Medical system and storing medium

Abstract

To notify a user that an X-ray generating device may be deteriorating due to aging before the image quality of a CT image deteriorates.SOLUTION: A medical system may include: an X-ray generating device; a detector for detecting X-rays radiated by the X-ray generating device; and one or more processors which, every time a prescribed calibration scan is executed, calculate a characteristic value of the X-rays irradiated with from the X-ray generating device based on data on the X-rays detected by the detector, and determine whether to output an alert based on change in the characteristic value over time.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a medical system for emitting X-rays and a storage medium on which instructions for controlling the medical system are recorded. [Background technology]

[0002] CT systems are known as medical systems for non-invasively imaging a subject. CT systems are widely used in hospitals and other medical facilities because they can acquire cross-sectional images of a subject in a short scanning time.

[0003] A CT system applies a predetermined voltage to the cathode-anode tube of an X-ray tube to generate X-rays. The generated X-rays pass through the subject and are detected by a detector. The CT system reconstructs a CT image of the subject based on the data detected by the detector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6031618 Summary of the Invention [Problem to be solved by the invention]

[0005] SECT (Single Energy CT) is known as an imaging technique for CT systems. SECT is a method of generating X-rays by applying a predetermined voltage (e.g., 120 kV) to the cathode-anode tube of an X-ray tube, thereby obtaining a CT image of the subject. However, with SECT, different substances can have similar CT values, making it difficult to identify the different substances.

[0006] Therefore, research and development has been conducted on DECT (Dual Energy CT) technology. DECT is a technology that can distinguish materials by using X-rays in different energy ranges, and can obtain images that are useful for diagnosis in clinical settings, so it is beginning to be widely used. DECT technology is known for its kV switching technology, which switches the tube voltage of the X-ray tube between low and high tube voltages.

[0007] On the other hand, the material discrimination accuracy of DECT's kV switching method decreases with aging of the X-ray generator (e.g., X-ray tube, generator, etc.). Therefore, to prevent a decrease in material discrimination accuracy, it is important for CT system users to know about the aging deterioration of the X-ray generator as soon as possible. However, there is no method for detecting the deterioration of the X-ray generator, and CT system users become aware of the deterioration when the deterioration appears as noise or artifacts in the CT image. Therefore, there is a need for a technology that can notify users of the possibility of aging deterioration in the X-ray generator before the image quality of the CT image deteriorates (before noise or artifacts appear in the CT image). [Means for solving the problem]

[0008] A first aspect of the present invention is an X-ray generating apparatus, a detector for detecting X-rays irradiated from the X-ray generator; one or more processors, calculating a characteristic value of the X-rays irradiated from the X-ray generator based on the data of the X-rays detected by the detector each time a predetermined calibration scan is performed; Determining whether to output an alert based on the change in the characteristic value over time. and one or more processors executing A medical system including:

[0009] A second aspect of the present invention is a method for detecting an X-ray beam from an X-ray generating device, a detector for detecting X-rays irradiated from the X-ray generator; one or more processors 1. A non-transitory computer-readable storage medium included in or in communication with a medical system including: The instructions stored on the storage medium, when executed by the one or more processors, cause the one or more processors to: calculating a characteristic value of the X-rays irradiated from the X-ray generator based on the data of the X-rays detected by the detector each time a predetermined calibration scan is performed; Determining whether to output an alert based on the change in the characteristic value over time. A non-transitory computer-readable storage medium that causes the computer to execute the method. [Effects of the Invention]

[0010] In the present invention, a characteristic value of the X-rays irradiated from the X-ray generator is calculated based on data including information on the X-rays detected by the detector, and a determination is made as to whether to output an alert based on a change in the characteristic value over time. Therefore, by outputting an alert when there is a large change in the characteristic value over time, it is possible to notify the user that there are signs of deterioration in the X-ray generator before the image quality of the CT image deteriorates. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram of a CT system 10 according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing a flow executed on each medical treatment day. [Figure 3] FIG. 10 is an explanatory diagram of calibration. [Figure 4] FIG. 10 is an explanatory diagram of calibration data acquired on treatment day 1. [Figure 5] FIG. 11 is an enlarged view of absorption coefficient data g11. [Figure 6] FIG. 11 is an enlarged view of absorption coefficient data h11. [Figure 7] FIG. 10 shows absorption coefficient data g21 of the first reference substance obtained on medical examination day 2. [Figure 8] FIG. 10 is a diagram showing absorption coefficient data h21 of the second reference substance obtained on treatment day 2. [Figure 9] FIG. 10 is a diagram showing an example of the flow of step ST20. [Figure 10] FIG. 10 is an explanatory diagram of the flow of FIG. [Figure 11] FIG. 10 is an explanatory diagram when steps ST201 and ST202 are executed for channel 2. [Figure 12] FIG. 10 is an explanatory diagram when steps ST201 and ST202 are executed for channel j. [Figure 13] FIG. 10 is an explanatory diagram when steps ST201 and ST202 are executed for channel n. [Figure 14] FIG. 10 is an explanatory diagram when step ST20 is performed on the absorption coefficient data of the second reference substance. [Figure 15] FIG. 10 is a diagram showing absorption coefficient data g11 to g31 of the first reference substance obtained on medical examination days 1 to 3. [Figure 16] FIG. 10 is a diagram showing absorption coefficient data h11 to h31 of the second reference substance obtained on medical examination days 1 to 3. [Figure 17] FIG. 10 is an explanatory diagram of step ST20. [Figure 18] FIG. 10 is an explanatory diagram when steps ST201 to ST204 are executed on the absorption coefficient data of the second reference substance. [Figure 19] FIG. 10 is a diagram showing absorption coefficient data gi1 of the first reference substance obtained on examination day i. [Figure 20] FIG. 10 is a diagram showing absorption coefficient data hi1 of the second reference substance obtained on medical examination day i. [Figure 21] FIG. 10 is an explanatory diagram of step ST20. [Figure 22] This is an explanatory diagram of the flow after the CT system is restarted. [Figure 23] FIG. 10 is a diagram showing absorption coefficient data gp1 of the first reference substance obtained on treatment day p. [Figure 24] FIG. 10 is a diagram showing absorption coefficient data hp1 of the second reference substance obtained on treatment day p. [Figure 25] FIG. 10 is a diagram showing absorption coefficient data gq1 of the first reference substance obtained on medical examination day q. [Figure 26] FIG. 10 is a diagram showing absorption coefficient data hq1 of the second reference material obtained on medical examination day q. [Figure 27] FIG. 10 is an explanatory diagram of step ST20. [Figure 28] FIG. 10 is an explanatory diagram when steps ST201 to ST204 are executed on the absorption coefficient data of the second reference substance. [Figure 29] FIG. 10 is a diagram showing an example of the flow of step ST20 when a multi-row detector is used. [Figure 30] FIG. 10 is an explanatory diagram of the flow of step ST20 when updating the reference absorption coefficient for each medical examination day. [Figure 31] FIG. 10 is a diagram showing absorption coefficient data g11 to gi1 of the first reference substance acquired on medical examination days 1 to i. [Figure 32] FIG. 10 is an explanatory diagram of a flow performed in the second embodiment. [Figure 33] FIG. 1 is an explanatory diagram of an X-ray spectrum. [Figure 34] 10 is a diagram showing an X-ray spectrum SL2 corresponding to low kV generated on clinical day 2, and an X-ray spectrum SH2 corresponding to high kV generated on clinical day 2. FIG. [Figure 35] FIG. 10 is a diagram showing an example of the flow of step ST60. [Figure 36] FIG. 36 is an explanatory diagram of the flow of FIG. 35. [Figure 37] FIG. 10 is an explanatory diagram of steps ST604 to ST606. [Figure 38] 1 is a diagram showing a schematic diagram of an X-ray spectrum SLi corresponding to low kV generated on a clinical day i and an X-ray spectrum SHi corresponding to high kV generated on a clinical day i. FIG. [Figure 39] FIG. 10 is an explanatory diagram of step ST60. [Figure 40]This is an explanatory diagram of the flow after the CT system is restarted. [Figure 41] FIG. 10 is an explanatory diagram of the flow of step ST60 when calculating the standard energy value for each medical treatment date. [Figure 42] FIG. 10 is a diagram showing X-ray spectra SL1 to SLi corresponding to low kV acquired on clinical days 1 to i. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a description will be given of an embodiment of the invention, but the present invention is not limited to the following embodiment.

