JP5865641B2 - X-ray CT apparatus and radiotherapy apparatus - Google Patents

Description

  Embodiments described herein relate generally to an X-ray CT apparatus (X-ray Computed Tomography: X-ray computed tomography apparatus) and a radiotherapy apparatus.

  An X-ray CT apparatus irradiates a subject with X-rays under preset imaging conditions, detects X-rays transmitted through the subject with a plurality of detection elements, and detects the detected X-rays as an electrical signal for each detection element. Are converted into projection data and collected as projection data, and an image is reconstructed based on the projection data.

  Although some exposure is unavoidable in diagnosis with an X-ray CT apparatus, prevention of overexposure is desired. Therefore, when setting imaging conditions with an X-ray CT apparatus, for example, an imaging plan support apparatus that displays a plurality of imaging plans and calculates an expected dose before imaging is used. Specifically, in the imaging plan support device of Patent Document 1, after selecting an imaging plan, the exposure dose when X-rays are irradiated under the finally determined imaging conditions is calculated, and when the reference value is exceeded. Warning.

JP 2009-66288 A

  Among the shooting conditions, there is a condition that can only be determined after selecting which shooting plan to use. Therefore, in the prior art, since the exposure dose is calculated at the timing immediately before the scan in which all imaging conditions are determined, it may be notified that the exposure dose exceeds the reference value immediately before the scan. Usually, in such a case, the operator resets the shooting conditions.

  For this reason, there is a demand for a technique that supports setting of imaging conditions so that excessive exposure can be avoided without resetting imaging conditions immediately before scanning in a diagnostic apparatus that involves exposure to a patient such as an X-ray CT apparatus. It was.

  Similarly, in a radiotherapy apparatus, there has been a demand for a technique that supports setting of irradiation conditions so that excessive irradiation can be avoided without resetting irradiation conditions immediately before irradiation.

In one embodiment, the X-ray CT apparatus performs imaging of a subject based on an imaging plan selected by an operator, and includes an imaging plan storage unit, an exposure dose prediction unit, and a display unit.
The shooting plan storage unit stores a plurality of shooting plans associated with shooting conditions.
The exposure dose prediction unit calculates an expected exposure dose for the subject when the imaging is performed with each imaging plan.
The display unit displays a list of imaging plans and displays information corresponding to the predicted exposure dose so that the information can be identified. As another embodiment, the display unit may be configured to select an imaging plan based on the expected exposure dose and display the selected imaging plan as a list.

In one embodiment, the radiotherapy apparatus irradiates radiation based on a treatment plan selected by an operator, and includes a treatment plan storage unit, an irradiation dose prediction unit, and a display unit.
The treatment plan storage unit stores a plurality of treatment plans associated with irradiation conditions.
The irradiation dose prediction unit calculates an expected irradiation dose when radiation is irradiated in each treatment plan.
The display unit displays a list of treatment plans and displays information corresponding to the expected irradiation dose in an identifiable manner. As another embodiment, the display unit may select a treatment plan based on the expected irradiation dose and display the selected treatment plan as a list.

1 is a block diagram showing the configuration of an X-ray CT apparatus in a first embodiment. FIG. 6 is a schematic diagram illustrating an example of a display of a list of photographing plans displayed as a list on the monitor of the display unit in the first embodiment. The schematic diagram which shows an example which identified and displayed the imaging | photography plan in which the estimated exposure dose exceeded the reference value in 1st Embodiment. The schematic diagram which shows an example which displayed only the imaging | photography plan whose estimated exposure dose is below a reference value, without displaying the imaging plan in which the estimated exposure dose exceeded the reference value in 1st Embodiment. The flowchart which shows the flow of operation | movement of the X-ray CT apparatus of 1st Embodiment. The block diagram which shows the structure of the radiotherapy apparatus in 2nd Embodiment. The flowchart which shows the flow of operation | movement of the radiotherapy apparatus of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus 20 in the first embodiment. As shown in FIG. 1, the X-ray CT apparatus 20 includes a gantry 22, an X-ray tube 24, a rotating unit 28, a bed 32, an X-ray detector 36, a high voltage generator 40, and a rotation driving unit. 44, a bed control unit 48, a system bus 52, a data acquisition system (hereinafter referred to as DAS) 56, a reconstruction unit 60, a system control unit 64, a storage unit 68, and an imaging plan support. Device 70.
The gantry 22 rotatably supports an annular or disk-shaped rotating unit 28.

  The bed 32 is inserted into an opening (not shown) provided at the center of the rotating unit 28, and the subject P is placed on the bed 32.

  In the rotating unit 28, the radiation port of the X-ray tube 24 and the X-ray detector 36 are arranged so as to face each other with the subject P in between.

  The X-ray detector 36 has a configuration in which multi-channel detection elements are arranged in an arc shape, and detects X-rays irradiated from the X-ray tube 24 and transmitted through the subject P.

  The rotation drive unit 44 drives the rotation unit 28 based on a drive control signal input from the system control unit 64, and moves the X-ray tube 24 and the X-ray detector 36 supported by the rotation unit 28 around the subject P. Rotate continuously with.

  The bed control unit 48 controls the position of the bed 32 based on the bed control signal input from the system control unit 64.

  The high voltage generator 40 is connected to a high voltage cable of the X-ray tube 24 via a slip ring (not shown). The high voltage generator 40 supplies a predetermined tube current and tube voltage to the X-ray tube 24 based on the X-ray control signal supplied from the system control unit 64.

  The system control unit 64 controls each unit of the X-ray CT apparatus 20 according to various setting conditions input from the input unit 80 described later. Further, the system control unit 64 is connected to a control unit (not shown) of the X-ray tube 24 and controls imaging using X-rays irradiated by the X-ray tube 24.

