Fdi Tri 1

Front 1

Which is the innermost shell?

Back 1

K shell

Front 2

Outer electrons have higher potential energy. True or False?

Back 2

True

Front 3

What is the name of the energy needed to remove an electron?

Back 3

Binding energy

Front 4

Electrons occupying inner shells have lower binding energy?

Back 4

False

Front 5

What is the minimum amount of Aluminum necessary to reduce patient dose form soft radiation?

Back 5

2.5mm of Al

Front 6

Flow of electrons in one direction?

Back 6

DC current

Front 7

AC is changed to DC in a process called?

Back 7

Rectification

Front 8

What has 100% ripple?

Back 8

Full wave

Front 9

Full wave will produce two times the electrons produced by single half wave?

Back 9

False
3 phase machine? 3% ripple

Front 10

Discovery of x-rays?

Back 10

11-8-1895

Front 11

Name of the first x-rays?

Back 11

Crooke’s tube

Front 12

In crooke’s tube, light emanated from a nearby plate coated with ________?

Back 12

Barium platinocyanide

Front 13

Roentgen awarded Nobel prize in 1901 for Chemistry?

Back 13

No. for physics

Front 14

He died in 1923 of colon cancer?

Back 14

Yes

Front 15

Who was the first person to die of exposure to radiation (1904)?

Back 15

Clarence Dally

Front 16

X-rays are electromagnetic radiation?

Back 16

True

Front 17

Electrons are packets of bundles of photons?

Back 17

False

Front 18

X-rays produce chemical and physical changes because of ionization?

Back 18

True

Front 19

X-ray obey inverse square law?

Back 19

divergent property of x-ray

Front 20

X-rays have wave/particle dual nature?

Back 20

True

Front 21

Which have shorter wave length?

Back 21

Gamma rays

Front 22

X-rays, microwaves and gamma rays are ionizing radiation?

Back 22

False, not microwave

Front 23

The unit that defines absorbed dose equivalence for man is the ___?

Back 23

Rem

Front 24

Electromagnetic radiation is electric disturbance traveling at the speed of light?

Back 24

True

Front 25

Radiation from tube housing?

Back 25

Primary radiation

Front 26

Tube housing is required to allow no more than ____ of leakage radiation to escape when measured at 1 m from the source.?

Back 26

100mR/hr

Front 27

Glass envelope used for?

Back 27

Vaccum

Front 28

not part of the negative terminal inside the x-ray tube?

Back 28

Anode

Front 29

structure made of nickel?

Back 29

Focusing cup

Front 30

substance blended with tungsten?

Back 30

Thorium

Front 31

the average degree of rotation of the anode?

Back 31

12 degrees

Front 32

physical area where electrons strike the anode?

Back 32

Actual focal spot

Front 33

what is affected by the anode angle?

Back 33

Actual and effective focal spot (both0
in heel effect, which side has less photons? Anode

Front 34

automatic exposure is also known as?

Back 34

Phototiming

Front 35

patient measurement determine the ___ needed for diagnostic imaging?

Back 35

mAs

Front 36

Advantage of AC vs manual control?

Back 36

Reduction of repeat film

Front 37

Responsible of quality of x-ray beam?

Back 37

Kvp

Front 38

Manipulates film density?

Back 38

mAs

Front 39

relationship of density and mAs?

Back 39

Linear

Front 40

Not related to Brehmsstrahlung radiation?

Back 40

Inner shell electrons

Front 41

the energy of characteristic radiation during production of x-rays is uniform?

Back 41

False

Front 42

What dominates in the production of x-rays?

Back 42

Heat 99%

Front 43

electron penetrability is cause by the speed of the electrons?

Back 43

True

Front 44

photoelectricity?

Back 44

I could not copy this question

Front 45

the percentage of Compton interactions increase is we increase the kvp?

Back 45

True

Front 46

Classic scatter involves ______ energy photons?

