JP7177613B2 - X-ray CT device - Google Patents

Description

An embodiment of the present invention relates to an X-ray CT (Computed Tomography) apparatus.

2. Description of the Related Art There are medical image diagnostic apparatuses that generate medical image data in which internal tissue of a subject is imaged. Examples of medical image diagnostic apparatuses include an X-ray CT (Computed Tomography) apparatus and an MRI (Magnetic Resonance Imaging) apparatus. The X-ray CT apparatus irradiates the subject with X-rays and, based on the X-rays detected by the X-ray detector, produces two-dimensional image data of the subject's axial tomography and three-dimensional image data based on volume data. Generate as image data.

In an X-ray CT apparatus, there is a case where an examination is performed in which two acquisition modes are combined with one scan mode to perform two CT scans for two scan types. In that case, after setting the scan mode, the first acquisition mode, and the scan parameters (including scanography) and executing the first scan, the scan mode, the second acquisition mode, and the scan parameters (including scanography) are set. ) are respectively set and the second scan is performed.

JP 2016-140660 A

The problem to be solved by the present invention is to reduce the burden on a subject in an examination in which a plurality of scans according to a plurality of scan types are performed.

An X-ray CT apparatus according to an embodiment has an X-ray generation unit, an X-ray detection unit, a setting unit, and an execution unit. The X-ray generator generates X-rays to irradiate a subject. The X-ray detection unit includes a plurality of detection elements for detecting X-rays, and a plurality of detection element arrays in the column direction, each of which is composed of a plurality of detection elements arranged in the channel direction. The setting unit selects and sets two or more scan types from a plurality of scan types each including a combination of a scan mode and an acquisition mode stored in the storage unit. After setting scan parameters related to two or more scan types, the execution unit controls the X-ray generation unit and the X-ray detection unit to execute two or more scans related to the two or more scan types. do.

1 is a schematic diagram showing the configuration of an X-ray CT apparatus according to an embodiment; FIG. FIG. 2 is a diagram showing a configuration example of pixel arrangement of an X-ray detector provided in the X-ray CT apparatus according to the embodiment; FIG. 3 is a diagram showing a usage example of a detectable area of an X-ray detector according to acquisition modes in the X-ray CT apparatus according to the embodiment; FIG. 4 is a diagram showing the concept of element groups formed by grouping a certain number of a plurality of detection elements that constitute an X-ray detector in the X-ray CT apparatus according to the embodiment; FIG. 5 is a block diagram showing an addition unit that performs addition for each element group in the X-ray CT apparatus according to the embodiment; FIG. 6 is a block diagram showing functions of the X-ray CT apparatus according to the embodiment; FIG. 7 is a diagram showing an example of a scan type table in the X-ray CT apparatus according to the embodiment; FIG. 8 is a flowchart showing the operation of the X-ray CT apparatus according to the embodiment; FIG. 9 is a diagram showing, as a flow chart, operations in a first example of a plurality of scan types in the X-ray CT apparatus according to the embodiment; FIG. 10 is a diagram showing, as a flowchart, operations in a second example of a plurality of scan types in the X-ray CT apparatus according to the embodiment; FIG. 11 is a flowchart showing operations in a third example of a plurality of scan types in the X-ray CT apparatus according to the embodiment; FIG. 12 is a diagram showing, as a flowchart, operations in a fourth example of a plurality of scan types in the X-ray CT apparatus according to the embodiment;

Hereinafter, embodiments of the X-ray CT apparatus will be described in detail with reference to the drawings.

In addition, the data acquisition method by the X-ray CT apparatus includes a rotation/rotation (RR: Rotate/Rotate) method in which the X-ray source and the X-ray detector rotate around the subject as a unit, and a ring-shaped method. There are various schemes such as the Stationary/Rotate (SR) scheme in which a large number of detector elements are arrayed in the X-ray tube and only the X-ray tube rotates around the subject. The present invention can be applied to any method. In the following, the X-ray CT apparatus according to the embodiment will be described by taking as an example a case where the rotation/rotation method of the third generation, which is currently the mainstream, is adopted.

FIG. 1 is a schematic diagram showing the configuration of an X-ray CT apparatus according to an embodiment.

FIG. 1 shows an X-ray CT apparatus 1 according to an embodiment. The X-ray CT apparatus 1 includes a gantry device 10 , a bed device 30 and a console device 40 . The gantry device 10 and the bed device 30 are installed in an examination room. The gantry device 10 collects X-ray detection data regarding a subject (for example, a patient) P placed on the bed device 30 . On the other hand, the console device 40 is installed in a control room adjacent to the examination room, generates multidirectional projection data based on multidirectional detection data, and reconstructs a CT image based on the multidirectional projection data. indicate.

The gantry device 10 includes an X-ray tube 11, an X-ray detector 12, a data acquisition circuit (DAS: Data Acquisition System) 13, a rotating frame 14, an X-ray high voltage device 15, a controller 16, a wedge 17, and a collimator 18. Prepare.

The X-ray tube 11 is provided on a rotating frame 14 . The X-ray tube 11 is a vacuum tube that emits thermal electrons from a cathode (filament) toward an anode (target) by applying a high voltage from an X-ray high voltage device 15 . In addition, in the embodiment, both a single-tube type X-ray CT apparatus and a so-called multi-tube type X-ray CT apparatus in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating ring. Applicable.

Note that the X-ray source that generates X-rays is not limited to the X-ray tube 11 . For example, instead of the X-ray tube 11, a focus coil for converging the electron beam generated from the electron gun, a deflection coil for electromagnetic deflection, and a target surrounding half the circumference of the patient P and generating X-rays by collision of the deflected electron beam. X-rays may be generated by a fifth generation system that includes a ring. Also, the X-ray tube 11 is an example of an X-ray generator.

