Data processing device, data processing method, and data processing program

Abstract

The present invention comprises a processor which: acquires raw data corresponding to the number of photons in radiation in each of a plurality of energy bands of radiation, acquired by performing imaging which detects, by means of a detector including a plurality of photon-counting detection elements, radiation which has been emitted from a radiation source and which has passed through a subject; produces integrated data by integrating raw data which is from outside a predetermined region of interest and which corresponds to each of the plurality of energy bands; and produces, on the basis of the raw data from inside the region of interest and the integrated data from outside the region of interest, view data to be stored.

Description

Data processing device, data processing method and data processing program

[0001] The present disclosure relates to a data processing device, a data processing method, and a data processing program.

[0002] In recent years, photon counting computed tomography (PCCT) devices have become known as radiography devices equipped with photon counting detectors. Unlike the charge-integration detectors used in conventional computed tomography (CT) devices, photon counting detectors can measure the number of photons of incident radiation in multiple energy bands. This allows for more information to be obtained than with conventional CT devices.

[0003] In such PCCT devices, a method has been proposed in which data representing the number of photons measured in each of a plurality of energy bands (hereinafter referred to as raw data) and integrated data obtained by integrating the raw data on a view-by-view basis are stored (see, for example, Japanese Patent Application Laid-Open No. 2014-014445). Here, the integrated data is data obtained by, for example, weighting and adding the raw data of all energy bands, and represents the total energy of the entire energy range.

[0004] However, because PCCT devices obtain raw data in multiple energy bands, the data volume is larger than that of conventional CT devices. This makes it difficult to secure a place to store the data. Furthermore, a large-capacity recording medium is required to store the data, which incurs costs.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to make it possible to reduce the volume of data acquired in a PCCT device.

[0006] A data processing device according to the present disclosure includes a processor, which acquires raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being obtained by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements; derives integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and derives view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

[0007] In the data processing device according to the present disclosure, the processor may store the view data.

[0008] In addition, in the data processing device according to the present disclosure, the processor may identify the region of interest based on the field of view set when performing imaging.

[0009] In addition, in the data processing device according to the present disclosure, the processor may identify the region of interest based on a region surrounding the subject included in a preliminary image acquired when imaging is performed.

[0010] In addition, in the data processing device according to the present disclosure, the processor may identify the region of interest based on an input of the region of interest by a user.

[0011] The data processing method according to the present disclosure includes a computer performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements, thereby acquiring raw data corresponding to the number of photons of the radiation in each of a plurality of energy bands of the radiation; deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

[0012] The data processing program according to the present disclosure causes a computer to execute the following steps: acquiring raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being acquired by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements; deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

[0013] The technology of the present disclosure may also be applied to a program product.

[0014] According to the present disclosure, the amount of data acquired in a PCCT device can be reduced.

[0015] Schematic configuration diagram of a data processing device according to an embodiment of the present disclosure. Diagram showing the hardware configuration of a data processing device according to this embodiment. Diagram showing the functional configuration of a data processing device according to this embodiment. Diagram showing a display screen of a display for explaining setting of an effective field of view. Diagram for explaining specification of a region of interest. Diagram for explaining specification of a region of interest. Diagram showing specification of a region of interest. Diagram showing raw data and integrated data included in view data. Flowchart showing processing performed in this embodiment. Diagram showing a display screen of a display for explaining setting of a region surrounding a subject. Diagram showing a display screen of a display for explaining setting of a region of interest by an operator.

[0016]

[0023] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. First, an example of the configuration of a medical image capturing system including a control device for a data processing device according to an embodiment of the present disclosure will be described. Fig. 1 is a schematic diagram of the configuration of a medical image capturing system including a data processing device according to this embodiment.

[0017] As shown in Fig. 1, a medical imaging system 1 of this embodiment includes a CT device 2 and a console 3. The CT device 2 includes a gantry 4 and a bed 8. In the following description, the horizontal direction in Fig. 1 is defined as the X-axis, the vertical direction as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis. The CT device 2 is an example of a radiation imaging device.

[0018] The gantry 4 has an opening 4A, and the subject H to be imaged is placed inside the opening 4A while being placed on a bed 8. The gantry 4 and the bed 8 are capable of moving relatively in the Z-axis direction.

