83 Questions
What is a major limitation of the gamma camera?
The absorption of gamma photons by the collimator's material
What is the primary function of a collimator in gamma ray detection?
To filter out unwanted gamma photons
What is the benefit of using a hexagonal structured hole arrangement in parallel hole collimators?
It maximises the exposed area of the gamma camera detector
What determines the appropriate type of collimator for gamma ray detection?
The desired level of sensitivity and spatial resolution
What is the purpose of the scintillator in gamma imaging?
To map gamma rays onto the image
What is a characteristic of parallel hole collimators?
They have a hexagonal structured hole arrangement
What is a common material used in the construction of parallel hole collimators?
Lead
What is the purpose of doping NaI crystals with thallium atoms?
To improve the scintillator's response to gamma photons
What is the result of the interaction between the incident photons and the scintillator's material?
The release of energetic electrons
What is the fate of the electrons in an excited state?
They return to their stable state by releasing energy as optical photons
What is the relationship between crystal thickness and gamma photon absorption?
Thicker crystals absorb most incident gamma photons
What is a drawback of using thick crystals in scintillators?
Reduced spatial resolution
What is the primary factor influencing the scintillation process?
The crystal design
What is the ultimate outcome of the electrons released during the scintillation process?
They release energy as optical photons
What is the primary function of the focusing electrode in a photomultiplier tube?
To direct the photoelectrons towards the first dynode
What is the ultimate purpose of the cascade procedure in a photomultiplier tube?
To collect all the electrons at the anode
What is the result of the collision between the primary electrons and the first dynode surface?
The liberation of more electrons
What is the purpose of minimizing scattered gamma photons in a gamma camera?
To enhance the produced gamma image quality
What is the nature of the gamma image produced by a conventional gamma camera?
A true mapping of the spatial locations of the detected gamma photons
What is the role of the dynodes in a photomultiplier tube?
To amplify the electrons through a series of stages
What is the final destination of the electrons in a photomultiplier tube?
The anode
What is the typical thickness range of parallel hole collimators manufactured for traditional gamma cameras?
25-80 mm
What is a characteristic of the structure of parallel bore arrays in parallel hole collimators?
Symmetrical with identical holes
What is an advantage of parallel hole collimators compared to pinhole collimators?
Superior level of sensitivity
What is a limitation of collimators in gamma imaging systems?
Most off-axis gamma photons are absorbed
Why do parallel hole collimators allow several incidence angles?
Because the hole diameter is not infinitesimally small
What factor determines the septal thickness in parallel-hole collimators?
Energy of the gamma photons
What is the effect of increasing the hole diameter in parallel hole collimators?
Wider range of acceptance angles
What is the primary reason for minimizing scattered gamma photon penetration in the collimator body?
To avoid the projection of inaccurate data on the gamma image
What is the main difference between parallel hole collimators and non-parallel hole collimators?
Field of view
Which type of collimator is used for scanning small targeted areas, such as brain or cardiac procedures?
Converging collimator
What is the primary purpose of using a diverging collimator?
To collect gamma photons from a large region of interest
What is the typical material used to make a pinhole collimator?
Tungsten, lead, or platinum
What is the diameter range of the aperture in a pinhole collimator?
2-6 mm
What type of collimator is suitable for nuclear medicine clinics with small organ imaging procedures?
Pinhole collimator
What is the advantage of using a pinhole collimator in examining bone joints, paediatric scans, and skeletal extremities?
Enhanced effectiveness
What is the primary difference between parallel hole collimators and pinhole collimators?
Structural shape
Why are non-parallel hole collimators used in nuclear medicine?
To satisfy the needs of specific scanning procedures
What is the primary reason for minimizing scattered gamma photon penetration in the collimator body?
To avoid the projection of inaccurate data on the gamma image
What is the main difference between parallel hole collimators and non-parallel hole collimators?
The hole structure, which affects the field of view
What is the purpose of adjusting the septal thickness in parallel-hole collimators?
To minimize scattered gamma photon penetration
Which type of collimator provides a larger field of view compared to parallel-hole collimators?
Diverging collimator
What is the primary advantage of using pinhole collimators in nuclear medicine clinics?
They are more suitable for small organ imaging procedures
What is the primary advantage of using parallel hole collimators in gamma imaging?
