Gamma Camera Resolution and Collimators Quiz
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Questions and Answers

What type(s) of radiation are being measured when a Geiger counter is used to measure a radioactive source with its cover removed?

  • Beta particles only
  • Gamma rays only
  • Alpha particles only
  • Beta/alpha particles and gamma rays (correct)

    • What do radiation interactions in a gas-filled detector create?

  • Positive electrons and negative ions
  • Positive ions and negative electrons
  • Protons and neutrons
  • Negative electrons and positive ions (correct)

    • Where do the negative electrons migrate to in a gas-filled detector?

  • Anode (correct)
  • Electrically charged plates
  • Cathode
  • Gas space

    • According to the standard of practice, what should the percent energy resolution fall between for Cs137?

    <p>10%-20%</p> Signup and view all the answers

    If the energy spread for Cs137 is 635 keV to 689 keV at half-maximum, does the instrument have an acceptable percent energy resolution?

    <p>8.2%</p> Signup and view all the answers

    Where is the region of operation on the voltage-response curve for a Geiger counter?

    <p>Geiger muller region</p> Signup and view all the answers

    Does pulse mode operation of a gas-filled detector require a high photon flux to produce an accurate reading?

    <p>False</p> Signup and view all the answers

    What is the function of a collimator?

    <p>Absorbs gamma rays going at undesirable angles</p> Signup and view all the answers

    What is the most important factor in determining the appropriate matrix size for a digital image?

    <p>Resolution</p> Signup and view all the answers

    Which of the following is the main difference between an all-purpose and a high-resolution collimator?

    <p>Hole diameter</p> Signup and view all the answers

    What is the function of a pulse height analyzer?

    <p>Determines if an event's energy falls within the energy window</p> Signup and view all the answers

    Which of the following can be used as the stopping condition for a gamma camera image?

    <p>Information density</p> Signup and view all the answers

    True or False: Septal penetration is more of a problem with higher-energy gamma rays than lower-energy gamma rays.

    <p>True</p> Signup and view all the answers

    What is the appropriate collimator if we want high-quality images of the bones of the hand?

    <p>High resolution</p> Signup and view all the answers

    What is the function of a scintillation crystal?

    <p>Absorbs gamma rays and creates scintillation photons.</p> Signup and view all the answers

    What is the purpose of a photomultiplier tube in a scintillation detector?

    <p>Convert the scintillation into an electric signal.</p> Signup and view all the answers

    What is the minimum time separation required between two radiation events in order for them to be detected as two separate events?

    <p>Dead time</p> Signup and view all the answers

    Which type of collimator has better resolution at the same object-collimator distance?

    <p>Parallel-hole collimator</p> Signup and view all the answers

    What mainly determines a gamma camera’s extrinsic resolution?

    <p>Resolution of the collimator being used</p> Signup and view all the answers

    Which of the following will improve image contrast?

    <p>Decreased object-collimator distance</p> Signup and view all the answers

    In filtered backprojection, how does the filter work in the reconstruction?

    <p>By modifying the amplitude of the spatial frequencies used in the reconstruction</p> Signup and view all the answers

    In which SPECT study is it acceptable to acquire with a 180º orbit?

    <p>Heart imaging</p> Signup and view all the answers

    Which semiconductor material is used in commercial intraoperative probes?

    <p>Cadmium zinc telluride (CZT)</p> Signup and view all the answers

    What is the purpose of the photomultiplier tube in a scintillation detector?

    <p>To convert the scintillation photons into an electronic signal</p> Signup and view all the answers

    "Scintillators used for PET have different strengths. BGO has high stopping power for 511 keV photons and therefore maximizes the ________ detected." Fill in the blank.

    <p>Total number of coincidences</p> Signup and view all the answers

    "Scintillators used for PET have different strengths. LSO has a short decay time, reducing the number of ________." Fill in the blank.

    <p>&quot;Random coincidences&quot;</p> Signup and view all the answers

    Select the correct incidence type:

    <p>Scatter event</p> Signup and view all the answers

    In PET scans using CT corrections, is a single correction factor used for all tissues?

    <p>False</p> Signup and view all the answers

    Is an area of increased activity on the non-attenuation-corrected PET scan always a real hot spot?

    <p>False</p> Signup and view all the answers

    What type of magnets are generally used in clinical MRI tomographs?

    <p>Superconducting magnets</p> Signup and view all the answers

    What is required for creating an MR image?

