CN109171790B - CT scanning data processing method and device and CT machine - Google Patents
CT scanning data processing method and device and CT machine Download PDFInfo
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Abstract
The application discloses a processing method and device of CT scanning data and a CT machine. Obtaining the eccentricity degree of the mold body according to the centroid position and the central channel position of all channels of the current layer of the current scanning angle corresponding to the receiving values of the detector; when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree; and carrying out filtering and denoising processing on the received value in the channel range to obtain a denoised received value. The method and the device use the eccentricity degree of the die body as a guide, carry out filtering and denoising processing on the receiving value in the channel range, and effectively solve the problem of inconsistent CT image noise caused by eccentricity.
Description
Technical Field
The present application relates to the technical field of medical equipment, and in particular, to a method and an apparatus for processing CT scan data, and a CT machine.
Background
Computed Tomography (CT) is widely used in medical and industrial fields. The CT machine is provided with a shape filter, and in the scanning process of the CT machine, the shape filter can reduce the radiation dose received by a scanned object on one hand and can adjust the intensity distribution of the radiation before the radiation passes through the scanned object on the other hand. If the shape filter is not arranged, the intensity of the rays before passing through the scanned object is the same, but the human body is generally thick in the middle and thin at two sides, so that the transmitted dose of parts at two sides of the human body received by the detector of the CT machine is larger, and the noise is smaller; the dosage of the middle part of the human body is small, the noise is large, and further, the noise in the whole image is inconsistent, and the imaging quality is influenced. Therefore, the presence of the shape filter can better accommodate noise inconsistencies in the image.
Ideally, when CT scanning is performed, the scanned part of the human body is located at the center of the scanning field of view, and the noise in the CT image is relatively consistent. However, in practical operation, it is often difficult to avoid the situation that the scanning part of the human body deviates from the center of the scanning field of view, and the noise generated by eccentricity causes poor consistency of the noise in the CT image. Due to the existence of the shape filter of the CT machine, under the condition of the same scanning dosage, if the scanning part deviates from the center of the scanning visual field by a longer distance, the phenomenon of inconsistent noise in the CT image is more obvious, and even the medical diagnosis of the CT image is interfered when the phenomenon of inconsistent noise is serious.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a method and an apparatus for processing CT scan data, and a CT machine, so as to solve the problem of inconsistent CT image noise caused by decentering.
The application provides the following technical scheme:
in a first aspect of the present application, a method for processing CT scan data is provided, where the method includes:
obtaining the eccentricity degree of the mold body according to the centroid position and the central channel position of all channels of the current layer of the current scanning angle corresponding to the receiving values of the detector;
when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree;
and carrying out filtering and denoising treatment on the received value in the channel range to obtain a denoised received value.
Optionally, denoising the received value in the channel range specifically includes:
and denoising the received value of which the received value in the channel range is smaller than a preset processing threshold value.
Optionally, obtaining a channel range to be denoised according to the eccentricity degree specifically includes:
obtaining the number of channels which do not need denoising processing according to the eccentricity degree and the preset number of channels, wherein the preset number of channels is related to a shape filter of the CT machine;
obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, wherein the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle.
Optionally, the method for processing CT scan data provided by the present application further includes:
obtaining the smaller value of the maximum receiving value of the right end channel of the first channel interval and the maximum receiving value of the left end channel of the second channel interval;
the denoising processing is performed on the received value in the channel range, and specifically includes:
and denoising the received value with the receiving value smaller than the smaller value in the channel range.
Optionally, the obtaining the maximum receiving value of the right end channel of the first channel interval specifically includes:
obtaining the maximum value of the receiving values of a first preset number of channels adjacent to the right end channel in the first channel interval from a first preset number of channels adjacent to the right end channel in the first channel interval to a second preset number of channels adjacent to the right end channel in the first channel interval as the maximum receiving value of the right end channel;
the obtaining of the maximum receiving value of the left end channel of the second channel interval specifically includes:
and obtaining the maximum value of the receiving values of a third preset number of channels adjacent to the left end channel of the second channel interval from the front side to the rear side as the maximum receiving value of the left end channel.
Optionally, the filtering and denoising processing on the received value in the channel range specifically includes:
and carrying out filtering and denoising treatment on the received value in the channel range by using a bilateral filtering method.
In a second aspect of the present application, there is provided an apparatus for processing CT scan data, the apparatus comprising:
the first acquisition module is used for acquiring the eccentricity degree of the mold body according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle;
the second acquisition module is used for acquiring a channel range needing denoising processing according to the eccentricity when the eccentricity is larger than a preset eccentricity value, and the channel range is in direct proportion to the eccentricity;
and the data processing module is used for carrying out filtering and denoising processing on the receiving value in the channel range to obtain a denoised receiving value.
Optionally, the second obtaining module includes:
the first acquisition submodule is used for acquiring the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels, and the preset number of channels is related to a shape filter of the CT machine;
the second obtaining submodule is used for obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, and the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle.
Optionally, the processing apparatus for CT scan data provided in the present application further includes:
a third obtaining module, configured to obtain a smaller value of a maximum receiving value of a right-end channel of the first channel interval and a maximum receiving value of a left-end channel of the second channel interval;
the data processing module is specifically configured to perform denoising processing on the received value in the channel range that is smaller than the smaller received value.
Optionally, the third obtaining module includes: a third obtaining submodule and a fourth obtaining submodule;
the third obtaining submodule is configured to obtain a maximum value of receiving values of a first preset number of channels adjacent to a right end channel in the first channel interval before to a second preset number of channels adjacent to the right end channel in the first channel interval after, as the maximum receiving value of the right end channel;
the fourth obtaining submodule is configured to obtain a maximum value of receiving values of a third preset number of channels adjacent to the left end channel in the second channel interval before to a fourth preset number of channels adjacent to the left end channel in the second channel interval after, as the maximum receiving value of the left end channel.
