41 Questions
What is the primary function of the photocathode in a photomultiplier tube?
To produce photoelectrons
What happens when the primary electrons collide with the first dynode surface?
The electrons liberate more electrons
What is the final stage of the electron amplification process in a photomultiplier tube?
The collection of electrons at the anode
What is the purpose of a pixelated grid in a conventional gamma camera?
To form a gamma image by recording the number of detected gamma photons
Why is it important to minimize scattered gamma photons in gamma ray collimation?
To reduce image noise
What does the gamma image produced by a conventional gamma camera represent?
A true mapping of the radioactive agents in the targeted region of interest
What is the role of the focusing electrode in a photomultiplier tube?
To direct the photoelectrons towards the first dynode
What is the result of the cascade procedure in a photomultiplier tube?
The liberation of multiple electrons
What is the main drawback of the current gamma camera collimators?
Only gamma photons passing through the collimator's holes can be registered.
What is the primary function of a gamma camera collimator?
To map gamma rays emitted from the examined region onto the scintillator.
What type of material is commonly used in the high-density plate of a parallel hole collimator?
Lead
Why is the hexagonal structured hole arrangement used in parallel hole collimators?
To maximise the exposed area of the gamma camera detector.
What determines the appropriate type of collimator for gamma ray detection?
The FOV dimension, targeted areas' dimensions, and the desired level of sensitivity and spatial resolution.
What is the purpose of gamma ray collimation?
To improve the sensitivity of the gamma camera.
What is the most common type of collimator used in gamma image formation?
Parallel hole collimator
What would improve the gamma imaging outcome?
Improving the ability of the gamma camera to maximise the detection of primary gamma photons.
What is the primary concern when designing a collimator body?
Minimising scattered gamma photon penetration
What is the main difference between diverging and converging collimators?
Field of view
What type of collimator is used for scanning small targeted areas?
Converging collimator
What is the purpose of a pinhole collimator?
To satisfy the needs of nuclear medicine clinics with small organ imaging procedures
What is the typical diameter range of a pinhole collimator's aperture?
2-6 mm
What type of material is often used to make pinhole collimators?
Metals like tungsten, lead or platinum
In which applications is the pinhole collimator particularly effective?
Paediatric scans and skeletal extremities nuclear scanning
What do converging and diverging collimators have in common?
Exit plane dimensions
What is the required pinhole diameter for small targeted structures in small animal gamma imaging systems?
1-2 mm or even lower
What is the characteristic of a low-energy collimator?
Thin septa and can be used with gamma rays of up to 150 keV
What is the purpose of a high-resolution collimator?
To achieve high resolution where required
What is the characteristic of a general purpose collimator?
20000 holes each 2.5 mm diameter, a resolution of 9 mm, and sensitivity 150 cps MBq-1
What is the trade-off of a high-sensitivity collimator?
Poorer resolution
Why is higher spatial resolution required in small animal gamma imaging systems?
To image smaller targeted structures
What is the characteristic of a high-resolution collimator compared to a general purpose collimator?
More and smaller holes
What is the purpose of using a collimator with smaller holes?
To achieve higher spatial resolution
What is the purpose of using medium-energy collimators?
To accept poorer resolution for shorter exposure times
What is the limitation of conventional planar gamma imaging?
It loses depth information and reduces contrast
How many types of emission tomography are mentioned in the text?
Two
What occurs every 6° during a SPECT scan?
The camera halts for 20-30 seconds
How many views are taken from different directions in a SPECT scan?
60 views
What is the approximate total scanning time for a SPECT scan?
30 minutes
What is the consequence of using a parallel hole collimator in SPECT?
Fewer counts in each view
What is the purpose of emission tomography?
To address the limitations of conventional planar gamma imaging
What is the benefit of using SPECT over conventional static imaging?
Better depth information in images
Understanding the principles of photomultiplier tubes, including the photoelectric effect, electron amplification, and cascade procedures.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