[0013] (First embodiment) FIG. 1 is a block diagram of a CT system 10 according to the first embodiment. The CT system 10 includes a gantry 102 and a table 116 .

[0014] The gantry 102 has a bore 107 into which a subject 112 is transferred and scanned.

[0015] The gantry 102 is equipped with an X-ray generator 104, a filter unit 103, a pre-collimator 105, a detector 108, and the like.

[0016] The X-ray generating device 104 includes an X-ray tube 104A and a generator 104B. The generator 104B supplies power to the X-ray tube 104A. The X-ray tube 104A outputs X-rays when a predetermined voltage is applied to the cathode-anode tube. The X-ray tube 104 is configured to be rotatable on a path centered on a rotation axis 206 within the XY plane. Here, the Z direction represents the body axis direction, the Y direction represents the vertical direction (the height direction of the table 116), and the X direction represents the direction perpendicular to the Z direction and the Y direction. In this embodiment, the X-ray tube 104A is an X-ray tube compatible with a kV switching system, in which the tube voltage applied to the X-ray tube can be alternately switched between a first tube voltage and a second tube voltage. Note that although the CT system 10 includes one X-ray tube 104A in this embodiment, it may also include two X-ray tubes 104A.

[0017] The filter section 103 includes, for example, a flat plate filter and / or a bowtie filter. The pre-collimator 105 is a member for narrowing down the irradiation range of X-rays so that unnecessary areas are not irradiated with X-rays.

[0018] The detector 108 includes a plurality of detector elements 202. The plurality of detector elements 202 detects X-rays 106 emitted from the X-ray tube 104A and passing through an object 112, such as a patient. Thus, the X-ray detector 108 can acquire projection data for each view.

[0019] Projection data detected by the detector 108 is collected by the DAS 214. The DAS 214 performs predetermined processing on the collected projection data, including sampling and digital conversion. The processed projection data is sent to the computer 216. The computer 216 stores the data from the DAS 214 in the storage device 218. The storage device 218 includes one or more storage media for recording programs, instructions to be executed by a processor, and the like. The storage medium may be, for example, one or more non-transitory computer-readable storage media. The storage device 218 may include, for example, a hard disk drive, a floppy disk drive, a compact disk read / write (CD-R / W) drive, a digital versatile disk (DVD) drive, a flash drive, and / or a solid-state recording drive.

[0020] Computer 216 includes one or more processors 217. Using the one or more processors, computer 216 outputs commands and parameters to DAS 214, X-ray controller 210, and / or gantry motor controller 212 to control system operations such as data acquisition and / or processing. Computer 216 also uses the one or more processors to perform various processes such as signal processing, data processing, and image processing in each step of the flow described below. Although FIG. 1 shows one or more processors 217 included in computer 216, one or more processors 217 may be distributed between computer 216 and other components (e.g., X-ray controller 210, gantry motor controller 212, table controller 118, etc.).

[0021] An operator console 220 is coupled to the computer 216. An operator can operate the operator console 220 to enter predetermined operator inputs related to the operation of the CT system 10 into the computer 216. The computer 216 receives operator inputs, including commands and / or scan parameters, via the operator console 220 and controls system operation based on the operator inputs. The operator console 220 can include a keyboard (not shown) or a touch screen for the operator to enter commands and / or scan parameters.

[0022] The X-ray controller 210 controls the X-ray generator 104 based on instructions from the computer 216. Also, the gantry motor controller 212 controls the gantry motor based on instructions from the computer 216 so that components such as the X-ray tube 104A and the detector 108 rotate.

[0023] Although FIG. 1 shows only one operator console 220 , more than one operator console may be coupled to computer 216 .

[0024] The CT system 10 may also be coupled to multiple remotely located displays, printers, workstations, and / or similar devices, for example, via wired and / or wireless networks.

[0025] In one embodiment, for example, CT system 10 may include or be coupled to a picture archiving and communication system (PACS) 224. In an exemplary implementation, PACS 224 may be coupled to a remote system, such as a radiology department information system, a hospital information system, and / or an internal or external network (not shown).

[0026] The computer 216 supplies instructions to the table motor controller 118 for controlling the table 116. Based on the received instructions, the table motor controller 118 can control the table motor so as to move the table 116. For example, the table motor controller 118 can move the table 116 so that the subject 112 is positioned appropriately for imaging.

[0027] As described above, DAS 214 samples and digitally converts projection data acquired by detector elements 202. Image reconstructor 230 then reconstructs an image using the sampled and digitally converted data. Image reconstructor 230 includes one or more processors that may perform the image reconstruction processing. While image reconstructor 230 is shown in FIG. 1 as a separate component from computer 216, image reconstructor 230 may form part of computer 216. Computer 216 may also perform one or more functions of image reconstructor 230. Furthermore, image reconstructor 230 may be located remotely from CT system 10 and operatively connected to CT system 10 using a wired or wireless network.

[0028] Image reconstructor 230 can store the reconstructed image in storage device 218. Image reconstructor 230 may also transmit the reconstructed image to computer 216. Computer 216 can transmit the reconstructed image and / or patient information to a display device 232 communicatively coupled to computer 216 and / or image reconstructor 230.

[0029] The various methods and processes described herein may be recorded as executable instructions on a non-transitory computer-readable storage medium included in or in communication with the CT system 10. The executable instructions may be recorded on a single storage medium or may be distributed across multiple storage media. One or more processors included in the CT system 10 perform the various methods, steps, and processes described herein in accordance with the instructions recorded on the storage medium.

[0030] The CT system 10 is configured as described above. The CT system of this embodiment is compatible with the kV switching method of DECT (Dual Energy CT) and can perform material discrimination. However, the accuracy of material discrimination using the DECT kV switching method decreases with aging of the X-ray generator. Therefore, in order to prevent a decrease in the accuracy of material discrimination, it is important for users of the CT system to be aware of the aging deterioration of the X-ray generator as soon as possible. However, currently, there is no method for detecting the deterioration of X-ray generators. Therefore, users of the CT system become aware of the deterioration of the X-ray generator by visually recognizing the deterioration in the image quality of the CT image. Therefore, there is a demand for a technology that can notify users that the X-ray generator may be deteriorating with age before the image quality of the CT image deteriorates.

[0031] Therefore, the inventors have conducted extensive research and devised a method for informing a user of the possibility of aging deterioration in the X-ray generator before the user of the CT system visually recognizes the deterioration in the image quality of the CT image. This method is described below.

[0032] Before describing this embodiment in detail, the features of this embodiment can be summarized as follows. In this embodiment, a calibration scan is periodically performed. The processor calculates a characteristic value of the X-rays irradiated from the X-ray generator 104 based on the X-ray data detected by the detector 108 as a result of the calibration scan. The processor then determines whether to output an alert based on changes in the characteristic value over time. Therefore, by outputting an alert when there is a large change in the characteristic value over time, it is possible to notify the user that there are signs of deterioration in the X-ray generator before the image quality of the CT image deteriorates.

[0033] Additionally, calibration scans are recommended to be performed periodically (for example, every morning) to obtain stable CT images. Therefore, if calibration scans are performed periodically as before, an alert will be output to notify the user as needed. This means that users can be notified of signs of deterioration in the X-ray generator before the image quality of CT images deteriorates, without having to perform additional scans in addition to the calibration scan.

[0034] The following describes a method for determining whether to output an alert based on changes over time in the characteristic values ​​of X-rays in the CT system of this embodiment. Note that in the following, two characteristic values ​​of X-rays, namely, the absorption coefficient of a first reference material and the absorption coefficient of a second reference material, are considered.