Optionally, the data processing module is configured to perform filtering and denoising processing on the received value within the channel range by using a bilateral filtering method.
In a third aspect of the present application, a CT machine is provided, which includes: a detector and a computer;
the computer is used for obtaining the eccentricity degree of the phantom according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle;
when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree;
and carrying out filtering and denoising treatment on the received value in the channel range to obtain a denoised received value.
Compared with the prior art, the method has the advantages that:
the eccentricity degree of the mold body is obtained according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle; when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree; and carrying out filtering and denoising processing on the received value in the channel range to obtain a denoised received value.
According to the method, after the eccentricity degree of a die body is obtained, the eccentricity degrees of all channel receiving values are screened according to the size relation between the eccentricity degree and a preset eccentricity value, only when the eccentricity degree is larger than the preset eccentricity value, the receiving values are subjected to denoising processing, and denoising processing is not needed for the receiving values of which the eccentricity degrees are smaller than the preset eccentricity value. The larger the eccentricity degree is, the worse the image noise consistency is, so that the channel range needing to be subjected to denoising treatment is in direct proportion to the eccentricity degree, namely the larger the eccentricity degree is, the larger the channel range needing to be subjected to denoising treatment is, the channel range needing to be subjected to denoising treatment is determined according to the eccentricity degree, the determined channel range is adapted to the eccentricity degree, and the condition that the channel range subjected to denoising treatment is too large or too small is avoided. Therefore, the processing method of the CT scanning data uses the eccentricity degree of the die body as a guide, carries out filtering and denoising processing on the receiving value in the channel range, and effectively solves the problem of inconsistent CT image noise caused by eccentricity.
Drawings
In order to more clearly illustrate the technical solutions in the present embodiment or the prior art, the drawings needed to be used in the description of the embodiment or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a method for processing CT scan data according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of a CT machine according to the present disclosure;
FIG. 3 is a schematic diagram of all channels of a current layer at a current scanning angle according to the present application;
FIG. 4 is an image reconstructed from non-denoised scan data provided herein;
FIG. 5 is an image reconstructed from scan data processed by the CT scan data processing method provided herein;
FIG. 6 is a flowchart of another CT scan data processing method according to an embodiment of the present disclosure;
fig. 7 is a schematic structural diagram of a device for processing CT scan data according to an embodiment of the present disclosure;
fig. 8 is a schematic structural diagram of a CT machine according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In order to obtain a high-quality CT image, it is necessary to ensure that the scanning part is located at the center of the scanning field of view as far as possible during the scanning and imaging process of the CT machine. However, in actual operation, due to various factors, such as the difference between the actual scanning posture of the human body and the ideal scanning posture, the actual scanning part deviates from the center of the scanning visual field, i.e., the eccentricity is caused. The eccentricity has an influence on the imaging quality of CT scanning, and the phenomenon of inconsistent noise appears in a CT image.
The inventor finds that under the same scanning dose, if the distance of the scanning part deviating from the center of the scanning visual field is increased, the noise in the image is enhanced, and the phenomenon of noise inconsistency in the CT image is more remarkable. Noise not only affects image quality, but also may interfere with medical diagnosis of CT images when severe. Therefore, there is a need to solve the problem of inconsistent noise in CT images caused by the eccentricity of the scanned object.
Based on the above thought, the present application provides a method for processing CT scan data. Firstly, calculating the eccentricity degree of a scanned object; then determining whether the received data of the CT machine needs to be denoised according to the eccentricity degree; when the received data of the CT machine needs to be denoised, a channel range corresponding to the received data needing to be denoised is determined by taking the eccentricity of a scanning object as a basis, then the data in the channel range is denoised, and the denoised data is obtained. The denoised data is used for CT image reconstruction, so that the problem of inconsistent CT image noise caused by the eccentricity of a scanned object can be effectively solved.
The following describes in detail a specific implementation of the CT scan data processing method provided in the present application with reference to fig. 1 to 5.
The first embodiment of the method comprises the following steps:
referring to fig. 1, a flowchart of a method for processing CT scan data according to an embodiment of the present disclosure is shown.
The method for processing CT scan data provided in this embodiment includes:
s101: and obtaining the eccentricity degree of the phantom according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle.
In this embodiment, a phantom is taken as an example of a scanned object for description. The phantom may be a water phantom or a human head phantom, and herein, the type of the phantom to which the processing method of CT scan data provided in this embodiment is applied is not limited.
To facilitate understanding of the scanning angle, slice, and channel concepts of the CT machine, the present steps are described with reference to the CT machine configuration illustrated in fig. 2 and the relative positions of the various components.
Fig. 2 is a schematic structural diagram of a CT machine provided in this embodiment.
As shown in fig. 2, the CT machine includes a support 201 rotatable about a rotation axis 202; the radiation source 203 forms a radiation beam 205 through the aperture 204, the radiation beam 205 may pass through a phantom 206 at a central position of the support 201, and the radiation beam 205 passes through the phantom 206 and impinges on the detector 207. The detector 207 is arranged on the gantry 201 opposite the source 203, and the surface of the detector is completely covered by the radiation beam 205 when the CT machine is in operation. The CT machine scans the phantom 206 device, the source 203, the aperture 204 and the detector 207, around the rotational axis 202, in the direction indicated by arrow 208. The radiation source 203 rotates around the rotation axis 202 by one revolution, and correspondingly, the scanning angle changes continuously during the rotation. The scan angle may be a fixed angle for each position to which the radiation source 203 is rotated.
