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EP-4734822-A1 - LIGHTING FOR A MEDICAL IMAGING SYSTEM

EP4734822A1EP 4734822 A1EP4734822 A1EP 4734822A1EP-4734822-A1

Abstract

A system comprising a medical imaging unit having an imaging zone defined by an interior region of a bore, and further comprising a lighting apparatus comprising one or more light output areas disposed within the bore. In one set of embodiments, there are provided a plurality of light output areas, distributed at different positions along an axial direction of the bore.In some embodiments, a controller is included to control a light output setting of each of the plurality of light output areas so as to form a controlled spatial light distribution from a composite of the light fields of the plurality of light output areas. In some embodiments, an x-ray input/output window is replaced with an x-ray transmissive and light diffusive panel for performing dual functions of permitting x-ray communication between an imaging apparatus and the imaging zone and forming at least one wide-area diffuse/homogenous light output area.

Inventors

  • WEISS, STEFFEN
  • SENEGAS, Julien Thomas
  • WIRTZ, DANIEL

Assignees

  • Koninklijke Philips N.V.

Dates

Publication Date
20260506
Application Date
20240620

Claims (15)

  1. 1. A system (10), comprising: a medical imaging unit (12) comprising a housing (14) and an imaging apparatus (16, 17, 18), wherein the housing comprises a bore (22) configured to receive a support element (26) configured to receive a patient, and wherein the imaging apparatus is for probing an imaging zone (24) within the bore, and wherein an axial axis of the bore defines a z-direction; wherein the support element is movable along the z direction wherein the system comprises at least one camera for imaging the patient and having a field of view which spans at least the imaging zone within the imaging unit bore, a lighting apparatus (30) configured to provide illumination inside the bore (22) of the imaging unit, the lighting apparatus comprising a plurality of independently controllable light output areas (32a, 32b, 32c) disposed inside the bore of the imaging unit, the plurality of light output areas being spaced from one another in the z-direction; a lighting controller (42) adapted to implement a lighting control operation comprising individually controlling a setting of at least one light output property of each of the light output areas (32a, 32b, 32c) so as to form a controlled light intensity distribution as a function of z-position in the bore which reduces the light variation over patient when the support element is moved within the imaging unit bore along the z direction
  2. 2. The system of claim 1, wherein: the at least one light output property includes a brightness level of each of the light output areas; and/or the at least one light output property include a color of the light output of each of the light output areas.
  3. 3. The system of claim 1 or 2, wherein each of the light output areas comprises at least one light output strip extending part or all of the way around an interior circumference of the bore.
  4. 4. The system of any of claims 1-3, wherein the lighting apparatus includes at least one light diffusion panel having a light output surface, and wherein at least one of the light output areas is formed by at least a portion of the light output surface of the at least one light diffusion panel.
  5. 5. The system of claim 4, wherein each of two or more of the plurality of light output areas is formed by a respective area of the light output surface of the at least one light diffusion panel.
  6. 6. The system of claim 4 or 5, wherein the light diffusion panel has a front light output face and a rear face opposite the front light output face, and wherein the lighting apparatus comprises a plurality of light sources arranged to couple light into the light diffusion panel through the rear face in order to form the plurality of light output areas at the front light output face.
  7. 7. The system of claim 4, wherein the lighting apparatus comprises one or more light sources arranged to couple light into edges of the light diffusion panel for transmission across the panel.
  8. 8. The system of any of claims 1-7, wherein the medical imaging unit is a tomographic, e.g. computed tomography, CT, imaging unit comprising a gantry for carrying an x-ray generator and x-ray detector for probing the imaging zone, wherein an axial axis of the bore defines a z-direction; wherein the CT imaging unit comprises an x-ray input/output window extending circumferentially around at least a portion of an interior face of the bore for facilitating x-ray communication between the imaging zone and an x-ray generator and detector carried by the gantry; and wherein at least one of the plurality of light output areas is formed by at least a portion of an exterior face of the x-ray input/output window, and preferably wherein the x-ray input/output window comprises a light diffusion panel.
  9. 9. The system of any preceding claim, wherein the lighting control operation further comprises: identifying for each of a plurality of points, x, across a field of interest (ROI): an ambient light contribution, P 0 x). at the point; a light contribution, a ( P ( (x). at the point provided by each of the plurality of light output areas, i, as a function of the at least one controllable setting, a,, of a light output property of the light output area, wherein each light contribution, a ( P ( (x). includes at least a measured value of the at least one light output property at the relevant point; and running an optimization procedure for fitting values of the setting, of the light output property for each of the light output areas, the optimization procedure configured for maximizing homogeneity in the light output property across the field of interest, wherein a value of the light output property at each point comprises a sum of the ambient light contribution, P 0 x). at that point and the light contributions, a ( P ( (x). by the plurality of light output areas.
  10. 10. The system of claim 9, wherein the optimization procedure comprises: defining a target value, a Q (x), for the light output property for each point, x, of the field of interest, wherein preferably the target value is the same for every point, x. fitting the values of the controllable setting, of the light output property for each light output area so as to minimize, for each point x, a difference measure between the target value, a 0 (x). and a sum of the ambient light contribution at that point, P 0 x). and the aggregate of the light contributions, a ( P ( (x). provided by each of the plurality of light output areas at that point as a function of the setting,
  11. 11. The system of claim 9 or 10, wherein the optimization procedure comprises performing the following minimization: where x is an index of the point in the field of interest, a Q (x) is a target function for the light output property for each point, x, P Q (x) is the ambient light contribution at each point, x, Pi (x) is the light contribution at each point, x, by each light output area, i, when the light output area is operated at a maximum value (a, = I ) of the controllable setting of the light output property, and is a fitting parameter representing a value of the controllable setting of the light output property of the light output area, i, where a^s a fractional weighting 0 < a t < 1.
  12. 12. The system of any of claims 9-11, wherein each light output area has two or more independently controllable light output property settings, and wherein the optimization procedure is run separately for each light output property.
  13. 13. The system of any of claims 9-12, wherein the system comprises at least one camera for imaging a patient and having a field of view which spans at least the imaging zone within the imaging unit bore, wherein the field of interest is at least a sub-zone of the field of view of the camera, wherein the light contributions, PQ X). Pi(x , at each point of the field of interest are derived based on one or more images obtained with the camera.
  14. 14. The system of any of claim 13, wherein the optimization procedure comprises receiving an ambient reference image generated by a camera having a field of view which spans at least the imaging zone within the imaging unit bore, wherein the ambient reference image depicts the field of view with each of the plurality of light output areas deactivated, and wherein the ambient light contribution, P 0 x). at each of the plurality of points, x, across the field of interest is derived from pixel values of said ambient reference image; and wherein the optimization procedure comprises receiving, for each of the light output areas, a respective reference image generated by a camera having a field of view which spans at least the imaging zone within the imaging unit bore, wherein each reference image depicts the field of view with a single respective one of each of the plurality of light output areas activated at a maximum value (a, = I ) of the controllable setting of the light output property, and wherein the light contribution, at each of the plurality of points, x, across the field of interest for each light output area, i, is derived from pixel values of said reference images.
  15. 15. The system of any preceding claim, further comprising at least one camera for imaging a patient and having a field of view which spans at least the imaging zone within the imaging unit bore, and optionally wherein the system comprises at least two cameras, one arranged for imaging each respective end of the imaging unit bore.