[0035] 2 is a diagram showing a flow executed on each medical treatment day. Hereinafter, for convenience of explanation, this method will be described using an example in which a calibration scan is executed once on a medical treatment day, but the frequency at which the calibration scan is executed is not limited to once a day. For example, the calibration scan may be executed multiple times a day (e.g., in the morning and afternoon), or days on which the calibration scan is not executed may be periodically set.

[0036] First, a description will be given of clinic day 1. On clinic day 1, flow 100 is executed. Flow 100 will be described below.

[0037] In step ST11, a calibration scan is performed using kV switching, in which the tube voltage applied to the X-ray tube 104A is alternately switched between a first tube voltage (low kV) and a second tube voltage (high kV).

[0038] FIG. 3 is an explanatory diagram of the calibration. In calibration using the kV switching method, for example, z combinations P1 to Pz of values ​​of three parameters (rotation speed, cone angle, and tube current) are prepared. The z combinations P1 to Pz are preset and stored in the CT system, and calibration scans S1 to Sz are executed for each combination. By executing the calibration scan, X-rays are detected by the detector 108. The processor generates calibration data based on the X-ray data detected by the detector 108. FIG. 2 shows an example in which z pieces of calibration data D1 to Dz are generated for z presets P1 to Pz. Each piece of calibration data includes various coefficients, such as an absorption coefficient and a correction coefficient for beam hardening. However, here, only calibration data representing the absorption coefficient relevant to the description of this embodiment will be considered as the calibration data.

[0039] When analyzing the absorption coefficient, it is not necessary to analyze the absorption coefficients of all calibration data D1 to Dz, but it is sufficient to analyze the change over time in the absorption coefficient of calibration data obtained in a specific calibration scan among the calibration scans S1 to Sz. Therefore, in the following, the absorption coefficient will be explained focusing only on the calibration data D1 obtained in the calibration scan S1.

[0040] The absorption coefficients include the absorption coefficient of the first reference material and the absorption coefficient of the second reference material. Therefore, by performing a calibration scan, the absorption coefficients of the first reference material and the second reference material are calculated. The two reference materials can be, for example, a combination of water and iodine or a combination of water and calcium. Figure 4 is an explanatory diagram of the calibration data acquired on clinic day 1.

[0041] FIG. 4 shows the absorption coefficient data g representing the absorption coefficient of the first reference substance of the calibration data acquired on clinical day 1. 11 ~g 1m and absorption coefficient data h representing the absorption coefficient of the second reference material. 11 ~h 1m An outline of the

[0042] Absorption coefficient data g 11 represents the absorption coefficient of the first reference material in each channel of the first column of the detector, and the absorption coefficient data g 12 ~g 1m respectively represent the absorption coefficients of the first reference material in each channel of the second to m-th columns of the detector. Also, the absorption coefficient data h 11 represents the absorption coefficient of the second reference material in each channel of the first row of the detector, and the absorption coefficient data h 12 ~h 1m and m respectively represent the absorption coefficients of the second reference material in each channel of the second to m-th columns of the detector. For example, if m=64, that is, if the detector has a multi-row structure of 64 columns, then for the first reference material, 64 absorption coefficient data g 11 ~g 1,64 is generated, and for the second reference material, 64 absorption coefficient data h 11 ~h 1,64 In the following, in order to simplify the explanation of the absorption coefficient data, we will consider the case where m=1, that is, the detector has a single-row structure. Therefore, for the first reference material, the absorption coefficient data g 11 For the second reference material, only the absorption coefficient data h 11 I will only consider this.

[0043] Figure 5 shows the absorption coefficient data g 11 6 shows the absorption coefficient data h 11 FIG. It should be noted that the waveforms of the absorption coefficient data shown below are shown for the purpose of explaining the embodiment, and may differ from the actual waveforms.

[0044] In FIG. 5, among the absorption coefficients of the first reference material in channels 1 to n of the detector, only the absorption coefficients of channels 1, 2, j, and n are shown. In channel 1, the absorption coefficient is "a 11 " and for channel 2, the absorption coefficient is "a 12 ” and for channel j, the absorption coefficient is “a 1j ” and for channel n, the absorption coefficient is “a 1n " is indicated.

[0045] In FIG. 6, among the absorption coefficients of the second reference material in channels 1 to n of the detector, only the absorption coefficients of channels 1, 2, j, and n are shown. In channel 1, the absorption coefficient is "b 11 ” and for channel 2, the absorption coefficient is “b 12 ” and for channel j, the absorption coefficient is “b 1j ” and for channel n, the absorption coefficient is “b 1n " is indicated.

[0046] In this embodiment, the absorption coefficient a of the first reference substance calculated on treatment day 1 is 11 ~a 1n is saved as the first reference absorption coefficient, which is the basis for determining whether to output an alert. Also, the absorption coefficient b of the second reference substance calculated on clinical day 1 is saved as the first reference absorption coefficient, which is the basis for determining whether to output an alert. 11 ~b 1n is saved as a second reference absorption coefficient that serves as a criterion for determining whether to output an alert.

[0047] After step ST11 is executed, the process proceeds to step ST12, where the subject is examined according to the examination schedule for the first day of treatment.

[0048] Next, a description will be given of clinic day 2. On clinic day 2, flow 200 is executed. First, in step ST11, a calibration scan is performed, and the processor generates calibration data (such as absorption coefficient data) based on the data obtained in the calibration scan.

[0049] FIG. 7 shows the absorption coefficient data g of the first reference material obtained on clinic day 2. 21 8 shows the absorption coefficient data h of the second reference material obtained on clinical day 2. 21 FIG.

[0050] In addition, Figure 7 shows the absorption coefficient data g obtained on treatment day 2. 21 In addition to the absorption coefficient data g obtained on treatment day 1 11 Also shown in Figure 8 is the absorption coefficient data h obtained on treatment day 2. 21 In addition to the absorption coefficient data h obtained on treatment day 1, 11 is also shown. After executing step ST11, the process proceeds to step ST20.

[0051] In step ST20, it is determined whether to output an alert based on the change in the absorption coefficient over time. 9 is a diagram showing an example of the flow of step ST20, and FIG. 10 is an explanatory diagram of the flow of FIG. 9. In FIG. 10, the absorption coefficient data g of the first reference substance shown in FIG. 11 and g 21 is shown.

[0052] In step ST201, the processor calculates the difference between the reference absorption coefficient (absorption coefficient on treatment day 1) and the absorption coefficient on treatment day 2. Specifically, the processor calculates the difference between the reference absorption coefficient a 11 and absorption coefficient a on treatment day 2 21 The difference Δa21 Calculate the difference in absorption coefficients Δa 21 Once calculated, the process proceeds to step ST202.

[0053] In step ST202, the processor 21 is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. 21 exceeds the threshold TH1 (Δa 21 >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0054] On the other hand, the difference in absorption coefficient Δa 21 does not exceed the threshold TH1 (Δa 21 ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0055] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0056] FIG. 11 is an explanatory diagram when steps ST201 and ST202 are executed for channel 2. In step ST201, the processor calculates the absorption coefficient a 12 and absorption coefficient a on treatment day 2 22 The difference Δa 22 Calculate the difference in absorption coefficients Δa 22 Once calculated, the process proceeds to step ST202.

[0057] In step ST202, the processor 22 is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. 22 exceeds the threshold TH1 (Δa 22 >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0058] On the other hand, the difference in absorption coefficient Δa 22 does not exceed the threshold TH1 (Δa 22 ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0059] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channels 1 and 2, but have not yet been executed for the other channels 3 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 2 to channel 3. Then, the processor returns to step ST201.

[0060] Similarly, every time the channel is incremented in step ST204, the processor returns to step ST201 and repeatedly executes the loop of steps ST201 to ST204 (see FIG. 12).

[0061] FIG. 12 is an explanatory diagram when steps ST201 and ST202 are executed for channel j. In step ST201, the processor calculates the absorption coefficient a 1j and absorption coefficient a on treatment day 2 2j The difference Δa 2j Calculate the difference in absorption coefficients Δa 2j Once calculated, the process proceeds to step ST202.