  The DAS 56 integrates an output from each detection element of the X-ray detector 36 with time, a multiplexer that takes the output of the integrator in a channel unit at high speed and serially, and an A that converts the output signal of the multiplexer into a digital signal. / D converter. The DAS 56 collects projection data reflecting the X-ray transmittance for each X-ray path detected by the X-ray detector 36 based on the data acquisition control signal input from the system control unit 64, and reconstructs it. Input to the unit 60 and the storage unit 68.

The reconstruction unit 60 performs reconstruction processing on the projection data collected for a plurality of slice planes of the subject P, and generates image data of the image of the subject P. The image data may be multi-slice image data or volume data. The volume data is three-dimensional image data, that is, image data in a thick range. For example, each voxel (each pixel) has a CT value or a pixel value that defines its luminance level.
The CT value (Computed Tomography Number) represents the X-ray absorption rate of a substance as a relative value with respect to a reference substance such as water.

  The storage unit 68 stores projection data collected for a plurality of slice planes of the subject P. The storage unit 68 stores the image data (or volume data) generated by the reconstruction unit 60 and inputs the image data (or volume data) to the display unit 78 in accordance with a command from the system control unit 64.

  The imaging plan support apparatus 70 includes, for example, the system bus 52, an imaging plan creation unit 72, an exposure dose prediction unit 74, a determination unit 76, a display unit 78, and an input unit 80.

  The input unit 80 includes input devices such as a keyboard, a mouse, a display panel, and selection buttons. Prior to the collection of projection data, the operator can input information on the subject P, select an imaging plan (to be described later), set projection data collection conditions, reconstruction conditions, image display conditions, and the like in the input unit 80. it can. The imaging conditions set in this way are input to the imaging plan creation unit 72 and the system control unit 64.

  The shooting plan creation unit 72 creates a plurality of shooting plans based on the shooting conditions input from the input unit 80. The shooting plan creation unit 72 stores a plurality of shooting plans associated with shooting conditions in this way, and also functions as a shooting plan storage unit. The shooting plan creation unit 72 inputs the created shooting plans to the display unit 78.

  The exposure dose prediction unit 74 calculates an expected exposure dose for each imaging plan for the subject P before selecting an imaging plan.

  The determination unit 76 acquires a dose threshold (hereinafter referred to as a reference value) set in accordance with the subject in order to avoid excessive exposure. When the operator does not set the reference value, the determination unit 76 calculates the reference value. The determination unit 76 determines whether or not the predicted exposure dose exceeds the reference value for each imaging plan, and inputs the determination result to the display unit 78.

  The display unit 78 displays a list of photographing plans created by the photographing plan creation unit 72 (on a monitor (not shown)). In addition, when displaying the list of the imaging plan list, the display unit 78 sets only the imaging plan in which the predicted exposure dose exceeds the threshold value as an identifying display mode. The display unit 78 adds display information such as patient information to the image data generated by the reconstruction unit 60 to generate display image data, and displays an image of the subject P based on the display image data. To do.

  FIG. 2 is a schematic diagram illustrating an example of a list of shooting plans displayed in a list on the monitor of the display unit 78 in the first embodiment. Hereinafter, a method for creating a shooting plan by the shooting plan creating unit 72 will be described.

  In imaging by the X-ray CT apparatus, one imaging is composed of a plurality of elements for each part, and imaging conditions are set for each element. Here, the “element” is a unit of a scanning operation performed under a single imaging condition. For each element, for example, the following items can be input as shooting conditions to the shooting plan creation unit 72 via the input unit 80.

  Specifically, the scan element number, the waiting time as a pause time from the end of the previous element to the start of the element, the scan method, the number of scans within the element, the tube voltage, the tube current, the diameter of the reconstruction field of view, X These are the scan time (rotation time) required for one rotation of the tube, the total scan time, and the imaging slice thickness.

  The photographing plan creation unit 72 creates a plurality of photographing plans having different main photographing conditions such as a scanning method within a range that satisfies the already inputted photographing conditions. In the following description, the scan was obtained by irradiating the subject P with X-rays, detecting the transmitted X-rays, and converting the detected X-rays for each detection element into electrical signals. It refers to the processing until the projection data is collected and recorded. Further, imaging refers to both the above scan and the operation of generating image data of the subject by image reconstruction processing after the scan.

  Examples of the scanning method include conventional scanning, helical scanning, RealEC (Real Exposure Control), VolumeEC (Volume Exposure Control), and the like.

  The conventional scan is a method in which the next scan is sequentially performed by moving the scan position by a predetermined amount in the Z-axis direction when the moving direction of the bed 32 is, for example, the Z-axis direction of the apparatus coordinate system.

  Helical scan is a method of collecting projection data while moving the bed 32 at a predetermined speed in synchronization with a change in projection angle and moving the scan position. In the helical scan method, the X-ray tube 24 and the X-ray detector 36 rotate around the subject P in a spiral shape.

  RealEC is a scan method in which tube current is modulated based on scano image data in order to reduce exposure dose. The scanogram is a preliminary image that is shot in advance for setting shooting conditions such as positioning. Specifically, based on the scanogram, the minimum value of the tube current at which all slices can be displayed as the same image SD is calculated, and current control is performed during the helical scan.

  The image SD (standard deviation) is defined as image noise included in a reconstructed image, and variation in CT values of a homogeneous phantom image is defined as a standard deviation.

  VolumeEC calculates the lowest tube current value from two directions in which all slices can be displayed in the same image SD based on the scan image, and performs current control during the helical scan.

  The scanogram may or may not have been shot when the list of shooting plans is created. After selecting a shooting plan, a scanogram may be taken as part of the shooting plan during execution of the shooting plan. Here, as an example, it is assumed that the shooting plan created by the shooting plan creation unit 72 includes uncertain shooting conditions such as a scan start position.

