JP7321798B2 - Reconstruction device and radiological diagnosis device - Google Patents

Description

Embodiments of the present invention relate to reconstruction apparatus and radiological diagnostic apparatus.

In a radiological diagnostic apparatus such as an X-ray CT (Computed Tomography) apparatus, when reconstructing CT image data, a plurality of matrix sizes (for example, 512×512, 1024×1024, 2048×2048, etc.) are selected for reconstruction. A matrix size to be used for construction is selected.

When the matrix size is increased, while high spatial resolution is obtained, the amount of calculation increases, so the time required for reconstruction (reconstruction time) becomes longer. Here, for example, the geometry of the gantry (CT scanner) (the distance between the X-ray tube (tube) and the detector, the interval between the detector elements in the channel direction, etc.) and the acquisition conditions (selected by the operator at the time of scanning The maximum spatial resolution obtainable in a scan is limited by the possible X-ray tube focus size, FOV (Field Of View) size, etc.). For this reason, depending on the geometry of the gantry described above and the acquisition conditions described above, even if the matrix size used for reconstruction is increased, the spatial resolution does not exceed a certain height. It takes a long time.

Also, for example, an unnecessarily large matrix size may be selected by the operator for the spatial resolution required by the clinical site. In this case as well, image data with an unnecessarily high spatial resolution is reconstructed, resulting in an unnecessarily long reconstruction time.

JP-A-09-262219

A problem to be solved by the present invention is to provide a reconstruction apparatus and a radiodiagnostic apparatus capable of reconstructing image data with optimal spatial resolution in an optimal reconstruction time.

A reconstruction device according to an embodiment includes a determination unit and a reconstruction processing unit. The decision unit decides a matrix size according to a collection condition when data is collected by the collection unit and a positional relationship of a plurality of elements constituting the collection unit. The reconstruction processing unit uses the data to reconstruct matrix-sized image data.

FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus according to the first embodiment. FIG. 2 is a flow chart showing an example of the flow of processing executed by the X-ray CT apparatus according to the first embodiment. FIG. 3 is a diagram showing an example of the configuration of an X-ray CT apparatus according to the second embodiment. FIG. 4 is a flow chart showing an example of the flow of processing executed by the X-ray CT apparatus according to the second embodiment. FIG. 5 is a diagram showing an example of a reception screen displayed in step S201 in the second embodiment. FIG. 6 is a diagram showing an example of the data structure of a database according to the third embodiment. FIG. 7 is a diagram showing an example of the data structure of a database according to the fourth embodiment. FIG. 8 is a diagram for explaining a first modification. FIG. 9 is a diagram for explaining a second modification.

Hereinafter, embodiments of a reconstruction apparatus and a radiodiagnostic apparatus will be described in detail with reference to the drawings. Note that the contents described in one embodiment or modified example may be similarly applied to other embodiments or other modified examples.

(First embodiment)
An example of the configuration of an X-ray CT apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus 1 according to the first embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 has a gantry device 10, a bed device 30, and a console device 40. As shown in FIG. The X-ray CT apparatus 1 is an example of a radiodiagnostic apparatus.

In FIG. 1, the rotation axis of the rotating frame 13 or the longitudinal direction of the top plate 33 of the bed apparatus 30 in the non-tilt state is the Z-axis direction. Further, the axial direction perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction. Further, the axial direction perpendicular to the Z-axis direction and the X-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. Note that FIG. 1 illustrates the gantry 10 from a plurality of directions for explanation, and shows the case where the X-ray CT apparatus 1 has one gantry 10 .

The gantry device 10 includes an X-ray tube 11, an X-ray detector 12, a rotating frame 13, an X-ray high voltage device 14, a control device 15, a wedge 16, a collimator 17, and a DAS (Data Acquisition System). 18. The gantry device 10 is an example of a collection unit.

The X-ray tube 11 is a vacuum tube having a cathode (filament) that generates thermoelectrons and an anode (target) that generates X-rays upon collision with thermoelectrons. The X-ray tube 11 emits thermal electrons from the cathode to the anode by applying a high voltage from the X-ray high voltage device 14, thereby generating X-rays to be irradiated to the subject P. As shown in FIG. For example, the X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermal electrons. Note that the X-ray tube 11 is an example of an X-ray generator.

The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and passed through the subject P, and outputs a signal corresponding to the detected X-ray dose to the DAS 18 . The X-ray detector 12 has, for example, a plurality of detector element arrays in which a plurality of detector elements are arranged in the channel direction along one circular arc centered on the focal point of the X-ray tube 11 . The X-ray detector 12 has, for example, a structure in which a plurality of detector element arrays each having a plurality of detector elements arranged in the channel direction are arranged in the column direction (slice direction, row direction). Also, the X-ray detector 12 is, for example, an indirect conversion type detector having a grid, a scintillator array, and a photosensor array. The scintillator array has a plurality of scintillators. The scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays. The grid is arranged on the surface of the scintillator array on the X-ray incident side and has an X-ray shielding plate that absorbs scattered X-rays. Note that the grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal, and has photosensors such as photodiodes, for example. The X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into electrical signals. Also, the X-ray detector 12 is an example of an X-ray detection unit.

The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other and rotates the X-ray tube 11 and the X-ray detector 12 by the control device 15 . For example, the rotating frame 13 is a casting made of aluminum. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 can also support the X-ray high voltage device 14, the wedge 16, the collimator 17, the DAS 18, and the like. Additionally, the rotating frame 13 may further support various configurations not shown in FIG. Hereinafter, in the gantry device 10, the rotating frame 13 and the portion that rotates together with the rotating frame 13 are also referred to as a rotating portion.

The X-ray high-voltage device 14 has electric circuits such as a transformer and a rectifier, and includes a high-voltage generator that generates a high voltage to be applied to the X-ray tube 11 and an X-ray that the X-ray tube 11 generates. and an X-ray controller for controlling the output voltage according to. The high voltage generator may be of a transformer type or an inverter type. The X-ray high-voltage device 14 may be provided on the rotating frame 13 or may be provided on a fixed frame (not shown).

The control device 15 has a processing circuit having a CPU (Central Processing Unit) and the like, and drive mechanisms such as motors and actuators. The control device 15 receives an input signal from the input interface 43 and controls the operations of the gantry device 10 and the bed device 30 . For example, the control device 15 controls the rotation of the rotating frame 13, the tilt of the gantry device 10, the motions of the bed device 30 and the tabletop 33, and the like. As an example, the control device 15 rotates the rotating frame 13 about an axis parallel to the X-axis direction based on input inclination angle (tilt angle) information as control for tilting the gantry device 10 . Note that the control device 15 may be provided in the gantry device 10 or may be provided in the console device 40 .

