WO2019135676A1 - Collimateur actif pour émission de positrons et tomodensitométrie à émission de photons uniques - Google Patents

Collimateur actif pour émission de positrons et tomodensitométrie à émission de photons uniques Download PDF

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Publication number
WO2019135676A1
WO2019135676A1 PCT/NL2018/050893 NL2018050893W WO2019135676A1 WO 2019135676 A1 WO2019135676 A1 WO 2019135676A1 NL 2018050893 W NL2018050893 W NL 2018050893W WO 2019135676 A1 WO2019135676 A1 WO 2019135676A1
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Prior art keywords
collimator
scintillator
bars
active
aperture
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PCT/NL2018/050893
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English (en)
Inventor
Jeremy Michael Cooney BROWN
Dennis Robert Schaart
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Technische Universiteit Delft
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Publication of WO2019135676A1 publication Critical patent/WO2019135676A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
    • A61B6/4258—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector for detecting non x-ray radiation, e.g. gamma radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/06—Diaphragms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/44—Constructional features of apparatus for radiation diagnosis
    • A61B6/4417—Constructional features of apparatus for radiation diagnosis related to combined acquisition of different diagnostic modalities
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
    • G01T1/164—Scintigraphy
    • G01T1/1641—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
    • G01T1/1648—Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/037—Emission tomography

Definitions

  • the invention relates to an active collimator system for gamma ray detection.
  • the invention further relates to a nuclear imaging system comprising such active collimator system.
  • a preferred omni -tomography system of the invention comprises two or more imaging modalities operably configured for concurrent signal acquisition for performing ROI-targeted reconstruction and contained in a single gantry with a first inner ring as a permanent magnet; a second middle ring containing an x-ray tube, detector array, and a pair of SPECT detectors; and a third outer ring for containing PET crystals and electronics.
  • Omni-tomography offers great synergy in vivo for diagnosis, intervention, and drug development, and can be made versatile and cost-effective, and as such is expected to become an unprecedented imaging platform for development of systems biology and modern medicine.
  • US20100096555A1 describes a method and apparatus for detecting radiation including x-ray, gamma ray, and particle radiation for nuclear medicine, radiographic imaging, material composition analysis, high energy physics, container inspection, mine detection and astronomy. It further describes a detection system employing one or more detector modules comprising edge-on scintillator detectors with sub-aperture resolution (SAR) capability employed, e.g., in nuclear medicine, such as radiation therapy portal imaging, nuclear remediation, mine detection, container inspection, and high energy physics and astronomy. It also describes edge- on imaging probe detectors for use in nuclear medicine, such as radiation therapy portal imaging, or for use in nuclear remediation, mine detection, container inspection, and high energy physics and astronomy.
  • SAR sub-aperture resolution
  • US8519343B1 describes an apparatus for detecting and locating a source of gamma rays of energies ranging from 10-20 keV to several MeV's includes plural gamma ray detectors arranged in a generally closed extended array so as to provide Compton scattering imaging and coded aperture imaging simultaneously. First detectors are arranged in a spaced manner about a surface defining the closed extended array which may be in the form a circle, a sphere, a square, a pentagon or higher order polygon.
  • Some of the gamma rays are absorbed by the first detectors closest to the gamma source in Compton scattering, while the photons that go unabsorbed by passing through gaps disposed between adjacent first detectors are incident upon second detectors disposed on the side farthest from the gamma ray source, where the first spaced detectors form a coded aperture array for two or three dimensional gamma ray source detection.
  • Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) systems are nuclear imaging systems.
  • Nuclear imaging is a branch of nuclear medicine.
  • Nuclear medicine in general, concerns the use of radioactive compounds to diagnose and treat diseases.
  • Nuclear imaging specifically, is focused on detecting radiation from radioactive sources within a subject.
  • the radioactive source is typically an administered radionuclide-carrying marker that targets a specific physiological process, resulting in local accumulations. These accumulations can then be imaged non-invasively as the radionuclides emit gamma rays.
  • the gamma rays can be detected with a 2D scintigraphy system, but are most commonly detected using either PET or SPECT systems.
  • PET and SPECT systems may also be combined with other imaging systems providing concurrent anatomical information.
  • the nuclear imaging systems PET and SPECT are combined with CT, and with MRI, resulting in PET-CT, PET-MRI, SPECT-CT, and SPECT-MRI hybrid imaging systems.
  • SPECT and PET are the two predominant in-vivo molecular imaging modalities for small animals and humans.
  • a molecular vector is labeled with a gamma ray emitting radionuclide, administered to the subject, and may be imaged via the use of a direct or coded aperture, composed of a highly attenuating material, to restrict the solid angle of radiation incident upon the surface of a position resolving, or position-and-energy-resolving, radiation detector at some distance from the subject.
  • a Line of Response (LoR) that estimates its possible origin can be constructed utilizing the interaction location and estimated coded aperture opening it passed through.
  • a molecular vector is labeled with a positron emitting radionuclide and two co-linear 511 keV gamma rays are generated from its annihilation with an electron nearby the site of emission in the subject.
  • the subject is placed into the center of a ring of position-and-energy-resolving radiation detectors configured to detect the pair of 511 keV gamma rays for each positron annihilation.
  • a LoR can be constructed for their interaction locations estimating the site of positron annihilation and the location of the molecular vector.
  • the backprojection of multiple LoRs enables for the distribution of the molecular vector within the subject to be estimated and with the aid of specialized image reconstaiction programs quantitative estimates can be achieved.
  • a simplest approach could be to set up a small animal/patient bed with a SPECT and PET imaging gantry at each end. Whilst this approach allows for the performance of both imaging modalities to remain unchanged, it is impossible to image simultaneously and to compare the spatiotemporal concentration of each SPECT and PET molecular vector in vivo.
  • Another approach for hybridized systems could be to either utilize partial PET rings with collimated gamma ray detectors inserted in the removed regions, or to utilize thick solid metal coded aperture collimators capable of stopping 511 keV gamma rays to replace standard SPECT collimators.
  • the end results may be systems which can image SPECT and PET molecular vectors simultaneously, but at a severe trade-off in performance between the two (decrease of sensitivity for PET and of spatial resolution for SPECT).
  • SPECT and PET are powerful and commonly used imaging technologies in clinical and research settings. In these settings, a subject - a patient or animal - is administered a radionuclide marker that will concentrate in the body in a tissue-dependent manner, for example, cancer cells may become enriched with the marker. The marker will emit gamma rays of which the origin point can then be detected through nuclear imaging systems, such as SPECT or PET systems.
