JP2007271509A - Nuclear medicine diagnosis apparatus and diagnosis system used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear medicine diagnosis apparatus for improving a resolution in a nuclear medicine data, and a diagnosis system used for it. <P>SOLUTION: A rotating mechanism 30 rotates and drive a gamma-ray detector 3. A relative position between the gamma-ray detector 3 and a specimen M is changed by a half of an array pitch between detecting elements 3A. Since projection data are collected in a position of each detecting element 3A in the rotating gamma-ray detector 3, the gamma-ray detector 3 can detect and collect a plurality of projection data in proportion to a reduction in the array pitch to a half. The resolution in the projection data and a PET image such as a tomographic image can be improved without increasing the number of the detecting elements 3A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nuclear medicine diagnostic apparatus for obtaining nuclear medical data of a subject based on radiation generated from a subject to which a radiopharmaceutical is administered, and a diagnostic system used therefor, and particularly collects nuclear medical data. Regarding technology.

  As the above-described nuclear medicine diagnosis apparatus, that is, an ECT (Emission Computed Tomography) apparatus, a PET (Positron Emission Tomography) apparatus will be described as an example. The PET apparatus detects a plurality of γ-rays generated by annihilation of protons, that is, positrons, and reconstructs a tomographic image of a subject only when γ-rays are detected simultaneously by a plurality of detectors. It is configured.

  In this PET apparatus, after a radiopharmaceutical is administered to a subject, the process of drug accumulation in the target tissue is measured over time, whereby quantitative measurement of various biological functions is possible. Therefore, the tomographic image obtained by the PET apparatus has functional information.

  Specifically, taking a human body as an example of the subject, a radiopharmaceutical, which is an anti-annihilation γ-ray emitting substance that easily concentrates on a specific part or cell due to the biological function of the human body, is administered. A functional image of a living body can be taken by collecting projection data (also referred to as “emission data”), which is information released from a medicine, using a PET apparatus.

In the PET apparatus, a γ-ray detector for detecting γ-rays is composed of a plurality of detection elements, and each detection element is arranged in a ring shape so as to surround the body axis of the subject. Each detection element is composed of a scintillator block and a photomultiplier. In order to improve the resolution of nuclear medicine data (PET image) such as projection data and tomographic images and to determine a finer position, the number of detection elements is increased in the rotational direction (ie circumferential direction) around the body axis. Therefore, it is necessary to use a γ-ray detector composed of more detection elements (see, for example, Patent Document 1). By using such a γ-ray detector, it becomes possible to detect and collect more data in the circumferential direction by the γ-ray detector, and to improve the resolution.
Japanese Patent Laying-Open No. 2004-361302 (second page)

  However, such a γ-ray detector is expensive by the number of detection elements.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a nuclear medicine diagnostic apparatus capable of improving the resolution of nuclear medicine data and a diagnostic system used therefor.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is a nuclear medicine diagnostic apparatus that obtains nuclear medicine data of a subject based on radiation generated from the subject to which a radiopharmaceutical is administered, and includes a plurality of the respective radiations that detect the radiation. A detection means constituted by the detection elements, and a drive means for driving at least one of the detection means and the subject to change the relative position between the detection means and the subject within the range of the arrangement pitch between the detection elements. And collecting means for collecting nuclear medicine data at each relative position.

  [Operation / Effect] According to the first aspect of the present invention, the driving means drives at least one of the detection means constituted by a plurality of detection elements for detecting radiation and the subject as follows. That is, at least one of the detection means and the subject is driven to change the relative position between the detection means and the subject within the range of the arrangement pitch between the detection elements. The collection means collects nuclear medicine data at each relative position. Conventionally, nuclear medicine data was collected for each array pitch, but nuclear medicine data was collected within the array pitch range, so more nuclear medicine was saved by the amount narrowed within the array pitch range. Data can be detected by the detecting means and collected by the collecting means. As a result, the resolution of nuclear medicine data can be improved without increasing the number of detection elements.

