RVT- Radiography Flashcards
1
Q
What 3 items are used to keep the beam ‘clean?’
A
The filter under the tube
The collimator
The grid under the table
2
Q
What is the source image distance?
A
The distance from where the beam leaves the tube to where it reaches the film
3
Q
By raising the tube head, do we increase or decrease the density on the film?
A
We decrease density, causing the film to be lighter
4
Q
What does the transformer do?
A
Converts the power from one voltage to a higher or lower voltage.
Therefore, increases or decreases the voltage in the circuit
5
Q
The function of the X-ray machine is to convert ________electric energy into _____________energy.
A
Hydroelectric energy
Electromagnetic energy
6
Q
Where is the effective focal spot?
A
The point at which the beam impacts the animal
7
Q
What is the ‘actual’ focal spot?
A
Where the electrons hit the anode
8
Q
Where would we see ‘stationary’ anodes used in radiography?
A
Small portable machines
Dental radiographic machines
9
Q
Where do the filaments sit on the cathode?
A
In the focusing cup
10
Q
A hair dryer converts electrical energy into ________ energy?
A
Thermal energy
11
Q
What medium/material is used for a contrast study?
A
Barium sulfate ( most commonly)
12
Q
How much barium is usually given to a pet for a contrast study?
A
3-6cc per pound
13
Q
How often are X-rays taken with barium protocol?
A
0-15-30-60-120-180mins
14
Q
What is the normal passage of barium through the stomach and colon?
A
Stomach starts to empty by 30min
Barium enters colon by 3 hrs
However, residual barium can be seen in stomach for 3 hrs
15
Q
How can X-ray radiation affect us on a cellular level?
A
Radiation can change our atoms by ‘bumping’ the negatively charged electrons out. Esp affects cells that are rapidly dividing.
16
Q
Why can we not run an X-ray machine directly off power from the wall?
A
The power in most homes and businesses run on an AC -alternating positive and negative charge current that pulses
17
Q
When we double the distance away from the centre beam, how much is our radiation exposure reduced by?
A
1/4
Inverse square law
18
Q
What is the Grid?
A
Under the table to help reduce the radiation scatter on larger animals. Made of radiodense strips of lead placed between patient and plate. Grid ‘captures’ scatter
19
Q
What is the ‘blocker’ on an X-ray film cassette?
A
A small square in the corner of the cassette that is unexposed that can be used to label with a light flasher
20
Q
What are the intensifying screens on a cassette?
A
Sheets of phosphor crystals bound together and mounted on a base inside the cassette
21
Q
How do intensifying screens work?
A
The phosphor crystals convert radiation to light reflecting light into the film.
22
Q
What are the layers of the intensifying film?
A
Protective layer
Emulsion ( phosphor crystals)
Reflective layer
Base
23
Q
To make an identical image, the larger crystals will require what amount of radiation?
A
Less
24
Q
To make an identical image, the smaller crystals will require what amount of radiation?
A
More
25
The detail of the large crystals would be described as?
Less detailed/ more blurry
26
The detail of the smaller crystals would be described as....?
Finer/higher detail
27
'Fast screen' requires a smaller or larger amount of exposure?
Smaller
28
Slow screen requires a larger or smaller exposure?
Larger
29
What is the primary purpose of the intensifying screen?
To reduce the amount of radiation needed to produce a radiograph.
30
Describe quantum mottle?
An artifact seen with fast screens that are very sensitive. Inconsistent fluorescence from the phosphor layer resulting in a spotty moth eaten appearance.
31
What % of the exposure recorded on a film is due to the light emitted from the intensifying screens?
95%
32
Faster screen speeds require a small exposure and produce less detail. Slow screen speeds require larger exposure and produce greater detail. T or F?
True
33
To absorb back scatter, the back of most cassettes are lined with.....
Lead
34
Does the use of intensifying screens affect our decreasing of KVP or mA?
KVP.
35
The main advantage of today's rare earth coated screens is.....
They have a higher X-ray to light conversion efficiency
36
True or false....Non screen film requires greater exposure?
True
37
A processed film that has not been exposed to ionizing or visible light will appear.....
Clear
38
What are the appropriate storage conditions for radiographic film?
```
Cool 10-15 C
Dry
Dark, sealed box/container
Humidity 40-60%
Stored vertically
```
39
What film speed system is most commonly used in veterinary medicine?
Medium speed system
40
What are the type of crystals in the intensifying screen emulsion?
Phosphor crystals
41
What are the layers in the film?
