CN109770935B - Collimator correction method and device, CT system and storage medium - Google Patents
Collimator correction method and device, CT system and storage medium Download PDFInfo
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- CN109770935B CN109770935B CN201811627437.2A CN201811627437A CN109770935B CN 109770935 B CN109770935 B CN 109770935B CN 201811627437 A CN201811627437 A CN 201811627437A CN 109770935 B CN109770935 B CN 109770935B
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Abstract
The embodiment of the invention discloses a collimator correction method, a collimator correction device, a CT system and a storage medium, wherein the method comprises the following steps: respectively acquiring current code values corresponding to the first blade and the second blade moving to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis; the first blade and the second blade in the collimator move along the reference axis; and determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value. By adopting the technical scheme, when the CT system is used for scanning, mechanical errors caused by the installation process of the bulb tube, the collimator and the detector array can be compensated, and the imaging quality of the CT image is improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of medical instruments, in particular to a collimator correction method, a collimator correction device, a CT system and a storage medium.
Background
In clinical Computed Tomography (CT) imaging, X-rays are irradiated on a human body to obtain images of the X-rays attenuated by various tissues of the human body according to different degrees of attenuation of the X-rays by different tissues or organs of the human body, and the images are used as reference bases for disease diagnosis.
Referring to fig. 1A, in order to reduce the interference of scattered rays, reduce the radiation dose of a patient, and improve the imaging quality of a CT image during a CT imaging process, a collimator 120 is generally disposed between a bulb 110 and a detector array 130 for collimating X-rays emitted from the bulb. The collimator 120 includes a first blade and a second blade, and is configured to determine a width of a collimating slit formed by the relative movement of the first blade and the second blade along the same reference axis, so as to collimate the X-ray emitted by the bulb 110.
However, because there is a certain mechanical error in the installation process of the bulb 110, the collimator 120 and the detector array 130, when scanning imaging is performed by using the CT system, the imaging quality of the CT image is affected because the position of the collimator 120 and the width of the collimation slit formed by the first blade and the second blade are not accurate.
Disclosure of Invention
The invention provides a collimator correction method, a collimator correction device, a CT system and a storage medium, which are used for compensating mechanical errors of the CT system so as to improve the imaging quality of a CT image.
In a first aspect, an embodiment of the present invention provides a collimator correction method, which is applied to a CT system including a bulb, a collimator, and a detector array, wherein the collimator includes a first blade and a second blade, and the first blade and the second blade move along a same reference axis, and the collimator correction method includes:
respectively acquiring current code values corresponding to the first blade and the second blade moving to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis;
and determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
In a second aspect, an embodiment of the present invention further provides a collimator calibration apparatus configured in a CT system, where the CT system includes a bulb, a collimator, and a detector array, where the collimator includes a first blade and a second blade, and the first blade and the second blade move along a same reference axis, and the collimator calibration apparatus includes:
the current code value acquisition module is used for respectively acquiring current code values corresponding to the first blade and the second blade when the first blade and the second blade move to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis;
and the correction value determining module is used for determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
In a third aspect, an embodiment of the present invention further provides a CT system, including a bulb, a collimator, and a detector, further including:
one or more processors;
storage means for storing one or more programs;
the one or more programs are executed by the one or more processors, so that the one or more processors implement a collimator correction method as provided in an embodiment of the first aspect.
In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements a collimator correction method as provided in the embodiment of the first aspect.
The method comprises the steps of respectively obtaining corresponding current code values when a first blade and a second blade move to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis; and determining a correction value according to the difference value between the current code values of the first blade and the second blade in the collimator and the corresponding preset code values respectively, so as to correct the position of the collimator according to the correction value. By adopting the technical scheme, the technical problem that the imaging quality of the CT image is influenced due to the fact that the position of the collimation slit and the width of the collimation slit formed by the first blade and the second blade of the collimator are inaccurate due to mechanical errors caused by the installation process of the bulb tube, the collimator and the detector array in the prior art is solved, so that the mechanical errors are compensated when the CT system is used, and the imaging quality of the CT image is improved.
