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 (B)</p> Signup and view all the answers

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

<p>Identifying the annihilation photons (B)</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 (C)</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 (D)</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) (C)</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 (C)</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 (D)</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 (C)</p> Signup and view all the answers

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

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

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

<p>Resolution variation with radionuclide used (D)</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 (A)</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 (C)</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 (D)</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 (B)</p> Signup and view all the answers

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

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

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

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

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

<p>Nebulizer (A)</p> Signup and view all the answers

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

<p>Charcoal (A)</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 (A)</p> Signup and view all the answers

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

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

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

<p>X-rays (D)</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 (A)</p> Signup and view all the answers

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

<p>Single events (A)</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 (B)</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 (A)</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 (C)</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 (B)</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 (B)</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; (D)</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 (A)</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 (C)</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 (B)</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 (D)</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 (B)</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 (B)</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 (D)</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' (C)</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 (A)</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 (A)</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 (B)</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 (B)</p> Signup and view all the answers

What distinguishes PET as more quantitative than SPECT?

<p>PET allows measurement of physiologic quantities in vivo (D)</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 (A)</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 (B)</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 (D)</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 (D)</p> Signup and view all the answers

What distinguishes PET as more quantitative than SPECT?

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

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

<p>Attenuation correction errors (D)</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 (D)</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 (A)</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 (B)</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 (D)</p> Signup and view all the answers

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

<p>Xenon gas administration (A)</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 (D)</p> Signup and view all the answers

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

<p>Pulse Height Analyzer (A)</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 (B)</p> Signup and view all the answers

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

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

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

<p>$511 keV$ (A)</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 (C)</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 (C)</p> Signup and view all the answers

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

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

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

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

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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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