WO2015189467A1 - A detector for positron emission tomography - Google Patents

A detector for positron emission tomography Download PDF

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Publication number
WO2015189467A1
WO2015189467A1 PCT/FI2015/050392 FI2015050392W WO2015189467A1 WO 2015189467 A1 WO2015189467 A1 WO 2015189467A1 FI 2015050392 W FI2015050392 W FI 2015050392W WO 2015189467 A1 WO2015189467 A1 WO 2015189467A1
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WO
WIPO (PCT)
Prior art keywords
scintillating
bars
wavelength shifting
wavelength
photons
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Application number
PCT/FI2015/050392
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French (fr)
Inventor
Ulla Ruotsalainen
Defne US
Original Assignee
Tty-Säätiö
Tampereen Yliopisto
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Application filed by Tty-Säätiö, Tampereen Yliopisto filed Critical Tty-Säätiö
Publication of WO2015189467A1 publication Critical patent/WO2015189467A1/en

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    • 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
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
    • G01T1/2914—Measurement of spatial distribution of radiation
    • G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T5/00—Recording of movements or tracks of particles; Processing or analysis of such tracks
    • G01T5/08—Scintillation chambers

Definitions

  • the invention relates generally to positron emission tomography "PET”. More particularly, the invention relates to a detector for positron emission tomography and to a method for producing information for the purpose of positron emission tomography.
  • the positron emission tomography "PET” is a functional medical imaging technique for producing three- or two-dimensional images with the aid of which functional processes in a body of an individual can be studied.
  • a system for the positron emission tomography is arranged to detect gamma-photons emitted indirectly by positron-emitting radionuclides of radiotracer material which is introduced into the body under study. The images of the radiotracer concentration within the body are then constructed with computer analysis.
  • the axial positron emission tomography "AX-PET” is a geometrical concept for the positron emission tomography.
  • the axial positron emission tomography is based on elongated scintillating crystals, i.e. scintillating bars, and wavelength shifting "WLS" strips that are positioned transversely with respect to the scintillating bars.
  • the scintillating bars emit photons belonging to a first wavelength band in response to interaction with gamma-photons received from an object of the positron emission tomography, and the wavelength shifting strips emit photons belonging to a second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band.
  • the scintillating bars may comprise for example Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having the peak of the emission spectrum at 420 nm when interacting with gamma-photons.
  • the wavelength shifting strips may comprise for example plastic doped with suitable light fluorescent material.
  • the wavelength shifting strips can be made of e.g. EJ-280-10x from Eljen Technology, Texas, USA.
  • the scintillating bars and the wavelength shifting strips are individually readout with the aid of photo-detectors which may be e.g. fast Geiger-mode avalanche photo-diodes.
  • the coordinates of a source point of a gamma-photon are constructed on the basis of output signals of the photo-detectors.
  • each scintillating bar there is a photo-detector at only one end of each scintillating bar and the other end is coated with reflective material for reflecting photons towards the end comprising the photo-detector.
  • the scintillating bars are positioned so that there are gaps between adjacent ones of the scintillating bars, and correspondingly the wavelength shifting strips are positioned so that there are gaps between adjacent ones of the wavelength shifting strips.
  • the above-mentioned gaps are needed in many cases for being able to arrange the photo-detectors at the ends of the scintillating bars and at the ends of the wavelength shifting strips.
  • the scintillating bars must not touch each other, i.e. cannot be wall-to-wall, because total internal reflections have to take place on the side-walls of the scintillating bars and photons emitted by one of the scintillating bars must not transfer to another of the scintillating bars.
  • the wavelength shifting strips must not touch each other, i.e.
  • the wavelength shifting strips cannot be wall-to-wall, because total internal reflections have to take place on the side-walls of the wavelength shifting strips and photons emitted by one of the wavelength shifting strips must not transfer to another of the wavelength shifting strips.
  • especially the gaps between adjacent ones of the wavelength shifting strips should be as small as possible in order to achieve a sufficient detection sensitivity i.e. in order to avoid a situation where too big a portion of photons emitted by the scintillating bars flee through the gaps between the adjacent ones of the wavelength shifting strips.
  • a detector for positron emission tomography comprises one or more detector layers each of which comprises:
  • the scintillating bars constitute a scintillating layer so that there are gaps between the scintillating bars.
  • the first wavelength shifting strips constitute a wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer.
  • the second wavelength shifting strips constitute another wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer.
  • the two wavelength shifting layers on both sides of the scintillating layer improve the detection sensitivity because a greater portion of the photons emitted by the scintillating bars can be received by the wavelength shifting strips.
  • a detector according to an exemplifying and non-limiting embodiment of the invention there are two or more detector layers of the kind described above and the detector layers are stacked on each other in the direction perpendicular to the scintillating layers of the detector layers so that the scintillating bars of a first one of the detector layers overlap with the gaps between the scintillating bars of a second one of the detector layers when seen from the direction perpendicular to the scintillating layers of the detector layers.
  • a method according to the invention comprises:
  • first wavelength shifting strips constituting a wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, and
  • the second wavelength shifting strips constituting another wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer.
  • the amounts of the photons emitted by individual ones of the scintillating bars represent a first part of the information for the positron emission tomography and the amounts of the photons emitted by individual ones of the first and second wavelength shifting strips represent a second part of the information for the positron emission tomography.
