JP5280116B2 - Scan condition determining apparatus, medical system, and scan condition determining method - Google Patents

Description

  The present invention relates to a scan condition determining device for determining a scan condition, a medical system having the scan condition determining device, and a scan condition determining method for determining a scan condition.

If the quality of an image taken with the MRI system is not very good, the operator may want to change the parameter value of the scan parameter and re-photograph under new scanning conditions. However, if the parameter value is changed unnecessarily, the image quality may deteriorate. Therefore, there is known an MRI apparatus capable of presenting to an operator which scan parameter affects what image quality (see Patent Document 1).
JP-A-8-336504

  However, the method disclosed in Japanese Patent Laid-Open No. 8-336504 has a problem that it is necessary for the operator himself to change the parameter value of the scan parameter, which places a burden on the operator.

  In view of the above circumstances, the present invention provides a scan condition determining device that can easily determine a new scan condition, a medical system to which the scan condition determining device is applied, and a scan condition determining method for determining a scan condition. The purpose is to do.

The scan condition determining device of the present invention is a scan condition determining device for determining a scan condition when scanning a subject,
Display means;
Display control means for controlling the display means so that a plurality of items related to the image obtained by scanning the subject are displayed on the display means;
Item selection means for selecting one or more items among the plurality of items according to the operation of the operator;
According to the item selected by the item selection means, the scan condition determination means for determining a new scan condition by changing the parameter value of any one of the plurality of scan parameters of the scan condition,
have.

  The medical system of the present invention has the scan condition determining apparatus of the present invention.

The scan condition determination method of the present invention is a scan condition determination method for determining a scan condition when scanning a subject,
A display step of displaying on the display means a plurality of items related to the image obtained by scanning the subject;
An item selection step for selecting one or more of the plurality of items in response to an operation of the operator;
According to the item selected in the item selection step, a scan condition determination step for determining a new scan condition by changing the parameter value of any one of the plurality of scan parameters of the scan condition,
have.

  The scan condition determining apparatus of the present invention displays a plurality of items related to an image on a display unit, and performs a new scan based on an item selected according to an operation of an operator among the displayed items. The conditions are determined. Therefore, it is possible to easily provide new scanning conditions.

  The best mode for carrying out the invention will be described below in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention.

  FIG. 1 is a block diagram of an MRI (Magnetic Resonance Imaging) system 1 according to an embodiment of the present invention.

  The MRI system 1 includes an MR apparatus 10, a control apparatus 20, and an operation apparatus 30.

  The MR apparatus 10 collects data from the subject 11 and sends the collected data to the control apparatus 20.

  The control device 20 includes MR device control means 21 for controlling the operation of the MR device 10 and image reconstruction means 22 for processing data from the MR device 10 and reconstructing an image. The reconstructed image is sent to the operation device 30.

  The operation device 30 sends a command to the control device 20 or determines a new scan condition as will be described later. The operation device 30 includes a monitor 31, a keyboard 32, a mouse 33, and an operation device main body 34.

  FIG. 2 is a diagram illustrating functional blocks of the operation device main body 34.

  The operation device main body 34 includes scan condition setting means 41 to scan condition selection means 48. Hereinafter, each block will be described.

  The scan condition setting unit 41 sets the scan condition of the subject 11 according to the operation of the operator 29 (see FIG. 1).

  The display control means 42 includes an item display control unit 421, an image display control unit 422, and a scan condition display control unit 423.

  The item display control unit 421 controls the monitor 31 so that a plurality of items (see FIG. 6) described later are displayed on the monitor (display unit) 31.

  The image display control unit 422 controls the monitor 31 so that the reconstructed image is displayed on the monitor 31.

  The scan condition display control unit 423 controls the monitor 31 so that the scan condition of the subject 11 is displayed on the monitor 31. Further, the scan condition display control unit 423 controls the monitor 31 so that the monitor 31 also displays an SNR (Signal to Noise Ratio) ratio and an imaging time to be described later.

  The storage unit 43 includes a changed scan parameter storage unit 431 and a scan condition storage unit 432. The changed scan parameter storage unit 431 stores a table (see FIG. 8) that defines which scan parameter parameter value is changed. The scan condition storage unit 43 stores scan conditions.

  The item selection means 44 selects one item from a plurality of items (see FIG. 6 described later) according to the operation of the operator 29.

  The scan condition determining unit 45 determines a new scan condition. The scan condition determining unit 45 includes a changed scan parameter determining unit 451 and a parameter value changing unit 452. The changed scan parameter determination unit 451 refers to the table (see FIG. 8) stored in the changed scan parameter storage unit 431, and determines the scan parameter whose parameter value is changed according to the item selected by the item selection unit 44. The parameter value changing unit 452 changes the parameter value of the scan parameter determined by the changed scan parameter determining unit 451.

  The SNR ratio calculation means 46 calculates the ratio between the SNR of an image obtained using a scan condition C0 (see FIG. 4) described later and the SNR of an image obtained using a new scan condition.