  • PET systems localize the origin point of a gamma ray by taking advantage of an annihilation event occurring when a positron encounters an electron; two 511 keV gamma rays are simultaneously emitted in roughly opposite directions. When both these gamma rays are detected by two different detector elements of the PET system, their origin point can be estimated as it has to roughly be on a line between the two detector elements.
  • SPECT systems detect gamma rays without a paired gamma ray.
  • SPECT systems rely on a collimator upstream of the gamma ray detectors. Each collimator hole only permits gamma rays originating from a small area within the subject, thereby directly providing positional information for each detected gamma ray.
  • PET and SPECT collimators needing to reject the vast majority of gamma rays in order to locate the emission origin, whereas PET detectors need to detect the vast majority of gamma rays as the localization depends on detecting two gamma rays from the same annihilation event.
  • the present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
  • the present invention encompasses the concept of active collimation to enable e.g. simultaneous SPECT and PET molecular vector imaging with a reduced trade-off in performance.
  • rows of bar gamma ray detectors are arranged in a layered manner. These layered rows of bar gamma ray detectors enable for coded apertures to be constructed.
  • the coded collimator aperture limits the solid angle which emitted gamma rays from the SPECT molecular vector can pass through, thereby replicating the image formation process key to SPECT imaging.
  • the 511 keV gamma rays from the PET tracer that interact with them have their energy deposition, interaction location and time point recorded.
  • a detected gamma ray can then be paired with its’ partner co-linear 511 keV gamma ray detected by another radiation detector to perform PET reconstruction.
  • the result is a SPECT-PET molecular vector imaging system with near-zero loss of PET sensitivity whilst achieving similar SPECT resolution to a traditional metal collimator design.
  • the current invention addresses these incompatibilities through the design of an‘active collimator’.
  • This active collimator may carry the function of a normal collimator for SPECT analysis, in that only gamma rays from a small area within the subject pass through. However, rather than blocking the remaining gamma rays, it detects them. In particular, it detects the 511 keV gamma rays required for PET analysis.
  • the invention provides an active collimator system, especially an active collimator system for PET and/or SPECT imaging, having a collimator aperture (“aperture”), especially a coded collimator aperture, for use in a nuclear imaging system, the active collimator system comprising scintillator bars (“bars”) and photosensor units, wherein the scintillator bars are configured to absorb incoming gamma rays and scintillate, thereby emitting scintillation photons, wherein the scintillator bars are further configured to provide the collimator aperture, especially the coded collimator aperture, wherein the photosensor units are configured to detect the scintillation photons, and wherein the photosensor units are directed to scintillator bar ends of the scintillator bars.
  • aperture collimator aperture
  • coded collimator aperture for use in a nuclear imaging system
  • the active collimator system comprising scintillator bars (“bars”) and photosensor units, wherein the scintill
  • This invention enables the simultaneous imaging of a subject using both SPECT and PET molecular vectors (SPECT-PET) with reduced drawbacks relative to current systems for SPECT-PET imaging.
  • the active collimator may serve as collimator for SPECT imaging, and at the same time the active collimator may serve as gamma ray detector for PET imaging.
  • an encompassing hybrid SPECT-PET imaging system may have a combined SPECT-PET detector surface, rather than the separation of SPECT and PET detector surfaces found in alternative SPECT-PET systems.
  • alternative SPECT and SPECT-PET systems may rely on metal collimators, which are typically incompatible with Magnetic Resonance Imaging (MRI).
  • MRI Magnetic Resonance Imaging
  • the present invention may in embodiments also encompass MRI-compatible collimators.
  • the present active collimator system may especially be useful for combined SPECT-PET systems, especially systems with additional imaging technologies such as with Computed Tomography (CT): SPECT- PET-CT; and with MRI: SPECT-PET-MRI.
  • CT Computed Tomography
  • MRI SPECT-PET-MRI
  • the active collimator system may comprise an active collimator system (configured) for PET and/or SPECT imaging, especially for PET and SPECT imaging, such as for PET-SPECT imaging.
  • the active collimator system may comprise an active collimator system (configured) for one or more of PET, SPECT, CT, and MRI imaging, especially configured for PET and/or SPECT imaging, such as for PET and SPECT imaging, and for CT and/or MRI imaging.
  • a gamma ray is a type of photon.
  • Gamma rays are defined according to two distinct definitions, both of which are used in the nuclear imaging field and herein. According to a first definition, gamma rays are the highest energy photons. Gamma rays have a partial overlap in the lower part of their energy spectnmi with the highest energy (characteristic) X-rays, and gamma rays have no defined upper energy limit. This definition regards any photon with an energy above approximately 100 keV as a gamma ray.
  • a gamma ray is a photon emitted during the radioactive decay of an atomic nucleus from a high-energy state to a lower-energy state.
  • This latter definition defines gamma rays by their origin irrespective of their energy. Following this definition, gamma rays do not have a defined energy range.
  • Radionuclides used for SPECT emit gamma rays following the radioactive decay of an atomic nucleus.
  • Such a gamma ray may have an energy below 100 keV, especially 70-90 keV, but also above 100 keV, especially 100-1000 keV, more especially gamma rays with an energy of 140 keV, 159 keV, 171 keV, 245 keV, 364 keV, 537 keV or 637 keV.
  • major radiotracers such as based on T1-201, Tc-99m, 1-123, 1-131, In-l l l, F-18, C-l l, etc., may be of interest.
  • energies in the range of about 10 keV to 10 MeV may be of interest.
  • Radionuclides used for PET can emit both gamma rays and positrons.
  • positron annihilation takes place.
  • positron annihilation event two 511 keV gamma rays are emitted in roughly opposite directions.
  • a characteristic X-ray is especially generated from the transition of an atomic bound electron to a lower, empty atomic state. These energies of these X-rays are dependent on the atom they come from and may be used in nuclear imaging systems, for example, in the case of iodine based radiotracers used in SPECT imaging.
  • the term‘gamma ray’ herein relates to any photon that is used in nuclear imaging, irrespective of origin or energy (and also includes (characteristic) X-rays).
  • a collimator is a device configured to control one or more of beam (of rays) direction, beam (of rays) width, and beam (of rays) path.
  • the collimator comprises one or more apertures through which a photon can pass, and it comprises a collimator material configured to absorb photons.
  • the one or more apertures are configured to provide paths stretching between two opposite sides of the collimator along which a photon can travel without encountering collimator material.
  • a photon travelling along a desired path may pass the aperture, such as a path coinciding with an optical axis of the collimator.
  • a photon not travelling along a desired path may not pass the collimator, and may be absorbed by the collimator material.
  • the collimator is configured to filter photons such that the outgoing beam of photons are more focused or narrowed, especially such that only photons with desired incident angles are accepted, more especially such that the directions of the outgoing photons are more parallel than upstream of the collimator.
