CT apparatus

Abstract

To provide a CT apparatus in which an optimal imaging condition can be selected regardless of the user's experience, and workability is improved.SOLUTION: A CT apparatus includes: a memory unit that, when imaging an image of an inspection item A to which a radioactive ray is applied, stores multiple imaging durations required during imaging and predetermined imaging conditions according to each imaging duration; a display unit 5 that displays the multiple imaging durations; an input unit that accepts a user's choice of the imaging duration displayed on the display unit 5; and an imaging condition determination unit that determines the imaging conditions corresponding to the imaging duration accepted by the input unit as imaging conditions at the time of imaging.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a CT device. [Background technology]

[0002] Industrial CT devices are widely used to inspect small electronic components such as lithium-ion batteries at high resolution. In this CT device, a radiation source that irradiates radiation, such as an X-ray beam, and a detector that detects the X-ray beam from the radiation source with two-dimensional resolution are arranged facing each other. A rotatable inspection table is provided between the radiation source and the detector. While the X-ray beam is irradiating the object placed on the inspection table, the inspection table rotates once, irradiating the object with the X-ray beam in all directions.

[0003] To perform imaging using a CT scanner, various imaging conditions must be set. These include tube current, tube voltage, material and thickness of metal filter, exposure time, number of views, binning, number of images accumulated, radiation dose, and many other setting items. To obtain optimal images, these various imaging conditions must be set appropriately. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6519663 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as mentioned above, since there are many setting items, it is difficult for an inexperienced user to set appropriate conditions, and even for an experienced user, it is a time-consuming task. Therefore, a technology has been developed in which icons with preset parameters of shooting conditions are arranged in a matrix on a display screen according to a two-dimensional index related to image quality, and the shooting conditions are determined by the user selecting from the displayed icons (Patent Document 1).

[0006] In the case of Patent Document 1, the difficulty of setting the shooting conditions is certainly alleviated to a certain extent, but it is still difficult for inexperienced users to select an appropriate icon, as selection is not possible without knowledge of CT imaging, such as density resolution and resolution, and it remains a time-consuming task even for experienced users, as they must select an icon after taking into account density resolution and resolution, etc.

[0007] An embodiment of the present invention has been made to solve the above-mentioned problems, and its purpose is to provide a CT device that allows a user to select optimal shooting conditions regardless of their experience, thereby improving operability. [Means for solving the problem]

[0008] A CT apparatus in an embodiment of the present invention, when irradiating a test object with radiation to capture an image of the test object, comprises: a memory unit that stores a plurality of imaging times required for imaging and imaging conditions that are set in advance according to each imaging time; a display unit that displays the plurality of imaging times; an input unit that accepts from a user a selection of the imaging times displayed on the display unit; and an imaging condition determination unit that determines the imaging condition corresponding to the imaging time accepted by the input unit as the imaging condition for imaging, and the imaging conditions are set so that the radiation dose value detected by a detector is the same or within a certain range for any of the imaging times. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view diagrammatically illustrating a CT apparatus according to a first embodiment. [Diagram 2] FIG. 13 is a schematic diagram showing a state in which the display unit displays a shooting time. [Diagram 3] FIG. 2 is a block diagram showing a configuration of a control unit. [Figure 4] 11 is a table showing an example of shooting conditions according to shooting time. [Diagram 5]13 is a table showing an example of shooting conditions according to shooting times in Modification Example 1. [Figure 6] 13 is a table showing an example of shooting conditions according to shooting times in Modification Example 2. [Figure 7] 11 is a schematic diagram showing a method of calculating a dose when a metal filter portion is used. FIG. [Figure 8] 13 is a table showing an example of shooting conditions according to shooting time in Modification 3. [Figure 9] 10A and 10B are diagrams showing the display state of shooting conditions on the display unit, where (a) shows the standard mode and (b) shows the expert mode. [Figure 10] 13 is a table showing an example of shooting conditions according to shooting time in the second embodiment. [Figure 11] FIG. 13 is a block diagram showing the configuration of a control unit in a third embodiment. [Figure 12] 5A to 5C are diagrams showing examples of shooting conditions in each preset table. [Figure 13] FIG. 23 is a diagram showing an example of shooting conditions for each preset table in the sixth modified example. [Figure 14] FIG. 13 is a diagram showing an example of switching of imaging modes in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (First embodiment) Hereinafter, the CT device according to the first embodiment will be described in detail with reference to the drawings. Fig. 1 is a side view showing the CT device according to the first embodiment.