Wedge 16 is a filter for adjusting the dose of X-rays emitted from X-ray tube 11 . Specifically, the wedge 16 transmits the X-rays emitted from the X-ray tube 11 so that the distribution of the X-rays emitted from the X-ray tube 11 to the subject P becomes a predetermined distribution. is a filter that attenuates For example, the wedge 16 is a wedge filter or a bow-tie filter, which is a filter made of aluminum or the like so as to have a predetermined target angle and a predetermined thickness.

The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16, and a slit is formed by combining a plurality of lead plates or the like. Note that the collimator 17 may also be called an X-ray diaphragm. 1 shows the case where the wedge 16 is arranged between the X-ray tube 11 and the collimator 17, the case where the collimator 17 is arranged between the X-ray tube 11 and the wedge 16 good too. In this case, the wedge 16 transmits and attenuates the X-rays emitted from the X-ray tube 11 and whose irradiation range is limited by the collimator 17 .

The DAS 18 collects X-ray signals detected by each detection element of the X-ray detector 12 . For example, the DAS 18 has an amplifier that performs amplification processing on the electrical signal output from each detection element, and an A/D converter that converts the electrical signal, which is an analog signal, into a digital signal, and generates detection data. do.

The data generated by the DAS 18 is transmitted from a transmitter having a light emitting diode (LED) provided on the rotating frame 13 to a non-rotating portion (for example, a fixed frame, etc.) of the gantry 10 by optical communication. (not shown) is transmitted to a receiver having a photodiode and transferred to the console device 40 . Here, the non-rotating portion is, for example, a fixed frame or the like that rotatably supports the rotating frame 13 . The method of transmitting data from the rotating frame 13 to the non-rotating portion of the gantry 10 is not limited to optical communication, and any non-contact data transmission method may be employed. I don't mind if you hire me.

The X-ray detector 12 and DAS 18 detect X-rays emitted from the X-ray tube 11 and collect projection data. Such X-ray detector 12 and DAS 18 are an example of an X-ray detector.

The bed device 30 is a device for placing and moving a subject P to be scanned, and has a base 31 , a bed driving device 32 , a top board 33 and a support frame 34 . The base 31 is a housing that supports the support frame 34 so as to be vertically movable. The bed drive device 32 is a drive mechanism for moving the table 33 on which the subject P is placed in the longitudinal direction of the table 33, and includes a motor, an actuator, and the like. A top plate 33 provided on the upper surface of the support frame 34 is a plate on which the subject P is placed. Note that the bed driving device 32 may move the support frame 34 in the longitudinal direction of the top plate 33 in addition to the top plate 33 .

The console device 40 has a memory 41 , a display 42 , an input interface 43 and a processing circuit 44 . Although the console device 40 is described as being separate from the gantry device 10 , the console device 40 or a part of each component of the console device 40 may be included in the gantry device 10 . The console device 40 is an example of a reconfiguration device.

The memory 41 is implemented by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. The memory 41 stores projection data and reconstructed image data, for example. Also, for example, the memory 41 stores a program for the circuit included in the X-ray CT apparatus 1 to realize its function. Note that the memory 41 may be realized by a server group (cloud) connected to the X-ray CT apparatus 1 via a network. The memory 41 is an example of a storage unit.

The display 42 displays various information. For example, the display 42 displays an image indicated by the image data generated by the processing circuit 44, and displays a GUI (Graphical User Interface) for receiving various operations from operators such as doctors and radiological technologists. or For example, the display 42 is a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 42 may be of a desktop type, or may be configured by a tablet terminal or the like capable of wireless communication with the main body of the console device 40 .

The input interface 43 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 44 . For example, the input interface 43 allows the operator to input acquisition conditions for acquiring projection data, reconstruction conditions for reconstructing CT image data, image processing conditions for generating post-processed images from CT image data, and the like. accept from For example, the input interface 43 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad that performs input operations by touching the operation surface, a touch screen that integrates a display screen and a touch pad, and an optical sensor. It is realized by the used non-contact input circuit, voice input circuit, or the like. Note that the input interface 43 may be provided in the gantry device 10 . Also, the input interface 43 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the console device 40 . Also, the input interface 43 is not limited to having physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the console device 40 and outputs this electrical signal to the processing circuit 44 is an example of the input interface 43. included.

A processing circuit 44 controls the operation of the entire X-ray CT apparatus 1 . Note that the processing circuit 44 is not limited to being included in the console device 40 . For example, the processing circuit 44 may be included in an integrated server that collectively processes detection data acquired by a plurality of X-ray CT apparatuses. For example, an integrated server connected to the X-ray CT apparatus 1 via a network may have the processing circuit 44 . In this case, the X-ray CT apparatus 1 transmits the acquired projection data to the integration server. The integration server then receives the projection data. Then, the processing circuit 44 of the integration server executes various processes described below on the received projection data. An integration server is an example of a reconfiguring device.

For example, processing circuitry 44 performs system control functions 441 , preprocessing functions 442 , decision functions 443 , reconstruction processing functions 444 , image processing functions 445 and output functions 446 . For example, the processing circuit 44 reads out a program (control program) corresponding to the system control function 441 from the memory 41 and executes it, so that the processing circuit 44 may controls various functions of

The system control function 441 controls the X-ray CT apparatus 1 to perform positioning imaging. For example, the system control function 441 fixes the position of the X-ray tube 11 at a predetermined rotation angle, and irradiates the subject P with X-rays from the X-ray tube 11 while moving the top plate 33 in the Z direction. , to perform positioning shooting. Further, the processing circuit 44 reads out and executes a program corresponding to the reconstruction processing function 444 from the memory 41 to generate positioning image data based on X-ray signals acquired by positioning imaging. Note that the positioning image data may also be called scanogram image data or scout image data.

The system control function 441 also controls the X-ray CT apparatus 1 to perform a main scan for acquiring projection data. For example, the system control function 441 sets scan conditions (acquisition conditions) (for example, acquisition FOV, tube voltage, tube current, etc.) for the main scan based on the positioning image data. The system control function 441 generates timing data indicating the timing of changing the tube voltage supplied to the X-ray tube 11 as an acquisition condition, for example, and stores the generated timing data in the memory 41 . Next, the system control function 441 moves the subject P into the imaging port of the gantry device 10 by controlling the bed driving device 32 . Also, the system control function 441 adjusts the aperture and position of the collimator 17 . Also, the system control function 441 rotates the rotating portion by controlling the control device 15 .

Also, the system control function 441 supplies a high voltage to the X-ray tube 11 by controlling the X-ray high voltage device 14 . As a result, the X-ray tube 11 generates X-rays with which the subject P is irradiated.

While the main scan is being performed by the system control function 441, the multiple DASs 18 collect multiple X-ray signals detected by the multiple detector elements and generate detection data. Further, the processing circuit 44 preprocesses the detection data output from the DAS 18 by reading out a program corresponding to the preprocessing function 442 from the memory 41 and executing it. For example, the preprocessing function 442 performs preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the detection data output from the DAS 18 . Data after preprocessing is referred to as raw data. Also, the detected data before preprocessing and the raw data after preprocessing are referred to as projection data. Projection data is an example of data.

