Ch.2 Ct Image Formation Flashcards Preview

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Flashcards in Ch.2 Ct Image Formation Deck (83)
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1

Digital images are?

P 4

Numerical representations of an object that can be recognized and processed by a computer

2

First step generating digital image of an object?

P 4

Divide the object into a grid of small regions

3

Pixel

Picture element that's each small region of a grid

4

Rows and columns allows us to ?

P 4

Associate the location of specific structure within the object being imaged with specific pixel or group of pixels

5

Matrix

P 4

Grid of pixels

6

2nd step generating image

Sample the object in order to differentiate structures within the object and assign various shades of gray to the pixels representing the structure

7

X-ray photons that pass thru the body are measure by ______and converted into ______?

P 6

Detectors

Electric signals

8

Integer

P 6

Posit e or negative whole numbe

9

Value of integer determined by?

P 6

Signals strength

10

Display hardware

Assigns specific gray level to region of Ct image from which attenuation information was detected

11

Projection

View of anatomical cross section from particular vantage point

12

Ct scanning methods
P 8

Localizer
Conventional
Helical

13

Localizer scan
P 9

Obtained with stationary X-ray tube and patient table in motion

14

Why localizer scan ?
P 9

Aligns cross sectional slices with specific anatomical structures

15

Views used with localizer?

Ap
Lateral
Oblique

16

Length of anatomical coverage with localizer depends on?
P 9

Speed of table
Amount time X-ray is on

17

Ct localizer scan the anatomical structure appears? P 10

Superimposed

18

Ap localizer image used? P 10

Planning to specify perfectly transverse slices

19

Lateral localizer is used? P 10

Intend to angle gantry to specific oblique slices

20

Which ct yields the best quality image free of helical artifacts?

P12

Conventional ct

21

Conventional ct used today?

12

Neurological studies involving temporal bones

Obese patients

Cardiac calcium scoring

22

Conventional ct the tube rotates around the patient while the table?

Stationary

23

Raw data
P 13

Data measured at each projection placed in computer file

24

Single row detector

P 13

25

When performing a conventional scan , raw data from ____ cross sectional slice location is collected during a single rotation of the gantry?
P 13

One

26

Multi row detectors

P14

27

When performing a conventional scan of multi row detector scanner , the raw data is from ______ cross sectional slice locations collected during a single rotation of the gantry

Several

28

Raw data sample formula

Rows of detectors x # of detectors X projections required

29

Helical scan
P 16

X-rays beam spiral or corkscrew paths around patients body as the table advances through the gantry

30

Most commonly used ct today?

Helical scan