Percent energy resolution is defined as what calculation?

Percent energy resolution is a measure used in nuclear medicine to quantify how well a detector can distinguish between different energy levels of radiation. It is particularly significant in evaluating the performance of gamma cameras and other nuclear imaging equipment.

The correct calculation for percent energy resolution involves determining the Full Width at Half Maximum (FWHM) of the photo peak in relation to the energy of that peak. Specifically, percent energy resolution is defined as the FWHM divided by the photo peak energy, expressed as a percentage. This helps to normalize the resolution relative to the energy of the gamma rays being measured, making it a useful metric to compare the performance of different detectors regardless of the specific energy.

By using the formula:

[ \text{Percent Energy Resolution} = \left( \frac{\text{FWHM}}{\text{Photo Peak Energy (keV)}} \right) \times 100 ]

the resulting value reflects how much uncertainty there is in determining the energy of the detected photons. A smaller value indicates a better resolution, meaning the detector can more accurately identify the energy of incoming photons.

This understanding emphasizes that option D provides the correct approach to calculating percent energy resolution in a manner that reflects both the FWHM and the photo peak energy,