[0011] The CT device 100 is a device used for non-destructive testing of an object to be inspected A. The CT device 100 irradiates the periphery of the object to be inspected A with a radiation beam that passes through the object to be inspected A, and detects the amount of radiation attenuated by passing through the object to be inspected A. Then, based on the detection result, the CT device 100 generates a CT image, which is a cross-sectional image of the object to be inspected A. The CT device 100 also generates a 3D image from the multiple CT images generated.

[0012] As shown in Fig. 1, the CT device 100 includes an inspection table 1, a radiation source 2, a detector 3, a metal filter unit 4, a display unit 5, an input unit 6, and a control unit 7. The inspection table 1 is a table having a mounting surface on which an object A to be inspected is placed. The inspection table 1 is movable in a direction parallel to the mounting surface or in a direction perpendicular to the mounting surface. The inspection table 1 is also rotatable around an axis perpendicular to the mounting surface. The inspection table 1 includes an XY mechanism, a rotating table 12, and a lifting mechanism 13.

[0013] The XY mechanism 11 places the object to be inspected A on it. For example, a ball screw mechanism driven by a servo motor can be used as the XY mechanism 11. The XY mechanism 11 is movable in a direction parallel to the optical axis of the radiation beam, a direction parallel to the placement surface, and a direction perpendicular to the optical axis of the radiation beam.

[0014] The rotating table 12 is provided under the XY mechanism. The rotating table 12 is configured, for example, by an actuator including a drive source such as a motor, and is provided rotatable about an axis perpendicular to the mounting surface. During irradiation with the radiation beam, the rotating table 12 rotates, whereby the radiation beam is irradiated in all directions on the object A to be inspected.

[0015] The lifting mechanism 13 is provided below the rotary table 12. A ball screw mechanism driven by a servo motor can be used as the lifting mechanism 13. The lifting mechanism 13 is movable in a direction perpendicular to the mounting surface. That is, the height of the object A to be inspected can be adjusted by moving the lifting mechanism 13 in a direction perpendicular to the mounting surface.

[0016] The radiation source 2 irradiates, for example, a radiation beam that penetrates the inspection object A. The radiation beam is a bundle of radiation that spreads in a cone shape with a fan angle and a cone angle, with the focus of the radiation source as its apex. In this embodiment, the radiation source 2 is, for example, a reflection type or transmission type microfocus X-ray tube or nanofocus X-ray tube, and the radiation beam is an X-ray beam. Note that the radiation beam is not limited to an X-ray beam, and any beam that penetrates the inspection object A, such as gamma rays, can be used.

[0017] The detector 3 is provided facing the radiation source 2 across the inspection table 1 and the object to be inspected A. The detector 3 is provided so that the center of the imaging area coincides with the optical axis of the radiation source 2. The detector 3 detects a two-dimensional distribution of radiation intensity attenuated according to the transmission path of the radiation beam, and outputs a fluoroscopic image. The detector 3 is formed, for example, of a flat panel detector (FPD). The detector 3 has a moving mechanism for adjusting the distance to the object to be inspected A. The detector 3 can be moved by the moving mechanism in a direction perpendicular to the imaging area (parallel to the optical axis of the radiation source 2). The detector 3 can also be moved by the moving mechanism in a direction parallel to the imaging area in order to align the optical axis of the radiation source with the center of the imaging area.

[0018] The metal filter unit 4 is disposed in a position close to the radiation source 2 and between the object A to be inspected and the radiation source 2. The metal filter unit 4 is a thin plate member having a thickness of about several mm. The metal filter unit 4 is a metal plate made of copper, aluminum, iron, or an alloy containing these. A plurality of metal filter units 4 are provided, and each metal filter unit 4 is made of a different material and has a different thickness.

