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GAMMA CAMERA-PULSE HEIGHT SPECTRUM

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GAMMA CAMERA-PULSE HEIGHT SPECTRUM

1. γ rays are scattered within the patient - scattered γ rays have less energy.
2. γ rays may lose energy through Compton interactions in the crystal before eventually escaping. These rays will produce pulses of reduced height.
3. The photopeak corresponds to γ rays that have come from the patient and have not suffered Compton scattering.
4. Due to transmission and detection factors, the peak has a measurable width expressed as the full width at half maximum (FWHM).
5. The Compton tail on the left of the spectrum represents pulses of a lower energy - only pulses in the photopeak are useful.
6. A pulse height analyser (PHA) is used to reject those within the Compton tail - lets through pulses whose energy lies ± 10% of the photopeak.


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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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