  • figures 1 a, 1 b, and 1 c illustrate a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography
  • PET positron emission tomography
  • figures 2a, 2b, and 2c illustrate a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography
  • figure 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for producing information for the purpose of positron emission tomography.
  • Figure 1 a shows a side-view of a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography "PET".
  • Figure 1 b shows a top-view of the detector, and figure 1 c shows an end-view of the detector.
  • the exemplifying detector illustrated in figures 1 a-1 c comprises one detector layer 101 and thus the detector can be used for detecting the x- and y- coordinates of a source point of a gamma-photon emitted by an object of the positron emission tomography, e.g. a part of a human body carrying radiotracer material .
  • the source point is typically a point where a positron is annihilated and gamma-photons are released as a result of the annihilation.
  • the above-mentioned x- and y-coordinates are coordinates of a coordinate system 199.
  • the detector layer 101 comprises scintillating bars 105 for emitting photons belonging to a first wavelength band in response to interaction with gamma- photons received from the object of the positron emission tomography.
  • the scintillating bars 105 may comprise for example Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having the peak of the emission spectrum at 420 nm when interacting with 51 1 keV gamma-photons.
  • the detector layer 101 comprises first wavelength shifting "WLS" strips 106 for emitting photons belonging to a second wavelength band in response to receiving, from the scintillating bars 105, photons belonging to the first wavelength band. Furthermore, the detector layer 101 comprises second wavelength shifting strips 107 for emitting photons belonging to the second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band.
  • the first and second wavelength shifting strips 106 and 107 may comprise for example plastic doped with suitable light fluorescent material.
  • the wavelength shifting strips 106 and 107 can be e.g. green-emitting EJ-280 plastic or red-emitting EJ-284 plastic from Eljen Technology, Texas, USA.
  • the length of the scintillating bars 105 in the y-direction can be for example but not necessarily from 10 cm to 20 cm, e.g. 15 cm.
  • the width of the the scintillating bars 105 in the x-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm, and the thickness of the scintillating bars 105 in the z-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm.
  • the length of the wavelength shifting "WLS" strips 106 and 107 in the x-direction can be for example but not necessarily from 4.0 cm to 6.0 cm, e.g. 5.0 cm.
  • the width of the WLS strips in the y-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm, and the thickness of the WLS strips in the z-direction can be for example but not necessarily from 0.7 mm to 1 .1 mm, e.g. 0.9 mm.
  • the scintillating bars 105 constitute a scintillating layer so that there are gaps between adjacent ones of the scintillating bars.
  • the scintillating layer is parallel with the xy-plane of the coordinate system 199.
  • the width of the gaps between adjacent ones of the scintillating bars in the x-direction can be for example but not necessarily from 0.3 mm to 1 .0 mm, e.g. 0.5 mm.
  • the first wavelength shifting strips 106 constitute a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between adjacent ones of the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars 105 when seen from a direction perpendicular to the scintillating layer, i.e. from a direction parallel with the z-axis of the coordinate system 199.
  • the first wavelength shifting layer is parallel with the xy-plane of the coordinate system 199.
  • the first wavelength shifting strips 106 are advantageously positioned transversely with respect to the scintillating bars 105 so that there is a right-angle between the longitudinal direction of the scintillating bars 105 and the longitudinal direction of the first wavelength shifting strips 106 as illustrated in figure 1 b.
  • the second wavelength shifting strips 107 constitute a second wavelength shifting layer on a second side of the scintillating layer so that that the second wavelength shifting strips 107 are crossing the scintillating bars 105 and overlapping with the gaps between the first wavelength shifting strips 106 when seen from a direction perpendicular to the scintillating layer, i.e. from a direction parallel with the z-axis of the coordinate system 199.
  • the second wavelength shifting layer is parallel with the xy-plane of the coordinate system 199.
  • the second wavelength shifting strips 107 are advantageously positioned transversely with respect to the scintillating bars 105 so that there is a right-angle between the longitudinal direction of the scintillating bars 105 and the longitudinal direction of the second wavelength shifting strips 107.
  • the width of the gaps between adjacent ones of the wavelength shifting strips in the y-direction is at most the width of the wavelength shifting strips in the y- direction so as achieve the situation where the second wavelength shifting strips 107 overlap with the gaps between adjacent ones of the first wavelength shifting strips 106 and correspondingly the first wavelength shifting strips 106 overlap with the gaps between adjacent ones of the second wavelength shifting strips 107 when seen from a direction parallel with the z-axis of the coordinate system 199.
  • the two wavelength shifting layers on both sides of the scintillating layer improve the detection sensitivity because a greater portion of the photons emitted by the scintillating bars 105 can be received by the wavelength shifting strips.
  • a detector comprises first photo-detectors for receiving, from the scintillating bars 106, photons belonging to the first wavelength band and for generating first signals indicative of the amount of photons received from each of the scintillating bars.
  • the first signals are depicted with arrows 1 16 in figure 1 b.
  • the x-coordinate of a source point of a gamma-photon emitted by an object of the positron emission tomography can be computed on the basis of the first signals 1 16.
  • One of the first photo-detectors is denoted with a reference number 108 in figures 1 a and 1 b.
  • the first photo-detectors can be e.g.
  • G- APD fast Geiger-mode avalanche photo-diodes
  • the detector is coupled to an external device comprising photo-detectors which are pressed against the appropriate ends of the scintillating bars 106 when the detector and the device are interconnected.
