Method and apparatus for spectral computed tomography
AssigneeKoninklijke Philips Electronics N.V.
InventorRaz Carmi
Life of this patent
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Abstract
An apparatus receives signals generated by a detector (100) sensitive to ionizing radiation such as x-rays. A differentiator (204) generates an output indicative of the rate of change of the detector signal. A discriminator (206) classifies the amplitude of the differentiator (204) output. An integrator (208) triggered by the output of the discriminator (206) generates outputs indicative of the detected photons. One or more correctors (24a, 24b) corrects for pulse-pileups, and a combiner (25) uses the outputs of the correctors (24a, 24b) to generate an output signal indicative of the number and energy distribution of the detected photons.
Claims20
An apparatus comprising:
- a radiation sensitive detector which produces an output in response to ionizing radiation;
- a discriminator which produces first and second outputs based on the rate of change of the detector output;
- a first integrator triggered by the first discriminator output and which generates a first integrator output;
- a second integrator triggered by the second discriminator output and which generates a second integrator output;
- a first corrector which uses the first and second integrator outputs to generate a first output indicative of detected radiation having a first energy range and a second output indicative of detected radiation having a second energy range, wherein the first corrector corrects for pulse pile-ups in the detector output.
A method comprising:
- measuring a rate of change of an output signal produced by a radiation sensitive detector in response to an ionizing radiation photon;
- updating a first value if the rate of change is in a first range;
- updating a second value if the rate of change is in a second range;
- repeating the steps of measuring, updating the first value, and updating the second value for a plurality of photons;
- generating a first output indicative of photons detected in a first energy range, wherein the first output is a function of the first and second values;
- generating a second output indicative of photons detected in a second energy range, wherein the second output is a function of the first and second values.
A method comprising:
- estimating the energy of an ionizing radiation photon detected by a radiation sensitive detector;
- updating one of at least first and second values depending on the estimated energy;
- repeating the steps of estimating and updating for photons detected during a pre-selected time period;
- using the first and second values to generate a first output indicative of detected photons having a first range of energies and a second output indicative of detected photons having a second range of energies, wherein the first and second outputs include corrections for detector pulse pile ups.
Dependencies are inferred from the claim text.