The X-ray detector 12 is provided on the rotating frame 14 so as to face the X-ray tube 11 . The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and outputs detection data corresponding to the X-ray dose to the DAS 13 as electrical signals. In the X-ray detector 12, for example, a plurality of detector element arrays each composed of a plurality of detector elements are arranged in the column direction (slice direction, row direction) along one circular arc centering on the focal point of the X-ray tube. have a structure.

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, and each scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays. The grid has an X-ray shielding plate arranged on the surface of the scintillator array on the X-ray incident side and having a function of absorbing scattered X-rays. 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.

FIG. 2 is a diagram showing a configuration example of the pixel arrangement of the X-ray detector 12. As shown in FIG.

The X-ray detector 12 shown in FIG. 2 has m (m: a positive integer) in the channel direction, that is, has n (n: a positive integer) detector element rows in the column direction. , that is, arranged in n columns. The number (m) of detection elements forming the detection element array shown in FIG. 2 is for convenience. Therefore, the number of detection elements forming the detection element array is not limited to the case shown in FIG. The same applies to the number (n) of detection element arrays arranged in the channel direction.

FIG. 3 is a diagram showing an example of use of detectable areas of the X-ray detector 12 according to acquisition modes. FIG. 3A is a diagram showing a usage example of the detectable area U of the X-ray detector 12 in the high definition mode "HR". FIG. 3B is a diagram showing a usage example of the detectable area U of the X-ray detector 12 in the standard resolution mode "NR". FIG. 3C is a diagram showing an example of use of the detectable area U of the X-ray detector 12 in the low noise mode "LN".

In an X-ray detector provided with a plurality of detection element arrays composed of detection elements of m channels (shown in FIG. 2), the addition number (bundling number) s of detection data is changed according to the acquisition mode. The addition number s is determined by the addition number component i (i is a positive integer) in the channel direction and the addition number component j (j is a positive integer) in the column direction (s=i×j). FIG. 3A shows a usage example of the detectable area U when the number of additions s is 1 (i×j=1×1) in the high-definition mode “HR”. FIG. 3B shows a usage example of the detectable area U when the number of additions s is 4 (i×j=2×2) in the standard resolution mode “NR”. FIG. 3C shows a usage example of the detectable area U when the number of additions s is 16 (i×j=4×4) in the low noise mode “LN”.

As shown in FIG. 3A, the detectable area U of the X-ray detector 12 consists of a first area (detection area) V in which the high-definition mode is performed and a second area (non-detection area). are categorized. The detection area V includes r pixels corresponding to the r detection element columns. Each detector element row in the detection area V includes m pixels corresponding to m channels of detector elements. On the other hand, the non-detection area includes nr pixels corresponding to nr detector element columns. Each detector column in the non-detection area contains m pixels corresponding to m channels. r is a positive integer and r<n. In the high-definition mode, detection data of m×r detection elements included in r detection element arrays are output as detection data of m×r pixels without being added. That is, according to FIG. 3A, in the detection area V, a high-definition reconstructed image can be generated.

As shown in FIGS. 3B and 3C, in the case of the standard resolution mode and the low noise mode, m×n detection elements included in all (or part) of the detection element arrays forming the detectable area U In the detection data of the elements (illustrated in FIG. 2), the detection data of adjacent s(i×j) detection elements are added (bundled). The detectable area U includes n/j pixels corresponding to the n rows of detector elements. Each detector element row in the detection area V includes m/i pixels corresponding to m channels of detector elements. As a result, detection data of m×n/s pixels are output. FIG. 3B shows a case where the number s of detection data to be added is four, and a plurality of detection elements corresponding to a plurality of detection data to be added are arranged with four detection elements adjacent in the channel direction and column direction. indicates when That is, according to FIG. 3(B), the resolution can be lowered and the noise can be reduced as compared with the high-definition mode shown in FIG. 3(A).

FIG. 3C shows a case where the number s of detection data to be added is 16, and a plurality of detection elements corresponding to a plurality of detection data to be added are arranged with 16 detection elements adjacent in the channel direction and column direction. indicates when That is, according to FIG. 3C, compared with the case of the standard resolution mode shown in FIG. 3B, the resolution can be lowered to reduce noise.

Returning to the description of FIG. 1, the DAS 13 is provided on the rotating frame 14 . Under the control of the controller 16, the DAS 13 includes an amplifier that amplifies the electrical signal output from each X-ray detection element of the X-ray detector 12, and converts the electrical signal into a digital signal under the control of the controller 16. It has an A/D (Analog to Digital) converter for converting into a signal, and generates detection data after amplification and digital conversion. Detection data generated by DAS 13 is transferred to console device 40 .

Here, the detection data generated by the DAS 13 is transmitted from a transmitter provided on the rotating frame 14 to a receiver provided on a non-rotating portion of the gantry 10, for example, a fixed portion (not shown), by non-contact data transmission. , is transferred to the console device 40 . The method of transmitting the detection data from the rotating frame 14 to the non-rotating portion of the gantry 10 is not limited to the optical communication described above, and any method of non-contact data transmission may be employed. A fixed portion (not shown) is a frame that rotatably supports the rotating frame 14 .

FIG. 4 is a diagram showing the concept of element groups formed by grouping a certain number of a plurality of detection elements that constitute the X-ray detector 12 . FIG. 5 is a block diagram showing an addition unit that performs addition in element group units.

FIG. 4 shows the k-th (k: positive integer) element group Gk in the detection area V among the plurality of element groups formed in the detection area U shown in FIG. Each element group corresponds to a plurality of detection elements constituting the X-ray detector 12, for example, 16 detection elements D each having four detection elements in the channel direction and four detection elements in the column direction. Note that each element group is not limited to the case of having 16 detection elements, and may have, for example, 4 or 32 detection elements. Also, the shape of each element group, which is determined by the number of detection elements in the channel direction and the row direction, does not have to be square.

FIG. 5 shows the adder A. FIG. The adder A includes 16 switches (for example, switches) 51k connected to each of the 16 detection elements belonging to the k-th element group Gk, an integration circuit 52k belonging to the k-th element group Gk, and a k-th element group Gk. and a switching control circuit 53k belonging to the element group Gk. That is, one integrating circuit 52k and one switching control circuit 53k are provided for each element group.

