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EP-3684257-B1 - SYSTEM AND METHOD FOR LOW-DOSE MULTI-SPECTRAL X-RAY TOMOGRAPHY

EP3684257B1EP 3684257 B1EP3684257 B1EP 3684257B1EP-3684257-B1

Inventors

  • PAN, XIAOCHUAN
  • CHEN, Buxin
  • ZHANG, ZHENG
  • SIDKY, EMIL
  • XIA, DAN

Dates

Publication Date
20260506
Application Date
20180921

Claims (15)

  1. A multi-spectral tomography imaging system (2600) comprising: one or more source devices (2612) configured to direct beams of radiation in multiple spectra to a region of interest (ROI); one or more detectors (2622) configured to receive at least a portion of the beams of radiation; and a processor (2604) in communication with the one or more source devices (2612) and the one or more detectors (2622), wherein the processor (2604) is configured to: cause movement in at least one of the one or more source devices (2612), the one or more detectors (2622), and the ROI such that a first beam of radiation with a first spectrum is directed to the ROI for less than 360 degrees of movement of the ROI relative to the one or more source devices (2612) and the one or more detectors (2622); process data detected by the one or more detectors (2622), wherein the data results at least in part from the first beam of radiation with the first spectrum that is directed to the ROI for less than the 360 degrees of movement of the ROI, and wherein, to process the data, the processor (2604) is configured to implement a one-step inversion approach which includes: accessing a non-linear data model; accessing a non-convex optimisation program which is based on the non-linear data model; using an algorithm for numerically solving the non-convex optimization program to satisfy convergence conditions on the data; and wherein the processor (2604) is further configured to generate an image of the ROI based on the processed data.
  2. The multi-spectral tomography imaging system of claim 1, wherein the beams of radiation in multiple spectra comprise the first beam of radiation at the first spectrum and a second beam of radiation at a second spectrum such that the system performs dual-energy X-ray tomography or dual-energy computed tomography.
  3. The multi-spectral tomography imaging system of claim 2, wherein the processor is configured to control the one or more source devices such that the one or more source devices direct the first beam of radiation and the second beam of radiation at the ROI each for less than 2π of the movement of the ROI relative to the one or more source devices and the one or more detectors.
  4. The multi-spectral tomography imaging system of claim 1, wherein the one or more source devices comprise a single source device, wherein the single source device comprises a radiation source and a switch configured to switch the radiation source between a first spectrum and a second spectrum, wherein the processor is configured to control the radiation source and the switch so that the single source device outputs radiation in the first spectrum during a first relative movement of the ROI with respect to the single source device and the one or more detectors, and outputs radiation in the second spectrum during a second relative movement of the ROI with respect to the single source device and the one or more detectors, and wherein the first relative movement and the second relative movement are less than 360 degrees.
  5. The multi-spectral tomography imaging system of claim 4, wherein the processor is configured to control the radiation source and the switch such that the single source device outputs radiation continuously at the first spectrum during the first relative movement of the ROI.
  6. The multi-spectral tomography imaging system of claim 5, wherein the processor is configured to control the radiation source and the switch such that the single source device outputs radiation continuously at the second spectrum during the second relative movement of the ROI.
  7. The multi-spectral tomography imaging system of claim 4, wherein the first relative movement of the ROI with respect to the single source device and the one or more detectors is at a first angle.
  8. The multi-spectral tomography imaging system of claim 7, wherein the second relative movement of the ROI with respect to the single source device and the one or more detectors is at a second angle, and wherein a sum of the first angle and the second angle is 360 degrees or less.
  9. The multi-spectral tomography imaging system of claim 8, wherein the single source device is configured to: output at the first spectrum continuously for the first angle; and output at the second spectrum discontinuously for the second angle.
  10. The multi-spectral tomography imaging system of claim 8, wherein the single source device is configured to output at the first spectrum discontinuously for the first angle and output at the second spectrum discontinuously for the second angle.
  11. The multi-spectral tomography imaging system of claim 10, wherein the first angle is a sum of rotation segments of relative movement during which the single source device outputs at the first spectrum.
  12. The multi-spectral tomography imaging system of claim 1, wherein the one or more sources comprise a single source device that directs a first beam of radiation through a filter to form a first spectrum and that directs a second beam of radiation that does not go through the filter to form a second spectrum.
  13. A method of performing multi-spectral tomography using a multi-spectral tomography imaging system (2600), the method comprising: directing, by one or more source devices (2612), beams of radiation in multiple spectra to a region of interest (ROI); receiving, by one or more detectors (2622), at least a portion of the beams of radiation; causing, by a processor (2604) in communication with the one or more source devices (2612) and the one or more detectors (2622), movement in at least one of the one or more source devices (2612), the one or more detectors (2622), and the ROI; processing, by the processor (2604), data detected by the one or more detectors (2622) by solving an optimization problem based on the data, wherein the data results at least in part from a first beam of radiation with a first spectrum that is directed to the ROI, and wherein processing the data includes a one-step inversion approach which includes: accessing a non-linear data model; accessing a non-convex optimisation program which is based on the non-linear data model; using an algorithm for numerically solving the non-convex optimization program to satisfy convergence conditions on the data; and wherein the processing further includes generating an image of the ROI based on the processed data.
  14. The method of claim 13, wherein processing the data includes performing a transformation on the non-linear data model associated with the data.
  15. The method of claim 14, further comprising solving the optimization problem based at least in part on the transformation on the non-linear data model.