  • a first end of each of the scintillating bars 106 is coated with reflective material, e.g. aluminum, for reflecting photons from the first end of the scintillating bar under consideration towards the second end of the scintillating bar.
  • the reflective material at the first end of one of the scintillating bars 106 is denoted with a reference number 109 in figures 1 a and 1 b.
  • the above-mentioned first photo-detectors are located at the second ends of the scintillating bars.
  • a detector comprises second photo-detectors for receiving, from each of the first wavelength shifting strips 106 and from each of the second wavelength shifting strips 107, photons belonging to the second wavelength band and for generating second signals indicative of the amount of photons received from each of the wavelength shifting strips.
  • the second signals are depicted with arrows 1 17 in figure 1 b.
  • the y-coordinate of a source point of the gamma-photon emitted by the object of the positron emission tomography can be computed on the basis of the second signals 1 17.
  • One of the second photo-detectors is denoted with a reference number 1 10 in figures 1 b and 1 c.
  • the second photo-detectors can be e.g. fast Geiger-mode avalanche photo-diodes. It is also possible that the detector is coupled to an external device comprising photo-detectors which are pressed against the appropriate ends of the wavelength shifting strips when the detector and the device are interconnected.
  • a first end of each of the wavelength shifting strips 106 and 107 is coated with reflective material, e.g. aluminum, for reflecting photons from the first end of the wavelength shifting strip under consideration towards the second end of the wavelength shifting strip.
  • the reflective material at the first end of one of the wavelength shifting strips is denoted with a reference number 1 1 1 in figures 1 b and 1 c.
  • the above-mentioned second photo-detectors are located at the second ends of the wavelength shifting strips. In principle, it is also possible to have photo-detectors at both ends of the of the wavelength shifting strips but it is more cost effective to have photo-detectors at only one ends of the wavelength shifting strips and reflective material at the other ends of the wavelength shifting strips.
  • the detector illustrated in figures 1 a-1 c comprises a mechanical structure comprising support portions 1 12, 1 13, and 1 14 and 1 15 for mechanically supporting the scintillating bars 106.
  • the support portions are shaped to reduce areas of the support portions abutting on surfaces of the scintillating bars so as to minimize the disturbance to the optical operation of the scintillating bars.
  • Figure 1 a shows a section view of a part of the mechanical structure comprising the above- mentioned support portions 1 12-1 15.
  • the mechanical structure is not shown in figures 1 b and 1 c.
  • the mechanical structure comprises advantageously similar support portions for mechanically supporting and the first and second wavelength shifting strips 106 and 107.
  • the mechanical support structure can be for example a light impervious casing of the detector.
  • Figure 2a shows a side-view of a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography "PET".
  • Figure 2b shows a top-view of the detector, and figure 2c shows an end-view of the detector.
  • the exemplifying detector illustrated in figures 2a-2c comprises four detector layers 201 , 202, 203, and 204. Each of the detector layers can be such as the detector layer 101 described above and illustrated in figures 1 a-1 c.
  • the detector layers 201 -204 are stacked on each other in the direction perpendicular to the scintillating layers constituted by the scintillating bars of the detector layers, i.e. in the z-direction of a coordinate system 299.
  • the detector can be used for detecting the x- and z-coordinates of a source point of a gamma-photon emitted by an object of the PET on the basis of signals 216 produced by first photo-detectors connected to ends of the scintillating bars.
  • the detector can be used for detecting the y-coordinate of the source point on the basis of signals 217 produced by second photo-detectors connected to ends of the wavelength shifting strips of the detector layers 201 -204.
  • the above-mentioned x-, y- and z-coordinates are coordinates of the coordinate system 299.
  • the detector comprises advantageously sheets of light impervious material between adjacent ones of the detector layers 201 -204. One of the sheets is denoted with a reference number 218 in figures 2a and 2c.
  • the detector layers 201 -204 are stacked on each other so that the scintillating bars of first ones of the detector layers overlap with the gaps between the scintillating bars of second ones of the detector layers when seen from the direction perpendicular to the scintillating layers of the detector layers, i.e. from a direction parallel with the z-axis of the coordinate system 299.
  • This mechanical arrangement improves the detection sensitivity because a greater portion of the gamma-photons emitted by the object of the PET can be received by the scintillating bars.
  • a detector of the kind described above and illustrated in figures 2a-2c can be constructed also by stacking detector modules on each other where each detector module comprises a detector such as the detector illustrated in figures 1 a-1 c.
  • FIG. 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for producing information for the purpose of positron emission tomography "PET".
  • the method comprises the following actions:
  • - action 301 receiving gamma-photons, from an object of the positron emission tomography, by scintillating bars which emit photons belonging to a first wavelength band in response to interaction between the scintillating bars and the gamma-photons, the scintillating bars constituting a scintillating layer so that there are gaps between the scintillating bars,
  • - action 302 receiving first ones of the photons emitted by the scintillating bars by first wavelength shifting "WLS" strips emitting photons belonging to a second wavelength band, the first wavelength shifting strips constituting a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, and
  • - action 303 receiving second ones of the photons emitted by the scintillating bars by second wavelength shifting strips emitting photons belonging to the second wavelength band, the second wavelength shifting strips constituting a second wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer.
  • the amounts of the photons emitted by individual ones of the scintillating bars represent a first part of the information for the positron emission tomography, and the amounts of the photons emitted by individual ones of the first and second wavelength shifting strips represent a second part of the information for the positron emission tomography.
