Image Production Flashcards
(179 cards)
1
Q
Radiographic receptor exposure varies INDIRECTLY with changes in distance
As the sid increases Receptor exposure WILL DECREASE
A
Distance
2
Q
This is used to calculate the CHANGE IN BEAM INTENSITY that will result when there is a change in distance
A
Inverse square law
3
Q
Is used when you are being asked to MAINTAIN A CONSTANT RECEPTOR EXPOSURE when there is a change in distance
A
Direct square law formula
4
Q
Will increase or decrease in KVP, KEEPING ALL OTHER FACTORS CONTRAST will result in DOUBLE OR HALVING of radiographic receptor exposure
Don’t touch mas
A
15% rule
5
Q
Beam attenuators
To maintain the desired amount of radiographic receptor exposure, changes in mAs are REQUIRED to compensate for the presence of a grid between the patient.
And the IR. Mas adjustment depends on the grid ratio.
This is due to the clean up effect that grids have on the remnant radiation, scatter is eliminated by interacting with the grid.
Reduces fog effect
A
Grids
6
Q
If no adjustment to technique is made, as grid ratio increases Receptor exposure will _____
A
Decrease
7
Q
If Receptor exposure is to remain constant, adjustments in mas are required to compensate for the presence of grid between the patient and the IR
Increase in mas increases or dose
A
Grid
8
Q
The slight of adjustment in mas depends on the grid ratio is called
A
Bucky factor
9
Q
Are attenuators
DECREASES SKIN EXPOSURE
As the amount of filtration in the path of the beam increased the amount of radiation available to expose the image receptor will decrease, resulting in a decrease in receptor exposure
A
Filtration
10
Q
As thickness increases, beam attenuation increases and receptor exposure ______
A
Decreases
11
Q
As atomic number of an object increases attenuation will increase gelding a _______ in reactor exposure
A
Decrease
12
Q
_______ will increase the amount of beam attenuation of the objects involved
Will decrease in receptor exposure
A
Additive diseases
13
Q
________ will decrease the amount of beam attenuation of the objects involved
Will result in a corresponding decrease in receptor exposure
A
Destructive disease
14
Q
Increasing collimation or beam restriction results in DECREASING THE FIELD SIZE
This DECREASING IR EXPOSURE
And DECREASING the amount of scatter to the IR
A
Beam restriction
15
Q
Increase in collimation, less tissue exposured, less scatter
A
Tighter collimation
16
Q
Filtration ______ ese to pts
A
DECREASES
17
Q
A
18
Q
*defined as a variation in x-ray beam intensity with an increase in beam intensity towards the cathode end of the beam and decrease in intensity towards the anode end of the beam
A
Anode heel effect
19
Q
The variations in absorbing ability of objects within the part of interest
A
Subject contrast
20
Q
Ability of the IR to respond to variations in exposure (radiation) resulting in variations in receptor exposure
A
Image receptor contrast
21
Q
The RANGE of exposure factors that will produce a radiograph of diagnostic quality
A
Exposure latitude
22
Q
The primary controlling factor of contrast
A
Kvp
23
Q
Area of image sharoness
A
Umbra
24
Q
Area of sharpness surrounding the image
Greater on cathode side
A
Blur or penumbra
25
Effects recorded detail and magnification (size distortion) by allowing an increase in divergence of the remnant beam prior to reaching the ir
Oid
26
* as oid increase, recorded detail ___
Decreases
27
Image size (b). Sid (h)
------------------- =. --------------
Object size (b). Sod (h)
Mag factor formula
28
Effects recorded detail and mag factor (size distortion)
Sid
29
As SID increases , recorded detail INCREASES, while magnification ______
Decreases
30
Sod + oid = sid
Sid - oud = sod
Sid- sod= oid
Break downs
31
As the angle of the anode decreases the effective focal spot _______
Decreases
32
This reduction in size of the focus directed towards the images after versus the size of the actual area on the surface of the anode bombarded with electrons
Line focus principal
33
Two types of distortion and classification
Size (mag)
Shape (elongation, foreshortening)
34
Changes in OID AND SID
size distortion
35
Angulation of the tube
Angulation of the part
Angulation or ir
Motion
Shape distortion
36
Anatomically programed radiography spot (arp)
Pre programmed technique
37
Variable mas chart
Pre established kvp
Similar to phototiming
Fixed KVP chart
38
Fixed mas chart
Pre established mas
Typically a 2 kv change is made for each centimeter in part thickness
Variable KVP chart
39
Wet plaster cast will require a ________ increase in kvp
8-10%
Or 100% increase in mas
40
Dry plaster cast requires _______ increase in KVP
5-7%
Or
50-60% in mas
41
Fiberglass cast usually require _______ increase in kvp
3-4% KVP
