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CT boards > CT Instrumentation part 1 > Flashcards

CT Instrumentation part 1 Flashcards

1
Q

Were the first Gen CT scanners able to rotate all the way around a patient?

A

No. They used cables to power the tube in the gantry and had to be reset after exposure.

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2
Q

Which CT scanner generations were known as “translate-rotate”?

A

First Gen and Second Gen. The tube first “translated” across the patient and then the gantry “rotated” to the next position.

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3
Q

Which CT scanner generation had a “pencil beam”?

A

First Gen

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4
Q

Which scanner generation was limited to only scanning heads?

A

First Gen

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5
Q

Which ct scanner generation was the first to utilize a fan beam?

A

Second Generation

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6
Q

Which ct scanner generation used “rotate-rotate” technology?

A

Third Generation - both the tube and the detector array rotated around the patient

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7
Q

Which generation of CT scanners operated under the principle of “rotate-stationary”?

A

Fourth Generation

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8
Q

What kind of scanner does “EBCT” refer to?

A

Electron Beam CT

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9
Q

Does the Electron Beam CT scanner use an x-ray tube?

A

No, it does not. And all of it’s parts are stationary

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10
Q

What kind of studies does EBCT (electron beam CT) accel at?

A

cardiac imaging and anatomy and function scans

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11
Q

Which scanner generation has a focusing and deflection coil?

A

Fifth Generation (EBCT). The electrons get focused and deflected

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12
Q

Which ct scanner generation was known as EBCT?

A

Fifth Gen

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13
Q

The scanner that generates x-rays as a result of a high=speed electron beam bombarding stationary target rings is called a ______ scanner.

A

EBCT

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14
Q

Which of the following scanner generations first introduced the concept of whole body scanning (1st, 2nd, 3rd, 4th)?

A

Second Gen

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15
Q

What “system” are the following a part of: rotating scan frame, x-ray generator and tube, colimators, beam filter, detectors and DAS, and slip rings?

A

The Imaging System

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16
Q

Do ct scanners use three phase 12-pulse or high frequency generators?

A

The first scanners used three phase 12 pulse but modern scanners use High Frequency

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17
Q

What kVp range to CT x-ray tubes operate in?

A

120-140 kVp

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18
Q

What does the “RTM” in the RTM alloy anode of the ct x-ray tube stand for?

A

Rhenium Tungsten Molybdenum

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19
Q

Do CT x-ray tubes have a shorter or longer life than diagnostic x-ray tubes and why?

A

CT tubes have a shorter life because of the tremendous amount of heat that is produced

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20
Q

Do CT tubes have large and small focal spots like diagnostic tubes?

A

Why yes, they do.

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21
Q

what unit does the following formula produce: mA x Time x kVp x GF (Generator Factor)?

A

HU or Heat units

22
Q

What is the formula to calculate Heat Units (HU)

A

mA x Time x kVp x Generator Factor (GF)

23
Q

What is the main purpose of the Filters in the CT system?

A

They ‘shape’ the beam by harening it to make it more uniform and less polyenergetic

24
Q

What material are filters usually made out of?

A

Copper and aluminum

25
Q

In single slice acquisition what mechanical device defines slice thickness?

A

The pre-patient collimators

26
Q

Does the pre-patient collimator help to reduce patient dose?

A

Yes, it does.

27
Q

What determines the slice thickness in a multislice CT?

A

The detector aperture

28
Q

What are three advantages of slip ring technology?

A

Faster Scan times, Less delay between scans, eliminates start-stop motion problems

29
Q

The purpose of filtration in CT is to: (absorb “hard” radiation, increase beam quality, produce a more heterogeneous beam, or deflect photons)

A

Increase beam quality (make it more homogeneous)

30
Q

Pre-patient commimators: (increase the energy of the beam, cause the beam to be heterogeneous, reduce patient dose, reduce scatter reaching the detector)

A

Reduce patient dose

31
Q

Post-patient collimators (increase the energy of the beam, cause the beam to be heterogeneous, reduce patient dose, reduce scatter reaching the detector)

A

Reduce scatter reaching the detector

32
Q

Which of the following affects slice thickness in single slice CT? (beam filters, beam collimators, x-ray tube, generator)

A

Beam collimators

33
Q

Development of ______ allowed CT scanners to operate using a 360 degree rotation of the x-ray tube (crystal detectors, beam collimators, fiberoptics, slip rings)

A

Slip rings

34
Q

Efficiency, Response Time, Dynamic Range, and Stability & Reproducibility are all characteristics of this “D” word.

A

Detectors

35
Q

The ratio of the largest to smallest signal that can be detected in the detector array is know as the _____ range.

A

Dynamic

36
Q

What are the two main types of CT detectors?

A

Xenon & Solid State

37
Q

What is the other “S” name for Solid State Detectors?

A

Scintillation

38
Q

What is the other name for Xenon detectors

A

Gas Ionization Detectors

39
Q

High detection efficiency and remembering the amount of radiation sensed are two advantages of what type of detector?

A

Scintillation or Solid State detectors

40
Q

More expensive, Afterglow with Sodium Iodide (NaI) [not used anymore], must be re-calibrated between patients if using PM (photomultiplier) tube [not common], and aging problems are all disadvantages of this type of detector.

A

Scintillation or Solid State Detectors

41
Q

Simple, compact, costs less, no afterglow are all advantages of this kind of detector.

A

Gas Ionization or Xenon Detectors

42
Q

What is the primary disadvantage of Gas Ionization (xenon) detectors?

A

They are less efficient than their Solid State (scintillation) detectors

43
Q

What type of detectors are used with 4th Gen CT scanners?

A

Solid State or Scintillation Detectors

44
Q

The purpose of the detector in CT is to: (Reduce patient dose, Measure the amount of scattered radiation only, Measure the x-ray transmission through the patient, Make the beam more homogeneous)

A

Measure the x-ray transmission through the patient

45
Q

Which of the following is not a property of the detector? (beam quality, efficiency, response time, stability & reproducibility)

A

Beam Quality

46
Q

Which of the following CT detectors exhibits after-glow? (xenon gas, bismuth germanate, calcium fluoride, sodium iodide)

A

Sodium Iodide

47
Q

Which of the following is not true about scintillation (Solid State) detectors? (they have a low QDE [quantum detection efficiency], they have a high efficiency percentage, they have the potential for afterglow, they can be easily replaced.)

A

They have a low QDE (they are actually very efficient)

48
Q

What is an average amount of heat units produced for an average CT scan?

A

4 - 5 million HUs

49
Q

This “B” word is the most common shape of filter used in CT.

A

Bowtie

50
Q

The photodiode in the scintillation detector converts _____ into _____.

A

light into electronic signal

CT boards (20 decks)

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