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EP-3847485-B1 - AN IMAGE SENSOR HAVING RADIATION DETECTORS OF DIFFERENT ORIENTATIONS

EP3847485B1EP 3847485 B1EP3847485 B1EP 3847485B1EP-3847485-B1

Inventors

  • CAO, Peiyan
  • LIU, Yurun

Dates

Publication Date
20260506
Application Date
20180907

Claims (15)

  1. A system comprising: a radiation source (109); and an image sensor (9000), the image sensor comprising: an electronic system (121) comprising a processor; a first radiation detector (100A) and a second radiation detector (100B), respectively comprising a planar surface (103A, 103B) configured to receive radiation from the radiation source, wherein the planar surface (103A) of the first radiation detector and the planar surface (103B) of the second radiation detector are not parallel; wherein the image sensor is configured to capture, by using the first radiation detector and the second radiation detector and with the radiation, images of portions of a scene (50) at the positions respectively, and wherein the processor is configured to form an image of the scene by stitching the images of the portions; the system being characterized in further comprising an actuator (500) configured to move the first radiation detector and the second radiation detector to a plurality of positions relative to the radiation source, the image sensor being configured such that a relative position of the first radiation detector with respect to the second radiation detector remains the same at the plurality of positions.
  2. The system of claim 1, wherein the image sensor is further configured such that the relative position of the first radiation detector with respect to the second radiation detector remains the same while the first radiation detector and the second radiation detector move from one of the plurality of positions to another or wherein the first radiation detector and the second radiation detector are bonded to a same support.
  3. The system of claim 1, wherein the actuator is configured to move the first radiation detector and the second radiation detector relative to the radiation source by rotation about a first axis relative to the radiation source.
  4. The system of claim 3, wherein the first axis is parallel to the planar surface of the first radiation detector and the planar surface of the second radiation detector.
  5. The system of claim 3, wherein the actuator is configured to move the first radiation detector and the second radiation detector relative to the radiation source by rotation about a second axis relative to the radiation source; wherein the second axis is different from the first axis.
  6. The system of claim 1, wherein the actuator is configured to move the first radiation detector and the second radiation detector relative to the radiation source by translation along a first direction relative to the radiation source.
  7. The system of claim 6, wherein the first direction is parallel to the planar surface of the first radiation detector and the planar surface of the second radiation detector.
  8. The system of claim 6, wherein the actuator is configured to move the first radiation detector and the second radiation detector relative to the radiation source by translation along a second direction relative to the radiation source; wherein the second direction is different from the first direction.
  9. A method comprising: Capturing a first image of a first portion of a scene (50), by using a first radiation detector (100A) and a second radiation detector (100B) of an image sensor (9000), and with radiation from a radiation source (109), while the first radiation detector and the second radiation detector are at a first position relative to the radiation source; capturing a second image of a second portion of a scene, by using the first radiation detector and the second radiation detector, and with the radiation from the radiation source, while the first radiation detector and the second radiation detector are at a second position relative to the radiation source; forming an image of the scene by stitching the first image and the second image; wherein a first radiation detector and a second radiation detector respectively comprise a planar surface (103A, 103B) configured to receive radiation from a radiation source; wherein the planar surface (103A) of the first radiation detector and the planar surface (103B) of the second radiation detector are not parallel; characterized in that a relative position of the first radiation detector with respect to the second radiation detector remains the same at the first position and the second position.
  10. The method of claim 9, further comprising moving the first radiation detector and the second radiation detector from the first position to the second position by rotating the first radiation detector and the second radiation detector about a first axis relative to the radiation source.
  11. The method of claim 10, wherein the first axis is parallel to the planar surface of the first radiation detector and the planar surface of the second radiation detector.
  12. The method of claim 10, wherein moving the first radiation detector and the second radiation detector from the first position to the second position is further by rotating the first radiation detector and the second radiation detector about a second axis relative to the radiation source; wherein the second axis is different from the first axis.
  13. The method of claim 9, further comprising moving the first radiation detector and the second radiation detector from the first position to the second position by translating the first radiation detector and the second radiation detector along a first direction relative to the radiation source.
  14. The method of claim 13, wherein the first direction is parallel to the planar surface of the first radiation detector and the planar surface of the second radiation detector; or wherein moving the first radiation detector and the second radiation detector from the first position to the second position is further by translating the first radiation detector and the second radiation detector along a second direction relative to the radiation source; wherein the second direction is different from the first direction.
  15. The method of claim 10 or claim 13, wherein the relative position of the first radiation detector with respect to the second radiation detector remains the same while the first radiation detector and the second radiation detector are moved from the first position to the second position or wherein the first radiation detector and the second radiation detector are bonded to a same support.

