Plane detection method and system for SPECT image

Abstract

The invention relates to a plane detection method and system for an SPECT image. The method comprises the following steps: subtracting a corresponding scattering image from an original SPECT image to obtain a corrected image; according to the shape of the motif, averagely dividing a plurality of regions of interest with the same size in a motif range in the center of the image; carrying out multiple times of random sampling point acquisition on each region of interest; determining that the sampling point is valid under the condition that the sampling point meets a preset condition; taking the effective sampling point as a circle center, counting and summing pixel mean values in the ROI range of each random sampling, and obtaining an analysis value of the region of interest; any two of the analysis values of the plurality of regions of interest are taken to calculate a difference ratio; and under the condition that all the difference ratios are smaller than the preset value, determining that the radioactive source is in a uniform horizontal state. The method has the beneficial effect that the plane sensitivity and the penetrability detection efficiency of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical image processing, and in particular to a plane detection method and system for SPECT images. Background Art

[0002] SPECT (Single Photon Emission Computed Tomography) equipment plays a key role in medical diagnosis, and its accuracy directly affects the diagnosis and subsequent treatment plan. Inaccurate imaging may lead to wrong diagnosis, so quality control testing is important to ensure the performance and imaging reliability of the equipment. System plane sensitivity is an important indicator for performance testing.

[0003] System plane sensitivity is the ratio of the activity of the collimated technology detected on a certain acquisition plane to the activity of a specific plane source parallel to the plane. In this test, the prerequisite is to ensure that the radiation source used for detection is a uniform horizontal plane. If the radiation source used for detection is uneven or non-horizontal, it will lead to errors in the analysis results, inaccurate analysis, and even no results will be produced. Summary of the invention

[0004] Technical issues to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a planar detection method and system for SPECT images, which solves the technical problem of how to improve the planar sensitivity and penetration detection efficiency of the system.

[0006] Technical Solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, the present invention provides a planar detection method for a SPECT image, comprising:

[0009] Subtract the SPECT original image from the corresponding scattering image to obtain the corrected image;

[0010] According to the shape of the phantom, multiple regions of interest of equal size are evenly divided within the phantom range at the center of the image;

[0011] Multiple random sampling points were collected for each area of ​​interest;

[0012] The sampling point is determined to be valid if the sampling point meets the preset conditions;

[0013] Taking the effective sampling point as the center of the circle, the mean value of pixels within the ROI range of each random sampling is counted and summed to obtain the analysis value of the region of interest;

[0014] Calculate the difference ratio of any two of the analysis values ​​in multiple regions of interest;

[0015] When all difference ratios are smaller than a preset value, it is determined that the radiation source is in a uniform horizontal state.

[0016] Optionally, according to the shape of the phantom, a plurality of regions of interest of equal size are evenly divided within the phantom range at the center of the image, including:

[0017] According to the circular phantom with a diameter of R, the effective radioactive uptake area with a diameter of R / 2 in the center of the image is evenly divided into multiple regions of interest of equal size.

[0018] Optionally, the preset condition is pointDis+r≤R / 2, where pointDis is the distance from the sampling point to the center of the image, and r is the radius of the region of interest.

[0019] Optionally, r<R / 4.

[0020] Optionally, the distance from the sampling point to the image center is calculated according to the following formula:

[0021] pointDis=(x-Rows / 2) 2 +(y-Columns / 2) 2 , where (Rows / 2, Columns / 2)

[0022] is the image center coordinate, (x, y) is the sampling point coordinate.

[0023] Optionally, the preset value is ±10%.

[0024] In a second aspect, the present invention provides a planar detection system for SPECT images, comprising:

[0025] A correction module, which subtracts the SPECT original image from the corresponding scattering image to obtain a corrected image;

[0026] A sampling module, which divides the phantom range at the center of the image into multiple regions of interest of equal size according to the shape of the phantom;

[0027] The acquisition module collects multiple random sampling points for each area of ​​interest;

[0028] A first determination module determines that the sampling point is valid if the sampling point meets a preset condition;

[0029] The statistical module takes the effective sampling point as the center of the circle, counts the mean value of pixels within the ROI range of each random sampling and sums them up to obtain the analysis value of the region of interest;

[0030] A calculation module, randomly selecting two of the analysis values ​​of a plurality of regions of interest and calculating a difference ratio;

[0031] The second determination module determines that the radiation source is in a uniform horizontal state when all difference ratios are less than a preset value.

[0032] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed, the planar detection method of a SPECT image as described in any one of the first aspects above is implemented.

[0033] In a fourth aspect, the present invention provides a storage device including a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, the planar detection method of a SPECT image described in any one of the first aspects above is implemented.