  In FIG. 2, a selection button 150 indicates that the conventional scan can be selected as the PLAN 1 of the photographing plan. In the dose display window 150x on the right side of the selection button 150, the predicted exposure dose calculated by the exposure dose prediction unit 74 is displayed later (see FIG. 3 described later).

  Similarly, the selection button 152 indicates that RealEC can be selected as PLAN2 of the shooting plan. In the dose display window 152x on the right side of the selection button 152, the expected exposure dose calculated by the exposure dose prediction unit 74 is displayed later (see FIG. 3 described later).

  Similarly, the selection button 154 indicates that Volume EC can be selected as the PLAN 3 of the photographing plan. In the dose display window 154x on the right side of the selection button 154, the expected exposure dose calculated by the exposure dose prediction unit 74 is displayed later (see FIG. 3 described later).

The situation explanation window 170 explains the current setting situation. In this example, it is shown that the expected exposure doses of the PLAN 1 to 3 of the imaging plan are being calculated.
The button 172 returns to the previous setting screen when it is selected by clicking or the like.

  FIG. 3 is a schematic diagram showing an example in which an imaging plan in which the predicted exposure dose exceeds the reference value is identified and displayed in the first embodiment. After the imaging plan creation unit 72 creates the list of imaging plans, the exposure dose prediction unit 74 calculates the expected exposure dose for each imaging plan for the subject P before selecting the imaging plan, and the calculation result is displayed on the display unit 78. input.

  Specifically, the exposure dose predicting unit 74 substitutes a condition for maximizing the exposure dose for an undetermined imaging condition before selecting an imaging plan, and sets an imaging condition determined before selecting an imaging plan. Use to calculate the expected exposure dose.

In calculating the exposure dose, here, as an example, CTDI (Computed Tomography Dose Index) and DLP (Dose Length Product) are used. CTDI without a subscript is a conceptual exposure dose per 1 cm slice, but in order to actually define various imaging conditions, the condition is represented by a subscript.
For example, CTDI ₁₀₀ has an integrated dose in a range of −50 mm to +50 mm of a dose profile of a slice generated by a 360 ° rotation of the radiation source, where D (z) is a dose profile in a perpendicular line to the slice plane. Divided by the product of the number of faces N and the slice thickness T. CTDI ₁₀₀ is expressed by, for example, the following formula (1).

(Z) of D (z) means a function of position coordinates in the Z-axis direction of the apparatus coordinate system of the X-ray CT apparatus 20. This Z-axis direction matches, for example, the moving direction of the bed 32. In the following description, as an example, the subject P is placed on the bed 32 so that the body axis direction of the subject P (the direction from the head to the foot along the extending direction of the spine in the upright posture) matches the Z-axis direction. It shall be placed on top.
If the value of CTDI ₁₀₀ at the center of the imaging range is CTDI _CEN and the average value of CTDI _{100 at} the four surroundings is CTDI _AVE , CTDI _W is expressed by the following equation.

CTDI _W = {CTDI _CEN / 3} + {CTDI _AVE × 2/3} (2)

CTDI _W means Wed weighted average.
In the case of conventional scanning, DLP is obtained by multiplying CTDI _W by, for example, slice thickness T and the number of detection element columns N _D in the X-ray detector 36. In the following example, CTDI _W and DLP are used as reference value indicators for avoiding excessive exposure, but other indicators such as CTDI _VOL and mSv (millisievert) may be used.

  The determination unit 76 determines for each imaging plan whether or not the expected exposure dose exceeds the reference value, and inputs the determination result to the display unit 78.

  The display unit 78 displays the predicted exposure dose input from the exposure dose prediction unit 74 in the dose display windows 150x, 152x, and 154x, respectively.

Further, when displaying the list of imaging plans, the display unit 78 changes the display mode so that only the imaging plans whose expected exposure dose exceeds the reference value are identified and displayed from the display state of FIG. In the example of FIG. 3, the predicted exposure dose exceeds the reference value only for the PLAN 1 of the imaging plan (“exceeding the reference value” means that at least one of CTDI _W and DLP exceeds the reference value). For this reason, the frame of the selection button 150 of PLAN1 and the dose display window 150x is made a dotted line and a thick line to distinguish it from PLAN2 and 3 of other imaging plans.

  This is merely an example of identification display. For example, identification display may be performed by displaying only the selection button 150 in a blinking manner, or by coloring only the selection button 150 to a chromatic color (such as red) different from other shooting plans. Alternatively, the warning sound may be played while displaying the identification, or the warning sound may be played without displaying the identification. The warning voice may be, for example, “Please do not select PLAN1 of the shooting plan because the exposure amount may exceed the reference value”.

  In the situation explanation window 170, the fact that the predicted exposure dose exceeds the reference value in the PLAN 1 of the imaging plan is explained and displayed as a situation.

  FIG. 4 is a schematic diagram showing an example in which only imaging plans whose expected exposure doses are below the reference value are displayed in a list without displaying the imaging plans whose expected exposure doses exceed the reference values in the first embodiment. . As shown in FIG. 4, the display unit 78 does not display an imaging plan in which the expected exposure dose exceeds the reference value when displaying the list of imaging plans after calculating the expected exposure dose (deletes it at the time of display). An imaging plan in which the exposure dose does not exceed the reference value may be displayed.

  After calculating the expected dose as shown in FIGS. 3 and 4, the operator can select the plan 2 (or plan 3) of the imaging plan by clicking the selection button 152 (or 154), for example. When a shooting plan is selected, a screen for setting detailed shooting conditions for the selected shooting plan is displayed (not shown), and the operator can set shooting conditions that have not been confirmed.

  FIG. 5 is a flowchart showing an operation flow of the X-ray CT apparatus according to the first embodiment. First, there are cases where other imaging is performed on the same subject P and cases where it is not performed as a stage before step S1 in FIG.

