Hamamatsu-photonics K.k.

Hamamatsu Photonics Kabushiki Kaisha

National Institutes for Quantum and Radiological Science and Technology

National Institute of Radiological Sicences

Eiichi Tanaka

Takaji Yamashita

Taiga Yamaya

Hiroyuki Okada

Mitsuo Watanabe

Hiroshi Uchida

Tomohide Omura

Takayuki Obata

Nakahiro Satoh

Hideaki Tashima

Fumihiko Nishikido

Keiji Shimizu

Tatsuro Hayashi

Mikio Suga

Kazuyuki Saito

An inclined PET device is provided in which the cut plane of a detector ring upon which a plurality of PET detectors are disposed is inclined so that it does not intersect perpendicularly with the long axis of a bed that carries a subject to be examined and in which an open space that passes through the bed in a direction perpendicular to the long axis thereof is formed, in order to enable access to the subject to be examined. The PET detectors are disposed and stacked in a direction parallel to the long axis of the bed. Thereby, the number of PET detectors is reduced and device cost is reduced, while the detector ring as well as the device can be miniaturized. At the same time, the open space that passes through the bed in a direction perpendicular to the long axis can be preserved.

Inclined pet device and pet combined device

In the integrated PET/MRI scanner provided with an RF coil for MRI and a plurality of PET detectors in the measuring port of the MRI scanner, the PET detectors are disposed with spaces therebetween and at least the transmitting coil elements of the RF coil for MRI are disposed between adjacent PET detectors. Here, the PET detectors are disposed in the circumferential direction of the measuring port with spaces therebetween and the transmitting coil elements are disposed in the axial direction of the measuring port. Alternatively, at least some of the PET detectors are disposed in the axial direction of the measuring port with spaces therebetween and the transmitting coil elements are disposed between adjacent PET detectors. The PET detectors can be DOI-type detectors capable of detecting position in the depth direction.

Integrated PET/MRI scanner

A PET apparatus is provided, which ensures excellent quantitativeness by properly correcting the influence of scattered radiation while improving the resolution of a reconstructed image and keeping good photon pair detection sensitivity. A determining sectiondetermines whether a straight line connecting the light-receiving surfacesof a pair of photon detectorswhich have simultaneously detected a photon pair crosses any one of slice collimators. When it is determined that the straight line crosses none of the slice collimators, the corresponding coincidence counting information is accumulated by a first coincidence counting information storage sectionto generate a signal sinogram. When it is determined that the straight line crosses one of the slice collimators, the corresponding coincidence counting information is accumulated by a second coincidence counting information storage sectionto generate a scatter sinogram. An image reconstructing sectioncorrects the influence of scattered components on the signal sinogram on the basis of the scattered sinogram, and reconstructs an image on the basis of the corrected signal sinogram.

PET device and image generating method for pet device

A rotating ceptorprovided inside a detector portionincludes nine shield plates Sto Sdisposed in parallel to each other in between adjacent detector rings R, acts as a collimator, and allows only those photon pairs that have traveled approximately parallel to a slice plane to be made incident upon photon detectors D located behind the rotating ceptor. Each of the shield plates S is not formed annularly, and provided near the measurement field of viewof part of N photon detectors D that constitute each of the detector rings R. The rotating ceptoris rotatable about its center axis. Each of the shield plates S is provided with bar-shaped radiation source insertion holesandfor allowing a bar-shaped positron emission radiation sourceto be inserted therein and supported thereby.

Pet device

The energy E of a signal pulse P inputted to an energy measurement apparatusfor measurement, and corresponding to the total integrated intensity, is calculated in an energy calculation unitfrom the integrated signal intensity Q acquired by a gate integrator, and from the pulse interval T measured by a pulse interval measurement unit. At this time, pileup correction is performed using at least one of the integrated signal intensity or the energy, and the pulse interval of the signal pulse inputted prior to the signal pulse for measurement. By this means, the correct energy E, with the effect of pileup eliminated, can be determined with good precision. Hence a method and apparatus for energy measurement are realized which enable correct and precise measurement of the energy of individual signal pulses, even when the pulse interval between signal pulses is short.

Method and apparatus for measuring signal pulse energy

A PET apparatus includes a detecting unit; slice septa for transmitting therethrough flying photons nearly perpendicular to the center axis; a slice septa position determining section for determining whether or not the slice septa exist in the measurement space side of at least one of the pair of photon detectors; a two-dimensional projection image storage section for storing coincidence-counting information of the photon pair obtained by the pair of photon detectors; a three-dimensional projection data storage section for storing coincidence counting information obtained by the pair of photon detectors; and an image reconstructing section for reconstruction an image indicative of a spatial distribution of a frequency at which photon pairs are emitted in the measurement space.

Positron emission tomography apparatus

Two .gamma.-rays accompanying position annihilation are incident into .gamma.-ray detectors in detector arrays set with a measured object inbetween. Electric pulse signals output from the .gamma.-ray detectors are supplied to an annihilation presuming unit, which obtains a presumable event of positron annihilation by the coincidence counting conditions and which notifies an image reconstructing unit of annihilation occurrence notification and information of detectors. Electric pulse signals output from the .gamma.-ray detectors are supplied to a time-of-flight difference measuring unit, which measures a difference of detection time between the detectors and notifies the image reconstructing unit of it. The image reconstructing unit obtains a presumable annihilation position based on the received information and stores it. A tomographic image of a specific portion is obtained by an algorithm for substantially compensating measurement errors, for example by the iterative process with the stored information.

Positron imaging apparatus

A positron CT scanner includes a plurality of detectors arranged in a generally cylindrical multi-layers of rings, and slice septa for restricting visual fields of the detectors so that the visual fields intersect a set axis. An interval of the slice septa is substantially corresponds to a plural number of detector cells each of which can determine positions of .gamma. rays incident in the direction of the set axis. The slice septa are movable relatively to the detector cells in the direction of the set axis during a .gamma. ray counting operation.

Positron computed tomography scanner

A radiation detector basically comprises a scintillator, a light guide for introducing scintillation light, and a photodetector for detecting the scintillation light. A light output portion of the scintillator is wedge-shaped, and a light input portion of the light guide is V-shaped in section so as to receive the wedge-shaped light output portion of the scintillator. With this arrangement, light reflection at the interfaces of the scintillator and light guide is reduced, resulting in an improvement of transmission efficiency of light.

Radiation detector

An ionization chamber can stably measure a weak ionizing radiation with high sensitivity. The ionization chamber comprises an electrically conductive charge collecting electrode having a magnetic substance or a permanent magnet; an electromagnet for positioning the charge collecting electrode in non-contact with the other part of the ionization chamber; a position sensor for detecting the position of the charge collecting electrode; a circuit for feedback-controlling the magnetic force of the electromagnet to maintain the charge collecting electrode at the substantially same position; and ionization current detecting circuit for detecting an ionization current collected at the charge collecting electrode by ionization due to radiation applied to the ionization chamber.

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Hamamatsu, Japan

Eiichi Tanaka