[0062] In step ST202, the processor 2j is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. 2j exceeds the threshold TH1 (Δa 2j >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0063] On the other hand, the difference in absorption coefficient Δa 2j does not exceed the threshold TH1 (Δa 2j ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0064] Similarly, every time the channel is incremented in step ST204, the processor returns to step ST201 and repeatedly executes the loop of steps ST201 to ST204 (see FIG. 13).

[0065] FIG. 13 is an explanatory diagram when steps ST201 and ST202 are executed for channel n. In step ST201, the processor calculates the absorption coefficient a 1n and absorption coefficient a on treatment day 2 2n The difference Δa 2n Calculate the difference in absorption coefficients Δa 2n Once calculated, the process proceeds to step ST202.

[0066] In step ST202, the processor 2n is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. 2n exceeds the threshold TH1 (Δa 2n>TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0067] On the other hand, the difference in absorption coefficient Δa 2n does not exceed the threshold TH1 (Δa 2n ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0068] In step ST203, the processor determines whether steps ST201 to ST204 have been executed for all channels. In this case, steps ST201 to ST204 have been executed for all channels 1 to n. Therefore, the processor proceeds to step ST205.

[0069] In step ST205, the processor determines whether the analysis of the absorption coefficients of both the first and second reference materials is complete. Here, the absorption coefficient of the first reference material has been analyzed, but the absorption coefficient of the second reference material has not. Therefore, the process returns to step ST201.

[0070] Returning to step ST201, the processor calculates the absorption coefficient data h of the second reference material as described for the first reference material. 11 and h 21 (see FIG. 8), the processing of steps ST201 to ST204 is executed.

[0071] 14 is an explanatory diagram for performing step ST20 on the absorption coefficient data of the second reference substance. In FIG. 14, the absorption coefficient data h 11 and h 21 is shown.

[0072] In step ST201, the processor calculates the reference absorption coefficient b 11 and absorption coefficient b on treatment day 2 21 The difference Δb21 Calculate the difference in absorption coefficients Δb 21 Once calculated, the process proceeds to step ST202.

[0073] In step ST202, the processor calculates Δb 21 is compared with the threshold value TH2, and based on the comparison result, it is determined whether to output an alert. 21 exceeds the threshold TH2 (Δb 21 >TH2), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0074] On the other hand, the difference in absorption coefficient Δb 21 does not exceed the threshold TH2 (Δb 21 ≦TH2), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0075] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0076] Similarly, a loop of steps ST201 to ST204 is executed. 11 and h 21 While the processing of steps ST201 to ST204 is being performed on channels 1 to n, if the difference in absorption coefficient for a certain channel exceeds the threshold value TH2, it is determined that an alert should be output.

[0077] Meanwhile, the processor calculates the absorption coefficient data h of the second reference material. 11 and h12 Steps ST201 to ST204 have been executed for all channels, and if the difference in absorption coefficient for any channel is equal to or less than the threshold value TH2, the process proceeds to step ST205.

[0078] In step ST205, the processor determines whether the analysis of the absorption coefficients of both the first and second reference materials has been completed. Here, the analysis of the absorption coefficients of both the first and second reference materials has been completed. Therefore, the processor determines that output of an alert is unnecessary and ends step ST20. In this case, the process proceeds to step ST22, where the subject is examined according to the examination schedule for clinic day 2.

[0079] In this embodiment, it is assumed that no alert was output on consultation day 2. Therefore, after step ST20 is completed, the test on the subject is performed. Returning to Figure 2, we continue the explanation.

[0080] Next, a description will be given of clinic day 3. On clinic day 3, flow 200 is executed in the same manner as on clinic day 2. First, in step ST11, a calibration scan is performed, and the processor generates calibration data (such as absorption coefficient data) based on the data obtained in the calibration scan.

[0081] FIG. 15 shows the absorption coefficient data g of the first reference material obtained on clinical days 1 to 3. 11 ~g 31 16 shows the absorption coefficient data h of the second reference material obtained on clinical days 1 to 3. 11 ~h 31 is shown.

[0082] After executing step ST11, the process proceeds to step ST20. In step ST20, it is determined whether to output an alert based on the change in the absorption coefficient over time.

[0083] FIG. 17 is an explanatory diagram of step ST20. In step ST201, the processor calculates the reference absorption coefficient a 11 and absorption coefficient a on treatment day 2 31 The difference Δa 31 Calculate the difference in absorption coefficients Δa 31 Once calculated, the process proceeds to step ST202.

[0084] In step ST202, the processor 31 is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. 31 exceeds the threshold TH1 (Δa 31 >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0085] On the other hand, the difference in absorption coefficient Δa 31 does not exceed the threshold TH1 (Δa 31 ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0086] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0087] Similarly, a loop of steps ST201 to ST204 is executed. 11 and g 31While the processing of steps ST201 to ST204 is being performed for channels 1 to n, if the difference in absorption coefficient for a certain channel exceeds the threshold value TH1, it is determined that an alert should be output.

[0088] On the other hand, the processor calculates the absorption coefficient data g of the first reference substance. 11 and g 31 If steps ST201 to ST204 have been executed for all channels and the difference in absorption coefficient for any channel is equal to or less than threshold value TH1, the process proceeds to step ST205. In step ST205, the processor determines whether or not analysis of the absorption coefficients of both the first and second reference substances has been completed. Here, analysis of the absorption coefficient of the first reference substance has been completed, but analysis of the absorption coefficient of the second reference substance has not yet been completed. Therefore, the process returns to step ST201.

[0089] Returning to step ST201, the processor executes the processes of steps ST201 to ST204 for the absorption coefficient of the second reference substance.

[0090] FIG. 18 is an explanatory diagram when steps ST201 to ST204 are executed on the absorption coefficient data of the second reference substance.

[0091] In step ST201, the processor calculates the absorption coefficient b 11 and absorption coefficient b on treatment day 2 21 The difference Δb 21 Calculate the difference in absorption coefficients Δb 31 Once calculated, the process proceeds to step ST202.

[0092] In step ST202, the processor calculates Δb 31 is compared with the threshold value TH2, and based on the comparison result, it is determined whether to output an alert. 31 exceeds the threshold TH2 (Δb 31>TH2), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0093] On the other hand, the difference in absorption coefficient Δb 31 does not exceed the threshold TH2 (Δb 31 ≦TH2), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0094] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0095] Similarly, a loop of steps ST201 to ST204 is executed. 11 and h 31 While the processing of steps ST201 to ST204 is being performed for channels 1 to n, if the difference in absorption coefficient for a certain channel exceeds the threshold value TH2, it is determined that an alert should be output.

[0096] Meanwhile, the processor calculates the absorption coefficient data h of the second reference material. 11 and h 13 Steps ST201 to ST204 have been executed for all channels, and if the difference in absorption coefficient for any channel is equal to or less than the threshold value TH2, the process proceeds to step ST205.

[0097] In step ST205, the processor determines whether the analysis of the absorption coefficients of both the first and second reference substances has been completed. Here, the analysis of the absorption coefficients of both the first and second reference substances has been completed. Therefore, the processor determines that output of an alert is unnecessary and ends step ST20. In this case, the process proceeds to step ST22, where the subject is examined according to the examination schedule for clinical day 3.

[0098] In this embodiment, it is assumed that no alert was output on consultation day 3. Therefore, after step ST20 is completed, the test on the subject is performed.

[0099] Next, the treatment day i will be described. On the treatment day i, flow 200 is executed in the same manner as on the treatment day 2. In step ST11, a calibration scan is performed. The processor generates calibration data (such as absorption coefficient data) based on the data obtained in the calibration scan. FIG. 19 shows the absorption coefficient data g of the first reference material obtained on the examination date i. i1 20 shows the absorption coefficient data h of the second reference material obtained on the day i of the examination. i1 is shown.

[0100] After executing step ST11, the process proceeds to step ST20.

[0101] In step ST20, it is determined whether to output an alert based on the change in the absorption coefficient over time.