Back 46

Low energy photons

Front 47

Patient Size:
Increase Thickness of Patient =

Back 47

Increase Scatter

Front 48

How does Scatter, Fog and Contrast relate to each other?

Back 48

Increase Scatter = Increase Fog = Decrease Contrast

Front 49

How do you controlling Scatter using X-ray settings?

Back 49

Controls Beam Energy
Restrict kVp settings (between 70 – 90 kVp)
Increase kVp = Decrease Absorption = Increase Scatter

Front 50

Beam Limitation Device used for?

Back 50

Controls Field Size
Use of Collimators
Use of Aperture Diaphragms (simplest)

Front 51

How can compression Device or Technique Controls patient size?

Back 51

Straps can be used to compress the patient
Patient recumbency (lying the patient flat and let gravity flatten them out)

Front 52

Describe how can air Gap Technique be used.

Back 52

Gap between patient and film allows scattered photons to miss the film.
Increase OFD = Decrease Scatter
Grids (Placed after the patient, but before the film)
Grids are made of lead strips so they will reduce the amount of photons reaching the film. The presence of a Grid forces the radiographer to increase mAs therefore increasing patient dosage.

Front 53

What are the grid types?

Back 53

 Linear grids – parallel strips of lead
 Crossed grids – cross-hatched lead strips (No angling of tube possible)
 Focussed grids – angled lead strips with a common convergent point (grid focus point)
Grids increase contrast on film by decreasing scatter radiation.

Front 54

Grid Ratio =?

Back 54

Height / Distance

Front 55

X-ray Films must be?

Back 55

Photosensitive (respond to specific wavelengths of light)
Note: Visible light exposes film, much better than x-rays can.

Front 56

What are the two layers of Film Construction?

Back 56

 Base (supportive layer)
 Emulsion (radiosensitive layer)
Base:
-made of Polyester and Blue dye (easy on the eyes) which gives the film an optical density of about 0.15 before it is even exposed.
Emulsion:
-made of a water soluble gelatinous matrix of Silver Halide Crystals, specifically Silver Bromide (AgBr).

Front 57

What is file speed referred to?

Back 57

Sensitivity
This means how fast the film responds to the photons. Speed is determined by:
 Emulsion thickness (thicker the faster)
 Size of the AgBr Crystals (larger the faster)
 Bi-layer vs. single layer emulsion

Front 58

What is Spectral Response?

Back 58

Sensitivity of the film to different wavelengths of light.
Screen films are usually responsive to blue, green and U.V. light.

Front 59

What is Spectral Matching?

Back 59

matching the film with the screen that emits light of a wavelength that the film is most responsive to. (Blue responsive film with Blue light emitting screen)

Front 60

In order for the Screen to emit light, what must happen?

Back 60

The photon must not pass completely through the screen, it must be absorbed by the screen. Once absorbed, the screen will emit light depending on the energy of the photon.

Front 61

When is the screen is most active?

Back 61

When the photon has slightly more energy than the K-shell electrons of the phosphor crystals in the screen. This is the basis of the K-edge phenomena. The average energy of diagnostic x-rays are closer in energy to the K-shell of Rare Earth Crystals than for Calcium Tungstenate.
For this reason Rare Earth Emits more light when diagnostic X-rays are used.

Front 62

What is file density?

Back 62

Film Density:
- the blackness on the film.
- measured by the densitometer
Order of increasing film density = Metal, Bone, Water, Fat and Air.

Subject Density
- how tightly packed the subject material is (e.g. fat vs. bone)
Order of increasing subject density = Air, Fat, Water, Bone and Metal.
Note: Subject Density is the exact reverse of Film Density

Front 63

What is film contrast?

Back 63

Film Contrast:
- the difference in optical densities between successive areas on a film
- the bigger the difference, the higher the contrast, the shorter the gray scale (Black & White)
Subject Contrast:
- the difference in attenuation between different types of materials in the subject (Lung vs. Bone)
- the more noticeable the difference on the film, the higher the subject contrast, the longer the gray scale

Front 64

High film contrast =?

