x-rays in bremmstrahulung radiation are produced at ___ energies

 lower

In bremmstrahulung radiation the average kV is roughly ___ of the set kVp

 ⅓

A wide range of energies creates __ variance in subject contrast

high

In bremmstrahulung radiation the photon energy is the exact difference between the ___ energy of the entering exiting ____ electron

kinetic, filament

What type of radiation occurs when an incident electron interacts with an inner shell orbital electron of the anode target atom?

Characteristic radiation

In characteristic radiation the incident electron energy is ____ than the binding energy of orbiting electron

 greater than or equal to

In characteristic radiation the incident electron knocks out the inner shell electron from the orbit and creates a hole which ____ the atom

ionizes

As a result of characteristic radiation the outer shell electron must drop into the hole created by the incident electron and give up its ___

potential energy

In characteristic radiation, energy is released as?

 Characteristic x-ray photon

The characteristic photon energy is equal to the difference between the?

 Binding energy of the electron shells involved 

In characteristic radiation, any outer shell electron can fill an inner shell vacancy the most likely to fill the vacancy is the ___ shell

adjacent

What emitted characteristic photons are useful in our diagnostic beam?

 k-shell

To get k-characteristic emissions __ kV is needed because the binding energy of tungsten is?

70, 69keV

What type of radiation makes up the majority of photons?

bremmstrahulung

What type of radiation makes up a small percentage of the x-ray beam?

Characteristic

What type of radiation high energy created to penetrate through the patient?

Characteristic

The primary radiation is made up of ___%  bremmstrahulung and ___% characteristic

 90, 10

What is the “white” polyenergetic radiation that has a continuous range of energies and wavelengths?

Bremmstrahulung

What type of radiation has limited and discrete energies and wavelengths?

Characteristic

___ is the number of x-rays in the useful beam or absorbed dose

quantity

X-ray quantity (intensity) is measured in?

Milligray in air (mGy_a)

Ionization of air ___ as the number of x-rays in the beam increases

increases

___ is the energy of the radiation or its penetrating ability

quality

As the energy of the x-ray beam is increased the penetrability is ____

increased

Quality of x-rays is defined as their penetrating ability which is determined by their?

 Energy

X-rays with high penetrability are ___ quality x-rays

high

X-rays with low penetrability are ___ quality x-rays

low

“Hard” x-rays are ___ energy photons with __ penetrating ability

 higher, high

How are hard x-ray beams obtained?

1. Higher kVp

2. High atomic number which filters and absorbs the less/low  penetrating x-rays

“Soft” x-rays are ___ energy photons with ___ penetrating ability

 lower, low

How are soft x-ray beams obtained?

1. Lower kVp

2. Lower atomic numbers which let through more of the lower/less energy photons 

If the Z number of the target material increases than the efficiency of the x-ray production ___?

Increases

As the X number of target material increases the binding energies of the shell electrons ___?

Increases

What is the number of electrons freed up from thermionic emission?

mAs

X-ray quantity is ___ proportional to mAs

directly

An increase in mAs ___ quantity

increases (allows more xrays to be produced at the same energy level)

An increase in mAs ___ quality

does not affect (energy level/ penetrability does not increase)

What is a device that removes low energy x-rays while allowing higher more penetrating x-rays to emerge?

Filter

The thicker the filter the ___ its atomic number which produces a ___ beam 

higher, harder

Adding filtration to the useful x-ray beam reduces?

Patient dose

What material is the filter made out of?

1-3mm aluminum

What are the types of filtration?

Inherent filtration, added filtration, compensating filters

What type of filtration is required for tube construction but doubles as a filter?

 Inherent filtration

What part of the x-ray tube acts as the inherent filtration?

glass/metal envelope, insulating oil, protective housing window

What type of filtration is specifically added as aluminum to reduce patient dose?

Added filtration

What type of filtration evens out exposure depending on anatomic part imaged?

Compensating (wedge) filters

An increase in thickness filtration ____ the quantity of x-rays and ___ average energy of x-rays (quality)

decreases, increases (max energy does not change only avg energy!!!)

How does added filtration increase the quality of x-ray beams?

Removes low energy x-rays that have no chance of getting to the IR

Added filtration results in ___ Half value layer (HVL)

increase

An increase in kVp ___ penetration and quality of the x-ray beam

increases

Higher kVp results in an ____ quality

increase

Higher kVp results in an ____ quantity

Increase

X-ray quantity is proportional to?

kVp²

When kVp is doubled the x-ray intensity increases by a factor of

4

When mAs is constant an increase in kVp of 15% ___ the exposure

doubles

When mAs is constant a decrease in kVp of 15% ___ the exposure

halves

An increase in kVp increases… average energy, quantity, quality, exposures 

X-ray production is more efficient at ___ voltages

higher

Both x-ray quantity and quality ____ with high power generators as the ripples factor of the voltage waveform ____

increases, decreases

Compared to a single phase generator, high powered generators will increase?

Quality and quantity