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EP-4308002-B1 - CONTACTLESS MEASUREMENT AND VISUALIZATION OF RESPIRATION FOR CHEST RADIOGRAPHY IMAGE EXAMINATIONS

EP4308002B1EP 4308002 B1EP4308002 B1EP 4308002B1EP-4308002-B1

Inventors

  • MENSER, BERND
  • SENEGAS, Julien, Thomas
  • JOCKEL, Sascha, Andreas
  • MENTRUP, DETLEF
  • SAALBACH, AXEL

Dates

Publication Date
20260506
Application Date
20220310

Claims (14)

  1. A breathing status determination device (10), comprising: - an input unit (12); - a processing unit (14); and - an output unit (16); wherein the input unit is configured to receive a sequence of depth images that is continuously captured with a sensor having a field of view covering a torso of a patient positioned for a chest radiography image examination; wherein the processing unit is configured to analyse the received sequence of depth images to determine a change of depth values inside at least one region-of-interest, ROI, over time that represents a motion of a patient anatomy orthogonal to an image plane of the sensor and/or a motion of a patient anatomy within an image plane of the sensor, and to determine a breathing signal based on the determined change of depth values inside the at least one ROI over time, wherein the processing unit is configured to determine a change of a mean depth value inside the at least one ROI to determine the breathing signal; and wherein the output unit is configured to provide the determined breathing signal,.
  2. Breathing status determination device according to claim 1, wherien the at least one ROI comprises at least two ROIs including a first ROI and a second ROI; wherien the processing unit is configured to determine a change of depth values inside the first ROI over time that represents a motion of a first patient anatomy orthogonal to the image plane and to determine a change of depth values inside the second ROI over time that represents motion of a second patient anatomy within the image plane; and wherien the processing unit is configured to determine a breathing signal based on the determined change of depth values inside both the first and the second ROIs.
  3. Breathing status determination device according to claim 1 or 2, wherein the at least one ROI comprises an ROI that covers the patient anatomy and a background on both sides of the patient.
  4. Breathing status determination device according to any one of the preceding claims, wherein when the patient is positioned in a lateral position for the chest radiography image examination, the at least one ROI comprise: - a first ROI comprising pixels representing the patient's back, and pixels representing an area in a background; - a second ROI comprising pixels representing the patient's chest, and pixels representing an area in a background; and - a third ROI on the patient's torso.
  5. Breathing status determination device according to any one of the preceding claims, wherein the at least one ROI comprises an ROI having pixels representing the patient's shoulder and pixels representing an area in a background.
  6. Breathing status determination device according to any one of the preceding claims, wherein the at least one ROI comprises an ROI covering the patient's torso and a background.
  7. Breathing status determination device according to any one of the preceding claims, wherein the processing unit is configured to determine the at least one ROI based on an active area of an automatic exposure control, AEC, dose measurement chambers or based on one or more anatomical landmarks of the patient.
  8. Breathing status determination device according to any one of the preceding claims, wherein the processing unit is further configured to determine a time point for releasing an x-ray exposure at a pre-defined breathing status based on the determined breathing signal.
  9. A chest radiography imaging system (100), comprising: - an x-ray imaging system (110) with an x-ray source (112) and an x-ray detector (114) spaced from the x-ray source to accommodate a patient to be imaged; - a sensor (120) having a field of view covering a torso of the patient positioned for the chest radiography image examination, wherein the sensor is configured to continuously capture a sequence of depth images of the patient's torso; and - a breathing status determination device (10) according to any one of the preceding claims.
  10. Chest radiography imaging system according to claim 9, further comprising: - a feedback device configured to receive a breathing signal from the breathing status determination device, and to provide feedback about a breathing status of the patient.
  11. Chest radiography imaging system according to claim 9 or 10, wherein the x-ray imaging system is configured to be manually controlled or automatically triggered for an image acquisition at a time point for releasing an x-ray exposure that is determined by the breathing status determination device.
  12. A method (200) for determining a breathing status of a patient in a chest radiography image examination, comprising: - receiving (210) a sequence of depth images that is continuously captured with a sensor having a field of view covering a torso of a patient positioned for the chest radiography image examination; - analysing (220) the received sequence of depth images to determine a change of depth values inside at least one region-of-interest, ROI, over time that represents a motion of a patient anatomy orthogonal to an image plane of the sensor and/or a motion of a patient anatomy within an image plane of the sensor, wherein a change of a mean depth value inside the at least one ROI is determined to determine the breathing signal; - determining (230) a breathing signal based on the determined change of depth values inside the at least one ROI over time; and - providing (240) the determined breathing signal.
  13. Method according to claim 12, further comprising: - determining a time point for releasing an x-ray exposure at a pre-defined breathing status based on the determined breathing signal.
  14. A computer program element for controlling a device according to any one of claims 1 to 8 or for controlling a system according to any one of claims 9 to 11, which when being executed by a processor is configured to carry out the method according to claim 12 or 13.