  • High energy photons - such as gamma rays - may penetrate solid materials, i.e. pass through solid materials without being absorbed, especially high energy photons may penetrate the collimator material. Penetration of the collimator material is undesired as a photon not travelling along a desired path may pass the collimator and appear accepted. Therefore, the collimator is configured to decrease the likelihood of penetration. The likelihood of penetration may be reduced by increasing the thickness of the collimator material. The likelihood of penetration may be reduced by the choice of collimator material.
  • the collimator material in prior art solutions
  • the invention provides an active collimator system.
  • the active collimator system at least comprises a collimator comprising scintillator bars.
  • the active collimator system may further comprise a light guide.
  • the active collimator may comprise photosensor units. Another term for“light guide” may also be“wave guide”.
  • the collimator has a collimator aperture.
  • the collimator aperture is defined by the scintillator bars.
  • the collimator may have a collimator aperture face, which aperture face essentially defines the collimator aperture.
  • the aperture face is essentially defined by the collimator bars, more especially by their scintillator bar faces (see also below).
  • the collimator bars of the collimator system are configured in such a way, that a collimator with a collimator aperture is provided (thereby).
  • the collimator has a coded collimator aperture.
  • Coded apertures or coded-aperture masks are grids, gratings, or other patterns, especially of materials opaque to various wavelengths of light.
  • the wavelengths are usually high-energy radiation such as X-rays and gamma rays.
  • a coded "shadow" is cast upon a plane. The properties of the original light sources can then be mathematically reconstructed from this shadow.
  • Coded apertures are used in X- and gamma ray imaging systems, because these high-energy rays cannot be focused with lenses or mirrors.
  • the term“coded” or“coded aperture” and similar terms especially refer to the aperture that is provided by the scintillator bars.
  • the term“coded aperture” may (thus) refer to an aperture defined by bars but may also refer to an arrangement of a plurality of apertures (defined by the bars.
  • the term“aperture” may (thus) also refer to a plurality of apertures.
  • the collimator as described herein may include a single aperture but may in other embodiments comprise a plurality of apertures.
  • the coded collimator aperture is configured to selectively accept gamma rays, i.e., to selectively allow gamma rays to pass, especially the coded collimator aperture accepts gamma rays based on their incidence angle and location.
  • the shape of the coded collimator aperture may approximate the shape of a parallel hole collimator, a slant hole collimator, a converging collimator, a diverging collimator, a fan beam collimator, a single pass diverging collimator, a pinhole collimator, or any other shape resulting in the collimation of gamma rays.
  • the collimator may include a single aperture or may include a plurality of apertures. In the latter embodiment, the apertures will in general have essentially identical dimensions.
  • the coded collimator aperture has a parallel-hole shape, a pinhole shape, a converging shape, or a diverging shape.
  • the terms“shape” may also indicate that the collimator aperture approximates such shape, as will be clear to a person skilled in the art. Therefore, in embodiments the coded collimator aperture approximates the shape of a parallel-hole shape, of a pinhole shape, of a converging shape, or of a diverging shape. In specific embodiments, a combination of two or more different types of aperture may be applied (within the same collimator system).
  • the active collimator system may contain one or more metal inserts to further define the coded collimator aperture.
  • the metal inserts may further define the coded collimator aperture by one or more of narrowing, widening, focusing, and/or slanting the aperture.
  • the metal inserts may be arranged between two or more adjacent (scintillator) bars.
  • the metal inserts may partially cover one or more faces of one or more bars.
  • the metal inserts may fully cover one or more faces of one or more bars.
  • the metal inserts may be (elongated) plates.
  • metal inserts may be hollow, having cross-sections e.g. selected from the circular, square, hexagonal, etc. cross-sections.
  • the metal inserts may have a variable cross-section (along an optical axis). Especially, the metal inserts may have a static cross-section. The metal inserts may all have the same shape. Especially, the metal inserts may have different shapes.
  • the metal inserts may especially comprise one or more of platinum, tungsten, lead, gold, iridium, rhenium, tantalum, rhodium, aithenium and molybdenum, especially platinum, tungsten, lead, molybdenum and gold, more especially two or more of platinum, tungsten, lead, molybdenum and gold, e.g. the metal inserts may comprise both tungsten and gold.
  • the shape of the coded collimator aperture may be further defined through one or more metal inserts.
  • the metal insert may comprise one or more of platinum, tungsten, lead, gold, iridium, rhenium, tantalum, rhodium, ruthenium and molybdenum, especially platinum, tungsten, lead, molybdenum and gold.
  • Especially suitable materials have a high density, are non-toxic, and are stable in air.
  • the active collimator system exclusively contains noil-magnetic materials.
  • the scintillator bars are especially configured to absorb gamma rays and emit a number of scintillation photons depending on the energy of the gamma ray.
  • the scintillator bars are configured to channel the scintillation photons to the (end-mounted) photosensor unit.
  • each scintillator bar may be configured to distribute the scintillation photons to one (or two) of two end-mounted photosensor units depending on the distance of the scintillation event to each photosensor unit. More especially, the scintillator bars are configured to channel more scintillation photons to a photosensor unit that is closer to the scintillation event (than to photosensor units that are more remote).
  • the scintillator bars may especially be scintillator crystal bars.
  • the scintillator bars may especially be scintillator ceramic bars.
  • the bars may be single crystals or ceramics. Combinations of a plurality of different bars, with e.g. bars being single crystals and bars being ceramic, may also be applied.
  • the scintillator bar comprises one or more scintillating materials, especially a single scintillation material.
  • the scintillator bar may comprise one or more of thallium activated sodium iodide (NATTI), bismuth germinate (BGO), cesium activated yttrium aluminum garnet (YAG:Ce), cesium activated lutetium aluminum garnet (LuAG:Ce), cadmium zinc telluride (CZT), lanthanum bromide (LaBr;,), REiSiOyCe, wherein RE comprises especially one or more of Y, La, Lu, Gd and/or other rare earth elements, especially at least one or more of Y and Lu , etc., more especially wherein RE SiOyCe comprises Lu2- x Y x Si05:Ce (LYSO).
  • NATTI thallium activated sodium iodide
  • BGO bismuth germinate
  • YAG:Ce cesium activated yt
  • the scintillator bar may comprise AABOn material, wherein A comprise Bi and wherein M comprises one or more of Si and Ge, wherein at least part of M comprises Si.
  • the single crystalline or ceramic A4M3O 12 material comprises A4(Ge l-x Si x ) 3 O l 2 wherein 0. I ⁇ 1. especially wherein x is at least 0.9.
