Image Acquisition and Evaluation Flashcards
Geometric blur can be evaluated using all the ff devices except
a. star pattern
b. slit camera
c. penetrometer
d. pinhole camera
Penetrometer
What pixel size has a 512 x 512 matrix with a 20 cm field of view (FOV)?
0.40 mm/pixel
In electronic imaging, as digital image matrix size increases
- pixel size decreases
- resolution decreases
- pixel depth decreases
1 only
An increase in added filtration will result in
- an increase in maximum energy of the xray beam
- a decrease in xray intensity
- an increase in effective energy of the xray beam
2 and 3 only
SID affects recorded detail in which of the ff ways?
Recorded detail is directly related to SID
Grid interspace material can be made of
- carbon fiber
- aluminum
- plastic fiber
2 and 3 only
The exposure factors used for a particular nongrid xray image were 300 mA, 4 ms, and 90 kV. Another image, using an 8:1 grid, is requested. Which of the ff groups of factors is most appropriate?
400 mA, 12ms, 19kv
An increase in kilovoltage will have which of the ff effects?
- More scattered radiation will be produced.
- The exposure rate will increase.
- Radiographic contrast will increase.
10
The xray tube used in CT must be capable of
- high-speed rotation
- short pulsed exposures
- withstanding millions of heat units
all
Decreasing field size from 14x17 in to 8x10 in, with no other changes will
decrease the amount of scaterred radiation generated within the part
Which of the ff groups of exposure factors will produce the most radiographic density?
400 mA, 70ms
The component of a CR image plate (IP) that records the radiologic image is the
photostimulable phospor
An xray image of the ankle was made at 40 SID, 200 mA, 50 ms, 70 kV, 0.6 mm focal spot, and minimal OID. Which of the ff modifications would result in the greatest increase in magnification?
4-in OID
A lateral radiograph of the cervical spine was made at 40 in using 300 mA and 0.03 second exposure. If it is desired to increase the distance to 72 in, what should be the new milliampere (mA) setting, all other factors remaining constant?
300
Which of the ff statements regarding dual xray absorptiometry is (are) true?
- Radiation dose is low.
- Only low-energy photons are used.
- Photon attenuation by bone is calculated.
1 and 3 only
The luminescent light emitted by the PSP is transformed into the image seen on the CRT by the
ADC
Which of the ff is/are true when comparing film-screen imaging to CR imaging?
- CR DQE is better than film-screen DQE.
- CR has a wider exposure range than film-screen.
- CR has better spatial resolution than film-screen.
1 and 2 only
The term windowing describes the practice of
changing the image brightness and/or contrast scale
Foreshortening can be caused by
the radiographic object being placed at an angle to the IR
Acceptable method(s) of minimizing motion unsharpness is (are)
- suspended respiration
- short exposure time
- patient instruction
all
Using fixed milliampere-seconds and variable kilovoltage technical factors, each centimeter increase in patient thickness requires what adjustment in kilovoltage?
Increase 2 kV
Unopened boxes of radiographic film should be stored away from radiation
in the vertical position
If a duration of 0.05 second was selected for a particular exposure, what milliamperage would be necessary to produce 30 mAs?
600
Factors that contribute to film fog include
- the age of the film
- excessive exposure to safelight
- processor chemistry
all
Xray photon energy is inversely related to
- photon wavelength
- applied miiliamperes (mA)
- applied kilovoltage (kV)
1 only
Characteristics of DR imaging include
- solid state detector receptor plates
- a direct-capture imaging system
- immediate image display
all
Compared with a low-ratio grid, a high-ratio grid will
- allow more centering latitude
- absorb more scattered radiation
- absorb more primary radiation
2 and 3 only
Subject/object unsharpness can result from all of the ff except when
anatomic object(s) of interest is/are in the path of CR
To be suitable for use in an image intensifier’s input screen, a phosphor should have which of the following characteristics?
all
Resolution in CR increases as
- laser beam size decreases
- monitor matrix size decreases
- PSP crystal size decreases
1 and 3 only
Pathologic or abnormal conditions that would require an increase in exposure factors include all of the following except
a. atelectasis
2. pneumoperitoneum
c. Paget Disease
d. CHF
pneumoperitoneum
In radiography of a large abdomen, which of the ff is (are) effective way(s) to minimize the amount of scattered radiation reaching the imgae receptor (IR)?