  In addition, there are a case where a scan image has been taken with respect to the same subject P and a case where it has not been taken as a previous stage of step S1. For example, when the next imaging plan is performed on the same subject P while viewing the result of the previous imaging, the first time even if the scanogram has not been captured before the selection of the first imaging plan. If a scano image is shot during the execution of the shooting plan, the scano image may have been acquired when the shooting plan is selected before the second shooting.

  Then, some imaging conditions such as information on the subject P (patient information) are input by the operator via the input unit 80.

A reference value for avoiding excessive exposure is arbitrarily set by the operator. When the reference value is not set by the operator, the determination unit 76 calculates the reference values CTDI _W and DLP by taking into account the information on the subject P and the imaging region information when the imaging region is fixed. . At this time, the determination unit 76 calculates a reference value so as not to exceed the irradiation dose recommended by ICRP (International Commission on Radiological Protection) or IEC (International Electrotechnical Commission).

  The operation of the X-ray CT apparatus will be described below according to the step numbers in the flowchart shown in FIG.

  [Step S1] The photographing plan creation unit 72 creates a plurality of photographing plans having different main photographing conditions such as a scanning method within a range satisfying the already inputted photographing conditions. Since this creation method has been described above with reference to FIG. 2, further description is omitted. The display unit 78 displays a list of shooting plans as shown in FIG. At this point, the shooting plan is not yet selected. Thereafter, the process proceeds to step S2.

  [Step S2] The exposure dose prediction unit 74 selects one imaging plan for which the expected dose has not been calculated (in the example of FIG. 2, any one of PLAN1 to PLAN3). Thereafter, the process proceeds to step S3. In addition, instead of sequentially calculating each of the imaging plans one by one as in the following example, a plurality of exposure dose prediction units 74 are provided, and the calculation of the expected exposure doses of the plurality of imaging plans is performed on the plurality of exposure dose prediction units 74. The calculation time may be shortened by calculating in parallel.

  [Step S3] The exposure dose prediction unit 74 determines whether or not a scanogram has already been taken for the same subject P. If a scano image has been taken, the process proceeds to step S4, and if not, the process proceeds to step S7. When there is a scanogram, the scan start position is generally uncertain. In this case, the expected dose is calculated by calculating the exposure dose for each scan start position and taking the maximum value (see steps S5 and S6 described later).

  [Step S4] The exposure dose prediction unit 74 determines whether or not the scan method of the imaging plan that is currently the target for calculating the expected exposure dose is either RealEC or VolumeEC. If it is RealEC or VolumeEC, the process proceeds to step S6. If not, the process proceeds to step S5.

  [Step S5] Here, as an example, the exposure dose prediction unit 74 calculates an expected exposure dose assuming that the scan method is a conventional scan.

  The number of millimeters to be moved from the scan start position in the Z-axis direction of the apparatus coordinate system (in this example, the movement direction of the bed 32 and the body axis direction of the subject P) is determined in step S1. It was previously determined as one of the shooting conditions. For example, consider a case where scanning is performed by moving 150 mm in the Z-axis direction.

  In this case, the exposure dose prediction unit 74 changes the position one-dimensionally in the Z-axis direction, for example, in increments of 1 centimeter, and out of all 150 mm ranges including the subject P, which range is the maximum exposure dose. Is calculated. Specifically, for example, the expected exposure dose may be calculated for each range of 150 millimeters. At this time, based on the information of the subject P such as height and weight, it may be calculated in which 150 millimeters the exposure dose is maximized using a known human physique model.

  The exposure dose prediction unit 74 calculates the scan range in which the exposure dose is maximized as described above with the whole body of the subject P as the target range, and assumes the end of the calculated scan range as the scan start position. In this way, the exposure dose prediction unit 74 obtains a condition that maximizes the exposure dose for the uncertain imaging conditions, and uses the obtained condition for calculating the exposure dose (the same applies to step S6). Thereafter, the process proceeds to step S8.

  [Step S6] The exposure dose prediction unit 74 calculates the scan range in which the exposure dose is maximized in the same manner as in step S5 for only the range of the subject P shown in the scanogram, and the calculated scan range Assume that the end is the scan start position. Thereafter, the process proceeds to step S10.

[Step S7] This step S7 is reached when there is no scanogram.
When there is no scanogram, the scan method of the imaging plan is not set to RealEC or VolumeEC, and the X-ray output (tube current or the like) has already been set in the imaging plan. In general, the tube voltage has been set to a predetermined value before step S1.

  In this case, the exposure dose prediction unit 74 provisionally determines the scan start position by assuming that the bed 32 is at the current position at the start of the scan. Specifically, for example, an area that is an irradiation range of the X-ray tube 24 at the current position of the bed 32 is assumed as a scan range, and one end thereof is assumed as a scan start position. Thereafter, the process proceeds to step S8.

  [Step S8] The exposure dose prediction unit 74 calculates the expected exposure dose of the imaging plan to be calculated. At this time, the conditions are used for the imaging conditions determined in the target imaging plan, but the conditions for maximizing the exposure dose obtained before step S7 are substituted for the indeterminate imaging conditions.

  A method for calculating an expected exposure dose when all the imaging conditions are fixed is a known technique according to Patent Document 1 or the like. However, in the present embodiment, in the known calculation method, the maximum exposure dose is set for an undetermined imaging condition. The point of substituting the condition is greatly different. Thereafter, the process proceeds to step S9.

  [Step S9] The exposure dose prediction unit 74 determines whether or not another imaging has already been performed on the same subject P as the subject P of the imaging plan currently displayed before step S1. judge. In the case of having been executed, the exposure dose prediction unit 74 calculates the total value of the actual exposure doses to the same subject P in all executed imaging as the accumulated exposure dose (integrated exposure dose).