  The shooting time calculation unit 47 calculates the shooting time.

  The scan condition selection unit 48 selects any one of a plurality of scan conditions according to the operation of the operator 29.

  Next, the processing flow of the MRI system 1 shown in FIG. 1 will be described.

  FIG. 3 is an example of a flowchart of the MRI system 1 in the first embodiment.

  In step S <b> 11, the operator 29 (see FIG. 1) operates the keyboard 32 and / or mouse 33 (see FIG. 1) to input scan conditions for scanning the subject 11.

  FIG. 4 is an example of scan conditions for the subject 11.

The scan condition has a plurality of scan parameters. The meaning of each scan parameter symbol is as follows.
TE: Echo time TR: Repetition time BW: Bandwidth
Freq: Number of pixels in the frequency encoding direction
Phase: Number of pixels in the phase encoding direction NEX: Number of additions (number of repetitions)
FOV: imaging area ST: slice thickness SP: spacing between adjacent slices

  The above scan parameters are parameters directly set by the operator 29. When the operator 29 inputs the parameter value of each scan parameter using the keyboard 32 and / or the mouse 33, the scan condition determining means 41 (see FIG. 2) uses the parameter value input by the operator 29 as each scan parameter. Determine the parameter value. In this way, the scan condition C0 for the subject 11 is set.

  When the scanning condition C0 is set, the photographing time Time is also calculated. The imaging time Time is calculated from the parameter value of the scan parameter NEX. In FIG. 4, the shooting time Time = 4 minutes 21 seconds.

  The scan condition C0 shown in FIG. 4 is stored in the scan condition storage unit 432 (see FIG. 2). Thereafter, the process proceeds to step S12.

  In step S12, the operator 29 operates the keyboard 32 and / or the mouse 33 to input a scan execution command for scanning the head 11a of the subject 11. When the operator 29 inputs a scan execution command, the control device 20 receives the scan execution command and controls the MR apparatus 10 so that the head 11a of the subject 11 is scanned according to the scan condition C0 shown in FIG. Control. As the head 11 a of the subject 11 is scanned, the receiving coil 12 collects data of the head 11 a of the subject 11. The collected data is transmitted to the control device 20. The control device 20 reconstructs an image from the collected data. The reconstructed image is sent to the operation device main body 34. Thereafter, the process proceeds to step S13.

  In step S <b> 13, the image display control unit 422 (see FIG. 2) controls the monitor 31 so that the reconstructed image sent to the operation device main body 34 is displayed on the monitor 31.

  FIG. 5 is an example of the display screen 310 of the monitor 31 that displays the reconstructed image.

  On the display screen 310, the reconstructed image 311 is displayed. After the image 311 is displayed, the process proceeds to step S14.

  The operator 29 refers to the image 311 displayed on the display screen 310, and whether the image 311 has a good image quality (for example, SNR, spatial resolution), is shorter than the shooting time taken to capture the image 311. Whether or not the subject 11 is to be imaged again at the imaging time is examined.

  If the operator 29 feels that the image quality (eg, SNR, spatial resolution) of the image 311 is not as good as expected or if the imaging time is long, a new scan different from the scan condition C0 in FIG. Sometimes you want to shoot under certain conditions. However, the operator 29 himself often does not sufficiently know which parameters of the scanning conditions are related to the image quality (for example, SNR, spatial resolution) and which parameters are related to the imaging time. Therefore, new scanning conditions that can improve the image quality (for example, SNR, spatial resolution) and the photographing time can be shortened with the knowledge of only the operator 29 itself as compared with the scanning conditions C0 of FIG. It is difficult to obtain new scanning conditions. Therefore, in the first embodiment, new scanning conditions and imaging time that can improve image quality (for example, SNR, spatial resolution) without the operator 29 having sufficient knowledge are shortened. Therefore, it is possible to easily obtain new scanning conditions that can be performed. Hereinafter, how the new scan condition is obtained will be described.

  As shown in FIG. 5, a new scan condition button 313 is displayed on the left side of the image 311 in addition to the cancel button 312 for ending the program. The new scan condition button 313 is a button for executing software for obtaining a new scan condition. Since the image quality of the image 311 (for example, SNR, spatial resolution) is not as good as expected, the operator 29 wants to take a picture under new scanning conditions for obtaining a high quality image, or a little more. When the user wants to perform shooting under a new scanning condition that allows shooting in a short shooting time, the user clicks a new scanning condition button 313. When the new scan condition button 313 is clicked, the process proceeds from step S14 to step S16.

  If the new scan condition button 313 is not clicked, the process proceeds from step S14 to step S15, and it is determined whether or not the cancel button 312 is clicked. If the cancel button 312 is clicked, the program ends. On the other hand, if the cancel button 312 is not clicked, the process returns from step S15 to step S14. Therefore, the loop of steps S14 and S15 is repeatedly executed until either one of the cancel button 312 and the new scan condition button 313 is clicked. If the new scan condition button 313 is clicked in step S14, the process proceeds to step S16.