    <p>Atoms with an unpaired proton</p> Signup and view all the answers

    Is it necessary to administer DTPA in a room with negative pressure?

    <p>False</p> Signup and view all the answers

    Is Xe 133 gas administered by use of a nebulizer?

    <p>False</p> Signup and view all the answers

    What type(s) of radiation are being measured when a Geiger counter is used to measure a radioactive source with its cover removed?

    <p>Beta/alpha particles and gamma rays</p> Signup and view all the answers

    'Baseline shift' and 'pulse pile-up' are most likely to occur in situations with:

    <p>High counting rates</p> Signup and view all the answers

    'Dead time' is the minimum time separation between two radiation events that is required for them to be detected as two separate events. Is this statement:

    <p>True</p> Signup and view all the answers

    Which of the following will improve image contrast?

    <p>Decreased object-collimator distance</p> Signup and view all the answers

    What kind of radiation is being measured when a Geiger counter is used to measure a radioactive source with its cover removed?

    <p>Gamma rays</p> Signup and view all the answers

    What do radiation interactions in a gas-filled detector create?

    <p>Negative electrons and positive ions</p> Signup and view all the answers

    Where do the negative electrons migrate to in a gas-filled detector?

    <p>Cathode</p> Signup and view all the answers

    True or False: Pulse mode operation of a gas-filled detector requires a high photon flux to produce an accurate reading.

    <p>True</p> Signup and view all the answers

    When a CT scan is used to correct for attenuation in a PET scan, is a single correction factor used for all tissues?

    <p>False</p> Signup and view all the answers

    Is it always true that an area of increased activity on the non-attenuation-corrected PET scan is a real hot spot?

    <p>False</p> Signup and view all the answers

    Is it necessary to administer Xe 133 gas by use of a nebulizer?

    <p>False</p> Signup and view all the answers

    Will baseline shift and pulse pile-up most likely occur in situations with high counting rates?

    <p>False</p> Signup and view all the answers

    Which type of collimator has better resolution at the same object-collimator distance?

    <p>Parallel-hole collimator</p> Signup and view all the answers

    What mainly determines a gamma camera’s extrinsic resolution?

    <p>Resolution of the collimator being used</p> Signup and view all the answers

    Which of the following will degrade contrast?

    <p>Decreased object-collimator distance</p> Signup and view all the answers

    In filtered backprojection, how does the filter work in the reconstruction?

    <p>It modifies the amplitude of the spatial frequencies used in the reconstruction</p> Signup and view all the answers

    Which semiconductor material is used in commercial intraoperative probes?

    <p>Cadmium Zinc Telluride (CZT)</p> Signup and view all the answers

    What is the purpose of the photomultiplier tube in a scintillation detector?

    <p>To amplify the radiation signal</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. LSO has a short decay time, reducing the number of ________.' Fill in the blank.

    <p>Prompt events</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. GSO, with its improved energy resolution, allows for a greater exclusion of ____________.' Fill in the blank.

    <p>Scatter coincidence</p> Signup and view all the answers

    In which of the following SPECT studies is it acceptable to acquire with a 180º orbit?

    <p>Heart</p> Signup and view all the answers

    True or false: In transmission imaging, one measures photons from an external source that pass through the object.

    <p>True</p> Signup and view all the answers

    True or false: As many as half of all counts in a SPECT study may have been scattered before being registered in the gamma camera.

    <p>True</p> Signup and view all the answers

    Which of the following contributes the most to dead time?

    <p>Prompt events</p> Signup and view all the answers

    What is the purpose of a pulse height analyzer in a scintillation detector?

    <p>Identifies pulses within the energy window</p> Signup and view all the answers

    Which of the following materials is used in commercial intraoperative probes?

    <p>CZT</p> Signup and view all the answers

    What function does a collimator serve in a gamma camera?

    <p>Absorbs gamma rays going at undesirable angles</p> Signup and view all the answers

    Which of the following is a disadvantage of a digital image?

    <p>It is aesthetically more pleasing than an analog image</p> Signup and view all the answers

    What is the function of a light pipe in the context of a gamma camera?

    <p>Improves uniformity of gamma camera flood image</p> Signup and view all the answers

    What will improve the collimator's overall sensitivity?

    <p>Increasing the hole length</p> Signup and view all the answers

    Which type of collimator would be suitable if part of the body being imaged is small compared to the camera’s field of view?

    <p>Converging</p> Signup and view all the answers

    What is the main cause of non-uniformity in a gamma camera?

