Imaging acquisition unit 3 and 4

If the radiographer is unable to achieve a short object-image distance due to structure of the body part or patient condition, which one of the following adjustments may be made to minimize magnification?

longer source-image distance should be used

What is the single most important factor controlling size distortion?

OID

Spatial resolution is directly related to:

SID

Types of shape distortion include:

1. foreshortening

2. magnification

3. elongation

1 and 3

Which one of the following sets of factors will produce the most magnification?

40 inch SID and a 4 inch OID

The line-focus principle expresses the relationship between:

the actual focal and effective focal spot

To get a magnification factor of 2, where should the object be placed?

halfway between the image receptor and x-ray tube

The effective focal spot is always larger than the actual focal spot.

false

If the SID is 40 inches and the OID is 6 inches, what is the magnification factor?

1.17

If an examination of the skull is to be taken using 400 mA, 1/8 second, 80 kVp, 36 inche SID, 4 inch OID, and if the object size is 8 inches, what will the image size be?

9 inches

As focal spot size increases, distortion would:

focal spot does not affect magnification

An object is radiographed utilizing a 40 inch SID and a 4 inch OID. What would be the resultant effect if the object is radiographed utilizing a 48 inch SID and an 8 inch OID?

increased magnification

Focal spots are represented in millimeters. Example 0.6, 0.9, 1.0, 1.2. Which focal do these numbers represent?

effective focal spot

An object is radiographed utilizing a 40 inch SID and a 4 inch OID. What would be the resultant effect if the object is radiographed utilizing a 44 inch SID and a 2 inch OID?

increased spatial resolution

Which of the following could be utilized to reduce geometric blur resulting from theuse of a large focal spot?

1. increase kVP

2. Increase OID

3. Increase SID

3 only

Use of a perpendicular beam technique should be used whenever possible:

1. decrease long scae contrast

2. minimize elongation

3. minimize shape distortion

2 and 3

A PA projection of the chest was produced with an SID of 72 inches and an OID of 8 inches. What is the MF?

1.12

On a PA chest image taken with an SID of 72 inches and an OID of 6 inches, the size of a round lesion in the left lung measures 2.6 inches in diameter on the radiographic image. What is the object size of this lesion?

2.38

When a focal spot is evaluated, the measurment for size (0.3, 0.6, 1.2 mm); which focal spot is actually being measured?

effective focal spot

Which one of the following would produce the best recorded detail?

72 inch SID, 4 inch OID, small focal spot

What does a line pair mean?

one black line and one white line

The area on the anode where the electrons hit is called the:

actual focal spot

The higher the spatial resolution, the better the recorded detail.

true

A radiograph is performed using 50 mAs, 80 kVp, 40 inch SID, and 16 inch OID and a 2 mm focal spot. The magnification factor for this image is approximately:

1.6

An object measuring 18 cm in length is radiographed at a 100 cm SID and a 10 cm OID. How long will the resulting radiographic image be?

20 cm

A condition caused by angling the xray tube against the main axis of the part is:

foreshortening

Of the following, which one of the following is MOST responsible for radiographic spatial resolution?

focal-spot size

An undistorted radiographic image will result when the object plane and the image receptor plane are:

parallel