  In step S16, in response to clicking of the new scan condition button 313, the item display control unit 421 (see FIG. 2) controls the monitor 31 so that a plurality of items are displayed on the monitor 31 (FIG. 6).

  FIG. 6 is a diagram illustrating an example of a display screen of the monitor 31 that displays a plurality of items.

In the lower left area 314 of the display screen 310, a plurality of items related to the image 311 are displayed. In the first embodiment, the following three items (1) to (3) are displayed.
(1) I want to shorten the shooting time.
(2) I want to increase the SNR.
(3) I want to increase the spatial resolution.

(1) is an item of photographing time. (2) and (3) are items relating to image quality. On the left side of each item, check boxes CB1, CB2, and CB3 are displayed. An accept button 315 and a cancel button 316 are displayed at the lower right of the display screen 310. After the screen 310 shown in FIG. 6 is displayed, the process proceeds to step S17.

  When the operator 29 wishes to shorten the shooting time, the operator 29 inputs a check in the shooting time check box CB1. If the operator 29 wants to improve the SNR for the image 311, he / she inputs a check into the SNR check box CB 2 and wants to improve the spatial resolution. Enter a check in CB3. FIG. 6 shows a state in which a check is input to the shooting time check box CB1. When the operator 29 clicks the accept button 315 in a state where a check is input in any of the check boxes CB1 to CB3, the item selection unit 44 (see FIG. 2) has the item in which the check is input in the check box. Select. For example, in FIG. 6, since the shooting time check box CB1 is checked, when the accept button 315 is clicked, the item selection means 44 selects the item “I want to shorten the shooting time”.

  If no item is selected, the process proceeds to step S18 to determine whether or not the cancel button 316 is clicked. When the cancel button 316 is clicked, the program ends. On the other hand, if the cancel button 316 is not clicked, the process returns to step S17, and the loop of steps S17 and S18 is repeatedly executed. If any of the three items is selected in step S17, the process proceeds to step S19.

  In step S19, according to the item selected by the item selection unit 44, the scan condition determination unit 45 (see FIG. 2) determines a new scan condition different from the scan condition C0 of FIG. Specifically, when the item selection unit 44 selects the item “I want to shorten the shooting time”, the scan condition determination unit 45 determines a new scan condition that can reduce the shooting time. When the item selection unit 44 selects the item “I want to increase the SNR”, the scan condition determination unit 45 determines a new scan condition that can increase the SNR. Further, when the item selection unit 44 selects the item “I want to increase the spatial resolution”, the scan condition determination unit 45 determines a new scan condition that can increase the spatial resolution.

  FIG. 7 is a diagram illustrating an example of a flow of scan condition determination executed in step S19.

  The scan condition determination unit 45 determines a new scan condition by changing the parameter value of one or more scan parameters among the plurality of scan parameters of the scan condition of FIG. In the following, when the item “I want to shorten the imaging time”, the item “I want to increase the SNR”, and the item “I want to increase the spatial resolution” are selected, how new scanning conditions are determined These will be described in order.

(A) When “I Want to Reduce Shooting Time” is selected In step S191, the changed scan parameter determining unit 451 (see FIG. 2) refers to the table stored in the changed scan parameter storage unit 431, and the process shown in FIG. A scan parameter whose parameter value is changed is determined from a plurality of scan parameters included in the scan condition C0.

  FIG. 8 is a diagram illustrating an example of a table stored in the changed scan parameter storage unit 431.

  The table includes an item column and a changed scan parameter column in which the parameter value is changed.

  For the item “I want to shorten the shooting time”, two columns A1 and A2 are provided in the column of changed scan parameters. In column A1, “NEX” is described, and in column A2, “NEX + Phase” is described. “NEX” means that the parameter to be changed is only NEX. “NEX + Phase” means that Phase is added to the parameter to be changed, and the parameter to be changed is NEX and Phase. Of the columns A1 and A2, the changed scan parameter determining unit 451 first determines only “NEX” as the scan parameter to be changed according to the contents described in the column A1. Thereafter, the process proceeds to step S192.

  In step S192, the parameter value changing unit 452 (see FIG. 2) changes the parameter value of the scan parameter determined in step S191. In step S191, since only “NEX” is determined to be a parameter to be changed, only the NEX parameter value is changed. The parameter value changing unit 452 changes the NEX parameter value so that the photographing time is shorter than the scanning condition C0 in FIG. In the scanning condition C0 of FIG. 4, since NEX = 3, the shooting time can be shortened by changing NEX to a value smaller than 3. However, in the first embodiment, NEX can take only integer values. Therefore, the NEX parameter value that can shorten the photographing time as compared with the scanning condition of FIG. 4 is an integer value smaller than 3, that is, NEX = 2 or NEX = 1. Therefore, when the parameter value changing unit 452 selects NEX = 2 or NEX = 1, it is possible to obtain a scan condition that makes the photographing time shorter than the scan condition C0 of FIG. In the first embodiment, the parameter value changing unit 452 has a value closest to the NEX value (NEX = 3) defined by the scan condition C0 in FIG. 4 among NEX = 2 or NEX = 1. And determined as a parameter value. The value closest to NEX = 3 is NEX = 2. Therefore, the parameter value changing unit 452 changes the value of NEX (NEX = 3) defined by the scan condition C0 in FIG. 4 to NEX = 2. Thereby, the scan condition determining means 45 determines a scan condition in which the value of NEX (NEX = 3) is replaced with NEX = 2 in the scan condition C0 of FIG. 4 as a new scan condition. In this way, new scan conditions are determined.