[0034] Beneficial Effects

[0035] The beneficial effects of the present invention are as follows: a plane detection method of a SPECT image of the present invention simply collects SPECT images through a SPECT device, introduces random sampling according to the image processing results, analyzes and compares the statistical results of the sampled area of ​​interest, and judges whether the radiation source is completely horizontal according to the comparison results. This method can not only improve the accuracy of the horizontal result judgment, but also reduce the contact time between the operator and the radiation source. The present invention has been integrated into the performance detection software, and after use and inspection, it can shorten the performance detection time and improve efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of a planar detection method for a SPECT image provided by an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of ROI (Region of Interest) analysis results when the detection result provided by an embodiment of the present invention is a non-uniform radiation source or a non-horizontal plane;

[0038] Figure 3 A schematic diagram of ROI analysis results when the detection result provided by the embodiment of the present invention is a uniform radiation source horizontal plane. DETAILED DESCRIPTION

[0039] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0040] SPECT equipment is a radionuclide imaging device, and the performance of the equipment must comply with the national GB / T18989-2013 standard. In the performance test project, the system plane sensitivity and penetration test is an important test and one of the important indicators to measure the performance of the equipment. When conducting the test, before the image is collected, the radioactive source needs to be scattered in the water body in the flat plastic plate. After ensuring that the radioactive source is evenly distributed in the water body, the image collection is started. The acquisition requires intermittent adjustment of the equipment for multiple acquisitions, which takes a long time. If the radioactive source is not evenly diffused in the water body or there are high concentration points, the test results will be inaccurate and the test will fail, thereby reducing the test efficiency. In addition, the radioactive source weakens over time. If the test results cannot be obtained in a timely and accurate manner, it will also cause waste.

[0041] The present invention uses SPECT digital medical images and statistical analysis and comparison methods to assist in the uniformity analysis of the radiation source in the phantom for performance testing, thereby improving the system's planar sensitivity and the efficiency of penetration testing.

[0042] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0043] First, refer to Figure 1 This embodiment provides a planar detection method for a SPECT image, comprising:

[0044] S1, subtract the SPECT original image from the corresponding scattering image to obtain a corrected image.

[0045] S2, according to the shape of the phantom, the phantom range in the center of the image is evenly divided into multiple regions of interest of equal size.

[0046] S3, randomly collect sampling points for each region of interest multiple times.

[0047] S4, determining that the sampling point is valid when the sampling point meets the preset conditions.

[0048] S5, taking the effective sampling point as the center of the circle, counting and summing the pixel means within the ROI range of each random sampling to obtain the analysis value of the region of interest.

[0049] S6, randomly select two of the analysis values ​​of the multiple regions of interest and calculate the difference ratio.

[0050] S7, when all difference ratios are less than a preset value, determining that the radiation source is in a uniform horizontal state.

[0051] The present embodiment provides a planar detection method for SPECT images, which obtains SPECT images and corresponding scattering images, and calculates the corrected images by image subtraction. According to the shape of the phantom, multiple regions of interest are selected within the range of the phantom displayed in the image, and statistical analysis is performed on the regions of interest. All regions of interest are compared and analyzed, and the range difference of the statistical value analyzed according to the empirical value is within the preset value, indicating that the radiation source is evenly distributed in the phantom, and the performance detection analysis can continue. If it is not satisfied, it is necessary to wait until the radiation source is evenly diffused, and then collect the image analysis again. After the analysis results meet the above conditions, the subsequent performance analysis can be continued.

[0052] Optionally, based on the shape of the phantom, a plurality of regions of interest are randomly sampled within the phantom range at the center of the image, including:

[0053] According to the circular phantom with a diameter of R, the effective radioactive uptake area with a diameter of R / 2 in the center of the image is evenly divided into multiple regions of interest of equal size.

[0054] Since the phantom for performance testing needs to be a standard phantom, the phantom should be a circular culture dish with a fixed diameter R. Therefore, the radioactive source of the liquid is scattered in the phantom. The effective radioactive uptake area of ​​the image collected by the SPECT device is also circular. Therefore, the random sampling position is set to be centered on the image, and the circle with a radius of R / 2 is the effective radioactive uptake area.

[0055] Optionally, the preset condition is pointDis+r≤R / 2, where pointDis is the distance from the sampling point to the center of the image, and r is the radius of the region of interest.

[0056] Optionally, r<R / 4.

[0057] Optionally, the distance from the sampling point to the image center is calculated according to the following formula:

[0058] pointDis=(x-Rows / 2) 2 +(y-Columns / 2) 2 , where (Rows / 2, Columns / 2)

[0059] is the image center coordinate, (x, y) is the sampling point coordinate.

[0060] Optionally, the preset value is ±10%.

[0061] Compare the analysis values ​​of each area of ​​interest. When the comparison results are within ±10%, it is considered that the radiation source in the phantom is in a uniform horizontal state. Subsequent performance tests can be continued. If the difference is greater than ±10%, the test needs to be repeated after a period of time.

