Xray Tube, Production & Emission

Question 1

Tube Housing/Protective Housing

Answer 1

Metallic housing usually lead lined which protects tube, absorbs unusable X-ray, protects from unnecessary radiation and electrical shock risk. Contains oil

Question 2

Primary Beam/Useful Beam

Answer 2

Polyenergetic in nature, exists in a variety of strengths from 1kv to kvp

Question 3

Tube window

Answer 3

Where the primary beam exists in the tube housing

Question 4

Leakage Radiation

Answer 4

radiation that leaves the tube housing at a point other than the tube window

Question 5

glass envelope of the X-ray tube

Answer 5

maintains a vacuum within

Question 6

cathode

Answer 6

the negative side of the X-ray tube whose function is to emit electrons

Question 7

filament

Answer 7

thightly wound coil, most xray tubes are dual focus (2 filaments), only one is used at a time

Question 8

thermionic emission

Answer 8

electron emission from a heated source

Question 9

filament current

Answer 9

the current supplied to the filament for heating

Question 10

focusing cup

Answer 10

metallic cup that encases the filaments, composed of nickel or molybdenum; given a negative charge

Question 11

millamperage

Answer 11

the number of electrons thermionically emitted per second

Question 12

space charge/electron cloud

Answer 12

the collection of electrons “hovering” off the filament

Question 13

anode

Answer 13

the positive side of the X-ray tube

Question 14

rotating anode

Answer 14

anode capable of higher technical factors, anode disk rotates during exposure which spreads out heat over a larger area

Question 15

stationary anode

Answer 15

lower technical factors, anode stationary as electrons impact to produce xray

Question 16

target of anode

Answer 16

the point on the anode where the electrons strike

Question 17

properties of tungsten that make it great for use in xray

Answer 17

high melting point (3422*c)
high atomic number (74)
good conductor of heat
good conductor of electricity

Question 18

rotor

Answer 18

rotates, located inside the glass envelope, connected to the disk by the shaft of molybdenum.
can be noisy and continue to spin long after exposure

Question 19

stator/induction motor

Answer 19

turns the anode disk, located on the outside of the glass envelope and tube housing.
no physical contact between the stator and anode, electromagnetism.

Question 20

true/actual focal spot

Answer 20

the area of electron impact

Question 21

effective focal spot

Answer 21

the true focal spot projected towards the patient

Question 22

line focus principle

Answer 22

the effective focal spot will always be smaller than the true/actual focal spot

Question 23

angle of anode

Answer 23

usually 7-15; 12 is standard

Question 24

anode heel effect

Answer 24

the construction of the anode results in a disparity of X-ray intensity from cathode to anode. More X-rays on the cathode side versus the anode side

Question 25

central ray

Answer 25

the portion of the X-ray beam that is directed tower the center of the film or object being imaged

Question 26

off focus radiation

Answer 26

X-rays produces by stray electrons that interact at positions on the anode at points other than the focal spot

Question 27

heat units

Answer 27

kvp x mas x rectification factor

Question 28

methods of heat transfer

Answer 28

conduction, convection, radiation

Question 29

conduction

Answer 29

the transfer of heat through a material by touching or physical contact of solid objects

Question 30

convection

Answer 30

the transfer of heat by the mixing of molecules in a liquid or gas

Question 31

radiation

Answer 31

the transfer of heat by the emission of infrared radiation

Question 32

dielectric oil in X-ray tube function

Answer 32

absorbs unusable cry energy, electrically insulates, conducts heat away from the X-ray tube

Question 33

xray tube rating charts

Answer 33

designed for specific manufacturer and tube design, based upon anode speed, angle, voltage rectification. used to ensure heat limits not exceeded

Question 34

anode cooling charts

Answer 34

used to prevent damage to the anode by allowing it to cool sufficiently between exposures, shows how long it takes to cool from its max heat level

Question 35

3 things for X-ray production

Answer 35

source of free electrons, acceleration of free electrons, abrupt halting of high speed electrons

Question 36

characteristics of high speed projectile electrons include

Answer 36

have mass (small); negative charge; moving at high speed; possess massive kinetic energy

Question 37

characteristic of tungsten atoms include

Answer 37

high melting point, good conductor of heat/electricity, high atomic number (74)

Question 38

electron binding energy

Answer 38

unique characteristic of elements, measurable, no elements have the same binding energy values