  FIG. 9 is a diagram in which the scan condition C0 of FIG. 4 and the new scan condition Ct1 replaced with NEX = 2 are shown side by side.

  The new scan condition Ct1 is the same as the scan condition C0 except for the value of NEX. After changing the parameter value in this way, the process proceeds to step S193.

In step S193, the SNR ratio calculating means 46 (see FIG. 2) uses the SNR (= SNR0) of the image obtained using the scan condition C0 and the SNR (= SNR1) of the image obtained using the new scan condition Ct1. A ratio R01 is calculated. R01 is calculated from the following equation (1).
R01 = (SNR1 / SNR0) × 100 (1)

  The value of the term (SNR1 / SNR0) in equation (1) can be calculated if the BW and NEX values of the scan conditions C0 and Ct1 are known. Therefore, the ratio R01 can be calculated by using the equation (1). Here, the ratio R01 = 82% (see FIG. 9). Therefore, it can be seen that when the subject 11 is scanned under the new scan condition Ct1, the SNR is 18% lower than when scanned under the scan condition C0. After calculating the SNR ratio R01, the process proceeds to step S194.

  In step S194, the shooting time calculation unit 47 (see FIG. 2) calculates a shooting time Time required for shooting using the new scan condition Ct1. The imaging time Time of the new scan condition Ct1 is 2 minutes 53 seconds (see FIG. 9). Therefore, it can be seen that the shooting time Time can be shortened by changing from NEX = 3 to NEX = 2. After the photographing time Time is determined, the process proceeds to step S195.

  In step S195, the changed scan parameter determination unit 451 determines whether or not to change the parameter value of any scan parameter with respect to the scan parameter of the new scan condition Ct1. Referring to FIG. 8, when the item “I want to shorten the shooting time” is selected, column A2 (see FIG. 8) stipulates that “Phase” be added to the parameter to be changed. However, only the parameter value “NEX” is changed in the new scan condition Ct1. Therefore, the changed scan parameter determination unit 451 determines to change the parameter value of Phase, and the process returns to step S192.

  In step S192, the parameter value changing unit 452 (see FIG. 2) changes the parameter value of “Phase” for the new scan condition Ct1. In this case, the parameter value changing unit 452 changes the parameter value of “Phase” so that the imaging time is shorter than the new scanning condition Ct1. Since the new scan condition Ct1 is Phase = 192, the imaging time can be further shortened than the new scan condition Ct1 by changing Phase to a value smaller than 192. In the first embodiment, the parameter value changing unit 452 changes the Phase value (Phase = 192) defined by the scan condition Ct1 to Phase = 160. The scan condition determination unit 45 determines a scan condition in which the Phase value (Phase = 192) is replaced with Phase = 160 among the new scan conditions Ct1 as another new scan condition Ct2. In this way, another new scan condition Ct2 is determined.

  FIG. 10 is a diagram showing the scan condition C0 and the new scan condition Ct1, and another new scan condition Ct2 replaced by Phase = 160.

  The scan condition Ct2 is the same as the scan condition Ct1 except for the value of Phase. After changing the parameter value in this way, the process proceeds to step S193.

In step S193, the SNR ratio calculating means 46 (see FIG. 2) uses the SNR (= SNR0) of the image obtained using the scan condition C0 and the SNR (= SNR2) of the image obtained using the new scan condition Ct2. To calculate the ratio R02. R02 is calculated from the following equation (2).
R02 = (SNR2 / SNR0) × 100 (2)

  The value of the term (SNR2 / SNR0) in equation (2) can be calculated if the BW and NEX values of the scan conditions C0 and Ct2 are known. Therefore, the ratio R02 can be determined by using equation (2). Here, the ratio R02 = 89% (see FIG. 9). Therefore, it can be seen that when the subject 11 is scanned under another new scanning condition Ct2, the SNR is improved by 7% as compared with the case where scanning is performed under the new scanning condition Ct1. After calculating the SNR ratio R02, the process proceeds to step S194.

  In step S194, the shooting time calculation unit 47 (see FIG. 2) calculates a shooting time Time required for shooting using the new scan condition Ct2. The imaging time Time of the new scan condition Ct2 is 2 minutes 24 seconds (see FIG. 9). Therefore, it can be seen that by changing from Phase = 192 to Phase = 160, the photographing time can be further reduced than the scanning condition Ct1. After the photographing time Time is determined, the process proceeds to step S195.