[0019] The metal filter part 4 is provided so as to be movable by a moving mechanism (not shown). For example, a ball screw mechanism driven by a servo motor can be used as the moving mechanism. The moving mechanism moves the metal filter part 4, which is made of a material and has a thickness corresponding to the imaging time selected by the user, onto the optical axis of the radiation source 2. A radiation beam is irradiated onto the metal filter part 4 arranged on the optical axis, and the radiation beam that has passed through the metal filter part 4 is irradiated onto the object A to be inspected. By transmitting the radiation through the metal filter part 4, the occurrence of metal artifacts is suppressed.

[0020] The display unit 5 is, for example, a monitor such as a liquid crystal display or an organic EL display. The display unit 5 displays various images such as a fluoroscopic image, a CT image, and a 3D image of the object A, an imaging area, imaging conditions, etc. The display unit 5 may also display imaging conditions determined to be optimal by the control unit 7.

[0021] The display unit 5 displays a plurality of shooting times in which each shooting condition described later is set in advance. The shooting time is the time required for actual shooting. FIG. 2 is a schematic diagram showing a state in which the display unit 5 displays the shooting time. As shown in FIG. 2, the display unit 5 displays icons of shooting times. The display unit 5 displays four shooting times, for example, 1 min, 4 min, 7 min, and 25 min. The display unit 5 displays the icons of shooting times arranged in order from the shortest shooting time to the longest shooting time. Note that the shooting times in FIG. 2 are examples, and shooting times such as 10 min and 15 min may be set, or the number of shooting times may be four or more. In addition, the display of "beautiful" shown in FIG. 2 indicates that the longer the shooting time, the more beautiful and clear the image can be obtained.

[0022] The input unit 6 may use a keyboard, a mouse, a touch panel, or the like. The input unit 6 receives the imaging time displayed on the display unit 5 from the user. The input unit 6 may also receive various operations such as menu selection for actual imaging or test imaging, setting of imaging conditions, manual operation of the moving mechanism, start of imaging, and selection of a portion of the inspection object A to be observed.

[0023] The control unit 7 is configured with a computer and a driver circuit. The computer is configured with a storage such as an HDD or SSD, a RAM, a CPU, etc. The control unit 7 is connected to the input unit 6, and a user causes the control unit 7 to control each component of the CT device 100 via the input unit 6.

[0024] 3 is a block diagram showing the configuration of the control unit 7. As shown in FIG. 3, the control unit 7 has an examination table control unit 71, a radiation source control unit 72, a storage unit 73, and an imaging condition determination unit 74.

[0025] The inspection table control unit 71 controls the XY mechanism 11, the rotating table 12, and the lifting mechanism 13. Under the control of the inspection table control unit 71, the object A placed on the inspection table 1 can be aligned with the optical axis of the radiation beam, and the object A can be rotated once during irradiation with the radiation beam. In addition, the distance (FCD) between the radiation source 2 and the object A can be adjusted under the control of the inspection table control unit 71.

[0026] The radiation source control unit 72 controls the radiation source 2 to irradiate the object to be inspected A with a radiation beam. That is, under the control of the inspection table control unit 71 and the radiation source control unit 72, the object to be inspected A is irradiated with a radiation beam in all directions, and the detector 3 acquires a fluoroscopic image.

[0027] The storage unit 73 stores a plurality of preset imaging times. The storage unit 73 also stores optimal imaging conditions corresponding to each imaging time. FIG. 4 is a table showing an example of imaging conditions corresponding to the imaging time. As shown in FIG. 4, imaging conditions such as tube voltage, tube current, material and thickness of the metal filter unit 4, binning, exposure time, number of views, accumulation, and dose are set in association with each imaging time. That is, in the example of FIG. 4, the storage unit 73 stores the following when the imaging time is 1 minute: tube voltage is 200 kV, tube current is 100 mA, the metal filter unit 4 is made of copper and has a thickness of 1 mm, binning is 1, 100 ms, the number of views is 600, the number of accumulated sheets is 1, and the dose is 10,000.

[0028] Here, the dose refers to the amount of radiation signals detected by the detector 3. The dose at each imaging time is preset to be the same or within a certain range. In the example of Fig. 4, the doses at each imaging time of 1 minute, 4 minutes, 7 minutes, and 25 minutes are all the same at 10,000.