  • the single crystalline or ceramic A4M3O12 material comprises (Bii- y RE y ⁇ MsOn, wherein y is selected from the range of 0-0.2, and wherein RE refers to one or more rare earth elements.
  • the scintillator bars may have dimensions like a length selected from a few millimeters to centimeters, and a width and height selected of similar range. The width and height may vary over the length, but will in general be constant.
  • the scintillator bars may have a square or rectangular cross-section.
  • the bars may also have triangular cross-sections.
  • the bars may also have other polygonal cross- sections, especially isosceles hexagonal cross-sections and isosceles octagonal cross- sections.
  • the collimator system comprises a plurality of bars, e.g. a single collimator system may include in the range of 4-5,000,000, such as at least 16 bars, especially at least 64 scintillator bars.
  • the bars may also have different shapes, i.e. especially different cross-sectional shapes. Especially, however, essentially all bars may have essentially the same cross-sectional shapes and dimensions.
  • the bars are especially elongated, with an axis of elongation.
  • the bars are configured in layers, and the layers are stacked. Within a layer, the bars may especially be configured parallel. Parallel configured bars within the layer may touch each other. Alternatively or additionally, between (other) parallel bars there may be metal inserts. Alternatively or additionally, (other) parallel bars within the layer may not touch each other, e.g. for providing (part of) a collimator aperture.
  • the distance between adjacent non-touching parallel bars may vary in the layer. More especially, all adjacent non-touching parallel bars in the layer are separated by the same distance. Most especially, all parallel bars in the layer have the same width and the distance between adjacent non-touching parallel bar equals this width.
  • the succession of touching and non-touching adjacent parallel bars in the layer may partially follow one or more patterns, especially one or more of the patterns (N y T z ) n , and (T x N y T z ) n .
  • the bars in adjacent layers in the stack may be oriented perpendicular to each other.
  • an (AB) n stacking may be provided, with n being an integer of at least 2, such as at least 5, like at least 10, such as in the range of 5-500.
  • n being an integer of at least 2, such as at least 5, like at least 10, such as in the range of 5-500.
  • the terms“parallel” and“perpendicular” may especially refer to the orientation of the axes of elongation.
  • a pure (AB) n stacking may be provided but in other embodiments between one or more sets of AB, there may be one or more A or one or more B layers.
  • Such alternative embodiments may lead to a regular or an irregular arrangement of the layers, especially a regular arrangement, such as e.g. (ABB) repeat.
  • the scintillator bars in different layers may be different. More especially, in specific embodiments two (or more) scintillator bars in the same layer may be different. In specific embodiments the scintillator bars may have different shapes. Alternatively or additionally, in specific embodiments the scintillator bars may comprise different compositions of (one or more) scintillating materials.
  • the composition of scintillating materials of the scintillator bars may vary across layers, e.g., the scintillator bars in a first half of the stacked layers comprise a first composition of (one or more) scintillating materials, and the scintillator bars in a second half of the stacked layers comprise a second composition of (one or more) scintillating materials.
  • the collimator comprises a plurality of bars, wherein a subset of one or more, especially a plurality, of bars comprise LYSO, and wherein another subset of one or more, especially a plurality, of bars comprise BGO. In this way, resolution and/or detection range may further be enhanced. More especially, in specific embodiments the scintillator bars in the first half of the stacked layers comprise LYSO and the scintillator bars in the second half of the stacked layers comprises BGO.
  • the configuration of bars which provides the collimator with its collimator aperture may in embodiments have a cuboid symmetry, such as a cube.
  • the configuration, which may also be indicated as collimator may in embodiments have four side faces, which may essentially be parallel to an optical axis of the collimator.
  • the layers configured perpendicular to the optical axis may essentially be configured in a pure (AB) n stacking.
  • Side faces of the collimator are especially defined relative to the optical axis.
  • Outer planes are opposite ends of the collimator, and may especially be configured perpendicular to the optical axis. The distance between the opposite ends of the collimator may be defined as the length of the collimator.
  • a single photosensor unit may be directed to a side face.
  • a plurality of photosensor units may be configured downstream from a side face.
  • at least two photosensor units are configured under an angle (nog being 0°, 180° or 360°).
  • the photosensor unit may receive and detect photons (escaping from a bar (end) at the side face).
  • the photons may be received by the photosensor unit directly or the photons may propagate through a light guide before reaching the photosensor unit.
  • the photosensor unit(s) are functionally coupled with one or more side faces of the collimator.
  • photosensor units In general there will be the same number of photosensor units as side faces as this may provide the highest resolution. When a plurality of photosensor units per side face is applied, there may be the same number of sets of photosensor units as side faces. The number of photosensor in such set may differ from side to side, but may also be identical for each side to which photosensor are optically coupled.
  • the scintillator bars are configured in stacked layers, wherein scintillator bars in adjacent stacked layers are configured orthogonal.
  • This may provide a cross-section that is rectangular, especially square.
  • this may especially provide a cuboid collimator (unit). It is, however, not necessary that the collimator has a cuboid symmetry.
  • Other symmetries, such as prismatic may also be possible.
  • the scintillator bars are configured in stacked layers, wherein scintillator bars in adjacent stacked layers are configured under an angle selected from the range of k*l5, wherein k is selected from 1, 2, 3, 4, 6, 8, 10 or 12, especially 1, 2, 3, 4, 6, 8 or 10, more especially 2, 3, 4, 6 or 8, even more especially 3, 4, 6 or 8.
  • the collimator may e.g. have a rectangular cross-section, a hexagonal cross-section, or an octagonal cross-section.
  • bars in adjacent layers may be configured rotated relative to each other along an optical axis of the active collimator system, wherein the rotation is 360/n, wherein n is (thus) e.g. selected from 2, 3, 4, 6, 8, 10, 12 or 24, especially 3, 4, 6, 8, 10, 12 or 24, more especially 3, 4, 6, 8, 10, or 12, even more especially 4, 6 or 8
  • the active collimator system also comprises a light guide.
  • the light guide is configured to channel scintillation photons from a scintillator bar towards individual photosensors in the photosensor unit.
  • the light guide may especially be configured to reduce position-dependent differences in light collection efficiency.
  • the active collimator system may also contain a plurality of light guides.
  • the light guide is positioned in between the scintillator bar and the photosensor unit.
  • Each light guide is functionally coupled with the scintillator bar, especially with a plurality of scintillator bars, such as with 1-5,000 scintillator bars, such as at least 4, like at least 16, such as at least 64.
  • the light guide is functionally coupled with the photosensor unit.
  • the light guide may in embodiments have the shape of a plate and may be optically coupled, such as physically coupled to a side of the collimator. Hence, the (length and width) dimensions of the light guide(s) may essentially be the same as the of the (respective) collimator side(s).