  In the above-described invention, it is preferable that the driving unit drives at least one of the detection unit and the subject so as to change to the relative position at a pitch that is an integer of the arrangement pitch described above (the invention according to claim 2). . By driving at least one of the detection means and the subject at a pitch of an integer, conventional nuclear medicine data for each array pitch can be used as it is, and the collection of nuclear medicine data by the collection means It can be done easily.

  An example of the driving direction of at least one of the detection means by the driving means and the subject is the rotation direction (ie, circumferential direction) around the body axis of the subject. In other words, the drive means rotates at least one of the detection means and the subject around the body axis of the subject (the invention according to claim 3). By rotating at least one of the detection means and the subject around the body axis of the subject, it becomes possible to detect and collect nuclear medicine data in more rotational directions (circumferential directions).

  The drive means may drive at least one of the detection means and the subject intermittently so that the relative position changes at a predetermined pitch within the range of the arrangement pitch every predetermined time. The drive means continuously drives at least one of the detection means and the subject, and the collection means is driven until at least one of the detection means and the subject is driven at a predetermined pitch within the arrangement pitch range. Nuclear medical data may be collected at the relative position of each detection element with respect to the specimen (the invention according to claim 5), and the drive means detects at an arbitrary pitch within the range of the array pitch at an arbitrary timing. At least one of the means and the subject may be driven (the invention according to claim 6).

  Moreover, you may apply to the diagnostic system used for the nuclear medicine diagnostic apparatus based on the invention mentioned above. That is, this diagnostic system is configured to include a nuclear medicine diagnostic apparatus and an X-ray CT apparatus, and the nuclear medicine diagnostic apparatus is based on radiation generated from a subject to which a radiopharmaceutical is administered. Medical data is obtained, the X-ray CT apparatus obtains X-ray CT data based on the X-rays irradiated from the outside of the subject and transmitted through the subject, and the nuclear medicine diagnostic apparatus detects a plurality of radiations respectively. A detection means constituted by the detection elements, and a drive means for driving at least one of the detection means and the subject to change a relative position between the detection means and the subject within a range of an arrangement pitch between the detection elements; And a collecting means for collecting nuclear medicine data at each relative position (the invention according to claim 7).

  In the case of this system, in the X-ray CT apparatus, X-ray CT data is obtained based on X-rays irradiated from the outside of the subject and transmitted through the subject, and the nuclear medicine diagnostic apparatus obtains nuclear medicine data. The tomographic image in the X-ray CT data and the nuclear medicine diagnosis data may be superimposed and output, or the X-ray CT data is used as the absorption correction data to correct the absorption of the nuclear medicine data. You may go.

  According to the nuclear medicine diagnostic apparatus and the diagnostic system used therefor according to the present invention, at least one of the detection means and the subject is driven, and the detection means and the subject are relative to each other within the range of the arrangement pitch between the detection elements. Since the collecting means collects the nuclear medicine data at each relative position by changing the position, the detecting means detects and the collecting means collects more nuclear medicine data by the amount narrowed within the range of the arrangement pitch. be able to. As a result, the resolution of nuclear medicine data can be improved.

Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view and block diagram of a PET (Positron Emission Tomography) apparatus according to the first embodiment. In addition, this Example 1 including Example 2 mentioned later demonstrates taking a PET apparatus as an example as a nuclear medicine diagnostic apparatus.

  The PET apparatus according to the first embodiment includes a top plate 1 on which a subject M is placed as shown in FIG. The top plate 1 is configured to move up and down and translate along the body axis Z of the subject M. With this configuration, the subject M placed on the top 1 is scanned from the head to the abdomen and foot sequentially through the opening 2a of the gantry 2, which will be described later. Diagnostic data such as projection data and tomographic images are obtained. This diagnosis data is defined as “PET image” in this specification. This diagnostic data (PET image) corresponds to nuclear medicine data in the present invention.

