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CT & MRI > Self-Learning Week > Flashcards

Self-Learning Week Flashcards

1
Q

What imaging technique was used to visualize the brain before the invention of CT?
- US
- MRI
- Radiography
- Fluoroscopy

A

Radiography

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2
Q

Which mathematician introduced the transformation operator that laid the foundation for tomographic reconstruction?
- Wilhelm Roentgen
- Sir Godfrey Hounsfield
- Allan Cormack
- Johann Radon

A

Johann Radon

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3
Q

After the injection of air in pneumoencephalography, the patient was rotated, somersaulted, or placed in a
_____ position to depict the entire ventricular system and subarachnoid spaces.

A

decubitus

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4
Q

Who validated Allan Cormack’s work by building the first prototype CT scanner?
- Wilhelm Roentgen
- Allan Cormack
- Johann Radon
- Sir Godfrey Hounsfield

A

Sir Godfrey Hounsfield

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5
Q

When using CT imaging for treatment planning in radiation therapy, which factors are essential to ensure effective and accurate therapy?
- Understanding scanning parameters’ effect on tumor visualization
- Reducing scan time to minimize patient discomfort
- Ensuring low-dose imaging regardless of the treatment area
- Accurate patient positioning

A
  • Understanding scanning parameters’ effect on tumor visualization
  • Accurate patient positioning
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6
Q

In radiation therapy, why is CT imaging essential for planning treatment for a patient with a head and neck tumor?
- To reduce the overall treatment time
- To monitor changes in metabolic activity
- To ensure precise contouring of the tumor and surrounding critical structures
- To eliminate the need for immobilization devices

A

To ensure precise contouring of the tumor and surrounding critical structures

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7
Q

what are the different field CT can be applied in

A

forensics, clinicals, veterinary, archaeology, industrial inspections,

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8
Q

why was CT created

A

better alternative to pneumoencephalography

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9
Q

what is pneumoencephalography

A

invasive method to visualize brain structures by draining CSF & injecting air into ventricles via lumbar puncture TRO lesions, masses, tumors

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10
Q

why was pneumoencephalography bad for clinical use

A

lacked contrast, had hazy details, difficult to interpret

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11
Q

what mathematical concepts are used for CT

A

radon transform & inverse radon transform

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12
Q

what is radon transform

A

projects 3d object to 2d image using infinite series of straight line integrals

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13
Q

what is inverse radon transform

A

exact reconstruction of 3D object assuming projections from all directions are known

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14
Q

In CT, what does the term ‘voxel’ refer to?

A

A volume element in 3D space

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15
Q

The first generation of CT scanners used which motion for scanning?

A

Translate-rotate

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16
Q

What is the main advantage of CT over conventional radiography?
- Higher resolution
- Elimination of superimposition of structures
- Faster imaging time
- Lower radiation dose

A

Elimination of superimposition of structures

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17
Q

The second generation of CT scanners used which motion for scanning?

A

Translate-Rotate

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18
Q

The third generation of CT scanners used which motion for scanning?

A

Rotate-rotate

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19
Q

The fourth generation of CT scanners used which motion for scanning?

A

rotate-fixed

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20
Q

The fifth generation of CT scanners used which motion for scanning?

A

stationary-stationary

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21
Q

How does manipulating the pitch in CT scanning affect the quality of the images and the radiation dose to the patient?
- Lower pitch results in better image quality and higher radiation dose.
- Higher pitch results in better image quality and higher radiation dose.
- Higher pitch results in lower image quality and lower radiation dose.
- Lower pitch results in lower image quality and lower radiation dose.

A
  • Lower pitch results in better image quality and higher radiation dose.
  • Higher pitch results in lower image quality and lower radiation dose.
22
Q

Which of the following scenarios would benefit from using a pitch value of less than 1?
- Low-dose lung cancer screening.
- Rapid whole-body scans.
- High-detail imaging requirements.
- Imaging small structures like the internal auditory canal.

A
  • High-detail imaging requirements.
  • Imaging small structures like the internal auditory canal.
23
Q

What are the possible reasons for adjusting the display field of view (DFOV) post-acquisition?
- To focus on a specific anatomical region.
- To exclude unnecessary areas from the image.
- To include more anatomical information in the image.
- To reduce the radiation dose.

A
  • To focus on a specific anatomical region.
  • To exclude unnecessary areas from the image.
  • To include more anatomical information in the image.
24
Q

In which clinical situations would a high pitch value be preferred?
- Imaging of small detailed structures.
- Imaging of the internal auditory canal.
- Low-dose lung cancer screening.
- CT angiography.

A
  • Low-dose lung cancer screening.
  • CT angiography.
25
Q

What is the significance of scan field of view (SFOV) in CT imaging?
- It can be adjusted after the scan to display a different area.
- It limits the maximum possible display field of view (DFOV).
- It determines the total area from which data is acquired.
- It affects the initial data acquisition during scanning

A
  • It limits the maximum possible display field of view (DFOV).
  • It determines the total area from which data is acquired.
  • It affects the initial data acquisition during scanning
26
Q

What is the primary factor to consider when selecting the mA setting for the CT scan of a patient with moderate body habitus?

A

Adjusting for the patient’s weight and body composition

27
Q

What is the primary role of kVp in a CT scan?