  • the photosensor unit is configured to receive and count scintillation photons emitted by the scintillator bar.
  • the photosensor unit may comprise a photosensor array.
  • the photosensor unit comprises one or more photosensors, especially a plurality of photosensors, such as 1-5,000,000,000 photosensors, such as at least 4, like at least 16, such as at least 64.
  • the photosensors may comprise photomultiplier tubes.
  • the photosensors may comprise digital photon counters.
  • the photosensors may comprise photodetectors, or hybrid photodetectors, or silicon-based Geiger-mode photodetectors.
  • the photosensors may comprise silicon-based Photomultipliers (SiPMs), more especially the photosensors may comprise digital SiPMs.
  • the photosensor units comprise silicon photomultipliers (SiPM).
  • SiPMs are a class of silicon single photon sensors based on single-photon avalanche diodes (SPAD).
  • the SiPMs could be digital silicon photomultipliers (dSiPM) and/or digital photon counters (DPC).
  • dSiPM and DPC, etc. may actually refer to the same class of devices, viz. SiPMs with integrated digital data acquisition, processing, and readout circuits.
  • the photosensor units are especially end-mounted to the (sides of the) scintillator bars, especially with light guides in between.
  • the photosensors or photosensor units are configured at ends of the scintillator bars.
  • Each bar may have (two) scintillator bar ends. These ends define the length of the scintillator bars.
  • the bars may essentially have the same length or there may be bars with different length.
  • at least one end of a plurality of bars, more especially essentially all bars are directed to photosensor units.
  • at least a part of the total number of bars have bar ends that are both directed to photosensor units.
  • the scintillator bars have polygonal cross-sections (along a length axis of the scintillator bars) selected from the group of triangular cross- sections and rectangular cross-sections (such as essentially square cross-sections). Further, the scintillator bars have scintillator bar faces defining the (coded) collimator aperture. Not all bar faces may be used to define the collimator aperture.
  • the collimator system comprises a plurality of bars, of which a subset, also of a plurality of bars, define (with their bar faces) the aperture(s). Especially, essentially all bars together may define the collimator.
  • the active collimator system further comprises one or more light guides configured downstream of the scintillator bars and upstream of the photosensor units, wherein one or more of the photosensor units comprise one or more photosensors, wherein the one or more of the photosensor units are functionally coupled to a respective light guide, wherein the respective light guide is configured to distribute the scintillation photons from the scintillator bars to the one or more photosensors in the respective photosensor unit.
  • the scintillator bar may thus have ends at which photosensor units may be arranged, which are both considered to be arranged downstream of the bar, as the photons are generated within the bar and may propagate to the bar end and be detected by the photosensor unit(s).
  • the current invention also provides a nuclear imaging system.
  • the nuclear imaging system comprises the active collimator system as defined herein, the nuclear imaging system further comprising a gamma ray detector, configured downstream of the active collimator system, wherein the gamma ray detector is configured to detect gamma rays that have passed through the coded collimator aperture of the active collimator system.
  • the gamma ray detector especially its detector surface, may intercept the optical axis of the collimator system.
  • the nuclear imaging comprises a plurality of active collimator systems and (associated) gamma ray detectors.
  • Nuclear imaging systems are especially specialized imaging systems for nuclear medicine. These systems are configured to locate radionuclide markers within a subject by detecting the radiation that these markers emit.
  • the subject and the nuclear imaging system may move with respect to one another.
  • the nuclear imaging system may comprise a moving gantry, especially wherein the moving gantry moves around the subject.
  • the nuclear imaging system may comprise a moving subject area.
  • the nuclear imaging system comprises one or more gamma ray detectors. These gamma ray detectors may be assembled in a partial or whole ring around the subject. Instead of the term“subject area” also the terms“staging area” or “sensing area” may be applied.
  • a gamma ray detector is a device that detects gamma rays.
  • the gamma ray detector may comprise a position-resolving gamma ray detector, i.e., a gamma ray detector that is configured to determine the origin location of an incident gamma ray.
  • the gamma ray detector may comprise a position- and-energy-resolving gamma ray detector, i.e., a gamma ray detector that is configured to determine the origin location and the energy of an incident gamma ray.
  • the gamma ray detector may comprise one or more scintillator crystals and/or scintillator ceramics, especially one or more scintillator crystals, one or more light guides, and one or more photosensor units.
  • the scintillator crystals and/or scintillator ceramics may of course be bars.
  • the gamma ray detectors can e.g. measure one or more of the location, the time and the deposited energy of any gamma ray interaction.
  • the gamma ray detector may include essentially the same type of scintillator bars, photosensor units and light guides as the active collimator system; however, these are configured without aperture.
  • the nuclear imaging system may comprise a gamma ray detector configured downstream of the active collimator system, wherein the gamma ray detector is configured to detect gamma rays that have passed through the coded collimator aperture of the active collimator system, and wherein the gamma ray detector has a substantially continuous detection surface, i.e. the (downstream) gamma ray detector is devoid of apertures.
  • the gamma ray detector may especially be non-coded.
  • the gamma ray detector surface may be non-coded. Therefore, especially in embodiments a conventional gamma ray detector may be applied, of which the entire detection surface can be used to detect gamma rays that passed the coded collimator aperture.
  • the gamma ray detector especially comprises a gamma camera.
  • Gamma cameras are known in the art.
  • the gamma camera comprises a large scintillation crystal, especially a Nal(Tl) scintillation crystal, a light guide, and an array of photomultiplier tubes, and may further comprise a plurality of analog-to-digital converts and a collimator.
  • the scintillation crystal is configured to absorb gamma rays and scintillate, thereby releasing scintillation photons.
  • the light guide is functionally coupled to the scintillation crystal and is configured to distribute the scintillation photons to one or more of the photomultiplier tubes in the array.
  • the photomultiplier tubes are configured to detect scintillation photons and provide an output signal, especially an analog output signal.
  • the analog-to-digital converters are functionally coupled to the photomultiplier tubes and convert the analog output signal to an electronic output signal, especially to a digital output signal.
  • the electronic output signal is further processes by a device, especially a computer, functionally coupled to the gamma camera.
  • the collimator may be configured upstream of the scintillation crystal, and is configured to selectively absorb incoming gamma rays based on their incidence angle and location.
  • the gamma camera is configured to position-and-energy-resolve incoming gamma rays.
  • the downstream gamma ray detector is configured to detect gamma rays that have passed the active collimator.
  • the nuclear imaging system may especially include a plurality of active collimator systems, each functionally coupled to one or more gamma ray detectors.