  In addition to the top plate 1, the PET apparatus according to the first embodiment includes a gantry 2 having an opening 2a, a plurality of scintillator blocks 3a and a plurality of photomultipliers 3b arranged close to each other. Yes. As shown in FIG. 1B, the scintillator block 3 a and the photomultiplier 3 b are arranged in a ring shape so as to surround the body axis Z of the subject M, and are embedded in the gantry 2. The photomultiplier 3b is disposed outside the scintillator block 3a. As a specific arrangement of the scintillator block 3a, for example, two scintillator blocks 3a are arranged in a direction parallel to the body axis Z of the subject M, and many scintillator blocks 3a are arranged around the body axis Z of the subject M. Lined up forms are listed. The scintillator block 3a and the photomultiplier 3b constitute a γ-ray detector 3 for projection data (also referred to as “emission data”) to be described later. The γ-ray detector 3 corresponds to the detection means in this invention.

  Next, a schematic configuration of the γ-ray detector 3 will be described with reference to FIGS. FIG. 2 is a schematic front view of the rotation mechanism 30 that rotates the γ-ray detector 3 around the body axis Z of the subject M and the γ-ray detector 3, and FIG. 3 is a schematic front view of the γ-ray detector 3. It is. The scintillator block 3a and the photomultiplier 3b (see FIG. 1) constitute the detection element 3A as shown in FIG. 2 and FIG. 3, and each of the detection elements 3A arranged in a ring form γ rays. The detector 3 is configured. Each detection element 3A is arranged in a ring shape at a predetermined pitch.

  As shown in FIG. 2, the rotation mechanism 30 is a mechanism for rotating the γ-ray detector 3 around the body axis Z of the subject M and is embedded in the gantry 2. The rotation mechanism 30 includes a rotation motor 31 and a rotation belt 32. By driving the rotation motor 31 in the direction of the arrow in FIG. 2, the rotation belt 32 wound around the rotation motor 31 rotates in the same direction, and the rotation of the rotation belt 32 causes the entire γ-ray detector 3 to be examined. Rotate around body axis Z of M. Specific driving by the rotation mechanism 30 will be described later with reference to FIG. The detection element 3A corresponds to the detection element in the present invention, and the rotation mechanism 30 corresponds to the driving means in the present invention.

  The rotating mechanism 30 is not limited to the structure shown in FIG. For example, a mechanism that rotates the γ-ray detector 3 as a whole by providing a drive mechanism in the gantry 2 and rotating the gantry 2 itself may be used.

  Returning to the description of FIG. 1, the first embodiment includes a point source 4 and a γ-ray detector 5 for absorption correction data (also referred to as “transmission data”) described later. The γ-ray detector 5 for absorption correction data is composed of a scintillator block and a photomultiplier, like the γ-ray detector 3 for projection data. The dotted line source 4 is a radiation source that irradiates a radioactive drug to be administered to the subject M, that is, a radiation of the same kind as the radioisotope (RI) (in this embodiment, γ rays). It is installed. In the first embodiment, it is embedded in the gantry 2. The dotted line source 4 rotates around the body axis Z of the subject M.

  In addition, the PET apparatus according to the first embodiment includes a top board driving unit 6, a controller 7, an input unit 8, an output unit 9, a projection data deriving unit 10, an absorption correction data deriving unit 11, an absorption correcting unit 12, The configuration unit 13, the memory unit 14, and the rotation mechanism 30 described above are provided. The top plate driving unit 6 is a mechanism for driving the top plate 1 so as to perform the above-described movement, and is configured by a motor or the like not shown.

  The controller 7 comprehensively controls each part constituting the PET apparatus according to the first embodiment. The controller 7 includes a central processing unit (CPU).

  The input unit 8 sends data and commands input by the operator to the controller 7. The input unit 8 includes a pointing device represented by a mouse, a keyboard, a joystick, a trackball, a touch panel, and the like. The output unit 9 includes a display unit represented by a monitor, a printer, and the like.

  The memory unit 14 is configured by a storage medium represented by ROM (Read-only Memory), RAM (Random-Access Memory), and the like. In the first embodiment, the diagnostic data (PET image) processed by the projection data deriving unit 10 and the reconstruction unit 13 and the absorption correction data obtained by the absorption correction data deriving unit 11 are written and stored in the RAM. Read from RAM as needed. The ROM stores in advance programs for performing various nuclear medicine diagnoses, and the controller 7 executes the programs to perform nuclear medicine diagnosis according to the programs.