The detector 207 is divided into a plurality of layers in the Z direction and a plurality of channels in the X direction, whereby the detector 207 is an array-like detection device constituted by a plurality of detection cells. The detection units on the same layer are arranged along the X direction, and the detection units on the same channel are arranged along the Z direction. Taking the detecting unit 209 in fig. 2 as an example, the detecting unit 209 is a detecting unit located at the 7 th layer of the 3 rd channel. The received values of each detection unit are used as scanning data for CT image reconstruction.
The die body eccentricity refers to the difference between the position of the center of a scanning part of the die body and the position of the center of a scanning visual field of a CT machine. The eccentricity d is used for representing the position difference between the center of the scanning part of the phantom and the center of the scanning visual field of the CT machine.
The inventor finds that the receiving values of the detecting units in different layers at the same scanning angle are affected by the eccentricity of the mold body to different degrees, and the receiving values of the detecting units in different layers at different scanning angles are also affected by the eccentricity of the mold body to different degrees, so that the CT scanning data processing method provided by the application needs to calculate the difference between the position of the mass center of the receiving values of the detectors corresponding to all channels of each layer at each scanning angle and the position of the central channel, obtain the eccentricity degree respectively, and perform denoising processing on the scanning data respectively by using each eccentricity degree. The present embodiment is described by taking the current layer of the current scanning angle as an example.
The centroid positions of the receiving values of all channels of the current layer of the current scanning angle corresponding to the detectors correspond to the positions of the centers of the scanning parts of the mold bodies, the positions of the central channels correspond to the positions of the scanning vision centers of the CT machine, the centroid positions of the receiving values of all channels of the current layer of the current scanning angle corresponding to the detectors can be subtracted from the positions of the central channels to obtain a subtraction result dif, and the absolute value of dif is used as the eccentricity degree d of the mold bodies.
The positive and negative criteria of the dif value can be customized, for example, when the center of the scanning part of the die body deviates leftwards relative to the center of the scanning visual field, the corresponding dif is a positive value; when the center of the scanning part of the phantom deviates to the right relative to the center of the scanning visual field, the corresponding dif is a negative value. Similarly, when the center of the scanning part of the die body deviates leftwards relative to the center of the scanning visual field, the corresponding dif is set to be a negative value; when the center of the scanning portion of the phantom deviates rightward from the center of the scanning field of view, the corresponding dif is a positive value.
In order to obtain the eccentricity d of the phantom, this embodiment provides a method for determining the centroid positions of the received values of the detectors corresponding to all channels of the current layer at the current scanning angle. Assuming that the current layer of the current scanning angle has M channels, the receiving value of the s-th channel is corrected by air (s is more than or equal to 1 and less than or equal to M, and s is a positive integer), and the obtained corrected receiving value is q(s). And obtaining the Centroid position Centroid of the detector receiving value corresponding to all channels of the current layer of the current scanning angle according to the following formula:
as a specific example, the current scan angle is 50, the current layer is layer 2, and layer 2 of the detector contains 45 channels. The 23 rd channel of the layer 2 detector is the central channel of all 45 channels, and the channel is located at the position X0 in the X direction. The Centroid position of the detector receiving value corresponding to all channels is Centroid0 according to the formula (1), so that the eccentricity degree of the phantom is d-Centroid 0-x 0.
S102: when the eccentricity degree is larger than the preset eccentricity value, the channel range needing denoising processing is obtained according to the eccentricity degree, and the channel range is in direct proportion to the eccentricity degree.
In addition, when the position difference between the center of the scanning part of the phantom and the center of the scanning visual field is small, the eccentricity degree of the phantom is low, the consistency of the caused image noise is good, and at the moment, the denoising processing of the scanning data is not needed. For this reason, this step divides the eccentricity degree by a preset eccentricity value: when the eccentricity degree d is smaller than the preset eccentricity value, the eccentricity degree of the die body is low, the consistency of the caused image noise is good, and the scanning data does not need to be processed; and when the eccentricity degree d is larger than the preset eccentricity value, the eccentricity degree of the mold body is higher, the consistency of the image noise caused by the higher eccentricity degree is poorer, and the received value needs to be processed.
The larger the eccentricity degree of the die body is, the more remarkable the phenomenon of image noise inconsistency generated by the eccentricity of the die body is.
As an alternative embodiment, when the eccentricity degree d is greater than the preset eccentricity value, obtaining the channel range to be denoised by d may include:
s1021: and obtaining the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels.
Alternatively, equation (2) may be used to calculate half of the number of channels that do not require denoising:
n＝(n0-d)*cof (2)
in the above formula, n is half of the number that does not require denoising processing; n is0Is a predetermined number of channels, n0Regarding the shape filter of the CT machine, if the shape filter of the CT machine is not changed, n is0Is also unchanged; d represents the degree of eccentricity; cof are preset tuning parameters. If n is a value less than 0 as calculated according to equation (2), then n is directly set to 0.
After n is obtained through calculation, the number 2n of channels which do not need to be denoised can be obtained.
S1022: and obtaining a channel range needing denoising processing from the number of channels not needing denoising processing, wherein the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ].
Wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer at the current scanning angle. After the number of channels which do not need denoising processing is obtained at S1021, the step takes a central channel m as a boundary, and channels except the adjacent n channels form a first channel interval [1, m-n ] from the central channel in front of the central channel; after the central channel, channels other than the adjacent N channels form a second channel interval [ m + N, N ] from the central channel. The range of the channel to be denoised is the union of the first channel interval and the second channel interval.
