Gamma Camera Scintillators for Medical Imaging

Why is it important for a scintillator to have a high atomic number?

To reduce the decay time
To enhance imaging performance for clinical use (correct)
To increase refraction index
To minimize the cost

What is a limitation of Sodium Iodide (NaI) scintillators?

High cost
Low light output
Long decay time
Moisture absorption and fragility (correct)

What is the primary reason for sealing NaI crystals in airtight containers?

To reduce their decay time
To increase their light output
To prevent moisture absorption (correct)
To reduce their cost

What is the density of CsI(Na) scintillators?

4.51 g/cm³ (B) Signup and view all the answers

What is the peak emission wavelength of CsI(Tl) scintillators?

540 nm (A) Signup and view all the answers

What is the refraction index of Na(Tl) scintillators?

1.85 (D) Signup and view all the answers

Why is it important for a scintillator to have a short decay time?

To enhance imaging performance (A) Signup and view all the answers

What is the most widely used scintillator in conventional gamma ray imaging systems?

NaI scintillators (C) Signup and view all the answers

What shapes can holes in collimators be manufactured in?

Triangular, square, or circular (D) Signup and view all the answers

What is the typical range of thickness for parallel hole collimators used in traditional gamma cameras?

25-80 mm (A) Signup and view all the answers

What is the structure of parallel bore arrays?

Symmetrical with identical holes (C) Signup and view all the answers

At what angle do incident gamma photons pass through the parallel hole collimator?

Perpendicular angle (A) Signup and view all the answers

What is a benefit of parallel hole collimators compared to pinhole collimators?

Superior level of sensitivity (A) Signup and view all the answers

What happens to off-axis gamma photons in gamma imaging systems?

They are absorbed by the collimator body (B) Signup and view all the answers

Why do larger hole diameters in parallel hole collimators degrade spatial resolution?

Because they allow a wider range of acceptance angles (B) Signup and view all the answers

What is a key factor in determining the septal thickness of a parallel-hole collimator?

The energy of the gamma photons (B) Signup and view all the answers

What is the use of medium-energy collimators?

Up to 400 keV (B) Signup and view all the answers

What is the limitation of conventional planar gamma imaging?

Loss of depth information (B) Signup and view all the answers

What are the two methods of emission tomography?

SPECT and PET (C) Signup and view all the answers

What is the function of a parallel hole collimator in SPECT?

To acquire views from different directions (C) Signup and view all the answers

How many views are taken in a SPECT scan?

60 views (A) Signup and view all the answers

What is the approximate total scanning time for a SPECT scan?

30 minutes (B) Signup and view all the answers

How many counts are acquired in a SPECT scan?

3 million counts (A) Signup and view all the answers

What is the purpose of emission tomography?

To improve contrast and regain depth information (A) Signup and view all the answers

What is the benefit of using a dual- or triple-headed camera in SPECT?

Halved image acquisition time or improved sensitivity (B) Signup and view all the answers

What is the purpose of using an elliptical orbit in SPECT?

To minimize the gap between the collimator and the patient (D) Signup and view all the answers

What is a useful option for cardiac tomography in SPECT?

180° rotation (A) Signup and view all the answers

What can be done with the increased sensitivity in SPECT?

Increase patient throughput or improve resolution (D) Signup and view all the answers

How can SPECT studies be presented?

Either as a series of slices or as a 3-D display (A) Signup and view all the answers

What makes the 3-D display particularly effective in SPECT?

Persistence of vision (D) Signup and view all the answers

What is a major use of SPECT?

Thallium studies of myocardial infarctions and ischaemia (D) Signup and view all the answers

What is another major use of SPECT?

Quantitative cerebral blood flow (B) Signup and view all the answers

What is the required pinhole diameter for small animal gamma imaging systems?

1-2 mm (D) Signup and view all the answers

What is the purpose of using a non-parallel hole collimator?

To improve the spatial resolution (B) Signup and view all the answers

What is the characteristic of a low-energy collimator?

Thin septa and high sensitivity (B) Signup and view all the answers

What is the resolution of a general purpose collimator at 10 cm from the face?

9 mm (B) Signup and view all the answers

What is the characteristic of a high-resolution collimator?

More and smaller holes (B) Signup and view all the answers

What is the trade-off of using a high-resolution collimator?

Lower sensitivity (A) Signup and view all the answers

What is the characteristic of a high-sensitivity collimator?

Fewer and larger holes (B) Signup and view all the answers

What is the consequence of using a high-sensitivity collimator?

Lower resolution (B) Signup and view all the answers

What is the main reason for using a medium-energy collimator?

To image radionuclides with energy up to 400 keV (C) Signup and view all the answers

What is the primary limitation of conventional planar gamma imaging?