  In the first embodiment, as shown in FIG. 4B, when the arrangement pitch between the detection elements 3A is p, the rotation mechanism 30 has a pitch p / 2 that is half the arrangement pitch p every predetermined time, that is, A program for rotating the γ-ray detector 3 intermittently at a pitch p / 2 which is a half of the array pitch p is stored in advance in the ROM. Note that the subject M may be intermittently rotated by one round (rotation angle is 360 °), may be intermittently rotated by two or more rounds, or less than one round (rotation angle is 0). (° to 360 °) may be rotated intermittently.

  The projection data deriving unit 10, the absorption correction data deriving unit 11, the absorption correcting unit 12, and the reconstruction unit 13 are, for example, a program stored in a ROM of a storage medium represented by the above-described memory unit 14 or the input unit 8 or the like This is realized by the controller 7 executing a command input by a pointing device represented by. 4 (b), the program described above or a command input by a pointing device typified by the input unit 8 or the like is sent to the rotating mechanism 30 via the controller 7. Just put it in.

  The γ-rays generated from the subject M to which the radiopharmaceutical is administered are converted into light by the scintillator block 3a, and the converted light is photoelectrically converted by the photomultiplier 3b and output to an electrical signal. The electric signal is sent to the projection data deriving unit 10 as image information (pixel).

  Specifically, when a radiopharmaceutical is administered to the subject M, two γ rays are generated due to the disappearance of the positron of the positron emission type RI. The projection data deriving unit 10 checks the position of the scintillator block 3a and the incident timing of the γ-ray, and sends it only when γ-rays are simultaneously incident on the two scintillator blocks 3a that are opposed to each other across the subject M. The obtained image information is determined as appropriate data. When γ rays are incident only on one of the scintillator blocks 3a, the projection data deriving unit 10 treats the image information sent at that time as noise instead of γ rays generated by the disappearance of the positron. Reject.

  As shown in FIG. 4B, the projection data deriving unit 10 has a predetermined value each time the rotation mechanism 30 rotates the γ-ray detector 3 at a pitch p / 2 that is half the arrangement pitch p every predetermined time. The incident timing of γ rays is checked every time, and image information determined as appropriate data is collected. Therefore, the image information is data of a position for each detection element 3A of the rotating γ-ray detector 3. The projection data deriving unit 10 corresponds to the collecting means in the present invention.

  The image information sent to the projection data deriving unit 10 is sent to the absorption correction unit 12 as projection data. Absorption correction data (transmission data) sent from the absorption correction data derivation unit 11 to the absorption correction unit 12 is applied to the projection data sent to the absorption correction unit 12 to absorb γ rays in the body of the subject M. The projection data is corrected in consideration of the above.

  The point source 4 emits γ rays toward the subject M while rotating around the body axis Z of the subject M, and the irradiated γ rays are used as a scintillator block of the γ ray detector 5 for absorption correction data. (Not shown) converts it into light, and the converted light is photoelectrically converted by a photomultiplier (not shown) of the γ-ray detector 5 and output to an electrical signal. The electric signal is sent to the absorption correction data deriving unit 11 as image information (pixel).

  Absorption correction data is obtained based on the image information sent to the absorption correction data deriving unit 11. The absorption correction data deriving unit 11 uses the calculation representing the relationship between the absorption coefficient of γ-rays or X-rays and the energy, so that the projection data for CT, that is, the distribution data of the X-ray absorption coefficients is converted into By converting to distribution data, the distribution data of the γ-ray absorption coefficient is obtained as absorption correction data. The derived absorption correction data is sent to the absorption correction unit 12 described above.

  The corrected projection data is sent to the reconstruction unit 13. The reconstruction unit 13 reconstructs the projection data to obtain a tomographic image taking into account the absorption of γ rays in the body of the subject M. Thus, by providing the absorption correction unit 12 and the reconstruction unit 13, the projection data is corrected based on the absorption correction data and the tomographic image is corrected. The corrected tomographic image is sent to the output unit 9 via the controller 7.