    <p>PMTs</p> Signup and view all the answers

    What determines a gamma camera's extrinsic resolution primarily?

    <p>The distance between the collimator and the object being imaged</p> Signup and view all the answers

    What function does a position circuit serve?

    <p>Determines the position of an event</p> Signup and view all the answers

    True or False: Septal penetration is more of a problem with lower-energy gamma rays than higher-energy gamma rays.

    <p>False</p> Signup and view all the answers

    What type(s) of radiation are being measured when a Geiger counter is used to measure a radioactive source with its cover removed?

    <p>Beta particles and gamma rays</p> Signup and view all the answers

    Which region of operation on the voltage-response curve is associated with a Geiger counter?

    <p>Geiger muller region</p> Signup and view all the answers

    What causes the change in charge on one or both plates of a gas-filled detector?

    <p>Migration of positive ions and negative electrons</p> Signup and view all the answers

    Which type of gas-filled detector requires a high photon flux for accurate readings in pulse mode operation?

    <p>Geiger counter</p> Signup and view all the answers

    What primarily determines a gamma camera's extrinsic resolution?

    <p>Collimator design</p> Signup and view all the answers

    What is the purpose of the photomultiplier tube in a scintillation detector?

    <p>To amplify the light signals from the scintillation crystal</p> Signup and view all the answers

    'Dead time' is the minimum time separation between two radiation events that is required for them to be detected as two separate events. Is this statement:

    <p>True</p> Signup and view all the answers

    True or False: In transmission imaging, one measures photons from an external source that pass through the object.

    <p>True</p> Signup and view all the answers

    According to the standard of practice, what should the percent energy resolution fall between for Cs137?

    <p>10%-20%</p> Signup and view all the answers

    What is the minimum time separation required between two radiation events in order for them to be detected as two separate events?

    <p>100 ns</p> Signup and view all the answers

    Which of the following can be used as the stopping condition for a gamma camera image?

    <p>All of the above</p> Signup and view all the answers

    What mainly determines a gamma camera’s extrinsic resolution?

    <p>Intrinsic resolution of the collimator</p> Signup and view all the answers

    Which type of collimator has better resolution at the same object-collimator distance?

    <p>Diverging</p> Signup and view all the answers

    What is the function of a pulse height analyzer?

    <p>Determines if an event's energy falls within the energy window</p> Signup and view all the answers

    Which of the following materials is used in commercial intraoperative probes?

    <p>CZT</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. BGO has high stopping power for 511 keV photons and therefore maximizes the ________ detected.' Fill in the blank.

    <p>Absorption fraction</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. GSO, with its improved energy resolution, allows for a greater exclusion of ____________.' Fill in the blank.

    <p>Scatter fraction</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. LSO has a short decay time, reducing the number of ________.' Fill in the blank.

    <p>Scatter fraction</p> Signup and view all the answers

    Which of the following will improve image contrast?

    <p>Decreased object-collimator distance</p> Signup and view all the answers

    In which of the following SPECT studies is it acceptable to acquire with a 180º orbit?

    <p>Heart</p> Signup and view all the answers

    Which of the following does NOT degrade contrast?

    <p>Greater count density</p> Signup and view all the answers

    True or false? In transmission imaging, one measures photons from an external source that pass through the object.

    <p>True</p> Signup and view all the answers

    Which of the following semiconductor materials is used in commercial intraoperative probes?

    <p>CZT</p> Signup and view all the answers

    The purpose of the photomultiplier tube in a scintillation detector is to:

    <p>Convert the scintillation photons into an electronic signal</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. LSO has a short decay time, reducing the number of ________.' Fill in the blank.

    <p>Prompt events</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. BGO has high stopping power for 511 keV photons and therefore maximizes the ________ detected.' Fill in the blank.

    <p>Total number of coincidences</p> Signup and view all the answers

    'Scintillators used for PET have different strengths. GSO, with its improved energy resolution, allows for a greater exclusion of ____________.' Fill in the blank.

    <p>Scatter coincidences</p> Signup and view all the answers

    True or false? Attenuation is more of a problem with PET than it is with single-photon imaging.

    <p>True</p> Signup and view all the answers

    Which of the following is NOT true about the use of a CT scan to correct for attenuation in a PET scan?

    <p>A single correction factor can be used for all tissues</p> Signup and view all the answers

    Is it always true that an area of increased activity on the non-attenuation-corrected PET scan is a real hot spot?