The processing circuit 44 also reads out a program corresponding to the determination function 443 from the memory 41 and executes it to determine the matrix size used for reconstruction. Decision function 443 is an example of a decision unit. Details of the decision function 443 will be described later.

The processing circuit 44 also reads out a program corresponding to the reconstruction processing function 444 from the memory 41 and executes it to reconstruct CT image data based on the raw data after preprocessing. Specifically, the reconstruction processing function 444 reconstructs CT image data by performing reconstruction processing using the filtered back projection method, the iterative reconstruction method, or the like on the preprocessed raw data. . The reconstruction processing function 444 is an example of a reconstruction processing unit. CT image data is an example of image data.

Further, the processing circuit 44 performs various image processing on the CT image data by reading a program corresponding to the image processing function 445 from the memory 41 and executing the program. For example, the image processing function 445 converts the reconstructed CT image data into tomographic image data or three-dimensional image data of an arbitrary cross section by a known method based on an input operation or the like received from the operator via the input interface 43. Convert to The image processing function 445 also stores tomographic image data and three-dimensional image data in the memory 41 .

Further, the processing circuit 44 reads out a program corresponding to the output function 446 from the memory 41 and executes it to output tomographic image data, three-dimensional image data, CT image data, and the like. For example, the output function 446 causes the display 42 to display various images such as a tomographic image indicated by the tomographic image data and a CT image indicated by the CT image data. The output function 446 is an example of a display controller. Also, for example, the output function 446 outputs tomographic image data, three-dimensional image data, and CT image data to an external device (for example, a server device that stores image data) connected to the X-ray CT apparatus 1 via a network. output to

In the X-ray CT apparatus 1 shown in FIG. 1, each processing function is stored in the memory 41 in the form of a computer-executable program. The processing circuit 44 is a processor that implements a function corresponding to each program by reading each program from the memory 41 and executing the program. In other words, the processing circuit 44 in a state where each program has been read has a function corresponding to the read program. Note that in FIG. 1, the processing functions of the system control function 441, the preprocessing function 442, the determination function 443, the reconstruction processing function 444, the image processing function 445, and the output function 446 are realized by a single processing circuit 44. Although the case is shown, the embodiment is not limited to this. For example, the processing circuit 44 may be configured by combining a plurality of independent processors, and each processor may implement each processing function by executing each program. Further, each processing function of the processing circuit 44 may be appropriately distributed or integrated in a single or a plurality of processing circuits and implemented.

The term "processor" used in the above description is, for example, a CPU, a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), or a programmable logic device (for example, a simple programmable logic device ( Circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), or Field Programmable Gate Array (FPGA)). The processor implements functions by reading and executing programs stored in the memory 41 .

In FIG. 1, the single memory 41 has been described as storing each program corresponding to each processing function. However, a configuration may be adopted in which a plurality of memories 41 are distributed and the processing circuit 44 reads corresponding programs from individual memories 41 . Also, instead of storing the program in the memory 41, the program may be configured to be directly embedded in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit.

Also, the processing circuit 44 may implement various functions using a processor of an external device connected via a network. For example, the processing circuit 44 reads and executes a program corresponding to each function from the memory 41, and uses an external workstation or server group (cloud) connected to the X-ray CT apparatus 1 via a network as computational resources. , each function shown in FIG. 1 may be realized.

An example of the configuration of the X-ray CT apparatus 1 has been described above. Under such a configuration, the X-ray CT apparatus 1 executes various processes described below so as to reconstruct image data with optimal spatial resolution in optimal reconstruction time.

FIG. 2 is a flow chart showing an example of the flow of processing executed by the X-ray CT apparatus 1 according to the first embodiment. As shown in the example of FIG. 2, the determination function 443 determines the acquisition condition based on the acquisition conditions used when acquiring the projection data and the positional relationship of the plurality of elements that configure the gantry device 10 when acquiring the projection data. Then, the value "Z" (mm) indicating the highest spatial resolution obtained from this acquisition condition and positional relationship is determined (step S101). Here, the value "Z" is a value indicating the length of one side of one picture element (pixel). The smaller the value 'Z', the higher the spatial resolution indicated by the value 'Z'.

A specific example of the processing in step S101 will be described. For example, the memory 41 stores information indicating the size of the focus of the X-ray tube 11 (focus size) and information indicating the number of views (the number of projections to be collected) as acquisition conditions used when acquiring projection data. remembered. The memory 41 also stores information indicating the distance between the X-ray tube 11 and the X-ray detector 12 as the positional relationship of a plurality of elements constituting the gantry 10 when acquiring projection data, Information indicating the distance (pitch) between two adjacent detection elements in the channel direction of the line detector 12 is stored. The distance between the X-ray tube 11 and the X-ray detector 12 is, for example, the distance between the focal point of the X-rays and the detection surface of the detection element. Then, in step S<b>101 , the determination function 443 acquires these pieces of information from the memory 41 . Then, the determination function 443 determines the value "Z ” is calculated. When a plurality of X-ray signals output from a plurality of detection elements are bundled by the DAS 18 and output as one detection data, the plurality of detection elements are regarded as one detection element and The distance (pitch) between two adjacent detection elements may be used as the positional relationship described above. More specifically, a database (not shown) is stored in memory 41 . In this database, a record in which a combination of acquisition conditions and positional relationships and a value indicating the highest spatial resolution obtained from this combination are associated and registered is registered for each combination of acquisition conditions and positional relationships. there is Then, the determination function 443 acquires the value "Z" indicating the highest spatial resolution corresponding to the combination of the acquired acquisition condition and the acquired positional relationship from the database, and determines the value "Z" indicating the highest spatial resolution. decide.

Then, the determination function 443 acquires the FOV "A" (mm) selected by the operator when collecting the projection data (step S102). For example, the memory 41 stores information indicating FOV "A". Then, in step S102, the determination function 443 acquires information indicating the FOV "A" from the memory 41. FIG.

Here, the FOV is, for example, an acquisition FOV or a reconstruction FOV. Acquisition FOV is a range (acquisition range) in which projection data is acquired. The reconstruction FOV is the same range as the acquisition range or a partial range of the acquisition range, and is a range (reconstruction range) for which projection data is to be reconstructed.

Then, the determination function 443 determines "B" of the matrix size "B×B" used for reconstruction based on the value "Z" indicating the highest spatial resolution and the FOV "A" using the following formula (1): Determine (step S103).

B=A/Z (1)

That is, the determination function 443 determines the matrix size "B" represented by the product "B x B" of the number "B" of pixels arranged in the row direction and the number "B" of pixels arranged in the column direction. do.

In this way, the determination function 443 determines the matrix size according to the acquisition condition and the positional relationship described above. Further, the determination function 443 determines the matrix size based on the spatial resolution indicated by the value “Z” according to the above-described acquisition conditions and the above-described positional relationship, and the projection data acquisition range or the projection data reconstruction range. decide.