Drawings
FIG. 1A is a schematic diagram of a hardware configuration of a CT system;
FIG. 1B is a flowchart illustrating a collimator calibration method according to an embodiment of the present invention;
FIG. 2 is a flowchart of a collimator calibration method according to a second embodiment of the present invention;
fig. 3A is a flowchart of a collimator calibration method according to a third embodiment of the present invention;
FIG. 3B is a ray intensity diagram corresponding to each row of detectors in the third embodiment of the present invention;
fig. 4 is a schematic structural diagram of a collimation slit correction device in the fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of a CT system in a fifth embodiment of the invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1B is a flowchart of a collimator calibration method according to an embodiment of the invention. The present invention is applicable to the case of compensating for mechanical errors in the CT system shown in fig. 1A. The method is performed by a collimator calibration apparatus, which is implemented by software and/or hardware and is configured in a CT system. Referring to fig. 1A, the CT system includes a bulb 110, a collimator 120, and a detector array 130, wherein the collimator 120 includes a first blade and a second blade, and the first blade and the second blade move along a same reference axis.
A collimator correction method as shown in fig. 1B, comprising:
and S110, respectively acquiring current code values corresponding to the first blade and the second blade when the first blade and the second blade move to a target closing point.
Referring to fig. 1A, the target closing point O is an intersection point of a line connecting the focal point S of the bulb 110 and the target point D of the detector array 130 and the reference axis.
Illustratively, the target point D may be a center point of the detector array; accordingly, the target closing point O is the intersection of the reference axis and the line connecting the focal point S of the bulb 110 and the target point D of the detector array 130.
For example, a first current code value of a driving motor controlling the first blade when the first blade moves to the target closing point and a second current code value of a driving motor controlling the second blade when the second blade moves to the target closing point may be directly acquired; the first blade and the second blade can be controlled to move to the target closing point respectively, and then the first current code value of the driving motor of the first blade and the second current code value of the driving motor of the second blade are acquired.
And S120, determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
When the preset code value is that the calculated first blade and the calculated second blade are installed at the theoretical installation position, a first theoretical code value corresponding to a driving motor of the first blade and a second theoretical code value corresponding to a driving motor of the second blade are obtained.
Specifically, a first correction code value is determined according to a difference value between a first current code value and a first theoretical code value corresponding to the first blade, so that the setting position of the first blade of the collimator is corrected according to the first correction code value; and determining a second correction code value according to the difference value between the second current code value and the second theoretical code value corresponding to the second blade, so as to correct the setting position of the second blade of the collimator according to the second correction code value. It is to be understood that the first correction code value and the second correction code value may be positive or negative values.
It will be appreciated that, in order to improve the accuracy of the determined correction values, it is also possible to repeat the determination of the correction values a plurality of times for a first blade and a second blade of the same CT system; the final correction value of the first blade is determined according to the average value of the correction values corresponding to the first blade, and the final correction value of the second blade is determined according to the average value of the correction values corresponding to the second blade.
Optionally, correcting the position of the collimator according to the correction value includes: acquiring a required collimation slit width, and determining a first initial code value corresponding to the first blade and a second initial code value corresponding to the second blade according to the required collimation slit width; acquiring a correction value corresponding to a first blade, acquiring a first target code value by combining the first initial code value, acquiring a correction value corresponding to a second blade, and acquiring a second target code value by combining the second initial code value; controlling the first blade to move to the first target code value and controlling the second blade to move to the second target code value.
Specifically, before scanning by using a CT system, according to the required width of a collimation slit, determining a first initial code value and a second initial code value corresponding to theoretical setting positions of a corresponding first blade and a corresponding second blade; acquiring a first correction code value of a first blade, and calculating the sum of the first correction code value and a first initial code value to obtain a first target code value; acquiring a second correction code value of the second blade, and calculating the sum of the second correction code value and the second initial code value to obtain a second target code value; and controlling a driving motor of the first blade to drive the first blade to a position corresponding to the first target code value, and controlling a driving motor of the second blade to drive the second blade to a position corresponding to the second target code value.
For example, after the correction values are determined, the correction values of the blades may be stored in correspondence with the corresponding first blades or second blades, that is, the first correction code values are stored in correspondence with the first blades, and the second correction code values are stored in correspondence with the second blades, so that the correction values corresponding to the first blades and the second blades can be directly acquired each time the collimator is adjusted.
In particular, the correction code values may be stored locally on the CT system, or in other storage devices or cloud ends associated with the CT system. The collimator adjustment may be performed by adjusting the collimator to a required collimator slit width each time the CT system is used for scanning.