[0102] FIG. 21 is an explanatory diagram of step ST20. FIG. 21 shows the absorption coefficient data g obtained on treatment days 1 to i. 11 ~g i1 is shown.

[0103] In step ST201, the processor calculates the absorption coefficient a 11 and the absorption coefficient a on treatment day i i1The difference Δa i1 Calculate the difference in absorption coefficients Δa i1 Once calculated, the process proceeds to step ST202.

[0104] In step ST202, the processor i1 is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. i1 exceeds the threshold TH1 (Δa i1 >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0105] On the other hand, the difference in absorption coefficient Δa i1 does not exceed the threshold TH1 (Δa i1 ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0106] Here, the difference in absorption coefficients calculated in channel 1, Δa i1 But Δa i1 >TH1 is satisfied. Therefore, an alert is output.

[0107] When an alert is output, the user can, for example, request a service to perform inspection 11 (see FIG. 2). Furthermore, when an alert is output, the CT system may send data representing the time change of the absorption coefficient to a back office, and the data representing the time change of the absorption coefficient may be analyzed in the back office.

[0108] If the service inspection 11 determines that the X-ray generator has a fault or is broken, the X-ray generator is repaired or replaced. After the X-ray generator is repaired or replaced, an operation check is performed on the CT system, and if it is confirmed to be operating normally, the CT system is restarted. Figure 22 is an explanatory diagram of the flow after the CT system is restarted. Here, it is assumed that inspections etc. are completed on consultation day i and the CT system is able to resume operation on the next consultation day p.

[0109] The following explains the treatment date p. On clinic day p, the same flow 100 as on clinic day 1 is executed. Therefore, in step ST11, a calibration scan is executed. The processor generates calibration data (such as absorption coefficient data) based on the data obtained by the calibration scan.

[0110] FIG. 23 shows the absorption coefficient data g of the first reference substance obtained on the day p of the examination. p1 24 is a graph showing the absorption coefficient data h of the second reference material obtained on the day p of the examination. p1 FIG.

[0111] Absorption coefficient data g p1 represents the absorption coefficient of the first reference material in each channel of the first row of the detector. Also, the absorption coefficient data h p1 represents the absorption coefficient of the second reference material in each channel of the first column of the detector. In Figures 23 and 24, of the absorption coefficients of the first reference material in channels 1 to n of the detector, only the absorption coefficients of channels 1, 2, j, and n are shown as representatives.

[0112] On clinical days 1 to i, the absorption coefficient a of the first reference substance obtained on clinical day 1 11 ~a 1n is the absorption coefficient of the first reference material obtained on clinical day 2 to clinical day i (e.g., absorption coefficient a 21 , a 31 , a i1 However, the X-ray generator was inspected on clinic day i, and the CT system resumed operation on the following clinic day p. Therefore, the absorption coefficient a on clinic day 1, which was obtained before the X-ray generator inspection, 11 ~a 1ncannot be used as a reference value for determining the amount of change over time in the absorption coefficient of the first reference substance. Therefore, the processor p1 ~a pn is stored as a new first reference value for determining the amount of change over time in the absorption coefficient of the first reference substance.

[0113] Similarly, the processor calculates the absorption coefficient b obtained on the treatment day p. p1 ~b pn is stored as a new second reference value for determining the amount of change over time in the absorption coefficient of the second reference substance.

[0114] After step ST11 is executed, the process proceeds to step ST12, where an examination of the subject is carried out.

[0115] Next, the treatment date q will be explained. On the consultation day q, flow 200 is executed in the same manner as on the consultation day 2. Accordingly, in step ST11, a calibration scan is executed. The processor generates calibration data (such as absorption coefficient data) based on the data obtained by the calibration scan. FIG. 25 shows the absorption coefficient data g of the first reference material obtained on the consultation day q. q1 26 shows the absorption coefficient data h of the second reference material obtained on the day q of the examination. q1 is shown.

[0116] After executing step ST11, the process proceeds to step ST20. In step ST20, it is determined whether to output an alert based on the change in the absorption coefficient over time.

[0117] FIG. 27 is an explanatory diagram of step ST20. In step ST201, the processor calculates the absorption coefficient a of channel 1 on treatment day p. p1 and the absorption coefficient a on treatment day q q1 The difference Δa q1 Calculate the difference in absorption coefficients Δa q1Once calculated, the process proceeds to step ST202.

[0118] In step ST202, the processor q1 is compared with a threshold TH1, and based on the comparison result, it is determined whether to output an alert. q1 exceeds the threshold TH1 (Δa q1 >TH1), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0119] On the other hand, the difference in absorption coefficient Δa q1 does not exceed the threshold TH1 (Δa q1 ≦TH1), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0120] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0121] Similarly, a loop of steps ST201 to ST204 is executed. p1 and g q1 While the processing of steps ST201 to ST204 is being performed for channels 1 to n, if the difference in absorption coefficient for a certain channel exceeds the threshold value TH1, it is determined that an alert should be output.

[0122] On the other hand, the processor calculates the absorption coefficient data g of the first reference substance. 11 and g 31If steps ST201 to ST204 have been executed for all channels and the difference in absorption coefficient for any channel is equal to or less than threshold value TH1, the process proceeds to step ST205. In step ST205, the processor determines whether or not analysis of the absorption coefficients of both the first and second reference substances has been completed. Here, the absorption coefficient of the first reference substance has been analyzed, but the absorption coefficient of the second reference substance has not been analyzed. Therefore, the process returns to step ST201.

[0123] Returning to step ST201, the processor executes the processes of steps ST201 to ST204 for the absorption coefficient of the second reference substance.

[0124] FIG. 28 is an explanatory diagram when steps ST201 to ST204 are executed on the absorption coefficient data of the second reference substance.

[0125] In step ST201, the processor calculates the absorption coefficient b p1 and the absorption coefficient b on treatment day q q1 The difference Δb q1 Calculate the difference in absorption coefficient Δb q1 Once calculated, the process proceeds to step ST202.

[0126] In step ST202, the processor calculates Δb q1 is compared with the threshold value TH2, and based on the comparison result, it is determined whether to output an alert. q1 exceeds the threshold TH2 (Δb q1 >TH2), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0127] On the other hand, the difference in absorption coefficient Δb q1 does not exceed the threshold TH2 (Δb q1 ≦TH2), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0128] In step ST203, the processor determines whether steps ST201 and ST202 have been executed for all channels. Here, steps ST201 and ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the process returns to step ST201.

[0129] Similarly, a loop of steps ST201 to ST204 is executed. 11 and h q1 While the processing of steps ST201 to ST204 is being performed for channels 1 to n, if the difference in absorption coefficient for a certain channel exceeds the threshold value TH2, it is determined that an alert should be output.

[0130] Meanwhile, the processor calculates the absorption coefficient data h of the second reference material. 11 and h 13 Steps ST201 to ST204 have been executed for all channels, and if the difference in absorption coefficient for any channel is equal to or less than the threshold value TH2, the process proceeds to step ST205.

[0131] In step ST205, the processor determines whether the analysis of the absorption coefficients of both the first and second reference materials has been completed. Here, the analysis of the absorption coefficients of both the first and second reference materials has been completed. Therefore, the processor determines that it is not necessary to output an alert, and ends step ST20. In this case, the process proceeds to step ST22, where the subject is examined according to the examination schedule for the examination day q.

[0132] In this embodiment, it is assumed that no alert was output on the consultation day q. Therefore, after step ST20 is completed, the examination of the subject is carried out.

[0133] Similarly, flow 200 is executed on and after the examination day q. If the difference in the absorption coefficient exceeds the threshold, an alert is output, the X-ray generator is inspected, and the X-ray tube is repaired or replaced as necessary. When the CT system is restarted, the absorption coefficient of the calibration data obtained on the first day of restart is determined as the new reference absorption coefficient. Therefore, after the CT system is restarted, the absorption coefficient obtained on the first day of restart is used as the reference value to analyze the change in the absorption coefficient over time.