  • the photons belonging to the first wavelength band are received from the scintillating bars with first photo-detectors which generate first signals indicative of the amount of the photons received from each of the scintillating bars.
  • the photons belonging to the first wavelength band are reflected from first ends of the scintillating bars towards second ends of the scintillating bars with reflective material, and the first photo-detectors are located at the second ends of the scintillating bars.
  • the photons belonging to the second wavelength band are received from each of the first wavelength shifting strips and from each of the second wavelength shifting strips with second photo-detectors which generate second signals indicative of the amount of the photons received from each of the wavelength shifting strips.
  • the photons belonging to the second wavelength band are reflected from first ends of the first and second wavelength shifting strips towards second ends of the first and second wavelength shifting strips with reflective material, and the second photo-detectors are located at the second ends of the first and second wavelength shifting strips.
  • the scintillating bars and the first and second wavelength shifting strips are mechanically supported with support portions which have been shaped so that areas of the support portions abutting on surfaces of the scintillating bars and the first and second wavelength shifting strips are reduced.
  • the scintillating bars comprise Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having a peak of an emission spectrum at 420 nm when interacting with gamma-photons.
  • LYSO Cerium-doped Lutetium Yttrium Orthosilicate
  • the first and second wavelength shifting strips comprise plastic doped with light fluorescent material.
  • the non-limiting, specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims.
  • the number of detector layers, the number of scintillating bars in each detector layer, and the number of wavelength shifting strips in each detector layer can vary between detectors according to different embodiments of the invention.

Abstract

A detector for positron emission tomography PET comprises scintillating bars (105) emitting photons on a first wavelength band when receiving gamma-photons from an object of the PET, and first and second wavelength shifting strips (106, 07) placed transversely with respect to the scintillating bars and emitting photons on a second wavelength band when receiving photons emitted by the scintillating bars. The scintillating bars constitute a scintillating layer, the first wavelength shifting strips constitute a wavelength shifting layer on a first side of the scintillating layer, and the second wavelength shifting strips constitute another wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips overlap with the gaps between the first wavelength shifting strips, and vice versa, when seen from a direction perpendicular to the scintillating layer. The two wavelength shifting layers on both sides of the scintillating layer improve the detection sensitivity.

Description

A detector for Positron Emission Tomography
Field of the invention
The invention relates generally to positron emission tomography "PET". More particularly, the invention relates to a detector for positron emission tomography and to a method for producing information for the purpose of positron emission tomography.
Background
The positron emission tomography "PET" is a functional medical imaging technique for producing three- or two-dimensional images with the aid of which functional processes in a body of an individual can be studied. A system for the positron emission tomography is arranged to detect gamma-photons emitted indirectly by positron-emitting radionuclides of radiotracer material which is introduced into the body under study. The images of the radiotracer concentration within the body are then constructed with computer analysis.
The axial positron emission tomography "AX-PET" is a geometrical concept for the positron emission tomography. The axial positron emission tomography is based on elongated scintillating crystals, i.e. scintillating bars, and wavelength shifting "WLS" strips that are positioned transversely with respect to the scintillating bars. The scintillating bars emit photons belonging to a first wavelength band in response to interaction with gamma-photons received from an object of the positron emission tomography, and the wavelength shifting strips emit photons belonging to a second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band. The scintillating bars may comprise for example Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having the peak of the emission spectrum at 420 nm when interacting with gamma-photons. The wavelength shifting strips may comprise for example plastic doped with suitable light fluorescent material. The wavelength shifting strips can be made of e.g. EJ-280-10x from Eljen Technology, Texas, USA. The scintillating bars and the wavelength shifting strips are individually readout with the aid of photo-detectors which may be e.g. fast Geiger-mode avalanche photo-diodes. The coordinates of a source point of a gamma-photon are constructed on the basis of output signals of the photo-detectors. Typically, there is a photo-detector at only one end of each scintillating bar and the other end is coated with reflective material for reflecting photons towards the end comprising the photo-detector. Correspondingly, there is typically a photo-detector at only one end of each wavelength shifting strip and the other end is coated with reflective material for reflecting photons towards the end comprising the photo-detector. The scintillating bars are positioned so that there are gaps between adjacent ones of the scintillating bars, and correspondingly the wavelength shifting strips are positioned so that there are gaps between adjacent ones of the wavelength shifting strips. The above-mentioned gaps are needed in many cases for being able to arrange the photo-detectors at the ends of the scintillating bars and at the ends of the wavelength shifting strips. Furthermore, the scintillating bars must not touch each other, i.e. cannot be wall-to-wall, because total internal reflections have to take place on the side-walls of the scintillating bars and photons emitted by one of the scintillating bars must not transfer to another of the scintillating bars. Correspondingly, the wavelength shifting strips must not touch each other, i.e. cannot be wall-to-wall, because total internal reflections have to take place on the side-walls of the wavelength shifting strips and photons emitted by one of the wavelength shifting strips must not transfer to another of the wavelength shifting strips. On the other hand, especially the gaps between adjacent ones of the wavelength shifting strips should be as small as possible in order to achieve a sufficient detection sensitivity i.e. in order to avoid a situation where too big a portion of photons emitted by the scintillating bars flee through the gaps between the adjacent ones of the wavelength shifting strips.