The switching control circuit 53k is also connected to the 16 switches 51k belonging to the k-th element group Gk via signal lines. It is assumed that the 16 switches 51k of the adder A are provided in the X-ray detector 12, and the integration circuit 52k and the switching control circuit 53k of the adder A are provided in the DAS 13. is not limited to Further, the DAS 13 includes an A/D (Analog to Digital) conversion circuit 181 connected to the integration circuits belonging to all the element groups including the k-th element group Gk in the subsequent stage of the integration circuit 52k.

The integration circuit 52k reads electrical signals from the 16 detection elements belonging to the k-th element group Gk through the 16 switches 51k, and integrates the electrical signals over a predetermined period. The predetermined period is set according to the period of one view.

The switching control circuit 53k controls connection and disconnection of the 16 switches 51k belonging to the k-th element group Gk under the control of the control device 16. FIG. Specifically, the switching control circuit 53k establishes connections between the 16 switches 51k belonging to the k-th element group Gk and the integrating circuits 52k for the high definition mode and for the standard resolution mode. 16 switches 51k are individually controlled to switch between connections or connections for low noise nodes.

When the acquisition mode is the high-definition mode (addition number s=1), the switching control circuit 53k opens and closes the 16 switches 51k belonging to the k-th element group Gk at different timings, so that the integration circuit 52k Electric signals are read out at different timings from the 16 detection elements belonging to the k-th element group Gk. That is, when the acquisition mode is the high-definition mode, the switching control circuit 53k controls the 16 switches 51k to read 16 electrical signals from the 16 detection elements belonging to the k-th element group Gk.

When the acquisition mode is the standard resolution mode (addition number s=4), the switching control circuit 53k classifies the 16 detection elements belonging to the k-th element group Gk into four sets. (1) The switching control circuit 53k substantially simultaneously opens and closes all of the four switches 51k corresponding to the four detection elements belonging to each set. and (2) the switching control circuit 53k opens and closes the switches 51k belonging to different sets at different timings. to read out the electrical signals respectively. That is, when the acquisition mode is the standard resolution mode, the switching control circuit 53k controls the 16 switches 51k to read out 4 electric signals from the 16 detection elements belonging to the k-th element group Gk.

When the acquisition mode is the low noise mode (the number of additions s=16), the switching control circuit 53k opens and closes all the 16 switches 51k belonging to the k-th element group Gk substantially simultaneously, so that the integrating circuit 52k , electric signals are read out substantially simultaneously from the 16 detection elements belonging to the k-th element group Gk. That is, when the acquisition mode is the low noise mode, the switching control circuit 53k controls the 16 switches 51k so as to read one electric signal from the 16 detection elements belonging to the k-th element group Gk.

As shown in FIG. 5, the A/D converter 181 A/D-converts integrated signals from a plurality of integration circuits to generate pure raw data before preprocessing such as logarithmic conversion. Preprocessing is performed on pure raw data to generate raw data before reconstruction processing. Any number of integration circuits may be connected to the A/D converter 181 . Typically, one A/D converter 181 is connected to a predetermined number of integration circuits. However, embodiments are not so limited. One A/D converter 181 may be connected to one integration circuit.

Returning to the description of FIG. 1, the rotating frame 14 is a rotating portion that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. The rotating frame 14 is an annular frame that rotates the X-ray tube 11 and the X-ray detector 12 together under the control of a control device 16, which will be described later. In addition to the X-ray tube 11 and the X-ray detector 12, the rotation frame 14 further includes and supports the DAS 13 and the X-ray high voltage device 15. At least one of them may be supported by a fixed frame (not shown) that is a fixed part that rotatably supports the rotating frame 14 .

In this manner, the X-ray CT apparatus 1 rotates around the patient P the rotating frame 14 that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. , 360 degrees of detection data of the patient P are collected. Note that the CT image reconstruction method is not limited to the full-scan reconstruction method using detection data for 360°. For example, the X-ray CT apparatus 1 may employ a half-reconstruction method for reconstructing a CT image based on detection data for half a circle (180°)+fan angle.

The X-ray high voltage device 15 has electric circuits such as a transformer and a rectifier. The X-ray high voltage device 15 is controlled by a high voltage generator (not shown) having a function of generating a high voltage to be applied to the X-ray tube 11 under the control of the control device 16, which will be described later, and the control device 16, which will be described later. , there is an X-ray control device (not shown) for controlling the output voltage according to the X-rays emitted by the X-ray tube 11 . The high voltage generator may be of a transformer type or an inverter type.

The controller 16 has a processor and memory, and drive mechanisms such as motors and actuators. The configuration of the processing circuit and memory is the same as that of the processing circuit 44 and memory 41 of the console device 40, which will be described later, and therefore the description thereof is omitted.

The control device 16 receives an input signal from the input interface 43 of the console device 40 or an operation panel (not shown) attached to the gantry device 10, and has a function of controlling the operations of the gantry device 10 and the bed device 30. have. For example, the control device 16 receives an input signal and performs control to rotate the rotating frame 14 , control to tilt the gantry device 10 , and control to operate the bed device 30 and the tabletop 33 . Note that the control for tilting the gantry device 10 is performed by the control device 16 based on tilt angle (tilt angle) information input from an operation panel attached to the gantry device 10, so as to tilt the rotating frame 14 about an axis parallel to the X-axis direction. This is achieved by rotating the Note that the control device 16 may be provided in the gantry device 10 or may be provided in the console device 40 .

Further, the control device 16 controls the angle of the X-ray tube 11 and the operation of the wedge 17 and the collimator 18, which will be described later, based on the imaging conditions input from the console device 40 or the operation panel attached to the gantry device 10. .