Back 64

Short gray scale on film

Front 65

High subject contrast =?

Back 65

Long gray scale on film

Front 66

Subject Contrast is the exact reverse of Film Contrast.
True or False?

Back 66

True

Front 67

High kVp =?

Back 67

Low Film Contrast = High Subject Contrast = Long Gray Scale

Front 68

Low kVp =?

Back 68

High Film Contrast = Low Subject Contrast = Short Gray Scale

Front 69

Latitude is a measure of ?

Back 69

Film Contrast
- the range of optical densities for which the film is responsive (e.g. 0.5 – 2.5)
- the wider the range, the wider the latitude, the longer the possible gray scale

Front 70

Wide Latitude =?

Back 70

Low Film Contrast

Front 71

Narrow Latitude =?

Back 71

High Film Contrast (little forgiveness or room for error)

Front 72

What is a Step – up transformer?

Back 72

Transformer with a turn ratio (# of turns in secondary coil) > 1
More windings in 2ndary coil
↑ voltage
↓ amperage
frequency stays the same

Front 73

What is a Step – down transformer?

Back 73

Transformer with a turn ratio < 1
More windings in primary coil
↓ voltage
↑ amperage
frequency stays the same

Front 74

What is Ripple factor?

Back 74

Voltage that shows no fluctuation from its maximal amplitude
Single wave – RF = 100% - voltage goes from 0 to maximum with each cycle
Triple phase – RF = 3-14% - 3 separate AC current sources
High frequency – RF = almost 0% single source of AC current uses microprocessor to generate almost pure DC current

Front 75

Parts of xray machine

Back 75

Parts of xray machine

Front 76

describe the Cathode (-).

Back 76

High amperage filament circuit provides free electrons
Filament (thoriated tungsten, long/short), focusing cup (nickel)
Space charge and Edison effect occurs here

Front 77

What does High voltage do?

Back 77

Causes free electrons to accelerate across the gap

Front 78

Electric potential energy -->?

Back 78

Kinetic energy of electrons

Front 79

Describe the Anode side.

Back 79

Electrons collide or interact with atoms here and some kinetic energy is converted to EM energy (xrays)
Stationary / rotating
Focal spot (see below this question)
Tungsten – Rhenium
Anode heel effect
**use tungsten b/c high temp and high atomic #**

Front 80

What does the casing (tube housing) do?

Back 80

Keeps scatter radiation from leaking out

Front 81

What does the Insulating oil do?

Back 81

Heat dissipation and cushion

Front 82

What are the types of focal spots and where they are found?

Back 82

Actual focal spot and effective or projected focal spot

Front 83

Actual focal spot

Back 83

Where the electrons actually strike the anode

Front 84

Describe the effective or projected focal spot.

Back 84

How the actual focal spot appears from the perspective of the film
**what you see on the film**
-this focal spot appears smaller than the actual focal spot due to the line focus principal
-dependent on the size of the actual focal spot and the anode angle
-smaller anode angle (↑’s heel effect) → smaller the effective focus

Front 85

Types of timers?

Back 85

Synchronous, impulse, electronic, mechanical, mAs, anatomically programmed, AEC

Front 86

What is Synchronous?

Back 86

On older units, uses small electric motor which rotates @ 60 RPS
Accurate down to 1/20 sec
Min possible exposure 1/60 sec

Front 87

What is Impulse?

Back 87

Measure impulses instead of time
Usually paired with synchronous
1/120 and 1/20 sec

Front 88

What is Electronic?

Back 88

Most commonly used
Accurate down to 1/1000 sec
2 types: resistor/capacitor and microprocessor

Front 89

Describe mAs.

Back 89

Operates on the basis of mAs sent through the tube, electronically measured
Simplifies but takes away flexibility

Front 90

What is Anatomically programmed?

Back 90

Digital microprocessor in control panel is pre-programmed to deliver proper technique for a particular exam
Operator only to set kVp and mA

Front 91

What is Automatic Exposure Control (AEC)?