Summary
The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying and non-limiting embodiments of the invention. In accordance with the invention, there is provided a new detector for positron emission tomography "PET". A detector according to the invention comprises one or more detector layers each of which comprises:
- scintillating bars for emitting photons belonging to a first wavelength band in response to interaction with gamma-photons received from an object of the positron emission tomography,
- first wavelength shifting "WLS" strips for emitting photons belonging to a second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band, and
- second wavelength shifting strips for emitting photons belonging to the second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band.
The scintillating bars constitute a scintillating layer so that there are gaps between the scintillating bars. The first wavelength shifting strips constitute a wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer. The second wavelength shifting strips constitute another wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer.
The two wavelength shifting layers on both sides of the scintillating layer improve the detection sensitivity because a greater portion of the photons emitted by the scintillating bars can be received by the wavelength shifting strips. In a detector according to an exemplifying and non-limiting embodiment of the invention, there are two or more detector layers of the kind described above and the detector layers are stacked on each other in the direction perpendicular to the scintillating layers of the detector layers so that the scintillating bars of a first one of the detector layers overlap with the gaps between the scintillating bars of a second one of the detector layers when seen from the direction perpendicular to the scintillating layers of the detector layers.
In accordance with the invention, there is provided also a new method for producing information for the purpose of positron emission tomography "PET". A method according to the invention comprises:
- receiving gamma-photons, from an object of the positron emission tomography, by scintillating bars which emit photons belonging to a first wavelength band in response to interaction between the scintillating bars and the gamma-photons, the scintillating bars constituting a scintillating layer so that there are gaps between the scintillating bars,
- receiving first ones of the photons emitted by the scintillating bars by first wavelength shifting "WLS" strips emitting photons belonging to a second wavelength band, the first wavelength shifting strips constituting a wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, and
- receiving second ones of the photons emitted by the scintillating bars by second wavelength shifting strips emitting photons belonging to the second wavelength band, the second wavelength shifting strips constituting another wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer. The amounts of the photons emitted by individual ones of the scintillating bars represent a first part of the information for the positron emission tomography and the amounts of the photons emitted by individual ones of the first and second wavelength shifting strips represent a second part of the information for the positron emission tomography.
A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.
Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in connection with the accompanying drawings.
The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.
Brief description of figures Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which: figures 1 a, 1 b, and 1 c illustrate a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography "PET", figures 2a, 2b, and 2c illustrate a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography, and figure 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for producing information for the purpose of positron emission tomography.
Description of exemplifying and non-limiting embodiments Figure 1 a shows a side-view of a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography "PET". Figure 1 b shows a top-view of the detector, and figure 1 c shows an end-view of the detector. The exemplifying detector illustrated in figures 1 a-1 c comprises one detector layer 101 and thus the detector can be used for detecting the x- and y- coordinates of a source point of a gamma-photon emitted by an object of the positron emission tomography, e.g. a part of a human body carrying radiotracer material . The source point is typically a point where a positron is annihilated and gamma-photons are released as a result of the annihilation. The above-mentioned x- and y-coordinates are coordinates of a coordinate system 199. The detector layer 101 comprises scintillating bars 105 for emitting photons belonging to a first wavelength band in response to interaction with gamma- photons received from the object of the positron emission tomography. The scintillating bars 105 may comprise for example Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having the peak of the emission spectrum at 420 nm when interacting with 51 1 keV gamma-photons. The detector layer 101 comprises first wavelength shifting "WLS" strips 106 for emitting photons belonging to a second wavelength band in response to receiving, from the scintillating bars 105, photons belonging to the first wavelength band. Furthermore, the detector layer 101 comprises second wavelength shifting strips 107 for emitting photons belonging to the second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band. The first and second wavelength shifting strips 106 and 107 may comprise for example plastic doped with suitable light fluorescent material. The wavelength shifting strips 106 and 107 can be e.g. green-emitting EJ-280 plastic or red-emitting EJ-284 plastic from Eljen Technology, Texas, USA. The length of the scintillating bars 105 in the y-direction can be for example but not necessarily from 10 cm to 20 cm, e.g. 15 cm. The width of the the scintillating bars 105 in the x-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm, and the thickness of the scintillating bars 105 in the z-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm. The length of the wavelength shifting "WLS" strips 106 and 107 in the x-direction can be for example but not necessarily from 4.0 cm to 6.0 cm, e.g. 5.0 cm. The width of the WLS strips in the y-direction can be for example but not necessarily from 2.0 mm to 4.0 mm, e.g. 3.0 mm, and the thickness of the WLS strips in the z-direction can be for example but not necessarily from 0.7 mm to 1 .1 mm, e.g. 0.9 mm. As illustrated in figures 1 b and 1 c, the scintillating bars 105 constitute a scintillating layer so that there are gaps between adjacent ones of the scintillating bars. The scintillating layer is parallel with the xy-plane of the coordinate system 199. The width of the gaps between adjacent ones of the scintillating bars in the x-direction can be for example but not necessarily from 0.3 mm to 1 .0 mm, e.g. 0.5 mm. As illustrated in figures 1 a and 1 b, the first wavelength shifting strips 106 constitute a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between adjacent ones of the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars 105 when seen from a direction perpendicular to the scintillating layer, i.e. from a direction parallel with the z-axis of the coordinate system 199. The first wavelength shifting layer is parallel with the xy-plane of the coordinate system 199. The first wavelength shifting strips 106 are advantageously positioned transversely with respect to the scintillating bars 105 so that there is a right-angle between the longitudinal direction of the scintillating bars 105 and the longitudinal direction of the first wavelength shifting strips 106 as illustrated in figure 1 b. The second wavelength shifting strips 107 constitute a second wavelength shifting layer on a second side of the scintillating layer so that that the second wavelength shifting strips 107 are crossing the scintillating bars 105 and overlapping with the gaps between the first wavelength shifting strips 106 when seen from a direction perpendicular to the scintillating layer, i.e. from a direction parallel with the z-axis of the coordinate system 199. The second wavelength shifting layer is parallel with the xy-plane of the coordinate system 199. The second wavelength shifting strips 107 are advantageously positioned transversely with respect to the scintillating bars 105 so that there is a right-angle between the longitudinal direction of the scintillating bars 105 and the longitudinal direction of the second wavelength shifting strips 107. The width of the gaps between adjacent ones of the wavelength shifting strips in the y-direction is at most the width of the wavelength shifting strips in the y- direction so as achieve the situation where the second wavelength shifting strips 107 overlap with the gaps between adjacent ones of the first wavelength shifting strips 106 and correspondingly the first wavelength shifting strips 106 overlap with the gaps between adjacent ones of the second wavelength shifting strips 107 when seen from a direction parallel with the z-axis of the coordinate system 199. The two wavelength shifting layers on both sides of the scintillating layer improve the detection sensitivity because a greater portion of the photons emitted by the scintillating bars 105 can be received by the wavelength shifting strips.