  The exposure dose prediction unit 74 corrects the expected exposure dose by adding the cumulative exposure dose to the expected exposure dose calculated in step S8. The exposure dose prediction unit 74 inputs the corrected predicted exposure dose to the determination unit 76 and the display unit 78. The display unit 78 displays the predicted exposure dose input from the exposure dose prediction unit 74 in a dose display window (150x, 152x, 154x) (see FIG. 3). Thereafter, the process proceeds to step S10.

  [Step S10] The determination unit 76 determines whether or not the expected exposure dose of the imaging plan to be calculated exceeds the reference value set before step S1, and inputs the determination result to the display unit 78. If the expected exposure dose of the imaging plan exceeds the reference value, the process proceeds to step S11, and if not, the process proceeds to step S12.

  [Step S11] The display unit 78 changes the display mode of the radiographing plan input in step S10, that is, the radiographing plan in which the predicted exposure dose exceeds the reference value, to an identifying one. In this way, information corresponding to the predicted exposure dose (for example, information on whether or not the reference value is exceeded) is added to the display screen by discriminating the display mode of the imaging plan in which the predicted exposure dose exceeds the reference value. Is done. The identification display is as described above with reference to FIG.

  The display unit 78 may display the identification sound and play a warning sound, or may sound the warning sound without performing the identification display. Alternatively, the display unit 78 may display an imaging plan in which the expected exposure dose does not exceed the reference value without displaying the imaging plan in which the expected exposure dose exceeds the reference value (see FIG. 4). Thereafter, the process proceeds to step S12.

  [Step S12] The exposure dose prediction unit 74 determines whether or not the predicted exposure dose has been calculated for all the imaging plans created by the imaging plan creation unit 72 in step S1, and if all have been calculated, step S13. Proceed to When that is not right, it returns to step S2 and the exposure dose estimation part 74 calculates the expected exposure dose of another imaging plan.

  [Step S13] The operator selects one of the shooting plans on the screen of the display unit 78 via the input unit 80. After the selection of the shooting plan, the undetermined shooting conditions are determined by the operator, or an appropriate value is automatically calculated and set by the shooting plan creation unit 72.

  [Step S14] The system control unit 64 controls each part of the X-ray CT apparatus 20 based on the imaging conditions of the imaging plan selected and determined by step S13, and executes imaging. Specifically, X-rays emitted from the X-ray tube 24 pass through the subject P and are detected by the detection element of the X-ray detector 36. This process is performed by driving the rotation unit 28 by the rotation drive unit 44 and continuously rotating the X-ray tube 24 and the X-ray detector 36 supported by the rotation unit 28 around the subject P.

The DAS 56 collects projection data reflecting the X-ray transmittance for each X-ray path sequentially detected by the X-ray detector 36, and sequentially inputs the projection data to the reconstruction unit 60 and the storage unit 68. When the collection of the projection data is completed, the reconstruction unit 60 performs a reconstruction process on the collected projection data, generates image data (or volume data) of the subject P, and stores this in the storage unit 68. . The system control unit 64 causes the display unit 80 to display a desired cross section of the subject P obtained from the image data (or volume data) in response to an input to the input unit 80.
The above is the description of the operation of the X-ray CT apparatus 20 of the present embodiment, and the difference from the conventional one will be described below.

  In the prior art, if all the imaging conditions are not fixed, that is, the exposure dose cannot be calculated until the timing immediately before the scan, and the expected exposure dose cannot be displayed before the selection of the imaging plan. For this reason, after calculating the expected exposure dose based on all imaging conditions established immediately before the scan, it is notified that the expected exposure dose exceeds the reference value, and the imaging conditions may be reset.

  On the other hand, in the present embodiment, the estimated exposure dose is calculated before selecting an imaging plan by substituting and determining the maximum exposure dose for the uncertain imaging conditions, and the imaging plan exceeding the reference value is identified and displayed. To do. For this reason, the operator can reliably avoid overexposure and resetting of the imaging conditions only by selecting an imaging plan in which the expected exposure dose does not exceed the reference value according to the guide display. The expected exposure dose substitutes the maximum exposure dose for uncertain imaging conditions, so no matter which imaging plan is selected, the actual exposure dose will not exceed the expected exposure dose. is there.

  Further, the cumulative exposure dose in the same subject P is added to the expected exposure dose (step S9). Therefore, safety can be easily ensured from the viewpoint of overexposure even when multiple imaging plans are executed, for example, after imaging without contrast and imaging after administration of contrast medium to the same subject P. it can. In other words, from the viewpoint of exposure dose, it is possible to shorten and facilitate the time required for the operator to set the imaging conditions by reliably presenting only an imaging plan with no problem at an early stage.

  According to the embodiment described above, in a diagnostic apparatus that involves exposure to a patient such as an X-ray CT apparatus, setting of imaging conditions is supported so that excessive exposure can be avoided without resetting imaging conditions immediately before scanning. it can.

(Second Embodiment)
FIG. 6 is a block diagram showing a configuration of the radiation therapy apparatus according to the second embodiment. As shown in FIG. 6, the radiotherapy apparatus 200 includes a bed 208, a gantry 212, a stand 216, a treatment head 220 indicated by a broken line, a radioscopic part 224, a system control part 228, and a treatment plan support apparatus 232. With.

  In the second embodiment, an expected irradiation dose is calculated before selecting a treatment plan by substituting and finding a condition that maximizes the irradiation dose for uncertain irradiation conditions, and an irradiation plan exceeding a reference value is identified and displayed. To do. That is, in the second embodiment, the technical idea described in the first embodiment as an X-ray CT apparatus is applied to a radiation therapy apparatus, and the treatment plan support apparatus 232 is the same as that in the first embodiment. It functions in the same manner as the imaging plan support device 70.

