CN101766494A - Method for reusing operation parameters of high-intensity focused ultrasound equipment - Google Patents

Abstract

The invention discloses a method for reusing operation parameters of high-intensity focused ultrasound equipment. The method comprises the following steps: before a patient is moved, scanning the patient with magnetic resonance imaging equipment to obtain an image before moving; after the patient is moved, positioning a sickbed which bears the patient and scanning the patient with the magnetic resonance imaging equipment again according to scanning parameters used by the image before moving to obtain an image after moving; judging whether a position difference before and after the patient is moved is acceptable according to the image before moving and the image after moving; if the position difference is acceptable to the high-intensity focused ultrasound equipment, proceeding the operation by adopting the operation parameters before the patient is moved; and otherwise, performing the step of positioning the sickbed and the subsequent steps again. By adopting the method, after the patient is moved, the high-intensity focused ultrasound equipment can still adopt the operation parameters before the patient is moved.

Description

The method that the operating parameter of high intensity focused ultrasound equipment can be used once again

Technical field

The present invention relates to high intensity focused ultrasound (HIFU) technical field of nuclear magnetic resonance (MRI) monitoring, the method that particularly a kind of operating parameter that makes high intensity focused ultrasound equipment can use once again.

Background technology

In high intensity focused ultrasound (the MRI guided HIFU) equipment of nuclear magnetic resonance monitoring, usually scan by MR imaging apparatus, obtain the image of patient's region of interest, high intensity focused ultrasound equipment image that MR imaging apparatus scanning is obtained is as the reference image then, operate, thereby utilize ultrasound wave that patient is treated.

Generally speaking, the operating time of high intensity focused ultrasound equipment is longer, can reach several hours usually.In the so long time, be difficult to allow patient keep transfixion.After patient is moved, because variation has taken place for patient's position, makes the operating environment of high intensity focused ultrasound equipment that variation also correspondingly take place, and can not adopt the operating parameter of patient before being moved.The new operating parameter that this just need redefine high intensity focused ultrasound equipment has not only increased the useless operation of high intensity focused ultrasound equipment, but also has increased patient's waiting time.

Therefore, expectation can still can be used the operating parameter of patient before being moved by high intensity focused ultrasound equipment after patient is moved.

Summary of the invention

In view of this, the present invention proposes the method that a kind of operating parameter that makes high intensity focused ultrasound equipment can use once again, with so that high intensity focused ultrasound equipment still can adopt the operating parameter of patient before being moved after patient is moved.

Therefore, the invention provides the method that a kind of operating parameter that makes high intensity focused ultrasound equipment can use once again, this method comprises:

Before patient is moved, use patient with magnetic resonance imaging to scan, image before obtaining moving;

After patient was moved, location carrying patient's sick bed according to the used sweep parameter of image before described the moving, used described patient with magnetic resonance imaging to scan once more, obtains moving the back image;

According to described preceding image and the mobile back image of moving, judge that patient moves front-back direction difference and whether can accept, if the operating parameter continuation that then described high intensity focused ultrasound equipment adopts patient to move is before operated; Otherwise, carry out the step and the subsequent step thereof of locating described sick bed once more.

Preferably, judge and patient move front-back direction difference whether acceptable step comprises:

Cut apart image before described move and move area-of-interest in the image of back, calculates image before described the moving and move after the degree of association of area-of-interest described in the image, judge the described degree of association whether greater than or more than or equal to a threshold value.

This method may further include: strengthen the described edge that moves preceding image and move area-of-interest described in the image of back, so that described cutting apart.

Preferably, use Canny operator to detect the edge of described area-of-interest.

This method may further include: the voxel size before making described mobile back image and moving in the image is identical.

Following formula is adopted in the calculating of the described degree of association:

$f\left(t\right)=\frac{{\mathrm{\Σ}}_{p\∈O}[I_f\left(p\right)-{\stackrel{\‾}{I}}_f][I_t(p+t)-{\stackrel{\‾}{I}}_t]}{{\left\{{\mathrm{\Σ}}_{p\∈O}{[I_f\left(p\right)-{\stackrel{\‾}{I}}_f]}^2{\mathrm{\Σ}}_{p\∈O}{[I_t(p+t)-{\stackrel{\‾}{I}}_t]}^2\right\}}^{1/2}}$

Wherein ${\stackrel{\‾}{I}}_f=\frac{1}{n}\underset{p\∈O}{\mathrm{\Σ}}{I}_f\left(p\right)$ ， ${\stackrel{\‾}{I}}_t=\frac{1}{n}\underset{p\∈O}{\mathrm{\Σ}}{I}_t\left(p\right);$

Wherein, f (t) is an image and the degree of association that moves area-of-interest in the image of back, I before moving _fBe the area-of-interest in the image before moving, I _tBe the area-of-interest that moves in the image of back, p is the position of moving area-of-interest in the preceding image, and t is that area-of-interest is with respect to the translation of area-of-interest in the image before moving in the image of mobile back, and n is counting of being considered among the O of overlapping region, With

Be in the O of overlapping region, to calculate to move area-of-interest and the arithmetic average that moves the pixel value of area-of-interest in the image of back in the preceding image.