Question 39

electron binding energy varies by

Answer 39

atomic # and distance from nucleus

Question 40

Tungsten shell levels

Answer 40

``` K=69.5 L=12.1 M=2.8 N=0.6 O=.008 P=0 ```

Question 41

kinetic energy

Answer 41

the energy an object in motion possesses

Question 42

KE=1/2mass x velocity2

Answer 42

kinetic energy equals one half mass times velocity squared

Question 43

projectile/incident electrons

Answer 43

electrons moving a a high level of speed from cathode to anode by kilovoltage

Question 44

beam quality/penetrability

Answer 44

the average X-ray strength in the polyenergetic primary beam

Question 45

beam quality/penetrability is controlled by

Answer 45

KVP (primary) and filtration (as filtration goes up, so does beam quality)

Question 46

beam quantity

Answer 46

the number of X-rays in the polyenergetic primary beam

Question 47

beam quantity is controlled by

Answer 47

MAS (primary); KVP; Filtration (as filtration goes up, beam quantity goes down)

Question 48

beam filtration

Answer 48

anything between the focal spot and the patient, can be gas, oil, plastic, mirror, air, etc

Question 49

inherent filtration

Answer 49

built into tube and housing

Question 50

added filtration

Answer 50

between housing and patient

Question 51

total filtration

Answer 51

inherent + added filtration

Question 52

minimum total filtration

Answer 52

at least 2.5mm Al/Eq

Question 53

Filtration is measured in

Answer 53

Aluminum Equivalence

Question 54

half value layer

Answer 54

the amount of filtration required to reduce beam intensity to half its original value

Question 55

As filtration increases

Answer 55

beam quality increases

Question 56

As filtration increases

Answer 56

beam quantity decreases

Question 57

the 1/3rd rule

Answer 57

the majority of X-rays created in the polyenergetic primary beam will have an energy value that is approximately 1/3 of the set KVP

Question 58

differential absorption

Answer 58

different materials absorb X-ray energy to differing degrees

Question 59

Bremsstrahlung Interaction

Answer 59

Braking: A high speed/high kinetic energy electron enters a tungsten atom. The (-1) charged electron is magnetically attracted to the (+74) nucleus. Of a result, the incident electron slows down (brakes)and changes course. The lost kinetic energy changes form into X-ray energy - unpredictable amount.

Question 60

How is the strength of Brems X-ray determined

Answer 60

The X-ray created is exactly equal to the amount of kinetic energy lost.

Question 61

Continuous emission spectrum

Answer 61

A spectrum having no lines or bands | Distributed over an uninterrupted range of wavelengths

Question 62

Characteristic Interaction

Answer 62

Collision: High speed/kinetic energy electron enters a tungsten atom. There is a collision with one of the orbital electrons. If electron possesses greater energy than the orbitals, the orbital is ejected from its orbit leaving a hole. An outer shell electron will jump across the space to fill the hole. The electron she'll transfer results in the transfer of energy, X-ray. The strength of the X-ray is exactly equal to the difference in the orbital ring binding energies involved in the interaction. Only k she'll interactions produce useful X-ray, predictable.

Question 63

Characteristic cascade

Answer 63

movement of electrons from outer shell to inner shell electrons

Question 64

how is the strength of a characteristic X-ray determined

Answer 64

The difference in orbital ring binding energies involved in the interaction.

Question 65

discrete emission spectrum

Answer 65

A spectrum in which the component wavelengths constitute a discrete sequence of values rather than a continuum of values.

Question 66

xray emission spectrum

Answer 66

A set of X-ray frequencies emitted by a target in an X-ray tube.

Question 67

Inverse Square Law

Answer 67

Any physical law stating that a specified physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity

Question 68

Xray intensity

Answer 68

KVP and filtration

Question 69

Polyenergetic/Heterogenous

Answer 69

X-ray energy exists in a variety of strengths from 1kv to the set KVP

Question 70

mGya (mR)

Answer 70

?????????

Question 71

Milliampere-seconds

Answer 71

(mAs) | The number of electrons in motion = the number of X-rays produced

Question 72

Kilovolt Peak

Answer 72

(KVP) | The strength of electron acceleration = the strength of X-rays produced

Question 73

compensating filter

Answer 73

A simple or complex system of placing a discretionary metal filter (usually aluminum) in front of the collimator in order to reduce a portion of the primary beam to compensate for varying body part thickness in the same field of view.