105 x-ray procution and matter interactions flashcards

The inner shell electron that is ejected is called (photoelectric absorption)

Photoelectron

Number of crest or cycles per sec

Frequency

As the vacancies are filled characteristic radiation is also released known as

Secondary radiation

What do the atoms become because of the vacancy left by the ejected e- in photoelectric absorption

Ionized

Who discovered x-rays

Wilhelm roentgen

An x-ray beam consist of x-rays that are related to …

White light , ultraviolet and infrared

How do electromagnetic waves differ?

They differ in wave length

When in the patient it’s

Incident photon

Unit of frequency defined as 1 cycle per second

Hertz

When were x-rays discovered

Nov 8 1895

Gamma rays and x-rays differ in what

Origin

The Q shell has the..

Highest total energy and lowest binding energy

When a 80-100 kV is applied to the tube how much are emitted as brems?

90%

The K shell has the …

Lowest total energy and the highest binding energy

Unwanted densities caused predominantly by scattered photons and less commonly by secondary photons

Radiation fog

The photon which exits the atom in a different direction (Compton scatter)

Compton scattered photon

Characteristic radiation is also known as what?

Discrete radiation

Most of the x-rays produced in the diagnostic range are produced by ?

Brems

An increase in the filament current liberates more electrons per second at the filament (output is directly proportional to the mA)

Tube current

An individual x-ray is a bit of energy called

Photon or quantum

How much of the emitted x-rays are characteristic radiation when the tube potential is in the 80-100 kV ?

10%

Characteristic radiation is produced at tube potential of less than …

69kV

Whenever fast moving electrons undergo rapid deceleration or electron drop from an outer shell to a hole in an inner atomic shell, x-ray are produced

X-ray production

The energy of a photon in characteristic interactions is

A rise in kV increases output because the electrons in the tube are speeded up and produce

more x-ray photons at the target.

The resulting x-ray beam will contain photons of higher energy.

Tube potential

Occurs when a scattered photons deflected back toward the source (Compton scatter)

Backscatter radiation

X-rays are classified as what?

Electromagnetic radiation

Target material has what

High melting point

High atomic number

Tungsten is metal of choice

What is the voltage ripple within a single phase x-ray system?

100%

The ability of an x-ray beam to penetrate matter

Quality

One rule of photoelectric interactions is that a photoelectric interaction is more likely to occur with …

an electron which is more tightly bound

in its orbit.

How are x-rays produced?

Whenever a stream of fast moving electrons suddenly undergo deceleration

What speed do electromagnetic waves such as x-rays travel at ?

3×10^8 m/s or 186,000 miles per second in a vacuum

When in x-ray tube it’s

Incident electron

The output of an x-ray beam may be altered by varying 4 factors:

Tube current

Tube potential

Distance

Filtration

Occurs when an x-ray photon interacts with an inner shell electron

Photoelectric absorption

With single phase equipment the voltage across the x-ray tube

Drops to zero every 180 degrees

Gamma rays are emitted by what ?

The nuclei of certain radionuclides

The beam is hardened due to greater removal of low energy than high energy rays by the filter

Filtration

One basic rule of photoelectric interactions is that incident x-rays photon energy must be…

greater (or similar) than the binding energy of the

inner shell electron

One basic rule of photoelectric interactions is that photoelectric interaction is more likely to occur when..

the x-ray photon energy and the

electron binding energy are nearer to one another.

Where does the 69 kV come from in characteristic radiation?

Comes from the binding energy of the k-shell in a tungsten electron

The removed electron from Compton scatter is called

Compton or recoil e

The useful wavelength in x-rays is about

0.1-0.5 angstroms

Tungsten has a melting point and atomic number of what?

3370 degrees Celsius

74

Occur only when incident electron interacts with inner shell electron

Characteristic interaction

The incident electron knocks out an inner shell electron and the orbiting electrons fill the hole until the outermost shell is missing an electron

Characteristic cascade

Wavelike fluctuations of electric and magnetic fields set up in space by oscillating electrons

Electromagnetic radiation

Occurs when an incident photon interacts with a loosely bound outer-shell electron, removes the

electron, and then proceeds in a different as a scattered photon.

Compton scatter

Occurs only when the incident electron interacts with the force field of the nucleus

Brems

The energy of a photon in characteristic interactions is …

exactly the difference between the binding energy of the outer and inner shells between the electron dropped

The energy in brems is …

exactly the difference between the entering and exiting kinetic energy of the electron

properties of x-ray production

1. Highly penetrating, invisible rays.

2. Electrically neutral.

3. Polyenergetic.

4. Liberate minute amount of heat on passing through matter.

5. Travel in straight lines.

6. Travel at the speed of light

7. Ionizes gases

8. Causes certain crystals to fluorescence

9. Cannot be focused with a lens

10. Affect photographic film

11. Produce chemical and biological changes

12. Produce secondary and scattered radiation

Frequency is inversely proportional to wavelength.

Low kvp = low frequency = long wavelength

High kVp = high frequency= short wavelength

Compton scatter will always

Occur

Looks grainy

Obscures detail

Primary source of tech’s radiation