[0029] The dose is calculated according to the following formula (1). Dose = tube current x binning 2 × exposure time × number of frames (1) Moreover, the object to be inspected A may not be placed on the inspection table 1 and the actual measured value may be used.

[0030] In this embodiment, the dose is the same, but the dose at each imaging time may be set to be within a certain range. The certain range is determined by the specifications of the CT device 100 and the positional relationship of the object to be examined. For example, a limit value in the specifications of the CT device 100 is set, and a range within ±10% of the limit value is set as the certain range.

[0031] The photographing condition determination unit 74 determines the photographing conditions. That is, the photographing conditions corresponding to the photographing time selected by the user are determined as the photographing conditions for actual photographing. When the photographing condition determination unit 74 determines the photographing conditions, photographing starts.

[0032] As described above, the storage unit 73 of the CT device 100 of this embodiment stores a plurality of imaging times to which optimal imaging conditions are previously associated. Then, the user only needs to select the imaging time displayed on the display unit 5. This eliminates the need to set detailed imaging conditions. Therefore, even an inexperienced user can perform optimal imaging. Also, even an experienced user can omit time-consuming tasks, improving workability.

[0033] In addition, in this embodiment, the dose is the same for each imaging time. By making the dose the same, the SN ratio of the image becomes constant. By making the SN ratio of each imaging condition constant, an increase in the imaging time contributes only to the resolution of the image, and the optimum imaging condition for acquiring a beautiful image can be set by simply selecting that a longer imaging time means improved resolution.

[0034] (Variation 1) Next, a CT device 100 according to Modification 1 will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. In the first embodiment, the binning is the same at each imaging time, but in Modification 1, the binning is changed depending on the imaging time.

[0035] Fig. 5 is a table showing an example of shooting conditions according to shooting times in Modification 1. Fig. 5 shows examples of shooting times of 1 min, 2 min, 12 min, and 16 min. As shown in Fig. 5, the binning for shooting times of 1 min and 2 min is 2, but the binning for shooting times of 12 min and 16 min is 1.

[0036] If the binning is changed, the dose will be different based on the above formula (1). Therefore, in this modified example 1, the exposure time is further adjusted to set the dose to be the same. The exposure time is the time taken to capture one frame and is also called the integration time. As shown in FIG. 5, the exposure time for the 1 min and 2 min shooting times is 100 ms, while the exposure time for the 12 min and 16 min shooting times is 200 ms.

[0037] As described above, the CT device 100 of the first modification changes the binning at least in part of each imaging time, and adjusts the exposure time so that the dose at each imaging time is constant. As shown in the above formula (1), the binning is squared in the calculation of the dose. Therefore, when the dose is the same, if the binning value is increased, the exposure time and the number of accumulated frames become smaller. The imaging time is determined by "exposure time x number of views x number of accumulated frames". Therefore, if the binning value is increased, the imaging time can be shortened. Since the binning is linked to the resolution of the detector, it is possible to set the optimal imaging conditions for acquiring a clear image at each imaging time by changing the binning.

[0038] In addition, in the first modified example, the exposure time is adjusted so that the dose at each imaging time is the same even if the binning is changed. This allows the imaging time and dose to be adjusted without changing the quality of the X-rays, such as the penetration ability or spectrum. Therefore, the contrast at each imaging time is constant.

[0039] (Variation 2) Next, a CT device 100 according to a modified example 2 will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. In the modified example 1, the exposure time is adjusted so that the dose at each imaging time is the same even if the binning is changed, but in the modified example 2, the adjustment is made by the metal filter unit 4.

[0040] Fig. 6 is a table showing an example of imaging conditions according to imaging time in Modification 2. Fig. 6 shows examples of imaging times of 1 min, 2 min, and 3 min. In Modification 2, the material of the metal filter part 4 is the same, copper, but the thickness differs depending on each imaging time. As shown in Fig. 6, when the imaging time is 1 min, the thickness is 2 mm, when it is 2 min, the thickness is 1 mm, and when it is 3 min, the thickness is 0.2 mm. Note that the binning is 3 for 1 min, 2 for 2 min, and 1 for 3 min.

