Principles of Exposure and Image Acquisition

The control used to adjust the contrast on the viewing monitor:

Window width

The distance from the tube target and the IR:

Source-to-image distance (SID).

What technical factor produces a high contrast image?

Low kVp

A solid piece of aluminum with steps of varying thickness is called a(n):

Penetrometer

Projects the part so that it appears longer than it really is:

Elongation

A term used to describe the situation in which a grainy or mottled image is created:

Quantum mottle

Refers to the mass density, or atomic number, of the body part:

Tissue density

Spatial resolution is primarily controlled by what five factors?

OID, SID, focal spot size, motion, and quantum mottle

Technical factor that produces a low contrast image:

High kVp

Distortion is primarily controlled by what five factors?

OID, SID, CR angle, part position, and IR position

An image that is too dark is said to be:

over-exposed

Refers to the sharpness of the image:

Spatial resolution

This term is used in place of density in the digital environment:

Brightness

The process of restricting the primary x-ray beam coming out of the tube housing:

Collimation

Is the actual anatomic area, body part, or structure shown in the radiographic image:

Umbra

Projects the part so that it appears shorter than it really is:

Foreshortening

A geometric property that refers to the differences between the actual subject and the radiographic image:

Distortion

A general, unwanted exposure to the radiographic image is called:

Fog

The prime factors of exposure:

mA, Exposure time, kVp, and SID

The four primary factors that affect how the x-ray image looks (Photographic and Geometric factors):

Density, contrast, distortion, and spatial resolution

The primary controller of radiographic density

mAs

Also called short-scale contrast:

High contrast

A photographic property defined as the difference in radiographic density between adjacent portions of an image:

Contrast

Involves movements in which the patient has no control, such as tremors, peristalsis, and heartbeats

Involuntary motion

The relationship between the SID and intensity of the beam is expressed by the:

Inverse square law

The photographic property that refers to the overall blackness or darkness of the radiographic image:

Density

Also called long-scale contrast

Low contrast

Tissue densities within the patient are called:

Subject contrast

Is the result of unequal magnification of the actual shape of the structure:

Shape distortion

The distance between the subject and the IR

Object-image distance

Movement is that is normally controllable:

Voluntary motion

Is always in the form of magnification enlargement:

Size distortion

Term that describes the “unsharp edges” of the body part:

Penumbra

The unit used to indicate the total quantity of x-rays in an exposure is:

Milliampere-seconds (mAs).

If an image were made using 500 mA, 0.1 second, and 75 kVp, what would the mAs be for this exposure?

50mAs

Two exposures are made using the following technical factors:
Image A: 500 mA, 0.05 second, 72 kVp
Image B: 200 mA, 0.125 second, 72 kVp
Which image would have the greater density?

Both would have equal density because they both produce the same mAs

Which of the following, if increased, will result in increased radiographic density

1. Increased mA

2. Increased exposure time

3. Increased kVp

All 3

If the radiographic image is overexposed, which change in exposure factors should be used to correct the problem?

Decrease mAs

The distance between the tube target and the IR is termed

Source-to-image distance (SID).

The relationship between SID and x-ray beam intensity is expressed in the __________ law.

Inverse square

The inverse square law governs the relationship between x-ray beam

intensity and distance

The inverse square law states that the intensity of the x-ray beam is _________ to the square of the distance.

Inversely proportional

What are the four primary aspects that directly affect how the x-ray image looks? (photographic and Geometric)

Density, contrast, distortion, and spatial resolution

The difference in density between any two adjacent portions of the image is called:

Radiographic contrast

The primary controlling factor of radiographic density is:

mAs

The primary controlling factor of contrast is:

Kilovoltage

When it is necessary to differentiate tissues with similar tissue densities, what image quality factors is most desirable?

High contrast

Generalized unwanted exposure on the image is called:

Fog

Fog affects radiographic quality by causing:

Decreased contrast

The unsharp, “fuzzy” appearance of margins of anatomic structures within the radiographic image is called

Penumbra

A change from the small focal spot to the large focal spot results in:

Decreased resolution

With a large OID, the reduction of excessive magnification is accomplished by:

increasing the SID

An increase in OID will result in:

Increased magnification

Motion of the patient, the tube, or the IR during the exposure results in decreased:

Resolution

If a radiographic image appears blurred, what aspect of image quality is affected?

Spatial resolution

Quantum mottle or graininess in the radiographic image because of too few photons interacting with the body part will affect image quality by decreasing the:

Spatial resolution

Which of the following minimize shape distortion?

1. Position plane of subject parallel to plane of IR

2. Position plane of subject perpendicular to plane of IR.

3. Position the CR perpendicular to IR and subject.

1 and 3 only

Which of the following will increase spatial resolution?

1. Increase in SID

2. Increase in OID

3. Decrease in focal spot size

1 and 3 only

Which quality factor is a key to visibility of detail?

Contrast

The factors that affect x-ray quality are

1. Kilovoltage.

2. Filtration.

3. mAs.

1 and 2 only

If the mA doubles, the quantity of exposure will:

Double

If the mA doubles, dose to the patient will:

Double

The primary controlling factor of penetration of x-rays is

kilovoltage peak (kVp).

If the SID doubles, the quantity of x-rays will decrease by:

4x

Tissue density refers to the __________ of the body part.

Mass density or atomic number

Contrast is directly influenced by

1. SID

2. Fog

3. Collimation

2 and 3 only

Fog is primarily caused by:

Scattered radiation

The geometric factors that affect the formation of the image are:

1. SID

2. OID

3. Focal spot

All 3

Which of the following would be considered involuntary motion by the patient?

1. Tremors

2. Peristalsis

3. Breathing

1 and 2 only

The overall darkness, or blackness, within a radiographic image is referred to as:

Density

The mass density of the radiographic subject is referred to as:

Tissue density

Unequal magnification of different portions of the same object is termed:

Distortion

Another name for size distortion is:

Magnification

The distance between the subject or part and the IR is referred to as:

Object-to-image receptor distance (OID)

The term used in the new digital imaging environment to replace density is:

Brightness

When a body part appears on a radiograph as shorter than it actually is, the term used is:

Foreshortening

When a body part appears on a radiograph as longer than it actually is, the term used is:

Elongation

The geometric factors that affect the formation of the image are

1. SID.

2. OID.

3. Focal spot.

All 3

An increase in mAs causes ________ in beam quality and ________ in beam intensity.

no change; an increase

There is a direct relationship between the quantity of x-rays and the ________.

milliamperage

If mAs is increased from 20 mAs to 40 mAs, the patient dose will _______.

doubled

Patient thickness should be measured with the _______.

caliper

Added filtration has the effect of ________ the beam quality and ________ patient dose.

increasing; reducing

When only the intensity needs to be changed, only the _______ should be adjusted.

mAs