Top coat
Emulsion layer
Adhesive layer
Base x2 or with anti curl layer under base
42
What type of crystals are in the emulsion layer of the film?
Silver halide crystals
43
When taking an radiograph of a long bone, what are our borders?
Joint above and joint below
44
When radio graphing a joint, what should we include in the view to ensure proper positioning?
1/3 of bone above
| 1/3 of bone below
45
Long, gray scale contrast is good for what 2 views?
Abdominal and thoracic
46
What is the name of the instrument used to measure the thickness of an area being radiographed?
Calipers (in cm)
47
What is the difference between a one-time artifact and a repeat artifact?
Repeat is something in the cassette/grid table,
| One-time is specific to that particular radiograph
48
How can you decide if there is adequate penetration on a film?
If you can see the outlines of the organs visualized
49
Name 5 positioning aids?
```
Trough
Foam
Towels
Rope
Gauze
Tape
```
50
What is the latent image on an X-ray film?
The invisible image on a film that has been exposed to radiation but has not been developed yet.
51
In manual processing, what are the contents of the 3 tanks?
Developer, water bath, fixer
52
In film processing, what are the 5 steps in order?
```
Place film in developer tank
Rinse in water bath 30 seconds
Fixer
Water bath for 20 min
Drying rack
```
53
Which size crystal requires more radiation to emit the same amount of light?
Smaller
54
Which crystal would produce a more 'grainy' image
Larger
55
Which crystal would be considered slow?
Small
56
List 4 advantages of automatic processing?
```
Faster
Less handling of chemicals
Less tech time
Easier
Fewer errors
```
57
List the required info that must be on an radiograph
```
Name of pet
Name of Owner
Name of hospital
Date
View
```
58
What do silver halide crystals become after processing?
Black metallic silver
59
At which stage of processing do the silver halide crystals convert to black metallic silver?
In the developer
60
At what stage of processing are the unexposed silver halide crystals removed from the film?
When in the fixer
61
At what stage is the gelatin in the film hardened?
The fixer stage
62
What can cause a series of parallel white lines to develop on the film?
The grid
63
The tendency of a luminescent compound to continue to give off light after the X-ray has stopped is called.....
After glow
64
A device made of lead strips in a spacing material to absorb scatter radiation....
The grid
65
The amount the exposure needs to be increased to compensate for the grids absorption of a portion of the primary beam....
Grid factor
66
If using rare earth screens, what spectrum of light must the film be sensitive to?
Green range
67
Non-screen film would most likely be used to take what type of radiograph?
Dental
68
What was William Crooks famous for?
Inventing a glass tube and a system for evacuating air from it to study energy in a vacuum. Neg charge on one end. Positive on the other.
69
What was Wilhelm Roentgen famous for?
Inventing the first X-ray. Noticed a projection on a wall while using a Crooks tube.
70
In relation to xrays, what is Albert Einstein known for?
Coined the term photons as well as described Xrays as being like a wave and particles
71
What is a photon?
A basic unit of light (no mass, travels at speed of light)
72
What is radiation?
Is the transfer of electromagnetic energy in waves and photons
73
What is electromagnetic energy?
Energy produced by the motion of electrically charged particles
74
What is wavelength?
The distance between two consecutive corresponding points on a wave. Crest to crest or trough to trough
75
What is frequency?
The number of times a wave passes a spot
76
What cells are most affected by radiation?
Rapidly dividing cells like those found in the GI tract, reproductive tract, younger persons and neoplastic cells
77
What is somatic damage?
Damage seen within the lifetime of the person
78
List important ways we can protect ourselves from excess exposure to radiation?
PPP, rotate staff, proper machine maintenance, dosimeter monitoring, stay back from the beam, sedating animal so we can step out or away, proper settings so no extra xrays needed, proper positioning aids
79
What unit of measurement does the dosimeter use?
Millisievert
80
What is the maximum exposure dose allowed for full body per year?
20mSv per year
81
Which electromagnetic radiation are non-ionizing?
Regular sunlight
Infrared
LPF, VLF
Microwaves,
82
Which electromagnetic radiation are ionizing radiation?
UV
Xrays
Gamma Rays
83
Of the xrays produces hitting an anode, what % is an X-ray and what % is heat?
99% heat
| 1% X-ray
84
What is the permissible mSv dose allowed for the eye per year?
150mSv
85
What is the permissible mSv exposure for the public per year?
15mSv
86
What is meant by barrier requirements?
Types of materials used in walls of functioning X-ray room as well as thickness of walls and use of adjacent rooms.
87
What is attenuation?
