calculation of normalization factors and their storage are carried out by the
manufacturer’s menu-driven software.
Questions
- Describe the principles of positron emission tomography.
- How is the attenuation of annihilation photons corrected for in
PET? - Attenuation of photons is directly proportional to the thickness and
density of the material through which they pass and inversely propor-
tional to photon energy. True or False? - How do random and scatter radiations affect PET images? What are
the methods for correcting these effects? - What are the typical values of spatial resolutions of PET scanners?
- What is the cause of the partial-volume effect and how would you
rectify it? - What are the most common radionuclides used in PET?
- Explain why^13 N-ammonia gives better spatial resolution than^82 Rb in
the PET imaging of myocardium. - What are the factors that affect the spatial resolution of a PET scanner?
- What are the initial steps that are taken in the reconstruction of 3-D
data? - The overall sensitivity in 3-D acquisition is four to eight times higher
than in 2-D acquisition. Why? - What is the daily quality control test for a PET scanner?
- The sensitivity of a PET scanner increases with the size of the detec-
tor. True or False? - Explain why LSO detectors are preferred to BGO detectors.
- Transverse resolution is worse at the center of the field of view than
away from the center. True or False?
References and Suggested Readings
Bacharach SL. Image analysis. In: Wagner HN Jr, Szabo Z, Buchanan JW, eds.
Principles of Nuclear Medicine. Philadelphia: W. B. Saunders; 1995:393–404.
Budinger TF. PET instrumentation: what are the limits? Semin Nucl Med.1998;
28:247.
Cherry SR, Dahlbom M. PET: Physics, instrumentation, and scanners. In: Phelps
ME.PET: Molecular Imaging and Its Biological Applications. New York; Springer:
2004.
Cherry SR, Sorensen JA, Phelps ME.Physics in Nuclear Medicine. 3rd ed. Philadel-
phia; W. B. Saunders: 2003.
Hoffman EJ, Phelps ME. Positron emission tomography: Principles and quantita-
tion. In: Phelps ME, Mazziotta J, Schelbert H, eds.Positron Emission Tomogra-
206 13. Positron Emission Tomography