CN113975660B - Tumor target area displacement monitoring method and equipment - Google Patents

Tumor target area displacement monitoring method and equipment Download PDF

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CN113975660B
CN113975660B CN202111279965.5A CN202111279965A CN113975660B CN 113975660 B CN113975660 B CN 113975660B CN 202111279965 A CN202111279965 A CN 202111279965A CN 113975660 B CN113975660 B CN 113975660B
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marker
image
tumor target
ellipse
points
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CN113975660A (en
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侯再红
王妍璐
何枫
程乙轮
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Hefei Institutes of Physical Science of CAS
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Hefei Institutes of Physical Science of CAS
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    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1001—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy using radiation sources introduced into or applied onto the body; brachytherapy
    • A61N5/1002—Intraluminal radiation therapy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1049—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam
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    • G06T7/0012—Biomedical image inspection
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    • G06T7/00—Image analysis
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    • G06T7/12—Edge-based segmentation
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    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G06T7/73—Determining position or orientation of objects or cameras using feature-based methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1049—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam
    • A61N2005/1059—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam using cameras imaging the patient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1092—Details
    • A61N2005/1096—Elements inserted into the radiation path placed on the patient, e.g. bags, bolus, compensators
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10072—Tomographic images
    • G06T2207/10081—Computed x-ray tomography [CT]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
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    • G06T2207/30096—Tumor; Lesion

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Abstract

The invention provides a tumor target area displacement monitoring method and equipment, wherein the method comprises the following steps: step S1: setting a treatment point on the thermoplastic film, wherein the treatment point is a radiation position of radiotherapy; positioning a marker, wherein the position of the marker corresponds to a tumor target area; step S2: and calculating the displacement value of the tumor target area according to the relative displacement value of the marker and the treatment point. The invention can realize the real-time monitoring of the displacement of the tumor target area when a certain movable space appears between the thermoplastic film and the patient.

Description

Tumor target area displacement monitoring method and equipment
Technical Field
The invention relates to the technical field of heavy ion radiotherapy, in particular to a tumor target area displacement monitoring method and equipment.
Background
In the treatment of cancer, heavy ion radiation therapy is adopted, so that the cure rate is high, the humanization is realized, and the popularization is rapid. 70% of tumor patients need to receive radiation therapy (hereinafter referred to as radiotherapy) at various stages of tumor progression. In the traditional radiotherapy process, firstly, the position of a tumor target area in a patient body is positioned through CT scanning, then a thermoplastic film customized in shape is covered on the surface of the patient body, a marking point is arranged on the thermoplastic film according to a CT scanning result to mark the position of the tumor, and finally, a radiotherapy ray is aimed at the marking point on the thermoplastic film in the radiotherapy process to carry out radiotherapy on the patient.
However, due to the long time period of radiotherapy, the shape of a patient can be obviously changed in the radiotherapy process, so that the patient has a certain movable space under the thermoplastic film, and a certain error can occur by adopting a method of marking the position of a tumor by setting marking points on the thermoplastic film. When the heavy ion rays are irradiated on healthy tissues, not only the treatment effect is reduced, but also additional side effects are brought to the patient. Researches show that the body position of a patient deviates from 5mm in the radiotherapy process, and the curative effect of the radiotherapy is reduced by 18.4%; the curative effect is reduced by 33.4% when the treatment is shifted by 6 mm. When the offset is larger, the damage to healthy tissue is larger than the treatment of tumor. There is therefore a need for a method or apparatus to address the problem of monitoring tumor target displacement in patients during radiotherapy.
Disclosure of Invention
The invention discloses a tumor target area displacement monitoring method aiming at the defects in the background technology,
The method comprises the following steps:
Step S1: setting a treatment point on the thermoplastic film, wherein the treatment point is a radiation position of radiotherapy; positioning a marker, wherein the position of the marker corresponds to a tumor target area;
step S2: and calculating the displacement value of the tumor target area according to the relative displacement value of the marker and the treatment point.
Preferably, the step of locating the marker comprises:
SA101, extracting feature points on the physical feature markers;
SA102, matching the displacement of the characteristic points in the real-time image and the reference image by adopting a characteristic point matching algorithm, and positioning the marker.
Preferably, the marker is a geometric marker;
the step of locating the marker comprises:
SA111, dividing the marker from the background;
SA112, marking the outline of the marker by adopting a fitting algorithm;
SA113, determining the geometric center position of the marker, and positioning the marker.
