Spatial Resolution

Question 1

What is spatial resolution?

Answer 1

The sharpness of the structural edges recorded in an image

Question 2

What does spatial resolution allow you to distinguish?

Answer 2

Two objects that are in close proximity to each other

Question 3

How is spatial resolution lost in an image?

Answer 3

Through blur distoring the edges of the image and making them run into each other and through a loss of contrast

Question 4

What is the technical name for blur?

Answer 4

Penumbra

Question 5

What is unsharpness controlled by?

Answer 5

SOD, OID and focal spot size

Question 6

How can the amount of penumbra be calculated?

Answer 6

Using the unsharpness penumbra formula

Question 7

What is the unsharpness formula?

Answer 7

Penumbra = FS x OID/SOD

Question 8

If a focal spot is 1.5 mm, OID is 30 cm and SOD is 60 cm what is the spread of penumbra?

Answer 8

Penumbra = 1.5 x 30/ 60 = 45/60 = 0.75

Question 9

How can sharpness be measured?

Answer 9

By taking the ratio of SOD/OID

Question 10

How is the relative sharpness measured between two exposures?

Answer 10

SOD/OID of exposure B divided by SOD/OID of exposure A

Question 11

What physical device can be used to measeure sharpness?

Answer 11

Line pair tool

Question 12

What factors affect the sharpness of an image?

Answer 12

Motion, geometry, focal spot size, size of detector elements, size of pixels

Question 13

How does motion affect spatial resolution?

Answer 13

Less motion produces higher spatial resolution

Question 14

How does SID affect spatial resolution?

Answer 14

Lower SID produces more magnification and less spatial resolution

Question 15

How does focal spot size affect spatial resolution?

Answer 15

Smaller focal spot size increases spatial resolution