  In FIG. 6, a bed 208 is movable in a predetermined direction under the control of the system control unit 228, and a subject P to be subjected to radiation therapy is placed thereon.

  The stand 216 includes a driving device (not shown) that supports the gantry 212 and rotates the gantry 212.

  The gantry 212 supports the treatment head 220 and the radioscopy unit 224 so as to face each other with the bed 208 interposed therebetween, and moves the treatment head 220 and the radioscopy unit 224 in a predetermined direction to adjust their positions. . The gantry 212 includes an electron gun (not shown) and the like inside.

  The treatment head 220 generates therapeutic radiation EB used for treatment of the subject P. Specifically, the treatment head 220 includes a waveguide guide 220a, a bending magnet 220b, a target 220c, and a collimator 220d.

  The electron beam EL generated by the electron gun in the gantry 220 is accelerated by the waveguide guide 220a and enters the bending magnet 220b. The bending magnet 220b causes the electron beam EL to collide with the target 220c by directing the direction of the incident electron beam EL downward. As a result, therapeutic radiation EB is generated. The generated therapeutic radiation EB is irradiated to the subject P after the irradiation shape and dose distribution are adjusted by the collimator 220d.

  The radiation fluoroscopic unit 224 detects the radiation that has passed through the subject P, and captures a fluoroscopic image for easily aligning the subject P and reconfirming the affected area.

  The system control unit 228 controls the entire radiotherapy apparatus 200 and causes the radiotherapy to be performed by causing each unit to function as described above. For example, the system control unit 228 rotates the gantry 212 by driving a driving device included in the stand 216 in accordance with an instruction from the operator. In addition, for example, the system control unit 228 performs predetermined image processing on an image captured by a camera (not shown) included in the radiological fluoroscopic unit 224 and displays the image subjected to the image processing on a display unit 248 described later. .

  The treatment plan support apparatus 232 includes, for example, a system bus 240, a treatment plan creation unit 242, an irradiation dose prediction unit 244, a determination unit 246, a display unit 248, and an input unit 250.

  The input unit 250 includes various input devices. The operator inputs information on the subject P, selects a treatment plan, sets irradiation conditions, and the like in the input unit 250. The irradiation condition thus set is input to the treatment plan creation unit 242 and the system control unit 228.

  The treatment plan creation unit 242 creates a plurality of different treatment plans based on the irradiation conditions input from the input unit 250. The treatment plan creation unit 242 stores a plurality of treatment plans associated with irradiation conditions in this way, and also functions as a treatment plan storage unit. The treatment plan creation unit 242 inputs the created treatment plans to the display unit 248.

  The irradiation dose prediction unit 244 calculates an expected exposure dose for each treatment plan for the subject P before selecting a treatment plan.

  The determination unit 246 acquires an irradiation dose threshold value (hereinafter referred to as a reference value) set according to the subject P in order to avoid excessive irradiation. The determination unit 246 determines for each treatment plan whether or not the expected irradiation dose exceeds the reference value, and inputs the determination result to the display unit 248.

  The display unit 248 displays a list of treatment plans created by the treatment plan creation unit 242 (on a monitor (not shown)). Further, the display unit 248 distinguishes the display mode of the treatment plan in which the expected irradiation dose exceeds the reference value when displaying the list of treatment plan lists.

  FIG. 7 is a flowchart showing an operation flow of the radiation therapy apparatus according to the second embodiment. First, as a previous stage of step S31 in FIG. 7, there are a case where another radiation treatment is being performed on the same subject P and a case where it is not being performed. In addition, a part of irradiation conditions such as information on the subject P (patient information) is input by the operator via the input unit 250.

The reference value of the irradiation dose for avoiding excessive irradiation is arbitrarily set by the operator. When the reference value is not set by the operator, the determination unit 246 automatically calculates and sets the reference value in consideration of the information on the subject P and the irradiation site information when the irradiation site is fixed.
Hereinafter, the operation of the radiation therapy apparatus 200 will be described according to the step numbers in the flowchart shown in FIG.

  [Step S31] The treatment plan creation unit 242 creates a plurality of treatment plans having different irradiation conditions within a range that satisfies the already set irradiation conditions. The display unit 250 displays a list of treatment plans (not shown). Thereafter, the process proceeds to step S32.

  [Step S32] The irradiation dose prediction unit 244 selects one treatment plan for which the expected irradiation dose has not been calculated. Thereafter, the process proceeds to step S33. Instead of sequentially calculating treatment plans one by one as in the following example, a plurality of irradiation dose prediction units 244 are provided, and the calculation of the predicted irradiation doses of a plurality of treatment plans is respectively performed on the plurality of irradiation dose prediction units 244. The calculation time may be shortened by calculating in parallel.

  [Step S <b> 33] The irradiation dose prediction unit 244 obtains a condition for maximizing the irradiation dose for uncertain irradiation conditions. Then, the irradiation dose prediction unit 244 substitutes the condition that maximizes the irradiation dose for the uncertain irradiation conditions, and calculates the predicted irradiation dose using the determined irradiation conditions. Thereafter, the process proceeds to step S34.

  [Step S34] The irradiation dose prediction unit 244 determines whether or not another radiation therapy has already been performed on the same subject P as the subject P of the treatment plan currently displayed before step S31. judge. In the case of having been executed, the irradiation dose prediction unit 244 calculates the total value of the actual irradiation doses to the same subject P in all executed radiotherapy as the cumulative irradiation dose.

  The irradiation dose prediction unit 244 corrects the predicted irradiation dose by adding the cumulative irradiation dose to the predicted irradiation dose calculated in step S33. The irradiation dose prediction unit 244 inputs the corrected predicted irradiation dose to the determination unit 246 and the display unit 248. The display unit 248 displays the predicted irradiation dose input from the irradiation dose prediction unit 244 as in the first embodiment. Thereafter, the process proceeds to step S35.