  In step S195, the changed scan parameter determination unit 451 determines whether or not to change the parameter value of any scan parameter with respect to the scan parameter of the new scan condition Ct2. As shown in FIG. 10, in the scan condition Ct2, the parameter value of Phase is changed with respect to the scan condition Ct1. Therefore, the parameter values “NEX” and “Phase” defined in the column A2 are changed. Therefore, the changed scan parameter determination unit 451 determines that the parameter value is not further changed, and ends the program.

  Therefore, when the item “I want to shorten the photographing time” is selected, two scanning conditions Ct1 and Ct2 shown in FIG. 10 are determined as scanning conditions that can shorten the photographing time. It can be seen that the two scanning conditions Ct1 and Ct2 have a lower SNR than the scanning condition C0, but can sufficiently shorten the imaging time.

  Next, a case where the item “I want to increase SNR” is selected in step S17 (see FIG. 3) will be described.

(B) When “I want to increase SNR” is selected In the description when “I want to increase SNR” is selected, the difference from the case where “I want to shorten the shooting time” is selected is mainly described. To do.

  If the item “I want to increase SNR” is selected in step S17, the process proceeds to step S191 (see FIG. 7).

  In step S191, the changed scan parameter determination unit 451 (see FIG. 2) refers to the table (see FIG. 8) stored in the changed scan parameter storage unit 431, and sets a plurality of scan parameters included in the scan condition C0 in FIG. The scan parameter whose parameter value is changed is determined from among them.

  As shown in FIG. 8, for the item “I want to increase SNR”, two columns B1 and B2 are provided in the column of changed scan parameters. In the columns B1 and B2, “NEX” and “NEX + Phase” are respectively described as in the columns A1 and A2. Therefore, when the item “I want to increase SNR” is selected, the flow of FIG. 7 is executed, so that the new scan condition Cs1 in which only the parameter value of “NEX” is changed, “NEX”, and “Phase”. Another new scanning condition Cs2 in which the parameter value is changed is determined (see FIG. 11).

  FIG. 11 is a diagram showing new scan conditions Cs1 and Cs2 that are determined when “I want to increase SNR” is selected.

  In each of the scan conditions Cs1 and Cs2, the value of NEX and the value of Phase are set so that the SNR is larger than that of the scan condition C0. In the scan condition Cs1, NEX is changed to 4 with respect to the scan condition C0. On the other hand, in the scan condition Cs2, the Phase is changed to 160 with respect to the scan condition Cs1. The SNR ratios of the scan conditions Cs1 and Cs2 are 115% and 126%, respectively, and it can be seen that the SNR is improved over the scan condition C0.

  Next, the case where the item “I want to increase spatial resolution” is selected in step S17 (see FIG. 3) will be described.

(C) When “I want to increase the spatial resolution” is selected In the explanation when “I want to increase the spatial resolution” is selected, the difference from the case where “I want to shorten the shooting time” is mainly selected. Explained.

  If the item “I want to increase spatial resolution” is selected in step S17, the process proceeds to step S191 (see FIG. 7).

  In step S191, the changed scan parameter determination unit 451 (see FIG. 2) refers to the table (see FIG. 8) stored in the changed scan parameter storage unit 431, and sets a plurality of scan parameters included in the scan condition C0 in FIG. The scan parameter whose parameter value is changed is determined from among them.

  As shown in FIG. 8, two columns C1 and C2 are provided in the column of the changed scan parameter for the item “I want to increase the spatial resolution”. In column C1, “FOV” is described. “FOV” means that the parameter to be changed is only FOV. In column C2, “FOV + Phase” is described. “FOV + Phase” means that Phase is added to the parameter to be changed, and the parameter to be changed is FOV and Phase. Of the columns C1 and C2, the changed scan parameter determination unit 451 first determines “FOV” as the scan parameter to be changed according to the contents described in the column C1. Thereafter, the process proceeds to step S192.

  In step S192, the parameter value changing unit 452 (see FIG. 2) changes the FOV parameter value so that the spatial resolution is improved as compared with the scan condition C0 in FIG. In the scan condition C0 in FIG. 4, since FOV = 24, the spatial resolution can be improved by changing the FOV to a value smaller than 24. However, in the first embodiment, the FOV can take only an integer value. Therefore, the parameter value of the FOV that can improve the spatial resolution as compared with the scan condition C0 in FIG. 4 is an integer value smaller than 24. Therefore, when the parameter value changing unit 452 selects an integer value smaller than 24, it is possible to obtain a scan condition in which the spatial resolution is improved compared to the scan condition C0 in FIG. In the first embodiment, the parameter value changing unit 452 changes the FOV to 23. Thereby, the scan condition determining means 45 determines the scan condition in which the FOV value (FOV = 24) is replaced with FOV = 23 in the scan condition C0 of FIG. 4 as a new scan condition. In this way, new scan conditions are determined.

  FIG. 12 is a diagram in which the scan condition C0 of FIG. 4 and the new scan condition Cr1 replaced with FOV = 23 are arranged side by side.

