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PET-COINCIDENCE DETECTION

Physics

PET-COINCIDENCE DETECTION

1. A coincidence occurs when two γ rays are detected along a straight line (line of response, LOR) within a very narrow time frame (~1ns).

TYPES OF COINCIDENCES
2. True coincidence (line a) - the simultaneous detection of two unscattered photons from a single annihilation.

3. Scatter (line b) - one or both photons are Compton scattered in the patient and both are detected. Solution: Energy discrimination. However the photopeak window is wide due to poor energy resolution of the scintillators so scatter coincidence not eliminated.

4. Random (line c) - photons from different annihilations happen to be detected simultaneously.


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REFERENCES

1. Bushberg, J. T. (2012). The essential physics of medical imaging. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Find it at Amazon
2. Heggie, J. C., Liddell, N. A., & Maher, K. P. (1997). Applied imaging technology. Melbourne: St. Vincents Hospital.

Ⓒ A. Manickam 2018

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