Insufficient depth information (C) Signup and view all the answers

What is the purpose of rotating the gamma camera in SPECT imaging?

To acquire views from different directions (B) Signup and view all the answers

What is the main difference between SPECT and PET imaging?

SPECT acquires single-photon emissions, while PET acquires positron emissions (B) Signup and view all the answers

What is the purpose of emission tomography in radionuclide imaging?

To provide depth information and improve contrast (A) Signup and view all the answers

What is the primary function of a multi-hole collimator in gamma imaging?

To delineate the image from the patient (C) Signup and view all the answers

What is the role of a scintillation crystal in gamma imaging?

To convert gamma rays into optical light (C) Signup and view all the answers

What is the result of gamma rays being detected by a gamma camera?

A graphical representation of the radioactive distribution is created (D) Signup and view all the answers

What is the purpose of a gamma camera in medical imaging?

To produce a medical gamma image (B) Signup and view all the answers

What is the energy of the gamma rays emitted by the radionuclide 99mTc?

141keV (A) Signup and view all the answers

What is the typical thickness range for scintillators in gamma cameras?

6 to 12.5 mm (D) Signup and view all the answers

What happens when gamma photons interact with the scintillation crystal?

The energy is deposited and converted to visible optical photons (B) Signup and view all the answers

What is the role of the photomultiplier tube (PMT) in gamma detection?

To convert optical photons into an electrical signal (C) Signup and view all the answers

What is the wavelength of optical photons transmitted by the NaI scintillator?

415 nm (A) Signup and view all the answers

What is the relationship between the electric current and the number of detected optical photons in a PMT?

Directly proportional (D) Signup and view all the answers

What is the benefit of using a dual- or triple-headed camera in SPECT?

Reduced image acquisition time or improved sensitivity (B) Signup and view all the answers

Why is an elliptical orbit sometimes used in SPECT?

To minimize the gap between the collimator and the patient (A) Signup and view all the answers

How can SPECT studies be presented?

Either as a series of slices or as a three-dimensional display (B) Signup and view all the answers

What is a useful option for cardiac tomography in SPECT?

A 180° rotation (B) Signup and view all the answers

What can be done with the increased sensitivity in SPECT?

Use the increased sensitivity for faster patient throughput or to improve the resolution (D) Signup and view all the answers

What is the purpose of a dynode in a photomultiplier tube?

To amplify the electrons produced by the photocathode (C) Signup and view all the answers

What is the result of the collision between the primary electrons and the dynode surface in a photomultiplier tube?

The liberation of more electrons (D) Signup and view all the answers

What is the purpose of minimizing scattered gamma photons in gamma imaging?

To reduce the noise in the gamma image (D) Signup and view all the answers

What is the outcome of the cascade procedure in a photomultiplier tube?

The collection of electrons at the anode (C) Signup and view all the answers

What is formed on a pixelated grid in a conventional gamma camera?

A gamma image (C) Signup and view all the answers

What is the purpose of quality control in radiopharmaceuticals?

To ensure the correct labelling of compounds (C) Signup and view all the answers

What is the primary function of the radiopharmaceutical in planar imaging?

To concentrate in the organ or tissues of interest (B) Signup and view all the answers

What is tested during quality control for radionuclide purity?

Contamination with 99Mo (B) Signup and view all the answers

What is the purpose of the dose calibrator?

To calibrate the detector against a standard source (D) Signup and view all the answers

What is the benefit of using an automated synthesis device for PET tracers' production?

Reduces the radiation exposure of staff (B) Signup and view all the answers

What is the effect of using thick crystals in scintillators?

Higher sensitivity levels (B) Signup and view all the answers

What occurs when incident gamma photons interact with the scintillator material?

An energetic electron is released (A) Signup and view all the answers

What is a key factor influencing the scintillation process?

Crystal design (A) Signup and view all the answers

What happens to the electrons in an excited state in the scintillator?

They return to their stable state, releasing energy as optical photons (D) Signup and view all the answers

What is the result of Compton scattering interactions in the scintillator?

The release of energetic electrons (C) Signup and view all the answers

What influences the type of collimator used in nuclear scanning?

Desired level of sensitivity and spatial resolution (A) Signup and view all the answers

What is the main drawback of using collimators in gamma imaging?

Gamma photons passing through the collimator’s holes only can be registered (B) Signup and view all the answers

What is the typical structure of parallel hole collimators?

Hexagonal structured holes in a close-packed hexagonal array (C) Signup and view all the answers

What is the benefit of using a parallel hole collimator in gamma imaging?

Maximisation of exposed area of the gamma camera detector (C) Signup and view all the answers

What is the primary goal of emission tomography in radionuclide imaging?

To produce a 3D image of the body (B) Signup and view all the answers

What is a major application of SPECT imaging?