[0041] Even when the binning is different, the material and thickness of the metal filter part 4 are adjusted so that the dose at each imaging time is the same or within a certain range. The dose may be calculated using an actual measurement value or may be calculated, for example, by the following formulas (2) and (3).

[0042] 7 is a schematic diagram showing a method of calculating the radiation dose when using the metal filter unit 4. The radiation dose when using the metal filter unit 4 is calculated by the following (2). TIFF2025021646000002.tif16148I(E,x): Intensity of X-rays with energy E after attenuation (intensity after passing through metal filter part 4) I0(E): Initial intensity of energy E (intensity emitted from radiation source 2) μ(E): Linear attenuation coefficient of energy E in the material of the metal filter part 4 x: Distance that X-rays penetrate through a material (thickness of metal filter part 4) e: Napier's number

[0043] The dose may also be calculated using the following formula (3). TIFF2025021646000003.tif14160A: Detector area t: exposure time μ filer : Linear attenuation coefficient of metal filter part 4

[0044] The dose may be calculated by a method other than the above (2) and (3). For example, the dose may be calculated by adding a build-up term in consideration of scattered radiation, by considering that the beam is cone-shaped, or by using a Monte Carlo simulation.

[0045] When the user selects an imaging time using the input unit 6, the type of metal filter unit 4 is determined. The metal filter unit 4 is moved by the movement mechanism so that the metal filter unit 4 corresponding to the selected imaging time is positioned on the optical axis of the radiation source 2.

[0046] As described above, in the CT device 100 of the modified example 2, the type of the metal filter part 4 for each imaging time is different, and imaging conditions are stored in association with each imaging time so that the dose is the same or within a certain range. This makes it possible to set the metal filter part 4 that is optimal for the radiation irradiated from the radiation source 2, and effectively reduce metal artifacts.

[0047] The determined metal filter part 4 does not have to be automatically positioned by the movement mechanism. For example, the material and thickness of the metal filter part 4, and if each metal filter part 4 is numbered, the numbers may be displayed on the display unit 5, and the user may be allowed to position them. In this case, since there is no need to place multiple metal filter parts 4 or a movement mechanism in the CT device 100, the CT device 100 can be simplified and made smaller.

[0048] (Variation 3) Next, a CT device 100 according to a modified example 3 will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. In the modified example 1, the exposure time is adjusted according to the imaging time, but in the modified example 3, the number of accumulated images is changed.

[0049] Fig. 8 is a table showing an example of shooting conditions according to shooting time in Modification 3. Fig. 8 shows examples of shooting times of 1 min, 4 min, 27 min, and 36 min. As shown in Fig. 8, the integrated number of frames for shooting times of 1 min and 4 min is 1, but the integrated number of frames for shooting times of 27 min and 36 min is 3. Note that the binning is 3 for 1 min and 4 min, but 1 for 27 min and 36 min.

[0050] As described above, the CT device 100 of the third modification changes the binning in at least a part of each imaging time, and adjusts the number of accumulated images so that the dose is the same or in a certain range. This allows the imaging time and dose to be adjusted without changing the quality of the X-rays, such as the penetration ability or spectrum. In addition, when adjusting the exposure time, restrictions arise due to the specifications of the CT device 100, but when adjusting the number of accumulated images, there are no such restrictions, so the freedom of setting the imaging conditions for each imaging time increases.

[0051] (Variation 4) Next, a CT apparatus 100 according to a fourth modified example will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment, imaging is started under imaging conditions corresponding to the imaging time selected by the user, but in the fourth modified example, the imaging apparatus has a function of correcting the imaging time corresponding to the imaging time.

[0052] For example, the user selects 7 minutes from the four shooting times shown in Fig. 4. Then, the display unit 5 displays the shooting conditions corresponding to the selected shooting time of 7 minutes, as shown in Fig. 9(a). The user can change the shooting mode on this display screen.

[0053] When the user changes the shooting mode from standard to expert, the shooting mode changes to expert mode and each shooting condition can be modified as shown in Fig. 9(b). After modifying each shooting condition to a more appropriate one, the user presses the OK button, and the shooting conditions are changed to the modified ones, and shooting is started based on the modified shooting conditions.

