Instrument/computer Stuff GW

Question 1

1 word = ____ bytes

Answer 1

2

Question 2

1 byte = ___ bits

Answer 2

8

Question 3

1 word = ____ bits

Answer 3

16

Question 4

Word mode max number of pixels

Answer 4

2^16

Question 5

Byte mode max number of pixels

Answer 5

2^8

Question 6

Increasing distance to detector with diverging collimator

Answer 6

Decreases magnification

Question 7

Increasing distance to detector with converging collimator

Answer 7

Increases magnification

Question 8

Increasing distance to thyroid with pinhole collimator

Answer 8

Decreases magnification

Question 9

Decreasing distance to thyroid with collimator

Answer 9

Increases magnification

Question 10

Frame mode or list mode more common

Answer 10

Frame mode

Question 11

List mode

Answer 11

Counts are stored sequentially as x and y coordinates

Question 12

Length of time each image is acquired

Answer 12

Framing rate

Question 13

Frame mode

Answer 13

All counts are collected into one storage matrix in a given time period

Question 14

Acquiring in zoom mode _______ resolution

Answer 14

Increases

Question 15

applying zoom factor post acquisition _______ resolution

Answer 15

Decreases

Question 16

What do you have to do if zoom mode is used during SPECT

Answer 16

You have to acquire a uniformity correction flood at the same zoom mode and apply it to match the pixel size

Question 17

Information density = what?

Directly affects what?

Answer 17

= the number of counts per square cm

Directly affects resolution

Question 18

What increases target to background ratio

Answer 18

Subtracting background

Question 19

What decreases signal to noise ratio

Answer 19

Acquiring more counts

Question 20

Normalization

Answer 20

Used when comparing two images with different max counts

Doubles the lower count image to better compare the two

Question 21

Correction factor for normalization

Answer 21

number of pixels in larger ROI (organ) / number of pixels in smaller ROI (background)

Question 22

If critical frequency is set too high

Answer 22

Grainy/pixelated picture

Question 23

If critical frequency is too low

Answer 23

Study is over filtered, too smoothed

Question 24

High the power factor

Answer 24

Steeper the slope
More high frequencies removed

Question 25

The lower the power factor

Answer 25

The more high frequencies are preserved

Question 26

Butterworth uses

Answer 26

Cutoff frequency and power factor

Question 27

Hanning filter uses

Answer 27

Cutoff frequency - the frequency at which the filter reaches 0

Question 28

Lower the cutoff

Answer 28

Smoother the image

Question 29

Drawback of FBP

Answer 29

Assumes no attenuation
-No attenuation correction