Improved sensitivity due to maximized exposed area of the gamma camera detector
What is the primary factor that determines the appropriate septal thickness in parallel-hole collimators?
Desired level of sensitivity and spatial resolution
What is the main difference between parallel hole collimators and non-parallel hole collimators?
Hole structure and arrangement
What is the effect of increasing the hole diameter in parallel hole collimators?
Improved sensitivity due to increased exposed area
What is the primary reason for minimizing scattered gamma photon penetration in the collimator body?
To reduce scattered gamma photon penetration
What is the main difference between parallel hole collimators and non-parallel hole collimators?
Hole diameter and pattern of arrangement
What determines the septal thickness in parallel-hole collimators?
The hole diameter and pattern of arrangement
What is the primary purpose of the multi-hole collimator in a gamma camera?
To delineate the image from the patient
What is the effect of increasing the hole diameter in parallel hole collimators?
Decreased sensitivity and resolution
What is the primary reason why parallel hole collimators are limited in their field of view?
Most of the off-axis gamma photons are absorbed by the collimator body.
What is the primary reason for minimizing scattered gamma photon penetration in the collimator body?
To reduce the noise and artifacts in the image
What determines the septal thickness in parallel-hole collimators?
The diameter of the collimator holes
What is the primary factor that determines the septal thickness in parallel-hole collimators?
The energy of the gamma photons.
What is the typical field of view in a pinhole collimator?
Small, covering specific targeted structures
What is the effect of increasing the hole diameter in parallel hole collimators?
Increased gamma photon penetration
What is the result of increasing the hole diameter in parallel hole collimators?
The collimator allows a wider range of acceptance angles.
What is a characteristic of large field of view (LFOV) gamma cameras?
They are assembled with diversified hardware and connections
Why do parallel hole collimators provide a superior level of sensitivity compared to pinhole collimators?
Parallel hole collimators allow more gamma photons to pass through.
What is the primary reason for using parallel hole collimators in gamma imaging systems?
To allow for several incidence angles
What is the primary advantage of using parallel hole collimators over non-parallel hole collimators?
Parallel hole collimators provide a superior level of sensitivity.
What is the purpose of medium-energy collimators?
For use up to 400 keV with thicker septa
What is a limitation of conventional planar gamma imaging?
Lack of depth information
What determines the sensitivity of a parallel hole collimator?
Number of holes
What is the purpose of reducing scattered gamma photon penetration in the collimator body?
To reduce sensitivity
What is the advantage of using a non-parallel hole collimator compared to a parallel hole collimator?
Larger field of view
What is the advantage of using a dual- or triple-headed camera in SPECT?
It reduces the image acquisition time or improves the sensitivity
What is the benefit of using an elliptical orbit in SPECT?
It minimizes the gap between the collimator and the patient, improving the resolution
What is the advantage of using three or four gamma cameras equally spaced around the rotating gantry in SPECT?
It improves the sensitivity of the image
How can SPECT studies be presented?
Either as a series of slices or as a three-dimensional display
What is a major use of SPECT?
Both A and B
What is the primary purpose of minimizing scattered gamma photon penetration in parallel-hole collimators?
To improve image resolution
What determines the appropriate septal thickness in parallel-hole collimators?
The energy of the gamma photons
What is the advantage of using non-parallel hole collimators in some applications?
They are more suitable for small organ imaging
What is the effect of increasing the hole diameter in parallel hole collimators?
It increases the sensitivity of the detector
What is the primary difference between parallel hole collimators and non-parallel hole collimators?
The field of view they provide
What is the purpose of adjusting the septal thickness in parallel-hole collimators?
To minimize scattered gamma photon penetration
What is the advantage of using parallel hole collimators in gamma imaging?
They increase the sensitivity of the detector
What is the primary factor that determines the appropriate septal thickness in parallel-hole collimators?
The energy of the gamma photons
What is the primary advantage of using pinhole collimators in nuclear medicine clinics?
They are more suitable for small organ imaging
What is the primary reason for using non-parallel hole collimators in some applications?
They are more suitable for small organ imaging
This quiz is about parallel hole collimators used in gamma cameras, their structure, and characteristics. It covers the thickness, number of holes, and symmetry of these collimators.
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