It is understood that, because the mechanical error of the CT system itself changes due to the loss of hardware in the CT system or due to the repair or replacement of the bulb, the collimator and the detector array in the CT system, the above situation requires the re-determination of the correction value or further updating and storing of the correction value to match the current CT system.
Of course, in order to reduce the calculation amount when the CT system adjusts the collimation slit width, the calibration values of the blades may be directly used to update the collimation slit width tables stored in the CT system for reading after determining the calibration values. The quasi-straight slit width table stores theoretical code values of the first blade and theoretical code values of the second blade corresponding to the quasi-straight slit widths in advance. Specifically, the theoretical code value of the first blade corresponding to each width of the collimating slit may be updated according to the sum of the correction value of the first blade and each theoretical code value of the first blade; and updating the theoretical code value of the second blade corresponding to each collimation slit width according to the sum of the correction value of the second blade and each theoretical code value of the second blade.
The method comprises the steps of respectively obtaining corresponding current code values when a first blade and a second blade move to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis; and determining a correction value according to the difference value between the current code values of the first blade and the second blade in the collimator and the corresponding preset code values respectively, so as to correct the position of the collimator according to the correction value. By adopting the technical scheme, the technical problem that the imaging quality of the CT image is influenced due to the fact that the position of the collimation slit and the width of the collimation slit formed by the first blade and the second blade of the collimator are inaccurate due to mechanical errors caused by the installation process of the bulb tube, the collimator and the detector array in the prior art is solved, so that the mechanical errors are compensated when the CT system is used, and the imaging quality of the CT image is improved.
Example two
Fig. 2 is a flowchart of a collimator calibration method according to a second embodiment of the present invention. The embodiment of the invention performs additional optimization on the basis of the technical scheme of each embodiment.
Further, before operation of respectively obtaining current code values corresponding to the first blade and the second blade moving to a target closing point, additionally obtaining scanning data and determining a target detector array capable of receiving rays according to the scanning data; determining a first distance between the first blade and the target closing point and a second distance between the second blade and the target closing point according to the position relation among the bulb, the first blade, the second blade and the target detector array; and respectively controlling the first blade and the second blade to move to the target closing point' according to the first distance and the second distance so as to determine the distance required to move between the first blade and the second blade to the target closing point, and controlling the movement of the first blade and the second blade according to the determined distance.
A collimator correction method as shown in fig. 2, comprising:
s210, acquiring scanning data and determining a target detector array capable of receiving rays according to the scanning data.
Specifically, scanning data of the collimator at the current position is obtained, and the ray intensity corresponding to each detector is determined according to the scanning data; when the ray intensity is smaller than a set threshold value, indicating that the corresponding detector is shielded; when the ray intensity is not less than the set threshold, indicating that the corresponding detector is not shielded; and determining each detector which is not blocked as a target detector array. The set threshold may be set by a technician according to an empirical value, or the corresponding scan data may be acquired when the bulb tube does not emit radiation, and the reference radiation intensity of the scan data is determined, and the reference radiation intensity is used as the set threshold. The scan data may be, for example, scan data generated when scanning an air medium or a pin die.
S220, respectively determining a first distance between the first blade and the target closing point and a second distance between the second blade and the target closing point according to the position relation among the bulb, the first blade, the second blade and the target detector array.
Specifically, according to a first design distance between the bulb and the reference axis and a second design distance between the bulb and the detector array, determining a collimation slit distance corresponding to the target detector array; determining the first distance and the second distance according to the number ratio of the detectors of the target detector array distributed in the first direction and the second direction of the target point and the collimation slit distance; the first direction is a side of the target point far away from the second blade, and the second direction is a side of the target point far away from the first blade.
Referring to the schematic diagram of the CT system shown in FIG. 1A, a collimation slit distance l corresponding to the target detector array is determined based on a first design distance SBD between the sphere tube 110 and the reference axis of the collimator 120 and a second design distance SDD between the sphere tube 110 and the detector array 130. Specifically, the width L of the target detector array is determined according to the number of detector rows included in the target detector array and the width of each detector row; a first mapping ratio is determined based on a ratio between the first design distance SBD and the second design distance SDD, and the collimation slit distance L is determined based on a product of the first mapping ratio and the width L of the object detector array.
