PET Image Characteristics and Reconstruction
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Questions and Answers

Which factor contributes to the decrease in sensitivity due to small active area receiving annihilation photons in PET?

  • Impact of ring geometry
  • Decreased count rate
  • Limited availability of annihilation photons (correct)
  • Increased noise equivalent count rate
  • What is the chief benefit of time-of-flight (TOF) technology in PET?

  • Improved spatial resolution (correct)
  • Increased count rate
  • Limiting the location of the annihilation to a small part of the LOR
  • Reduced scatter fraction
  • What does a standardized uptake value (SUV) of 1 indicate?

  • Low sensitivity due to small active area
  • Completely even biodistribution (correct)
  • Inherent limitations of annihilation photon imaging
  • High noise equivalent count rate (NECR)
  • How does time-of-flight (TOF) technology improve PET image quality?

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

    What is the primary quantitative expression for count rate in PET?

    <p>Noise equivalent count rate (NECR)</p> Signup and view all the answers

    What contributes to the variation in sensitivity and spatial resolution in the axial direction in 3D PET acquisition mode?

    <p>Variable density of lines of response (LORs)</p> Signup and view all the answers

    What does a standardized uptake value (SUV) greater than 1 indicate in PET imaging?

    <p>An area of increased activity</p> Signup and view all the answers

    Which characteristic of PET images results not only from the inherent variability of radioactive decay and the reconstruction process, but also from random and scatter count rates and attenuation effects?

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

    Why is iterative reconstruction favored for PET images?

    <p>To deal with noise</p> Signup and view all the answers

    What is the largest contributor to dead time in PET imaging?

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

    What is the consequence of dead time in PET imaging?

    <p>Mispositioning of events</p> Signup and view all the answers

    Which characteristic of PET images can vary from 3 to 6 in the head and can be as high as 100 in the torso?

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

    What must be subtracted before attenuation correction is done in PET imaging to represent the radiopharmaceutical distribution correctly?

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

    What effect causes counts from a small volume to be spread out over a larger volume in the reconstructed image?

    <p>Partial volume effect</p> Signup and view all the answers

    What is the primary reason for using singles events to verify lack of coincidence in PET imaging?

    <p>To verify dead time</p> Signup and view all the answers

    What is the benefit of using three or more annihilation photons detected within the coincidence timing window in PET imaging?

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

    What is the primary consequence of not correcting for attenuation in PET imaging?

    <p>Mispositioning of events</p> Signup and view all the answers

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