  [Step S35] The determination unit 246 determines whether or not the expected irradiation dose of the treatment plan to be calculated exceeds the reference value, and inputs the determination result to the display unit 248. If the expected irradiation dose of the treatment plan exceeds the reference value, the process proceeds to step S36, and if not, the process proceeds to step S37.

  [Step S36] The display unit 248 changes the display mode of the treatment plan input in step S35, that is, the treatment plan in which the predicted irradiation dose exceeds the reference value, to an identifying one. In this way, information corresponding to the expected irradiation dose (for example, information on whether or not it exceeds the reference value) is added to the display screen by discriminating the display mode of the treatment plan in which the expected irradiation dose exceeds the reference value. Is done. Since the identification display is the same as in FIG. 3 of the first embodiment, the illustration is omitted.

  Note that the display unit 248 may display the identification sound and play a warning sound, or may sound the warning sound without performing the identification display. Alternatively, the display unit 248 may display a treatment plan in which the expected irradiation dose does not exceed the reference value without displaying the treatment plan in which the expected irradiation dose exceeds the reference value. Thereafter, the process proceeds to step S37.

  [Step S37] The irradiation dose prediction unit 244 determines whether or not the predicted irradiation dose has been calculated for all the treatment plans created by the treatment plan creation unit 242 in step S1, and if all have been calculated, step S38. Proceed to When that is not right, it returns to step S32 and the irradiation dose estimation part 244 calculates the estimated irradiation dose of another treatment plan.

  [Step S38] The operator selects one of the treatment plans via the input unit 250 on the screen of the display unit 248. After selection of a treatment plan, uncertain irradiation conditions are determined.

  [Step S39] The system control unit 228 controls each unit of the radiotherapy apparatus 200 based on the irradiation conditions of the treatment plan selected and determined up to step S38, and performs radiotherapy (irradiation of the subject P with an electron beam). Is executed. The above is the description of the operation of the second embodiment.

  As described above, in the second embodiment, the treatment dose exceeding the reference value is calculated by calculating the expected radiation dose before selecting the treatment plan by obtaining and substituting the maximum radiation dose for the uncertain radiation conditions. Is displayed. Therefore, the operator can reliably avoid over-irradiation and re-setting of the irradiation conditions only by selecting a treatment plan in which the expected irradiation dose does not exceed the reference value according to the guide display.

  Further, the cumulative irradiation dose in the same subject P is added to the predicted exposure dose. Therefore, safety can be ensured from the point of excessive irradiation even when radiotherapy is performed a plurality of times on the same subject P.

  According to the embodiment described above, in the radiotherapy apparatus, setting of irradiation conditions can be supported so that excessive irradiation can be avoided without resetting irradiation conditions immediately before irradiation.

(Supplementary items of the embodiment)
[1] In the first embodiment, the scan start position is given as an example in steps S5 and S6 as an uncertain imaging condition. The embodiment of the present invention is not limited to such an aspect. Even when other parameters exist as uncertain imaging conditions, a condition that maximizes the exposure dose may be calculated in the same manner, and the expected exposure dose may be calculated by substituting it.

  [2] In the first embodiment, an example has been described in which, when the expected exposure dose is calculated, a condition that maximizes the exposure dose is calculated for the uncertain imaging conditions and is used instead. The embodiment of the present invention is not limited to such an aspect.

  For example, when there are a large number of parameters for unconfirmed imaging conditions, a value that is, for example, 98%, 95%, or 90% of the maximum exposure dose is calculated for each unconfirmed imaging condition. It may be substituted as a condition. This is because, when there are a large number of parameters of the unconfirmed imaging conditions, it is considered that the probability that the condition for maximizing the exposure dose is determined after selection of the imaging plan is low for all the unconfirmed imaging conditions. Similarly, in the second embodiment, a value that is, for example, 98%, 95%, or 90% of the maximum irradiation dose is calculated for uncertain irradiation conditions, and the calculated value is used as a condition that the exposure dose is substantially maximum. May be.

  [3] In the first embodiment, examples of CTDI and DLP have been described as reference values for avoiding excessive exposure. The embodiment of the present invention is not limited to such an aspect. For example, other reference doses such as a limit dose that burns the skin and a limit dose that cuts out the hair may be used. Furthermore, the operator may be notified in stages according to the level by checking the exposure dose in stages using the respective reference values.

  [4] In the first embodiment, an example has been described in which an imaging plan in which the predicted exposure dose exceeds the reference value is identified and displayed. The embodiment of the present invention is not limited to such an aspect. By identifying and displaying an imaging plan whose expected exposure dose does not exceed the reference value, it is possible to distinguish (identify) on the screen an imaging plan that is surely below the reference value and other imaging plans. . The same applies to the second embodiment.

  [5] When uncertain imaging conditions are included as in the first embodiment, the expected exposure dose is calculated by obtaining and substituting a condition that maximizes the exposure dose, and is surely below the reference value. The technique for discriminating the imaging plan and the other imaging plan can be applied to a diagnostic apparatus other than the X-ray CT apparatus. For example, X-ray diagnosis that detects X-rays transmitted through a subject with a plurality of detection elements arranged in a matrix and generates an image so that each pixel has a luminance corresponding to the X-ray detection amount for each detection element. It is also applicable to the device.

  [6] In the second embodiment, an example in which an electron beam is irradiated is described as an example of a radiation therapy apparatus. The embodiment of the present invention is not limited to such an aspect. The technical idea of the second embodiment can also be applied to a radiation therapy apparatus that uses other radiation such as X-rays.