For ease of understanding, this step can be referred to fig. 3, which is a schematic diagram of all channels of the current layer at the current scanning angle. As shown in fig. 3, 1 is a starting channel, N is the number of all channels of the current layer at the current scanning angle, m is a central channel, and N channels not requiring denoising processing are respectively arranged on the left side and the right side of m, that is, there are 2N channels not requiring denoising processing; 301 is a first channel section requiring denoising, and 302 is a second channel section requiring denoising.
S103: and carrying out filtering and denoising processing on the received value in the channel range to obtain a denoised received value.
Through S102, range of channels to be denoised is obtained, and the step may directly perform filtering and denoising processing on the received values corresponding to the channels in range p.
The inventor has found that the smaller the receiving value in the channel, the lower the signal-to-noise ratio, the greater the influence of the phantom eccentricity, and the worse the image noise consistency. It will be appreciated that within the range of channels where denoising is desired, there may be one or more large received values that are less affected by phantom eccentricity. Therefore, the step can also select to carry out filtering and denoising processing on the smaller receiving value in the channel range.
As an optional implementation manner, this step may specifically include:
and denoising the received value with the received value smaller than a preset processing threshold value in the channel range. If the receiving value in the channel range is smaller than the preset processing threshold value, the receiving value is greatly influenced by the eccentricity of the die body, so that the consistency of image noise is deteriorated, and the receiving value is subjected to denoising processing; if the receiving value in the channel range is larger than or equal to the preset processing threshold value, the receiving value is less influenced by the eccentricity of the phantom, denoising is not needed, and the receiving values can be directly used as scanning data for CT image reconstruction.
As another optional implementation manner, in order to determine the received value that needs to be processed, a non-fixed processing threshold may be set in this step, and denoising processing may be performed on the received value that is smaller than the preset processing threshold. The specific setting manner of the processing threshold will be described in detail in the following embodiments.
When the denoising algorithm is used for denoising the received value, as an optional implementation manner, a bilateral filtering method may be adopted to perform filtering denoising processing on the received value within the channel range to be denoised. Of course, other denoising algorithms may be adopted in this step to process the received value within the channel range, and here, the denoising processing mode of the received value is not limited.
The denoised received values can be further used for CT image reconstruction.
Referring to fig. 4 and 5, when the phantom is a water phantom, the processing effect of the CT scan data is contrasted, where fig. 4 is an image reconstructed from scan data without denoising, and fig. 5 is an image reconstructed from scan data processed by the CT scan data processing method provided by the present application. Comparing fig. 4 with the same region 401 in fig. 5 shows that the phenomenon of noise inconsistency in the region 401 in fig. 4 is serious, but the noise shape consistency in the region 401 in fig. 5 is improved through the denoising processing of the received values, and a better image effect is exhibited compared with fig. 4.
The above is a method for processing CT scan data provided in the embodiment of the present application. The method obtains the eccentricity degree of the mold body according to the centroid position and the central channel position of all channels of the current layer of the current scanning angle corresponding to the receiving values of the detector; when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree; and carrying out filtering and denoising processing on the received value in the channel range to obtain a denoised received value.
According to the method, after the eccentricity degree of a die body is obtained, the eccentricity degrees of all channel receiving values are screened according to the size relation between the eccentricity degree and a preset eccentricity value, only when the eccentricity degree is larger than the preset eccentricity value, the receiving values are subjected to denoising processing, and denoising processing is not needed for the receiving values of which the eccentricity degrees are smaller than the preset eccentricity value. The larger the eccentricity degree is, the worse the image noise consistency is, so that the channel range needing to be subjected to denoising treatment is in direct proportion to the eccentricity degree, namely the larger the eccentricity degree is, the larger the channel range needing to be subjected to denoising treatment is, the channel range needing to be subjected to denoising treatment is determined according to the eccentricity degree, the determined channel range is adapted to the eccentricity degree, and the condition that the channel range subjected to denoising treatment is too large or too small is avoided. Therefore, the processing method of the CT scanning data uses the eccentricity degree of the die body as a guide, carries out filtering and denoising processing on the receiving value in the channel range, and effectively solves the problem of inconsistent CT image noise caused by eccentricity.
The second method embodiment:
in the method for processing CT scan data provided in the foregoing embodiment, as the smaller the receiving value in the channel is, the lower the signal-to-noise ratio is, the larger the influence of the phantom eccentricity will be, and the worse the image noise consistency is, therefore, in S103, the filtering and denoising processing may be selected to be performed on the smaller receiving value. However, when the dose of the CT scanning phantom is too large or too small, the receiving value is wholly large or small in the channel range which is obtained by the eccentricity and needs to be denoised, and if the receiving value which needs to be denoised is determined by always adopting a fixed threshold, the determined receiving value is likely to be too small or too much because the set threshold is not applicable, so that the continuity and the smoothness are to be improved after data processing.
For this reason, the inventors have further proposed another CT scan data processing method through research. The method adaptively sets a non-fixed processing threshold according to the received value in the channel range, determines the received value needing denoising according to the processing threshold, can effectively improve the continuity and smoothness of the processed data, and solves the problem of inconsistent image noise. An embodiment of the method for processing CT scan data is described in detail below with reference to fig. 6.
Referring to fig. 6, it is a flowchart of another CT scan data processing method provided in the embodiment of the present application.
The method for processing CT scan data provided in this embodiment includes:
s601: and obtaining the eccentricity degree of the phantom according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle.
S602: and when the eccentricity degree is greater than the preset eccentricity value, obtaining the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels.
S603: and obtaining a channel range needing denoising processing from the number of channels not needing denoising processing, wherein the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ].
In this embodiment, S601 to S603 are the same as S101, S1021, and S1022 in the foregoing embodiment, respectively, and for brevity, detailed description is omitted here, and detailed information can refer to related description in the foregoing embodiment.