Specifically, a second mapping ratio is determined according to the ratio of the number of rows of detectors in the target detector array distributed in the first direction (corresponding to the left side in fig. 1A) and the second direction (corresponding to the right side in fig. 1A) of the target point D, and a first distance l of the first blade from the target point D is determined according to the product of the second mapping ratio and the collimation slit distance l1And a second distance l of the second blade from the target point D2。
And S230, respectively controlling the first blade and the second blade to move to the target closing point according to the first distance and the second distance.
Specifically, a first value to be adjusted of the drive motor of the first blade is determined according to the first distance, and a second value to be adjusted of the drive motor of the second blade is determined according to the second distance. And controlling the first blade to move to the target closing point according to the first code value to be adjusted, and controlling the second blade to move to the target closing point according to the second code value to be adjusted.
When each vane is moved to the target closing point, the number of movements may be set as needed, and for example, the first vane may be moved once to the target closing point and moved once to the target closing point via the second vane. Of course, in order to improve the degree of contact between the closed positions of the first and second vanes and the target closing point and thus improve the accuracy of the determined correction value, the first and second vanes may be moved a plurality of times, respectively.
Illustratively, controlling the first blade and the second blade to move to the target closing point according to the first distance and the second distance, respectively, may be: controlling one of the blades to move towards the target closing point, acquiring first current scanning data, and determining the ray intensity corresponding to each row of detectors in a first target detector array according to the first current scanning data; controlling the other blade to move towards the target closing point, acquiring second current scanning data, and determining the ray intensity corresponding to each row of detectors in a second target detector array according to the second current scanning data; continuously controlling each blade to move towards the target closing point until the ray intensity corresponding to each row of detectors in the first target detector array is smaller than a set threshold value, and the ray intensity corresponding to each row of detectors in the second target detector array is smaller than the set threshold value; the first target detector array is a detector of which the target detector array is distributed in a first direction of the target point; the second target detector array is a detector in which the target detector array is distributed in a second direction of the target point.
Optionally, controlling one of the vanes to move to the target closing point and controlling the other of the vanes to move to the target closing point may be: and obtaining a first preset adjusting step length, moving the first blade to the target closing point according to the first preset adjusting step length, obtaining a second preset adjusting step length, and moving the second blade to the target closing point according to the second preset adjusting step length. It is understood that the first preset adjustment step size and the second preset adjustment step size may be the same or different.
Or optionally, before controlling one of the vanes to move to the target closing point and controlling the other vane to move to the target closing point, the method further includes: and respectively determining a first adjusting step length of the first blade and a second adjusting step length of the second blade according to the preset adjusting ratios corresponding to the first blade and the second blade and the first distance and the second distance. Correspondingly, controlling one of the vanes to move to the target closing point and controlling the other vane to move to the target closing point may further include: controlling the first blade to move the first adjustment step toward the target closing point, and controlling the second blade to move the second adjustment step toward the target closing point.
Optionally, when the first blade and the second blade are moved to the target closing point, after the first blade is moved a single time and/or the second blade is moved a single time, the scanning data acquisition is performed again, and the target detector array capable of receiving the ray is determined according to the scanning data until the first blade and the second blade are closed at the target closing point. Specifically, determining that the first blade and the second blade are closed at the target closing point may be: and determining that the intensity of the ray corresponding to each row of detector arrays in the first target detector array is smaller than a set threshold value, and determining that the intensity of the ray corresponding to each row of detectors in the second target detector array is smaller than the set threshold value. Wherein the first target detector array is a detector of which the target detector array is distributed in a first direction of the target point (corresponding to the left side of point D in fig. 1A); the second target detector array is a detector in which the target detector array is distributed in a second direction of the target point (corresponding to the right side of point D in fig. 1A).
It will be appreciated that, in order to avoid the situation where the first blade obscures the detector in the second direction, or the second blade obscures the detector in the first direction, which may result in the actual closed point of the first blade and the second blade not matching the target closed point, it is preferable that the acquisition of the scan data and the determination of the target detector array are performed each time the blade is moved until the first blade obscures and obscures only the first target detector array, and the second blade obscures and obscures only the second target detector array.