  • the combination of collimator system and gamma ray detector may form a unit that may be configured at least partly rotatable around a sensing stage.
  • the sensing stage may e.g. be configured to host a human.
  • the nuclear imaging system may comprise or may be functionally coupled to a control system, configured to control the nuclear imaging system.
  • the control system may be configured to control the combination(s) of collimator system and gamma ray detector(s).
  • the control system may be configured to analyze the data generated by the gamma ray detector(s).
  • the nuclear imaging system may comprise one or more of the anatomical imaging systems and the functional imaging systems, such as imaging systems for positron emission tomography (PET), single photon emission computed tomography (SPECT), computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, tomosynthesis, optical fluorescence, magnetic particle imaging (MPI), electroencephalography (EEG), Electrocardiography (ECG) etc.
  • the nuclear imaging system may comprise one or more of a positron emission tomography (PET) imaging system, a single photon emission computed tomography (SPECT) imaging system, a computed tomography (CT) imaging system, and a magnetic resonance imaging (MRI) imaging system.
  • PET positron emission tomography
  • SPECT single photon emission computed tomography
  • CT computed tomography
  • MRI magnetic resonance imaging
  • the nuclear imaging system comprises a PET-SPECT detector system with active collimation. This may e.g. allow measuring gamma-rays emitted from multiple SPECT and PET molecular vectors simultaneously.
  • the nuclear imaging system comprises a PET-SPECT-CT imaging system or PET- SPECT-MRI imaging system capable of measuring multiple molecular vectors simultaneously, whilst integrated into an X-ray CT or MRI gantry to obtain anatomical information, and yield an entirely new dimension of physiological information for clinicians to use in diagnosis and treatment.
  • An example of this would be the measurement of multiple biological processes simultaneous, such as metabolism, hypoxia, apoptosis, DNA damage repair, etc., to determine regions of radio resistance within tumors during radiotherapy treatment.
  • the imaging system may in embodiments further optionally comprise one or more other anatomical and/or functional imaging systems (or functionally be coupled to such systems).
  • Fig. 1A schematically depicts a cross-section of a parallel-hole collimator
  • Fig. 1B schematically depicts a cross-section of a pinhole collimator
  • Fig. 1C schematically depicts cross-sections of both a converging collimator and a diverging collimator
  • Fig. 2A schematically depicts a perspective view of an active collimator system having light guides and a coded collimator aperture, wherein the coded collimator aperture has a pinhole shape
  • Fig. 2B schematically depicts the front view an active collimator system having a coded collimator aperture, wherein the coded collimator aperture has a pinhole shape
  • Fig. 2C schematically depicts the front (or top) view an active collimator system having light guides and a coded collimator aperture, wherein the coded collimator aperture has a parallel-hole shape
  • Fig. 2D schematically depicts the side view of an active collimator system having light guides and a coded collimator aperture, wherein the coded collimator aperture has a parallel- hole shape
  • Fig. 3 schematically depicts a cross-section of a nuclear imaging system comprising the active collimator
  • Fig. 4 schematically depicts a nuclear imaging system comprising the active collimator.
  • Figs 1A-1C schematically depict cross-sections (along an optical axis O) of a non-limiting number of embodiments of shapes of collimator apertures 201 of collimators 50.
  • Fig. 1 A schematically depicts a cross-section of a collimator 50 having a collimator aperture 201 with a parallel-hole shape 116.
  • the collimator has a collimator aperture 201 and comprises collimator material 200.
  • the collimator 50 further has two outer planes 203, 204 at opposite ends of the collimator material 200 and perpendicular to an optical axis O, wherein the outer planes 203, 204 are separated by a distance Ll parallel to the optical axis O.
  • the collimator aperture 201 has a parallel-hole shape 116 and comprises a plurality of parallel apertures (or openings). Especially, the parallel apertures may be parallel to the optical axis O. These parallel apertures are separated by collimator material 200.
  • Fig. lB schematically depicts a cross-section of a collimator 50 having a collimator aperture 201 with a pinhole shape 117.
  • the collimator 50 has a collimator aperture 201 and comprises collimator material 200.
  • the collimator 50 further has two outer planes 203, 204 at opposite ends of the collimator material 200 and perpendicular to an optical axis O, wherein the outer planes 203, 204 are separated by a distance Ll parallel to the optical axis O.
  • the collimator aperture 201 has a pinhole shape 117.
  • the collimator aperture 201 is shaped as an hourglass along the optical axis O.
  • the collimator aperture 201 may also be shaped as a partial hourglass. Especially, the collimator aperture 201 may be cone-shaped, such as the hourglass shape as depicted. More especially, each cross- section of the collimator aperture 201 perpendicular to the optical axis O is a circle.
  • Fig. 1C schematically depicts a cross-section of an embodiment of a collimator 50 having a collimator aperture 201 with either a converging shape 118 or a diverging shape 119 (dependent upon the view direction along an optical axis O).
  • the converging shape 118 and the diverging shape 119 may be mirror images of each other.
  • the collimator 50 has a collimator aperture 201 and comprises collimator material 200.
  • the collimator 50 further has two outer planes 203, 204 at opposite ends of the collimator material 200 and perpendicular to the optical axis O, wherein the outer planes 203, 204 are separated by a distance Ll parallel to the optical axis O.
  • the collimator aperture 201 comprises a plurality of non-parallel apertures having a downstream aperture end and an upstream aperture end.
  • the upstream aperture ends and the downstream aperture ends of the non-parallel apertures coincide with the outer planes 203, 204, wherein ‘upstream’ and ‘downstream’ indicate a relative position to a gamma ray emitting source along the optical axis outside of the collimator 50.
  • the non-parallel apertures are configured having an aperture angle b with the optical axis O.
  • the non-parallel apertures are configured such that the aperture angle b increases with increasing distance to the optical axis O.
  • two adjacent non-parallel apertures have angles b, b 1; b 2 , wherein the aperture closer to the optical axis O has angle bi and the aperture further from the optical axis has angle b 2 and bi ⁇ b 2.
  • the collimator aperture 201 having a converging shape 118 is configured such that the distance of the upstream aperture end to the optical axis O is smaller than the distance of the downstream aperture end to the optical axis O.
  • the collimator aperture 201 having a diverging shape 119 is configured such that the distance of the upstream aperture end to the optical axis O is larger than the distance of the downstream aperture end to the optical axis O.
  • Embodiments also include collimators 50 having collimator apertures 201 shaped according to two or more of the parallel-hole shape 116, the pinhole shape 117, the converging shape 118, and the diverging shape 119.
  • collimators 50 having a collimator aperture shaped according to one or more of a fan beam collimator, a multi-pinhole collimator, or a slit-slat collimator.
