Nyquist frequency in detector sampling: which statement is correct?

Nyquist frequency in detector sampling: which statement is correct?

• A. It defines the maximum representable spatial frequency.
• B. It determines the display brightness of the monitor.
• C. It is unrelated to sampling.
• D. It depends on patient dose.

Answer: (A)

Nyquist frequency is set by how often you sample the image: it is half of the detector’s sampling rate. In imaging, sampling comes from the detector’s pixel spacing, so smaller pixels mean a higher sampling rate and a higher Nyquist limit. This limit marks the highest spatial frequency that can be represented without aliasing; any detail finer than Nyquist cannot be stored accurately and will fold back into the image as artifacts. That’s why the statement that Nyquist frequency defines the maximum representable spatial frequency is the correct one. Display brightness and patient dose aren’t determined by the sampling rate in this sense. Brightness relates to the display device and exposure settings, while dose concerns exposure, not the sampling geometry. So those options don’t fit because Nyquist is all about how often you sample and the resulting limit on resolvable detail.

Nyquist frequency is set by how often you sample the image: it is half of the detector’s sampling rate. In imaging, sampling comes from the detector’s pixel spacing, so smaller pixels mean a higher sampling rate and a higher Nyquist limit. This limit marks the highest spatial frequency that can be represented without aliasing; any detail finer than Nyquist cannot be stored accurately and will fold back into the image as artifacts. That’s why the statement that Nyquist frequency defines the maximum representable spatial frequency is the correct one.

Display brightness and patient dose aren’t determined by the sampling rate in this sense. Brightness relates to the display device and exposure settings, while dose concerns exposure, not the sampling geometry. So those options don’t fit because Nyquist is all about how often you sample and the resulting limit on resolvable detail.