  Next, specific driving by the rotation mechanism 30 will be described with reference to FIG. FIG. 4A is an explanatory diagram schematically showing the relationship between the arrangement pitch p between the conventional detection elements 3A and the detector position, and FIG. 4B is a diagram including Example 2 described later. FIG. 6 is an explanatory diagram schematically illustrating a relationship among an arrangement pitch p between detector elements 3A according to Example 1, a pitch p / 2 that is a half of the arrangement pitch p, and a detector position. Each detection element 3A is arranged in parallel in the rotation direction (circumferential direction) with an arrangement pitch p. However, in FIG. 4, each detection element 3A is shown in a linear form for simplicity of explanation. Yes. In FIG. 4, the detector position is indicated by a one-dot chain line.

  As shown in FIG. 4A, conventionally, the γ-ray detector 3 is intermittently rotated so as to change the position at an arrangement pitch p between the detection elements 3A every predetermined time. On the other hand, as shown in FIG. 4B, in Example 1, including Example 2 to be described later, γ at a pitch p / 2 that is half the array pitch p between the detection elements 3A every predetermined time. The line detector 3 is rotated intermittently. For example, it is assumed that the sensor position A is rotated from the detector position A by the pitch p / 2 and moved to the detector position B. At this time, each detector position is also rotated by a pitch p / 2 as shown by a one-dot chain line in the figure. As a result, the projection data deriving unit 10 collects image information as position data for each detection element 3A of the rotating γ-ray detector 3 (see “data synthesis” in FIG. 4B). This collected data has a detection element density twice as high. This data is sent as projection data to the absorption correction unit 12 as described above to perform absorption correction, and the projection data after the absorption correction is sent to the reconstruction unit 13.

  According to the PET apparatus according to the first embodiment having the above-described configuration, the rotation mechanism 30 rotates and drives the γ-ray detector 3 including the plurality of detection elements 3A that respectively detect γ-rays as follows. . That is, the γ-ray detector 3 is driven to rotate, and the γ-ray detector 3 and the target are within the range of the arrangement pitch p between the detection elements 3A (in this embodiment, a pitch p / 2 that is half the arrangement pitch p). The relative position with respect to the sample M is changed. Then, the projection data deriving unit 10 collects nuclear medicine data (projection data in the first embodiment) at a position for each detection element 3A of the rotating γ-ray detector 3. Conventionally, nuclear medicine data for each arrangement pitch p was collected, but nuclear medicine data is collected within the range of the arrangement pitch p. The γ-ray detector 3 can detect the nuclear medicine data and the projection data deriving unit 10 can collect the nuclear medicine data. As a result, the resolution of nuclear medicine data can be improved without increasing the number of detection elements 3A.

  In the first embodiment, the γ-ray detector 3 is rotationally driven at a pitch p / 2 that is half of the arrangement pitch p, that is, a pitch p / 2 that is a half of the arrangement pitch p. Thus, the rotation mechanism 30 preferably drives the γ-ray detector 3 to rotate at a pitch that is an integral number of the arrangement pitch p. By rotating the γ-ray detector 3 at a pitch of an integer, the conventional nuclear medicine data for each array pitch p can be used as it is, and the nuclear medicine data of the projection data deriving unit 10 can be used. Collection can be performed easily. Further, as illustrated in the rotational drive by the γ-ray detector 3 at a pitch p / 3 that is one third of the arrangement pitch p and a pitch p / 4 that is one fourth of the arrangement pitch p, As long as the γ-ray detector 3 is rotationally driven at a pitch that is a fraction of the pitch p, the integer of the denominator is not particularly limited.

  In the first embodiment, the driving direction of the γ-ray detector 3 is the rotation direction (that is, the circumferential direction) around the body axis Z of the subject M. That is, the rotation mechanism 30 can detect and collect nuclear medicine data in more rotation directions (circumferential directions) by rotating the γ-ray detector 3 around the body axis Z of the subject M. .