A detector according to an exemplifying and non-limiting embodiment of the invention comprises first photo-detectors for receiving, from the scintillating bars 106, photons belonging to the first wavelength band and for generating first signals indicative of the amount of photons received from each of the scintillating bars. The first signals are depicted with arrows 1 16 in figure 1 b. The x-coordinate of a source point of a gamma-photon emitted by an object of the positron emission tomography can be computed on the basis of the first signals 1 16. One of the first photo-detectors is denoted with a reference number 108 in figures 1 a and 1 b. The first photo-detectors can be e.g. fast Geiger-mode avalanche photo-diodes "G- APD". It is also possible that the detector is coupled to an external device comprising photo-detectors which are pressed against the appropriate ends of the scintillating bars 106 when the detector and the device are interconnected.
In the exemplifying case illustrated in figures 1 a-1 c, a first end of each of the scintillating bars 106 is coated with reflective material, e.g. aluminum, for reflecting photons from the first end of the scintillating bar under consideration towards the second end of the scintillating bar. The reflective material at the first end of one of the scintillating bars 106 is denoted with a reference number 109 in figures 1 a and 1 b. The above-mentioned first photo-detectors are located at the second ends of the scintillating bars. In principle, it is also possible to have photo-detectors at both ends of the of the scintillating bars but it is more cost effective to have photo- detectors at only one ends of the scintillating bars and reflective material at the other ends of the scintillating bars.
A detector according to an exemplifying and non-limiting embodiment of the invention comprises second photo-detectors for receiving, from each of the first wavelength shifting strips 106 and from each of the second wavelength shifting strips 107, photons belonging to the second wavelength band and for generating second signals indicative of the amount of photons received from each of the wavelength shifting strips. The second signals are depicted with arrows 1 17 in figure 1 b. The y-coordinate of a source point of the gamma-photon emitted by the object of the positron emission tomography can be computed on the basis of the second signals 1 17. One of the second photo-detectors is denoted with a reference number 1 10 in figures 1 b and 1 c. The second photo-detectors can be e.g. fast Geiger-mode avalanche photo-diodes. It is also possible that the detector is coupled to an external device comprising photo-detectors which are pressed against the appropriate ends of the wavelength shifting strips when the detector and the device are interconnected.
In the exemplifying case illustrated in figures 1 a-1 c, a first end of each of the wavelength shifting strips 106 and 107 is coated with reflective material, e.g. aluminum, for reflecting photons from the first end of the wavelength shifting strip under consideration towards the second end of the wavelength shifting strip. The reflective material at the first end of one of the wavelength shifting strips is denoted with a reference number 1 1 1 in figures 1 b and 1 c. The above-mentioned second photo-detectors are located at the second ends of the wavelength shifting strips. In principle, it is also possible to have photo-detectors at both ends of the of the wavelength shifting strips but it is more cost effective to have photo-detectors at only one ends of the wavelength shifting strips and reflective material at the other ends of the wavelength shifting strips.
The detector illustrated in figures 1 a-1 c comprises a mechanical structure comprising support portions 1 12, 1 13, and 1 14 and 1 15 for mechanically supporting the scintillating bars 106. The support portions are shaped to reduce areas of the support portions abutting on surfaces of the scintillating bars so as to minimize the disturbance to the optical operation of the scintillating bars. Figure 1 a shows a section view of a part of the mechanical structure comprising the above- mentioned support portions 1 12-1 15. The mechanical structure is not shown in figures 1 b and 1 c. The mechanical structure comprises advantageously similar support portions for mechanically supporting and the first and second wavelength shifting strips 106 and 107. The mechanical support structure can be for example a light impervious casing of the detector.