[0134] As described above, according to this embodiment, absorption coefficient data is acquired each time a calibration scan is performed. Then, the difference between the absorption coefficients is calculated to determine the amount of change in the absorption coefficient over time, and it is determined whether the difference in the absorption coefficient is greater than a threshold value (TH1 or TH2). The threshold value TH1 or TH2 can be set to, for example, a value appropriate for determining whether aging degradation has occurred in the X-ray generator. Therefore, if aging degradation has occurred in the X-ray generator, an alert is output, allowing the user to know in advance that the X-ray generator may be experiencing a malfunction or failure before the deterioration of the X-ray generator appears as noise or artifacts in the CT image. Therefore, the user can take necessary measures, such as requesting a service inspection, before the deterioration of the X-ray generator appears as noise or artifacts in the CT image.

[0135] In the first embodiment, for the sake of convenience, a single-row detector is used to explain the method for determining whether to output an alert, but the present invention can also be applied to a multi-row detector.

[0136] FIG. 29 is a diagram showing an example of the flow of step ST20 when a multi-row detector is used. Step ST20 shown in FIG. 29 differs from step ST20 shown in FIG. 9 in that step ST2051 is provided between step ST205 and step ST22.

[0137] In step ST2051, the processor determines whether or not the processes of steps ST201 to ST205 have been completed for all columns of the detector. If there is a column for which the processes of steps ST201 to ST205 have not been completed, the process returns to step ST1. On the other hand, if the processes of steps ST201 to ST205 have been completed for all columns of the detector, the process proceeds to step ST22.

[0138] By providing this step ST2051, it is possible to cope with the case of a plurality of rows of detectors.

[0139] In this embodiment, steps ST201 to ST204 are executed in the order of channels 1 to n, but steps ST201 to ST204 do not necessarily have to be executed in the order of channels 1 to n, and steps ST201 to ST204 can be executed in any order of channels. Also, when a detector with multiple rows is used, steps ST201 to ST205 do not necessarily have to be executed in the order of rows 1 to m, and steps ST201 to ST205 can be executed in any order of columns. Also, steps ST201 and ST202 may be executed for one or more channels in one row of the detector, and then steps ST201 and ST202 may be executed for one or more channels in another row of the detector.

[0140] In this embodiment, when analyzing the absorption coefficient data of the first reference substance in step ST20, the absorption coefficient a 11 ~a 1n is used as the first reference absorption coefficient to determine whether to output an alert. In addition, in step ST20, when analyzing the absorption coefficient data of the second reference substance, the absorption coefficient b 11 ~b 1n is used as the second reference absorption coefficient to determine whether to output an alert. However, the reference absorption coefficient may be updated for each medical treatment day (see FIG. 30).

[0141] FIG. 30 is an explanatory diagram of the flow of step ST20 when the reference absorption coefficient is updated for each medical examination day. In Fig. 30, step ST20 includes step ST200 for calculating a reference absorption coefficient between step ST11 and step ST201. By providing step ST200, the reference absorption coefficient can be updated for each treatment day and step ST20 can be executed. The processing flow of step ST20 shown in Fig. 30 will be described below with reference to Fig. 31.

[0142] FIG. 31 shows the absorption coefficient data g of the first reference material acquired on clinical days 1 to i. 11 ~g i1 FIG.

[0143] In step ST11, the absorption coefficient data g of the first reference substance on the medical treatment date i is i1 Once acquired, proceed to step ST20.

[0144] In step ST20, it is determined whether to output an alert based on the change in the absorption coefficient over time. First, in step ST200, the processor calculates the absorption coefficient a of channel 1 on medical day 1 to medical day i-1. 11 ~a i-1,1 (the absorption coefficient obtained from the previously performed calibration scan) i1 Calculate the reference absorption coefficient r i1 is used as the first reference absorption coefficient in channel 1. The reference absorption coefficient r i1 is, for example, the absorption coefficient a 11 ~a i-1,1 The average value of the absorption coefficient a 11 ~a i-1,1 The reference absorption coefficient r may be a weighted average of i1 Once calculated, the process proceeds to step ST201.

[0145] In step ST201, the processor calculates a reference absorption coefficient r 11 and the absorption coefficient a on treatment day i i1 The difference Δdi1 Calculate the difference in absorption coefficient Δd i1 Once calculated, the process proceeds to step ST202.

[0146] In step ST202, the processor i1 is compared with the threshold value TH3, and based on the comparison result, it is determined whether to output an alert. i1 exceeds the threshold TH3 (Δd i1 >TH3), the processor determines that the change in the absorption coefficient over time is large and therefore determines to output an alert. In this case, the process proceeds to step ST21, where the processor causes the display unit to output an alert.

[0147] On the other hand, the difference in absorption coefficient Δd i1 does not exceed the threshold TH3 (Δd i1 ≦TH3), the change in the absorption coefficient over time is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST203.

[0148] In step ST203, the processor determines whether steps ST200 to ST202 have been executed for all channels. Here, steps ST200 to ST202 have been executed for channel 1, but have not yet been executed for the other channels 2 to n. Therefore, the processor proceeds to step ST204, where it increments the channel from channel 1 to channel 2. Once the channel has been incremented, the processor returns to step ST200.

[0149] Similarly, the loop of steps ST200 to ST204 is repeatedly executed, so that the reference absorption coefficient is calculated for each channel, and it is possible to determine whether or not to output an alert.

[0150] Although FIG. 31 illustrates the calculation of a first reference absorption coefficient used when analyzing the change over time in the absorption coefficient of a first reference substance, a similar method can also be used to calculate a second reference absorption coefficient used when analyzing the change over time in the absorption coefficient of a second reference substance.

[0151] In addition, in Figure 31, the absorption coefficient a 11 ~a i-1,1 Using all of the above, the reference absorption coefficient r i1 However, not all absorption coefficients a 11 ~a i-1,1 using the reference absorption coefficient r i1 There is no need to calculate the absorption coefficient a 11 ~a i-1,1 Use at least one of the absorption coefficients to calculate the reference absorption coefficient r i1 may be calculated.

[0152] In addition, in Figure 31, the reference absorption coefficient r i1 However, for other medical treatment days, the reference absorption coefficient can be calculated based on the past absorption coefficients, similar to the medical treatment day i.

[0153] (Second embodiment) In the first embodiment, an example of calculating an absorption coefficient as an example of a characteristic value of an X-ray has been described. In the second embodiment, an example of calculating a representative value of an X-ray spectrum will be described.

[0154] Before describing the second embodiment in detail, the features of the second embodiment can be summarized as follows. That is, in the second embodiment, a calibration scan is performed, and an X-ray spectrum corresponding to a high kV and an X-ray spectrum corresponding to a low kV are obtained based on data obtained by the calibration scan. Then, a processor calculates a representative value of the X-ray spectrum corresponding to a high kV and a representative value of the X-ray spectrum corresponding to a low kV. The representative value of the X-ray spectrum is, for example, an average energy value or an integrated energy value. The processor determines whether to output an alert based on a change over time in the representative value of the X-ray spectrum. Therefore, by outputting an alert when there is a large change over time in the representative value of the X-ray spectrum, the user can be notified that there are signs of deterioration in the X-ray generator before the image quality of the CT image deteriorates.

[0155] FIG. 32 is an explanatory diagram of the flow carried out in the second embodiment. First, a description will be given of clinic day 1. On clinic day 1, flow 300 is executed.

[0156] In step ST51, a calibration scan is performed using kV switching, in which the tube voltage applied to the X-ray tube 104A is alternately switched between a first tube voltage (low kV) and a second tube voltage (high kV). After performing the calibration scan, the processor generates an X-ray spectrum based on the data obtained in the calibration scan (see FIG. 33).

[0157] FIG. 33 is an explanatory diagram of an X-ray spectrum. The X-ray spectrum SL1 is an X-ray spectrum corresponding to low kV, and the X-ray spectrum SH1 is an X-ray spectrum corresponding to high kV. After generating the X-ray spectra SL1 and SH1, the process proceeds to step ST52.