Then, the reconstruction processing function 444 uses the projection data to reconstruct CT image data with the determined matrix size of "B×B" (step S104). Thereby, the reconstruction processing function 444 reconstructs CT image data having the highest spatial resolution obtained from the acquisition conditions and the positional relationship described above. That is, the reconstruction processing function 444 reconstructs the CT image data with a matrix size corresponding to this highest spatial resolution. Thus, in the first embodiment, reconstruction is not performed with matrix sizes that are unnecessarily larger than the matrix size corresponding to the highest spatial resolution. Therefore, in the first embodiment, it is possible to prevent the occurrence of a situation in which the reconstruction time becomes unnecessarily long even though the spatial resolution does not exceed a certain level. Thus, in the first embodiment, CT image data with optimal spatial resolution can be reconstructed in optimal reconstruction time.

Then, the output function 446 causes the display 42 to display information indicating the CT image represented by the reconstructed CT image data and the matrix size "B×B" (step S105), and ends the process.

The first embodiment has been described above. According to the first embodiment, as described above, CT image data having the optimum spatial resolution can be reconstructed in the optimum reconstruction time.

(Second embodiment)
Next, an X-ray CT apparatus 1 according to a second embodiment will be described. In the second embodiment, the X-ray CT apparatus 1 receives a desired spatial resolution from the operator, compares the received spatial resolution with the spatial resolution according to the above-described acquisition conditions and the above-described positional relationship, and finds a low Determine the matrix size based on the spatial resolution of one.

Hereinafter, in the description of the second embodiment, differences from the first embodiment will be mainly described, and the description of the same configuration as the first embodiment may be omitted. FIG. 3 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the second embodiment. As shown in FIG. 3, the processing circuit 44 according to the second embodiment differs from the processing circuit 44 according to the first embodiment in that it includes a reception function 447 . The reception function 447 is an example of a reception unit.

FIG. 4 is a flow chart showing an example of the flow of processing executed by the X-ray CT apparatus 1 according to the second embodiment. As shown in the example of FIG. 4, the output function 446 displays on the display 42 a screen (acceptance screen) for accepting a value indicating the spatial resolution required when diagnosing a part to be diagnosed (part to be imaged). (step S201).

FIG. 5 is a diagram showing an example of a reception screen displayed in step S201 in the second embodiment. For example, in step S201, the output function 446 causes the display 42 to display the reception screen 50 illustrated in FIG. The reception screen 50 has a text box 51 and a character string "Please enter a value that indicates the spatial resolution required for the site to be diagnosed." When such a reception screen 50 is displayed, the operator inputs a value indicating the spatial resolution necessary for diagnosing the site to be diagnosed in the text box 51 via the input interface 43 . Then, the reception function 447 receives the value indicating the spatial resolution input in the text box 51 . In the following description, the value indicating the spatial resolution accepted by the acceptance function 447 is expressed as "Z1" (mm). Here, the value "Z1" is a value indicating the length of one side of one pixel. The smaller the value “Z1”, the higher the spatial resolution indicated by the value “Z1”. The spatial resolution indicated by the value "Z1" is an example of the first spatial resolution.

The determination function 443 then determines whether or not the reception function 447 has received the value "Z1" indicating the spatial resolution (step S202). If the reception function 447 determines that the value "Z1" indicating the spatial resolution has not been received (step S202: No), the decision function 443 again receives the value "Z1" indicating the spatial resolution from the reception function 447 in step S202. ” is accepted.

On the other hand, when it is determined that the value “Z1” indicating the spatial resolution has been received by the receiving function 447 (step S202: Yes), the determining function 443 executes the following process. For example, the determination function 443 determines a value "Z2" ( mm) is determined (step S203). Here, the value "Z2" is a value indicating the length of one side of one pixel. The smaller the value “Z2”, the higher the spatial resolution indicated by the value “Z2”. The spatial resolution indicated by the value "Z2" is an example of the second spatial resolution.

Then, the determination function 443 compares the value “Z1” indicating the spatial resolution with the value “Z2” indicating the spatial resolution, and determines whether the value “Z2” indicating the spatial resolution is equal to or less than the value “Z1” indicating the spatial resolution. It is determined whether or not (step S204). Then, when it is determined that the value "Z2" indicating the spatial resolution is equal to or less than the value "Z1" indicating the spatial resolution (step S204: Yes), the determination function 443 proceeds to step S205.

Here, the case where the value "Z2" indicating the spatial resolution is smaller than the value "Z1" indicating the spatial resolution will be described. In this case, the spatial resolution indicated by the value "Z2" is higher than the spatial resolution indicated by the value "Z1". Then, the X-ray CT apparatus 1 can reconstruct CT image data having the spatial resolution indicated by the value "Z2". However, for example, the operator considers that the spatial resolution indicated by the value "Z1" is sufficient for the CT image data. In such a case, if the X-ray CT apparatus 1 reconstructs the CT image data with a matrix size corresponding to the spatial resolution indicated by the value "Z2", image data with an unnecessarily high spatial resolution is obtained, and It unnecessarily lengthens the reconstruction time. Therefore, in steps S205 to S207 below, the X-ray CT apparatus 1 reconstructs CT image data with a matrix size corresponding to the desired spatial resolution indicated by the value "Z1".

The determination function 443 acquires the FOV "A" (mm) selected by the operator when acquiring the projection data (step S205), as in step S102 described above.

Then, the determination function 443 determines "B" of the matrix size "B×B" used for reconstruction based on the value "Z1" indicating the spatial resolution and the FOV "A" by the following formula (2) (Step S206).

B=A/Z1 (2)

Thus, the determination function 443 determines the matrix size based on the result of comparing the spatial resolution indicated by the value "Z1" and the spatial resolution indicated by the value "Z2". For example, in step S206, the determination function 443 determines based on the lower spatial resolution (spatial resolution indicated by the value "Z1") of the spatial resolution indicated by the value "Z1" and the spatial resolution indicated by the value "Z2". to determine the matrix size.

Then, the reconstruction processing function 444 reconstructs CT image data of the determined matrix size "B×B" using the projection data in the same manner as in step S104 described above (step S207). Thereby, the reconstruction processing function 444 reconstructs CT image data having the spatial resolution desired by the operator. That is, the reconstruction processing function 444 reconstructs the CT image data with a matrix size corresponding to the desired spatial resolution. Therefore, in step S207 of the second embodiment, reconstruction is not performed with a matrix size that is unnecessarily larger than the matrix size corresponding to the desired spatial resolution. Therefore, in step S207 of the second embodiment, it is possible to suppress the occurrence of a situation in which the reconstruction time becomes unnecessarily long. Thus, in step S207 of the second embodiment, CT image data having optimum spatial resolution can be reconstructed in optimum reconstruction time.

On the other hand, when determining that the value "Z2" indicating the spatial resolution is larger than the value "Z1" indicating the spatial resolution (step S204: No), the determination function 443 proceeds to step S209.