Preferably, image before described the moving being carried out down-sampling with mobile back image handles.

This method further comprises: move under the acceptable situation of front-back direction difference patient, use described mobile back image to be reference picture.

Preferably, operating parameter before the employing patient moves continues before the operation, calculate the described offset vector that moves between preceding image and the mobile back image, calculate the side-play amount of the focal track of high intensity focused ultrasound equipment according to described offset vector, and be applied to the operating parameter of patient before moving.

From such scheme as can be seen, since the present invention before patient uses before and after being moved MR imaging apparatus scanning to obtain moving respectively image and move after image, judge that according to image before moving and mobile back image patient moves front-back direction difference and whether can accept then, if then high intensity focused ultrasound equipment continues to adopt the operating parameter that used before patient is moved, thereby make the operating parameter of high intensity focused ultrasound equipment before patient is moved to use once again, avoid determining once more required operation and the time of operating parameter, improved the service efficiency of the high intensity focused ultrasound equipment of nuclear magnetic resonance monitoring.

Description of drawings

Fig. 1 is the flow chart according to the embodiment of the invention.

The specific embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in more detail by the following examples.

Core concept of the present invention is, utilize the MRI image of patient before and after moving to judge whether patient's front-back direction difference that is moved can be accepted, if, then high intensity focused ultrasound equipment continue to adopt the operating parameter of patient before being moved, otherwise locatees sick bed, scanogram once more and judge.

Fig. 1 is the flow chart according to the embodiment of the invention.As shown in Figure 1, the method for the embodiment of the invention may further comprise the steps:

Step 110, high intensity focused ultrasound equipment use a cover operating parameter that the patient on the sick bed is operated.

Step 120, when patient will be moved, for example patient needed activity or other reasons and move on one's sick bed or leave sick bed once.Before patient is moved, utilize patient with magnetic resonance imaging to scan, image before obtaining moving.

The embodiment of the invention preferably scans the position that patient is operated by high intensity focused ultrasound equipment, thereby obtains the image of patient body certain volume.Preferably, present embodiment scanning obtains 3D rendering.

Step 130, patient is moved, for example patient leaves sick bed, perhaps patient move on one's sick bed, rotation etc.

Step 140 after patient is moved, reapposes patient on one's sick bed, and will carry the magnet of patient's sick bed immigration MR imaging apparatus, utilizes the positioner location sick bed of MR imaging apparatus self.

Step 150 utilizes patient with magnetic resonance imaging to scan, and (that is, the scanning in the step 120) sweep parameter is identical, obtains moving the back image for the scanning before used sweep parameter and patient are moved.

Owing to adopt identical sweep parameter, the position of being scanned before position that current scanning is scanned and patient are moved is roughly the same or approaching.

Step 160, MR imaging apparatus are cut apart mobile preceding image and are moved the back image, extract area-of-interest (ROI) respectively.The area-of-interest here for example is the object that patient's organ, tissue etc., particularly high intensity focused ultrasound equipment will be operated.

In the process of segmented sense region-of-interest, mainly cut apart by the edge of area-of-interest, can adopt several different methods to detect the edge of area-of-interest, preferably, adopt Tuscany (Canny) operator to detect the edge of area-of-interest in the present embodiment.

Before extracting area-of-interest, can also strengthen the edge of area-of-interest, so that segmented sense region-of-interest better.

In addition, owing to the sampled point that moves preceding image and mobile back image that MR imaging apparatus scanning obtains is more, such image is handled to cause huge amount of calculation.In order to reduce the amount of calculation of MR imaging apparatus, present embodiment can be further to image before moving with move the back image and carry out down-sampling and handle, for example with the 256*256 down-sampling to 64*64.

Step 170 according to image before moving with move area-of-interest in the image of back, judges that patient moves front-back direction difference and whether can accept, if can accept, and then execution in step 180 and subsequent step thereof, otherwise execution in step 140 and subsequent step thereof.

Present embodiment can adopt several different methods to judge that patient moves front-back direction difference and whether can accept.

Here introduce a kind of method of utilizing the degree of association of area-of-interest.Image and move the degree of association of area-of-interest in the image of back before calculate moving, judge the described degree of association whether greater than or more than or equal to a threshold value that sets in advance.When the degree of association greater than or more than or equal to threshold value, the position of the area-of-interest before the area-of-interest that moves in the image of back being described and moving in the image is more approaching, patient is moved front-back direction difference for accepting; Otherwise the position of the area-of-interest before the area-of-interest that moves in the image of back being described and moving in the image differs bigger, and patient's front-back direction difference that is moved is unacceptable.

