Physics, Techniques and ProceduresAfterglow
the persistence in the light output from a
scintillation crystal in response to a pulse of radiation, for example
X-ray photons. In general, a low level light output persists or continues for a time longer than the duration of the
X-ray pulse. Afterglow is generally distinguished from the primary speed of the scintillator in that the primary speed is shorter and of higher amplitude than afterglow. The amplitude and duration of the afterglow depend on the scintillator used and is not a problem in some materials. The continued light output from afterglow, which appears as a slowly varying baseline, is undesirable when high accuracy is needed, and it can generate shading artefacts in
computed tomography CT images. If the afterglow is well characterized, mathematical algorithms can be used to reduce the error in measurements.
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