Here, a case where the value "Z2" indicating the spatial resolution is greater than the value "Z1" indicating the spatial resolution will be described. In this case, the spatial resolution indicated by the value "Z1" is higher than the spatial resolution indicated by the value "Z2". The operator considers that the spatial resolution indicated by the value "Z1" is sufficient for the spatial resolution of the CT image data. However, the upper limit of the spatial resolution that can be obtained by the X-ray CT apparatus 1 is the spatial resolution indicated by the value "Z2" and does not reach the spatial resolution indicated by the value "Z1". In such a case, when the X-ray CT apparatus 1 reconstructs the CT image data with a matrix size corresponding to the spatial resolution indicated by the value "Z1", the spatial resolution of the CT image data becomes the spatial resolution indicated by the value "Z2". Although the resolution is not exceeded, the reconstruction time becomes unnecessarily long. Therefore, in steps S209 to S211 below, the X-ray CT apparatus 1 reconstructs CT image data with a matrix size corresponding to the spatial resolution indicated by the value "Z2".

In step S209, the determination function 443 acquires the FOV "A" (mm) selected by the operator when acquiring the projection data, as in step S102 described above.

Then, the determination function 443 determines "B" of the matrix size "B×B" used for reconstruction based on the value "Z2" indicating the spatial resolution and the FOV "A" by the following formula (3) (Step S210).

B=A/Z2 (3)

Thus, the determination function 443 determines the matrix size based on the result of comparing the spatial resolution indicated by the value "Z1" and the spatial resolution indicated by the value "Z2". For example, in step S210, the determination function 443 determines based on the lower spatial resolution (spatial resolution indicated by the value "Z2") of the spatial resolution indicated by the value "Z1" and the spatial resolution indicated by the value "Z2". to determine the matrix size.

Then, the reconstruction processing function 444 reconstructs CT image data with the determined matrix size of "B×B" using the projection data, as in step S104 described above (step S211). Thereby, the reconstruction processing function 444 reconstructs CT image data having the highest spatial resolution obtained from the acquisition conditions and the positional relationship described above. That is, the reconstruction processing function 444 reconstructs the CT image data with a matrix size corresponding to the highest spatial resolution. Therefore, in step S211 of the second embodiment, reconstruction is not performed with a matrix size that is unnecessarily larger than the matrix size corresponding to the highest spatial resolution obtained from the above-described acquisition conditions and the above-described positional relationship. Therefore, in step S211 of the second embodiment, it is possible to suppress the occurrence of a situation in which the reconstruction time is unnecessarily long. Thus, in step S211 of the second embodiment, CT image data having optimum spatial resolution can be reconstructed in optimum reconstruction time.

Then, the output function 446 causes the display 42 to display information indicating the CT image and the matrix size "B×B" (step S208), and ends the process.

The second embodiment has been described above. According to the second embodiment, as described above, CT image data having the optimum spatial resolution can be reconstructed in the optimum reconstruction time.

(Third embodiment)
Next, an X-ray CT apparatus 1 according to a third embodiment will be described. In the above-described second embodiment, the case where the operator inputs the value "Z1" indicating the spatial resolution required when diagnosing the part to be diagnosed has been described. However, in the third embodiment, the X-ray CT apparatus 1 automatically acquires the value "Z1" indicating the spatial resolution required when diagnosing the part to be diagnosed.

In the following description of the third embodiment, differences from the second embodiment are mainly described. Specifically, the point that the X-ray CT apparatus 1 automatically acquires the value "Z1" indicating the spatial resolution required when diagnosing the part to be diagnosed will be mainly described. In addition, in the description of the third embodiment, the description of the configuration similar to that of the second embodiment may be omitted. The processing circuit 44 according to the third embodiment differs from the processing circuit 44 according to the second embodiment in that it does not have a reception function 447 .

FIG. 6 is a diagram showing an example of the data structure of the database 60 according to the third embodiment. A database 60 shown in the example of FIG. 6 is stored in the memory 41 . In the database 60, a record in which a site to be diagnosed (site to be imaged) is associated with a value indicating the spatial resolution required for diagnosis is registered for each site to be imaged.

A record in the database 60 includes items of “site” and “value indicating spatial resolution”. Information indicating a possible part to be imaged is registered in the item "part". A value (mm) indicating the spatial resolution required for diagnosis of the region indicated by the information registered in the “region” item is registered in the “value indicating spatial resolution” item. For example, the first record of the database 60 shown in FIG. 6 indicates that the value indicating the spatial resolution required for head diagnosis is "A" (mm). The same applies to other records.

Then, in the third embodiment, the determination function 443 executes the processing described below instead of the processing in steps S201 and S202 of the second embodiment. For example, the determination function 443 first identifies the region to be imaged. For example, the memory 41 stores information about the body part to be imaged. Then, the determination function 443 acquires the information about the body part to be imaged stored in the memory 41 and specifies the body part to be imaged indicated by the acquired information.

Then, the determination function 443 refers to the database 60 and acquires from the database 60 a value indicating the spatial resolution corresponding to the identified region to be imaged. Specifically, the determining function 443 identifies, from all the records in the database 60, a record in which information indicating a body part to be imaged is registered in the "site" item. Then, the determination function 443 acquires the value registered in the “value indicating spatial resolution” item of the specified record. In the following description, the acquired value is written as "Z1".

Then, the determination function 443 uses the value "Z1" indicating the spatial resolution to execute each process of each step after step S203, as in the second embodiment.

The third embodiment has been described above. In the third embodiment, the memory 41 associates and stores each of a plurality of parts of the subject and each of a plurality of spatial resolutions. Then, the determination function 443 acquires the spatial resolution corresponding to the part to be imaged from the memory 41 . Then, the determination function 443 determines the matrix size based on the result of comparison between the obtained spatial resolution and the spatial resolution according to the acquisition conditions and the positional relationship described above.

According to the third embodiment, as in the second embodiment, CT image data having optimum spatial resolution can be reconstructed in optimum reconstruction time. Further, according to the third embodiment, the value indicating the spatial resolution is automatically obtained without the operator inputting the value indicating the spatial resolution. Therefore, according to the third embodiment, it is possible to reconstruct CT image data having the optimum spatial resolution in the optimum reconstruction time while reducing the complexity of the operator.

(Fourth embodiment)
Next, an X-ray CT apparatus 1 according to a fourth embodiment will be described. In the above-described third embodiment, the case where the X-ray CT apparatus 1 automatically acquires the value "Z1" indicating the spatial resolution required when diagnosing a diagnosis target region has been described. However, in the fourth embodiment, the case where the X-ray CT apparatus 1 automatically acquires the value "Z1" indicating the spatial resolution used in the reconstruction function corresponding to the part to be diagnosed will be described.

