Combined X-ray and nuclear imaging

Patent metadata

Field	Value
Publication number	US-10448909-B2
Application number	US-201716082986-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Mar 8, 2016
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

The invention relates to a combined imaging detector (110) for the detection of x-ray and gamma quanta. The combined imaging detector (110) is adapted for simultaneous detection of gamma and x-ray quanta. The combined imaging detector (110) includes an x-ray anti-scatter grid (111), a layer of x-ray scintillator elements (112), a first photodetector array (113), a layer of gamma scintillator elements (114), and a second photodetector array (115) that are arranged in a stacked configuration along a radiation-receiving direction (116). The x-ray anti-scatter grid (111) comprises a plurality of septa (117A, B, C) that define a plurality of apertures (118) which are configured to collimate both x-ray quanta and gamma quanta received from the radiation receiving direction (116) such that received gamma quanta are collimated only by the x-ray anti-scatter grid (111). The use of the x-ray anti-scatter grid as a collimator for received gamma quanta results in a significantly lighter combined imaging detector.

First claim

The invention claimed is:

1. An imaging detector for detecting gamma quanta and x-ray quanta, comprising:
an x-ray anti-scatter grid;
a layer of x-ray scintillator elements configured to generate x-ray scintillation light signals in response to the x-ray quanta;
a first photodetector array configured to convert the x-ray scintillation light signals into a first group of electrical signals;
a layer of gamma scintillator elements configured to generate gamma scintillation light signals in response to the gamma quanta;
a second photodetector array configured to convert the gamma scintillation light signals into a second group of electrical signals;
wherein the x-ray anti-scatter grid, the layer of x-ray scintillator elements, the first photodetector array, the layer of gamma scintillator elements, and the second photodetector array are arranged in a predetermined stacked configuration along a radiation receiving direction; wherein the x-ray anti-scatter grid comprises a plurality of septa that define a plurality of apertures which are configured to collimate the x-ray quanta and the gamma quanta received from the radiation receiving direction, such that the gamma quanta are collimated by the x-ray anti-scatter grid only; and
a reconstruction unit configured to generate a reconstructed nuclear scintigraphy image from a measured nuclear scintigraphy image, which is based on the second group of electrical signals, by subtracting a reference pixel value from a pixel value in the measured nuclear scintigraphy image.

2. The imaging detector of claim 1 , wherein the plurality of septa comprises a first set of septa that extend along a first direction, and a second set of septa that extend along a second direction;
wherein the first set of septa and the second set of septa are arranged in a stacked configuration along the radiation receiving direction, such that the first direction and the second direction are mutually transverse.

3. The imaging detector of claim 1 , wherein each septum in the plurality of septa has a depth along the radiation receiving direction that is less than or equal to approximately 5 millimeters, and/or each septum in the plurality of septa has a thickness in a direction perpendicular to the radiation receiving direction that is less than or equal to approximately 100 microns.

4. The imaging detector of claim 1 ,
wherein the reconstruction unit is further configured to generate the reconstructed nuclear image based on a point spread function model that represents a distribution of the gamma scintillation light signals for each aperture of the x-ray anti-scatter grid.

5. The imaging detector of claim 4 , wherein the point spread function model includes, in a direction perpendicular to the radiation receiving direction, a central lobe portion and a non-zero portion beyond the central lobe portion; and wherein the reconstructed nuclear image is generated by subtracting the non-zero portion from the point spread function.

6. The imaging detector of claim 4 , wherein the reconstructed nuclear image is a SPECT image corresponding to a radiotracer distribution in a volume of interest, and wherein the reconstruction unit is further configured to generate the reconstructed nuclear image using an iterative reconstruction algorithm that includes:
estimating the radiotracer distribution in the volume of interest;
projecting the estimated radiotracer distribution onto the combined imaging detector to provide a projected estimated scintillation light distribution;
receiving, based on the second group of electrical signals, distribution of the measured scintillation light signals corresponding to the radiotracer distribution;
comparing the distribution of the measured scintillation light signals with the projected estimated scintillation light distribution; and
updating the estimated radiotracer distribution in the volume of interest based on the comparing;
wherein the point spread function model is applied when projecting the estimated radiotracer distribution.

