What is the purpose of the pulse height analyzer (PHA) in a gamma camera?

What is the purpose of the pulse height

Multiple choice — select the best answer

AAmplify PMT pulses before position calculation
BEliminate afterglow in the NaI crystal
CControl the high voltage applied to PMTs
DAccept only pulses within a set energy window to reject scatter

✓ Correct answer: D. Accept only pulses within a set energy window to reject scatter The PHA discriminates between pulses based on their amplitude (proportional to photon energy). By setting a window around the photopeak (e.g., ±10% of 140 keV), scatter photons with lower energy are rejected, improving image contrast.

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What is the purpose of the pulse height analyzer (PHA) in a gamma camera?

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