Or 25-30% mas
42
Parts measuring greater then ________ CMS require a grid
10-13
43
*Is the ability of the system to record adjacent small structures, equipment related
Spatial resolution
44
*the sharpness of the structural edges recorded in the image
Measured in lp/mm
Spatial resolution
45
Smallest area depicted in an image
Two dimensional square that contains discrete gray shades
Size- measured end to end
Pixel
46
As pixel pitch increases, spatial resolution _____
Decreases
47
Measured center to center
Pixel pitch
48
Number of pixels per millimeter
Determined by the pixel size and pixel pitch
Pixel density
49
As pixel size decreases, pixel density ______
Increases
50
Size is used with direct capture radiography (casseteless)
Uses flat panel detector
Spatial resolution is determined by the detector element size
De used detector element size
Pitch
Fill factor
Del detector element size
51
Is a raptor of pixels light sensitive area versus a pixels total area
Fill factor
52
Small del means better
Spatial resolution
53
Two dimensional array of pixels ( x and y)
Matrix
54
Total number of pixels is
Matrix size
55
Matrix size is dependent on
Filed of view and pixel density
56
The number of pixels Sampled per millimeter as the laser scans each like of the imaging plate
Sampling frequency
57
The relationship between the sampling frequency ( number of pixel/mm can by the laser, at the rate that is two times the highest frequency present) and the spatial resolution (resulting image detail and sharpness)
Nyquist frequency
58
Results from x-ray deposition of energy in a detector
Signal
59
Range of valley's over which a digital images after all, the response
greater dynamic range will yield greater contrast resolution
Dynamic range
Or
Contrast resolution
60
Results from extraneous information (interference) limits the ability to visualize objects
Noise
61
Types of noise
Quantum
Scatter
Electronic
62
Results went to a few x-rays reached the IR- underexposure, the IR photon is starved and is related to the IR photon intensity
Increased intensity results in decreased noise, and decreased intensity results in increased noise
Quantum noise
63
Ration between "signal" (or meaningful information) and "noise" (background information)
Snr
64
As noise increases it's more difficult to?
Visualize small objects
65
Noise impacts
Perceptibly of special resolution
66
Noise decreased our ability to see all ________________ on the image
Spatial and contrast resolution
67
Radiographs are required to have what 4 things on them because they are a legal document
1. Pt data - name id nunber
2. Exam data - markers
3. Exam date
4. Institutional Data - where it was done
68
69
A minimum change of _____% is necessary to yield a noticeable receptor exposure change within image
30
70
Using a grid outside the established focal range will exhibit UNIFORM CUT OFF along lateral edges of the image
Grid focus distance decentering
71
This will cause the presence of lead strings of more frequency on one side of the ir than the other
Lateral decentering grid
72
Will cause complete cutoff towards both ends of the image
Upside down grid
73
Will result in decreased recptor exposure across the entire image.
Off level grid
74
Occurs when two linear grids are placed on top of one another to make a cross hatched grid, but the lead lines are not aligned at right angles to one another.
Moire pattern
75
May also occur with digital subtraction images if there is misalignment of the pixels
Morie patterns
76
Can occur when the laser light in a cr reader runs parallel with the area of grid lines and are projected onto a pspsnplate
Morie patterns
77
Image magnification is increased by a long oid and or short sid
Size distortion - magnification
78
Affected by angulation of the tube, angulation of the part, angulation of the IR and motion
Shape distribution
79
Results of electricity discharge when the ir is exposed to open air
Static image artifacts
80
Results from improper or rough handling
Results from the cr ir being stacked too high in storage (weight causes this artifact)
Pressure artifact
81
White streak artifact is caused by
Clothing
82
Black shadow on edges is
Scatter
83
Results from using a stationary grid or importer use of reciprocating grid
Appears as parallel opaque lines
Grid lines artifact
84
A wavy artifact in digital imaging that caused when grid lines are projected onto the IR and are parallel with the scanning laser
Morie effect or aliasing
85
Is caused when there is insufficient erasure of an image and a ghost image is seen on the new image
Ghost image
86
Made of pyrex which has a very high melting point
Maintains a vacuum environment within the tube
Helps protect internal components
Glass env.