A

To measure the beam intensity or ability to penetrate anatomy

28
Q

How can technologists optimize CT scan parameters to reduce radiation dose?
- Using automatic tube current modulation
- Reducing mA while maintaining adequate image quality
- Setting a higher pitch value
- Increasing kVp for pediatric patients

A
  • Using automatic tube current modulation
  • Reducing mA while maintaining adequate image quality
  • Setting a higher pitch value
29
Q

Grainy or Noisy CT images caused by insufficient number photons are called ___

A

Quantum mottle

30
Q

Which of the following statements about noise in CT imaging are TRUE?
- Noise is primarily composed of quantum noise due to an insufficient amount of signal (photon)
- Noise is always caused by factors that are within our control.
- Noise is seen in an image as a grainy, mottled appearance.
- Quantum noise is unrelated to the number of photons hitting the detector.
- Increasing the signal-to-noise ratio will increase the noise in the image.
- A high signal-to-noise ratio means a higher amount of true signal and lower noise.

A
  • Noise is primarily composed of quantum noise due to an insufficient amount of signal (photon)
  • Noise is seen in an image as a grainy, mottled appearance.
  • A high signal-to-noise ratio means a higher amount of true signal and lower noise.
31
Q

Which of the following statements about spatial resolution in CT imaging are correct?
- Using a kernel or filter designed for high spatial resolution can improve image sharpness.
- High spatial resolution images have well-defined edges and sharp details.
- Larger detector elements improve spatial resolution.
- Using a kernel or filter designed for high spatial resolution can improve image sharpness.
- Spatial resolution refers to the ability to differentiate between two objects of different density that are close in physical space.
- Spatial resolution is not affected by the field of view.
- Decreasing slice thickness improves spatial resolution but may increase noise.

A

everything except
- Larger detector elements improve spatial resolution.
- Spatial resolution is not affected by the field of view.

32
Q

Which of the following scenarios highlight the importance of temporal resolution in CT imaging?
- A trauma surgeon requests a rapid CT scan for a patient with multiple injuries.
- An emergency physician uses a CT scan with high temporal resolution to quickly diagnose a pulmonary embolism.
- Radiographer performs a cardiac CT to capture images between heartbeats.
- A pediatrician uses a CT scan with high temporal resolution to minimize motion artifacts in a restless child.
- A radiologist orders a CT scan with long acquisition time to capture fine details of a bone fracture.

A
  • A trauma surgeon requests a rapid CT scan for a patient with multiple injuries.
  • An emergency physician uses a CT scan with high temporal resolution to quickly diagnose a pulmonary embolism.
  • Radiographer performs a cardiac CT to capture images between heartbeats.
  • A pediatrician uses a CT scan with high temporal resolution to minimize motion artifacts in a restless child.
33
Q

Which of the following scenarios correctly illustrate the balance between image quality and radiation dose in CT imaging?
- A radiographer adjusts the mA settings to find a balance between noise reduction and radiation dose in a chest CT.
- A pediatric CT scan uses optimized dose settings to minimize exposure while maintaining diagnostic image quality.
- A trauma patient undergoes a high-dose CT scan to ensure the highest possible image quality.
- A low-dose CT scan of the abdomen provides high spatial resolution with minimal noise.
- Radiographer uses a standard dose protocol for all patients to ensure consistent image quality.
- An emergency room physician requests a low-dose head CT scan to reduce radiation exposure while still identifying a brain hemorrhage.

A
  • A radiographer adjusts the mA settings to find a balance between noise reduction and radiation dose in a chest CT.
  • A pediatric CT scan uses optimized dose settings to minimize exposure while maintaining diagnostic image quality.
34
Q

what is dose modulation in CT

A

adjusts x-ray tube current during scan to optimize image quality while minimizing patient dose

constant image quality while optimizing radiation dose regardless of patient size

35
Q

what are DRLs

A

Benchmark for radiation protection & optimizing patient imaging

36
Q

patient dose variation is due to differences in:

A
  1. CT scanner design
  2. diagnostic protocols
  3. local based choice of technical parameters
37
Q

stochastic effects are

A

linear non-threshold dose response

38
Q

deterministic effects are

A

directly proportional to the dose

39
Q

what are early reactions

A

within 1 month from treatment onset

40
Q

what are late reactions

A

after first 90 days

41
Q

exposure definition

A

measure of ionization produced in specific mass of air by x-rays

42
Q

absorbed dose definition

A

any risk associated with radiation is related to amt of energy absorbed & impt for radiation protection

43
Q

effective dose definition

A

takes into account the radiation type & tissue radiosensitivity to relate to risk of exposure

44
Q

SSDE

A

size specific dose estimate

45
Q

what does SSDE account for

A

patient size

46
Q

what does collimation reflect

A

efficient use of x-ray beam & z-axis geometric efficiency

47
Q

what is pitch

A

ratio of distance table travels per 1 full rotation to total collimated x-ray beam width

48
Q

what happens if patient iso-centering is off

A

degrades image quality & increased dose esp when using AEC

48
Q

the more detector rows there are, the ___ the dose

A

lower; inversely proportional relationship

49
Q
A

CT & MRI (12 decks)

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