- Use of close collimation
- Use of low mAs
- Use of a low-ratio grid
1 only
Which of the ff factors contribute (s) to the efficient performance of a grid?
1. Grid ratio
2, Number of lead strips per inch
3. Amount of scatter transmitted through the grid
all
All of the ff affect the exposure rate of the primary beam except
a. mA
b. kV
c. distance
d. field size
field size
Factors that determine the production of scattered radiation include
- field size
- beam restriction
- kilovoltage
all
Image contrast is a result of
- differential tissue absorption
- atomic number of tissue being traversed
- proper regulation of milliampere-seconds
1 and 2 only
A 5-in. object to be radiographed at a 44-in SID lies 6 in. from the IR. What will be the image width?
5.7 in.
In comparison with 60 kV, 80 kV will
- permit greater exposure latitude
- produce more scatter radiaiton
- produce shorter-scale contrast
1 and 2 only
The term pixel is associated with all of the ff except
a. two dimensional
b. picture element
c. measured in xy direction
d. how much of the part is included in the matrix
d
Misalignment of the tube-part-IR relationship results in
two dimentional
Causes of grid cutoff, when using focused reciprocating grids, include the ff?
- Inadequate SID
- Xray tube off-center with the long axis of the lead strips
- Angling the beam in the direction of the lead strips
1 only
Using a short (25–30 in.) SID with a large (14 × 17 in.) IR is likely to
Increase the anode heel effect
Which of the following groups of factors would produce the least
radiographic density?
(A) 400 mA, 0.010 second, 94 kV, 100-speed screens
(B) 500 mA, 0.008 second, 94 kV, 200-speed screens
(C) 200 mA, 0.040 second, 94 kV, 50-speed screens
(D) 100 mA, 0.020 second, 80 kV, 200-speed screens
100 mA, 0.020 second, 80 kV, 200-speed screens
Chemical fog may be attributed to
- excessive developer temperature
- oxidized developer
- excessive replenishment
1,2 and 3
Greater latitude is available to the radiographer in which of the following circumstances? 1. Using high-kV technical factors 2. Using a low-ratio grid 3. Using low-kV technical factors
1 and 2 only
The differences between CR and DR include
- CR uses IPs.
- CR has higher DQE and lower patient dose.
- CR images are displayed immediately
1 only
The term voxel is associated with all of the following except (A) bit depth (B) volume element (C) measured in Z direction (D) field of view
Field of view
Using a 48-in. SID, how much OID must be introduced to magnify an object
two times?
24 inch OID
A particular radiograph was produced using 12 mAs and 85 kV with a 16:1
ratio grid. The radiograph is to be repeated using an 8:1 ratio grid. What
should be the new milliampere-seconds value?
8
The main difference between direct capture and indirect capture DR is that
Direct capture/convertion has no scontillator
The direction of electron travel in the x-ray tube is
Cathode to anode
Which of the following technical changes would best serve to remedy the
effect of very dissimilar tissue densities?
(A) Use of a small focal spot
(B) Use of a high-ratio grid
(C) High-kilovoltage exposure factors
(D) High milliampere-seconds exposure factors
High-kilovoltage exposure factors
For the same FOV, spatial resolution will be improved using
A large matrix
Which of the following are methods of limiting the production of scattered
radiation?
1. Using moderate ratio grids
2. Using the prone position for abdominal examinations
3. Restricting the field size to the smallest practical size
2 and 3 only
The absorption of useful radiation by a grid is called
Grid cut off
Types of shape distortion include
- magnification
- elongation
- foreshortening
2 and 3 only
For the same FOV, as the matrix size increases
- spatial resolution increases
- image quality increases
- pixel size decreases
1,2 and 3
During CR imaging, the latent image present on the PSP is changed to a
computerized image by the
ADC
All the following are related to recorded detail except 464 (A) milliamperage (B) focal-spot size (C) SID (D) OID
Milliamperage
A satisfactory radiograph was made using a 36-in. SID, 12 mAs, and a 12:1
grid. If the examination will be repeated at a distance of 42 in. and using a
5:1 grid, what should be the new milliampere-seconds value to maintain the
original density?