A wedge 17 is provided on the rotating frame 14 so as to be arranged on the X-ray emission side of the X-ray tube 11 . Wedge 17 is a filter for adjusting the dose of X-rays emitted from X-ray tube 11 under the control of controller 16 . Specifically, the wedge 17 is a filter that transmits and attenuates the X-rays emitted from the X-ray tube 11 so that the X-rays emitted from the X-ray tube 11 to the patient P have a predetermined distribution. is. For example, the wedge 17 (wedge filter, bow-tie filter) is a filter made of aluminum so as to have a predetermined target angle and a predetermined thickness.

The collimator 18 is also called an aperture or a slit, and is provided on the rotating frame 14 so as to be arranged on the X-ray emission side of the X-ray tube 11 . The collimator 18 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 17 under the control of the control device 16, and forms an X-ray irradiation aperture by combining a plurality of lead plates or the like. Note that a collimator (not shown) other than the collimator 18 may also be provided in the preceding stage of the wedge 17 .

The bed device 30 includes a base 31 , a bed driving device 32 , a top plate 33 and a support frame 34 . The bed device 30 is a device on which the patient P to be scanned is placed and which is moved under the control of the control device 16 .

The base 31 is a housing that supports the support frame 34 so as to be movable in the vertical direction (y-axis direction). The bed driving device 32 is a motor or actuator that moves the table 33 on which the patient P is placed in the longitudinal direction (z-axis direction) of the table 33 . The top plate 33 provided on the upper surface of the support frame 34 is a plate having a shape on which the patient P can be placed.

Note that the bed driving device 32 may move the support frame 34 in addition to the top plate 33 in the long axis direction (z-axis direction) of the top plate 33 . Further, the bed drive device 32 may move the base 31 of the bed device 30 together. When the present invention is applied to standing CT, a method of moving a patient moving mechanism corresponding to the top plate 33 may be used. In addition, when performing imaging involving a relative change in the positional relationship between the imaging system of the gantry device 10 and the tabletop 33, such as helical scanning or scano (scout) imaging for positioning, etc., the relative positional relationship Such a change may be performed by driving the top plate 33, by running the fixed portion of the gantry device 10, or by combining them.

In the embodiment, the longitudinal direction of the rotational axis of the rotating frame 14 or the top plate 33 of the bed device 30 in the non-tilt state is the z-axis direction, and the axial direction perpendicular to the z-axis direction and horizontal to the floor surface is the z-axis direction. An axial direction perpendicular to the x-axis direction and the z-axis direction and perpendicular to the floor surface is defined as a y-axis direction.

Console device 40 includes memory 41 , display 42 , input interface 43 , and processing circuitry 44 . In the following description, it is assumed that the console device 40 executes all functions with a single console, but these functions may be executed with a plurality of consoles.

The memory 41 is, 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, and has a configuration including a recording medium readable by a processor. The memory 41 stores a scan type table (shown in FIG. 7) indicating a plurality of scan types each consisting of a combination of scan modes and collection modes.

Detection data generated by the X-ray CT apparatus 1 and projection data and reconstructed image data, which will be described later, may be stored in the memory 41 . Further, detection data, projection data, and reconstructed image data generated by the X-ray CT apparatus 1 are stored in external sources such as image servers that can be connected to the X-ray CT apparatus 1 via a network such as a LAN (Local Area Network). It may be stored in a storage device. Similarly, part or all of the programs and data in the recording medium of the memory 41 may be downloaded by communication via a network, or given to the memory 41 via a portable storage medium such as an optical disk. good.

The display 42 displays various information. For example, the display 42 outputs a medical image (CT image) generated by the processing circuit 44, a GUI (Graphical User Interface) for receiving various operations from the user, and the like. For example, the display 42 is a liquid crystal display, a CRT (Cathode Ray Tube) display, an OLED (Organic Light Emitting Diode) display, or the like.

The input interface 43 includes a circuit for inputting signals from an input device that can be operated by an operator, and an input device. Input devices include trackballs, switches, mice, keyboards, touchpads that perform input operations by touching the scanning surface, touch screens that integrate display screens and touchpads, non-contact input circuits using optical sensors, and an audio input circuit or the like. When the operator operates the input device, the input interface 43 generates an input signal according to the operation and outputs it to the processing section 21 .

The processing circuit 44 is a processor that controls the overall operation of the X-ray CT apparatus 1 by reading and executing programs stored in the memory 41 . The processing circuit 44 performs preprocessing such as correction processing on the detection data output from the data acquisition circuit 14 to generate projection data. Further, the processing circuit 44 performs reconstruction processing on the projection data to generate two-dimensional image data of axial tomography and three-dimensional image data based on volume data as CT image data. Volume data is a set of voxel data having CT value distribution information in a three-dimensional space. The processing circuit 44 generates volume data based on two-dimensional image data of a plurality of axial tomograms, thereby converting image data of an arbitrary tomogram (MPR: Multi-Planar Reconstruction) and projection image data viewed from an arbitrary direction into three types. Generate as dimensional image data. Projection image data is obtained by subjecting volume data to volume rendering processing or surface rendering processing.

Next, the functions of the X-ray CT apparatus 1 will be specifically described.
FIG. 6 is a block diagram showing functions of the X-ray CT apparatus 1. As shown in FIG.

The X-ray CT apparatus 1 implements a scan type setting function 61, a scan execution function 62, and an image generation function 63 by the processor of the processing circuit 44 executing the programs. Although the functions 61 to 63 function as software will be described as an example, all or part of the functions 61 to 63 are provided in the X-ray CT apparatus 1 as hardware such as ASIC. may Also, all or part of the functions 61 to 63 may be included in the control device 16 .

The memory 41 pre-stores (presets) a plurality of scan types (for example, the scan type table shown in FIG. 7) consisting of combinations of scan modes and acquisition modes. The scan type setting function 61 includes a function of selecting and setting a predetermined plurality of scan types from among a plurality of scan types each consisting of a combination of a scan mode and an acquisition mode stored in the memory 41 . A scan mode is also called a protocol. For example, the scan type setting function 61 selects a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 by the operator via the input interface 43, thereby setting a plurality of scan types. Set the scan type. Also, the scan type setting function 61 is an example of a setting unit.