The inventor finds that, in the received value near the right channel of the first channel section and the received value near the left channel of the second channel section, selecting the processing threshold to determine the received value to be processed can largely ensure the continuity and smoothness of data processing in the first channel section and the second channel section.
Therefore, in the method for processing CT scan data provided in the embodiment of the present application, the setting manner of the processing threshold value as detailed in S604 and the denoising processing manner of the received value as detailed in S605 are adopted. S604 and S605 specifically follow:
s604: and obtaining the smaller value Thre of the maximum receiving value of the right-end channel of the first channel interval and the maximum receiving value of the left-end channel of the second channel interval.
In practical application, the maximum receiving value LeftMax in the receiving values of the channels in a certain range near the right end channel of the first channel interval and the receiving values of the channels in a certain range near the left end channel of the second channel interval can be obtained from the received values respectively by traversing the receiving values of the channels in a certain range near the right end channel of the first channel interval and the receiving values of the channels in a certain range near the left end channel of the second channel interval, and then the smaller value of the LeftMax and the RightMax is determined through comparison. The present embodiment may use the smaller value Thre as the processing threshold.
In practical application, as an optional implementation manner, S604 may specifically include:
s6041: and obtaining the maximum value of the receiving values of a first preset number channel adjacent to the right end channel in the first channel interval from a first preset number channel adjacent to the right end channel in the first channel interval to a second preset number channel adjacent to the right end channel in the first channel interval as the maximum receiving value of the right end channel.
In this step, the first preset number and the second preset number are commonly used to determine a channel range, in which traversal is required and a corresponding received value is acquired, near a right-end channel of the first channel interval. The first preset number a and the second preset number b may be the same or different. The right channel of the first channel interval, that is, the rightmost channel in the first channel interval, is obtained in S603, and then the right channel of the first channel interval is determined. If the right end channel of the first channel interval is the A-th channel, determining that a first preset number of channels adjacent to the right end channel of the first channel interval from a first preset number of channels adjacent to the right end channel of the first channel interval to a second preset number of channels adjacent to the right end channel of the first channel interval are intervals [ A-a, A + b ].
For ease of understanding, the steps are described by way of example as follows.
For example, if the number N of all channels of the current layer at the current scanning angle is 45, the number m of the central channels is 23, and the number 2N of channels that do not require denoising processing is 12, then S603 obtains the range of channels that do not require denoising processing, including the first channel section [1,17 ]. If the first predetermined number a is the same as the second predetermined number b, and a equals to 4, then this step determines that the interval from the first predetermined number of lanes before the right end lane of the first lane interval to the second predetermined number of lanes after the right end lane of the first lane interval is [13,21 ].
The specific values of a and b are not specifically limited in this embodiment, and those skilled in the art can select the setting according to the model of the CT machine and the requirement for image accuracy.
This step represents, by LeftMax, the maximum value among the reception values of the first preset number of channels a adjacent before the right-end channel a of the first channel section to the second preset number of channels b adjacent after the right-end channel a of the first channel section. If the reception value corresponding to each channel in [ a-a, a + b ] is represented by Q, for example, Q (a-a), Q (a-a +1) … Q (a), Q (a +1) … Q (a + b), etc., the maximum reception value LeftMax of the right-end channel of the first channel section may be represented by LeftMax ═ max [ Q (a-a) … Q (a + b) ].
S6042: and obtaining the maximum value of the receiving values of a third preset number of channels adjacent to the left end channel in the second channel interval from the front side to the rear side as the maximum receiving value of the left end channel.
In this step, the third preset number and the fourth preset number are commonly used to determine a channel range, in which traversal is required near the left-end channel of the second channel interval and a corresponding received value is acquired. The third preset number c and the fourth preset number f may be the same or different. The left end channel of the second channel interval, that is, the leftmost channel in the second channel interval, is obtained in S603, and then the left end channel of the second channel interval can be determined. And if the left end channel of the second channel interval is the B-th channel, determining that a third preset number of channels adjacent to the left end channel of the second channel interval from a third preset number of channels adjacent to the left end channel of the second channel interval to a fourth preset number of channels adjacent to the left end channel of the second channel interval are an interval [ B-c, B + f ].
For ease of understanding, the steps are described by way of example as follows.
For example, if the number N of all channels in the current layer at the current scanning angle is 45, the number m of the central channels is 23, and the number 2N of channels that do not require denoising processing is 12, then S603 obtains a channel range that requires denoising processing from the number of channels that do not require denoising processing, including the second channel section [29,45 ]. If the third preset number c is the same as the fourth preset number f, and c ═ f ═ 4, then this step determines that the third preset number of channels before the left end channel of the second channel interval is adjacent to the fourth preset number of channels after the right end channel of the first channel interval is the interval [25,33 ].
The specific values of c and f are not specifically limited in this embodiment, and those skilled in the art can select the setting according to the model of the CT machine and the requirement for image accuracy.
In this step, RightMax represents the maximum value of the received values of the third preset number of channels c adjacent to the left end channel B of the second channel section before to the fourth preset number of channels f adjacent to the left end channel B of the second channel section after. If the reception value corresponding to each channel in [ B-c, B + f ] is represented by Q, for example, Q (B-c), Q (B-c +1) … Q (B), Q (B +1) … Q (B + f), etc., the left-end channel maximum reception value RightMax of the second channel section may be represented as RightMax ═ max [ Q (B-c) … Q (B + f) ].
It should be noted that, in this embodiment, the order of obtaining the right-end channel maximum received value LeftMax of the first channel interval and the left-end channel maximum received value RightMax of the second channel interval is not limited. That is, S6041 may be executed prior to or later than S6042, or may be executed simultaneously with S6042.
