Self-Learning Week

Question 1

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

Answer 1

Radiography

Question 2

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

Answer 2

Johann Radon

Question 3

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.

Answer 3

decubitus

Question 4

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

Answer 4

Sir Godfrey Hounsfield

Question 5

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

Answer 5

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

Question 6

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

Answer 6

To ensure precise contouring of the tumor and surrounding critical structures

Question 7

what are the different field CT can be applied in

Answer 7

forensics, clinicals, veterinary, archaeology, industrial inspections,

Question 8

why was CT created

Answer 8

better alternative to pneumoencephalography

Question 9

what is pneumoencephalography

Answer 9

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

Question 10

why was pneumoencephalography bad for clinical use

Answer 10

lacked contrast, had hazy details, difficult to interpret

Question 11

what mathematical concepts are used for CT

Answer 11

radon transform & inverse radon transform

Question 12

what is radon transform

Answer 12

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

Question 13

what is inverse radon transform

Answer 13

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

Question 14

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

Answer 14

A volume element in 3D space

Question 15

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

Answer 15

Translate-rotate

Question 16

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

Answer 16

Elimination of superimposition of structures

Question 17

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

Answer 17

Translate-Rotate

Question 18

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

Answer 18

Rotate-rotate

Question 19

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

Answer 19

rotate-fixed

Question 20

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

Answer 20

stationary-stationary

Question 21

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.

Answer 21

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

Question 22

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.

Answer 22

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

Question 23

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.

Answer 23

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

Question 24

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.

Answer 24

• Low-dose lung cancer screening.
• CT angiography.

Question 25

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

Answer 25

- 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

Question 26

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

Answer 26

Adjusting for the patient's weight and body composition

Question 27

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

Answer 27

To measure the beam intensity or ability to penetrate anatomy

Question 28

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

Answer 28

- Using automatic tube current modulation - Reducing mA while maintaining adequate image quality - Setting a higher pitch value

Question 29

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

Answer 29

Quantum mottle

Question 30

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.

Answer 30

- 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.

Question 31

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.

Answer 31

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

Question 32

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.

Answer 32

- 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.

Question 33

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.

Answer 33

- 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.

Question 34

what is dose modulation in CT

Answer 34

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

Question 35

what are DRLs

Answer 35

Benchmark for radiation protection & optimizing patient imaging

Question 36

patient dose variation is due to differences in:

Answer 36

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

Question 37

stochastic effects are

Answer 37

linear non-threshold dose response

Question 38

deterministic effects are

Answer 38

directly proportional to the dose

Question 39

what are early reactions

Answer 39

within 1 month from treatment onset

Question 40

what are late reactions

Answer 40

after first 90 days

Question 41

exposure definition

Answer 41

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

Question 42

absorbed dose definition

Answer 42

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

Question 43

effective dose definition

Answer 43

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

Question 44

SSDE

Answer 44

size specific dose estimate

Question 45

what does SSDE account for

Answer 45

patient size

Question 46

what does collimation reflect

Answer 46

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

Question 47

what is pitch

Answer 47

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

Question 48

what happens if patient iso-centering is off

Answer 48

degrades image quality & increased dose esp when using AEC

Question 48

the more detector rows there are, the ___ the dose

Answer 48

lower; inversely proportional relationship