FIG. 7 is a diagram showing an example of a scan type table.
As shown in FIG. 7, the scan type consists of a combination of scan mode and acquisition mode. Three acquisition modes are supported for each scan mode: high definition mode, standard resolution mode, and low noise mode.

Scan modes include volume scan, dynamic volume scan, helical scan, and the like. Volume scanning refers to scanning for one time phase using the X-ray detector 12 having a plurality of detector element arrays without changing the positional relationship between the gantry 10 and the tabletop 12 . A dynamic volume scan is a multi-phase scan performed without changing the positional relationship between the gantry 10 and the tabletop 12 using the X-ray detector 12 having one or more detector element arrays. Helical scanning is performed by using an X-ray detector 12 having one or a plurality of detector element arrays, and moving the top plate 12 against the gantry device 10 or the gantry device 10 against the top plate 12 in the z-axis direction. Scanning that is performed while moving to

Acquisition modes include high definition mode, standard definition mode, low noise mode, and the like. The high-definition mode is a mode in which the detection data of the m×r detection elements forming the X-ray detector 12 are not added and output from the adder A as the detection data of m×r pixels (FIG. 3). (A)). The standard resolution mode and the low noise mode are obtained by adding the detection data of the m×n detection elements constituting the X-ray detector 12 with the number of additions s to obtain m×n/s data, that is, (m/i )×(n/j) pixels are output from the adder A (shown in FIGS. 3B and 3C).

By selecting a plurality of scan types from the scan type table shown in FIG. 7, a plurality of different scan types can be handled as one scan. can be temporarily set.

Returning to the description of FIG. 6 , the scan execution function 62 includes a function of setting scan parameters for each of the multiple scan types set by the scan type setting function 61 . For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 . Scan parameters include scan area, focus size, helical pitch (for helical scan), X-ray output (tube voltage, tube current, etc.), scan speed, view rate, beam width, and the like.

In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram.

Further, the scan executing function 62 controls the X-ray tube 11 and the like via the control device 16 after setting the scan parameters related to the plurality of scan types set by the scan type setting function 61, and performs a plurality of scans. It includes the ability to execute multiple scans of each type. The scan execution function 62 is an example of an execution unit.

The image generation function 63 generates tomographic image data and three-dimensional image data of axial tomography based on the detection data generated according to the scan related to at least one scan type among the plurality of scan types executed by the scan execution function 62. and the like to reconstruct CT image data. The image generation function 63 can also display the CT image data on the display 42 as a CT image. The image generation function 63 can also store CT image data in the memory 41 . The image generation function 63 is an example of a generation unit.

Next, the operation of the X-ray CT apparatus 1 will be explained using the flowchart shown in FIG.

FIG. 8 is a diagram showing the operation of the X-ray CT apparatus 1 as a flowchart. In FIG. 8, numerals attached to "ST" indicate respective steps of the flow chart.

First, the scan type setting function 61 selects and sets a plurality of predetermined scan types from among a plurality of scan types that are combinations of scan modes and collection modes (step ST1). For example, the scan type setting function 61 allows the operator to select a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 via the input interface 43 in step ST1. Set each scan type by In the description of FIG. 8, it is assumed that the first scan type and the second scan type are set as the plurality of scan types.

The scan execution function 62 sets scan parameters for the first and second scan types set in step ST1 (step ST2). For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 in step ST2. In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram.

Further, the scan execution function 62 controls the control device 16 so that the gantry device 10 is set according to the scan parameters of the first scan type set in step ST2, and the scan parameters set in step ST1 are adjusted. A first scan corresponding to the first scan type is executed (step ST4). In step ST4, the scan execution function 62 executes the first scan via the control device 16 while controlling the adder A (shown in FIG. 5) according to the addition number s of the acquisition mode corresponding to the first scan type. do.

When the first scan corresponding to the first scan type is completed, the scan execution function 62 switches the scan type from the first scan type to the second scan type (step ST6). When switching the scan type in step ST6, the scan execution function 62 controls the control device 16 to switch the gantry device 10 adjusted so as to be set according to the scan parameters of the first scan type to the second scan type. according to the scanning parameters of the Specifically, the scan execution function 62 controls the control device 16 to move the table top 33, change the rotational speed of the rotating frame 14, and adjust the focal size according to the start position of the second scan. , change slit settings, collect offsets, and change correction data such as calibration.

The scan execution function 62 executes a second scan corresponding to the second scan type set in step ST1 (step ST7). In step ST7, the scan execution function 62 executes the second scan via the control device 16 while controlling the adder A according to the addition number s of the acquisition mode corresponding to the second scan type.

The image generation function 63 reconstructs CT image data based on detection data generated according to at least one of the first scan performed in step ST4 and the second scan performed in step ST6. , the CT image data is displayed on the display 42 as a CT image (step ST8).

The image generation function 63 stores the CT image data generated in step ST8 in the memory 41 (step ST9).

As described above, the X-ray CT apparatus 1 can reduce the burden on the patient P in examinations in which the first scan and the second scan are successively performed. For example, as a comparative example, in an examination in which two acquisition modes are combined with one scan mode to perform two scans, the scan mode, the first acquisition mode, and the scan parameters (including scanography) is set to perform the first scan, the scan mode, second acquisition mode, and scan parameters (including scanography) may be set to perform the second scan. In this case, mode switching takes a long time, so the throughput of the entire examination is low, and the burden on the patient P increases.

In order to solve such a problem, in the X-ray CT apparatus 1, a plurality of scan types (for example, a scan type table shown in FIG. 7) consisting of combinations of scan modes and acquisition modes are set in advance. , the throughput of the entire examination can be improved in the examination in which the first scan and the second scan are continuously performed, thereby reducing the burden on the patient P.

Next, the specific example of FIG. 8 will be described with reference to FIGS. 9 to 12. FIG.