[0054] In this way, the CT device 100 of the fourth modification can correct the preset imaging conditions. This allows fine correction according to the purpose of imaging, etc., and allows imaging under more optimal imaging conditions. Therefore, more optimal images can be obtained.

[0055] Second embodiment Next, a CT device 100 according to a second embodiment will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment, the imaging conditions are set so that the dose is the same or within a certain range at each imaging time. In addition to this, in the second embodiment, the imaging conditions are set so that the resolution for a long imaging time is equal to or higher than that for a short imaging time. The resolution is the resolution of the detector.

[0056] Fig. 10 is a table showing an example of the imaging conditions according to the imaging time in the second embodiment. In the example of Fig. 10, six examples of imaging times, 1 min, 2 min, 4.5 min, 9 min, 27 min, and 36 min, are shown. The dose of each imaging time is the same at 90,000.

[0057] The shooting conditions are set so that the resolution of a long shooting time is equal to or greater than that of a short shooting time. In other words, the resolution of a short shooting time is never higher than that of a long shooting time. In other words, when comparing shooting times of 1 minute and 2 minutes, the resolution is equal. On the other hand, when comparing shooting times of 1 minute and 4.5 minutes, or 2 minutes and 4.5 minutes, the resolution of 4.5 minutes is higher.

[0058] And because the resolution is linked to the binning, adjusting the resolution will also adjust the binning value. For example, in the example in Figure 10, the binning at a resolution of 500x500 is 3, whereas the binning at a resolution of 1500x1500 is adjusted to 2.

[0059] In this way, the CT device 100 in this embodiment has the same radiation dose at each imaging time, and the resolution of a long imaging time is equal to or higher than that of a short imaging time. Therefore, when the imaging time is long, a clear image can be obtained.

[0060] (Variation 5) A CT device 100 according to a fifth modified example will be described. The same configurations and functions as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the second embodiment, the imaging conditions are set so that the resolution increases stepwise as the set imaging time becomes longer. In the fifth modified example, the imaging conditions are set so that the number of views is the same or increases, instead of the resolution. The number of views refers to the number of data acquisition directions per revolution.

[0061] For example, as shown in FIG. 5, the number of views is set to 600 when the shooting time is 1 minute, 1200 when the shooting time is 2 minutes, 1800 when the shooting time is 12 minutes, and 2400 when the shooting time is 16 minutes, and the number of views is increased as the shooting time becomes longer.

[0062] In this way, when comparing the number of views for the set shooting time, the number of views for the longer ones is equal to or greater than that for the shorter ones, and the number of views increases stepwise as the shooting time gets longer. For the same radiation dose, the sharpness of the image increases as the number of views increases. Therefore, the sharpness of the image can be increased as the shooting time gets longer.

[0063] Third embodiment A CT apparatus 100 according to the third embodiment will be described. The same configurations and functions as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. In the third embodiment, the imaging time and imaging conditions are set according to the geometric magnification.

[0064] 11 is a block diagram showing the configuration of the control unit 7 in the third embodiment. In the third embodiment, the control unit 7 further includes a movement amount calculation unit 75, a geometric magnification calculation unit 76, and a table selection unit 77. The movement amount calculation unit 75 calculates the amount of movement of the object to be inspected A, the detector 3, etc., by the user via the input unit 6.

[0065] The geometric magnification calculation unit 76 calculates the distance (FCD) from the focal point of the radiation source 2 to the object A to be inspected and the distance (FDD) from the focal point of the radiation source 2 to the detector 3, taking into account the movement amount calculated by the movement amount calculation unit 75. Then, the geometric magnification calculation unit 76 calculates the geometric magnification (FCD / FDD) from the calculated FCD and FDD.

[0066] The table selection unit 77 selects a preset table corresponding to the geometric magnification. Fig. 12 is a diagram showing the contents of each preset table. The storage unit 73 stores a plurality of preset tables that provide optimal photographing conditions corresponding to the geometric magnification. The preset table is a group of photographing conditions set corresponding to a plurality of photographing times and each photographing time. The preset table is changed depending on the geometric magnification.