  The new scan condition Cr1 is the same as the scan condition C0 except for the value of FOV. After changing the parameter value in this way, the process proceeds to step S193.

In step S193, the SNR ratio calculating means 46 (see FIG. 2) uses the SNR (= SNR0) of the image obtained using the scan condition C0 and the SNR (= SNR3) of the image obtained using the new scan condition Cr1. The ratio R03 is calculated. R03 is calculated from the following equation (3).
R03 = (SNR3 / SNR0) × 100 (3)

  The value of the term (SNR3 / SNR0) in equation (3) can be calculated if the BW and NEX values of the scan conditions C0 and Cr1 are known. Therefore, the ratio R03 can be calculated by using the equation (3). Here, the ratio R03 = 92% (see FIG. 12). Therefore, it can be seen that when the subject 11 is scanned under the new scan condition Cr1, the SNR is 8% lower than when scanned under the scan condition C0. After calculating the SNR ratio R03, the process proceeds to step S194.

  In step S194, the shooting time calculation unit 47 (see FIG. 2) calculates a shooting time Time required for shooting using the new scan condition Cr1. The imaging time Time of the new scan condition Cr1 is 4 minutes 21 seconds (see FIG. 12). After calculating the photographing time Time, the process proceeds to step S195.

  In step S195, the changed scan parameter determination unit 451 determines whether or not to change the parameter value of any scan parameter with respect to the scan parameter of the new scan condition Cr1. Referring to FIG. 8, when the item “I want to increase spatial resolution” is selected, column C2 (see FIG. 8) stipulates that “Phase” be added to the parameter to be changed. However, only the parameter value “FOV” is changed in the new scan condition Cr1. Therefore, the changed scan parameter determination unit 451 determines to change the parameter value of Phase, and the process returns to step S192.

  In step S192, the parameter value changing unit 452 (see FIG. 2) changes the parameter value of “Phase” with respect to the new scan condition Cr1. In this case, the parameter value changing unit 452 changes the parameter value of “Phase” so that the spatial resolution is improved as compared with the new scan condition Cr1. Since the new scan condition Cr1 is Phase = 192, the spatial resolution can be further improved than the new scan condition Cr1 by changing the Phase to a value larger than 192. In the first embodiment, the parameter value changing unit 452 changes the Phase value (Phase = 192) defined by the new scan condition Cr1 to Phase = 224. The scan condition determination unit 45 determines a scan condition in which the Phase value (Phase = 192) is replaced with Phase = 224 in the new scan condition Cr1 as another new scan condition Cr2. In this way, another new scan condition Cr2 is determined.

  FIG. 13 is a diagram showing the scan condition C0 and the new scan condition Cr1, and another new scan condition Cr2 replaced by Phase = 224.

  The scan condition Cr2 is the same as the scan condition Cr1 except for the value of Phase. After changing the parameter value in this way, the process proceeds to step S193.

In step S193, the SNR ratio calculating means 46 (see FIG. 2) calculates the SNR (= SNR0) of the image obtained using the scan condition C0 and the SNR (= SNR4) of the image obtained using the scan condition Cr2. The ratio R04 is calculated. R04 is calculated from the following equation (4).
R04 = (SNR4 / SNR0) × 100 (4)

  The value of the term (SNR4 / SNR0) in equation (4) can be calculated if the BW and NEX values of the scan conditions C0 and Cr2 are known. Therefore, the ratio R04 can be calculated by using the equation (4). Here, the ratio R04 = 98% (see FIG. 13). After calculating the SNR ratio R04, the process proceeds to step S194.

  In step S194, the shooting time calculation unit 47 (see FIG. 2) calculates the shooting time Time required for shooting using the scan condition Cr2. The imaging time Time of the scan condition Cr2 is 4 minutes 21 seconds (see FIG. 13). After calculating the photographing time Time, the process proceeds to step S195.

  In step S195, the changed scan parameter determination unit 451 determines whether or not to change the parameter value of any scan parameter with respect to the scan parameter of the scan condition Cr2. As shown in FIG. 13, in the scan condition Cr2, the parameter value of Phase is changed with respect to the scan condition Cr1. Therefore, the parameter values “FOV” and “Phase” defined in the column C2 are changed. Therefore, the changed scan parameter determination unit 451 determines that the parameter value is not further changed, and ends the program.

  As shown in FIG. 13, since the scan condition Cr1 has a smaller FOV than the scan condition C0, the spatial resolution can be improved. In addition, since the scan condition Cr2 has a larger Phase than the scan condition Cr1, the spatial resolution can be further improved.

  As described above, the scan condition determining unit 45 (see FIG. 2) determines a new scan condition in step S19 according to the flow shown in FIG. In step S19, after determining new scanning conditions, the process proceeds to step S20 (see FIG. 3).