(First specific example)
FIG. 9 is a diagram showing, as a flowchart, the operation in the first example of multiple scan types. In FIG. 9, numerals attached to "ST" indicate respective steps of the flow chart.

The flowchart shown in FIG. 9 relates to an imaging examination of the chest or the like employing Real Prep. Here, the first scan is assumed to be a provisional scan for real preparation, and the second scan is assumed to be a main scan for generating an image for diagnosis. In that case, the X-ray CT apparatus 1 generates a non-contrast image (for example, a scan image) of the patient P in a non-contrast state, sets an ROI (Region Of Interest) and a threshold based on the non-contrast image, start the injection of After starting the injection of the contrast agent, the X-ray CT apparatus 1 starts temporary scanning for real prep. Realprep detects the start timing (trigger) of the main scan before the main scan such as dynamic scan, and starts the main scan when the CT value (or luminance value) in the ROI exceeds the threshold. be.

First, the scan type setting function 61 sets the first scan type "standard resolution" by combining the dynamic volume scan "DV" as the scan mode with the standard resolution mode "NR" and the high-definition mode "HR" as acquisition modes. Dynamic Volume Scan: NR-DV” and the second scan type “High-definition Dynamic Volume Scan: HR-DV” are selected and set (step ST21). For example, the scan type setting function 61 allows the operator to select a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 via the input interface 43 in step ST21. Set each scan type by

The scan execution function 62 sets scan parameters for the first scan type "NR-DV" and the second scan type "HR-DV" set in step ST21 (step ST22). For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 in step ST22. In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram.

The scan execution function 62 controls the control device 16 to adjust the setting of the gantry device 10 according to the scan parameters of the first scan type “NR-DV” set in step ST22, and starts imaging. Then, real prep is started (step ST23). The scan executing function 62 controls the control device 16 to execute the first scan "NR-DV" corresponding to the first scan type "NR-DV" set in step ST21 (step ST24). In step ST24, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=4 shown in FIG. 3B) corresponding to the first scan type "NR-DV" While controlling the adder A, the first scan “NR-DV” is executed.

When the CT value (or luminance value) in the ROI of the non-contrast image exceeds the threshold, the scan execution function 62 ends the first scan "NR-DV" and changes the scan type to the first scan type "NR- DV” to the second scan type “HR-DV” (step ST26). The scan execution function 62 controls the control device 16 in step ST26 in the same manner as in step ST6 (shown in FIG. 8).

The scan executing function 62 executes the second scan "HR-DV" corresponding to the second scan type "HR-DV" set in step ST21 (step ST27). In step ST27, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=1 shown in FIG. 3A) corresponding to the second scan type "HR-DV" While controlling the adder A, the second scan "HR-DV" is executed (step ST27).

The image generation function 63 reconstructs high-definition CT image data based on the detection data generated according to the second scan "HR-DV" executed in step ST27, and displays the CT image data as a CT image on the display 42. is displayed (step ST28).

The image generation function 63 stores the volume data obtained in step ST24 and the CT image data generated in step ST28 in the memory 41 (step ST29).

As described above, according to the operation shown in FIG. 9 by the X-ray CT apparatus 1, it is possible to reduce the burden on the patient P in contrast-enhanced examinations of the chest or the like using RealPrep.

(Second specific example)
FIG. 10 is a flowchart showing the operation in the second example of multiple scan types. In FIG. 10, numerals attached to "ST" indicate respective steps of the flow chart.

First, the scan type setting function 61 sets the first scan type "standard resolution volume scan: NR-V", which is a combination of the volume scan "V" as the scan mode and the standard resolution mode "NR" as the acquisition mode, and the scan mode. A second scan type "high-definition helical scan: HR-H", which is a combination of the helical scan "H" as the mode and the high-definition mode "HR" as the acquisition mode, is selected and set (step ST41). For example, the scan type setting function 61 allows the operator to select a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 via the input interface 43 in step ST41. Set each scan type by

The scan execution function 62 sets scan parameters for the first scan type "NR-V" and the second scan type "HR-H" set in step ST41 (step ST42). For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 in step ST42. In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram.

Further, the scan execution function 62 controls the control device 16 so that the gantry device 10 is set according to the scan parameters of the first scan type "NR-V" set in step ST42, and step A first scan "NR-V" corresponding to the first scan type "NR-V" set in ST41 is executed (step ST44). In step ST44, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=4 shown in FIG. 3B) corresponding to the first scan type "NR-V" While controlling the adder A, the first scan "NR-V" is executed.

The image generation function 63 reconstructs the CT image data based on the detection data generated according to the first scan "NR-V" executed in step ST44, and displays the CT image data as a CT image on the display 42. (Step ST45). Here, the scan execution function 62 displays the scan area of the second scan type "HR-H" set in step ST42 on the displayed reconstructed image, so that the operator can, via the input interface, The scan area of the second scan "HR-H" may be finely corrected (reset).

When the first scan "NR-V" corresponding to the first scan type "NR-V" is completed, the scan execution function 62 changes the scan type from the first scan type "NR-V" to the second scan type "HR -H" (step ST46). The scan execution function 62 controls the control device 16 at step ST46 in the same manner as at step ST6 (shown in FIG. 8).

The scan executing function 62 executes the second scan "HR-H" corresponding to the second scan type "HR-H" set in step ST41 (step ST47). In step ST47, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=1 shown in FIG. 3A) corresponding to the second scan type "HR-H" While controlling the adder A, the second scan "HR-H" is executed.

The image generation function 63 reconstructs high-definition CT image data based on the detection data generated according to the second scan "HR-H" executed in step ST47, and displays the CT image data as a CT image on the display 42. is displayed (step ST48). The image generation function 63 can also reconstruct standard resolution CT image data based on the detection data generated according to the second scan "HR-H" executed in step ST47. Methods for adjusting the resolution include a method using a reconstruction function, an image filter, and a method of digital addition (digital bundling) of acquired data.

