Image production-Image Acquisition and Evaluation

Tube angulation will produce which of the following types of shape distortion?

Elongation

Which of the following conditions would be considered hard to penetrate?

Osteosclerosis

When an object is placed halfway between the tube and image receptor the image will be how many times larger?

2x

What type of distortion results from the increase in OID?

Size

Why is automatic exposure control (AEC) useful in controlling receptor exposure?

1. Receptor exposure remains constant based on patient thickness

2. AEC shuts off the beam when proper exposure is attained

3. Proper exposure reduces repeat rate

All 3

Which of the following occurs when the OID is increased?

Image is magnified

What is the main reason why beam filters are used in radiography?

Reduces patient exposure

Misrepresentation of true size or shape of an object is the definition of which of the following?

Distortion

A technique of 400 mA, 0.25 seconds, non-grid could be converted to a technique of 200 mA, with an 8:1 grid and how many seconds?

2.0

Density was the term used to describe the overall blackening of a film-screen radiograph. What term is used in digital imaging yo describe this radiographic quality?

Receptor exposure

Which of the following conditions would be considered easy to penetrate?

Degenerative arthritis

In digital imaging, each pixel represents a three-dimensional volume of tissue known as a:

Voxel

Time can be decreased by ½ if the kVp is increased by what percentage?

15%

A misrepresentation of the shape of an object may be caused by which of the following?

1. An angled object

2. An angled central ray

3. An angled image receptor

All 3

Which of the following is NOT one of the three elements that affect shape distortion?

SID

Why is contrast needed in a radiographic image?

1. Makes detail visible

2. Increases sharpness of detail

3. Decreases need for distortion

1 only

If a technique of 300 mA, 1/10 second and 60 kVp is to be changed to 69 kVp, what would be the new time?

1/20 second

Which of the following CR imaging plates should be selected to produce an image with the best spatial resolution

8×10”

Which of the following factors is the best for reducing the risk of motion?

Shortest possible exposure time

In radiography, an object that is larger than its true size is said to be:

Magnified

Changing the shape of an object is called what?

Distortion

The quality or energy of an x-ray beam is determined by which of the following?

kVp

Which of the following technique adjustments should be made when radiographing a geriatric patient with osteoporosis?

Decrease kVp

How are mA and seconds related to each other when used to maintain receptor exposure?

Inversely proportional

How should kVp be increased when radiographing a part in a fiberglass orthopedic cast?

5 kVp

When motion is a problem, time can be reduced by ½ if the kVp is increased by what percentage?

15%

Which of the following may be the cause of an overexposed image?

SID is too low

Which of the following distances (SID) would produce the least distortion?

72”

Subject contrast will be the lowest with which of the following body types?

Hypersthenic

What are the two types of distortion that can reduce the quality of a radiograph?

Size and shape

Focal spot size selection will affect which of the following?

Spatial resolution

If the SID is halved, which of the following changes must be made in order to maintain the same exposure?

mAs reduced by 4x

An underexposed radiograph may be caused by which of the following?

1. Grid cutoff

2. SID too low

3. Grid ratio too low

1 only

Which of the following will have the greatest effect on size distortion?

OID

Which of the following will have the greatest effect on reducing motion on an abdomen radiograph?

Suspend respiration

The difference between light areas and dark areas in a radiograph is a definition for which of the following?

Contrast

At which of the following source-to-image distances listed below would the anode heel effect be the most noticeable?

40 inches

Which of the following radiographic qualities determines the sharpness of detain in the finished radiographs?

Spatial resolution and distortion

The ration of SID to SOD represents which of the following?

Magnification ratio

If the central ray is perpendicular to the image receptor, but the part is angled, what will be the result?

Foreshortening

Which of the following combinations of exposure settings will result in a radiograph with the least amount of geometric blur?

50 mAs, 75 kVp, 8:1 grid ratio, 72” SID, 0.6mm FFS

Which of the following is the most important factor in controlling size distortion?

OID

The measure of the amount of detail in a digital image defines which of the following?

Spatial resolution

How will increasing the focal spot size affect the spatial resolution on a radiograph?

Decrease spatial resolution

Amorphous silicon and amorphous selenium receptors are types of:

Flat panel detectors

To avoid shape distortion, which of the following must be paid close attention to?

Part angulation

Which of the following affects shape distortion?

X-ray tube angulation

How will the use of radiographic grids affect the amount of scatter radiation reaching the IR?

Less scatter will reach the IR

The quantity of x-rays produced is dependent upon which of the following?

mAs

How much mAs will be generated if the control panel is set at 200 mA and 1/5 second?

40 mAs

What is a major benefit of a fixed kVp technique chart?