  In step S20, the monitor 31 displays the scan condition display control unit 423 (see FIG. 2) so that the scan conditions shown in FIG. 10, FIG. 11, or FIG. 13 are displayed according to the item selected in step S17. To control. When the item “I want to shorten the shooting time” is selected in step S17, the scan conditions C0, Ct1, and Ct2 in FIG. 10 are displayed. When the item “I want to increase SNR” is selected, the scan conditions C0, Cs1, and Cs2 of FIG. 11 are displayed. When the item “I want to increase spatial resolution” is selected, the scan conditions C0, Cr1, and Cr2 in FIG. 13 are displayed. The following describes how the scan conditions C0, Ct1, and Ct2 of FIG. 10 are displayed on the monitor 31 when “I want to shorten the shooting time” is selected in step S17.

  FIG. 14 is a diagram showing an example of the display screen 310 of the monitor 31 that displays the scan conditions C0, Ct1, and Ct2 of FIG.

  On the display screen 310, scan conditions C0, Ct1, and Ct2 shown in FIG. 10 are displayed. Under the scan conditions C0, Ct1, and Ct2, an SNR ratio and an imaging time Time are also displayed. Also, selection buttons 317 and 318 and a cancel button 319 are displayed on the left side of the scan conditions C0, Ct1, and Ct2.

  After the display screen 310 as shown in FIG. 14 is displayed, the process proceeds to step S21.

  The operator 29 examines new scanning conditions Ct1 and Ct2 while looking at the display screen 310, and if there is a scanning condition to be tried, clicks the selection button 317 or 318 on the display screen 310. When the selection button 317 is clicked, shooting is performed according to the scanning condition Ct1, and when the selection button 318 is clicked, shooting is performed according to the scanning condition Ct2. If the selection button 317 or 318 is not clicked, the process proceeds to step S22. If the operator 29 does not want to try both scanning conditions Ct1 and Ct2, the operator 29 clicks a cancel button 319. When the cancel button 319 is clicked, the program ends. If the cancel button 319 is not clicked, the process returns from step S22 to step S21. Therefore, the loop of steps S21 and S22 is repeatedly executed until the selection buttons 317 and 318 or the cancel button 319 is clicked. In step S21, for example, when the operator 29 clicks the selection button 317, the scanning condition selection unit 48 (see FIG. 2) determines that the scanning condition Ct1 has been selected, and the MR device control unit 21 of the control device 20 determines. Then, an instruction to execute the scan according to the scan condition Ct1 is sent, and the process proceeds to step S23.

  In step S23, the scan is executed according to the new scan condition Ct1. When the scan is executed, data of the head 11 a is collected from the subject 11 and reconstructed by the image reconstruction unit 22. The reconstructed image is displayed on the monitor 31, and the flow ends.

  In steps S20 to S23, the case where “I want to shorten the shooting time” is selected is described. However, even when “I want to increase SNR” or “I want to increase spatial resolution” is selected, the same applies. Can be explained.

  In the first embodiment, the operator 29 realizes the contents of the item selected by the operator 29 only by selecting one of the plurality of items displayed in the area 314 of the screen 310 in FIG. New scanning conditions are determined. Therefore, the scan condition can be easily determined.

(2) Second Embodiment In the description of the second embodiment, only differences from the first embodiment will be described.

  FIG. 15 is a diagram illustrating functional blocks of the controller device main body 34 in the second embodiment.

  In the second embodiment, a display determination unit 49 is provided in addition to the scan condition setting unit 41 to the scan condition selection unit 48 provided in the first embodiment. The display determination unit 49 determines whether or not to display a new scan condition on the monitor 31.

  FIG. 16 is a diagram showing how the scan conditions C0, Ct1, and Ct2 of FIG. 10 are displayed on the monitor 31 when “I want to shorten the shooting time” is selected in step S17. .

  In the second embodiment, unlike the first embodiment, the new scan condition Ct2 is displayed on the display screen 310, but the new scan condition Cr1 is not displayed. In the second embodiment, the display determination unit 49 determines not to display a scan condition with an SNR ratio of 85% or less. Accordingly, it is possible to prevent the display screen 310 from displaying a scan condition having an SNR that is too low, and it is possible to display only a scan condition that can obtain an image with a certain level of image quality. In the second embodiment, the reference for displaying the scan condition is the SNR ratio of 85%, but the reference value of the SNR ratio may be another value. In the second embodiment, the SNR ratio is used as a reference for displaying the scan condition. However, an imaging time can be used instead of the SNR ratio.

  In the first and second embodiments, items displayed on the screen (see FIG. 6) are “(1) I want to shorten the shooting time”, “(2) I want to increase the SNR”, and “(3 3) “I want to increase spatial resolution”, but other items (for example, items related to contrast) may be provided.

  In the first and second embodiments, an example of the table stored in the changed scan parameter storage unit 431 is shown in FIG. 8, but the changed scan parameter is not necessarily the parameter shown in FIG. However, if necessary, a parameter different from the parameter shown in FIG. 8 may be used as the changed scan parameter. For example, when the item “I want to increase SNR” is selected, in the above embodiment, “Phase” is set as a scan parameter to be changed, but instead of “Phase” (or in addition to “Phase”) And “Freq” may be set to the scan parameter to be changed.