[0067] For example, as shown in Fig. 12, preset tables (1) and (2) are set. A value a is stored in the storage unit 73 as a threshold value. The table selection unit 77 selects the preset table (1) when the geometric magnification calculated by the geometric magnification calculation unit is smaller than a. On the other hand, the table selection unit 77 selects the preset table (2) when the geometric magnification calculated by the geometric magnification calculation unit is equal to or larger than a. In this embodiment, it is assumed that the preset table (2) is selected.

[0068] The display unit 5 displays the imaging time set in the preset table (2), and the user selects the desired imaging time from the displayed time. Since the preset table (2) is selected as the imaging condition, the metal filter part 4 is set to 0 mm, that is, imaging is performed without placing the metal filter part 4. Also, the tube voltage is not 200 kV, and if the user selects 2 min, the imaging condition is 101 kV.

[0069] In this way, the storage unit 73 stores a plurality of preset tables corresponding to the geometric magnification, and the user selects the shooting time corresponding to the geometric magnification. Therefore, shooting corresponding to the geometric magnification can be performed, and even an inexperienced user can obtain a clearer image.

[0070] It is not necessary to have two types of preset tables, and more may be provided to classify the range of geometric magnification more finely. In this case, the number of thresholds indicating the boundaries of each preset table, such as the first threshold, the second threshold, etc., may also be increased. This allows a clearer image to be obtained.

[0071] (Variation 6) Next, a CT device 100 according to a sixth modified example will be described. The same configurations and functions as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The imaging condition CT device 100 according to the sixth modified example also stores a plurality of preset tables, as in the third embodiment, and the table selection unit 77 selects a corresponding preset table according to the geometric magnification, similarly to the third embodiment.

[0072] However, in the sixth modification, the dose is set to be the same or within a certain range under any of the imaging conditions. The dose is set to be the same or within a certain range by adjusting any or all of the tube current, exposure time, number of integrated sheets, and metal filter portion 4. In other words, even if the preset table is different, the dose under each imaging condition is the same or within a certain range.

[0073] Fig. 13 is a diagram showing the imaging conditions for each preset table of Modification 6. As shown in Fig. 13, the conditions of the tube current and exposure time are different in each preset table, but the dose is the same at 40000. Note that, in the example of Fig. 13, the dose is adjusted to be the same depending on the tube current and exposure time, but the metal filter unit 4 or the number of accumulated sheets may be adjusted.

[0074] In this way, in the sixth modification, the dose is set to be the same or within a certain range regardless of the imaging conditions belonging to any of the preset tables by adjusting any or all of the tube current, exposure time, number of integrated frames, and metal filter unit 4. This allows the signal-to-noise ratio to be constant or the metal filter unit 4 to be set to be optimal for reducing metal artifacts regardless of the geometric magnification, so that the image quality improves as the imaging time becomes longer.

[0075] (Fourth embodiment) A CT device 100 according to a fourth embodiment will be described. The same configurations and functions as those of the third embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. In addition to the configuration of the third embodiment, the CT device 100 according to the fourth embodiment is configured so that the user can select an imaging mode according to the type of object A to be inspected, the purpose of imaging, and the like.

[0076] The storage unit 73 stores a plurality of shooting modes. For example, in addition to the standard mode, the storage unit 73 stores shooting modes for each type of the object A to be inspected and each shooting purpose. The type of the object A to be inspected includes the material such as plastic, weight, thickness, etc., and the storage unit 73 stores the shooting time and the shooting duration in association with each item. The shooting purposes include internal observation, external observation, dimensional measurement, image clarity for each purpose, etc., and the storage unit 73 stores the shooting time and the shooting duration in association with each item. For each shooting mode, shooting conditions suitable for the shooting mode are set according to the shooting time.

[0077] Fig. 14 is a diagram showing an example of switching of imaging modes in the fourth embodiment. As shown in Fig. 14, the storage unit 73 stores a heavyweight mode in addition to the standard mode. In the heavyweight mode, the storage unit 73 stores a plurality of preset tables corresponding to the geometric magnification. The doses at each imaging time in the preset table are set to be the same or within a certain range. In addition, the doses at each imaging time in different preset tables are also set to be the same or within a certain range.

