Test #2 Flashcards
1
Q
What is a technique chart?
A
a way of knowing what to set the exposure to
2
Q
Purpose of technique chart?
A
to provide consistent way of exposure for a diagnostic radiograph
3
Q
Caliper
A
device used to measure the patient for radiograph
always use centimeters
4
Q
Where to measure when doing elbow
A
distal humerus
5
Q
where to measure when doing radius/ulna
A
distal humerus
6
Q
where to measure when doing stifle
A
distal femur
7
Q
where to measure when doing tibia/fibula
A
distal femur
8
Q
How to start a technique chart
A
mesure a medium sized dog/cat for abdominal
Set machine to 2.5mAs & 65 kvp
set shortest exposure time to achieve 2.5 mAs
adjust technique as needed
Always log the techniques!
9
Q
Suggest kVp ranges for extremities
A
55-65kVp
10
Q
Suggest kVp ranges for abdomen
A
65-85kVp
11
Q
Suggest kVp ranges for thorax
A
75-95kVp
12
Q
Suggest kVp ranges for pelvis
A
55-75kVp
13
Q
Factors to consider when developing a technique chart
A
tissue thickness
screen type
grid factor
14
Q
Primary beam
A
a group of rays that make up beam
15
Q
Central ray
A
most central ray
part of primary beam
16
Q
Primary rays
A
the rays on either side of central ray
part of primary beam
17
Q
Secondary rays
A
outer edges of beam and do not have enough energy to pass through the patient
part of primary beam
18
Q
Cone
A
beam limiting device that slides on the end of the tube under the filter to limit the size of the beam
19
Q
Collimator
A
beam limiting device
LEAD SHUTTER BEAM LIMITING DEVICE
adjusts down to decrease the size of the primary beam
20
Q
Advantages of limiting the beam
A
decrease the amount of radiation to the patient and you
better detail
21
Q
Backscatter
A
rays that become scattered by bouncing off object
grids are used to decrease this
22
Q
A grid is a device that either sits
A
*between patient and film
on top of cassette
built into cassette
23
Q
Grid composition
A
alternating strips of lead and spacer material
24
Q
Grid ratio
A
height of lead strips in relation to the material between
example 8:1
25
Linear grid pattern
lead strips are parallel to each other and horizontal to the surface
26
Crossed grid pattern
2 linear grids that are at right angles to each other
27
Parallel/Unfocused grid
not the most effective
| lead strips are parallel to each other and upright to the surface
28
Focused/Angled grid
lead strips in the center are parallel but the strips on the edges are angled
too effective, low quality
29
Pseudo-focused grid
combo of parallel and focused grids
prevents the absorption of primary beam at the edges
best quality
30
Inventor of the grid & year
Dr. Gustov Bucky
| 1913
31
Inventors of moving grid
1920
Hollis Potter & Dr. Bucky
"Potter-Bucky diaphragm"
32
Radiographic quality is dependent on
density
quality contrast
factors affecting detail
33
Radiographic density
the amount of black or darkness on the radiograph
34
5 main radiographic densities: most dense to least dense
```
Air
Fat
Tissues of H2O density
Bone
Enamel/Metal
```
35
4 factors affecting radiographic density
milliamperage
kilovoltage
object density
tissue thickness
36
4 ways to increase radiographic density
increase mA
increase kVp
increase developing time
increase temperature of developing
37
Radiographic contract
varying sades of gray on radiograph
| the density difference between 2 adjacent areas
38
5 things that influence contrast
```
Subject contrast
kVp
Scatter radiation
Film type
Film fog
```
39
Short scale contrast
more measurable difference between two adjacent areas on radiograph
black and white
40
Long scale contrast
less measurable difference between 2 adjacent areas on radiograph
more shades of gray
41
Radiographic Detail
sharpness and clarity of rad
42
Geometric unsharpness & causes
```
type of decrease in radiographic detail
fog (fuzziness) on a particular area of the radiograph
poor screen/film contrast
focal spot size
focal film distance
motion
```
43
Geometric distortion and magnification
type of geometric unsharpness
"flashlight effect"
elongation- object appears longer than actual size
foreshortening- object smaller than actual size
does not effect quality, only size
44
Radiographic noise
type of geometric unsharpness