Preferably, wherein the color of the marker adopts one of three primary colors;
step SA111 specifically includes the steps of:
SA1111, splitting the collected color image into three gray scale images of red, green and blue channels respectively;
SA1112, subtracting the gray value of the pixel corresponding to the color channel passing through the marker from the gray value of the pixel corresponding to the other two channels in the image.
Preferably, the step SA112 specifically includes:
SA1121: calculating the outline of the gray level map containing the markers by using a Canny algorithm;
SA1122: removing contours with areas smaller than a set threshold value from the contours;
SA1123: and (3) calculating convex hulls for all the outlines of each marker, and calculating to obtain the outline of each marker.
Preferably, step SA113 specifically includes the following steps:
SA1131: extracting points on the outer contour of the marker;
SA1132: fitting an ellipse by adopting a least square method;
SA1133: calculating the distance from all fitting points to the center of the fitted ellipse, and eliminating noise points with abnormal distance by adopting a Grabbs criterion;
SA1134: fitting the ellipse by adopting a least square method again;
SA1135: judging whether noise points are contained or not; if the noise point is included, the process goes back to step SA1133, and if the noise point is not present, the marker is positioned by the ellipse center.
Preferably, the method further comprises step SA1136: and taking the center of the ellipse as the center, taking a rectangular area with the length and the width of a preset multiple of the ellipse axis as an interested area of the next frame of image, wherein the image after the interested area representation only carries out ellipse fitting in the interested area.
In another embodiment of the present invention, there is also disclosed a tumor target displacement monitoring apparatus, the apparatus comprising:
an image acquisition unit for acquiring an image, wherein the image acquisition unit coaxially mounts an annular light source of small divergence angle and disposes with the marker;
A marker for locating a tumor position, wherein a microprism type reflective film is attached to the surface of the marker;
and the image processing unit is used for processing and calculating the image to obtain tumor target area displacement information.
In another embodiment of the present invention, a computer readable storage medium having a computer program stored thereon is disclosed, the computer program executing any one of the tumor target displacement monitoring methods after running.
In another embodiment of the present invention, a computer device is also disclosed, including a processor, a storage medium, on which a computer program is stored, the processor reading and running the computer program from the storage medium to perform any of the tumor target displacement monitoring methods.
The beneficial effects are that:
(1) The treatment points and the markers corresponding to the positions of the tumor target areas in real time are arranged on the thermoplastic film, the displacement values of the tumor target areas are calculated in real time according to the relative displacement of the treatment points and the markers, the monitoring of the displacement of the tumor target areas is realized, and the radiotherapy effect is improved.
(2) The marker points on the markers can be extracted to position the markers according to the displacement of the marker points.
(3) The marker profile can be more accurately fitted after the marker is cut from the background.
(4) The step of color space conversion is omitted, and the selection of the thresholds of each component under different illumination conditions is not required to be considered.
(5) Eliminating contours less than the set threshold can improve accuracy in locating the markers.
(6) The three-dimensional condition of the human body is considered, noise points are removed, and the positioning accuracy is improved.
(7) Considering that the displacement of the patient is smaller under the fixation of the thermoplastic film, the area for collecting the image is limited, so that the positioning is more accurate and rapid.
Drawings
FIG. 1 is a flowchart of a method for monitoring displacement of a tumor target area according to an embodiment of the present invention;
FIG. 2 is a flow chart of positioning markers according to an embodiment of the present invention;
FIG. 3 is a flowchart of a method for fitting a marker and obtaining a center position of the marker for positioning according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating the operation of a tumor target displacement monitoring apparatus according to an embodiment of the present invention;
FIG. 5a is a schematic view of the path of light emitted from an annular light source when a microprism reflective film is attached to a label in an embodiment of the present invention;
FIG. 5b is a schematic view of the path of light emitted by the annular light source when the marker is diffusely reflected;
FIG. 6 is a graph showing the distribution of markers in an embodiment of the present invention;
FIG. 7a is a schematic view of locating a marker under a thermoplastic film when the marker is in the shape of an X corner;
FIG. 7b is a schematic illustration of positioning a marker under a thermoplastic film when the marker is rectangular;
fig. 7c is a schematic illustration of the positioning of the markers under the thermoplastic film when the markers are circular.
In the figure: 1. an industrial camera; 2. a marker; 21. microprism type reflective film; 3. a patient's body membrane; 4. an annular light source; 5. and (3) a bracket.