Description

LIGHTING FOR A MEDICAL IMAGING SYSTEM FIELD OF THE INVENTION The present invention relates to the field of medical imaging systems. BACKGROUND OF THE INVENTION Various medical imaging modalities involve a patient’s body being positioned within an imaging zone, for instance defined by an interior of a bore. Such imaging modalities include for example computed tomography (CT) imaging, magnetic resonance (MR) imaging, positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These imaging modalities allow for detailed visualization of the body's internal structures and functions, aiding in accurate diagnosis and treatment planning. In some imaging procedures, it is necessary to acquire images while the patient is in a certain respiratory phase or state, or when certain physiological parameters meet defined criteria. For example, abdominal and cardiac CT imaging is usually performed in short breath-holds to avoid any loss of image quality due to respiratory motion. Similar procedures are also performed in MRI imaging. State-of-the-art CT and MRI imaging systems do not monitor the respiratory state of the patient, for example to track whether and when the patient is in a breath-hold state. One approach to tracking vital parameters such as respiratory and cardiac rhythm would be to use a physical sensor attached to the patient. This has been demonstrated for a range of medical applications. An approach which may be preferable is to use camera-based tracking of vital parameters such as respiratory and cardiac rhythm. Some such systems exist in the art and, in particular, can monitor the respiratory state of a patient in an MR system with a camera. The system may also trigger MR acquisition as soon as the patient starts a breath-hold. This is known as respiratory gating. At least one wide-angle camera is positioned at an end of the bore to image the patient. Similar principle might also be applied to CT imaging. Tracking of other physiological parameters might also be of value in assisting medical imaging procedures. In addition to tracking respiration, camera imagery can also usefully be used to detect motion of the patient, as a means for detecting possible motion artefacts in the image data. Thus, the use of cameras for motion monitoring during medical imaging has technical application. In such a context, the general aim is to derive a measure of motion of the body part that is currently in the image acquisition zone (e.g. within the bore of the scanner). In a simplest case, this may be used to indicate to an operator which of multiple acquired slices of a CT dataset may have image quality impaired by motion. In some cases, the motion signal might be used to trigger cessation of the imaging procedure. Respiratory monitoring involves the detection of sub-millimeter motion of the abdomen and chest. It’s application in CT imaging in particular is demanding because CT acquisition is frequently performed with a moving patient support element such as a couch or a patient table. SUMMARY OF THE INVENTION One significant difficulty in detection of motion from camera images is the problem of intensity variations across the field of view. Since part of the patient may be within the bore of a scanner, this part is under shadow, while other parts of the body are illuminated by the ambient light. Variations in intensity cause difficulties in automated analysis of the images. This is in part also caused by the fact that only ambient illumination is available. This naturally illuminates the CT acquisition zone inside the bore much less than the rest of the scene. Furthermore, for best performance, in some cases, camera and lenses with a very wide FOV may be chosen to cover the wide motion range of the patient table. Such optical systems are subject to strong geometrical distortions, which also induce strong brightness variation across the image since light from large solid angles is projected into relatively few pixels towards the rim of the image. This can lead to saturation of the raw image in these areas while the central image region inside the bore is poorly illuminated. It is particularly demanding to detect sub-millimeter respiratory motion of a patient while moving on a table through these image regions with strong intensity variations and geometrical distortions. In view of the above challenges, it is the recognition of the inventors that improved motion and respiration tracking may be achieved by providing a specialized lighting arrangement which can help to balance the strong intensity variations. The invention is defined by the claims. According to examples in accordance with an aspect of the invention, there is provided a system comprising a medical imaging unit comprising a housing and an imaging apparatus, wherein the housing comprises a bore for receiving an object to be imaged, and wherein the imaging apparatus is for probing an imaging zone within the bore, and wherein an axi