PET Iterative Reconstruction and Image Artifacts Quiz
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PET Iterative Reconstruction and Image Artifacts Quiz

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Questions and Answers

In coincidence imaging, what is the essential requirement for the detection of annihilation photons?

  • They must be detected in the same detector
  • They must be detected within a long timing window
  • They must be detected in opposite detectors within a short timing window (correct)
  • They must be detected without using a Coincidence Timing Circuit

    • What happens to the annihilation photons if they are not determined to be in coincidence during a PET scan?

  • They are used for creating PET images
  • They are discarded (correct)
  • They are added to image memory
  • They are sent to the Coincidence Timing Circuit again

    • Which radionuclide is NOT cyclotron produced and is used for Myocardial perfusion imaging?

  • F-18
  • O-15
  • C-11
  • Rb-82 (correct)

    • What is the energy of the annihilation photons emitted from positron-emitting radionuclides?

    <p>511 keV</p> Signup and view all the answers

    What is the role of the Pulse Height Analyzer in coincidence imaging?

    <p>Identifying the annihilation photons</p> Signup and view all the answers

    Why is it necessary for the annihilation photons to be detected by both detectors on each side during coincidence imaging?

    <p>To reduce the chances of false coincidences</p> Signup and view all the answers

    What is the important characteristic of the scintillation materials used for coincidence imaging?

    <p>High sensitivity to 511 keV photons</p> Signup and view all the answers

    What is the chief benefit of time-of-flight (TOF) technology in PET imaging?

    <p>Improved signal-to-noise ratio (SNR)</p> Signup and view all the answers

    Which factor has a significant impact on the standardized uptake value (SUV) for FDG in PET imaging?

    <p>Uptake in other tissues</p> Signup and view all the answers

    How do the annihilation photons differ from the positron emission in terms of location?

    <p>They are emitted 180º opposed from the positron emission location</p> Signup and view all the answers

    What is the primary purpose of the filter in an x-ray tube used in CT imaging?

    <p>To remove low-energy x-rays from the beam</p> Signup and view all the answers

    In PET imaging, what is the consequence of dead time?

    <p>Loss of true coincidence</p> Signup and view all the answers

    What is the main limitation of annihilation photon imaging in PET?

    <p>Resolution variation with radionuclide used</p> Signup and view all the answers

    What type of image looks very different from non-attenuation corrected images in PET?

    <p>Attenuation corrected image</p> Signup and view all the answers

    Which concept in CT imaging involves the table moving through the gantry as the gantry rotates around the table?

    <p>Helical scanning</p> Signup and view all the answers

    What type of x-rays are selectively removed by the filter in an x-ray tube used in CT imaging?

    <p>'Soft' x-rays</p> Signup and view all the answers

    What is the range of units of attenuation in a CT study, expressed relative to the attenuation of water?

    <p>-1000 to +3000</p> Signup and view all the answers

    What type of radiation does MRI use to generate detailed images of internal structures?

    <p>Radiofrequency pulses</p> Signup and view all the answers

    What type of gas filled administration requires a negative pressure room?

    <p>Xe 133</p> Signup and view all the answers

    What is used to make the liquid DTPA a breathable aerosol in aerosol administration?

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

    What is used to absorb the Xenon gas during the washout phase in gas administration?

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

    What is the main advantage of MRI over CT in terms of imaging?

    <p>Suitable for soft tissue imaging</p> Signup and view all the answers

    In a CT study, what is the range of attenuation units for air?

    <p>-1000</p> Signup and view all the answers

    What does CT employ to create cross-sectional images of the body?

    <p>X-rays</p> Signup and view all the answers

    What are the approximate CT number ranges for air, soft tissue, and bone?

    <p>Air: -1000, Soft tissue: -200 - +200, Bone: +300 - +1000</p> Signup and view all the answers

    What is the biggest contributor to dead time in PET/CT imaging?

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

    What does the term 'scatter incidents' refer to in nuclear medicine imaging?

    <p>The phenomenon where gamma rays deviate after interacting with tissues in the patient's body</p> Signup and view all the answers

    What is the purpose of shimming coils in an MRI scanner?

    <p>To optimize the homogeneity of the magnetic field</p> Signup and view all the answers

    What is the function of RF coils in an MRI scanner?