[0062] In the actual SPECT performance analysis operation process, the radioactive source needs to be injected into the phantom first, and the radioactive source needs to be placed horizontally. After the radioactive source is evenly dispersed in the phantom, the system performance analysis can be performed. In this process, it is mostly placed manually, and the position of the phantom is adjusted to observe whether the radioactive source in the phantom is evenly placed horizontally. In order to ensure that the radioactive source is even in the phantom, it is usually observed and judged by naked eyes after a period of rest. In this process, the operator will have close contact with the radioactive source many times and be exposed to the radiation environment.

[0063] In the present invention, SPECT images are simply collected by SPECT equipment, random sampling is introduced according to the image processing results, and the statistical results of the sampled area of ​​interest are analyzed and compared, and whether the radiation source is completely horizontal is judged according to the comparison results. This method can not only improve the accuracy of the horizontal result judgment. It also reduces the contact time between the operator and the radiation source. The present invention has been integrated into the performance detection software, and after use and inspection, it can shorten the performance detection time and improve efficiency.

[0064] A planar detection method for SPECT images of the present application is further described below with reference to a specific embodiment.

[0065] Read the DICOM file generated by the SPECT device into the memory, parse and load the file according to the DICOM3.0 standard. Obtain the parameter values ​​required for subsequent calculations from the metadata field in the DICOM header information, including the number of rows (0x0028, x0010), the number of columns (0028, 0011), and the pixel point space size PixelSpacing (0028, 0030). The original image pixel data set is recorded as PixelData0.

[0066] Since the image of the scattering medium will cause the spatial resolution to decrease and affect the image quality when the SPECT device is collecting, it is necessary to exclude the influence of this factor on the results in the subsequent calculations, perform image correction, and read and parse the DICOM file of the scattering image corresponding to the above SPECT image into the memory. The resolution of the scattering image is the same as that of the original image, and the scattering image pixel data set is also recorded in Rows×Columns as PixelData1.

[0067] The image pixel data of the image correction result is PixelDataResult, which is obtained as follows: PixelDataResult[i] = PixelData0[i] - PixelData1[i], where 0≤i <Rows×Columns。

[0068] A circular phantom with a diameter of R was used for detection, and the effective radioactive uptake area of ​​the collected image was the circular area in the center of the image.

[0069] According to the spatial relationship of the image pixel arrangement, the image is regarded as a two-dimensional array, and the center position coordinates can be recorded as (m / 2, n / 2). Then a circle with this center as the center and a radius of R / 2 is established as the effective radioactive uptake area. In this area, image sampling and analysis are performed.

[0070] The number of pixels in the X direction is recorded as xSize=R / (2×PixelSpacing[x]).

[0071] The number of pixels in the Y direction is ySize=R / (2×PixelSpacing[y]).

[0072] Then the image is divided into 4 parts along the X and Y directions from the center point. The range is:

[0073] Area 1: Rows / 2-xSize <x<Rows / 2,Columns / 2-ySize<y<Columns / 2,

[0074] Area 2: Rows / 2 <x<Rows / 2+xSize,Columns / 2-ySize<y<Columns / 2,

[0075] Area 3: Rows / 2 <x<row / 2+xSize,Columns / 2<y<Columns / 2+ySize,

[0076] Area 4: Rows / 2-xSize <x<row / 2,Columns / 2<y<Columns / 2+ySize。

[0077] A circular ROI with a diameter less than R / 4 is used as the statistical calculation unit. In this example, the ROI radius is 5 mm.

[0078] Take region 1 as an example: within the region, randomly sample a pixel point, record the position as Pos(x, y), and calculate the distance from the point to the center of the image:

[0079] pointDis=(x-Rows / 2) 2 +(y-Columns / 2)2 ;

[0080] When pointDis+5mm≤R / 2, calculate the average value ROIstdDev of the pixels in the ROI area with Pos as the center and a radius of 5mm.

[0081] When pointDis+5mm>R / 2, reselect the sampling point.

[0082] Assume that the number of random sampling points is n, and calculate the final mean STDDEV by taking the average value of the n ROIs:

[0083] STDDEV=∑ROIstdDev(i) / n, where i=0, 1,...n

[0084] After the above steps, the analysis value STDDEV of area 1 is obtained.

[0085] Traverse the four divided areas and repeat the above steps for each area, and finally obtain four sets of analysis values ​​STDDEV(i), i=0, 1, 2, 3.

[0086] Statistical analysis Take any two values ​​in STDDEV(i) and calculate the difference ratio:

[0087] Difference ratio = (STDDEV(i)-STDDEV(j)) / STDDEV(i);

[0088] Where i=0, 1, 2, 3, j=0, 1, 2, 3 and i≠j.