Cardiac tomography (A) Signup and view all the answers

How does the parallel hole collimator differ from other collimators?

It has hexagonal structured holes (D) Signup and view all the answers

What is the advantage of using a high-density material plate in parallel hole collimators?

Higher absorption of gamma rays (C) Signup and view all the answers

What influences the design of collimators in gamma imaging?

Desired level of sensitivity and spatial resolution (D) Signup and view all the answers

What is the benefit of using a scintillator in gamma imaging?

It converts gamma rays to visible light (C) Signup and view all the answers

Gamma Camera Scintillators for Medical Imaging

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Questions and Answers

Why is it important for a scintillator to have a high atomic number?

What is a limitation of Sodium Iodide (NaI) scintillators?

What is the primary reason for sealing NaI crystals in airtight containers?

What is the density of CsI(Na) scintillators?

What is the peak emission wavelength of CsI(Tl) scintillators?

What is the refraction index of Na(Tl) scintillators?

Why is it important for a scintillator to have a short decay time?

What is the most widely used scintillator in conventional gamma ray imaging systems?

What shapes can holes in collimators be manufactured in?

What is the typical range of thickness for parallel hole collimators used in traditional gamma cameras?

What is the structure of parallel bore arrays?

At what angle do incident gamma photons pass through the parallel hole collimator?

What is a benefit of parallel hole collimators compared to pinhole collimators?

What happens to off-axis gamma photons in gamma imaging systems?

Why do larger hole diameters in parallel hole collimators degrade spatial resolution?

What is a key factor in determining the septal thickness of a parallel-hole collimator?

What is the use of medium-energy collimators?

What is the limitation of conventional planar gamma imaging?

What are the two methods of emission tomography?

What is the function of a parallel hole collimator in SPECT?

How many views are taken in a SPECT scan?

What is the approximate total scanning time for a SPECT scan?

How many counts are acquired in a SPECT scan?

What is the purpose of emission tomography?

What is the benefit of using a dual- or triple-headed camera in SPECT?

What is the purpose of using an elliptical orbit in SPECT?

What is a useful option for cardiac tomography in SPECT?

What can be done with the increased sensitivity in SPECT?

How can SPECT studies be presented?

What makes the 3-D display particularly effective in SPECT?

What is a major use of SPECT?

What is another major use of SPECT?

What is the required pinhole diameter for small animal gamma imaging systems?

What is the purpose of using a non-parallel hole collimator?

What is the characteristic of a low-energy collimator?

What is the resolution of a general purpose collimator at 10 cm from the face?

What is the characteristic of a high-resolution collimator?

What is the trade-off of using a high-resolution collimator?

What is the characteristic of a high-sensitivity collimator?

What is the consequence of using a high-sensitivity collimator?

What is the main reason for using a medium-energy collimator?

What is the primary limitation of conventional planar gamma imaging?

What is the purpose of rotating the gamma camera in SPECT imaging?

What is the main difference between SPECT and PET imaging?

What is the purpose of emission tomography in radionuclide imaging?

What is the primary function of a multi-hole collimator in gamma imaging?

What is the role of a scintillation crystal in gamma imaging?

What is the result of gamma rays being detected by a gamma camera?

What is the purpose of a gamma camera in medical imaging?

What is the energy of the gamma rays emitted by the radionuclide 99mTc?

What is the typical thickness range for scintillators in gamma cameras?

What happens when gamma photons interact with the scintillation crystal?

What is the role of the photomultiplier tube (PMT) in gamma detection?

What is the wavelength of optical photons transmitted by the NaI scintillator?

What is the relationship between the electric current and the number of detected optical photons in a PMT?

What is the benefit of using a dual- or triple-headed camera in SPECT?

Why is an elliptical orbit sometimes used in SPECT?

How can SPECT studies be presented?

What is a useful option for cardiac tomography in SPECT?

What can be done with the increased sensitivity in SPECT?

What is the purpose of a dynode in a photomultiplier tube?

What is the result of the collision between the primary electrons and the dynode surface in a photomultiplier tube?

What is the purpose of minimizing scattered gamma photons in gamma imaging?

What is the outcome of the cascade procedure in a photomultiplier tube?

What is formed on a pixelated grid in a conventional gamma camera?

What is the purpose of quality control in radiopharmaceuticals?

What is the primary function of the radiopharmaceutical in planar imaging?

What is tested during quality control for radionuclide purity?

What is the purpose of the dose calibrator?

What is the benefit of using an automated synthesis device for PET tracers' production?

What is the effect of using thick crystals in scintillators?

What occurs when incident gamma photons interact with the scintillator material?

What is a key factor influencing the scintillation process?

What happens to the electrons in an excited state in the scintillator?

What is the result of Compton scattering interactions in the scintillator?

What influences the type of collimator used in nuclear scanning?