2022 AAPM 64th Annual Meeting
Back to session list

Session Title: Attenuation Correction in PET and SPECT with and without Transmission Imaging
Question 1: Which one of the following is true regarding attenuation correction in PET and SPECT?
Reference:Reference: S.R. Cherry, J.A. Sorenson, and M.E. Phelps. Physics in Nuclear Medicine 4th edition, Elsevier, 2012, pp 279-343.
Choice A:The impact of attenuation on the reconstruction of a uniform distribution of gamma-ray emitting imaging agent in a cylindrical tub phantom will be seen as decreased estimated activity most strongly at the edges, and least in the center of the distribution.
Choice B:The correction of attenuation in SPECT is easier to perform than in PET, as in SPECT one only must account for the attenuation of individual photons from where they are emitted to the edge of the attenuating medium.
Choice C:The uncorrected inclusion of scattered photons in the photopeak projections acquired in SPECT has an impact upon the accuracy of activity quantitation obtained even with attenuation correction.
Choice D:Attenuation correction is generally less needed in PET than SPECT as the 511 keV photons imaged in PET are higher in energy than the photons typically imaged in SPECT.
Question 2: Which of the following is false when comparing transmission imaging and CT based estimation of attenuation maps?
Reference:S.R. Cherry, J.A. Sorenson, and M.E. Phelps. Physics in Nuclear Medicine 4th edition, Elsevier, 2012, pp 279-343.
Choice A:An advantage of CT estimation is that it generally employs much fewer photons, thus the estimated attenuation map has more noise.
Choice B:In PET the polychromatic beam of photons used in CT require a more complicated correction of the estimated attenuation map for correcting the attenuation of the 511 keV photons used in imaging, than maps estimated from transmission imaging of high energy photons from radionuclides.
Choice C:An advantage of CT is that when not in use CT systems do not emit ionizing radiation; whereas the radionuclide sources used in transmission imaging must shielded when not in use.
Choice D:The radiation dose delivered to the patient in transmission imaging is generally less than that from CT.
Question 3: Which one is not a cause of mis-registration between CT and PET images in PET/CT imaging of the thorax and abdomen?
Reference:Pan T, Mawlawi O, Nehmeh SA, Erdi YE, Luo D, Liu HH, Castillo R, Mohan R, Liao Z, Macapinlac HA. Attenuation correction of PET images with respiration-averaged CT images in PET/CT. J Nuc Med 46(9):1481-1487, 2005.
Choice A:Patient free breathing during PET/CT imaging
Choice B:Breathing-inducted tumor motion during PET/CT imaging
Choice C:Mismatch of the spatial resolutions of CT and PET
Choice D:Mismatch of the temporal resolutions of CT and PET
Question 4: Which one is not a potential pitfall of deep learning-based CT-less attenuation correction in clinical perspective?
Reference:Yang, Jaewon, et al. "CT-less direct correction of attenuation and scatter in the image space using deep learning for whole-body FDG PET: potential benefits and pitfalls." Radiology: Artificial Intelligence 3.2 (2020): e200137.
Choice A:False negative due to blurring
Choice B:False positive due to pseudo patterns
Choice C:Mismatched correction
Choice D:Over/under-correction
Question 5: Which one is not a benefit of deep learning-based attenuation correction (DL-AC) as post processing in the image space?
Reference:Yang, Jaewon, et al. "Direct attenuation correction using deep learning for cardiac SPECT: a feasibility study." Journal of Nuclear Medicine 62.11 (2021): 1645-1652.
Choice A:Pseudo CT generation is not needed.
Choice B:Processing is fast, almost real-time.
Choice C:Joint correction of attenuation and scatter is feasible.
Choice D:Physics-driven deep learning is feasible.
Question 6: Which one of the following is NOT true regarding AI based indirect attenuation correction methods in SPECT?
Reference:Chen, X.,et al. Direct and indirect strategies of deep-learning-based attenuation correction for general purpose and dedicated cardiac SPECT. Eur J Nucl Med Mol Imaging 2022, PMID: 35169887, DOI: 10.1007/s00259-022-05718-8
Choice A:Indirect attenuation correction is slower than the direct attenuation correction.
Choice B:There are less artifacts in the direct methods.
Choice C:An attenuation map is generated in the indirect methods.
Choice D:Reconstruction based attenuation correction is needed for the indirect methods.
Back to session list