Detailed Description
In view of the above problems, an embodiment of the present invention discloses a method for monitoring displacement of a tumor target area, specifically, after a tumor position in a patient is scanned by CT, a marker is fixed at the tumor position on the surface of the patient, and meanwhile, a treatment point is set on a thermoplastic film, and when radiotherapy is performed for the first time, the positions of the treatment points are the same as each other and correspond to the tumor position in the patient. When the next radiotherapy is carried out, due to the change of the body shape or the body position of the patient, the position of the body surface of the patient corresponding to the treatment point can deviate, and the position of the treatment point no longer corresponds to the position of the tumor in the patient. The marker is fixed on the body surface of the patient, and the position of the marker changes along with the change of the body shape of the patient, so that the position of the marker still corresponds to the tumor position in the patient during the next radiotherapy. The marker can be positioned through the ventilation holes formed in the thermoplastic film, and the displacement of the tumor target area can be accurately calculated according to the relative displacement of the marker and the treatment point, so that a new treatment point is obtained. Namely, the tumor position in the patient can be accurately positioned according to the markers, CT scanning is not needed to be carried out again, and a new thermoplastic film is not needed to be customized again. From the above, the invention can better solve the problem that the treatment point deviates from the tumor position in the patient due to the change of the patient's body shape, and in addition, if the patient moves the position in the thermoplastic film during the treatment, the treatment position can be adjusted at the first time.
The present invention will be described in detail below with reference to the accompanying drawings, as shown in fig. 1.
Step S1: setting a treatment point on the thermoplastic film, wherein the treatment point is a radiation position of radiotherapy; and positioning the marker, wherein the marker position corresponds to the tumor target area.
Specifically, in order to avoid patient body movement during radiotherapy, a thermoplastic film is used to fix the patient's body position. The thermoplastic film is formed once according to the shape of a patient, and cannot be adjusted in the later stage. In order to determine the position of a tumor target area, a treatment point is arranged on the thermoplastic film, and when radiotherapy is carried out, radioactive rays aim at the treatment point to carry out radioactive irradiation so as to inactivate cancer cells in a patient. The position represented by the treatment point at the time of the first treatment is the position of the tumor target area. Since the patient does not always remain in a relatively stationary state during the course of treatment, dynamic adjustment of the treatment site is required.
Illustratively, the markers are fixed to the patient's body surface, e.g., the markers may be affixed to the patient's body surface. The position of which corresponds to the tumor position in the patient, i.e. the tumor target area. When the body shape or the body position of the patient changes, the positions of the markers fixed on the body surface of the patient move along with the change, and the positions corresponding to the markers are still tumor positions in the body of the patient. The marker is fixed on the body surface of the patient and covered by the thermoplastic film, can not be observed by naked eyes, and can only be observed through the air holes on the thermoplastic film. Therefore, it is particularly important to accurately locate the markers, and the location related content of the markers will be described in detail in other embodiments of the present invention.
Step S2: and calculating the displacement value of the tumor target area according to the relative displacement value of the marker and the treatment point.
Specifically, the irradiation position of the radiotherapy rays is positioned according to the relative displacement of the marker in the treatment process, the position of the treatment point is taken as the initial position, and the position of the treatment point, namely the irradiation position of the radioactive rays, is adjusted by taking the relative displacement of the marker and the treatment point in the treatment process as the deviation zone.
Illustratively, the position of the marker will change when the patient's body shape or position changes, but the treatment point on the thermoplastic film will not change. Therefore, when the body shape of a patient changes, the displacement value of the tumor target area relative to the original treatment point can be obtained by positioning the marker and then calculating the relative displacement of the original marker and the treatment point, and after the displacement value is obtained, the tumor target area is accurately positioned only by simply changing the position of the treatment point according to the displacement value, so that the tumor cells in the patient are precisely hit. For example, the original treatment point is used as the origin of coordinates, and the coordinates after the marker displacement are (X, Y). Then the point (X, Y) is treated in the subsequent radiotherapy process. In the actual treatment process, the tumor target area is an area, and in the subsequent treatment process, the shape of the area of the tumor target area is kept unchanged, wherein the middle point (X, Y) can be the center point of the tumor target area or any point in the tumor target area, and the relative position of the middle point (X, Y) in the tumor target area is kept unchanged in the front and back treatment processes.