87
Most modern x-ray tubes are dual focus meaning
They have two filaments
88
Aid in maintaining a pre-determined number of electrons (electron cloud or space charge)
Negative charge
Focusing cup
89
Focusing cup aids in this, where size of the focal spot is directed towards the IR (effective focal spot) is smaller than the size of the (actual focal spot) measured on the surface of the anode
Actual is larger
Smaller angle greater spatial resolution
Line focus principal
90
Operates on the rotor that spins and the anode during radiographic exposure
Stator and windings
Induction motor
91
*Are produced ISOTROPICALLY, meaning they are produced with EQUAL intensities in all directions
X-rays
92
100 mr/hr at 1 meter
1mgy/hr at 1 meter
Tube housing protects against this
Leakage radiation
93
94
Design to reproduce a desired amount of receptor exposure and images taken on selected body parts
Regardless of changes within the pt being examined
Aec
95
Radiographs taken on a mixed population. Patients will fall with him and accept the word diagnostic range
The images will not necessarily be identical to one another
Images will vary due to changes in the subject contrast with inpatient population
Aec
96
Designed to reduce the number of repeated radiographs taken on mixed population due to over and underexposure
Places of premium Mall position and phototimer cell selection
Aec
97
Protection for the PT in event that the aec set up pt or factors affecting the beam fail to terminate exposure
Back up timer (aec)
98
The time it takes for a system to respond and said signal to terminate the exposure
Minimum response time (MRT)
99
V= I/R
V= voltage or electrical potential
I = current measured in amps
R = resistance measured in ohms
Ohms law
100
2 pulses (+/-) per cycle alternating
Sinusoidal wave (sine)
101
Kvp x mas x factor
1.0 for single phase 1/2 for full wave
1.35 for 3 phase 6 pulse
1.41 for 3 phase 12 pulse
1.61 for high frequency
Heat units
102
In parallel what is constant
In series what is contanst
Voltage
Amps
103
Located on the primary side of the low voltage circuit of the x-ray unit
Supplies the x-ray unit with primary or low voltage (220-240)
Ac supply
104
* electrical energy supplies to the x-ray unit are alternating current (ac)
Ac supply
105
Most are single throw double blade electrical switch
Connects in series
Master wall switch
106
*Strength of emf is dependent on
1. Speed
2. Strength
3. Angle
4. Number of turns *
107
*As the number of turns increase a _______ emf is induced
Greater
108
As it approaches 90° the ______ emf is produced
Greater
109
As the magnetic field increases a ______ emf is produced
Greater
110
As speed increases, a _______ emf is produced
Greater
111
1. A wire moves across a stationary magnetic field
2. A stationary wire is placed within a moving magnetic field
3. A magnetic field that varies in intensity while a stationary wire lies within the magnetic field
3 methods to induce a emf
112
Two types of induction
Self and mutual
113
Inducing a current through a secondary coil by varying the current though primary coil
Step up
Mutual induction
114
The changing magnetic field that is created by inducing an opposing volathe in a single coil of wire
Autotransformer
Self induction
115
Transformers operate on :
Electromagnetic induction
116
Transformers require _____ to operate
Alternating current
117
Transformers require ______ within the basic x-ray circuitory
Voltage
118
The principal function of the transformer is conversion of incoming low volathe (220 volts) from the external power supply into the huh volathe (kilovoltage) necessary to produce X-rays about (95% efficient)
Transformers
119
Contains two closed cores
Primary and secondary coils are wrapped around a central portion of the core
Most efficient and commonly used of the transformers
Shell core
120
Voltage is________ proportional to the turns ratio of a transformer
DIRECTLY
121
Vs. TS
----- = ------
Vp. Tp
Transformer formula for voltage
122
The magnitude of volathe change in a transformer is dependent on the
Transformers turn ratio
123
Equals the number of secondary turns divided by the number of primary turns
Turns ratio
124
Step up transformer will step up
Voltage
125
Located within the primary or low voltage circuit
Pourpose is to determine the amount of line voltage that will be sent up to the transformer
Operates on the principal of electromagnetic self induction
As a single coil of conductor lateral as both the primary and secondary sides of autotransformer
Autotransformer
126
Auto transformer determines the
Line voltage sent to step up
127
The autotransformer is a source for
Kv
128
Also known as the high voltage or high tension transformer
Separates the x-ray circuit into primary or low voltage and secondary or high volathe sections
Step up
129
Step up transformer operates on
Electromagnetic mutual induction (two wires)
130
Converts the low voltage from the secondary side of the autotransformer into high voltage or kilovoltage, required to produce x-ray radiation in the radiographic tube
Step up transformer
131
Also known as the low voltage or step down transformer
Located within the low voltage filament circur
Operates on the principle of electromagnetic mutual induction
Filament transformer
132
Filament transformer uses _______ volts
8-12
133
Located in primary or low voltage circuit between the primary side of the step up transformer
Provides a means of controlling the duration of a radiographic exposure
Exposure timer
134
The mechanical time is
No longer in use
135
Capable of exposure times in multiple of 60
Synchronous
136
**Complex, accurate up to 1 milisecond
Electronic timer
137
Establishes the highest, safest ma at the shortest exposure time
Mas timer
138
On portables
Impulse timer
139
Utilizes an ionization chamber placed between the patient and the image recptor
Aec
140
The radiographic tube is a
unidirectional (direct current) tube
141
Dive that converts altering currently into direct
Rectifiers
142
High frequency voltage ripple is __% since the volathe wave form is nearly constant
1
143
Input phosphor - converts x-rays to light.