  • Fig. 2A schematically depicts an embodiment of the active collimator system 100.
  • the active collimator system 100 comprises scintillator bars 110, light guides 120, and photosensor units 130.
  • the scintillator bars 110 have scintillator bar faces 114 defining a coded collimator aperture 111.
  • the scintillator bars 110 have opposite scintillator bar ends 112, 1 13 and are configured in a layered stack 150.
  • the layered stack 150 comprises scintillator bar layers 151 wherein scintillator bars 110 are configured in a parallel orientation. Adjacent scintillator bars 1 10 within any one of the scintillator bar layers 151 may touch each other.
  • adjacent scintillator bars 1 10 within any one of the scintillator bar layers 151 may not touch each other, e.g., to define (part of) the coded collimator aperture 11 1.
  • the succession of touching and non-touching adjacent scintillator bars 1 10 in any one of the layers 151 follows a pattern (T x N y T z ) n , wherein x equals z, the sum of x, y, z is constant, and n equals 1, and wherein x, y, z vary along the optical axis O.
  • Scintillator bars 110 in two adjacent scintillator bar layers 151A, 151B may be configured in a non-parallel orientation. Especially, scintillator bars 110 in two adjacent scintillator bar layers 151A, 151B are not placed in parallel orientations. More especially, the scintillator bars 1 10 in two adjacent scintillator bar layers 151A, 151B may be configured having an angle between the respective orientations, wherein the degree of the angle is a proper divisor of 180°. Most especially, the degree of the angle is 90°, 60°, or 45° degrees. In this embodiment, the degree of the angle is 90°. In this schematically depicted embodiments, k, as defined above, is 4, and n, as defined above is also 4.
  • the coded collimator aperture 11 1 approximates the shape of a pinhole collimator aperture 117.
  • the coded collimator aperture 111 approximates the shape of an hourglass along the optical axis (O).
  • the layers are especially defined perpendicular to the optical axis O.
  • the layers may also be seen as virtual layers.
  • collimator 50 is seen with two side faces and on one of the outer planes.
  • the outer plane is configured perpendicular to the optical axis O; the side faces are here configured parallel to the optical axis O.
  • Fig. 2B schematically depicts another embodiment of an active collimator system 100.
  • the active collimator system 100 comprises scintillator bars 110, and photosensor units 130.
  • the scintillator bars 1 10 have opposite scintillator bar ends 1 12, 113 and scintillator bar faces 1 14 defining the collimator aperture, here especially a coded collimator aperture 1 1 1.
  • the coded collimator aperture 111 has - in this schematically depicted embodiment - a pinhole collimator shape 1 17, approximating the shape of a pinhole collimator.
  • the coded collimator aperture 111 is shaped as an hourglass along the optical axis O.
  • the view of the coded collimator aperture 11 1 is a top view of a cross-section of the coded collimator aperture 111 in Fig. 2A (hence, the coded collimator aperture 111 is not depicted in perspective despite the overall perspective drawing in Fig. 2B).
  • the photosensor units 130 are configured end-mounted to both scintillator bar ends 112, 113 of the scintillator bars 110.
  • the scintillator bars are functionally coupled to the photosensor units 130 end-mounted to the scintillator bar ends 112, 113.
  • the incoming gamma rays 160 either pass through the coded collimator aperture 111 or are absorbed by any one of the scintillator bars 110.
  • the scintillator bar 110 After absorption of an incoming gamma ray 160, the scintillator bar 110 emits scintillation photons 161.
  • the photosensor units 130 are configured to detect scintillation photons 161 emitted by functionally coupled scintillator bars 110.
  • the photosensor units 130 are configured end-mounted to the scintillator bar ends 112.
  • the scintillator bar ends 113 may have end-mounted photosensor units 130.
  • the light guides are configured between a plurality of scintillator bars 110 and any one of the photosensor units 130.
  • the light guides 120 are functionally coupled to the plurality of scintillator bars 110, and to the respective photosensor unit 130.
  • the scintillator bars 110 are configured to absorb incoming gamma rays 160 and scintillate, thereby releasing scintillation photons 161.
  • the light guides 120 are configured to distribute scintillation photons 161 from the coupled plurality of scintillator bars (110) to the coupled respective photosensor unit 130.
  • the light guides 120 are configured to distribute scintillation photons 161 to one or more photosensors 131 in the photosensor unit 130.
  • Fig. 2C schematically depicts a top view of a cross-section perpendicular to an optical axis O of an embodiment of the active collimator system 100.
  • the active collimator system 100 comprises scintillator bars 110 and four photosensor units 130.
  • the active collimator system 100 further comprises four light guides 120.
  • the active collimator system 100 further comprises metal inserts 115.
  • the scintillator bars 110 have scintillator bar ends 112, 113 and scintillator bar faces 114, wherein the scintillator bar faces 114 define a coded collimator aperture 111.
  • the coded collimator aperture 111 has the shape of a parallel-hole collimator aperture 116. Especially, the coded collimator aperture 111 has parallel holes.
  • the metal inserts 115 may further define the coded collimator aperture 111.
  • the metal inserts 115 may have an identical cross-section along the optical axis O.
  • the metal inserts 115 may have a variable cross-section along the optical axis O.
  • the metal inserts 1 15 may all have the same shape. Especially, the metal inserts 115 may also have different shapes.
  • the metal inserts 115 may further define the coded collimator aperture 111 along the optical axis O by narrowing, widening, focusing and/or slanting each aperture in the coded collimator aperture 111.
  • the metal inserts may cover a scintillator bar face 114. Especially, the metal inserts may partially cover a scintillator bar face 114.
  • Each of the light guides 120 is configured end-mounted to scintillator bar ends 112, 113 of a plurality of scintillator bars 110, and is configured to be fimctionally coupled with the respective plurality of scintillator bars 110.
  • Each of the photosensor units 130 is configured end-mounted to one of the light guides 120, and is configured to be functionally coupled with the respective light guide 120.
  • Fig. 2D schematically depicts another embodiment of the active collimator system 100.
  • the active collimator system 100 comprises scintillator bars 110, light guides 120, and photosensor units 130.
  • the scintillator bars have scintillator bar ends 1 12, 113 and scintillator bar faces 114.
  • the scintillator bars 110 are arranged in scintillator bar layers 151 along an optical axis O. Adjacent scintillator bars 110 within any one of the scintillator bar layers 151 may touch each other.
  • adjacent scintillator bars 110 within any one of the scintillator bar layers 151 may not touch each other, e.g., to define (part of) the coded collimator aperture 111.