Description

FIELD OF THE INVENTION The present invention relates to chest radiography, and in particular to a breathing status determination device, to a chest radiography imaging system, to a method for determining a breathing status of a patient, and to a computer program element. BACKGROUND OF THE INVENTION Chest radiography is one of the most important and frequent diagnostic imaging examination. For acquiring a good radiographic image, certain diagnostic requirements and image quality criteria have been defined in international and national guidelines and recommendations. A chest radiography in postero-anterior (PA), antero-posterior (AP), or lateral (LAT) projection should be "performed at full inspiration and with suspended respiration". This is required for a proper visualization and assessment of relevant lung structures in the radiographic image. In today's workflow, the operator gives a breathing command, usually while leaving the examination room, and afterwards triggers the X-ray image acquisition without any visual feedback on the actual breathing state of the patient. Often enough, the patient does not fully comply with the breathing instructions, for example because the patient cannot understand the breathing command or because the patient is not able to hold his breath long enough. The latter may happen especially if the operator gives the breathing command while in the examination room and needs a few seconds to reach the X-ray release control. However, a radiography correctly taken at full inspiration facilitates the diagnostic task. Moreover, an image taken at a moment of strong respiratory or other chest motion may be degraded by motion blur. Document US2020202620A1 may be considered to disclose a breathing status determination device, comprising: an input unit; a processing unit; and an output unit; wherein the input unit is configured to receive a sequence of depth images that is continuously captured with a sensor having a field of view covering a torso of a patient positioned for a chest radiography image examination; wherein the processing unit is configured to analyse the received sequence of depth images to determine a change of depth values inside at least one region, over time that represents a motion of a patient anatomy, and to determine a breathing signal based on the determined change of depth values inside the at least one region over time; and wherein the output unit is configured to provide the determined breathing signal. The document also may be considered to disclose the corresponding method. SUMMARY OF THE INVENTION There may be a need to improve image quality. The object of the present invention is solved by the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the following described aspects of the invention apply also to the breathing status determination device, to the chest radiography imaging system, to the method for determining a breathing status of a patient, and to the computer program element. According to a first aspect of the present invention, there is provided a breathing status determination device, which comprises an input unit, a processing unit, and an output unit. The input unit is configured to receive a sequence of depth images that is continuously captured with a sensor having a field of view covering a torso of a patient positioned for a chest radiography image examination. The processing unit is configured to analyse the received sequence of depth images to determine a change of depth values inside at least one region-of-interest (ROI) over time that represents a motion of a patient anatomy orthogonal to an image plane of the sensor and/or a motion of a patient anatomy within an image plane of the sensor, and to determine a breathing signal based on the determined change of depth values inside the at least one ROI over time. The processing unit is configured to determine a change of a mean depth value inside the at least one ROI to determine the breathing signal. The output unit is configured to provide the determined breathing signal. In other words, it is proposed to make use of a sequence of depth images that is continuously acquired to track a change of depth values inside one or more ROIs on the patient (e.g. on the patient's back, chest, and/or shoulder) to extract the patient's breathing signal. The sequence of depth images comprise a plurality of depth images arranged in time series. Each depth image may also be referred to as image data frame. The extracted breathing signal may be usable to guide or control the triggering of the image acquisition to achieve different levels of automation. Breathing changes the volume of the patient's thorax and leads to motion of different body parts, e.g. chest/abdomen, shoulders, etc., which is also referred to as breathing motion. Depending on patient orientation (e.g. PA/AP or LAT), these motion vectors could be parallel or