S6043: and comparing the maximum receiving value of the right-end channel of the first channel interval with the maximum receiving value of the left-end channel of the second channel interval, and determining the smaller value Thre.
In this step, the smaller of the right-end channel maximum reception value LeftMax of the first channel section and the left-end channel maximum reception value RightMax of the second channel section is denoted by thread, which is min (LeftMax, RightMax). Thre is a processing threshold value selected in this embodiment, and the processing threshold value is used to determine a received value that needs to be denoised. Because the received value to be processed is a received value smaller than the thread, when the thread takes the larger value of LeftMax and RightMax, the larger value is likely to be larger than all the received values, so that all the received values need to be denoised, and the significance of denoising after filtering the received values is lost.
S605: and denoising the receiving value with the receiving value smaller than the smaller value in the channel range to obtain a denoised receiving value.
In practical application, the receiving value Q smaller than Thre in the channel range determined in S603 and requiring denoising may be obtained by using the bilateral filtering method shown in formula (3)0And (6) denoising. Q0' is Q0And processing the data by a bilateral filtering method.
Wherein the position set Ω is according to Q0Determined by corresponding channel position, omega is the received value Q containing the to-be-processed value0Corresponding channel position, and Q0A set of positions of adjacent channel positions around the corresponding channel position; (i, j) locations for each channel within Ω; q (i, j) is a receiving value corresponding to a channel with the position (i, j) in omega; w (i, j) is a processing coefficient corresponding to the reception value Q (i, j).
In the above formula, the denominator on the right side of the equal sign represents the summation of the processing coefficients W (i, j) corresponding to the received values Q (i, j) of each channel in the position set Ω; the numerator represents that the received values Q (i, j) of each channel in the position set omega are summed after being integrated with the corresponding processing coefficient W (i, j).
In equation (3), the processing coefficient W (i, j) can be expressed by equation (4):
W(i,j)＝w1(i,j)*w2(i,j) (4)
in formula (4), the processing coefficients W (i, j) are determined by W1(i, j) and W2(i, j), W1(i, j) represents the processing amplitude, W2(i, j) represents the weight, and W1(i, j) and W2(i, j) are gaussian functions. w1(i, j) and w2(i, j) can be expressed by equation (5) and equation (6), respectively:
in equation (5), the value of l depends on the value Rio, which is inversely proportional to Rio, where Rio is Q0/Thre，Q0Is an acceptance value less than Thre, so 0. ltoreq. Rio < 1. From the expression of the value Rio, Q is expressed0The closer to Thre, the closer to 1 Rio, the smaller the value of l, thus making the Gaussian function w1(i, j) in equation (5) more energy-intensive and the smaller the calculated processing amplitude w1(i, j) value; and Q0The greater the difference from Thre, the closer Rio is to 0, the greater the value of l, thus making the Gaussian function w1(i, j) in equation (5) more energy dispersive, the greater the calculated process amplitude w1(i, j). It can be understood that the value Q is received0The smaller the magnitude the more it needs to be processed.
In equation (6), σ is a constant. As can be seen from equation (6), by receiving the value Q0The weight w2(i, j) is determined as the difference in the received values of the neighboring channels around its corresponding channel position. Receiving value Q needing denoising processing0The smaller the difference in the reception values from the adjacent channels around its corresponding channel position, the larger the weight w2(i, j); and the received value Q is processed by de-noising if necessary0The larger the difference in received values from the adjacent channels around its corresponding channel position, the smaller the weight w2(i, j). It can be understood that the value Q is received0The closer the received values of the neighboring channels around its corresponding channel position, the greater the weight.
Substituting equations (5) and (6) into equation (4) yields the following expression for the processing coefficient W (i, j):
as can be seen from equation (7), the values of the processing coefficients W (i, j) and l and (Q (i, j) -Q0)2Is correlated. The closer Q0 is to Thre, the smaller the value of l is, the smaller the processing coefficient W (i, j) is; receiving value Q0The larger the difference in the reception value Q (i, j) from the adjacent channel around its corresponding channel position is, (Q (i, j) -Q0)2The larger the value of (b), the smaller the processing coefficient W (i, j).
The bilateral filtering method shown in formula (3) is adopted in the step, and the airspace information of a channel where the receiving value to be processed is located and the magnitude of the receiving value to be processed are considered at the same time. In one aspect, the post-processing scan data varies relatively smoothly in the received values of the channels adjacent around the channel in which it is located, as compared to the received values before processing. On the other hand, if the received values before processing are used for forming important edges in the reconstructed image, the de-noising processing method of the received values takes the numerical value of the received values into consideration, so that the edges in the image can still be effectively maintained after the image reconstruction is performed on the processed scan data.
The above is a method for processing CT scan data provided in the embodiment of the present application. The method obtains the eccentricity degree of the mold body according to the centroid position and the central channel position of all channels of the current layer of the current scanning angle corresponding to the receiving values of the detector; when the eccentricity degree is larger than a preset eccentricity value, obtaining the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels; and obtaining the channel range needing denoising treatment from the number of channels not needing denoising treatment, wherein the channel range comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]. Obtaining the smaller value Thre of the maximum receiving value of the right-end channel of the first channel interval and the maximum receiving value of the left-end channel of the second channel interval; and then carrying out denoising treatment on the receiving value with the receiving value smaller than the smaller value in the channel range to obtain a denoised receiving value.