Of course, in order to timely remedy when the first blade blocks the second target detector array or the second blade blocks the first target detector array, the first blade may be moved toward the first direction of the target closing point (corresponding to the left side of the point D in fig. 1A) or the second blade may be moved toward the second direction of the target closing point (corresponding to the right side of the point D in fig. 1A) until the first blade blocks and blocks only the first target detector array and the second blade blocks and blocks only the second target detector array. The specific moving step length can determine a code value to be adjusted by determining the distance between the current position of each blade and a target closing point, and each blade is moved once according to the determined code value to be adjusted; or moving each blade for multiple times according to the code value to be adjusted and the step length to be adjusted; or determining the step length to be recalled of each blade moved each time according to the preset recall ratio and the value of the code to be recalled, and moving each blade respectively according to the determined step length to be recalled each time.
S240, respectively acquiring current code values corresponding to the first blade and the second blade moving to the target closing point.
And S250, determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
According to the embodiment of the invention, before the current code values corresponding to the first blade and the second blade moving to the target closing point are respectively obtained, the first distance between the first blade and the target closing point and the second distance between the second blade and the target closing point are determined, and the first blade and the second blade are respectively controlled to move to the target closing point based on the determined first distance and second distance, so that the moving mode of each blade is perfected, the first blade and the second blade are closed at the target closing point position in a single-time moving or multiple-time moving mode, and a foundation is laid for determining the correction value.
EXAMPLE III
Fig. 3A is a flowchart of a collimator calibration method according to a third embodiment of the present invention. The embodiment of the invention provides a preferable implementation mode on the basis of the technical scheme of each embodiment.
A collimator correction method as shown in fig. 3A, comprising:
s301, scanning the air medium to obtain current scanning data, and determining the ray intensity of each detector according to the current scanning data.
S302, determining the detector with the ray intensity not less than the set threshold value as a target detector array.
And setting the threshold value as the ray intensity corresponding to the scanning data obtained by collecting the air medium when the bulb tube does not emit rays. See the corresponding ray intensity diagram for each row of detectors shown in fig. 3B. The abscissa is the number of detector rows, the ordinate is the ray intensity, and offset corresponds to a set threshold. The target detector array is a detector array formed by 142-218 rows of detectors.
S303, determining a first mapping ratio according to the ratio of the distance between the focal point of the bulb and the reference axis of the collimator blade to the distance between the focal point of the bulb and the detector array.
See FIG. 1A, according to formula
A first mapping ratio alpha is determined, where SBD is the distance between the focal point of the bulb and the reference axis of the collimator leaves and SDD is the distance between the focal point of the bulb and the detector array.
S304, determining the product of the width value of the target detector array and the first mapping ratio, and determining the width of the collimation slit.
Referring to fig. 1A, a collimation slit width L is determined according to the formula L ═ α × L, where L is a width value of the target detector array.
S305, determining the ratio of the number of detectors on the left side of the target point to the number of detectors on the right side of the target point in the target detector array according to the target point of the detector array, wherein the ratio is a second mapping ratio.
Referring to fig. 1A, the target point of the detector array is a point D, and the number of detectors may be the number of detectors or the number of detector rows. Since the width of each row of detectors is the same and the number of detectors in each row is the same, the width L of the target detector array located to the left of the target point D can be characterized by the second mapping ratio1Width L of target detector array located at right side of target point D2The ratio of (a) to (b).
S306, determining a first distance between the left collimating blade and the target closing point and a second distance between the right collimating blade and the target closing point according to the second mapping ratio and the width of the collimating slit.
In particular, according to the formula
Determining a first distance l1And a second distance l2。
S307, determining a first adjusting step length according to a preset first adjusting ratio and the first distance, and determining a second adjusting step length according to a preset second adjusting ratio and the second distance.
In particular, according to the formula
Determining a first adjustment step Δ l1And a second adjustment step Δ l2。
And S308, controlling the left collimating blade to move the corresponding code value to the target closing point according to the first adjusting step length, and controlling the right collimating blade to move the corresponding code value to the target closing point according to the second adjusting step length.
S309, after the blade moves, judging whether the left collimating blade and the right collimating blade are just closed at a target closing point; if so, go to step S310, otherwise, go back to step S301.
