Photon counting CT apparatus

Patent metadata

Field	Value
Publication number	US-9693743-B2
Application number	US-201514722689-A
Country	US
Kind code	B2
Filing date	May 27, 2015
Priority date	May 28, 2014
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

According to on embodiment, a photon counting CT apparatus includes a hybrid detector and processing circuitry. The hybrid detector includes CT detectors and PCCT detectors. The CT detectors output integral signals concerning the detected X-rays. The PCCT detectors output a count signal for each of a plurality of energy bands concerning the detected X-rays. The processing circuitry estimate a count signal concerning an estimation target CT detector of the CT detectors based on an integral signal output from the estimation target CT detector and a count signal output from the PCCT detector. And the processing circuitry reconstruct an image based on the estimated count signal and the count signal.

First claim

The invention claimed is:

1. A photon counting CT apparatus comprising:
an X-ray source configured to generate X-rays;
a hybrid detector including a plurality of integral type detectors and a plurality of photon counting type detectors, which detect X-rays generated from the X-ray source and are two dimensionally tiled on a detector array surface of the hybrid detector, the plurality of integral type detectors outputting integral signals concerning the detected X-rays, and the plurality of photon counting type detectors outputting a count signal for each of a plurality of energy bands concerning the detected X-rays; and
a processing circuitry configured to
estimate a count signal by a particular estimation target integral type detector of the plurality of integral type detectors based on an integral signal output from the particular estimation target integral type detector and a count signal output from the photon counting type detectors arranged around the particular estimation target integral type detector on the detector array surface; and
reconstruct a photon counting type image based on the estimated count signal and the count signal.

2. The apparatus of claim 1 , wherein the plurality of integral type detectors and the plurality of photon counting type detectors are arranged near each other.

3. The apparatus of claim 1 , wherein the estimation target integral type detector is spatially close to the one of the plurality of photon counting type detectors.

4. The apparatus of claim 3 , wherein the processing circuitry interpolates the count signal concerning the estimation target integral type detector based on the count signal output from the one of the plurality of photon counting type detectors close to the estimation target integral type detector and normalizes the interpolated count signal by using the integral signal output from the estimation target integral type detector.

5. The apparatus of claim 4 , wherein the processing circuitry normalizes the interpolated count signal by using the integral signal output from the estimation target integral type detector and a normalization parameter based on a calibration count signal output from the one of the plurality of photon counting type detectors and a calibration integral signal output from the estimation target integral type detector during a calibration scanning in advance of an estimation of the count signal.

6. The apparatus of claim 5 , wherein the processing circuitry calculates the normalization parameter based on the calibration count signal output from the one of the plurality of photon counting type detectors and the calibration integral signal output from the estimation target integral type detector during the calibration scanning.

7. The apparatus of claim 6 , wherein the calibration scanning is performed for each of a plurality of tube voltages, and
the processing circuitry calculates the normalization parameter at each of the plurality of tube voltages.

8. The apparatus of claim 1 , wherein the processing circuitry
estimates an integral signal concerning an estimation target photon counting type detector of the plurality of photon counting type detectors, when a reconstruction of an integral type image is instructed, based on a normalization parameter based on a calibration count signal output from the estimation target photon counting type detector and a calibration integral signal output from one of the plurality of integral type detectors close to the estimation target photon counting type detector during a calibration scanning in advance of an estimation of the integral signal and the count signal output from the estimation target photon counting type detector.

9. The apparatus of claim 8 , wherein the processing circuitry calculates the estimated integral signal by normalizing the count signal output from the estimation target photon counting type detector by using the normalization parameter.

10. The apparatus of claim 8 , wherein the processing circuitry reconstructs the integral type image based on the estimated integral signal and the integral signal when the reconstruction of the integral type image is instructed.

11. The apparatus of claim 8 , wherein the processing circuitry calculates the normalization parameter based on the calibration count signal output from the estimation target photon counting type detector and the calibration integral signal output from the one of the plurality of integral type detectors during the calibration scanning.

12. The apparatus of claim 11 , wherein the calibration scanning is performed for each of a plurality of tube voltages, and
the processing circuitry calculates the normalization parameter at each of the plurality of tube voltages.

13. A photon counting CT apparatus comprising:
an X-ray source configured to generate X-rays;
a hybrid detector including a plurality of integral type detectors and a plurality of photon counting type detectors, which detect X-rays generated from the X-ray source and are two dimensionally tiled on a detector array surface of the hybrid detector, the plurality of photon counting type detectors outputting a count signal for each of a plurality of energy bands concerning an X-ray spectrum, and the plurality of integral type detectors outputting integral signals throughout the X-ray spectrum;
a processing circuitry configured to
estimate an integral signal of a particular estimation target photon counting type detector of the plurality of photon counting type detectors based on a normalization parameter based on a calibration count signal output from the particular estimation target photon counting type detector and a calibration integral signal output from one of the plurality of integral type detectors during a calibration scanning in advance of an estimation of the integral signal, and a count signal output from the particular estimation target photon counting type detector; and
reconstruct an image based on the estimated integral signal and the integral signal.

Assignees

• Toshiba Medical Sys Corp

Inventors

• Arakita Kazumasa
• Ozaki Masahiro

Classifications

• G06T12/10

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• G01T1/1606

  with other specified detectors not provided for in the other subgroups of G01T1/16 · CPC title

• G01N23/046 Primary

  using tomography, e.g. computed tomography [CT] · CPC title

• G01T1/2018

  Scintillation-photodiode combinations · CPC title

• G01N2223/50

  Detectors · CPC title