  In the first embodiment, the rotation mechanism 30 intermittently rotates the γ-ray detector 3 within a range of the arrangement pitch p every predetermined time (in the first embodiment, a pitch p / 2 that is half the arrangement pitch p). However, the rotation mechanism 30 continuously rotates the γ-ray detector 3 so that the γ-ray detector 3 has a predetermined pitch within the range of the arrangement pitch p (for example, half the arrangement pitch p as in the first embodiment). The projection data deriving unit 10 may collect nuclear medicine data at a position for each detection element 3A until the rotation mechanism 30 rotates at a pitch p / 2). The γ-ray detector 3 may be rotated at an arbitrary pitch within the range.

  As in the former case, when the γ-ray detector 3 is continuously rotated, a storage medium represented by the memory unit 14 or the like is used similarly to the case where the γ-ray detector 3 is intermittently rotated every predetermined time. A program stored in advance in the ROM is sent to the rotation mechanism 30 via the controller 7. In the latter case, when the γ-ray detector 3 is rotated at an arbitrary pitch within the range of the arrangement pitch p at an arbitrary timing, an instruction of an arbitrary pitch that the operator wants to specify at the desired rotation timing is input to the input unit. 8 is sent to the rotating mechanism 30 via the controller 7.

Next, Embodiment 2 of the present invention will be described with reference to the drawings.
FIG. 5 is a side view and a block diagram of a PET-CT diagnostic system including a PET apparatus and an X-ray CT apparatus according to the second embodiment. In addition, illustration of the rotation mechanism 30 is abbreviate | omitted in FIG.

  In the first embodiment described above, the PET apparatus includes the point source 4, and the point source 4 irradiates the same γ-ray as the radiopharmaceutical and transmits through the subject M, so that absorption correction data is obtained as morphological information based on the radiation. However, in the second embodiment, the projection data for CT is used as the absorption correction data.

  The X-ray CT apparatus includes a gantry 21 having an opening 21 a, an X-ray tube 22, and an X-ray detector 23. The X-ray tube 22 and the X-ray detector 23 are disposed to face each other with the subject M interposed therebetween, and are embedded in the gantry 21. A large number of detection elements constituting the X-ray detector 3 are arranged in a fan shape around the body axis Z of the subject M.

  In addition, the X-ray CT apparatus includes a gantry driving unit 24, a high voltage generation unit 25, a collimator driving unit 26, and a CT reconstruction unit 27. The CT reconstruction unit 27 is realized by the controller 7 executing, for example, a program stored in a ROM of a storage medium represented by the memory unit 14 or the like described above or an instruction input from the input unit 8. Note that CT projection data (to be described later) and CT tomographic images processed by the CT reconstruction unit 27 are also written and stored in the RAM of the memory unit 14 in the same manner as in the first embodiment described above. Read from. These CT projection data and CT tomographic images correspond to the X-ray CT data in this invention.

  The gantry driving unit 24 is a mechanism that drives the X-ray tube 22 and the X-ray tube detector 23 to rotate around the body axis Z of the subject M within the gantry 21 while maintaining the facing relationship with each other. The motor is composed of a motor (not shown).

  The high voltage generator 25 generates a tube voltage or tube current of the X-ray tube 22. The collimator driving unit 26 is a mechanism for setting an X-ray irradiation field and driving the collimator (not shown) in the vicinity of the X-ray tube 22 to move in the horizontal direction. It consists of

  In the case of the indirect conversion type X-ray detector 23, the X-ray irradiated from the X-ray tube 22 and transmitted through the subject M is converted into light by a scintillator (not shown) in the X-ray detector 23. The light-sensitive film (not shown) photoelectrically converts the converted light and outputs it as an electrical signal. In the case of the direct conversion type X-ray detector 23, the X-ray is directly converted into an electric signal by a radiation sensitive film (not shown) and output. The electric signal is sent to the CT reconstruction unit 27 as image information (pixel). Image information sent to the CT reconstruction unit 27 is transmitted as projection data for CT.