Figure 2a shows a side-view of a detector according to an exemplifying and non- limiting embodiment of the invention for positron emission tomography "PET". Figure 2b shows a top-view of the detector, and figure 2c shows an end-view of the detector. The exemplifying detector illustrated in figures 2a-2c comprises four detector layers 201 , 202, 203, and 204. Each of the detector layers can be such as the detector layer 101 described above and illustrated in figures 1 a-1 c. The detector layers 201 -204 are stacked on each other in the direction perpendicular to the scintillating layers constituted by the scintillating bars of the detector layers, i.e. in the z-direction of a coordinate system 299. The detector can be used for detecting the x- and z-coordinates of a source point of a gamma-photon emitted by an object of the PET on the basis of signals 216 produced by first photo-detectors connected to ends of the scintillating bars. The detector can be used for detecting the y-coordinate of the source point on the basis of signals 217 produced by second photo-detectors connected to ends of the wavelength shifting strips of the detector layers 201 -204. The above-mentioned x-, y- and z-coordinates are coordinates of the coordinate system 299. The detector comprises advantageously sheets of light impervious material between adjacent ones of the detector layers 201 -204. One of the sheets is denoted with a reference number 218 in figures 2a and 2c.
As illustrated in figure 2c, the detector layers 201 -204 are stacked on each other so that the scintillating bars of first ones of the detector layers overlap with the gaps between the scintillating bars of second ones of the detector layers when seen from the direction perpendicular to the scintillating layers of the detector layers, i.e. from a direction parallel with the z-axis of the coordinate system 299. This mechanical arrangement improves the detection sensitivity because a greater portion of the gamma-photons emitted by the object of the PET can be received by the scintillating bars.
It is worth noting that a detector of the kind described above and illustrated in figures 2a-2c can be constructed also by stacking detector modules on each other where each detector module comprises a detector such as the detector illustrated in figures 1 a-1 c.
Figure 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for producing information for the purpose of positron emission tomography "PET". The method comprises the following actions:
- action 301 : receiving gamma-photons, from an object of the positron emission tomography, by scintillating bars which emit photons belonging to a first wavelength band in response to interaction between the scintillating bars and the gamma-photons, the scintillating bars constituting a scintillating layer so that there are gaps between the scintillating bars,
- action 302: receiving first ones of the photons emitted by the scintillating bars by first wavelength shifting "WLS" strips emitting photons belonging to a second wavelength band, the first wavelength shifting strips constituting a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, and
- action 303: receiving second ones of the photons emitted by the scintillating bars by second wavelength shifting strips emitting photons belonging to the second wavelength band, the second wavelength shifting strips constituting a second wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer. The amounts of the photons emitted by individual ones of the scintillating bars represent a first part of the information for the positron emission tomography, and the amounts of the photons emitted by individual ones of the first and second wavelength shifting strips represent a second part of the information for the positron emission tomography.
In a method according to an exemplifying and non-limiting embodiment of the invention, the photons belonging to the first wavelength band are received from the scintillating bars with first photo-detectors which generate first signals indicative of the amount of the photons received from each of the scintillating bars. In a method according to an exemplifying and non-limiting embodiment of the invention, the photons belonging to the first wavelength band are reflected from first ends of the scintillating bars towards second ends of the scintillating bars with reflective material, and the first photo-detectors are located at the second ends of the scintillating bars. In a method according to an exemplifying and non-limiting embodiment of the invention, the photons belonging to the second wavelength band are received from each of the first wavelength shifting strips and from each of the second wavelength shifting strips with second photo-detectors which generate second signals indicative of the amount of the photons received from each of the wavelength shifting strips.
In a method according to an exemplifying and non-limiting embodiment of the invention, the photons belonging to the second wavelength band are reflected from first ends of the first and second wavelength shifting strips towards second ends of the first and second wavelength shifting strips with reflective material, and the second photo-detectors are located at the second ends of the first and second wavelength shifting strips.
In a method according to an exemplifying and non-limiting embodiment of the invention, the scintillating bars and the first and second wavelength shifting strips are mechanically supported with support portions which have been shaped so that areas of the support portions abutting on surfaces of the scintillating bars and the first and second wavelength shifting strips are reduced.
In a method according to an exemplifying and non-limiting embodiment of the invention, the scintillating bars comprise Cerium-doped Lutetium Yttrium Orthosilicate "LYSO" having a peak of an emission spectrum at 420 nm when interacting with gamma-photons.
In a method according to an exemplifying and non-limiting embodiment of the invention, the first and second wavelength shifting strips comprise plastic doped with light fluorescent material. The non-limiting, specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. For example, the number of detector layers, the number of scintillating bars in each detector layer, and the number of wavelength shifting strips in each detector layer can vary between detectors according to different embodiments of the invention.

Claims

What is claimed is:
1 . A detector for positron emission tomography, the detector comprising one or more detector layers (101 , 201 -204) each of which comprises:
- scintillating bars (105) for emitting photons belonging to a first wavelength band in response to interaction with gamma-photons received from an object of the positron emission tomography, and
- first wavelength shifting strips (106) for emitting photons belonging to a second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band, wherein the scintillating bars constitute a scintillating layer so that there are gaps between the scintillating bars, and the first wavelength shifting strips constitute a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, characterized in that the detector layer further comprises second wavelength shifting strips (107) for emitting photons belonging to the second wavelength band in response to receiving, from the scintillating bars, photons belonging to the first wavelength band, and positioned to constitute a second wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer.
2. A detector according to claim 1 , wherein detector comprises first photo- detectors (108) for receiving, from the scintillating bars, photons belonging to the first wavelength band and for generating first signals indicative of amount of the photons received from each of the scintillating bars.