Specifically, after the left collimating blade is moved, whether each detector on the left side of the target closing point is only shielded by the left collimating blade is judged; after the right collimating blade is moved, whether each detector on the right side of the target closing point is only shielded by the right collimating blade is judged. When the target closing point is shielded by the detectors, the ray intensity of each shielded detector is smaller than a set threshold value.
S310, respectively obtaining corresponding current code values when the left collimating blade and the right collimating blade move to the target closing point.
S311, determining the corresponding correction values of the left and right collimating leaves according to the current code values of the left and right collimating leaves and the difference value between the corresponding preset code values.
Example four
Fig. 4 is a schematic structural diagram of a collimation slit correction device in the fourth embodiment of the present invention. The present invention is applicable to the case of compensating for mechanical errors in the CT system shown in fig. 1A, which is implemented by software and/or hardware and configured in the CT system. The CT system comprises a bulb tube, a collimator and a detector array, wherein the collimator comprises a first blade and a second blade, and the first blade and the second blade move along the same reference axis.
A collimator correction device as shown in fig. 4, comprising: a current code value acquisition module 410 and a correction value determination module 420.
The current code value obtaining module 410 is configured to obtain current code values corresponding to the first blade and the second blade moving to a target closing point respectively; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis;
and a correction value determining module 420, configured to determine a correction value according to a difference between the current code values of the first blade and the second blade and the corresponding preset code values, so as to correct the collimator position according to the correction value.
According to the embodiment of the invention, the current code values corresponding to the target closing points of the first blade and the second blade which are moved to the target closing points are respectively obtained through the current code value obtaining module; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis; and determining a correction value according to the current code values of the first blade and the second blade in the collimator and the difference value between the corresponding preset code values through a correction value determining module so as to correct the position of the collimator according to the correction value. By adopting the technical scheme, the technical problem that the imaging quality of the CT image is influenced due to the fact that the position of the collimation slit and the width of the collimation slit formed by the first blade and the second blade of the collimator are inaccurate due to mechanical errors caused by the installation process of the bulb tube, the collimator and the detector array in the prior art is solved, so that the mechanical errors are compensated when the CT system is used, and the imaging quality of the CT image is improved.
Further, the apparatus further comprises:
the target detector array acquisition module is used for acquiring scanning data and determining a target detector array capable of receiving rays according to the scanning data before the current code values corresponding to the first blade and the second blade moving to the target closing point are acquired respectively;
a distance determining module, configured to determine, according to a positional relationship among the bulb, the first blade, the second blade, and the target detector array, a first distance between the first blade and the target closing point, and a second distance between the second blade and the target closing point, respectively;
and the blade moving module is used for respectively controlling the first blade and the second blade to move to the target closing point according to the first distance and the second distance.
Further, the distance determination module includes:
a collimation slit distance determining unit, configured to determine a collimation slit distance corresponding to the target detector array according to a first design distance between the bulb and the reference axis and a second design distance between the bulb and the detector array;
a distance determining unit, configured to determine the first distance and the second distance according to a ratio of the number of detectors of the target detector array distributed in the first direction and the second direction of the target point, and the collimation slit distance;
the first direction is a side of the target point far away from the second blade, and the second direction is a side of the target point far away from the first blade.
Further, the blade moving module includes:
the ray intensity determining unit is used for controlling one of the blades to move towards the target closing point, acquiring first current scanning data and determining the ray intensity corresponding to each row of detectors in the first target detector array according to the first current scanning data; controlling the other blade to move towards the target closing point, acquiring second current scanning data, and determining the ray intensity corresponding to each row of detectors in a second target detector array according to the second current scanning data;
the circulating unit is used for continuously controlling each blade to move towards the target closing point until the ray intensity corresponding to each row of detectors in the first target detector array is smaller than a set threshold value, and the ray intensity corresponding to each row of detectors in the second target detector array is smaller than the set threshold value;
the first target detector array is a detector of which the target detector array is distributed in a first direction of the target point; the second target detector array is a detector in which the target detector array is distributed in a second direction of the target point.
Further, the radiation intensity determining unit, before controlling one of the blades to move to the target closing point and controlling the other of the blades to move to the target closing point, is specifically configured to:
respectively determining a first adjusting step length of the first blade and a second adjusting step length of the second blade according to preset adjusting ratios corresponding to the first blade and the second blade and the first distance and the second distance;
correspondingly, the radiation intensity determining unit, when controlling one of the blades to move to the target closing point and controlling the other of the blades to move to the target closing point, is specifically configured to:
controlling the first blade to move the first adjustment step toward the target closing point, and controlling the second blade to move the second adjustment step toward the target closing point.
