Ch 1 System Operation And Components Flashcards Preview

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Flashcards in Ch 1 System Operation And Components Deck (126)
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1

Ct uses X-rays to image individuals at different

P 1

Cross sectional anatomy

2

Reconstructed image

Measurement of photons of xray beam in which each tissue has its own characteristic intensity

3

Overview of Ct system

Control panel
Computer
Scan controller
Digital analog converter
Gantry
High voltage
Generator
Info converted into tiny electrical signals
Pass through amplifier
Analog signal sampled
Then digitized by analog digital converter
Data stored temporarily in raw data file
Calculated image by array processor
Image transferred to host computer

4

Scan controller

Responsible for timing and operation of patient table , gantry , and high voltage generator

5

Digital analog converter (dac)

Electronic signal converted into analog or continuous waveform

6

Gantry

Contains X-ray tube and detectors

7

High voltage generator

Generates high voltage potential between cathode and anode

8

1st commercial scanner

1973

9

First gen scanner

Type beam?
What does?
Scan time?

Pencil beam
Single detector moved 180 degrees
Tube detector moved across patient then rotated 1 degree
Scan time : 5mins

10

2nd gen Ct


Type beam?
What does?
Scan time?

Fan beam
Multiple detectors in straight line
Tube detector moved across patient then rotated 5 degrees
Total scan time : 20 sec per image

11

3rd gen Ct

Type beam?
What does?
Major difference?
What does difference help with?
Scan time?

Fan beam geometry

Detector array rotates with tube in tube/detector assembly within gantry

Detector array curved arc

Arc arrangement improves reproducibility across array and minimize artifacts

Scan time: less 1 sec per image

12

Scanners today mostly based off?

3rd gen scanner

13

Scan

Collection of anatomical information during time X-ray beam is on

14

4th gen scanner

Similar to 3rd gen

Tube generates X-rays in fan beam geometry , rotates about gantry same as 3rd

Difference: detectors don't travel with tube in 4th. Circle around patient. Many more detectors

Same time: less 1 sec per image

15

Slip ring technology

Large rotating ring surrounds gantry aperture

Eliminates winding of high tension cables from high frequency generator

16

Electrical brushes

Conveys electrical power and data to components on rotating ring

17

Slip rings conveys scanning instructions from _______to gantry component in order preform scan

Conveys measure attenuation data from patient to computer and _______ in order facilitate and image

Host computer

Array processor

18

Sling ring transfers

Electrical signal
Scanning instructions
Detected signal between stationary components and rotating gantry components

19

Multi row detectors
From?
Scan time vs?
Type beam?
Aka?

Collect from multi slices

Faster scan without increase in slice thickness or varying pitch

Very thick X-ray beam and multiple detector arrays

Aka : mdct, msct, multi array scanners

Each parallel detector array composed hundreds scanners along arc

20

Single row detector

Detector array aligned in one row

21

Multi row detector scanner

Detectors/ why?

Equation

Multiple parallel detector arrays in order to vary the number of slices collected in single,rotation and to vary slice thickness

When thick X-ray beam is measured by multiple parallel detector array , thickness of beam \ total number detectors = desired slice thickness

22

Mdct beam is ____ shape?

Cone

23

___ detector scanners collect info from multiple anatomical slices in each rotation of the X-ray tube

Multirow detector scanner

24

Benefits of multi row detector scanner

Fast scans

Increased anatomical coverage

Scanner with thinner slices to improve resolution along slice direction

25

Electron beam Ct (ebct)

No X-ray tube

Very fast scan times: good for cardiac Ct and coronary artery imaging

Produce electron beam that streams from electron gun and which I electromechanical directed toward an army of tungsten anodes.

X-ray beam generated when electron beam strikes anode

26

Pet/Ct scanner

Nuclear imaging modality that involved injection of slightly radioactive pharmaceutical

Malignant tissue characterized by rapid growth and high metabolism , agent accumulation in abnormal tissue

27

Fusion imaging

Comparison of two imaging modality yielding coregistered images

28

Value in pet image resulting Ct

Associate change in metabolism with a specific structure

29

Attenuation correction

S

30

Cone beam oncology

Verifies patient positioning before radiation therapy

High quality 3D image while patient positioning in linear accelerator

Clinicians can compare images for patients treatment plan and positioning adjustment that puts tumor in direct in X-ray beam path