[0158] In step ST52, the processor calculates a representative value of the X-ray spectrum SL1. In the second embodiment, the processor calculates the average energy value RL1 of the X-ray spectrum SL1 as the representative value of the X-ray spectrum SL1. The processor also calculates a representative value of the X-ray spectrum SH1. In the second embodiment, the processor calculates the average energy value RH1 of the X-ray spectrum SH1 as the representative value of the X-ray spectrum SH1. However, the representative value of the X-ray spectrum SL1 is not limited to the average energy value RL1, and any value representing a characteristic of the X-ray spectrum SL1, such as an energy integral value, can be used as the representative value of the X-ray spectrum SL1. Similarly, the representative value of the X-ray spectrum SH1 is not limited to the average energy value RH1, and any value representing a characteristic of the X-ray spectrum SH1, such as an energy integral value, can be used as the representative value of the X-ray spectrum SH1.

[0159] The average energy value RL1 calculated on treatment day 1 is saved as a first energy reference value that serves as a criterion for determining whether to output an alert, and the average energy value RH1 calculated on treatment day 1 is saved as a second energy reference value that serves as a criterion for determining whether to output an alert.

[0160] After step ST52 is executed, the process proceeds to step ST53, where an examination of the subject is carried out.

[0161] Next, a description will be given of clinic day 2. On clinic day 2, flow 400 is executed. In step ST51, a calibration scan is performed. After performing the calibration scan, the processor generates an X-ray spectrum based on data obtained from the calibration scan. Figure 34 schematically shows an X-ray spectrum SL2 corresponding to low kV generated on clinic day 2 and an X-ray spectrum SH2 corresponding to high kV generated on clinic day 2.

[0162] After executing step ST51, the process proceeds to step ST60.

[0163] In step ST60, it is determined whether to output an alert based on the change over time in the average energy value of the X-ray spectrum.

[0164] FIG. 35 is a diagram showing an example of the flow of step ST60, and FIG. 36 is an explanatory diagram of the flow of FIG. In step ST601, the processor calculates the average energy value RL2 of the X-ray spectrum SL2 on the examination day 2. After calculating the average energy value RL2, the process proceeds to step ST602.

[0165] In step ST602, the processor calculates an energy difference ΔDL1 between the reference energy value RL1 and the average energy value RL2. After calculating the energy difference ΔDL1, the processor proceeds to step ST603.

[0166] In step ST603, the energy difference ΔDL1 is compared with a threshold value TH5, and based on the comparison result, it is determined whether to output an alert. For example, if the energy difference ΔDL1 exceeds the threshold value TH5 (ΔDL1>TH5), the processor determines that the energy difference ΔDL1 is large and therefore determines to output an alert. In this case, the process proceeds to step ST61, and the processor causes the display unit to output an alert.

[0167] On the other hand, if the energy difference ΔDL1 does not exceed the threshold value TH5 (ΔDL1≦TH5), the energy difference ΔDL1 is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST604 (see FIG. 37).

[0168] FIG. 37 is an explanatory diagram of steps ST604 to ST606. In step ST604, the processor calculates the average energy value RH2 of the X-ray spectrum SH2 on the examination day 2. After calculating the average energy value RH2, the process proceeds to step ST605.

[0169] In step ST605, the processor calculates the energy difference ΔDH1 between the reference energy value RH1 and the average energy value RH2. After calculating the energy difference ΔDH1, the processor proceeds to step ST606.

[0170] In step ST606, the energy difference ΔDH1 is compared with a threshold value TH6, and based on the comparison result, it is determined whether to output an alert. For example, if the energy difference ΔDH1 exceeds the threshold value TH6 (ΔDH1>TH6), the processor determines that the energy difference ΔDH1 is large and therefore determines that an alert should be output. In this case, the process proceeds to step ST61, and the processor causes the display unit to output an alert.

[0171] On the other hand, if the energy difference ΔDH1 does not exceed the threshold value TH6 (ΔDH1≦TH6), the energy difference ΔDL1 is small, and therefore it is determined that an alert should not be output. In this case, although both the change over time of the low kV average energy value and the change over time of the high kV average energy value were analyzed, it was determined that an alert should not be output, so the process proceeds to step ST62, and the subject is examined according to the examination schedule for examination day 2.

[0172] Similarly, flow 400 is executed on medical days 3 to i in the same manner as on medical day 2. Therefore, on medical days 3 to i, a determination is made as to whether to output an alert based on the change over time in the average energy value of the X-ray spectrum, using the same procedure as on medical day 2.

[0173] Next, the treatment date i will be described. In step ST51, a calibration scan is performed. After performing the calibration scan, the processor generates an X-ray spectrum based on data obtained from the calibration scan. Figure 38 schematically shows an X-ray spectrum SLi corresponding to low kV generated on clinical day i and an X-ray spectrum SHi corresponding to high kV generated on clinical day i.

[0174] After executing step ST51, the process proceeds to step ST60. In step ST60, the processor determines whether to output an alert based on the change over time in the average energy value of the X-ray spectrum.

[0175] FIG. 39 is an explanatory diagram of step ST60. In step ST601, the processor calculates the average energy value RLi of the X-ray spectrum SLi on the examination date i. After calculating the average energy value RLi, the process proceeds to step ST602.

[0176] In step ST602, the processor calculates the energy difference ΔDLi between the reference energy value RLi and the average energy value RLi. After calculating the energy difference ΔDLi, the processor proceeds to step ST603.

[0177] In step ST603, the energy difference ΔDLi is compared with a threshold TH5, and based on the comparison result, it is determined whether to output an alert. For example, if the energy difference ΔDLi exceeds the threshold TH5 (ΔDLi>TH5), the processor determines that the energy difference ΔDLi is large and therefore determines to output an alert.

[0178] Here, it is assumed that the energy difference ΔDLi satisfies ΔDLi>TH5, and therefore an alert is output.

[0179] When an alert is output, the user can, for example, request a service to perform an inspection 11 (see FIG. 2). If the service's inspection 11 determines that the X-ray generator has a fault or is broken, the X-ray generator is repaired or replaced. After the X-ray generator is repaired or replaced, an operation check is performed on the CT system, and if it is confirmed to be operating normally, the CT system is restarted. FIG. 40 is an explanatory diagram of the flow after the CT system has been restarted. Here, it is assumed that inspections etc. are completed on consultation day i and the CT system is able to resume operation on the next consultation day p.

[0180] On treatment day p, the same flow 300 as on treatment day 1 is executed, and the average energy value of the X-ray spectrum is calculated. Then, from treatment day q onwards, the same flow 400 as on treatment day 2 is executed. Therefore, the energy difference is calculated based on the average energy value calculated on treatment day p, and if the energy difference exceeds the threshold, an alert is output. Therefore, from treatment day q onwards, it is possible to determine whether to output an alert based on the change over time in the average energy value of the X-ray spectrum.

[0181] As described above, according to the second embodiment, an X-ray spectrum is generated each time a calibration scan is performed. Then, the energy difference is calculated to determine the amount of change over time in the average energy value, and it is determined whether the energy difference is greater than a threshold value. Therefore, if the energy difference is large, an alert is output, so the user can know in advance that there is a possibility of a fault or malfunction in the X-ray generator before the image quality of the CT image deteriorates. This allows the user to take necessary measures, such as requesting a service to inspect the X-ray generator.

[0182] In the second embodiment, the average energy value of the X-ray spectrum calculated on treatment day 1 is determined as the energy reference value, and it is determined whether to output an alert. However, the energy reference value may be calculated for each treatment day based on the average energy value of X-ray spectra acquired in the past (see FIG. 41).

[0183] FIG. 41 is an explanatory diagram of the flow of step ST60 when calculating the standard energy value for each medical treatment date.

[0184] In Figure 41, step ST60 includes step ST6011, between step ST601 and step ST602, for calculating a reference energy value of a low-kV X-ray spectrum. Furthermore, step ST60 includes step ST6041, between step ST604 and step ST605, for calculating a reference energy value of a high-kV X-ray spectrum. By providing step ST6011 and step ST6041, it is possible to calculate a reference energy value for each examination day and execute step ST60. The processing flow of step ST60 shown in Figure 41 will be described below with reference to Figure 42.