Back 91

Radiation detector which measures amound of radiation that has passed through patient then terminates when pre-determined amount reached
Types : ion chamber and photodetector

Front 92

mA is used to…?

Back 92

Measure tube current

Front 93

What are the X-ray production types?

Back 93

Bremsstrahlung radiation, Characteristic radiation, Excitation

Front 94

Describe Bremsstrahlung radiation.

Back 94

Brems, braking, general or white radiation
Involves the nucleus
NOT Ionizing!
Most common
Polyenergetic beam, most effected by filtration, low energy film
Atom closer to the nucleus  higher energy emitted in form of photon

Front 95

Characteristic radiation

Back 95

Involves k shell – being most impt.
Kicking electrons out
Higher the atomic # the higher the energy
Each orbit yields own specific energy of xray
K shell binding energy – 69.5%
L shell binding energy – 12.1%

Front 96

Excitation

Back 96

99% of electrons that bombard target  excitation of tungsten atoms
Excited to higher energy level and emit heat and light when return to original level

Front 97

Anode heel effect

Back 97

Absorption at the anode
Uneven distribution of radiation form cathode side to anode side of the xray field
↑in radiation at the cathode end (also ↑ penumbra)
↓in radiation at the anode end
Inverse relationship exists between anode angle and amount of heel effect
Inverse relationship exists between FFD and amount of heel effect
Tilt ~ 6.20 degrees

Front 98

Most common cause of tube failure

Back 98

Evaporation of tungsten onto glass causes a filtering of the xray beam

Front 99

Photon interactions with matter

Back 99

Classic, Photoelectric, Compton, Pair Production, Photodisintegration

Front 100

Classic

Back 100

Diagnostic – electron interaction
Classical scatter, Rayleigh scatter, Thomson scatter or unmodified scatter
Non-ionizing
Occurs when a low energy xray strikes an orbital electron and causes it to vibrate
Only changes Direction of xray photon

Front 101

Photoelectric

Back 101

Diagnostic – electron interaction
Complete absorption
Interaction btwn an incident electron or xray photon and inner shell electrons of target atom
Most dominant in diagnostic range

Front 102

Compton Scattering?

Back 102

Diagnostic – electron interaction
Incoherent
Most Common
Most detrimental to film
Incident xray strikes and outer shell electron and ejects it from its orbit
Produces recoil electron

Front 103

Types of filtrations?

Back 103

Inherent, Added, compensation

Front 104

Inherent filtration?

Back 104

Results from attenuation of xray beam from the tube envelope
Glass from beam attenuates beam similarly to aluminum
Increases as the age of the tube increases  vaporization of filament onto to tube
Ex. Lead lining, oil, glass
(↑ patient dose)
(↓ quality)

Front 105

Added filtration?

Back 105

Any attenuators placed in the beam
Alters the effective energy and the intensity distribution of the xray beam by selection of specific energy ranges
Aluminum is most common type but also use copper and plastic (acrylic)
Collimator
Contributes to patient dose only (↓)
↑ quality

Front 106

Compensation filters?

Back 106

Selective
Place in the beam to modify xray filed distribution, compensating fro wide variations in patient thickness

Front 107

Total Filtration?

Back 107

2.5 mmAl for machines operating above 70 kVp = inherent + added

Front 108

Intensifying screensis used for what?

Back 108

Used to increase efficiency and decrease patient exposure
Convert energy of xray beam into visible light
~ 30% of the xrays striking and intensifying screen will interact with the screen
2 per cassette
has emulsion on both sides to increase efficiency

Front 109

Protective coatingof the film?

Back 109

Layer closes to film, helps protect during handling, helps eliminate buildup of static electricity, provides a surface for routine cleaning, transparent to light

Front 110

Phosphor layer of the film?