In the method, because the numerical values of the receiving values near the end parts of the first channel section and the second channel section have influence on the continuity and smoothness of data processing, the smaller value Thre is selected from the maximum receiving value of the right-end channel of the first channel section and the maximum receiving value of the left-end channel of the second channel section and is used as a processing threshold value to determine the receiving value needing to be processed. Therefore, after the received value in the channel range is subjected to denoising processing, the continuity and the smoothness of the data are improved, and therefore the phenomenon of inconsistent noise in the original image is further improved by utilizing the processed data to reconstruct the CT image.
Based on the processing method of CT scan data in the foregoing embodiment, the embodiment of the present application further provides a processing device of CT scan data. The following describes the processing device of CT scan data provided in the present application in detail with reference to fig. 7.
The embodiment of the device is as follows:
referring to fig. 7, this figure is a schematic structural diagram of a device for processing CT scan data according to an embodiment of the present application.
The processing device for CT scan data provided by the embodiment includes:
the first obtaining module 71 is configured to obtain an eccentricity degree of the mold body according to the centroid position and the center channel position of the detector receiving values corresponding to all channels of the current layer at the current scanning angle;
a second obtaining module 72, configured to, when the eccentricity degree is greater than a preset eccentricity value, obtain, from the eccentricity degree, a channel range that needs to be denoised, where the channel range is directly proportional to the eccentricity degree;
and the data processing module 73 is configured to perform filtering and denoising processing on the received value in the channel range to obtain a denoised received value.
The above is a processing device of CT scan data provided in the embodiment of the present application. After the device obtains the eccentricity degree of a die body, the eccentricity degrees of all channel receiving values are screened according to the size relation between the eccentricity degree and the preset eccentricity value, the receiving values are denoised only when the eccentricity degree is larger than the preset eccentricity value, and the denoising treatment is not needed for the receiving values of which the eccentricity degrees are smaller than the preset eccentricity value. The larger the eccentricity degree is, the worse the image noise consistency is, so that the channel range needing to be subjected to denoising treatment is in direct proportion to the eccentricity degree, namely the larger the eccentricity degree is, the larger the channel range needing to be subjected to denoising treatment is, the channel range needing to be subjected to denoising treatment is determined according to the eccentricity degree, the determined channel range is adapted to the eccentricity degree, and the condition that the channel range subjected to denoising treatment is too large or too small is avoided. Therefore, the processing device of the CT scanning data uses the eccentricity degree of the mold body as a guide, carries out filtering and denoising processing on the receiving value in the channel range, and effectively solves the problem of inconsistent CT image noise caused by eccentricity.
In some possible implementations of the present application, in the above apparatus, the second obtaining module 72 includes:
the first acquisition submodule is used for acquiring the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels, and the preset number of channels is related to a shape filter of the CT machine;
the second obtaining submodule is used for obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, and the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle.
In some possible implementations of the present application, the apparatus further includes:
a third obtaining module, configured to obtain a smaller value of a maximum receiving value of a right-end channel of the first channel interval and a maximum receiving value of a left-end channel of the second channel interval;
the data processing module is specifically configured to perform denoising processing on the received value in the channel range that is smaller than the smaller received value.
In some possible implementations of the present application, the third obtaining module includes: a third obtaining submodule and a fourth obtaining submodule;
the third obtaining submodule is configured to obtain a maximum value of receiving values of a first preset number of channels adjacent to a right end channel in the first channel interval before to a second preset number of channels adjacent to the right end channel in the first channel interval after, as the maximum receiving value of the right end channel;
the fourth obtaining submodule is configured to obtain a maximum value of receiving values of a third preset number of channels adjacent to the left end channel in the second channel interval before to a fourth preset number of channels adjacent to the left end channel in the second channel interval after, as the maximum receiving value of the left end channel.
In some possible implementations of the present application, the data processing module 73 is configured to perform filtering and denoising processing on the received values in the channel range by using a denoising algorithm.
As an alternative embodiment, the data processing module 73 may be configured to perform filtering and denoising processing on the received values in the channel range by using a bilateral filtering method.
In the device, because the numerical values of the receiving values near the end parts of the first channel section and the second channel section have influence on the continuity and smoothness of data processing, the smaller value Thre is selected from the maximum receiving value of the right-end channel of the first channel section and the maximum receiving value of the left-end channel of the second channel section and is used as a processing threshold value to determine the receiving value needing to be processed. Therefore, after the received value in the channel range is subjected to denoising processing, the continuity and the smoothness of the data are improved, and therefore the phenomenon of inconsistent noise in the original image is further improved by utilizing the processed data to reconstruct the CT image.
Based on the processing method of the CT scan data in the foregoing embodiment, the embodiment of the present application further provides a CT machine. The CT machine provided by the present application is described in detail below with reference to fig. 8.
The embodiment of the equipment comprises:
referring to fig. 8, the drawing is a schematic structural view of a CT machine provided in the embodiment of the present application.
The CT machine 81 provided in the present embodiment includes: a detector 811 and a computer 812;
the computer 812 is used for obtaining the eccentricity degree of the phantom according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle;
when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree;
carrying out filtering and denoising processing on the received value in the channel range to obtain a denoised received value
The above is the CT machine provided in the embodiment of the present application. After the computer of the CT machine obtains the eccentricity degree of the mold body, the eccentricity degrees of all channel receiving values are screened according to the size relation between the eccentricity degree and the preset eccentricity value, only when the eccentricity degree is larger than the preset eccentricity value, the receiving values are denoised, and the denoising processing is not needed for the receiving values of which the eccentricity degrees are smaller than the preset eccentricity value. The larger the eccentricity degree is, the worse the image noise consistency is, so that the channel range needing to be subjected to denoising treatment is in direct proportion to the eccentricity degree, namely the larger the eccentricity degree is, the larger the channel range needing to be subjected to denoising treatment is, the channel range needing to be subjected to denoising treatment is determined according to the eccentricity degree, the determined channel range is adapted to the eccentricity degree, and the condition that the channel range subjected to denoising treatment is too large or too small is avoided. Therefore, the CT machine provided by the application uses the eccentricity degree of the die body as a guide, carries out filtering and denoising processing on the receiving value in the channel range, and effectively solves the problem of inconsistent CT image noise caused by eccentricity.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
The foregoing is merely a preferred embodiment of the present application and is not intended to limit the present application in any way. Although the present application has been described with reference to the preferred embodiments, it is not intended to limit the present application. Those skilled in the art can now make numerous possible variations and modifications to the disclosed embodiments, or modify equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the claimed embodiments. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application still fall within the protection scope of the technical solution of the present application without departing from the content of the technical solution of the present application.
