US 5,331,682 A · Radiation detector offset and afterglow compensation technique

Abstract

A computed tomography imaging system includes a source of radiation and a detector that produces an output signal representing sensed radiation from the source. Prior to using the system to produce an image, the source produces a pulse of radiation and the detector output signal is periodically sampled until the output signal has decayed to a negligible level. These samples form values which define a standard response of the detector. Thereafter when image samples are acquired, a decaying output signal from detector is sampled after radiation production terminates. The decay samples are compared to the standard response and coefficients defining the comparison are found. The coefficients and the standard response data are used to derive compensation values which are arithmetically applied to the image samples thereby producing compensated samples. An image is reconstructed from the compensated samples.

Claims10

Dependent claims

A medical imaging system comprising:

a source of radiation:
a detector for sensing radiation from said source and producing an output signal representing the sensed radiation, said detector having a radiation response which decay with time, the output signal being affected by an offset which varies temporally;
a first means for storing a set of values X.sub.i (t) defining a standard response for the detector;
means for acquiring samples of the output signal periodically from said detector;
means for receiving a plurality of samples of the output signal that said means for acquiring produced after extinction of radiation;
means for fitting the plurality of samples to the set of values defining the standard response and deriving coefficients defining a degree of fit;
means for determining, for a given sample, a compensation value derived from the values defining the standard response of the detector to radiation and from the coefficients defining a degree of it;
means for arithmetically combining the compensation value and the given sample to produce a compensated sample;
and
means for reconstructing an image from compensated samples.

7 more elements

Dependencies are inferred from the claim text.

Radiation detector offset and afterglow compensation technique

Life of this patent

Radiation detector offset and afterglow compensation technique

Life of this patent

Abstract

Claims10