Spatial Resolution

Question 1

Define resolution

Answer 1

The accuracy & clarity in which anatomical lines are seen(sharpness of an image)

Question 2

What is resolution also referred to as

Answer 2

Sharpness
Detail
Definition

Question 3

What is an objective evaluation of sharpness

Answer 3

Measuring the amount of sharpness on the image

Question 4

How is spatial resolution measured

Answer 4

Line pairs / millimeter

Question 5

More line pairs = good resolution or bad resolution

Answer 5

Good resolution

Question 6

What is the test tool range

Answer 6

0.5 - 5.0 line pairs per millimeter

Question 7

What is the maximum line pairs per millimeter for Digital radiography

Answer 7

4 line pairs per millimeter

Question 8

What is the maximum line pairs per millimeter for computed radiography

Answer 8

6 line pairs per millimeter

Question 9

What are line pairs in a given length referred to as

Answer 9

Spatial frequency

Question 10

What creates one wave length?

Answer 10

One line and one space

Question 11

Define spatial frequency

Answer 11

Number of waves passing a fixed point per second

Question 12

What is spatial frequency measured in

Answer 12

Cycles per unit of length
(Ex: 6 cycles / millimeter)

Question 13

Are spatial frequency and spatial resolution the same?

Answer 13

Yes

Spatial resolution uses line pairs per millimeter

Spatial frequency uses cycles per length

Question 14

What is spatial resolution measured on

Answer 14

The sharpness of an image

Question 15

How is spatial frequency measured

Answer 15

Represent the structural complexity of anatomical organs

Question 16

What is the relationship between spatial frequency and anatomy size

Answer 16

Inverse relationship

Question 17

Define modulation transfer function ( MTF)

Answer 17

Ability for imaging system to display small objects on the image

Question 18

What is the relationship between MTF & spatial frequency

Answer 18

Inverse relationship
As spatial frequency increases, MTF decreases

( the more detail required to see anatomy, the more difficult it is to see so…the less MTF is needed)

Question 19

What are the 3 types of resolution sharpness from the chart?

Answer 19

Geometric
Digital
Motion

Question 20

Define geometric sharpness

Answer 20

Factors that relates to the primary beam itself
- focal spot size & Distance (SID)

Question 21

Define motion unsharpness

Answer 21

Due to patient or equipment motion

Question 22

Define digital sharpness

Answer 22

Factors that inherent in digital systems that affect sharpness

Question 23

In geometric sharpness, if you increase SID to hat happens to resolution and why

Answer 23

Resolution increases because as SID increases the beam diverges LESS

Question 24

In geometric sharpness, if you increase OID what happens to resolution and why?

Answer 24

Resolution decreases because as OID increases the remnant X-rays diverge more

Question 25

In geometric sharpness if you increase FSS what happens to resolution and why

Answer 25

Resolution will decrease because as FSS increases, x rays will originate from larger surface area( more divergence)

Question 26

In digital resolution , smaller pixels make for what….which make what?

Answer 26

Smaller pixels means more pixels in the image & more pixels is better spatial resolution

Question 27

In digital resolution, what is the matrix

Answer 27

Layout (grid) of the total number of pixels ( 5x5 matrix = 25 pixels)

Question 28

Define pixel pitch

Answer 28

As pixels per mm increase the distance between them decreases

Question 29

If the size of each pixel decreases how would it effect Matrix size # of pixel/ mm Pixel pitch Spatial resolution

Answer 29

Matrix size increases # of pixels /mm increase Pixel pitch will decrease Spatial resolution will increase

Question 30

How it matrix size determined

Answer 30

By detector elements

Question 31

Smaller Detector Elements produce what

Answer 31

More pixels , which makes larger matrix size, and a smaller DEL pitch for better resolution

Question 32

How will high fill factors effect spatial resolution

Answer 32

Better spatial resolution

Question 33

What’s the best way to help reduce motion

Answer 33

Lower exposure time Communication Immobilization

Question 34

What are the reasons we use immobilization

Answer 34

For pt safety Reduce repeats Personal safety

Question 35

Which factors have NO effect of spatial resolution

Answer 35

Contrast Kvp mAs Grid Tube filtration Collimation