The image generation function 63 stores the CT image data generated in steps ST45 and ST48 in the memory 41 (step ST49).

As described above, according to the operation shown in FIG. 10 by the X-ray CT apparatus 1, the burden on the patient P is reduced in the examination in which the first scan "NR-V" and the second scan "HR-H" are continuously performed. can be made

(Third specific example)
FIG. 11 is a diagram showing, as a flowchart, the operation in the third example of multiple scan types. In FIG. 11, numerals attached to "ST" indicate respective steps of the flow chart. In addition, in FIG. 11, the case where the whole is divided into three of standard resolution helical scanning, high-definition helical scanning, and standard resolution helical scanning, and mode switching is performed twice will be described. However, the number of divisions and the number of times of switching are not limited to these.

First, the scan type setting function 61 sets the first scan type "standard resolution helical scan" by combining the helical scan "H" as the scan mode with the standard resolution mode "NR" and the high-definition mode "HR" as acquisition modes. Scan: NR-H", second scan type "high-definition helical scan: HR-H", and third scan type "standard resolution helical scan: NR-H'" are selected and set (step ST61 ). For example, the scan type setting function 61 allows the operator to select a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 via the input interface 43 in step ST61. Set each scan type by

The scan execution function 62 sets scan parameters for the first scan type "NR-H", the second scan type "HR-H", and the third scan type "NR-H'" set in step ST61. (step ST62). For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 in step ST62. In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram. The scan execution function 62 may individually set the scan areas for the three scan types, or set the entire scan area (total range of the three scan areas) and the second scan type "HR-H". A method of setting the scan area of .

Further, the scan execution function 62 controls the control device 16 so that the gantry device 10 is set according to the scan parameters of the first scan type "NR-H" set in step ST62, and step A first scan "NR-H" corresponding to the first scan type "NR-H" set in ST61 is executed (step ST64). In step ST64, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=4 shown in FIG. 3B) corresponding to the first scan type "NR-H" While controlling the adder A, the first scan "NR-H" is executed.

The scan execution function 62 moves the tracking collimator toward the end of the first scan "NR-H", toward the joint between the scan area of the first scan "NR-H" and the scan area of the second scan "HR-H". is operated, the helical pitch is gradually lowered, and after the top plate 33 is stopped, X-ray irradiation is stopped and data acquisition is stopped. When the first scan "NR-H" corresponding to the first scan type "NR-H" is completed, the scan execution function 62 changes the scan type from the first scan type "NR-H" to the second scan type "HR -H" (step ST66). The scan execution function 62 controls the control device 16 at step ST66 in the same manner as at step ST6 (shown in FIG. 8).

The scan execution function 62 executes the second scan "HR-H" corresponding to the second scan type "HR-H" set in step ST61 (step ST67). In step ST67, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=1 shown in FIG. 3A) corresponding to the second scan type "HR-H" While controlling the adder A, the second scan "HR-H" is executed.

The scan execution function 62 moves the tracking collimator toward the end of the second scan "HR-H", toward the joint between the scan area of the second scan "HR-H" and the scan area of the third scan "NR-H". is operated, the helical pitch is gradually lowered, and after the top plate 33 is stopped, X-ray irradiation is stopped and data acquisition is stopped. When the second scan "HR-H" corresponding to the second scan type "HR-H" is completed, the scan execution function 62 changes the scan type from the second scan type "HR-H" to the third scan type. Switch to "NR-H'" (step ST76). The scan execution function 62 controls the control device 16 in step ST76 in the same manner as in step ST6 (shown in FIG. 8).

The scan execution function 62 executes the third scan "NR-H'" corresponding to the third scan type "NR-H'" set in step ST61 (step ST77). In step ST77, the scan execution function 62, via the control device 16, sets the acquisition mode addition number s (for example, s=4 shown in FIG. 3B) corresponding to the third scan type "NR-H'". ), the third scan “NR-H′” is executed while controlling the adder A according to the above.

The image generation function 63 reconstructs standard resolution CT image data based on the detection data generated according to the first and third scans "NR-H, NR-H'" executed in steps ST64 and ST77, and , reconstructs high-definition CT image data based on the detection data generated according to the second scan "HR-H" executed in step ST67, and displays the CT image data as a CT image on the display 42 (step ST78).

Further, the image generation function 63 corresponds to the first and third scans "NR-H, NR-H'" based on the detection data generated according to the second scan "HR-H" executed in step ST67. It is also possible to reconstruct standard resolution CT image data having the same image resolution as standard resolution CT image data. In that case, the image generating function 63 connects three pieces of standard resolution CT image data corresponding to the three scan areas related to the first to third scans "NR-H, HR-H, NR-H'". Together, it produces standard resolution volumetric data representing the entire three scan regions.

The image generation function 63 stores the CT image data generated in step ST78 in the memory 41 (step ST79).

As described above, according to the operation shown in FIG. 11 by the X-ray CT apparatus 1, the patient P is burden can be reduced.

(Fourth specific example)
FIG. 12 is a flowchart showing operations in a fourth example of multiple scan types. In FIG. 12, numerals attached to "ST" indicate respective steps of the flow chart. Note that FIG. 12 describes a case where "volume scan" is selected as the collection mode, but the present invention is not limited to this case. For example, in FIG. 12, the acquisition mode may be "dynamic volume scan" instead of "volume scan".

First, the scan type setting function 61 sets the first scan type "standard resolution volume scan" by combining the volume scan "V" as the scan mode with the standard resolution mode "NR" and the high-definition mode "HR" as acquisition modes. : NR-V" and the second scan type "high-definition volume scan: HR-V" are selected and set (step ST81). For example, the scan type setting function 61 allows the operator to select a predetermined scan type from a scan type table (shown in FIG. 7) preset in the memory 41 via the input interface 43 in step ST81. Set each scan type by

The scan execution function 62 sets scan parameters for the first scan type "NR-V" and the second scan type "HR-V" set in step ST81 (step ST82). For example, the scan execution function 62 sets scan parameters according to instructions from the operator via the input interface 43 in step ST82. In general, the scan execution function 62 performs 2D or 3D scanography to generate a scanogram, and sets scan parameters such as a scan area for each scan type based on the scanogram.

