Self-Learning Week Flashcards
What imaging technique was used to visualize the brain before the invention of CT?
- US
- MRI
- Radiography
- Fluoroscopy
Radiography
Which mathematician introduced the transformation operator that laid the foundation for tomographic reconstruction?
- Wilhelm Roentgen
- Sir Godfrey Hounsfield
- Allan Cormack
- Johann Radon
Johann Radon
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.
decubitus
Who validated Allan Cormack’s work by building the first prototype CT scanner?
- Wilhelm Roentgen
- Allan Cormack
- Johann Radon
- Sir Godfrey Hounsfield
Sir Godfrey Hounsfield
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
- Understanding scanning parameters’ effect on tumor visualization
- Accurate patient positioning
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
To ensure precise contouring of the tumor and surrounding critical structures
what are the different field CT can be applied in
forensics, clinicals, veterinary, archaeology, industrial inspections,
why was CT created
better alternative to pneumoencephalography
what is pneumoencephalography
invasive method to visualize brain structures by draining CSF & injecting air into ventricles via lumbar puncture TRO lesions, masses, tumors
why was pneumoencephalography bad for clinical use
lacked contrast, had hazy details, difficult to interpret
what mathematical concepts are used for CT
radon transform & inverse radon transform
what is radon transform
projects 3d object to 2d image using infinite series of straight line integrals
what is inverse radon transform
exact reconstruction of 3D object assuming projections from all directions are known
In CT, what does the term ‘voxel’ refer to?
A volume element in 3D space
The first generation of CT scanners used which motion for scanning?
Translate-rotate
What is the main advantage of CT over conventional radiography?
- Higher resolution
- Elimination of superimposition of structures
- Faster imaging time
- Lower radiation dose
Elimination of superimposition of structures
The second generation of CT scanners used which motion for scanning?
Translate-Rotate
The third generation of CT scanners used which motion for scanning?
Rotate-rotate
The fourth generation of CT scanners used which motion for scanning?
rotate-fixed
The fifth generation of CT scanners used which motion for scanning?
stationary-stationary
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.
- Lower pitch results in better image quality and higher radiation dose.
- Higher pitch results in lower image quality and lower radiation dose.
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.
- High-detail imaging requirements.
- Imaging small structures like the internal auditory canal.
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.
- To focus on a specific anatomical region.
- To exclude unnecessary areas from the image.
- To include more anatomical information in the image.
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.
- Low-dose lung cancer screening.
- CT angiography.
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
- 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
What is the primary factor to consider when selecting the mA setting for the CT scan of a patient with moderate body habitus?
Adjusting for the patient’s weight and body composition
What is the primary role of kVp in a CT scan?
To measure the beam intensity or ability to penetrate anatomy
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
- Using automatic tube current modulation
- Reducing mA while maintaining adequate image quality
- Setting a higher pitch value
Grainy or Noisy CT images caused by insufficient number photons are called ___
Quantum mottle
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.
- 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.
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.
everything except
- Larger detector elements improve spatial resolution.
- Spatial resolution is not affected by the field of view.
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 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.
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 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.
what is dose modulation in CT
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
what are DRLs
Benchmark for radiation protection & optimizing patient imaging
patient dose variation is due to differences in:
- CT scanner design
- diagnostic protocols
- local based choice of technical parameters
stochastic effects are
linear non-threshold dose response
deterministic effects are
directly proportional to the dose
what are early reactions
within 1 month from treatment onset
what are late reactions
after first 90 days
exposure definition
measure of ionization produced in specific mass of air by x-rays
absorbed dose definition
any risk associated with radiation is related to amt of energy absorbed & impt for radiation protection
effective dose definition
takes into account the radiation type & tissue radiosensitivity to relate to risk of exposure
SSDE
size specific dose estimate
what does SSDE account for
patient size
what does collimation reflect
efficient use of x-ray beam & z-axis geometric efficiency
what is pitch
ratio of distance table travels per 1 full rotation to total collimated x-ray beam width
what happens if patient iso-centering is off
degrades image quality & increased dose esp when using AEC
the more detector rows there are, the ___ the dose
lower; inversely proportional relationship