In the following description of the fourth embodiment, differences from the third embodiment are mainly described. Specifically, the point that the X-ray CT apparatus 1 automatically acquires the value "Z1" indicating the spatial resolution used in the reconstruction function corresponding to the part to be diagnosed will be mainly described. Further, in the description of the fourth embodiment, the description of the same configuration as that of the third embodiment may be omitted.

First, the reconstruction function will be explained. The reconstruction function is a function used when the reconstruction processing function 444 reconstructs CT image data. When CT image data is reconstructed by the reconstruction processing function 444, a reconstruction function corresponding to the region to be imaged is used.

For example, the reconstruction function used when the imaging target is the lung field (lung field reconstruction function) and the reconstruction function when the imaging target is the abdomen (abdominal reconstruction function) are different. A reconstruction function is used. For example, when diagnosing a lung field, high spatial resolution of CT image data is required. On the other hand, when diagnosing the abdomen, the spatial resolution of the CT image data does not have to be high. Therefore, for example, the spatial resolution of the CT image data reconstructed by the lung field reconstruction function is higher than the spatial resolution of the CT image data reconstructed by the abdomen reconstruction function. As described above, the spatial resolution of CT image data obtained by the reconstruction function differs depending on the region to be imaged.

Next, an example of database used in the fourth embodiment will be described. FIG. 7 is a diagram showing an example of the data structure of the database 62 according to the fourth embodiment. A database 62 shown in the example of FIG. 7 is stored in the memory 41 . The database 62 has a record in which an identifier indicating a reconstruction function corresponding to a part to be diagnosed (a part to be imaged) is associated with a value indicating the spatial resolution of CT image data reconstructed by the reconstruction function. is registered for each reconstruction function.

A record of the database 62 includes items of “reconstruction function” and “value indicating spatial resolution”. Identifiers indicating reconstruction functions are registered in the "reconstruction function" item. The database 62 shown in the example of FIG. 7 contains an identifier "F1" indicating the reconstruction function used when the imaging target is the head, and an identifier "F1" indicating the reconstruction function used when the imaging target is the lung field. F2” is registered in each record. Further, in the database 62, the identifier "F3" indicating the reconstruction function used when the imaging target is the abdomen, and the identifier "F4" indicating the reconstruction function used when the imaging target is the pelvis are registered in each record.

A value (mm) indicating the spatial resolution obtained by the reconstruction function indicated by the identifier registered in the "reconstruction function" item is registered in the "value indicating spatial resolution" item. Specifically, in the "value indicating spatial resolution" item, there is a value indicating the spatial resolution of the CT image data reconstructed by the reconstruction function indicated by the identifier registered in the "reconstruction function" item. Registered. For example, the first record of the database 62 indicates that the value indicating the spatial resolution obtained by the reconstruction function used when the imaging target is the head is "A1" (mm). The same applies to other records.

Then, in the fourth embodiment, the determination function 443 executes the processing described below instead of the processing in steps S201 and S202 of the second embodiment. For example, the determination function 443 first acquires an identifier indicating a reconstruction function corresponding to a region to be imaged.

For example, the operator sets various acquisition conditions before projection data is acquired. For example, the operator inputs various collection conditions via the input interface 43 . Various input collection conditions are stored in the memory 41 . At this time, the operator inputs, via the input interface 43, an identifier indicating a reconstruction function corresponding to the part to be imaged as one of the acquisition conditions. As a result, the memory 41 stores an identifier indicating the reconstruction function corresponding to the part to be imaged. A decision function 443 obtains an identifier indicating a reconstruction function stored in memory 41 .

Then, the determination function 443 refers to the database 62 and acquires from the database 62 a value indicating the spatial resolution corresponding to the acquired identifier. To explain with a specific example, the determination function 443 identifies, from all the records in the database 62, the record in which the acquired identifier is registered in the item of “reconstruction function”. Then, the determination function 443 acquires the value registered in the “value indicating spatial resolution” item of the specified record. In the following description, the acquired value is written as "Z1".

Then, the determination function 443 uses the value "Z1" indicating the spatial resolution to execute each process of each step after step S203, as in the second and third embodiments.

The fourth embodiment has been described above. In the fourth embodiment, the memory 41 associates and stores each of the plurality of reconstruction functions and each of the plurality of spatial resolutions. Then, the determination function 443 acquires from the memory 41 the spatial resolution corresponding to the reconstruction function corresponding to the part to be imaged. Then, the determination function 443 determines the matrix size based on the result of comparison between the obtained spatial resolution and the spatial resolution according to the acquisition conditions and the positional relationship described above.

According to the fourth embodiment, as in the second and third embodiments, CT image data with optimum spatial resolution can be reconstructed in optimum reconstruction time. Further, according to the fourth embodiment, similarly to the third embodiment, the value indicating the spatial resolution is automatically acquired without the operator inputting the value indicating the spatial resolution. Therefore, according to the fourth embodiment, as in the third embodiment, CT image data having the optimum spatial resolution can be reconstructed in the optimum reconstruction time while reducing the complexity of the operator. can be done.

(First Modification of First to Fourth Embodiments)
Here, in the first to fourth embodiments, if the once set acquisition conditions are changed by the operator before actually acquiring the projection data, the decision function 443 The matrix size may be determined again according to the acquisition conditions and the positional relationship described above. The reconstruction processing function 444 may then reconstruct the CT image data using the determined matrix size again. Therefore, such a modified example will be described as a first modified example of the first to fourth embodiments.

FIG. 8 is a diagram for explaining a first modification. FIG. 8 illustrates a case where the once set number of views "N1" is changed to "N2" by the operator before actual projection data acquisition. In the example of FIG. 8, the determination function 443 determines the matrix size based on the acquisition condition where only the number of views is changed from "N1" to "N2" and the positional relationship described above.

The first modified example has been described above. In the first modification, the X-ray CT apparatus 1 determines the matrix size according to the changed acquisition conditions even when the acquisition conditions are changed. Therefore, according to the first modification, the matrix size can be determined with high accuracy.

(Second Modification of First to Fourth Embodiments)
Here, in the first to fourth embodiments, the determining function 443 may correct the determined matrix size “B×B” in accordance with the matrix size of the display 42 . The reconstruction processing function 444 may then reconstruct the CT image data using the corrected matrix size. Therefore, such a modified example will be described as a second modified example of the first to fourth embodiments.

FIG. 9 is a diagram for explaining a second modification. FIG. 9 shows the case where the matrix size of the display 42 is "C×D". Here, "D" is a larger natural number than "C". In a second variation, the determining function 443 compares the determined matrix size 'B×B' with the matrix size 'C×D' of the display 42 and determines that the matrix size 'B×B' is the matrix size 'C xD" is determined. For example, decision function 443 determines that matrix size 'B×B' is smaller than matrix size 'C×D' if 'B' is smaller than 'C'. Also, the determination function 443 determines that the matrix size “B×B” is greater than or equal to the matrix size “C×D” when “B” is greater than or equal to “C”.