    <p>To transmit radiofrequency pulses into the body</p> Signup and view all the answers

    What refers to the ability of an imaging system to detect and accurately measure the gamma rays emitted by radioactive tracers administered to a patient?

    <p>System sensitivity</p> Signup and view all the answers

    How does pitch change the amount of radiation a patient is exposed to in CT imaging?

    <p>Higher pitch decreases radiation exposure</p> Signup and view all the answers

    What uses a 2D projection to make a 3D image in nuclear medicine imaging?

    <p>&quot;Iterative Reconstruction&quot;</p> Signup and view all the answers

    What is the main reason for attenuation being more of a problem in PET than in SPECT?

    <p>The requirement that both annihilation photons be detected</p> Signup and view all the answers

    In PET imaging, what is the purpose of time of flight (TOF) technology?

    <p>To measure the time difference between the detection of two gamma rays</p> Signup and view all the answers

    What distinguishes 2D PET imaging from 3D PET imaging in terms of sensitivity to random and scatter coincidences?

    <p>3D imaging has higher sensitivity to random coincidences</p> Signup and view all the answers

    What component is used in 2D PET imaging to absorb cross plane annihilation photons and improve image quality?

    <p>Tungsten septa</p> Signup and view all the answers

    How are randoms corrected in PET imaging using the delayed coincidence sinogram method?

    <p>By holding each event for several CTWs, then regenerating the signal</p> Signup and view all the answers

    What is the main purpose of a sinogram in PET imaging?

    <p>To identify line of response (LOR) between coincident events</p> Signup and view all the answers

    What is the essential requirement for event detection in PET imaging?

    <p>Detection of two annihilation photons within the coincidence timing window (CTW) and in two blocks allowed to be in coincidence</p> Signup and view all the answers

    What characteristic contributes to noise in PET images from a per-voxel viewpoint?

    <p>'Random and scatter count rates'</p> Signup and view all the answers

    What is the scintillation crystal with the highest detection efficiency but has a long decay time and low scintillation light yield?

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

    In coincidence imaging, what represents a true coincidence event?

    <p>Two annihilation photons from a single annihilation interaction detected within the CTW</p> Signup and view all the answers

    Why is attenuation more of a problem in PET than in SPECT?

    <p>PET requires both annihilation photons to be detected</p> Signup and view all the answers

    What is the main purpose of Time of Flight (TOF) technology in PET imaging?

    <p>To improve spatial resolution of the reconstructed image</p> Signup and view all the answers

    What distinguishes PET as more quantitative than SPECT?

    <p>PET allows measurement of physiologic quantities in vivo</p> Signup and view all the answers

    Which type of coincidence originates from a single annihilation interaction and represents a true coincidence event?

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

    How is a sinogram used to evaluate motion in PET imaging?

    <p>By evaluating motion through stacking rows from each projection in a 2D image matrix</p> Signup and view all the answers

    What is the essential requirement for the detection of annihilation photons in coincidence imaging?

    <p>Detection by both detectors on each side</p> Signup and view all the answers

    What is the function of the Pulse Height Analyzer in coincidence imaging?

    <p>Determining if annihilation photons are in coincidence</p> Signup and view all the answers

    What distinguishes PET as more quantitative than SPECT?

    <p>Ability to detect single annihilation interactions</p> Signup and view all the answers

    What is the chief benefit of time-of-flight (TOF) technology in PET imaging?

    <p>Improved spatial resolution</p> Signup and view all the answers

    What characteristic contributes to noise in PET images from a per-voxel viewpoint?

    <p>Attenuation correction errors</p> Signup and view all the answers

    What does the term 'scatter incidents' refer to in nuclear medicine imaging?

    <p>Deflection of annihilation photons from their original path</p> Signup and view all the answers

    What is used to absorb the Xenon gas during the washout phase in gas administration?

    <p>Charcoal filter</p> Signup and view all the answers

    What component is used in 2D PET imaging to absorb cross plane annihilation photons and improve image quality?

    <p>Lead septa</p> Signup and view all the answers

    How are randoms corrected in PET imaging using the delayed coincidence sinogram method?

    <p>By subtracting the delayed coincidence events</p> Signup and view all the answers

    What type of gas filled administration requires a negative pressure room?

    <p>Xenon gas administration</p> Signup and view all the answers

    What is the main purpose of the Coincidence Timing Circuit in coincidence imaging?