Adequate part penetration

In order to obtain the most spatial resolution the OID should be what?

As short as possible

If the kVp is increased 15%, how much must the mAs be reduced in order to maintain the same receptor exposure?

50%

How will decreasing the focal spot size affect spatial resolution?

It will decrease unsharpness

If the mA is set at 400 and the mAs obtained is 80, what is the exposure time?

0.2 seconds

A detector element (DEL) size of 200 microns will produce how much spatial resolution?

2.5 line pairs per millimeter

What are advantages of using high kVp techniques?

1. Less patient exposure

2. Longer tube life

3. All parts are well penetrated

All 3

Which of the following will occur when the tube angle is decreased?

Shape distortion will decrease

Which of the following will NOT contribute to the underexposure of an image?

Focal spot size is too large

If the exposure time is cut in half, how must the mA be adjusted to maintain receptor exposure?

Doubled

Spatial resolution can be improved by reducing which of the following?

Focal spot size

A flat-panel detector’s detector element (DEL) size determines which of the following?

Spatial resolution

Which of the following is NOT considered one of the geometric factors that control spatial resolution?

Size of the object

Which of the following occurs when the image plate or flat-panel detector is grossly overexposed?

Saturation

Which if these is the best method to reduce scatter radiation which causes fog?

Collimation

Which of the following can be used to reduce unsharpness?

1. Increase SID

2. Decrease focal spot size

3. Decrease OID

All 3

Which of the following techniques will produce the greatest image receptor exposure?

300 mA, 0.33 seconds, 80kVp

Changing the mAs controls which of the following?

Quality of the x-ray beam

How is spatial resolution measured in digital imaging?

Line pairs per millimeter

Which of the following will produce the largest image?

40” SID, 5”OID

According to the line-focus principle, the effective focal spot is always _____ the actual focal spot

Smaller than

Which of the following can be done to help compensate for an angled part?

Align the tube, part, and IR

Which of the following will affect the production of scatter radiation?

1. Irradiated field size

2. kVp used

3. Part thickness

All 3

As matrix size increases, image resolution:

Increases

What advantage is the re to magnifying an object?

1. Spatial resolution increases

2. Small objects become visible

3. There is less distortion

2 only

Which of the following may be used to control motion during a radiographic exam?

1. positioning sponges

2. Precise verbal instructions to the patient

3. Shortest possible exposure time

All 3

According to the Nyquist frequency, an analog signal should be sampled at what frequency to avoid aliasing or Moiré effect on the resulting digital image?

2x per cycle

Which of the following is a reason for the loss of spatial resolution in a radiograph?

All of the above

How will increasing the OID affect the spatial resolution on a radiograph?

Decrease spatial resolution

Which of the following would be used to minimize size distortion?

1. Shortest possible OID

2. Smallest focal spot size

3. Longest SID

1 and 3 only

If it is impossible to get the part close to the IR, what can be done to compensate?

Increase SID

What is the magnification factor if an object measures 4cm but the radiographic image is 8cm?

2x

Which of the following will occur when the OID is decreased?

The image is closer to actual size

An insufficient amount of mAs will produce a digital image with:

Quantum noise

Which of the following will keep size distortion to a minimum?

Increase SID

A 8:1 exposure requires 10 mAs. How much mAs is needed if a 16:1 grid ratio is used?

15 mAs

Spatial resolution is NOT affected by which of the following?

kVP

Which of the following radiographic procedures requires a long scale of contrast?

Chest

Which of the following effects will result from precise collimation?

1. Less biological tissue exposed

2. Less scatter radiation is produced

3. Radiographic quality is improved

All 3

Which of the following would be the most effective at absorbing scatter radiation?

12:1 grid

If the SID is increased the same as the OID, what will the resultant radiograph show?

An increase in size distortion

Which of the following types of information must be on all radiographs?

1. Patients name

2. Date of exam

3. Right or Left markers

All 3

Size distortion is affected by which of the following?

Geometric factors

The size of the pixel produced when a CR image is read depends on which of the following?

1. The speed of the imaging plate as it passes through the reader

2. The frequency with which the data is sampled

3. The dimensions of the laser beam

All 3

Which of the factors will always have an effect on spatial resolution?

OID

Insufficient exposure to the image receptor will cause which of the following artifacts?

Quantum mottle

Patient motion can be used to an advantage in which of the following projections?

Transthoracic lateral humerus

A wavy pattern results when two geometrically parallel lines are superimposed is referred to as what?

Moiré effect

A fixed kVp technique chart uses which of the following?

FIxed kVp and variable mAs

How would an image with just a few shades of gray be described?

High contrast