RADS 2010 intro ws 2

True or False?

Brightness and density are interchangeable terms

False

1 multiple choice option

The term ___________ ___________ describes the concept of contrast as it is displayed on a soft-copy monitor for digital images.

Dynamic Range

Describes digital post-processing that produces changes in brightness.

Window level

1 multiple choice option

Accurately describes the digital processing that produces changes in the range of brightness.

Window width

1 multiple choice option

Regarding radiograph 27, is it penetrated?

Penetrated

1 multiple choice option

Regarding radiograph 28, is it penetrated?

Not penetrated

1 multiple choice option

Is radiograph 29 acceptable, underexposed (inadequate mAs), or under-penetrated (inadequate kVp)?

Underexposed

2 multiple choice options

Is radiograph 30 acceptable, underexposed (inadequate mAs), or under-penetrated (inadequate kVp)?

acceptable

2 multiple choice options

Is radiograph 31 acceptable, underexposed (inadequate mAs), or under-penetrated (inadequate kVp)?

underpenetrated

2 multiple choice options

High spatial resolution represents a high-frequency signal that is capable of imaging?

Smaller objects

1 multiple choice option

When differences between adjacent densities are minimal, with more discernable shades of gray.

Low/Long contrast

When the differences between adjacent densities are great, with fewer discernable shades of gray.

High/Short contrast

The 4 factors that directly affect x-ray quantity are:

Distance, kVp, mAs, Filtration

Which influencing factors affect density/IR exposure:

1. mAs

2. kVp

3. Radiolucent contrast media

4. Film/screen combination

5. Anode heel affect

6. Focal spot size

7. Filtration

8. Grid ratio

9. Beam restriction/collimation

2, 3, 4, 5, 7, 8, 9

3 multiple choice options

Occurs when the tube or the image receptor (IR) is improperly aligned and with changes in the tube angle.

Elongation

1 multiple choice option

With digital imaging systems, the primary determinant of the scale of contrast is the post-processing ______________ and ________________ sequence that sets the range of information that will be supplied to the monitor, where it will be displayed in the range of brightness.

histogram, look-up table

3 multiple choice options

___________ distortion is the misrepresentation by unequal magnification of the actual shape and can be described as either ___________ or ____________.

Shape, Foreshortened, Elongation

2 multiple choice options

Which terms are used to describe high contrast?

1. Low kVp

2. Large (wide) dynamic

3. High kVp

4. Increased contrast

5. Many shades of gray

1, 4

3 multiple choice options

X-ray quantity is a measure of the number of x-ray photons in the useful beam. It is also called: ___________ , ______________ or ________________ .

Output, intensity, exposure

SID alters the intensity of the beam reaching the IR, according to the inverse square law. To maintain IR exposure, mAs must be changed to compensate for changes in SID. What formula is used for this purpose?

Exposure maintenance

1 multiple choice option

True or False

An air-gap technique, which increases OID has an effect on contrast by increasing it.

True

1 multiple choice option

If the SID is 40” and the OID is 2”, what is the magnification factor?

1.05

A radiograph of the pelvis is produced using 25 mAs @ 70 kVp. What kVp would be needed to double the exposure?

80.5 (15% rule)

Distortion is a misrepresentation of the __________ or ____________ of the structures being examined.

Size, shape

Digital imaging recorded detail (which is primarily determined by matrix size, pixel size & grayscale bit depth) is more commonly called?

Spatial resolution

The major factor affecting the recorded detail of a digital imaging system (indirect or direct) is the size of the ____________ ______________.

Detector element

Recorded detail is also referred to as:

Spatial resolution, definition sharpness, definition

Subject contrast is the range of differences in the intensity of the x-ray beam after it has been attenuated by the subject. It is dependent on what 3 things?

Part thickness, kVp, Type/amount

The 3 factors that control recorded detail are:

Geometry (focal spot, distance and OID & SID), IR, Motion

Penumbra (unsharpness) can be calculated by using which formula?

P = Focal Spot Size x OID

SOD

3 multiple choice options

This term refers to a lack of sufficient incoming data (x-ray photons) for processing resulting in a blotchy or mottled image.

Quantum noise

3 multiple choice options

The ______________ is a major controller of image resolution because it controls penumbra.

Focal spot size

3 multiple choice options

Which factors affect distortion?

1. SID

2. OID

3. Patient thickness

4. CR alignment

5. CR angle

6. FSS

7. Motion

1, 2, 3, 4, 5

3 multiple choice options

Magnification is the only possible size distortion in radiography. Name the 2 factors that affect size distortion.

OID, SID

An image that demonstrates slight or minimal differences between densities but has a maximal total number of densities.

Decreased contrast

1 multiple choice option

Which of the factors decrease recorded detail?

1. Motion

2. Increasing focal spot size

3. Decreasing OID

4. Decreasing patient thickness

5. Increasing SID

1, 2

3 multiple choice options

Occurs only when the part is improperly aligned.

Foreshortening

2 multiple choice options

Which of the terms are used to describe high contrast?

1. Long scale of contrast

2. Few shades of gray

3. Large (wide) dynamic

4. Increased contrast

5. Many shades of gray

6. Decreased contrast

7. Short (narrow) dynamic

8. High kVp

9. Short scale of contrast

10. Low kVp

2, 4, 7, 9, 10

3 multiple choice options