    <p>To determine if the annihilation photons are in coincidence</p> Signup and view all the answers

    Which component is responsible for identifying the annihilation photons in coincidence imaging?

    <p>Pulse Height Analyzer</p> Signup and view all the answers

    What characteristic differentiates the location of annihilation from the location of positron emission?

    <p>They differ slightly in location</p> Signup and view all the answers

    Which radionuclide is used for Myocardial perfusion imaging and is NOT cyclotron produced?

    <p>Rb-82</p> Signup and view all the answers

    What is the energy of the annihilation photons emitted from positron-emitting radionuclides?

    <p>$511 keV$</p> Signup and view all the answers

    What is the main advantage of time-of-flight (TOF) technology in PET imaging?

    <p>Improved spatial resolution</p> Signup and view all the answers

    What does the term 'scatter incidents' refer to in nuclear medicine imaging?

    <p>Detection of non-annihilation photons</p> Signup and view all the answers

    What type of gas filled administration requires a negative pressure room?

    <p>$Xe$ administration</p> Signup and view all the answers

    'Dead time' in PET/CT imaging refers to:

    <p>$Time period during which the detector cannot record another event$</p> Signup and view all the answers

    What uses a 2D projection to make a 3D image in nuclear medicine imaging?

    <p>Single Photon Emission Computed Tomography (SPECT)</p> Signup and view all the answers

    What happens to the annihilation photons if they are not determined to be in coincidence during a PET scan?

    <p>They are discarded</p> Signup and view all the answers

    What component is used in 2D PET imaging to absorb cross plane annihilation photons and improve image quality?

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

    Study Notes

    Coincidence Imaging

    • In coincidence imaging, the essential requirement for the detection of annihilation photons is that they are detected by both detectors on each side.
    • Annihilation photons not determined to be in coincidence during a PET scan are discarded.
    • The energy of the annihilation photons emitted from positron-emitting radionuclides is 511 keV.
    • The role of the Pulse Height Analyzer is to identify the annihilation photons in coincidence imaging.

    Radionuclides

    • Thallium-201 is not cyclotron produced and is used for Myocardial perfusion imaging.

    PET Imaging

    • The chief benefit of time-of-flight (TOF) technology is improved image resolution.
    • The consequence of dead time is reduced image quality.
    • The main limitation of annihilation photon imaging in PET is scatter incidents.
    • Attenuation corrected images look very different from non-attenuation corrected images.

    CT Imaging

    • The primary purpose of the filter in an x-ray tube is to remove low-energy x-rays.
    • The concept of helical scanning involves the table moving through the gantry as the gantry rotates around the table.
    • The filter selectively removes low-energy x-rays.
    • The range of units of attenuation in a CT study is -1000 to +1000, expressed relative to the attenuation of water.
    • Air has a range of attenuation units from -900 to -1000.
    • CT employs x-rays to create cross-sectional images of the body.
    • The approximate CT number ranges for air, soft tissue, and bone are -1000, 0-100, and 1000-3000, respectively.

    MRI Imaging

    • MRI uses magnetic fields and radio waves to generate detailed images of internal structures.
    • The main advantage of MRI over CT is its ability to provide detailed images without ionizing radiation.

    Gas Administration

    • Xenon gas administration requires a negative pressure room.
    • The washout phase of gas administration involves absorbing the Xenon gas using charcoal.
    • Oxygen is used to make the liquid DTPA a breathable aerosol.

    Other

    • The term 'scatter incidents' refers to the scattering of gamma rays by surrounding tissue.
    • The purpose of shimming coils is to correct for magnetic field inhomogeneities.
    • The function of RF coils is to transmit and receive radio signals.
    • The ability of an imaging system to detect and accurately measure gamma rays is referred to as sensitivity.
    • Pitch change in CT imaging affects the amount of radiation a patient is exposed to.
    • 2D PET imaging uses a 2D projection to make a 3D image.
    • The main reason for attenuation being more of a problem in PET than in SPECT is the longer distance traveled by the annihilation photons.
    • The purpose of time of flight (TOF) technology is to improve image resolution.
    • The delayed coincidence sinogram method is used to correct for randoms in PET imaging.
    • The main purpose of a sinogram is to evaluate motion in PET imaging.

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    Description

    Test your knowledge of positron emission tomography (PET) iterative reconstruction, noise, dead time, and attenuation. Learn about the consequences of dead time and the impact of attenuation on image quality.

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