| variations in density not associated with normal tissue/bone densities
45
2 types of radiographic noise
Mottle- grainy due to wrong film type, dirty chemicals in processor
Artifacts- fogged film
46
Black crescents or lines - causes
static electricity
finger prints
roller marks
47
Black areas - causes
exposure to white light
48
White areas - causes
grid lines
overlapping body parts
too much difference in body measurement
49
Film too dark
overexposed
| decrease technique
50
Film too light
underexposed
| increase technique
51
Doubly dark
can barely distinguish the object
| all black film
52
1/2 Doubly dark
able to distinguish object from the rest of primary beam but dark around the edges
not very good detail
53
1/4 Doubly dark
able to distinguish object, but just slightly dark
| cant see small details
54
Doubly light
can barely distinguish the object almost all grayish-white
55
1/2 Doubly light
able to distinguish object, but hard to recognize most detail
56
1/4 Doubly light
able to distinguish object, can see detail, but not small details
57
Doubly dark & Doubly light adjustment values
kVp- 15%
| mAs- 50%
58
1/2 Doubly dark & Doubly light adjustment values
kVp 10%
| mAs 30%
59
1/4 Doubly dark & Doubly light adjustment values
kVp by 2-3
60
Purpose of film
provide a permanent record that contains vital dx info
61
X-ray film base
transparent polyester that provides flexible support
62
X-ray film emulsion
gelatin suspension of silver halide crystals that coat the film evenly
63
Silver Halide
compound made up of silver and either bromine, chlorine, or iodine
silver bromide crystals are the most common type
64
What happens when X-rays hit the film
converts silver halide into black metallic silver
| how much is converted depends on films sensitivity
65
Film sensitivity
how sensitive the film is to the xrays
can be sensitive to either blue or green spectrum of light
more sensitive= faster speed
66
Fast speed film
larger silver halide crystals
requires less exposure from xrays
poor image detail
good for body cavities
67
Slow speed film
smaller crystals
decreased sensitivity
increased detail
68
Medium film (par)
most commonly used
| fairly good detail without too much radiation
69
Film storage and handling
store in vertical position
temp. should be kept 50-60 degrees with low humidity
film is least sensitive to red light and most sensitive to white light
70
2 types of film holders
cassettes
| cardboard (dental rads)
71
Intensifying screens
>95% of the exposure recorded is from the light coming from screens
sheets of luminescent phosphor crystals bound together and mounted in cassette
when the crystals are struck by xrays, they fluoresce and convert the xrays into visible light
72
4 parts of intensifying screen
1. Base layer/support
2. Reflective- reflects light toward film
3. PC layer- blue or green fluoresce
4. Protective coat
73
Calcium tungstate screen
Old version
invented in 1896 by Thomas Edison
emissions of blue light
doesn't convert light very well
74
Rare Earth Phosphor screen
much greater xray to light conversion
4x the ability to convert
emission fo light can be green or blue
decreases radiation dose
75
Fast screen speed
decreased exposure time
larger crystals
decreased detail
more efficient light conversion
76
Slow screen speed
Increased exposure time
smaller crystals
increased detail
less efficient light conversion
77
Medium screen speed
most common
| medium screen with medium film
78
Screen care
cleaning solution recommended by manufacturer
70% alcohol solution
Kim wipes- never ever use paper towels!!!
79
Layers of cassette
1. cassette top
2. top padding
3. intensifying screen
4. film
5. intensifying screen
6. bottom padding
7. cassette bottom
80
5 steps to processing any film
1. developing
2. rinsing/stop bath
3. fixing
4. washing
5. drying
81
Developer
alkaline chemical that converts latent image into visible image
82
Rinse bath
stops the developing process
rinses developer off the film
prevents contamination fo the fixer
83
Fixer
an acidic solution that removes the unexposed crystals and hardens the gelatin coating to prevent damaging from drying
84
Washing
removes the chemicals from the film
| in manual processing, the film should be washed for 30 min.