Description

Background Radiation detectors may be devices used to measure the flux, spatial distribution, spectrum or other properties of radiations. Radiation detectors may be used for many applications. One important application is imaging. Radiation imaging is a radiography technique and can be used to reveal the internal structure of a non-uniformly composed and opaque object such as the human body. Early radiation detectors for imaging include photographic plates and photographic films. A photographic plate may be a glass plate with a coating of light-sensitive emulsion. Although photographic plates were replaced by photographic films, they may still be used in special situations due to the superior quality they offer and their extreme stability. A photographic film may be a plastic film (e.g., a strip or sheet) with a coating of light-sensitive emulsion. In the 1980s, photostimulable phosphor plates (PSP plates) became available. A PSP plate may contain a phosphor material with color centers in its lattice. When the PSP plate is exposed to radiation, electrons excited by radiation are trapped in the color centers until they are stimulated by a laser beam scanning over the plate surface. As the plate is scanned by laser, trapped excited electrons give off light, which is collected by a photomultiplier tube. The collected light is converted into a digital image. In contrast to photographic plates and photographic films, PSP plates can be reused. Another kind of radiation detectors are radiation image intensifiers. Components of a radiation image intensifier are usually sealed in a vacuum. In contrast to photographic plates, photographic films, and PSP plates, Radiation image intensifiers may produce real-time images, i.e., do not require post-exposure processing to produce images. Radiation first hits an input phosphor (e.g., cesium iodide) and is converted to visible light. The visible light then hits a photocathode (e.g., a thin metal layer containing cesium and antimony compounds) and causes emission of electrons. The number of emitted electrons is proportional to the intensity of the incident Radiation. The emitted electrons are projected, through electron optics, onto an output phosphor and cause the output phosphor to produce a visible-light image. Scintillators operate somewhat similarly to radiation image intensifiers in that scintillators (e.g., sodium iodide) absorb radiation and emit visible light, which can then be detected by a suitable image sensor for visible light. In scintillators, the visible light spreads and scatters in all directions and thus reduces spatial resolution. Reducing the scintillator thickness helps to improve the spatial resolution but also reduces absorption of radiation. A scintillator thus has to strike a compromise between absorption efficiency and resolution. Semiconductor radiation detectors largely overcome this problem by direct conversion of radiation into electric signals. A semiconductor radiation detector may include a semiconductor layer that absorbs radiation in wavelengths of interest. When a radiation particle is absorbed in the semiconductor layer, multiple charge carriers (e.g., electrons and holes) are generated and swept under an electric field towards electric contacts on the semiconductor layer. Cumbersome heat management required in currently available semiconductor radiation detectors (e.g., Medipix) can make a detector with a large area and a large number of pixels difficult or impossible to produce. JP 2004/037418 discloses a nuclear medicine diagnostic apparatus comprising a plurality of movable detectors. Two detectors are arranged at opposing positions either side of a subject. The remaining detector is arranged at a location which covers both a part of the subject and forms an approximate U-shape with the other detectors. The detectors are moved and rotated by 180° around the subject to collect data. Summary According to a first aspect of the present invention, there is provided a system comprising: a radiation source; and an image sensor, the image sensor comprising: an electronic system comprising a processor; a first radiation detector and a second radiation detector, respectively comprising a planar surface configured to receive radiation from a radiation source; wherein the planar surface of the first radiation detector and the planar surface of the second radiation detector are not parallel; an actuator configured to move the first radiation detector and the second radiation detector to a plurality of positions relative to the radiation source, the image sensor being configured such that a relative position of the first radiation detector with respect to the second radiation detector remains the same at the plurality of positions; wherein the image sensor is configured to capture, by using the first radiation detector and the second radiation detector and with the radiation, images of portions of a scene at the positions respectively, and wherein