Further, the apparatus further comprises:
and the correction module is used for correcting the position of the collimator according to the correction value.
Further, a correction module, comprising:
an initial code value determining unit, configured to obtain a required quasi-straight slit width, and determine a first initial code value corresponding to the first blade and a second initial code value corresponding to the second blade according to the required quasi-straight slit width;
the target code value obtaining unit is used for obtaining a correction value corresponding to a first blade, obtaining a first target code value by combining the first initial code value, obtaining a correction value corresponding to a second blade, and obtaining a second target code value by combining the second initial code value;
a blade moving unit for controlling the first blade to move to the first target code value and controlling the second blade to move to the second target code value.
Further, the apparatus further comprises a storage module configured to:
before the correction value corresponding to the first blade is acquired and the correction value corresponding to the second blade is acquired, the correction value of each blade is stored corresponding to the corresponding first blade or second blade.
The collimator correction device can execute the collimator correction method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects for executing the collimator correction method.
EXAMPLE five
Fig. 5 is a schematic structural diagram of a CT system in a fifth embodiment of the present invention, where the CT system includes a bulb 510, a collimator 520, and a detector array 530, and further includes:
one or more processors 540;
a storage 550 for storing one or more programs.
In fig. 5, a processor 540 is taken as an example, the processor 540 in the CT system is respectively connected to the tube 510, the collimator 520 and the detector array 530 by a bus or other means, and the processor 540 and the storage 550 are also connected by a bus or other means. Fig. 5 illustrates an example of connection via a bus.
In this embodiment, the processor 540 in the CT system may respectively obtain current code values corresponding to the first blade and the second blade in the collimator 520 moving to the target closing point; wherein the target closing point is an intersection point of a connecting line of a focal point of the bulb 510 and a target point of the detector array 530 and a reference axis in the collimator 520; wherein the first and second leaves in the collimator move relative to each other along the reference axis; correction values can also be determined according to the current code values of the first and second blades in the collimator 520 and the difference values between the preset code values corresponding to the first and second blades stored in the storage device 550, respectively, so as to correct the collimator position according to the correction values.
The storage device 550 in the CT system, as a computer-readable storage medium, may be used to store one or more programs, which may be software programs, computer-executable programs, and modules, such as program instructions/modules corresponding to the collimator correction method in the embodiment of the present invention (for example, the current code value acquisition module 410 and the correction value determination module 420 shown in fig. 4). The processor 540 executes various functional applications and data processing of the CT system by executing software programs, instructions and modules stored in the storage device 550, namely, implements the collimator correction method in the above method embodiment.
The storage 550 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data and the like (the current code value, the preset code value, the correction value, and the like in the above-described embodiments). Further, the storage 550 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, the storage 550 may further include memory located remotely from the processor 540, which may be connected to a server over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a collimator correction apparatus, implements a collimator correction method provided in the embodiments of the present invention, and the method includes: respectively acquiring current code values corresponding to the first blade and the second blade moving to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis; and determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A collimator correction method is applied to a CT system, the CT system comprises a bulb tube, a collimator and a detector array, wherein the collimator comprises a first blade and a second blade, and the first blade and the second blade move along the same reference axis, and the collimator correction method comprises the following steps:
respectively acquiring current code values corresponding to the first blade and the second blade moving to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis;
and determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
2. The method of claim 1, further comprising, prior to said separately obtaining current code values corresponding to the first and second blades moving to a target closing point:
acquiring scanning data and determining a target detector array capable of receiving rays according to the scanning data;
determining a first distance between the first blade and the target closing point and a second distance between the second blade and the target closing point according to the position relation among the bulb, the first blade, the second blade and the target detector array;
controlling the first blade and the second blade to move to the target closing point according to the first distance and the second distance respectively.
3. The method of claim 2, wherein determining a first distance between the first blade and the target closing point and a second distance between the second blade and the target closing point from the positional relationship between the bulb, the first blade, the second blade, and the target detector array, respectively, comprises:
determining a collimation slit distance corresponding to the target detector array according to a first design distance between the bulb and the reference axis and a second design distance between the bulb and the detector array;
determining the first distance and the second distance according to the number ratio of the detectors of the target detector array distributed in the first direction and the second direction of the target point and the collimation slit distance;
the first direction is a side of the target point far away from the second blade, and the second direction is a side of the target point far away from the first blade.
