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Advanced Imaging > Computed Tomography- Lecture One > Flashcards

Computed Tomography- Lecture One Flashcards

1
Q

What is the most significant development in radiology in the past 40 years?

A

Computed Tomography

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2
Q

Do MRI and Ultrasound use x-ray to produce image?

A

No

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3
Q

How does the x-ray tube move for computed tomography?

A

It spins around the patient

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4
Q

When does tomography trace back to?

A

1920’s

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5
Q

How does tomography “cut” the body?

A

For a specific layer or section of the body

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6
Q

What is axial tomography?

A

The images parallel to the long axis of the body

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7
Q

What is a transverse image or one perpendicular to the long axis of the body?

A

The x-ray tube moves across the image

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8
Q

How is conventional tomography and computed tomography different?

A

Conventional uses axial tomography (parallel to the long axis of the body)
Computed uses transverse image
(One perpendicular to the axis of the body)

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9
Q

Who laid down the roots of tomography in terms of mathematics? And when?

A

Radon; 1917

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10
Q

What did Godrey Hounsfield conclude from his investigational work with pattern recognition and reconstruction techniques by using computers? And when?

A

He found that when an x-ray beam passed through a body from all directions and measurements were made of all of these transmissions, information about the internal structures of the body can be obtained
1967

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11
Q

When was CT developed by Godrey Hounsfield?

A

1969

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12
Q

What was the EMI scanner used for?

A

To CT brains only

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13
Q

Who did Hounsfield share the Nobel Prize in Medicine and Physiology with?

A

Alan Cormack of Tufts University.

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14
Q

How did Cormack contribute to win the Nobel Prize?

A

He worked out the mathematical solutions to problems in CT

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15
Q

How many major design advancements has CT been through since 1970?

A

Five

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16
Q

What did each major design advancement improve?

A

Scan time and resolution or image quality

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17
Q

Scan times have been reduced from _____ to ______

A

5 minutes to 50 ms

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18
Q

What did the first scanner use?

A

a very tightly collimated pencil beam

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19
Q

How many degrees did the 1st generation CT scanner rotate?

A

180 degrees

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20
Q

How many degrees would the 1st generation CT scanner rotation per image?

A

1 degree

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21
Q

How long would it take for one image from the 1st generation CT scanner to process?

A

5 minutes

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22
Q

How many detectors did the 1st generation CT scanner have?

A

1 detector

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23
Q

How many degrees would the 2nd generation CT scanner rotate?

A

180 degrees

24
Q

Why was there more scatter radiation from the 2nd generation CT scanner?

A

It used fan beam collimation

25
Q

How many detectors did the 2nd generation CT scanner have?

A

5 to 30 detectors

26
Q

How many degrees would the 2nd generation CT scanner rotate per image?

A

10 degrees per translation & 18 per scan

27
Q

Which had a faster scan time the 1st or 2nd generation CT scanner?

A

2nd

28
Q

How much would the 3rd generation CT scanner rotate?

A

360 degrees

29
Q

What kind of beam was used in the 3rd generation CT scanner?

A

A fan shaped beam of 30-60 degrees for full coverage

30
Q

How did the 3rd generation CT scanner have constant Source to detector distance?

A

Due to curvilinear detector array

31
Q

What happens if one detector fails in a 3rd generation CT scanner?

A

A ring appears

32
Q

Will a radiologist read a scan if there is a ring artifact?

A

NO

33
Q

What is the scan time for the 3rd generation CT scanner?

A

1 sec

34
Q

What does the 3rd generation have compared to the 1st and 2nd?

A

Superior reconstruction and resolution

35
Q

Why didn’t the 4ht generation Ct scanners last long?

A

-Cost of the detectors
-Too much scatter given off

36
Q

How many detectors are used in the 4th generation CT scanner?

A

As many as 8000 detectors

37
Q

What is the scan time for the 4th generation CT scanner?

A

1 sec

38
Q

What was eliminated from the 4th generation compared to previous scanner and how?

A

The ring artifact because it uses auto-detector calibration

39
Q

What kind of beam does the 4th generation CT scanner use?

A

Fan beam; high radiation dose compared to earlier scanners

40
Q

How does the 4th generation take an image?

A

The tube rotates around the stationary ring of detectors

41
Q

What was the 5the generation specifically used for?

A

Cardiac

42
Q

What does the 5th generation allow?

A

For continuous rotation of the tube for spiral CT

43
Q

What did the Heartscan by Imatron use?

A

An electron beam instead of x-ray tube and 50ms scan times

44
Q

What does spiral CT allow for?

A

Continuous or even overlapping data acquisition

45
Q

What would happen as the tube spins in the 5th generation?

A

the table would move

46
Q

Spiral Ct was made possible by what?

A

Slipring technology

47
Q

How did the slipring change CT?

A

It allowed the tube to continuously rotate 360 degrees versus previously without it, it needed to stop after each rotation with conventional CT

48
Q

How many detectors are used in Spiral CT?

A

As many as 14,600, each 1.25mm wide

49
Q

What does the large amount of detectors in Spiral CT allow?

A

Allows multiple slices to be made with one scan and move tissue volume to be imaged

50
Q

What are benefits of Spiral CT?

A

-Less motion artifacts
-Improve lesion detection because the reconstructed image can be at arbitrary intervals
-Reduced partial volume because of overlapping reconstruction intervals
-Reduced scan time
-Advances in computer processing allows for multi-planar reconstruction and even 3D reconstruction

51
Q

What are basic CT scanner components?

A

-Gantry includes the pedestal or table, tube, collimators, detectors, and high voltage generator
-Mechanical supports
-Operators Console
-Computers

52
Q

How many steps does the formation of CT images by a CT scanner involve and what are they?

A

3 steps
1- Date Acquisition
2- Image reconstruction
3- Image Display

53
Q

What is Data acquisition?

A

Refers to the collection of x-ray transmission measurements from the patients

54
Q

What are components of data acquisition?

A

-Generator, Gantry, and patient table

55
Q

What are power ratings for the high-frequency generator?

A

Typically from 30 to 60 kilowatts

Advanced Imaging (11 decks)

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