Data Acquisition (4)

Question 1

Inputs (2)

Answer 1

“Data Acquisition”
All the physical/technical parameters that go into creating scan data

Question 2

Processing (2)

Answer 2

“Reconstruction”
Series of events used to transform inputs to useful image information

Question 3

Outputs (3)

Answer 3

“Image Display”
Processed data that’s displayed as pixels within a matrix
Various manipulation possibilities

Question 4

X-plane

Answer 4

Extends horizontally across scanner
(Right vs Left)

Question 5

Y-axis

Answer 5

Extends vertically across scanner
(Ant vs Post)

Question 6

Z-plane

Answer 6

Extends longitudinally thru scanner
(Sup vs Inf)

Question 7

Which axis of any given voxel represents the specific slice

Answer 7

z-axis

Question 8

SFOV

Answer 8

Scan Field of View
Entire area inside scanner that’s actually being scanned

Question 9

DFOV (2)

Answer 9

Display Field of View
Just the area processed for viewing
Set by tech based on localizer image

Question 10

Iso-center

Answer 10

Exact center of scanner representing mid-point of x- / y-axes
Ideal midpoint of patient anatomy to ensure equal exposure in all directions

Question 11

Sequential Scanning

Answer 11

“Axial” scanning

Question 12

Spiral Scanning

Answer 12

“Helical” CT

Question 13

Helical Scan Benefits (2)

Answer 13

Decreased scan time: shorter breath holds, greater comfort
Better visualization of contrast before it dissipates into blood stream/is excreted

Question 14

IV contrast will fill vasculatrue of chest within _______ and be nearly gone within ________

Answer 14

30sec
60sec

Question 15

Volume scanning is only possible with detector arrays containing at least _______

Answer 15

250 rows (must be at least as large as organ being scanned)

Question 16

Major benefit of volume scanning (2)

Answer 16

Rapid Scan
Minimal Motion

Question 17

Rotation Time

Answer 17

Time required for single tube rotation (around patient)

Question 18

Acquisition Thickness (3)

Answer 18

Thickness of each detector row
Can be “functionally” combined to increase acquisition rate (decrease scan time)
Limiting factor for reconstruction thickness

Question 19

Partial Volume Averaging

Answer 19

Loss of tissue visibility when different tissue types are averaged together w/in a slice and displayed with same HU

Question 20

If pitch is < 1 there is _______ in the helix and the scanner gets _______ views resulting in a very ________ (speed) scan with very ________ resolution

Answer 20

Overlap
Extra
Slow
High

Question 21

If the pitch is > 1 there are _______ views, resulting in a _______ (speed) scan with _______ resolution

Answer 21

Missing
Faster
Lower

Question 22

Table Movement (per rotation) Formula

Answer 22

Beam Width x Pitch

Question 23

Pitch applies only to _________ scanning

Answer 23

Helical

Question 23

Pitch is a ratio describing:

Answer 23

The distance the table moves : the beam width

Question 23

Pitch Calculation:

Answer 23

Table Movement/Beam Width

Question 24

When pitch is > 1 _________ begin to appear

Answer 24

Gaps in information