Photocathode- light to free electron
Anode
Output phosphur - electrons from the photocathode into light
Monitor
Xlelm
144
Provides a vacuum environment for operation of the image intensifier
Contains internal contents of the image intensification tube
Glass envelope
145
Converts the incoming x-ray photons into light photons
Intensity of light produced by the input phosphur is proportional to the intensify of remnant radiation
Diameter sizes are 25,17,12 inches
Typically made of cesium iodide
Input phosphor
146
Bonded to input phosphor
Converts light photons from the input phosphur into free electrons
Operates on a principle similar to thermoinc emission
Photocathode
147
Metal plate with a hole in its middle
Allows electrons to pass though to the output phosphur
Anode
148
Located along the full length of the image intensification tube
Directs or focuses the path of electrons from the photocathode to the surface of the output phosphur screen
Does not allow the electrons to strike the anode
Contains a smaller crystal size than the input phosphor for optional resolution
Electrostatic lense
149
Converts electrons sent from the photocathode into light photons
Typically made of zinc cadmium sulfate
Output phosphor
150
4 advantages of flat panel detectors
1. Better stability
2. Lower pt dose
3. Wider dynamic range
4. No vignetting
151
**___________ of light sensitive cells within the eye
Refresh rate
152
Cone cell, concentrated at the fovea of the eye, provides high visual acuity
Bright light vision (photo topic)
153
With all other factors remaining constant, fluoroscopic imaging of thicker body parts will result in a dimmer image.
Fluoroscopic mA is directly related to the brightness of the fluoroscopic image.
Ma is adjusting to maintain this
ABC
154
This is a fluroscopic image of is a function of the input phosphur
By reducing the area of the input phosphur focused to the output phosphur screen results in this
Magnification mode
155
Magnifying a image results in :
1.
2.
3.
Increased dose
Better spatial resolution
Better contrast resolution
156
Electronic focal point will move closer to the input phosphur
Mag mode
157
Is the signal greatest source of acute radiation exposure to the PT in the diagnostic radiology environment
Flouroscopy
158
As distance from the image intensifier from the fixed radiation decreased pt. Dose will
Decrease
159
A single unit of data is defined as a
Bit (binary digit)
160
Computed handle data in groupings known as
Byte
161
1 byte = how many bits
8
162
Determines the number of gray shades available per pixel (grayscale)
Formula= 2n
Bit depth
163
Number of bit values
2 (0 or 1)
164
Greater bit depth, higher resolution and better representation
More bits
165
* equipment that uses a light weight, individually identified (usually with a bat code) cassette that contains an imaging plate, with psp as the image Receptor
Cr
166
Phosphor layer is made of
European activated barium fluorohalide
167
Layer that contains photostimulable phosphor that traps electrons during the radiographic exposure.
The phosphors are typically made of europium activated barium fluorohalide.
There is a dye located in this layer that differently absorbs the stimulating light to prevent as much spread as possible.
Phosphur or active layer
168
An electronic image of valance electron stored in high energy tape and is made by manifest exposure to a very small bean from high energy layers
Latent image
169
Causes the stored electrons to return to their balance bands with the emission of violet light, light stimulated phosphorescence
Laser
170
Employs a laser that reads the energy stored in a conductive layer, causing the light to be emitted that is amplified by a photomultiplier.
Imaging plate reader
171
Is the Easter pattern movement of the laser across the psp plate
Fast scan
172
The mechanical movement of the psp plate into the car reader
Slow scan
173
Viewed by a very sensitive photo multiplier tube, whose electronic signal is digitalized and stored for display on a cathode ray tube or hard copy laser film
Violet light
174
Cr plates are erased by
Exposing them to bright light
175
Is a stored image (invisible)
Latent
176
Image that has been processed (visible)
Manifest
177
Stored energy dissipates over time
25% over 8 hours
178
Ei exposure index has a direct relationship to the amount of
Exposure
179
S or senstiv