4. The method of claim 2, wherein controlling the first and second blades to move to the target closing point as a function of the first and second distances, respectively, comprises:
controlling one of the blades to move towards the target closing point, acquiring first current scanning data, and determining the ray intensity corresponding to each row of detectors in a first target detector array according to the first current scanning data; controlling the other blade to move towards the target closing point, acquiring second current scanning data, and determining the ray intensity corresponding to each row of detectors in a second target detector array according to the second current scanning data;
continuously controlling each blade to move towards the target closing point until the ray intensity corresponding to each row of detectors in the first target detector array is smaller than a set threshold value, and the ray intensity corresponding to each row of detectors in the second target detector array is smaller than the set threshold value;
the first target detector array is a detector of which the target detector array is distributed in a first direction of the target point; the second target detector array is a detector in which the target detector array is distributed in a second direction of the target point.
5. The method of claim 4, further comprising, prior to controlling one of the vanes to move toward the target closing point and controlling another of the vanes to move toward the target closing point:
respectively determining a first adjusting step length of the first blade and a second adjusting step length of the second blade according to preset adjusting ratios corresponding to the first blade and the second blade and the first distance and the second distance;
accordingly, controlling one of the vanes to move toward the target closing point and controlling the other of the vanes to move toward the target closing point comprises:
controlling the first blade to move the first adjustment step toward the target closing point, and controlling the second blade to move the second adjustment step toward the target closing point.
6. The method of any of claims 1-5, wherein said correcting said collimator position according to said correction value comprises:
acquiring a required collimation slit width, and determining a first initial code value corresponding to the first blade and a second initial code value corresponding to the second blade according to the required collimation slit width;
acquiring a correction value corresponding to a first blade, acquiring a first target code value by combining the first initial code value, acquiring a correction value corresponding to a second blade, and acquiring a second target code value by combining the second initial code value;
controlling the first blade to move to the first target code value and controlling the second blade to move to the second target code value.
7. The method of claim 6, further comprising, prior to obtaining the correction value for the first blade and obtaining the correction value for the second blade:
and storing the correction value of each blade corresponding to the corresponding first blade or second blade.
8. A collimator correction device configured for a CT system, the CT system including a bulb, a collimator, and a detector array, wherein the collimator includes a first blade and a second blade, and the first blade and the second blade move along a same reference axis, the collimator correction device comprising:
the current code value acquisition module is used for respectively acquiring current code values corresponding to the first blade and the second blade when the first blade and the second blade move to a target closing point; the target closing point is the intersection point of a connecting line of a focal point of the bulb and a target point of the detector array and the reference axis;
and the correction value determining module is used for determining a correction value according to the difference value between the current code value of the first blade and the current code value of the second blade and the corresponding preset code value, so as to correct the position of the collimator according to the correction value.
9. A CT system comprising a bulb, a collimator, and a detector array, further comprising:
one or more processors;
storage means for storing one or more programs;
the one or more programs are executable by the one or more processors to cause the one or more processors to implement a collimator correction method as recited in any one of claims 1-7.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out a collimator correction method as claimed in any one of claims 1 to 7.
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| CN111077562B (en) * | 2019-12-20 | 2022-12-16 | 上海联影医疗科技股份有限公司 | Beam offset determination method, device, equipment and storage medium |
| WO2021139088A1 (en) * | 2020-06-10 | 2021-07-15 | 上海西门子医疗器械有限公司 | Method and device for determining target position of single-slot collimating plate, and collimator assembly |
| CN111759343A (en) * | 2020-07-22 | 2020-10-13 | 上海优医基医疗影像设备有限公司 | Position calibration method of collimator in three-in-one equipment upper head side shooting mode |
| US11864941B2 (en) | 2021-10-04 | 2024-01-09 | GE Precision Healthcare LLC | System and method for collimator screening in a computed tomography system |
| CN113749685B (en) * | 2021-10-22 | 2023-10-27 | 上海联影医疗科技股份有限公司 | Leaf optimization method of collimator, radiation treatment plan conversion method and system |
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