Back 110

Active layer
Emits light during stimulation by xrays – converting energy of xray beam into visible light
Calcium tungstate – conventional phosphor used
Rare earths – more efficient – Gadolinium, Lanthanum, Yttrium
Phosphors should have:
-High atomic number
-Emit large amount of light per absorption of xray photons – conversion efficiency
-Spectral emission of screen must match the sensitivity of the xray film – spectral matching
-Should not be affected by heat, humidity, or other factors

Front 111

Reflective layer of the film?

Back 111

Only present in Ca tungstate
Redirects light headed in other directions to the film therefore increasing efficiency

Front 112

Base layer of the film?

Back 112

Serves as a mechanical support for the active phosphor layer – made of cardboard or polyester

Front 113

What is Luminescence?

Back 113

Light emission by the phosphor layer
Two different processes:
Fluorescence and phosphorescence

Front 114

What is Fluorescence?

Back 114

Light emitted promptly then stops

Front 115

What is Phosphorescence?

Back 115

Results in a delayed emission of light causing and afterglow or lag

Front 116

Screens affect on patient dose by?

Back 116

Screens decrease patient dose by increasing efficiency of film production

Front 117

Spectral matching?

Back 117

Two intensifying screens per cassette – one in front and one in back

Front 118

Wire mesh test?

Back 118

Used to test for screen contact
Close contact should be maintained between screen and film to guarantee sharpness

Front 119

Film layers?

Back 119

Base, Adhesive, Emulsion

Front 120

Base layer?

Back 120

Provides support for the fragile photographic emulsion
Made of 2 mm of polyester plastic –tinted blue to reduce glare

Front 121

Adhesive layer?

Back 121

Gelatin to hold emulsion to the base

Front 122

Emulsion layer?

Back 122

Image forming portion of the film
Made of Silver halide crystals
Supercoating – protects emulsion – closest to film

Front 123

Silver halides?

Back 123

Silver Bromide – (90%-99%)
Silver Iodide – (1%-10%)

Front 124

Types of films?

Back 124

Screen, Direct exposure, Duplicating

Front 125

Screen functions?

Back 125

Used with cassettes that intensifying screens which emit light when exposed to radiation – film most sensitive to color of light emitted

Front 126

Direct exposure film?

Back 126

Thicker emulsion than screen film to trap more x-rays

Front 127

Duplicating film?

Back 127

Duplicates an existing radiograph. Single emulsion

Front 128

Film latitude?

Back 128

Range of exposures over which x-ray film will respond with optical densities in the diagnostically useful range
Wide latitude – wide gray scale
Narrow latitude – short gray scale
Latitude and contrast inversely proportional
**Remember high contrast – low KVP – short grayscale; low contrast – high KVP – long graysclae

Front 129

Film speed?

Back 129

Ability of x-ray film to respond to x-ray exposure
Exposure of < 1 mR can be detected with film-screen combinations (several mR needed for direct-exposure film to produce measurable response
Fast films curves positioned to the LEFT of slow film curves along relative exposure film
Xray films characterized as fast or slow according to sensitivity to x-ray exposure
i.e. if film A 2x as fast as film B – film A would require only ½ mAs req’d by film B to produce given optical density (also A maybe of lesser quality b/c of noise)

Front 130

Contrast?

Back 130

Sharp differences in optical density (OD) is high contrast
Less distinct OD differences is low contrast
Radiographic Contrast product of two things:
-film contrast (inherent in film and influenced by processing)
-subject contrast (determined by size, shape and xray attenuating characteristics)
OD’s should lie btwn .5 – 2.5
Contrast outside range is lost in the toe or shoulder of the characteristic curve

Front 131

Solarization?

Back 131

Film acts opposite to the way it should

Front 132

Photographic density?

Back 132

Aka optical density
Measurement of film blackness
Expressed as D=log(Io/It)
D= density, Io= light incident on a film, It= light transmitted by the film, Io/It measures the opacity of the film (ability of the film to stop light)

Front 133

Radiographic density?

Back 133

Subject contrast
ability of a biologic substance to transmit or absorb x-ray photons
relates to photoelectric effect
Radiolucent / radio-opaque

Front 134

Radio-lucent?