Description

BACKGROUND X-ray tomography, including computed tomography (CT), may be used for a variety of purposes, such as for screening, diagnosis, evaluation of diseases, analysis of materials, etc. In the screening, diagnosis, and evaluation cases, the X-ray tomographic images, including CT images, can measure quantities related to X-ray attenuation values at different X-ray energies in the imaged subject, such as a patient. One way to acquire additional information using X-rays is to measure the patient at multiple different energies, since the attenuation of all materials is energy dependent. This energy dependence is different for different materials. In dual-energy X-ray tomography, including dual-energy CT imaging, the subject is illuminated with two different X-ray spectra corresponding to two different energy distributions. In the medical X-ray imaging energy range, there are typically two dominant physical effects, i.e., the Compton and photoelectric effects. US 2017/086775 (Madhav et al.) discloses systems and methods for dual-energy computed tomography imaging. DE 10 2007 053390 (Siemens AG) relates to a method of producing a temporal sequence of tomographic images. WO 2012/009725 (Mayo Foundation) discloses a method for creating an energy series of images acquired using a multi- energy computed tomography (CT) imaging system. WO 2005/009206 (Besson) relates to a dynamic multi-spectral X-ray imaging system. SUMMARY The invention provides a multi-spectral tomography imaging system in accordance with claim 1. The invention also provides a method of performing multi-spectral tomography in accordance with claim 13. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various aspects of the subject matter and together with the description, serve to explain its principles. Wherever convenient, the same reference numbers will be used throughout the drawings to refer to the same or like elements. Fig. 1A depicts a single-kVp switch imaging technique in which there is one rotation for the low kVp and another rotation for the high kVp in accordance with an illustrative embodiment.Fig. 1B is a graph showing multiple normalized spectral including 80kVp (120), 100 kVp (125), 120 kVp (130), and 140 kVp (135) in accordance with an illustrative embodiment.Fig. 2 illustrates an example of a sparse-view configuration in which multi-spectral data are collected at multi sets of interlaced sparse views over an angular range of any value between 180 degrees and 360 degrees in accordance with an illustrative embodiment.Fig. 3 illustrates a limited-angular-range configuration in which multi-spectral data are collected at multiple sets of limited-angular ranges over an angular range of any value between 180 degrees to 360 degrees in accordance with an illustrative embodiment.FIG. 4 illustrates a block configuration in which multi-spectral data are collected at multiple sets of detector blocks over an angular range of any value 2π or less in accordance with an illustrative embodiment.FIG. 5 is a representation of a sparse-view configuration in which low-kVp and high-kVp data are collected at two sets of interlaced sparse views uniformly distributed over 2π in accordance with an illustrative embodiment.FIG. 6 is a representation of a limited-angular-range configuration 600 in which low-kVp and high-kVp data (from a source outputting low-kVp 602 and outputting high-kVp 604 onto object 306) are collected over the two adjacent limited-angular ranges in accordance with an illustrative embodiment.FIG. 7 is a representation of a split-illumination configuration in which low-kVp and high-kVp data are collected with two adjacent illumination coverage of low-kVp and high-kVp at each of 640 views uniformly distributed over 2π in accordance with an illustrative embodiment.FIG. 8 is a representation of a block-illumination configuration in which low-kVp and high-kVp data are collected with multiple adjacent alternating illumination coverage of low-kVp and high-kVp at each of 640 views uniformly distributed over 2π in accordance with an illustrative embodiment.FIG. 9 is a table summarizing the materials used in the composition of the phantoms of Fig. 10 in accordance with an illustrative embodiment.FIG. 10A depicts a DE-472 phantom with 18 regions of interest within 16 circular inserts and 2 background areas highlighted by 1 to 18 in accordance with an illustrative embodiment.FIG. 10B is a lung phantom in accordance with an illustrative embodiment.FIG. 10C is a lung phantom with a muscle region of interest in accordance with an illustrative embodiment.FIG. 10D is a lung phantom with a bone region of interest in accordance with an illustrative embodiment.FIG. 10E is a lung phantom with a water region of interest in accordance with an illustrative embodiment.FIG. 11 illustrates convergence metrics D(b(n)), ΔΨ(b(n)), and cα(b (n)), and reconstruction-error Δb