[0089] According to empirical values, when the ratio of all analyzed differences is less than ±10%, the radiation source is approximately uniform and the plane on which it is located can appear to be horizontal; otherwise, the radiation source is non-uniform.

[0090] Through the above steps, the final uniformity analysis of the radiation source is given, which can provide the prerequisite guarantee for the performance test of the subsequent system.

[0091] like Figure 2 and Figure 3 Shown are schematic diagrams of ROI analysis results when the radiation source is non-uniform or non-horizontal, and when the radiation source is uniform and horizontal.

[0092] In the second aspect, the present embodiment provides a plane detection system for SPECT images, including: a correction module, which subtracts the SPECT original image and the corresponding scattering image to obtain a corrected image; a sampling module, which divides the phantom range at the center of the image into multiple regions of interest of equal size according to the shape of the phantom; a collection module, which randomly collects sampling points for each region of interest multiple times; a first determination module, which determines that the sampling point is valid when the sampling point meets the preset conditions; a statistical module, which takes the valid sampling point as the center of the circle, counts the pixel mean within the ROI range of each random sampling and sums them to obtain the analysis value of the region of interest; a calculation module, which randomly selects two of the analysis values ​​of multiple regions of interest to calculate the difference ratio; a second determination module, which determines that the radiation source is in a uniform horizontal state when all the difference ratios are less than the preset value. According to the plane detection system for SPECT images provided by this embodiment, since it is used to implement the steps of a plane detection method for SPECT images provided by the first aspect of the present invention, the plane detection system for SPECT images has all the technical effects of the plane detection method for SPECT images, which will not be repeated here.

[0093] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed, the planar detection method of a SPECT image as described in any one of the first aspects above is implemented.

[0094] In a fourth aspect, an embodiment of the present invention provides a storage device, including a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, the planar detection method of a SPECT image described in any one of the first aspects above is implemented.

[0095] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

[0097] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A planar detection method for SPECT images, characterized in that: include: Subtract the SPECT original image from the corresponding scattering image to obtain the corrected image; According to the shape of the phantom, multiple regions of interest of equal size are evenly divided within the phantom range at the center of the image; Multiple random sampling points were collected for each area of ​​interest; The sampling point is determined to be valid if the sampling point meets the preset conditions; Taking the effective sampling point as the center of the circle, the mean value of pixels within the ROI range of each random sampling is counted and summed to obtain the analysis value of the region of interest; Calculate the difference ratio of any two of the analysis values ​​in multiple regions of interest; When all difference ratios are smaller than a preset value, it is determined that the radiation source is in a uniform horizontal state.

2. A planar detection method for SPECT images according to claim 1, characterized in that: According to the shape of the phantom, multiple regions of interest of equal size are evenly divided within the phantom range in the center of the image, including: According to the circular phantom with a diameter of R, the effective radioactive uptake area with a diameter of R / 2 in the center of the image is evenly divided into multiple regions of interest of equal size.

3. A planar detection method for SPECT images according to claim 2, characterized in that: The preset condition is pointDis+r≤R / 2, where pointDis is the distance from the sampling point to the center of the image, and r is the radius of the region of interest.

4. A planar detection method for SPECT images according to claim 3, characterized in that: r＜R / 4。 5. A planar detection method for SPECT images according to claim 4, characterized in that: The distance from the sampling point to the image center is calculated according to the following formula: pointDis = (x - Rows / 2) 2 + (y - Columns / 2) 2 , where (Rows / 2, Columns / 2) is the image center coordinate, (x, y) is the sampling point coordinate.

6. A planar detection method for SPECT images according to claim 5, characterized in that: The preset value is ±10%.

7. A planar detection system for SPECT images, characterized in that: include: A correction module, which subtracts the SPECT original image from the corresponding scattering image to obtain a corrected image; A sampling module, which divides the phantom range at the center of the image into multiple regions of interest of equal size according to the shape of the phantom; The acquisition module collects multiple random sampling points for each area of ​​interest; A first determination module determines that the sampling point is valid if the sampling point meets a preset condition; The statistical module takes the effective sampling point as the center of the circle, counts the mean value of pixels within the ROI range of each random sampling and sums them up to obtain the analysis value of the region of interest; A calculation module, randomly selecting two of the analysis values ​​of a plurality of regions of interest and calculating a difference ratio; The second determination module determines that the radiation source is in a uniform horizontal state when all difference ratios are less than a preset value.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the planar detection method of a SPECT image as claimed in any one of claims 1 to 6 is implemented.

9. A storage device comprising a storage medium and a processor, wherein the storage medium stores a computer program, wherein: When the processor executes the computer program, the planar detection method of a SPECT image as described in any one of claims 1 to 6 is implemented.

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