  In the first and second embodiments, the operator 29 selects one item from the above three items, and the scanning condition that satisfies the selected item is determined. However, it is also possible for the operator 29 to select two or more items and to determine a new scanning condition that satisfies the two or more selected items.

  Furthermore, although the MRI system has been described in the first and second embodiments, a new scan condition is determined by the operator 29 selecting an arbitrary item for the CT (Computed Tomography) system. It is possible to do so.

It is a block diagram of MRI system 1 of one embodiment of the present invention. FIG. 4 is a diagram showing functional blocks of the operating device main body 34. It is an example of the flowchart of the MRI system 1 in 1st Embodiment. 2 is an example of scan conditions for a subject 11; It is an example of the display screen 310 of the monitor 31 which displays a reconstructed image. It is a figure which shows an example of the display screen of the monitor 31 which displays a some item. It is a figure which shows an example of the flow of the scanning condition determination performed by step S19. 6 is a diagram illustrating an example of a table stored in a changed scan parameter storage unit 431. FIG. FIG. 5 is a diagram showing the scan condition C0 of FIG. 4 and a new scan condition Ct1 replaced with NEX = 2. It is the figure which showed scan condition C0 and new scan condition Ct1, and another new scan condition Ct2 replaced with Phase = 160 side by side. It is a figure which shows new scanning conditions Cs1 and Cs2 determined when "I want to raise SNR" is selected. FIG. 5 is a diagram showing the scan condition C0 of FIG. 4 and a new scan condition Cr1 replaced with FOV = 23 side by side. It is the figure which showed scan condition C0 and new scan condition Cr1, and new scan condition Cr2 replaced by Phase = 224 side by side. It is a figure which shows an example of the display screen 310 of the monitor 31 which displays the scanning conditions C0, Cr1, and Cr2 of FIG. It is a figure which shows the functional block of the operating device main body 34 in 2nd Embodiment. FIG. 13 is a diagram showing how the scan conditions C0, Cr1, and Cr2 of FIG. 11 are displayed on the monitor 31 when “I want to increase spatial resolution” is selected in step S17.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 MRI system 10 MRI apparatus 11 Subject 11a Head 12 Reception coil 20 Control apparatus 21 MR apparatus control means 22 Image reconstruction means 29 Operator 30 Operation apparatus 31 Monitor 32 Keyboard 33 Mouse 34 Operation apparatus main body 41 Scan condition setting means 42 Display control means 43 Storage means 44 Item selection means 45 Scan condition determination means 46 SNR ratio calculation means 47 Shooting time calculation means 48 Scan condition selection means 49 Display determination means 421 Item display control part 422 Image display control part 423 Scan condition display control part 431 Change scan parameter storage unit 432 Scan condition storage unit 451 Change scan parameter determination unit 452 Parameter value change unit

Claims (11)

A scanning condition determination device for determining scanning conditions when scanning a subject,
A scan condition determining means for determining a new scan condition by changing a parameter value of any one of the plurality of scan parameters of the scan condition;
SNR ratio calculating means for calculating a ratio between the SNR of the image obtained using the scan condition and the SNR of the image obtained using the new scan condition;
Display determination means for determining whether or not to display the new scan condition on the display means according to the ratio value calculated by the SNR ratio calculation means;
A scan condition determining apparatus.   The scanning condition determining apparatus according to claim 1, wherein the display unit displays an item defining characteristics of an image that the operator desires to change.   The scan condition determining apparatus according to claim 2, wherein the characteristic of the image is image quality.   The scan condition determining apparatus according to claim 3, wherein the image quality is SNR or spatial resolution.   The scan condition determining apparatus according to claim 2, wherein the display unit displays an item that defines a reduction in imaging time. In accordance with the operation of the operator, it has an item selection means for selecting an item displayed on the display means,
The scanning condition determining means includes
The scan parameter whose parameter value is changed is determined from the plurality of scan parameters according to the item selected by the item selection means, and the parameter value of the determined scan parameter is changed. The scan condition determining apparatus according to any one of the above.   The scan condition determining apparatus according to claim 1, wherein the display unit displays the new scan condition.   The scan condition determining apparatus according to claim 1, wherein the display unit displays an image of the subject.   A medical system comprising the scan condition determining device according to any one of claims 1 to 8.   The medical system according to claim 9, wherein the medical system is an MRI system or a CT system. A scan condition determination method for determining a scan condition when scanning a subject,
A scan condition determining step for determining a new scan condition by changing a parameter value of any one of the plurality of scan parameters of the scan condition;
An SNR ratio calculating step of calculating a ratio between the SNR of the image obtained using the scan condition and the SNR of the image obtained using the new scan condition;
A display determination step for determining whether or not to display the new scanning condition on a display unit according to the ratio value calculated in the SNR ratio calculation step;
A method for determining scan conditions.

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