85
Manual developing
68 degrees for 3 min.
for each degree lower than 68 degrees increase time by 30 seconds
for each degree higher than 68, decrease time by 30 seconds
never develop for longer than 5 min or shorter than 2 min.
86
Fixing
twice the developing time
87
Clearing time
the minimum amount of time film needs to be in the fixer
| 20 seconds
88
2 types of water baths
stationary
circulating
rinse 20-30 min.
hang to dry
89
Automatic processing
involves some routine except operates at a much higher temp. and special chemicals to speed up processing (90-94 degrees)
90
Care for manual equipment
buy dilute chemicals
concentrated chemicals
needs to be kept clean and changed regularly
91
Care for automatic equipment
service tech will come service the machine every 3-4 months
92
Silver recovery
any old film must be sent to silver recovery
93
Film identification
all radiographs must contain a permanent label
94
Film ID must include
name and address of hospital
date
patient and owners name
age, sex, breed, DOB
95
3 methods of labeling
lead markers (old version)
lead impregnated tape (equine)
embosser
96
Split plates
when more than one view can be placed on a piece of film
light area must be closed only to specific area to be radiographed
cover un-used parts with lead
97
Thoracic Radiographs most common visible structures
Heart, lung fields, trachea, rings, aorta, cranial and caudal vena cava
98
D/V best for
heart evaluation
99
V/D best for
lungs
| never do V/D for dyspnic patient
100
Lateral
right side down
101
Dyspnic patient postions
standing or sternally recumbent
| lateral decubitus
102
Most common visible structures on abdominal xray
```
Liver
Stomach
Kidneys- left= lower
Urinary bladder
+/- intestines
+/- spleen
```
103
Why take abdominal radiograph?
Foreign bodies
tumors
uroliths (stones)
confirm pregnancy
104
Confirming pregnancy in dogs and cats
can be anywhere from 45-50 days of age
Zippers
Dystocia (find where fetus is)
105
Why take pelvic rads?
```
dx hip dysplasia
arthritis degree
see fractures
tell where fluxation is
legg-clave-perthes syndrome= small breed dogs: jumping destroys cartilage
```
106
common pelvic views
V/D & Lateral
107
OFA stands for
Orthopedic Foundation for Animals
108
OFA established
1966 to assist breeders in addressing hip dysplasia
109
OFA also has a database for
```
Elbow deformities
Patellar deformities
Thyroid dz.
Congenital heart dz.
DNA- VonWillebrands dz.
```
110
Objectives of OFA
to gather and distribute info
to advice, encourage, and establish control problems
to encourage and finance research
to receive funds and make grants
111
How old must an animal be to be OFA eligible
2 years
112
Top 2 breeds for hip dysplasia
Bulldogs & Pugs
113
X-rays for OFA
Only 1 needs to be sent, but take 2 and keep one for backup
| 2 pieces of film in one cassette
114
OFA Embossing card
```
dogs registered name or #
DOB
Vet case or X-ray #
Date
Dr. name or hospital name
```
115
OFA radiograph is reviewed by
3 randomly selected, board certified radiologists
| breed, age, and sex of animal are taken into consideration
116
7 categories for OFA registration
```
Passing:
Excellent hip joint conformation
Good hip joint conformation
Fair hip joint conformation
Failing:
Borderline hip conformation
Mild hip dysplasia
Moderate hip dysplasia
Severe hip dysplasia
```
117
Penn Hip official name
Pennsylvania Hip Improvement Program
118
PennHip established in ___ by ___
1983
| Dr. Gail Smith
119
PennHip asses
the quality of K9 hip joint and quantitatively measures hip joint laxity
120
PennHip is accurate in puppies as young as
16 weeks old
121
PennHip has been on the market since
1994
122
3 factors that compose PennHip
diagnostic radiographic technique
network of trained vets
medical database for scientific analysis
123
3 views required for PennHip
Extended
Compression (frog leg)
Distraction (hind legs placed in position perpendicular to the table top)