When determining that the matrix size “B×B” is smaller than the matrix size “C×D”, the decision function 443 changes the matrix size used for reconstruction to “C×C”. In this case, the determination function 443 may change the matrix size used for reconstruction to "DxD". That is, the determination function 443 adjusts the matrix size "C×D" of the display 42 according to the comparison result between the matrix size "C×D" of the display 42 and the determined matrix size "B×B". , to correct the matrix size 'B×B'.

The reconstruction processing function 444 then reconstructs the CT image data using the corrected matrix size “C×C” or “D×D”. That is, the reconstruction processing function 444 reconstructs CT image data with a matrix size of “C×C” or “D×D”.

On the other hand, when determining that the matrix size “B×B” is equal to or larger than the matrix size “C×D”, the determination function 443 does not change the matrix size used for reconstruction as “B×B”. Then, the reconstruction processing function 444 reconstructs the CT image data with a matrix size of “B×B”.

In the second modified example, a case where the matrix size "B×B" is smaller than the matrix size "C×D" will be described. In this case, if the output function 446 displays a CT image representing CT image data with a matrix size of “B×B” on the entire screen of the matrix size of “C×D” of the display 42, the CT image is It is necessary to enlarge the CT image to a matrix size of “C×D” and display it on the display 42 . In this case, since pixels are interpolated, so-called image blurring may occur.

However, in the second modification, when the matrix size "B×B" is smaller than the matrix size "C×D", the matrix size used for reconstruction is either "C×C" or "D×D." Be changed. Therefore, for example, when the matrix size is changed to “C×C”, the output function 446 can display the CT image on the display 42 at the same size without interpolating the pixels. Therefore, the image quality is improved.

The second modification has been described above. In the second modified example, as described above, it is possible to determine the matrix size that provides good image quality according to the display 42 .

(Third Modification of First to Fourth Embodiments)
Here, in the first to fourth embodiments, the case where the determination function 443 determines an arbitrary value as the value of "B" of the matrix size represented by "B×B" is illustrated. . However, decision function 443 may select the value of 'B' from among several candidates. Therefore, such a modified example will be described as a third modified example of the first to fourth embodiments.

In the third modification, the determination function 443 selects a matrix size candidate that is closest to the matrix size "B×B" determined in steps S103, S206, and S210 from a plurality of matrix size candidates. It is determined as the matrix size used for reconstruction. For example, multiple matrix size candidates include four matrix size candidates (“256×256”, “512×512”, “1024×1024” and “2048×2048”).

For example, when the matrix size “B×B” is “1039×1039”, the determination function 443 determines “1024×1024” as the matrix size to be used for reconstruction from among a plurality of matrix size candidates. do. That is, the determination function 443 determines a matrix size according to the above-described acquisition condition and the above-described positional relationship from among a plurality of matrix size candidates.

Note that the determination function 443 selects a matrix size candidate closest to the matrix size “B×B” determined in steps S103, S206, and S210 from among the plurality of matrix size candidates as a new matrix size candidate. Candidates may be determined. Then, the output function 446 may cause the display 42 to display new candidates for the determined matrix size so as to be selectable by the operator. When the operator selects a new matrix size candidate via the input interface 43, the determination function 443 determines the selected new matrix size candidate as the matrix size to be used for reconstruction. good.

The third modification has been described above. According to the third modification, as in the first to fourth embodiments described above, CT image data having optimum spatial resolution can be reconstructed in optimum reconstruction time.

(Fourth Modification of First to Fourth Embodiments)
Here, in the X-ray CT apparatuses 1 according to the first to fourth embodiments, cases where the acquisition conditions and the positional relationships described above are changed have been described. However, in the X-ray CT apparatus 1, of the acquisition conditions and the positional relationship, although the acquisition condition is changed, the positional relationship may remain constant. Therefore, such an X-ray CT apparatus 1 will be described as a fourth modified example.

For example, in the first to fourth embodiments, the case where the determination function 443 determines the matrix size based on the acquisition conditions and the positional relationship has been described. However, in a fourth variant, the decision function 443 decides the matrix size based on the acquisition conditions, as described below.

For example, in the fourth modification, the memory 41 stores a database (not shown). In this database, a record in which a collection condition and a matrix size corresponding to the collection condition are associated and registered is registered for each collection condition. Here, the matrix size registered in the database is the matrix size according to the collection conditions and the constant positional relationship.

Then, the determination function 443 acquires from the memory 41 the acquisition conditions used when acquiring the projection data. Then, the determination function 443 acquires the matrix size corresponding to the acquired acquisition condition from the database, and determines the acquired matrix size as the matrix size to be used for reconstruction. That is, the decision function 443 decides the matrix size based on the collection conditions. The determined matrix size is the matrix size according to the acquisition conditions and the positional relationship, as described above.

In addition, in the fourth modification, the case where the determination function 443 determines the matrix size based on the collection condition has been described. However, the decision function 443 may decide the value 'Z' or 'Z2' indicating the highest spatial resolution based on the acquisition conditions. For example, the memory 41 stores a database (not shown). In this database, a record in which an acquisition condition and a value indicating the spatial resolution corresponding to the acquisition condition are registered in association with each other is registered for each acquisition condition. Here, the value indicating the spatial resolution registered in the database is a value indicating the highest spatial resolution obtained from the acquisition conditions and the constant positional relationship.

Then, the determination function 443 acquires from the memory 41 the acquisition conditions used when acquiring the projection data. Then, the determination function 443 determines the value "Z" or "Z2" indicating the spatial resolution by obtaining the value "Z" or "Z2" indicating the spatial resolution corresponding to the obtained acquisition condition from the database.

The fourth modification has been described above. According to the fourth modification, as in the first to fourth embodiments described above, CT image data having optimum spatial resolution can be reconstructed in optimum reconstruction time.

In each of the embodiments and modifications described above, cases where the X-ray CT apparatus 1 executes various types of processing have been described. However, the same processing as that executed by the X-ray CT apparatus 1 can be performed by radiological diagnostic apparatuses such as an X-ray angiography apparatus, a PET (Positron Emission computed tomography) apparatus, and a SPECT (Single Photon Emission Computed Tomography) apparatus. may be executed.

For example, an X-ray angiography machine performs three-dimensional reconstruction. An X-ray angiography device comprises an X-ray tube, a C-arm, an X-ray detector, and a console device. The C-arm holds the X-ray tube and the X-ray detector so that the distance between the X-ray tube and the X-ray detector (Source Image receptor Distance (SID)) can be changed. The ray detector is arranged to face the subject with the C-arm interposed therebetween, and the X-ray detector detects X-rays emitted from the X-ray tube and transmitted through the subject. The detector transmits detection data to the console device, the x-ray tube, C-arm and x-ray detector of the x-ray angiography device are examples of acquisition units, and the detection data is an example of data.