Back 134

Do not absorb many x-ray photons
Most incident photons transmitted to the film – Air, fat
Results in dark radiograph

Front 135

Radio-opaque?

Back 135

Tissue that absorbs (attenuates) a lot xray photons
Most incident photons are abosorbed w/in tissue on only few reach the film to interact with silver – Bone, Muscle
Will result in light radiograph or white portion of film (**hint** think opaque – opal – opal is close to white)

Front 136

Factors that influence intensity of scatter radiation?

Back 136

kVp, field size, thickness, tissue density

Front 137

↓kVp?

Back 137

Reduce production of scatter

Front 138

↓ or limited field size?

Back 138

Reduce production of scatter

Front 139

↓ thickness?

Back 139

Reduce production of scatter

Front 140

Beam restricting devices (advantages and disadvantages of each)?

Back 140

Aperature diaphragms, cones and cylinders, collimators

Front 141

Aperature diaphragms?

Back 141

Simplest type – sheet of lead with hole in center, size and shape of hole determine that of x-ray beam
Advantage: simplicity, lead is soft therefore easily alterable
Disadvantage: produces fairly large penumbra
**have to use fixed SID to get desired image**

Front 142

Collimators?

Back 142

Best all around
Two sets of shutters control beam dimensions
Move together as a unit so that the second shutter aligns with the first to “clean up” penumbra
Shutter function as two adjustable aperature diaphragms
Advantages over other types:
Provides an infinite variety of rectangular x-ray fields
Light beam shows the center and exact configuration of the xray field

Front 143

Positive beam limiting device?

Back 143

PBL – automatic collimators – same as the other collimators except that their shutters are motor – driven
Perfectly aligned collimator will leave an unexposed border on all sides of the developed film

Front 144

Grid?

Back 144

Radiographic accessories designed to minimize the effect of scatter radiation
Not required for extremity projections
Types: focused, parallel

Front 145

Focused grid?

Back 145

Grid made up of lead strip that are angled slightly so that they focus in space
Linear focused grids converge at a line in space called the convergent line

Front 146

Parallel grid?

Back 146

Lead strips are parallel when viewed in cross section
Focused at infinity and do not have a convergent line
Not used anymore

Front 147

Grid ratio and Grid frequency?

Back 147

Ratio between the height of the lead strips and the distance between them
Expressed as two numbers: first is actual ratio and second is always one
Grid ratio = h/D
High ratio grids more effective in cleaning up scatter radiation than low ratio grids because angle of deviation is less than in high than low
Use of grids requires higher exposure factor
Higher grid ratio – higher patient dose
Number of grid stips or grid lines per patient dose
Grids with higher freq. show less distinct grid lines on a radiograph than grid with low frequency

Front 148

Grid cut-off and types?

Back 148

Major disadvantage of grids is increased patient exposure as well as danger of grid cutoff
Require careful centering of xray tube
Grid cutoff is loss of primary radiation
Radiograph is light where cutoff occurs
Greatest w/ high ratio grids and short grid – focus distances
Types: focused grids used upside down, lateral decentering, focus-grid distance decentering

Front 149

↑motion?

Back 149

↑unsharpness
**most detrimental to recorded detail**
**can come from tube, patient or image receptor**

Front 150

Use of intensifying screens?

Back 150

↑penumbra by ↑OID
**film screen combinations are inversely proportional to recorded detail**

Front 151

↑density?

Back 151

↑attenuation

Front 152

↑atomic number?

Back 152

↑attenuation

Front 153

↑amount of material?

Back 153

↑attenuation

Front 154

↑energy of beam?

Back 154

↓kVp

Front 155

Subject contrast?

Back 155

If all photons transmitted→film uniformly black
If all photons attenuated→film would be uniformly white
Size of differential between different tissues attenuation abilities determines the amount of natural contrast in the xray image

Front 156

What is the pupose of the x-ray machine?

Back 156

To convert potential energy to electromagnetic energy in the form of photon.