Further, the scan execution function 62 controls the control device 16 so that the gantry device 10 is set according to the scan parameters of the first scan type "NR-V" set in step ST82, and step A first scan "NR-V" corresponding to the scan type "NR-V" set in ST81 is executed (step ST84). In step ST84, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=4 shown in FIG. 3B) corresponding to the first scan type "NR-V" While controlling the adder A, the first scan "NR-V" is executed.

The image generation function 63 reconstructs CT image data based on the detection data generated according to the first scan "NR-V" corresponding to the first scan type "NR-V" executed in step ST84, The CT image data is displayed on the display 42 as a CT image (step ST85). Here, the scan execution function 62 displays the scan area of the second scan type "HR-V" set in step ST82 on the displayed reconstructed image, so that the operator can, via the input interface, The scan area of the second scan "HR-V" may be finely corrected (reset).

When the first scan "NR-V" corresponding to the first scan type "NR-V" is completed, the scan execution function 62 changes the scan type from the first scan type "NR-V" to the second scan type " HR-V” (step ST86). The scan execution function 62 controls the control device 16 at step ST86 in the same manner as at step ST6 (shown in FIG. 8).

The scan execution function 62 executes the second scan "HR-V" corresponding to the second scan type "HR-V" set in step ST81 (step ST87). In step ST87, the scan execution function 62, via the control device 16, according to the acquisition mode addition number s (for example, s=1 shown in FIG. 3A) corresponding to the second scan type "HR-V" While controlling the adder A, the second scan "HR-V" is executed.

The image generation function 63 reconstructs high-definition CT image data based on the detection data generated according to the second scan "HR-V" executed in step ST87, and displays the CT image data as a CT image on the display 42. is displayed (step ST88). The image generation function 63 can also reconstruct standard resolution CT image data based on the detection data generated according to the second scan "HR-V" executed in step ST87.

The image generation function 63 stores the CT image data generated in steps ST85 and ST88 in the memory 41 (step ST89).

As described above, according to the operation shown in FIG. 12 by the X-ray CT apparatus 1, the burden on the patient P is reduced in the examination in which the first scan "NR-V" and the second scan "HR-V" are continuously performed. can be made

In the above embodiment, the term "processor" includes, for example, a dedicated or general-purpose CPU (Central Processing Unit) and GPU (Graphics Processing Unit), as well as an application specific integrated circuit (ASIC) and shall mean a circuit such as a programmable logic device. Programmable logic devices include, for example, Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs). The processor implements various functions by reading and executing programs stored in the storage medium.

Further, in the above embodiments, an example of a case where a single processor of the processing circuit realizes each function is shown, but a processing circuit is configured by combining a plurality of independent processors, and each processor realizes each function. good too. Further, when a plurality of processors are provided, a storage medium for storing programs may be provided individually for each processor, or a single storage medium may collectively store programs corresponding to the functions of all processors. good too.

Note that the scan type setting function 61 is an example of a setting unit. The scan execution function 62 is an example of an execution unit. The image generation function 63 is an example of a generation unit.

According to at least one embodiment described above, it is possible to reduce the burden on the subject in an examination in which a plurality of scans related to a plurality of scan types are performed.

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 device 10 Mounting device 11 X-ray tube 12 X-ray detector 13 DAS
16 control device 41 memory 44 processing circuit 61 scan type setting function 62 scan execution function 63 image generation function A adder

Claims (8)

an X-ray generator that generates X-rays to irradiate an object;
an X-ray detection unit comprising a plurality of detection elements for detecting the X-rays, and provided with a plurality of detection element rows arranged in a channel direction in a row direction;
a top plate on which the subject is placed;
a setting unit that selects and sets two or more scan types from a plurality of scan types that are combinations of scan modes and acquisition modes stored in a storage unit;
After setting the scan parameters related to the two or more scan types, respectively, the X-ray generation unit and the X-ray detection unit are controlled to perform two or more scans related to the two or more scan types, respectively. an execution unit that
with
The scan mode includes a scanning method by helical scanning in which volume data is acquired by the X-ray detection unit while moving the top plate, and a non-scan method in which volume data is acquired by the X-ray detection unit without moving the top plate. A mode of operation corresponding to scanning methods including both helical scanning,
The acquisition mode is an operation mode corresponding to a data acquisition method for acquiring detection data with different resolutions by varying the number of additions of signals from adjacent detection elements.
X-ray CT equipment. The scan mode includes, as the non-helical scan, a volume scan that acquires the volume data in one phase without moving the top plate, and a volume scan that acquires the volume data in a plurality of time phases without moving the top plate. a dynamic volume scan to
The X-ray CT apparatus according to claim 1. further comprising a generation unit that reconstructs CT image data based on detection data generated according to at least one of the two or more scans related to the two or more scan types,
The X-ray CT apparatus according to claim 1 or 2 . The execution unit sets two or more scan areas related to the two or more scan types as scan parameters related to the two or more scan types.
The X-ray CT apparatus according to claim 3 . The execution unit resets the scan region related to any one of the two or more scans based on CT image data based on a scan immediately preceding one of the scans.
The X-ray CT apparatus according to claim 4 . The generation unit reconstructs two or more CT image data having the same image resolution based on the detection data generated according to the two or more scans.
The X-ray CT apparatus according to claim 5 . The generating unit connects the two or more CT image data having the same image resolution to generate volume data representing the entire two or more scan regions.
The X-ray CT apparatus according to claim 6 . further comprising the storage unit that stores a scan type table indicating the plurality of scan types;
The setting unit selects and sets the two or more scan types from the scan type table stored in the storage unit.
The X-ray CT apparatus according to any one of claims 1 to 7 .

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