  • the succession of touching and non-touching adjacent scintillator bars 110 in any one of the layers 151 partially follows a pattern (N y T z ) n N, wherein y equals 1, z equals 1 and n equals 7.
  • the scintillator bar layers 151 are configured as stacked layers 150.
  • the scintillator bar 110 in any one of the scintillator bar layers 151 have a parallel orientation.
  • the scintillator bars 110 in two adjacent scintillator bar layers 151 A, 151B may be rotated relative to each other along an optical axis O.
  • the scintillator bar faces 114 define a coded collimator aperture 111.
  • the coded collimator aperture 111 has the shape of a parallel-hole collimator aperture 116 (which would be visible when the collimator would be seen from the top along the optical axis O, see Fig. 2C).
  • Each of the light guides is end-mounted to scintillator bar ends 112 of a plurality of scintillator bars 110, and is functionally coupled to the plurality of scintillator bars 110.
  • Each of the photosensor units 130 comprises a plurality of photosensors 131.
  • the photosensor unit 130 may be end-mounted and is functionally coupled to one of the light guides 120.
  • the photosensor unit 130 may be in physical contact with the light guide 120; the light guide 120 may be in physical contact with the scintillator bars 110 (at one side of the collimator 50).
  • the scintillator bars 110 are configured to absorb incident gamma rays 160 and scintillate, thereby releasing scintillation photons 161.
  • the light guides 120 are configured to distribute the scintillation photons 161 from the functionally coupled plurality of scintillator bars 110 to one or more photosensors 131 in the photosensor unit 130.
  • Fig. 3 schematically depicts a cross-section of an embodiment of a nuclear imaging system 1000 comprising the active collimator system 100 in operation.
  • the nuclear imaging system 1000 comprises a staging area 170, active collimator systems 100, and gamma ray detectors 140.
  • a human or animal, or other subject may be at the staging area.
  • the object under investigation may include positron emitting radionuclide markers 172 and/or gamma ray emitting radionuclide markers 173.
  • the staging area 170 may comprise locally accumulated positron emitting radionuclide markers 172 and locally accumulated gamma ray emitting radionuclide markers 173.
  • the positron emitting radionuclide markers 172 emit positrons.
  • the positrons travel a small distance from the positron emitting radionuclide marker 172 before encountering an electron and undergoing a positron annihilation event, resulting in the emission of two paired gamma rays 162 in roughly opposite directions.
  • the gamma ray emitting radionuclide markers 173 emit unpaired gamma rays 163.
  • Each active collimator system 100 is configured to either reject or accept incoming gamma rays 160, 162, 163 based on their incidence angle and location. Rejected gamma ray 160, 162, 163 are absorbed, detected and measured by the active collimator system 100. Accepted gamma rays 160, 162, 163 pass through the active collimator system 100.
  • Each of the gamma ray detectors 140 is configured downstream of one or more active collimator systems 100 to detect and measure gamma rays 160, 162, 163 that pass through the one or more active collimator systems 100. It is clear to a person skilled in the art that some gamma rays may penetrate the active collimator system 100.
  • the gamma ray detectors 140 are configured to detect and measure gamma rays 160, 162, 163 that penetrate the active collimator system 100.
  • the gamma ray detectors 140 are configured to detect and measure paired gamma rays 162 that penetrate the active collimator system.
  • the rays herein are only indicated by way of example.
  • active collimation may allow for one or more imaging modalities to be integrated into a single imaging bore to measure gamma-rays emitted from multiple SPECT and PET molecular vectors simultaneously whilst using X- ray/MR functionality, and/or one or more other functionalities, to obtain anatomical information of the subject.
  • the nuclear imaging system 1000 may further include or be functionally coupled to one or more of an optical imaging system, an ultrasound imaging system, an ECG imaging system, an EEG imaging system, and a magnetic particle imaging system, etc.
  • active collimation may be coupled with essentially any imaging modality that can obtain additional anatomical (i.e. ultrasound, tomosynthesis, etc.) or functional (optical fluorescence, magnetic particle) information.
  • Fig. 4 schematically depicts an embodiment of a nuclear imaging system 1000 comprising the active collimator system 100.
  • the nuclear imaging system 1000 comprises a staging area 170, a plurality of active collimator systems 100, and a plurality of gamma ray detectors 140.
  • the active collimator systems 100 are configured to at least partially encircle the staging area 170. Especially, the active collimator systems 100 fully encircle the staging area 170.
  • the gamma ray detectors 140 are configured downstream of the active collimator systems 100.
  • the staging area 170 may comprise a subject, wherein the subject intermittently emits gamma rays towards the active collimator systems 100 and the downstream gamma ray detectors 140.
  • the active collimator systems 100 are configured to selectively absorb, detect and measure incoming gamma rays based on their incidence angle and location.
  • the gamma ray detectors are configured to absorb, detect and measure the gamma rays that pass through the active collimator system 100.
  • upstream and“downstream” relate to an arrangement of items or features relative to the propagation of rays from a ray generating means wherein relative to a first position within a ray from the ray generating means, a second position in the ray closer to the ray generating means is“upstream”, and a third position within the ray further away from the ray generating means is “downstream”.
  • the term“substantially” may also include embodiments with“entirely”,“completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed.
  • the term“substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.
  • the term“comprise” includes also embodiments wherein the term “comprises” means“consists of 7
  • the term“and/or” especially relates to one or more of the items mentioned before and after“and/or”.
  • phrase“item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2.
  • the term “comprising” may in an embodiment refer to “consisting of' but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species”.
  • the invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.
  • the invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

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Abstract

La présente invention concerne un système de collimateur actif (100) ayant une ouverture de collimateur codée (111), le système de collimateur actif (100) comprenant des barres de scintillateur (110) et des unités de photodétecteur (130), les barres de scintillateur (110) étant configurées pour absorber les rayons gamma entrants (160) et scintiller, émettant ainsi des photons de scintillation (161), les barres de scintillateur (110) étant en outre conçues pour définir l'ouverture de collimateur codée (111), les unités de photodétecteur (130) étant conçues pour détecter les photons de scintillation (161), et les unités de photodétecteur (130) étant dirigées vers les extrémités de barre de scintillateur (112) des barres de scintillateur (110).
PCT/NL2018/050893 2018-01-05 2018-12-31 Collimateur actif pour émission de positrons et tomodensitométrie à émission de photons uniques WO2019135676A1 (fr)

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NL2020237A NL2020237B1 (en) 2018-01-05 2018-01-05 Active collimator for positron emission and single photon emission computed tomography

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WO2022037473A1 (fr) * 2020-08-19 2022-02-24 清华大学 Unité de détection et de collimation, appareil de détection et système d'imagerie temp

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