The console device of the X-ray angiography apparatus has functions similar to the preprocessing function 442, determination function 443, reconstruction processing function 444, image processing function 445 and output function 446 described above. Therefore, the console device of the X-ray angiography apparatus performs the same processing as the console device 40 of the X-ray CT apparatus 1 described above. A console device of an X-ray angiography device is an example of a reconstruction device.

Also, the PET apparatus includes a gantry device and a console device. A pedestal device of a PET device is an example of a collection unit. A PET device console device is an example of a reconstruction device.

The gantry of the PET apparatus comprises a plurality of detector modules and counting information acquisition circuitry. The detector module detects a pair of gamma rays emitted when positrons emitted within the subject combine with electrons to annihilate, and outputs an electrical signal based on the detected pair of gamma rays. A plurality of detector modules are arranged so as to surround the subject in a ring shape. The detector module converts gamma rays emitted from within the subject into light and converts the converted light into electrical signals. The detector module is a photon-counting, Anger-type detector, and has a plurality of scintillators and a plurality of photomultiplier tubes (PMTs).

A scintillator converts a pair of gamma rays emitted when positrons emitted within a subject combine with electrons and annihilate into scintillation photons (optical photons), and outputs scintillation photons. The scintillators are arranged two-dimensionally.

The photomultiplier tube multiplies the scintillation photons output from the scintillator and converts them into electrical signals.

In this way, the detector module converts pair annihilation gamma rays emitted from inside the subject into scintillation photons by the scintillator, converts the converted scintillation photons into electrical signals by the photomultiplier tube, and outputs the electrical signals. That is, the detector module is an indirect conversion type detector.

The counting information collection circuit generates counting information from the output signal of the detector module and transmits the generated counting information to the console device.

The console device of the PET device reconstructs the PET image data based on the counting information transmitted from the gantry device. PET image data is an example of image data. Also, the console device of the PET apparatus has functions similar to the determination function 443, the reconstruction processing function 444 and the output function 446 described above. Therefore, the console device of the PET apparatus performs processing similar to that of the console device 40 of the X-ray CT apparatus 1 described above. For example, the console unit of the PET apparatus calculates the value "Z" or "Z2" indicating the highest spatial resolution obtained from the distance between the radiation source and the detector module, the distance between two adjacent scintillators, etc. do.

The SPECT device has a gantry device and a console device. The gantry of the SPECT device is an example of a collector. The console device of the SPECT device is an example of a reconstruction device.

A pedestal device of a SPECT device is a device that collects projection data by detecting gamma rays emitted from a radiopharmaceutical that is administered to a subject and selectively incorporated into the body tissue of the subject. The gantry has a gamma camera.

The gamma camera has imaging elements arranged two-dimensionally, and two-dimensionally captures the intensity distribution of gamma rays emitted from radiopharmaceutical nuclides (RI: Radio Isotopes) that are selectively incorporated into the living tissue of the subject. to detect. A gamma camera is a device that generates projection data by, for example, amplifying and A/D converting the detected two-dimensional gamma ray intensity distribution data. The gamma camera transmits the generated projection data to the console device. Projection data is an example of data.

The console device of the SPECT device reconstructs nuclear medicine image data (SPECT image data), which is a tomographic image showing the biodistribution of the radiopharmaceutical administered to the subject, from the projection data collected by the gantry device. SPECT image data is an example of image data. Also, the console device of the SPECT device has functions similar to the determination function 443, the reconstruction processing function 444, and the output function 446 described above. Therefore, the console device of the SPECT apparatus performs the same processing as the console device 40 of the X-ray CT apparatus 1 described above. For example, the console device of the SPECT device calculates the value "Z" or "Z2" indicating the highest spatial resolution obtained from the distance between the radiation source and the gamma camera, the distance between two adjacent imaging elements, etc. do.

Each component of each device according to the above-described embodiments is functionally conceptual, and does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution/integration of each device is not limited to the illustrated one, and all or part of them can be functionally or physically distributed/integrated in arbitrary units according to various loads and usage conditions. Can be integrated and configured. Furthermore, all or any part of each processing function performed by each device can be implemented by a CPU and a program analyzed and executed by the CPU, or implemented as hardware based on wired logic.

Also, various processes described in the above-described embodiments can be realized by executing a prepared program on a computer such as a personal computer or a workstation. This program can be distributed via a network such as the Internet. The program can also be recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, DVD, etc., and executed by being read from the recording medium by a computer.

According to at least one embodiment or modified example described above, image data with optimal spatial resolution can be reconstructed in optimal reconstruction time.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 X-ray CT apparatus 443 Decision function 444 Reconstruction processing function

Claims (10)

a determination unit that determines a matrix size based on a collection condition when data is collected by the collection unit and a positional relationship between a plurality of elements that constitute the collection unit;
a reconstruction processing unit that reconstructs image data of the matrix size using the data;
a reconstruction device. The determination unit determines the matrix size based on the spatial resolution according to the acquisition condition and the positional relationship, and the acquisition range of the data or the reconstruction range of the data. Reconstruction according to claim 1 configuration device. Further comprising a reception unit that receives the first spatial resolution,
The determination unit determines the matrix size based on a comparison result between the first spatial resolution and a second spatial resolution according to the acquisition condition and the positional relationship, The reproduction according to claim 1 configuration device. further comprising a storage unit that associates and stores each of a plurality of parts of the subject and each of a plurality of spatial resolutions;
The determination unit acquires a first spatial resolution corresponding to a site to be imaged from the storage unit, and determines a combination of the first spatial resolution and a second spatial resolution according to the acquisition condition and the positional relationship. 2. The reconstruction apparatus according to claim 1, wherein said matrix size is determined based on a comparison result. further comprising a storage unit that associates and stores each of the plurality of reconstruction functions and each of the plurality of spatial resolutions;
The determination unit obtains from the storage unit a first spatial resolution corresponding to a reconstruction function corresponding to a site to be imaged, and acquires a first spatial resolution corresponding to the acquisition condition and the positional relationship. 2. The reconstruction apparatus according to claim 1, wherein said matrix size is determined based on a result of comparison with two spatial resolutions. The determining unit according to any one of claims 3 to 5, wherein the determination unit determines the matrix size based on the lower spatial resolution of the first spatial resolution and the second spatial resolution. reconstruction device. 7. The determination unit according to any one of claims 1 to 6, wherein, when the collection condition is changed before collecting the data, the matrix size is again determined according to the changed collection condition and the positional relationship. The reconstruction device according to any one of the above. further comprising a display control unit that causes a display unit to display an image representing the image data reconstructed by the reconstruction processing unit;
According to a comparison result between the matrix size of the display unit and the determined matrix size, the determination unit corrects the determined matrix size in accordance with the matrix size of the display unit. 8. The reconstruction device according to any one of 7. 9. The reconstruction apparatus according to claim 1, wherein said determining unit determines a matrix size according to said collection condition and said positional relationship from among a plurality of matrix size candidates. the collection unit;
a reconstruction device according to any one of claims 1 to 9;
A radiological diagnostic device comprising:

Images