  [7] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

20 X-ray CT device 22 Gantry 24 X-ray tube 28 Rotating unit 32 Couch 36 X-ray detector 40 High voltage generator 44 Rotating drive unit 48 Couch controlling unit 52 System bus 56 DAS
60 Reconstruction Unit 64 System Control Unit 68 Storage Unit 70 Imaging Plan Support Device 72 Imaging Plan Creation Unit 74 Exposure Dose Prediction Unit 76 Determination Unit 78 Display Unit 80 Input Units 150, 152, 154 Selection Buttons 150x, 152x, 154x Dose Display Window 170 Situation Explanation Window 200 Radiation Therapy Device 208 Bed 212 Gantry 216 Stand 220 Treatment Head 220a Waveguide Guide 220b Bending Magnet 220c Target 220d Collimator 224 Radioscopy Unit 228 System Control Unit 232 Treatment Plan Support Device 240 System Bus 242 Treatment Plan Creation Unit 244 Irradiation dose prediction unit 246 Determination unit 248 Display unit 250 Input unit EB Treatment radiation EL Electron beam P Subject

Claims (7)

In an X-ray CT apparatus that performs imaging of a subject based on an imaging plan selected by an operator,
A shooting plan storage unit that stores a plurality of the shooting plans associated with shooting conditions;
An exposure dose prediction unit for calculating an expected exposure dose for the subject when imaged with each imaging plan;
A determination unit that obtains a threshold value of the exposure dose and determines whether or not the predicted exposure dose exceeds the threshold value for each imaging plan;
A display for displaying a list of the shooting plans ;
With
The exposure dose prediction unit substitutes a condition for maximizing the exposure dose for uncertain imaging conditions, and uses the determined imaging conditions to calculate the expected exposure dose for each imaging plan for the subject. Calculate each before selecting a shooting plan,
The display unit displays the imaging plan so that the imaging plan in which the expected exposure dose exceeds the threshold value is in an identifying manner,
The uncertain imaging condition is an imaging condition related to a scan start position.
X-ray CT system. In an X-ray CT apparatus that performs imaging of a subject based on an imaging plan selected by an operator,
A shooting plan storage unit that stores a plurality of the shooting plans associated with shooting conditions;
An exposure dose prediction unit for calculating an expected exposure dose for the subject when imaged with each imaging plan;
A determination unit that obtains a threshold value of the exposure dose and determines whether or not the predicted exposure dose exceeds the threshold value for each imaging plan;
A display unit for displaying the shooting plan;
With
The exposure dose prediction unit substitutes a condition for maximizing the exposure dose for uncertain imaging conditions, and uses the determined imaging conditions to calculate the expected exposure dose for each imaging plan for the subject. Calculate each before selecting a shooting plan,
The display unit displays the imaging plan in which the expected exposure dose does not exceed the threshold;
The uncertain imaging condition is an imaging condition related to a scan start position.
X-ray CT apparatus. In the case where there is an imaging performed for the same subject before the calculation of the predicted exposure dose, the exposure dose prediction unit determines that the subject in the performed imaging at the time of the calculation of the expected exposure dose. The X-ray CT apparatus according to claim 1 , wherein the exposure dose is added to the expected exposure dose. Further comprising a bed on which the subject is movably mounted;
When the scano image used for setting the imaging condition is not imaged before the operator selects the imaging plan, the exposure dose prediction unit is in the X-ray irradiation range at the current position of the bed. The X-ray CT apparatus according to any one of claims 1 to 3 , wherein the expected exposure dose is calculated by assuming an area as a scan range and using one end thereof as a scan start position . The scano image used for setting the radiographing conditions has been captured before the operator selects the radiographing plan, and the radiographing plan modulates the tube current based on the data of the scanano image, thereby exposing the exposure dose. If the scan method is to reduce the exposure dose, the exposure dose prediction unit calculates the scan start position that maximizes the exposure dose within the region indicated by the scanogram, and then uses the calculated scan start position as one of the imaging conditions. The X-ray CT apparatus according to any one of claims 1 to 3, wherein the expected exposure dose is calculated. In a radiotherapy apparatus that emits radiation based on a treatment plan selected by an operator,
A treatment plan storage unit that stores a plurality of the treatment plans associated with irradiation conditions;
An irradiation dose prediction unit for calculating an expected irradiation dose when each of the treatment plans is irradiated with radiation, and
A determination unit that obtains a threshold value of irradiation dose and determines whether or not the predicted irradiation dose exceeds the threshold value for each treatment plan;
A display for displaying a list of the treatment plans;
With
The irradiation dose prediction unit substitutes a condition that maximizes the irradiation dose for uncertain irradiation conditions, and uses the determined irradiation conditions to calculate an expected irradiation dose for each treatment plan for the subject. Each calculated before selecting the treatment plan,
The display unit displays the treatment plan so that the treatment plan in which the expected irradiation dose exceeds the threshold value is in an identifying manner,
The uncertain irradiation condition is an irradiation condition related to a scan start position.
Radiation beam therapy system. In a radiotherapy apparatus that emits radiation based on a treatment plan selected by an operator,
A treatment plan storage unit that stores a plurality of the treatment plans associated with irradiation conditions;
An irradiation dose prediction unit for calculating an expected irradiation dose when each of the treatment plans is irradiated with radiation, and
A determination unit that obtains a threshold value of irradiation dose and determines whether or not the predicted irradiation dose exceeds the threshold value for each treatment plan;
A display unit for displaying the treatment plan;
With
The irradiation dose prediction unit substitutes a condition that maximizes the irradiation dose for uncertain irradiation conditions, and uses the determined irradiation conditions to calculate an expected irradiation dose for each treatment plan for the subject. Each calculated before selecting the treatment plan,
The display unit displays the treatment plan in which the expected irradiation dose does not exceed the threshold;
The uncertain irradiation condition is an irradiation condition related to a scan start position.
Radiation beam therapy system.

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