[0019] Inside the gantry 4, a radiation source 5 having a radiation tube 6 and a bowtie filter 7, and a detector 9 are arranged facing each other with the subject H in between. The bowtie filter 7 optimizes the radiation exposure by increasing the dose near the center and decreasing the dose on the periphery to reduce the radiation exposure dose in the peripheral area. The radiation emitted from the radiation tube 6 is shaped by the bowtie filter 7 into a beam shape appropriate for the size of the subject H, and is then irradiated onto the subject H.

[0020] The detector 9 detects radiation that has passed through the subject H and generates projection data corresponding to the dose of the detected radiation. As an example, the detector 9 in this embodiment is a photon counting detector in which a plurality of detection elements 9P that detect photon energy, which is the energy of photons of incident radiation, are arranged in an arc shape with the focus of the radiation tube 6 as the center.

[0021] The photon-counting detector measures the energy of each photon and outputs data (hereinafter referred to as raw data) corresponding to the number of radiation photons in each of a plurality of energy bands (also referred to as energy bins). In this embodiment, the detector 9 outputs raw data for, for example, four energy bands. The four energy bands may be, for example, less than 30 keV, 30 keV to less than 50 keV, 50 keV to less than 100 keV, and 100 keV or more, but are not limited to these. The raw data is two-dimensional data in which the detection signal acquired by each of the plurality of detection elements 9P included in the detector 9 is used as the pixel value of each pixel. The detection signal also includes signals for each of the four energy bands.

[0022] In this embodiment, X-rays are used as an example of radiation, but the radiation is not limited to this and gamma rays or the like can also be used.

[0023] The radiation tube 6 and the detector 9 are attached to a rotating plate 4B inside the gantry 4, and are rotated around the subject H by a rotation drive unit (not shown). By repeating the irradiation of radiation from the radiation tube 6 and the detection of radiation by the detector 9 as they rotate, raw data is acquired in units of a plurality of views at different projection angles of radiation onto the subject. The raw data acquired by the detector 9 is output to the console 3.

[0024] The dose of radiation emitted from the radiation tube 6, the rotation speed of the gantry 4, and the relative movement speed between the gantry 4 and the bed 8 are set by the console 3 based on the imaging conditions input by an operator such as a technician.

[0025] The console 3 of this embodiment controls imaging of the subject H, generates tomographic images from data acquired by imaging, and sets data storage, etc. The console 3 is an example of a data processing device of the present disclosure.

[0026] Next, a data processing device according to this embodiment will be described. First, the hardware configuration of the data processing device according to this embodiment, which is included in the console 3, will be described with reference to Fig. 2. As shown in Fig. 2, the data processing device 10 included in the console 3 is a computer such as a workstation, a server computer, or a personal computer, and includes a CPU (Central Processing Unit) 11, non-volatile storage 13, and memory 16 as a temporary storage area.

[0027] The data processing device 10 also includes a display 14, an input device 15, and an I / F (Interface) 17. The CPU 11, the storage 13, the display 14, the input device 15, the memory 16, and the I / F 17 are connected to a bus 18. The CPU 11 is an example of a processor in the present disclosure.

[0028] The storage 13 is realized by a hard disk drive (HDD), a solid state drive (SSD), a flash memory, etc. The storage 13 as a storage medium stores the data processing program 12 installed in the data processing device 10. The CPU 11 reads the data processing program 12 from the storage 13, loads it into the memory 16, and executes the loaded data processing program 12.

[0029] The display 14 is a device that displays various screens, and is, for example, a liquid crystal display or an EL (Electro Luminescence) display.

[0030] The input device 15 is used by the operator to input instructions and various information regarding imaging conditions, image generation and display, etc. when imaging the subject H. Examples of the input device 15 include various switches, buttons, a touch panel, a touch pen, a keyboard, and a mouse. The display 14 and the input device 15 may be integrated into a touch panel display.

[0031] The I / F 17 communicates various types of information with a rotation drive unit (not shown) of the gantry 4, the radiation source 5, and the detector 9 via wired or wireless communication.

[0032] The data processing program 12 is stored in an externally accessible state in a storage device of a server computer connected to a network or in network storage, and is downloaded and installed in response to a request into a computer constituting the data processing device 10. Alternatively, the program is recorded on a recording medium such as a DVD (Digital Versatile Disc) or a CD-ROM (Compact Disc Read Only Memory) and distributed, and is installed into a computer constituting the data processing device 10 from the recording medium.