Decreased intensity of the X-ray beam
| ...the beam can be attenuated by PPP or by cement walls
88
Rare earth emulsions have what % conversion efficiency?
50-60%
89
Calcium tungstate (non-rare earth) emulsion has a conversion efficiency of what %?
30-40%
90
What will be the result on the screen if the wrong colour of film is used with the wrong intensifying screen?
Gray and will lack contrast
91
What do phosphor crystals produce on the film?
Blackness because it is exposing the parts of the film that are Radiolucent.
92
Which film emulsion requires less exposure time?
Rare earth
93
What is the purpose of the protective coating on the intensifying screen?
Prevents static
Provides protection from scratches
Provides a surface that can be cleaned
94
Focal film distance is also known as....
Source Image distance
95
What is the image source distance usually?
40 inches
96
What do the step up and step down transformers do?
Step up increased power to the tube to increased the strength at which the beam leaved the tube...KV circuit
Step down decreased power to the filament/cathode end of the tube to prevent filament from melting. MA circuit
97
What does a rectifier do?
Converts the alternating current AC to a direct current DC
98
What are the 4 methods of labelling film?
Graphite tape
Light flasher
Lead letters
Film identification camera
99
What is the definition of an artifact?
Any accidental or unintentional image on a radiograph
100
What can cause screen artifacts?
```
Over enthusiastic cleaning
Humidity
Scratches/wear
Chem spills
Poor screen contact
```
101
Raised 'pinpoints' on a film can indicate?
The emulsion of the screen has absorbed moisture. Pinpoints are emulsion that do not flash with light
102
The image contrast is good, the subject is still but structures are still blurry. What could cause this?
Poor screen contact
103
What test can we perform to ensure the screen fits tight to the film?
Wire mesh test. Set on top of cassette and take pic. If poor screen contact, the film will have areas that are not sharp.
104
What does a single sided film have that a double sided film does not?
Anti-curl layer under the base
105
What is a colloid?
It is an emulsion that is in liquid form in high temp but solid form in low temp.
106
The higher number of silver halide crystals converted during exposer =
More blackness on the film
107
90% of poor quality films are a result of...
Poor processing!
108
The safelight should be how high above the countertop and should not exceed how many watts?
4 feet
109
Why are red safelight a used instead of other colours?
Red is at the opposite end of the light spectrum to the blues and greens
Safelight colour must be invisible to the X-ray film
110
How do we do a safelight test?
Expose a film- tabletop
Remove film from cassette in dark room
Slide 2/3 of the film under the cassette leaving 1/3 on the countertop under the safelight. Wait 30seconds then uncover the 2/3 and wait another 30 seconds. Develop and look for density change
111
What should the temperature be on the processing tank water?
20 degrees Celsius
112
What does the developer do?
Swells the emulsion in the film converting the sensitized silver halide crystals to black metallic silver
113
A lack of blackness on a film could indicate....?
Developer needs to be changed.
114
What ingredients are in the fixer?
Solvent
Fixing agent to clear remaining silver halide crystals
Acidifier- neutralizes any alkaline developer remaining
Hardener
Preservative
115
What will fixer retention look like on a film?
Brownish color from retained sulphur
| Film will deteriorate quickly
116
What will an X-ray look like if chemistrys are poorly mixed?
Clouds/ wave like
117
What 3 things does a good radiograph require?
Good density, contrast and detail
118
What are the 5 radiographic opacities/densities from most radiolucent to most radiopaque?
```
Gas
Fat
Fluid/soft tissue
Mineral
Metal
```
119
What does the KV control?
Controls the speed and energy of the electron beam
120
What does mA control?
Number of electrons emitted across the tube
121
True or False
| MA blackens or lightens the whole film uniformly?
True
122
Do we want to take X-ray when animal inhaling or exhaling?
Exhaling because it displaces the diaphragm cranially allowing more of the abdomen to be seen
123
What are 3 good preparations for the animal before taking an X-ray?
Fasting 12 hrs previous
Enema 3-4 hrs previous
Sedation
124
How do we adjust the X-ray positioning to see a bladder on a male dog?
VD oblique
125
What is the best view for a heart view...VD or DV?
DV
126
What is the best view for looking at lungs....VD or DV?
VD
127
What steps do we follow when evaluating/interpreting an abdominal radiograph?
```
View in 4 areas
-Extraabdominal structures
-Peritoneal and retro peritoneal space
-GI system
=Urogenital system
```
128
Which apparatus reduces the 'weak/low' kVp Rays coming out of the X-ray tube?
The 'filter' that sits under the tube. It is made up of thin wafers of metal that filter out the weaker rays