[0078] The user can change the shooting mode via the input unit 6. When the user selects a shooting mode, a preset table corresponding to the shooting mode and the geometric magnification is determined. Then, the display unit 5 displays the shooting time stored in the determined preset table. The user selects the shooting time via the input unit 6. The shooting condition determination unit 74 determines the shooting condition corresponding to the shooting time selected by the user as the shooting condition.

[0079] In this way, in the CT apparatus 100 of the fourth embodiment, the user selects an imaging mode depending on the type of the object A to be inspected and the imaging purpose. The storage unit 73 stores a plurality of preset tables corresponding to the imaging modes and imaging conditions corresponding to each imaging time. This allows imaging to be performed under more suitable conditions, and the user can obtain an optimal image.

[0080] (Other embodiments) In this specification, an embodiment of the present invention has been described, but this embodiment is presented as an example and is not intended to limit the scope of the invention. The above-mentioned embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiment and its modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and gist of the invention. [Explanation of symbols]

[0081] 100 CT equipment 1 Examination table 11 XY mechanism 12 Rotating table 13 Lifting mechanism 2 Radiation source 3. Detector 4 Metal filter part 5 Display section 6 Input section 7 Control section 71 Examination table control unit 72 Radiation Source Control Section 73 Memory section 74 Shooting condition determination unit 75 Travel amount calculation section 76 Geometric magnification calculation section 77 Table Selection Section A. Inspection item

Claims

1. a storage unit that stores a plurality of imaging times required for imaging an object to be inspected by irradiating the object with radiation and imaging conditions that are preset according to each imaging time; A display unit that displays a plurality of the shooting times; an input unit that accepts a selection of the shooting time displayed on the display unit from a user; a photographing condition determination unit that determines the photographing condition corresponding to the photographing time received by the input unit as a photographing condition at the time of photographing; A CT apparatus comprising:

2. The imaging conditions are set so that the radiation dose value detected by the detector is the same or within a certain range at any one of the imaging times. The CT apparatus according to claim 1.

3. By changing the exposure time setting, the dose value is adjusted to be the same or within a certain range. The CT apparatus according to claim 2.

4. a plurality of metal filters provided between the radiation source and the object to be inspected, the metal filters adjusting a transmission dose of the radiation; The dose value is adjusted to be the same or within a certain range by changing the material and thickness of the metal filter portion. The CT apparatus according to claim 2.

5. By changing the setting of the cumulative number of sheets, the dose value is adjusted to be the same or within a certain range. The CT apparatus according to claim 2.

6. The photographing conditions are set so that a resolution set when the photographing time is long is equal to or higher than a resolution set when the photographing time is short.

3. A CT apparatus according to claim 1 or 2.

7. The photographing conditions are set so that the number of views set for the long photographing time is equal to or greater than the number of views set for the short photographing time.

3. A CT apparatus according to claim 1 or 2.

8. A geometric magnification calculation unit that calculates a geometric magnification; a table selection unit that selects a preset table corresponding to the geometric magnification; Further comprising: the storage unit stores a plurality of preset tables corresponding to each geometric magnification; In each preset table, a plurality of the photographing times and photographing conditions preset according to each photographing time are set, the geometric magnification calculation unit calculates the geometric magnification based on a distance from a focus of a radiation source to the object to be inspected and a distance from the focus of the radiation source to a detector; the table selection unit selects the preset table corresponding to the geometric magnification calculated by the geometric magnification calculation unit, the display unit displays a plurality of the shooting times set in the preset table selected by the table selection unit.

3. A CT apparatus according to claim 1 or 2.

9. The radiation dose is adjusted to be the same or within a certain range by changing any or all of the settings of the tube current, the exposure time, the number of sheets to be accumulated, and the metal filter unit. The CT apparatus according to claim 8.

10. The storage unit stores an imaging mode for each type of the object to be inspected and each imaging purpose, In each of the photographing modes, the photographing conditions are set according to a plurality of the photographing times, the input unit accepts an input of the shooting mode from the user; the display unit displays a plurality of shooting times corresponding to the shooting mode selected by the user.

3. A CT apparatus according to claim 1 or 2.

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