    <p>No</p> Signup and view all the answers

    What type of magnets are generally used in clinical MRI tomographs?

    <p>Superconducting magnets</p> Signup and view all the answers

    True or false: DTPA administration must be done in a room with negative pressure?

    <p>False</p> Signup and view all the answers

    True or false: Xe 133 gas is administered by use of a nebulizer?

    <p>False</p> Signup and view all the answers

    When a Geiger counter is used to measure a radioactive source and its cover is removed, what type(s) of radiation are being measured?

    <p>Beta, alpha particles, and gamma rays</p> Signup and view all the answers

    'Baseline shift' and 'pulse pile-up' are most likely to occur in situations with:

    <p>High counting rates</p> Signup and view all the answers

    'Dead time' is the minimum time separation between two radiation events that is required for them to be detected as two separate events. Is this statement:

    <p>True</p> Signup and view all the answers

    Which of the following will improve image contrast?

    <p>Use of 2D projections to make a 3D matrix and derive 2D slices</p> Signup and view all the answers

    'Creating an MR image requires: Atoms with an unpaired proton.' True or false?

    <p>False</p> Signup and view all the answers

    In PET scans using CT corrections, is a single correction factor used for all tissues?

    <p>True</p> Signup and view all the answers

    Is it necessary to administer Xe 133 gas by use of a nebulizer?

    <p>False</p> Signup and view all the answers

    Will baseline shift and pulse pile-up most likely occur in situations with low counting rates?

    <p>False</p> Signup and view all the answers

    Is it always true that an area of increased activity on the non-attenuation-corrected PET scan is a real hot spot?

    <p>False</p> Signup and view all the answers

    Does pulse mode operation of a gas-filled detector require a high photon flux to produce an accurate reading?

    <p>True</p> Signup and view all the answers

    What determines a gamma camera's extrinsic resolution primarily?

    <p>Collimator design</p> Signup and view all the answers

    What kind of radiation is being measured when a Geiger counter is used to measure a radioactive source with its cover removed?

    <p>Beta/alpha particles and gamma rays</p> Signup and view all the answers

    Which of the following contributes the most to dead time?

    <p>Pulse generation time</p> Signup and view all the answers

    Which of the following will degrade contrast?

    <p>Low counting rates.</p> Signup and view all the answers

    Study Notes

    Radiation Measurement and Detectors

    • When a Geiger counter is used to measure a radioactive source with its cover removed, it measures alpha, beta, and gamma radiation.
    • In a gas-filled detector, radiation interactions create ion pairs.
    • In a gas-filled detector, negative electrons migrate to the anode.

    Pulse Height Analyzer and Collimators

    • A pulse height analyzer is used to analyze the energy spectrum of radiation.
    • A collimator is used to restrict the angle of incidence of radiation on a detector.
    • A high-resolution collimator has smaller holes and is used for high-quality images of small objects.

    Gamma Cameras and SPECT

    • The extrinsic resolution of a gamma camera is mainly determined by the collimator.
    • A 180º orbit is acceptable for some SPECT studies.
    • In filtered backprojection, the filter works in the reconstruction to reduce noise.

    Scintillators and PET

    • BGO has high stopping power for 511 keV photons, maximizing detection.
    • LSO has a short decay time, reducing the number of random coincidences.
    • GSO has improved energy resolution, allowing for a greater exclusion of scattered photons.

    Image Contrast and Resolution

    • High-energy gamma rays are more susceptible to septal penetration.
    • A high-resolution collimator and a large matrix size can improve image contrast.
    • Dead time is the minimum time separation between two radiation events required to detect them as separate events.

    MRI and X-Ray

    • Clinical MRI tomographs use superconducting magnets.
    • DTPA administration does not require a room with negative pressure.
    • Xe 133 gas is administered using a nebulizer.

    Miscellaneous

    • Pulse mode operation of a gas-filled detector requires a high photon flux to produce an accurate reading.
    • Baseline shift and pulse pile-up occur in situations with high counting rates.
    • A position circuit serves to determine the position of radiation detection events.
    • A light pipe is used to transmit light from the scintillator to the photomultiplier tube in a gamma camera.

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    Description

    Test your knowledge on gamma camera resolution and collimators with this quiz. Determine whether statements about pinhole and parallel-hole collimators, as well as the extrinsic resolution of a gamma camera, are true or false. Additionally, identify components of background counts in nuclear medicine images.

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