3. A detector according to claim 2, wherein first ends of the scintillating bars are coated with reflective material (109) for reflecting photons belonging to the first wavelength band from the first ends of the scintillating bars towards second ends of the scintillating bars, and the first photo-detectors are located at the second ends of the scintillating bars.
4. A detector according to any of claims 1 -3, wherein detector comprises second photo-detectors (1 10) for receiving, from each of the first wavelength shifting strips and from each of the second wavelength shifting strips, photons belonging to the second wavelength band and for generating second signals indicative of amount of the photons received from each of the first wavelength shifting strips and from each of the second wavelength shifting strips.
5. A detector according to claim 4, wherein first ends of the first and second wavelength shifting strips are coated with reflective material (1 1 1 ) for reflecting photons belonging to the second wavelength band from the first ends of the first and second wavelength shifting strips towards second ends of the first and second wavelength shifting strips, and the second photo-detectors are located at the second ends of the first and second wavelength shifting strips.
6. A detector according to any of claims 1 -5, wherein the detector comprises a mechanical structure comprising support portions (1 12-1 15) for mechanically supporting the scintillating bars and the first and second wavelength shifting strips, the support portions being shaped to reduce areas of the support portions abutting on surfaces of the scintillating bars and the first and second wavelength shifting strips.
7. A detector according to any of claims 1 -6, wherein a first one (201 , 203) of the detector layers and a second one (202, 204) of the detector layers are stacked on each other in the direction perpendicular to the scintillating layers of the detector layers so that the scintillating bars of the first one of the detector layers overlap with gaps between the scintillating bars of the second one of the detector layers when seen from the direction perpendicular to the scintillating layers of the detector layers.
8. A detector according to any of claims 1 -7, wherein the scintillating bars comprise Cerium-doped Lutetium Yttrium Orthosilicate having a peak of an emission spectrum at 420 nm when receiving gamma-photons.
9. A detector according to any of claims 1 -8, wherein the first and second wavelength shifting strips comprise plastic doped with light fluorescent material.
10. A method for producing information for the purpose of positron emission tomography, the method comprising: - receiving (301 ) gamma-photons, from an object of the positron emission tomography, by scintillating bars which emit photons belonging to a first wavelength band in response to interaction between the scintillating bars and the gamma-photons, the scintillating bars constituting a scintillating layer so that there are gaps between the scintillating bars, and - receiving (302) first ones of the photons emitted by the scintillating bars by first wavelength shifting strips emitting photons belonging to a second wavelength band, the first wavelength shifting strips constituting a first wavelength shifting layer on a first side of the scintillating layer so that there are gaps between the first wavelength shifting strips and the first wavelength shifting strips are crossing the scintillating bars when seen from a direction perpendicular to the scintillating layer, wherein amounts of the photons emitted by individual ones of the scintillating bars represent a first part of the information for the positron emission tomography, characterized in that the method further comprises: - receiving (303) second ones of the photons emitted by the scintillating bars by second wavelength shifting strips emitting photons belonging to the second wavelength band, the second wavelength shifting strips constituting a second wavelength shifting layer on a second side of the scintillating layer so that the second wavelength shifting strips are crossing the scintillating bars and overlapping with the gaps between the first wavelength shifting strips when seen from the direction perpendicular to the scintillating layer, wherein amounts of the photons emitted by individual ones of the first and second wavelength shifting strips represent a second part of the information for the positron emission tomography.
PCT/FI2015/050392 2014-06-13 2015-06-08 A detector for positron emission tomography WO2015189467A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5103099A (en) * 1989-10-17 1992-04-07 Commissariat A L'energie Atomique Device for linear detection of radiation
US20020121604A1 (en) * 2000-08-29 2002-09-05 Masaki Katagiri Two-dimensional radiation and neutron image detectors
WO2006107727A2 (en) * 2005-04-01 2006-10-12 San Diego State University Foundation Edge-on sar scintillator devices and systems for enhanced spect, pet, and compton gamma cameras

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5103099A (en) * 1989-10-17 1992-04-07 Commissariat A L'energie Atomique Device for linear detection of radiation
US20020121604A1 (en) * 2000-08-29 2002-09-05 Masaki Katagiri Two-dimensional radiation and neutron image detectors
WO2006107727A2 (en) * 2005-04-01 2006-10-12 San Diego State University Foundation Edge-on sar scintillator devices and systems for enhanced spect, pet, and compton gamma cameras

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BOLLE E ET AL: "Development of a High Precision Axial 3-D PET for Brain Imaging", NUCLEAR PHYSICS B. PROCEEDINGS SUPPLEMENT, NORTH-HOLLAND, AMSTERDAM, NL, vol. 197, no. 1, 15 December 2009 (2009-12-15), pages 19 - 23, XP026917665, ISSN: 0920-5632, [retrieved on 20100221], DOI: 10.1016/J.NUCLPHYSBPS.2009.10.026 *
DEL GUERRA A ET AL: "<tex>$X$</tex></maths>-<maths><tex>$Y$</tex></maths> Position Readout of a YAP:Ce Crystal Matrix Using Wavelength-Shifting Fibers", IEEE TRANSACTIONS ON NUCLEAR SCIENCE, IEEE SERVICE CENTER, NEW YORK, NY, US, vol. 48, no. 4, 1 August 2001 (2001-08-01), XP011042084, ISSN: 0018-9499 *

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