The embodiment of the invention gives a kind of method of calculating the above-mentioned degree of association, and this method adopts following formula:

$f\left(t\right)=\frac{{\mathrm{\Σ}}_{p\∈O}[I_f\left(p\right)-{\stackrel{\‾}{I}}_f][I_t(p+t)-{\stackrel{\‾}{I}}_t]}{{\left\{{\mathrm{\Σ}}_{p\∈O}{[I_f\left(p\right)-{\stackrel{\‾}{I}}_f]}^2{\mathrm{\Σ}}_{p\∈O}{[I_t(p+t)-{\stackrel{\‾}{I}}_t]}^2\right\}}^{1/2}}$

Wherein, ${\stackrel{\‾}{I}}_f=\frac{1}{n}\underset{p\∈O}{\mathrm{\Σ}}{I}_f\left(p\right),$ ${\stackrel{\‾}{I}}_t=\frac{1}{n}\underset{p\∈O}{\mathrm{\Σ}}{I}_t\left(p\right).$

In the equation above, f (t) is an image and the degree of association that moves area-of-interest in the image of back, I before moving _fBe the area-of-interest in the image before moving, I _tBe the area-of-interest that moves in the image of back, p is the position of moving area-of-interest in the preceding image, and t is that area-of-interest is with respect to the translation of area-of-interest in the image before moving in the image of mobile back, and n is counting of being considered among the O of overlapping region,

With

Be in the O of overlapping region, to calculate to move area-of-interest and the arithmetic average that moves the pixel value of area-of-interest in the image of back in the preceding image.

In addition, in the image of scanning gained, the size of voxel (voxel) might be different before patient moves and after moving.In this flow process, before the compute associations degree, can further include one make move before the step that equates with voxel size in the mobile image afterwards of voxel in the image.

Step 180, high intensity focused ultrasound equipment carries out follow-up operation to move the back image as the reference image.

Step 190, high intensity focused ultrasound equipment adopt the operating parameter before patient is moved to proceed operation, and do not need to redefine operating parameter.

Before and after patient is moved, some take place and move in high intensity focused ultrasound equipment operated position possibly, move under the acceptable situation of front-back direction difference patient so, can further calculate the described offset vector that moves between preceding image and the mobile back image, calculate the side-play amount of the focus of high intensity focused ultrasound equipment then according to this offset vector, and this side-play amount is applied to the operating parameter (especially locus this parameter and with locus relevant parameter) of patient before moving, high intensity focused ultrasound equipment adopts these operating parameters to proceed subsequent operation.

The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. method that the operating parameter that makes high intensity focused ultrasound equipment can use once again, this method comprises:

Before patient is moved, use patient with magnetic resonance imaging to scan, image before obtaining moving;

After patient was moved, location carrying patient's sick bed according to the used sweep parameter of image before described the moving, used described patient with magnetic resonance imaging to scan once more, obtains moving the back image;

According to described preceding image and the mobile back image of moving, judge that patient moves front-back direction difference and whether can accept, if the operating parameter continuation that then described high intensity focused ultrasound equipment adopts patient to move is before operated; Otherwise, carry out the step and the subsequent step thereof of locating described sick bed once more.

2. method according to claim 1 is characterized in that, judges patient to move front-back direction difference whether acceptable step comprises:

Cut apart image before described move and move area-of-interest in the image of back, calculates image before described the moving and move after the degree of association of area-of-interest described in the image, judge the described degree of association whether greater than or more than or equal to a threshold value.

3. method according to claim 2 is characterized in that, this method further comprises: strengthen the described edge that moves preceding image and move area-of-interest described in the image of back, so that described cutting apart.

4. method according to claim 3 is characterized in that, uses Canny operator to detect the edge of described area-of-interest.

5. method according to claim 1 and 2 is characterized in that, this method further comprises: the voxel size before making described mobile back image and moving in the image is identical.

6. method according to claim 2 is characterized in that, following formula is adopted in the calculating of the described degree of association:

$f\left(t\right)=\frac{{\mathrm{\Σ}}_{p\∈O}[I_f\left(p\right)-{\stackrel{\‾}{I}}_f][I_t(p+t)-{\stackrel{\‾}{I}}_t]}{{\left\{{\mathrm{\Σ}}_{p\∈O}{[I_f\left(p\right)-{\stackrel{\‾}{I}}_f]}^2{\mathrm{\Σ}}_{p\∈O}{[I_t(p+t)-{\stackrel{\‾}{I}}_t]}^2\right\}}^{1/2}}$

Wherein

Wherein, f (t) is an image and the degree of association that moves area-of-interest in the image of back, I before moving _fBe the area-of-interest in the image before moving, I _tBe the area-of-interest that moves in the image of back, p is the position of moving area-of-interest in the preceding image, and t is that area-of-interest is with respect to the translation of area-of-interest in the image before moving in the image of mobile back, and n is counting of being considered among the O of overlapping region,

With

Be in the O of overlapping region, to calculate to move area-of-interest and the arithmetic average that moves the pixel value of area-of-interest in the image of back in the preceding image.

7. method according to claim 1 and 2 is characterized in that, image before described the moving is carried out down-sampling with mobile back image handle.

8. method according to claim 1 is characterized in that, this method further comprises: move under the acceptable situation of front-back direction difference patient, use described mobile back image to be reference picture.

9. method according to claim 1, it is characterized in that, operating parameter before the employing patient moves continues before the operation, calculate the described offset vector that moves between preceding image and the mobile back image, calculate the side-play amount of the focal track of high intensity focused ultrasound equipment according to described offset vector, and be applied to the operating parameter of patient before moving.

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