  The projection data for CT has the form information in the same way as the absorption correction data described in the first embodiment. In the second embodiment, the absorption correction data is used in order to use the projection data for CT as the absorption correction data. In addition to being sent to the deriving unit 11, it is also sent to the CT reconstruction unit 27. Image information (CT projection data) sent to the CT reconstruction unit 27 is reconstructed to obtain a CT tomographic image. This CT tomographic image is sent to the output unit 9 via the controller 7. Since the functions of the subsequent processing units (absorption correction unit 12 and reconstruction unit 13) of the PET apparatus including the absorption correction data deriving unit 11 are the same as those in the first embodiment, description thereof is omitted. Note that the PET tomographic image reconstructed by the reconstruction unit 13 and the CT tomographic image reconstructed by the CT reconstruction unit 27 may be superimposed and output by the output unit 9.

  In the second embodiment, the rotation mechanism 30 (not shown in FIG. 6) detects γ rays at a pitch p / 2 that is half the array pitch p between the detection elements 3A every predetermined time, as in the first embodiment described above. The vessel 3 is rotated intermittently. Of course, as described in the first embodiment, the rotating mechanism 30 continuously rotates the γ-ray detector 3 so that the γ-ray detector 3 has a predetermined pitch within the range of the arrangement pitch p (for example, as in the first embodiment). The projection data deriving unit 10 may collect nuclear medicine data at the position of each detection element 3A until the rotation mechanism 30 rotates at a pitch p / 2 that is half of the arrangement pitch p. The γ-ray detector 3 may be rotated at an arbitrary pitch within the range of the arrangement pitch p at the timing.

  In the case of the system according to the second embodiment, the projection data deriving unit 10 collects nuclear medicine data (projection data in the second embodiment) at each detection element 3A position of the rotating γ-ray detector 3. Then, the collected projection data is subjected to absorption correction, or a PET tomographic image is obtained from the absorption-corrected projection data, and the CT tomographic image is superimposed and output.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, the PET apparatus has been described as an example. However, the present invention detects a single gamma ray and reconstructs a tomographic image of the subject. It can also be applied to devices.

  (2) In each of the above-described embodiments, the PET apparatus includes the point source 4, and the point source 4 emits the same γ-ray as the radiopharmaceutical and passes through the subject M, and as morphological information based on the radiation. Absorption correction data is obtained, and in the second embodiment described above, the CT projection data is used as the absorption correction data, and the absorption correction is performed in each embodiment. However, it is not always necessary to perform the absorption correction.

  (3) In each of the above-described embodiments, the driving unit represented by the rotation mechanism 30 rotates the detection unit represented by the γ-ray detector 3 so that the position is changed at an integer pitch of the arrangement pitch p. Although driven, it is not necessarily limited to a fraction of an integer. If it falls within the range of the arrangement pitch p between the detection elements 3A, the detection means may be driven to rotate so that the position is changed at a pitch of p × α (where 0 <α <1).

  (4) In each of the above-described embodiments, the driving direction of the detection means represented by the γ-ray detector 3 is the rotation direction (that is, the circumferential direction) around the body axis Z of the subject M, but the driving direction is It is not limited to the direction of rotation. For example, the top plate 1 is positioned along the body axis Z direction within the range of the arrangement pitch p between the detection elements 3A (the arrangement pitch p here is the pitch between the detection elements 3A arranged in parallel in the body axis direction). The top plate driving unit 6 is driven so as to change. By moving the top plate 1 in the body axis Z direction, the subject M placed on the top plate 1 also moves in the body axis Z direction, and the relative position between the detection means and the subject M is within the range of the array pitch p. Inside, the top plate drive unit 6 is changed. In this modification, the top plate drive unit 6 corresponds to the drive means in the present invention. In addition, the top plate 1 may be moved up and down, horizontally or diagonally in the direction within the tomographic plane.