[0185] Figure 42 shows the X-ray spectra SL1 to SL2 corresponding to low kV acquired on clinical days 1 to i. i FIG.

[0186] In step ST51, the X-ray spectrum SL corresponding to the low kV on the treatment date i is i Once acquired, the process proceeds to step ST601.

[0187] In step ST601, the processor calculates the average energy value RLi of the X-ray spectrum SLi on the examination date i. After calculating the average energy value RLi, the process proceeds to step ST6011.

[0188] In step ST6011, the processor calculates the average energy values ​​RL1 to RL2 for the treatment days 1 to i-1. i-1 Based on the first energy reference value v i Calculate this energy reference value v i is used as a reference value to determine whether to output an alert on treatment day i. The energy reference value v i For example, the average energy values ​​RL1 to RL i-1 The average value of the energy values ​​RL1 to RL i-1 The energy reference value v may be a weighted average of i Once calculated, the process proceeds to step ST602.

[0189] In step ST602, the processor calculates the energy difference ΔRLi between the energy reference value vi and the average energy value RLi. After calculating the energy difference ΔRLi, the processor proceeds to step ST603.

[0190] In step ST603, the energy difference ΔRLi is compared with a threshold value TH5, and based on the comparison result, it is determined whether to output an alert. For example, if the energy difference ΔRLi exceeds the threshold value TH5 (ΔRLi>TH5), the processor determines that the energy difference ΔRLi is large and therefore determines to output an alert. In this case, the process proceeds to step ST61, and the processor causes the display unit to output an alert.

[0191] On the other hand, if the energy difference ΔRLi does not exceed the threshold value TH5 (ΔRLi≦TH5), the energy difference ΔRLi is small, so the processor determines not to output an alert. In this case, the process proceeds to step ST604. Therefore, it is possible to determine whether to output an alert.

[0192] Note that while Figure 42 illustrates the calculation of a first energy reference value used when analyzing the change over time in the average energy value of an X-ray spectrum corresponding to a low kV, a similar method can also be used to calculate a second energy reference value used when analyzing the change over time in the average energy value of an X-ray spectrum corresponding to a high kV.

[0193] In addition, in FIG. 42, the average energy values ​​RL1 to RL2 for the treatment days 1 to i-1 are i-1 However, the average energy values ​​RL1 to RL2 for the treatment days 1 to i-1 are calculated using all of the above. i-1 may be used to calculate the energy reference value vi.

[0194] Note that Figure 42 shows a method for calculating the energy reference value vi on treatment day i, but for other treatment days, the energy reference values ​​can also be calculated based on the average energy values ​​obtained from past X-ray spectra, just like treatment day i.

[0195] In this embodiment, an example is shown in which a CT system is used as the medical system. However, the present invention is not limited to the CT system, and can be applied to systems other than the CT system (for example, a PET-CT system) as long as the medical system irradiates an X-ray source onto the subject 112. [Explanation of symbols]

[0196] 10 CT systems 100 Flow 102 Gantry 103 Filter section 104 X-ray generator 104A X-ray tube 104B Generator 106 X-ray 107 Bore 108 detectors 116 tables 118 Table Motor Controller 200 Flow 202 detector element 210 X-ray controller 212 Gantry motor controller 214 DAS 216 Computer 218 Storage device 220 Operator Console 224 PACS 230 Image Reconstructor 232 Display device 300 Flow 400 Flow

Claims

1. an X-ray generator; a detector for detecting X-rays emitted from the X-ray generator; one or more processors, calculating a characteristic value of the X-rays irradiated from the X-ray generator based on the data of the X-rays detected by the detector each time a predetermined calibration scan is performed; Determining whether to output an alert based on the change in the characteristic value over time. one or more processors executing medical systems, including

2. the medical system periodically executes the predetermined calibration scan while alternately switching a tube voltage between a first tube voltage and a second tube voltage; The medical system of claim 1 , wherein the characteristic values ​​include an absorption coefficient of a first reference substance and an absorption coefficient of a second reference substance.

3. The medical system of claim 2 , wherein the one or more processors calculate an absorption coefficient of a first reference material and an absorption coefficient of a second reference material each time the predetermined calibration scan is performed.

4. the one or more processors Calculating a first reference absorption coefficient that is used as a reference for determining whether to output an alert; calculating a first difference between the first reference absorption coefficient and the absorption coefficient of the first reference substance; and comparing the first difference with a first threshold and determining whether to output an alert based on the comparison result; The medical system according to claim 3 , wherein the medical system executes the following:

5. the one or more processors calculating a second reference absorption coefficient that is used as a reference for determining whether to output an alert; calculating a second difference between the second reference absorption coefficient and the absorption coefficient of the second reference substance; and comparing the second difference with a second threshold and determining whether to output an alert based on the comparison result; The medical system according to claim 4 , wherein the medical system executes the following:

6. each time the one or more processors perform the predetermined calibration scan, calculating the first reference absorption coefficient based on the absorption coefficient of a first reference material obtained from a previously performed predetermined calibration scan; or calculating the second reference absorption coefficient based on the absorption coefficient of the second reference material obtained by the previously performed predetermined calibration scan; The medical system according to claim 5 , wherein the medical system executes the following:

7. the first reference material is water and the second reference material is iodine; or The medical system of claim 6 , wherein the first reference material is water and the second reference material is calcium.

8. The medical system according to claim 2 , wherein when the alert is output, the medical system sends data representing a change in absorption coefficient over time to a back office.

9. The medical system of claim 2 , wherein the absorption coefficient of the first reference material and the absorption coefficient of the second reference material are calculated for each channel of each row of the detector.

10. the medical system periodically executes the predetermined calibration scan while alternately switching a tube voltage between a first tube voltage and a second tube voltage; 2. The medical system according to claim 1, wherein the characteristic values ​​include a first representative value of a first X-ray spectrum corresponding to the first tube voltage and a second representative value of a second X-ray spectrum corresponding to the second tube voltage.

11. The one or more processors perform the following steps each time the predetermined calibration scan is performed: The medical system of claim 10 , further comprising: calculating a first representative value of the first X-ray spectrum and a second representative value of the second X-ray spectrum.

12. the one or more processors calculating a first energy reference value that is used as a criterion for determining whether to output an alert; calculating a first difference between the first energy reference value and the first representative value; and comparing the first difference with a first threshold value and determining whether to output an alert based on the comparison result; The medical system of claim 10 , wherein the medical system executes the following:

13. the one or more processors calculating a second energy reference value that is used as a criterion for determining whether to output an alert; calculating a second difference between the second energy reference value and the second representative value; and comparing the second difference with a second threshold and determining whether to output an alert based on the comparison result; The medical system of claim 12 , wherein the medical system executes the following:

14. each time the one or more processors perform the predetermined calibration scan, calculating the first difference based on a first representative value of a first X-ray spectrum obtained by a previously performed predetermined calibration scan; or calculating the second difference based on a second representative value of a second X-ray spectrum obtained by the previously performed predetermined calibration scan; The medical system of claim 13 , wherein the medical system executes the following:

15. the first representative value is an average energy value or an integral energy value of the first X-ray spectrum, The medical system according to claim 10 , wherein the second representative value is an average energy value or an integral energy value of the second X-ray spectrum.

16. the medical system performs a plurality of calibration scans; The medical system of claim 1 , wherein one calibration scan of the plurality of calibration scans is executed as the predetermined calibration scan.

17. an X-ray generator; a detector for detecting X-rays emitted from the X-ray generator; one or more processors; 1. A non-transitory computer-readable storage medium included in or in communication with a medical system including: The instructions stored on the storage medium, when executed by the one or more processors, cause the one or more processors to: calculating a characteristic value of the X-rays irradiated from the X-ray generator based on the data of the X-rays detected by the detector each time a predetermined calibration scan is performed; Determining whether to output an alert based on the change in the characteristic value over time. A non-transitory computer-readable storage medium that causes the

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