[0033] Next, the functional configuration of the data processing device according to this embodiment will be described. Fig. 3 is a diagram showing the functional configuration of the data processing device according to this embodiment. As shown in Fig. 3, the data processing device 10 includes an information acquisition unit 21, an imaging control unit 22, a region of interest identification unit 23, an integration unit 24, a derivation unit 25, a storage control unit 26, and a reconstruction unit 27. The CPU 11 executes the data processing program 12 to function as the information acquisition unit 21, the imaging control unit 22, the region of interest identification unit 23, the integration unit 24, the derivation unit 25, the storage control unit 26, and the reconstruction unit 27.

[0034] The information acquisition unit 21 acquires raw data for each view acquired by imaging the subject H from the CT device 2. The imaging of the subject H for acquiring raw data is referred to as the main imaging. In this embodiment, scanogram imaging is performed prior to the main imaging in order to set a field of view (FOV) of the subject H during the main imaging. The scanogram imaging is performed by imaging the subject H with the radiation source 5 and the detector 9 fixed. In this embodiment, a first scanogram image obtained by imaging the subject H from the front and a second scanogram image obtained by imaging the subject H from the side are acquired. The information acquisition unit 21 also acquires image data representing the first and second scanogram images of the subject H acquired by the scanogram imaging from the CT device 2. The first scanogram image and the second scanogram image are examples of preliminary images in the present disclosure.

[0035] The imaging control unit 22 controls each part of the CT apparatus 2 to perform scanogram imaging and actual imaging of the subject H in response to instructions from the input device 15. During scanogram imaging, the bed 8 is moved to the opening 4A of the gantry 4 so that the entire region of the subject H required for diagnosis is imaged. The first and second scanogram images acquired by scanogram imaging are two-dimensional radiation images. The first and second scanogram images are displayed on the display 14. The operator views the scanogram images displayed on the display 14 and uses the input device 15 to set a field of view (FOV) for actual imaging.

[0036] 4 is a diagram showing a display screen of a display for explaining how to set a field of view. As shown in FIG. 4, a first scanogram image 31 and a second scanogram image 32 including the entire body of subject H are displayed on a display screen 30. When setting the field of view, initial fields of view 33 and 34 having initial sizes indicated by dashed lines are displayed at initial positions on the first scanogram image 31 and the second scanogram image 32. The operator then uses the input device 15 to adjust the position and size of the initial fields of view 33 and 34, thereby setting fields of view 35 and 36 on the first scanogram image 31 and the second scanogram image 32.

[0037] The imaging control unit 22 performs the actual imaging of the subject H so that the fields of view 35, 36 set by the operator are included. During the actual imaging, radiation is detected by the detector 9 at each projection angle. Then, raw data corresponding to the number of radiation photons for each of a plurality of energy bands is output from the detector 9 and transmitted to the console 3.

[0038] The region of interest identifying unit 23 identifies a region of interest in the raw data based on the set fields of view 35, 36. FIGS. 5 to 7 are diagrams for explaining the identification of a region of interest. In this embodiment, in the raw data, a region having pixel values ​​based on radiation that has passed through the fields of view 35, 36 set as described above is identified as a region of interest 40, and a region having pixel values ​​based on radiation that has not passed through the fields of view 35, 36 is identified as a region of non-interest 41 outside the region of interest. The region of interest 40 and the region of non-interest 41 are identified in the channel direction of the detector 9, as shown in FIGS. 5 to 7 .

[0039] In this embodiment, radiation is irradiated onto the subject H at various projection angles to perform the actual imaging. Therefore, the region of interest differs depending on the radiation irradiation angle with respect to the subject H. For example, as shown in Fig. 5 , when radiation is irradiated from the front of the subject H, the region of interest 40 and the region of non-interest 41 are specified by a range 35X in the X direction of the field of view 35 of the subject H on the detector 9. Note that Figs. 5 to 7 also show a range 36Y in the Y direction of the field of view 36 of the subject H.

[0040] When radiation is irradiated from the side of the subject H as shown in FIG. 6, the region of interest 40 and the region of non-interest 41 are specified by a range 36Y in the Y direction of the field of view 36 of the subject H on the detector 9.

[0041] Furthermore, when radiation is irradiated obliquely onto the subject H as shown in FIG. 7 , the region of interest 40 and the region of non-interest 41 are identified by either the X-direction range of the field of view 35 of the subject H or the Y-direction range 36X of the field of view 36 on the detector 9, whichever is projected larger.

[0042] The integrator 24 derives the integrated data by integrating the raw data in each of the plurality of energy bands in the region of non-interest 41. In this embodiment, raw data is acquired for each of the four energy bands, and therefore the integrated data is derived by, for example, adding or weighting the four raw data.