Claims (10)
1. A method for processing CT scan data, comprising:
obtaining the eccentricity degree of the mold body according to the centroid position and the central channel position of all channels of the current layer of the current scanning angle corresponding to the receiving values of the detector;
when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree; the method specifically comprises the following steps: obtaining the number of channels which do not need denoising processing according to the eccentricity degree and the preset number of channels, wherein the preset number of channels is related to a shape filter of the CT machine; obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, wherein the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle;
and carrying out filtering and denoising treatment on the received value in the channel range to obtain a denoised received value.
2. The method for processing CT scan data according to claim 1, wherein the de-noising processing is performed on the received values in the channel range, specifically:
and denoising the received value of which the received value in the channel range is smaller than a preset processing threshold value.
3. The method for processing CT scan data according to claim 1, further comprising:
obtaining the smaller value of the maximum receiving value of the right end channel of the first channel interval and the maximum receiving value of the left end channel of the second channel interval;
the denoising processing is performed on the received value in the channel range, and specifically includes:
and denoising the received value with the receiving value smaller than the smaller value in the channel range.
4. The method for processing CT scan data according to claim 3, wherein the obtaining the maximum receiving value of the right channel of the first channel interval specifically includes:
obtaining the maximum value of the receiving values of a first preset number of channels adjacent to the right end channel in the first channel interval from a first preset number of channels adjacent to the right end channel in the first channel interval to a second preset number of channels adjacent to the right end channel in the first channel interval as the maximum receiving value of the right end channel;
the obtaining of the maximum receiving value of the left end channel of the second channel interval specifically includes:
and obtaining the maximum value of the receiving values of a third preset number of channels adjacent to the left end channel of the second channel interval from the front side to the rear side as the maximum receiving value of the left end channel.
5. The method for processing CT scan data according to any of claims 1 to 4, wherein the filtering and de-noising processing is performed on the received values in the channel range, specifically:
and carrying out filtering and denoising treatment on the received value in the channel range by using a bilateral filtering method.
6. An apparatus for processing CT scan data, comprising:
the first acquisition module is used for acquiring the eccentricity degree of the mold body according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle;
the second acquisition module is used for acquiring a channel range needing denoising processing according to the eccentricity when the eccentricity is larger than a preset eccentricity value, and the channel range is in direct proportion to the eccentricity; the method specifically comprises the following steps: the first acquisition submodule is used for acquiring the number of channels which do not need denoising treatment according to the eccentricity degree and the preset number of channels, and the preset number of channels is related to a shape filter of the CT machine; the second obtaining submodule is used for obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, and the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle;
and the data processing module is used for carrying out filtering and denoising processing on the receiving value in the channel range to obtain a denoised receiving value.
7. The apparatus for processing CT scan data as recited in claim 6, further comprising:
a third obtaining module, configured to obtain a smaller value of a maximum receiving value of a right-end channel of the first channel interval and a maximum receiving value of a left-end channel of the second channel interval;
the data processing module is specifically configured to perform denoising processing on the received value in the channel range that is smaller than the smaller received value.
8. The apparatus for processing CT scan data according to claim 7, wherein the third acquiring module comprises: a third obtaining submodule and a fourth obtaining submodule;
the third obtaining submodule is configured to obtain a maximum value of receiving values of a first preset number of channels adjacent to a right end channel in the first channel interval before to a second preset number of channels adjacent to the right end channel in the first channel interval after, as the maximum receiving value of the right end channel;
the fourth obtaining submodule is configured to obtain a maximum value of receiving values of a third preset number of channels adjacent to the left end channel in the second channel interval before to a fourth preset number of channels adjacent to the left end channel in the second channel interval after, as the maximum receiving value of the left end channel.
9. The apparatus for processing CT scan data according to any one of claims 6 to 8, wherein the data processing module is configured to perform filtering and de-noising processing on the received values in the channel range by using a bilateral filtering method.
10. A CT machine, comprising: a detector and a computer;
the computer is used for obtaining the eccentricity degree of the mold body according to the centroid position and the central channel position of the detector receiving values corresponding to all channels of the current layer of the current scanning angle;
when the eccentricity degree is larger than a preset eccentricity value, obtaining a channel range needing denoising treatment according to the eccentricity degree, wherein the channel range is in direct proportion to the eccentricity degree; the method specifically comprises the following steps: obtaining the number of channels which do not need denoising processing according to the eccentricity degree and the preset number of channels, wherein the preset number of channels is related to a shape filter of the CT machine; obtaining a channel range needing denoising processing according to the number of channels not needing denoising processing, wherein the channel range needing denoising processing comprises a first channel interval [1, m-N ] and a second channel interval [ m + N, N ]; wherein m is a central channel, N is a half of the number of channels which do not need denoising processing, and N is the number of all channels of the current layer of the current scanning angle;
and carrying out filtering and denoising treatment on the received value in the channel range to obtain a denoised received value.
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