6.5
Of the following groups of exposure factors, which will produce the most radiographic density?
200 mA, 60ms, 36-in SID
Which of the following groups of exposure factors will produce the shortest
scale of contrast?
(A) 200 mA, 0.08 second, 95 kV, 12:1 grid
(B) 500 mA, 0.03 second, 70 kV, 8:1 grid
(C) 300 mA, 0.05 second, 95 kV, 8:1 grid
(D) 600 mA, 1/40 seconds, 70 kV, 6:1 grid
500 mA, 0.03 second, 70 kV, 8:1 grid
Pathologic or abnormal conditions that would require a decrease in exposure
factors include all of the following except
465
(A) osteoporosis
(B) osteomalacia
(C) emphysema
(D) pneumonia
pneumonia
Which of the following is likely to contribute to the radiographic contrast present on the finished radiograph? 1. Atomic number of tissues radiographed 2. Any pathologic processes 3. Degree of muscle development
1,2 and 3
Which of the following factors influence(s) the production of scattered radiation? 1. Kilovoltage level 2. Tissue density 3. Size of field
1,2, and 3
A 15% decrease in kilovoltage accompanied by a 50% increase in
milliampere-seconds will result in a(n)
Shorter scale contrast
Which of the following factors impact(s) recorded detail?
- Focal-spot size
- Subject motion
- SOD
1,2 and 3
Which of the following is (are) tested as part of a quality assurance (QA) program? 1. Beam alignment 2. Reproducibility 3. Linearity
1,2 and 3
Focal-spot blur is greatest
Toward the cathode end of the xray tube
How are mAs and patient dose related?
Directly proportional
Image plate front material can be made of which of the following?
- Carbon fiber
- Magnesium
- Lead
1 and 2 only
Which of the following pathologic conditions would require a decrease in exposure factors? (A) Congestive heart failure (B) Pneumonia (C) Emphysema (D) Pleural effusion
Emphysema
If a radiograph exposed using a 12:1 ratio grid exhibits increased
brightness/loss of density at its lateral edges, it is probably because the
SID was too great
. Practice(s) that enable the radiographer to reduce the exposure time required for a particular image include 1. use of a higher milliamperage 2. use of a higher kilovoltage 3. use of a higher ratio grid
1 and 2 only
If 400 mA, 10 ms, and 90 kV were used for a particular exposure using threephase, 12-pulse equipment, which of the following exposure changes would
be most appropriate for use on single-phase equipment to produce a similar
image?
Use 0.2 second
Which of the following materials may be used as grid interspace material?
- Lead
- Plastic
- Aluminum
2 and 3 only
Which of the following can impact the visibility of the anode heel effect?
- SID
- IR size
- Focal spot size
1 and 2 only
An increase in the kilovoltage applied to the x-ray tube increases the
- x-ray wavelength
- exposure rate
- patient absorption
2 only
Which of the following statements about histograms is/are true?
- A histogram illustrates pixel value distribution.
- There is a default histogram for each/different body parts.
- A histogram is representative of the image grayscale.
1,2 and 3
Which of the following is the correct order of radiographic film processing? 471 (A) Developer, wash, fixer, dry (B) Fixer, wash, developer, dry (C) Developer, fixer, wash, dry (D) Fixer, developer, wash, dry
Developer, fixer, wash, dry
If the radiographer is unable to achieve a short OID because of the structure of
the body part or patient condition, which of the following adjustments can be
made to minimize magnification distortion?
A longer SID should be used
The reduction in x-ray photon intensity as the photon passes through material
is termed
Attenuation
Exposure rate will decrease with an increase in
- SID
- kilovoltage
- focal spot size
1 only
Which of the following pathologic conditions probably will require a decrease in exposure factors?
(A) Osteomyelitis
(B) Osteoporosis
(C) Osteosclerosis
(D) Osteochondritis
Osteoporosis
Diagnostic x-rays are generally associated with
High frequency, ahort wavelength
A film/screen image exhibiting insufficient density might be attributed to
- inadequate kilovoltage
- inadequate SID
- grid cutoff
1 and 3 only
If a lateral projection of the chest is being performed on an asthenic patient
and the outer photocells are selected, what is likely to be the outcome?
Decrease density