[0043] The derivation unit 25 derives view data to be stored based on raw data within the region of interest 40 and integrated data outside the region of interest, i.e., the region of non-interest 41. The view data is data for one projection angle, i.e., one view. FIG. 8 is a diagram showing the distribution of data in the view data. As shown in FIG. 8, the view data V0 includes raw data R0 in the region of interest 40 and integrated data I0 in the region of non-interest 41.

[0044] The storage control unit 26 stores the view data V0 in the storage 13.

[0045] The reconstruction unit 27 acquires view data at a plurality of projection angles from the storage 13, and performs logarithmic transformation and reconstruction processing, etc., to derive a tomographic image.

[0046] Next, the processing performed in this embodiment will be described. Fig. 9 is a flowchart showing the processing performed in this embodiment. First, scanogram imaging is performed in the CT device 2 in response to an instruction from the operator, and the information acquisition unit 21 acquires a scanogram image (step ST1). The scanogram image is displayed on the display 14, and the operator sets a field of view (step ST2). Then, the region of interest identification unit 23 identifies a region of interest based on the set field of view (step ST3).

[0047] Next, the imaging control unit 22 causes the CT device 2 to perform actual imaging, thereby performing actual imaging of the subject H at various projection angles and acquiring raw data (step ST4). The information acquisition unit 21 acquires the raw data transmitted from the CT device 2 (step ST5), and the integrator 24 derives integrated data by integrating the raw data in the region of non-interest (step ST6). Next, the derivation unit 25 derives view data to be stored based on the raw data within the region of interest 40 and the integrated data outside the region of interest, i.e., the region of non-interest 41 (step ST7). The storage control unit 26 then stores the view data in the storage 13 (step ST8), and the process ends.

[0048] In this manner, in this embodiment, the detector 9 derives integrated data by integrating raw data outside the region of interest, and view data is derived based on the raw data within the region of interest and the integrated data outside the region of interest.

[0049] Here, let us assume that the detector 9 has 1,000 detecting elements 9P and the capacity of raw data for one energy band is 1 bit. In this embodiment, raw data is acquired in four energy bands, and if the raw data is to be stored as view data as is, a data capacity of 4×1,000=4,000 bits is required. On the other hand, if the number of detecting elements in the region of interest and the region of non-interest are 500 each, the data capacity of the raw data is 4×500=2,000 bits. On the other hand, if the capacity of the integrated data is 1, the data capacity of the integrated data is 1×500=500 bits. Therefore, the data capacity of one view data is 2,500 bits. Therefore, according to this embodiment, the data capacity of the view data can be significantly reduced.

[0050] Furthermore, since the data volume of the view data can be reduced, the frequency with which the view data acquired by the main imaging is deleted can be reduced, thereby reducing the workload of the operator.

[0051] Furthermore, raw data outside the region of interest is not saved, but integrated data is saved, which allows for deriving tomographic images outside the region of interest, eliminating the need for re-imaging when a diagnosis outside the region of interest is required.

[0052] In the above embodiment, the operator views the scanogram image displayed on the display 14, sets the field of view for the actual imaging, and identifies the region of interest based on the set field of view, but this is not limited to this. As shown in Fig. 10, for example, the region of interest identifying unit 23 may detect regions 37 and 38 surrounding the subject H included in the first scanogram image 31 and the second scanogram image 32, and identify a region of interest 40 and a region of non-interest 41 based on the regions 37 and 38.

[0053] This eliminates the need for the user to specify the field of view, thereby reducing the burden on the user and reducing the data volume of the view data.

[0054] In the above embodiment, in addition to setting the field of view for the scanogram image, the operator may be allowed to set a desired region of interest. For example, as shown in Fig. 11, the operator may be allowed to set regions of interest 51 to 53 and 54 to 56 for the head, chest, abdomen, and lower limbs, respectively, for the first scanogram image 31 and the second scanogram image 32 by operating the input device 15.

[0055] When the regions of interest are set in this manner, for example, in the first scanogram image 31 of the subject H shown in Fig. 11, if the raw data includes the boundary between the regions of interest 51 and 52, the data volume of the view data can be reduced not only in the channel direction of the detector 9 but also in the body axis direction of the subject H. Therefore, the data volume of the view data can be reduced efficiently.