7. The imaging detector of claim 1 , wherein the reconstructed nuclear scintigraphy image corresponds to an object having a boundary; and
wherein the reference pixel value is at a point beyond the boundary in the measured nuclear scintigraphy image.

8. The imaging detector of claim 1 , further comprising a field of view for detected gamma quanta; wherein the reference pixel value is in the measured nuclear scintigraphy image at a point within approximately 10 pixels of a pixel at the edge of the field of view.

9. The imaging detector of claim 1 , wherein the subtracting is performed in the frequency domain.

10. A C-arm comprising the imaging detector of claim 1 .

11. A method for detecting gamma quanta and x-ray quanta, comprising:
providing an x-ray anti-scatter grid;
generating x-ray scintillation light signals by a layer of x-ray scintillator elements in response to the x-ray quanta;
converting the x-ray scintillation light signals by a first photodetector array into a first group of electrical signals;
generating gamma scintillation light signals by a layer of gamma scintillator elements in response to the gamma quanta;
converting the gamma scintillation light signals by a second photodetector array into a second group of electrical signals; wherein the x-ray anti-scatter grid, the layer of x-ray scintillator elements, the first photodetector array, the layer of gamma scintillator elements, and the second photodetector array are arranged in a predetermined stacked configuration along a radiation receiving direction; wherein the x-ray anti-scatter grid comprises a plurality of septa that define a plurality of apertures which are configured to collimate the x-ray quanta and the gamma quanta received from the radiation receiving direction, such that received gamma quanta are collimated by the x-ray anti-scatter grid only; and
generating a reconstructed nuclear scintigraphy image from a measured nuclear scintigraphy image, which is generated based on the second group of electrical signals, by subtracting a reference pixel value from a pixel value in the measured nuclear scintigraphy image.

12. A non-transitory computer-readable medium having one or more executable instructions stored thereon, which, when executed by a processor, cause the processor to perform a method for detecting gamma quanta and x-ray quanta, the method comprising:
providing an x-ray anti-scatter grid;
generating x-ray scintillation light signals by a layer of x-ray scintillator elements in response to the x-ray quanta;
converting the x-ray scintillation light signals by a first photodetector array into a first group of electrical signals;
generating gamma scintillation light signals by a layer of gamma scintillator elements in response to the gamma quanta;
converting the gamma scintillation light signals by a second photodetector array into a second group of electrical signals; wherein the x-ray anti-scatter grid, the layer of x-ray scintillator elements, the first photodetector array, the layer of gamma scintillator elements, and the second photodetector array are arranged in a predetermined stacked configuration along a radiation receiving direction; wherein the x-ray anti-scatter grid comprises a plurality of septa that define a plurality of apertures which are configured to collimate the x-ray quanta and the gamma quanta received from the radiation receiving direction, such that received gamma quanta are collimated by the x-ray anti-scatter grid only; and
generating a reconstructed nuclear scintigraphy image from a measured nuclear scintigraphy image, which is generated based on the second group of electrical signals,

Assignees

• Koninklijke Philips Nv

Inventors

• Wieczorek Herfried Karl
• Goedicke Andreas
• Alving Peter Lex

Classifications

• G06T12/00

  Tomographic reconstruction from projections · CPC title

• G01T1/1615

  using both transmission and emission sources simultaneously (SPECT imaging G01T1/1642; PET imaging G01T1/2985; detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects G01V5/20) · CPC title

• A61B6/5205

  involving processing of raw data to produce diagnostic data · CPC title

• A61B6/4233

  using matrix detectors · CPC title

• A61B6/4291

  the detector being combined with a grid or grating · CPC title