  (5) In each of the above-described embodiments, the driving unit represented by the rotation mechanism 30 drives the detection unit represented by the γ-ray detector 3 so that the position is changed within the range of the arrangement pitch p. The relative position between the detection means and the subject M may be changed within the range of the arrangement pitch p by driving only the top plate 1 on which the subject M is placed with the driving means fixed. For example, by fixing the γ-ray detector 3 and rotating the top plate 1 around the body axis Z of the subject M so as to change the position within the range of the arrangement pitch p, the detection means and the subject M The relative position may be changed within the range of the arrangement pitch p. Further, both the driving means and the top board 1 are driven within the range of the arrangement pitch p (for example, moved in opposite directions), and the relative position between the detection means and the subject M is changed within the range of the arrangement pitch p. May be. Therefore, if the driving unit drives at least one of the detecting unit and the subject M and changes the relative position between the detecting unit and the subject M within the range of the arrangement pitch p, the driving target is particularly limited. Not.

(A) is a side view and block diagram of a PET (Positron Emission Tomography) apparatus according to the first embodiment, and (b) is an enlarged view showing a specific configuration of a γ-ray detector. It is a schematic front view of a rotation mechanism and a γ-ray detector that rotate the γ-ray detector around the body axis Z of the subject. It is a schematic front view of a gamma ray detector. (A) is explanatory drawing which showed typically the arrangement | positioning pitch between the conventional detection elements, and the relationship of a detector position, (b) is the arrangement pitch between the detection elements which concern on each Example, and the half of arrangement pitch It is explanatory drawing which showed typically the relationship between a pitch and a detector position. It is the side view and block diagram of the diagnostic system of PET-CT provided with the PET apparatus and X-ray CT apparatus which concern on Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... γ-ray detector 3A ... Detection element 10 ... Projection data deriving part 30 ... Rotating mechanism p ... Arrangement pitch M ... Subject

Claims (7)

  A nuclear medicine diagnostic apparatus for obtaining nuclear medicine data of a subject based on radiation generated from a subject to which a radiopharmaceutical is administered, and a detection means composed of a plurality of detection elements that respectively detect the radiation, Drive means for driving at least one of the detection means and the subject to change the relative position of the detection means and the subject within the range of the arrangement pitch between the detection elements, and collecting nuclear medicine data at each relative position A nuclear medicine diagnostic apparatus, comprising:   2. The nuclear medicine diagnosis apparatus according to claim 1, wherein the driving unit drives at least one of the detection unit and the subject so that the relative position is changed at a pitch of an integer of the arrangement pitch. Features nuclear medicine diagnostic equipment.   3. The nuclear medicine diagnosis apparatus according to claim 1, wherein the driving means rotates at least one of the detection means and the subject around a body axis of the subject.   4. The nuclear medicine diagnosis apparatus according to claim 1, wherein the driving unit is configured to change the relative position at a predetermined pitch within a range of the arrangement pitch every predetermined time. A nuclear medicine diagnostic apparatus, wherein at least one of the subjects is intermittently driven.   The nuclear medicine diagnosis apparatus according to any one of claims 1 to 3, wherein the driving unit continuously drives at least one of the detection unit and the subject, and at least one of the detection unit and the subject is the device. The nuclear medicine diagnosis apparatus, wherein the collection means collects the nuclear medicine data at a relative position for each detection element with respect to the subject before being driven at a predetermined pitch within the arrangement pitch range.   The nuclear medicine diagnosis apparatus according to any one of claims 1 to 3, wherein the driving unit moves at least one of the detection unit and the subject at an arbitrary timing within a range of the arrangement pitch at an arbitrary timing. A nuclear medicine diagnostic apparatus characterized by being driven.   A diagnostic system for use in the nuclear medicine diagnostic apparatus according to any one of claims 1 to 6, wherein the system includes a nuclear medicine diagnostic apparatus and an X-ray CT apparatus. The medical diagnostic apparatus obtains nuclear medicine data of the subject based on radiation generated from the subject to which the radiopharmaceutical is administered, and the X-ray CT apparatus is irradiated from the outside of the subject and passes through the subject. X-ray CT data is obtained based on X-rays, and the nuclear medicine diagnosis apparatus drives at least one of detection means, a detection means, and a subject, each of which includes a plurality of detection elements that detect the radiation, A diagnostic system comprising: drive means for changing the relative position between the detection means and the subject within a range of arrangement pitch between the detection elements; and collection means for collecting nuclear medicine data at each relative position .

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