[0056] In the above embodiment, the operator specifies the field of view, detects the area surrounding the subject, and specifies the region of interest using a scanogram image, but this is not limited to this. A camera that captures an optical image of the subject H may be installed in the CT device 2 or the examination room in which the CT device 2 is installed, and the operator may use the optical image captured by the camera to specify the field of view, detect the area surrounding the subject, and specify the region of interest. The optical image is an example of a preliminary image in the present disclosure.

[0057] In the above embodiment, the photon counting detector outputs detection signals in four energy bands, but this is not limiting and the detector may output raw data in multiple energy bands, such as less than four or more than four.

[0058] In addition, in the above embodiment, the processor includes a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array) whose circuit configuration can be changed after manufacture, and a dedicated electrical circuit that is a processor having a circuit configuration designed specifically to execute specific processing such as an ASIC.

[0059] The various processes described above may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., a combination of multiple FPGAs, a combination of a CPU and an FPGA, etc.). Multiple processing units may also be configured by a single processor. An example of configuring multiple processing units by a single processor is a form in which a processor is used that realizes the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip, such as an SoC (System on a Chip).

[0060] The following are supplementary clauses of the present disclosure. (Supplementary clause 1) A data processing device including a processor, wherein the processor acquires raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being acquired by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements, deriving integral data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest, and deriving view data to be stored based on the raw data within the region of interest and the integrated data outside the region of interest. (Supplementary clause 2) The data processing device according to Supplementary clause 1, wherein the processor stores the view data. (Supplementary clause 3) The data processing device according to Supplementary clause 1 or 2, wherein the processor identifies the region of interest based on a field of view set when performing the imaging. (Supplementary clause 4) The data processing device according to Supplementary clause 1 or 2, wherein the processor identifies the region of interest based on a region surrounding the subject included in a preliminary image acquired when performing the imaging. (Supplementary Item 5) The data processing device according to Supplementary Item 1 or 2, wherein the processor identifies the region of interest based on an input of the region of interest by a user. (Supplementary Item 6) A data processing method comprising: a computer acquiring raw data corresponding to the number of photons of the radiation in each of a plurality of energy bands of the radiation, the raw data being acquired by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements; deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.(Supplementary Item 7) A data processing program that causes a computer to execute the steps of: acquiring raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being acquired by performing imaging in which radiation that has been emitted from a radiation source and passed through a subject is detected by a detector including a plurality of photon-counting detection elements; deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

[0061] REFERENCE SIGNS LIST 1 Medical imaging system 2 CT apparatus 3 Console 4 Gantry 4A Opening 4B Rotating plate 5 Radiation source 6 Radiation tube 7 Bow tie filter 8 Bed 9 Detector 9P Detecting element 10 Data processing device 11 CPU 12 Data processing program 13 Storage 14 Display 15 Input device 16 Memory 17 I / F 18 Bus 21 Information acquisition unit 22 Imaging control unit 23 Region of interest identification unit 24 Integration unit 25 Derivation unit 26 Storage control unit 27 Reconstruction unit 30 Display screen 31 First scanogram image 32 Second scanogram image 33, 34 Initial effective field of view 35, 36 Effective field of view 37, 38 Region 40 Region of interest 41 Region of non-interest 51 to 53, 54 to 56 Region of interest H Subject I0 Integrated data R0 Raw data V0 View data

Claims

1. A data processing device comprising: a processor that acquires raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being obtained by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting detection elements; derives integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and derives view data to be stored based on the raw data within the region of interest and the integrated data outside the region of interest.

2. The data processing device according to claim 1, wherein said processor stores said view data.

3. A data processing device according to claim 1 or 2, wherein the processor identifies the region of interest based on a field of view set when the imaging is performed.

4. A data processing device according to claim 1 or 2, wherein the processor identifies the region of interest based on a region surrounding the subject contained in a pre-image acquired when the imaging is performed.

5. The data processing device according to claim 1 or 2, wherein the processor identifies the region of interest based on a user's input of the region of interest.

6. A data processing method in which a computer acquires raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting type detection elements, deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest, and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

7. A data processing program that causes a computer to execute the steps of: acquiring raw data corresponding to the number of photons of radiation in each of a plurality of energy bands of the radiation, the raw data being obtained by performing imaging in which radiation emitted from a radiation source and transmitted through a subject is detected by a detector including a plurality of photon-counting type detection elements; deriving integrated data by integrating the raw data in each of the plurality of energy bands outside a predetermined region of interest; and deriving view data to be saved based on the raw data within the region of interest and the integrated data outside the region of interest.

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