In another embodiment of the invention said markers are geometric markers; as shown in fig. 2, the positioning the marker includes:
step SA111: dividing the marker from the background;
step SA112: adopting a fitting algorithm to mark outlines;
Step SA113: and determining the geometric center position of the marker, and positioning the marker.
Specifically, since the markers are shielded by the thermoplastic film for a large portion during the radiotherapy, the complete markers cannot be observed by optical tracking, and a small portion of the marker profile leaks out of the ventilation holes of the thermoplastic film. Therefore, the outline of the marker needs to be separated from the background so as to locate the marker.
In this embodiment, the color features of the markers are used for segmentation. The color of the marker adopts one of three primary colors, and specifically comprises the following steps:
SA1111: splitting the collected color image into three gray images of three channels of red, green and blue;
SA1112: and subtracting the gray value of the pixel corresponding to the other two channels from the gray value of the pixel corresponding to the marker color channel in the image.
It should be explained that, since the color image acquired by the industrial camera is typically an RGB image, the RGB color space describes colors with R, G, B three components that respectively describe the proportion of red, green, and blue in one color. The brightness value of the three components is in the range of 0-255, and the larger the value is, the higher the proportion of the color component in the pixel point is. For example, the marker adopts blue of one of three primary colors, and after the collected color image is split into three gray images of three channels of red, green and blue, the image background only contains white and skin color, and the target is blue. The red component and the blue component in white are the same, the skin colors of different people are mainly brightness differences, the chromaticity difference of the skin colors is not large, the red component is larger than the blue component, and the blue component of the blue marker is far larger than the red component. Therefore, in the gray level image of the blue channel, the brightness value of the marker is obviously higher, so that the background variegated can be removed by subtracting the gray level value of the pixel corresponding to the red channel and the gray level value of the pixel corresponding to the green channel from the gray level value of the pixel corresponding to the blue channel in the color image. Compared with the common target segmentation in HSV color space, the method fully utilizes the color characteristics of the background in the radiotherapy monitoring range, omits the step of color space conversion, and does not need to consider the selection of the thresholds of each component under different illumination conditions.
And obtaining a gray image which only contains the marker after the background is removed. Fitting the positioning markers requires points on the outer contours of the markers, and therefore, after isolating the markers, the points on the outer contours of the markers need to be extracted. Specifically, the step S22 specifically includes the following steps:
Step SA1121: : calculating the outline of the gray level map containing the markers by using a Canny algorithm;
step SA1122: removing contours with areas smaller than a set threshold value from the contours;
step SA1123: and (3) calculating convex hulls for all the outlines of each marker, and calculating to obtain the outline of each marker.
Noise points in the marker segmented image may be removed via step SA 1122. The contour obtained at this time is not the contour of the outermost layer of the marker, but a plurality of small contours formed after the markers are blocked by the thermoplastic film, a convex hull needs to be obtained for all the contours of each marker, in step SA1123, a Graham scanning algorithm is used to obtain the convex hull of the contour of the marker, and the top point of the convex hull is the point on the outer contour of the marker. The time consumption of the Graham scanning algorithm is positively correlated with the number N of the contour points, and the larger the N is, the longer the time consumption of the algorithm is, so that the time consumption of the algorithm can be reduced by designing the marker into a ring, and the real-time performance is better ensured.
Since the positioning of the marker only requires the outer contour information of the marker, in order to reduce the amount of computation when positioning the marker, the information of the middle part of the marker is omitted in another embodiment of the present invention. Extracting the outline of the marker, obtaining the shape of the marker by adopting a fitting algorithm, determining the geometric center position of the marker, and positioning the marker to obtain the position of the tumor target area.
Illustratively, in this embodiment, the marker is a circular ring marker, and the circular ring marker has a ring width not smaller than a shielding portion between the thermoplastic film small holes. For example, as shown in fig. 6, the width of the shielding part between the small holes of the common medical thermoplastic film is 2mm, the ring width of the circular ring markers can be set to be 3mm, so that part of the markers are always leaked, the failure of positioning the markers caused by shielding the markers is avoided, and the circular ring markers are arranged in a matrix of 90mm x 90 mm. The circular ring marker is exemplified by a circular ring with the diameter of 3mm, the position of the circle can be determined by knowing three points on the circle according to mathematical knowledge, namely, the position of the marker can be positioned by only finding the three points on the marker on the thermoplastic film. Compared with the rectangular marker, the four sides are required to be positioned to position the specific position of the marker, so that fewer points need to be positioned, and the position of the marker is positioned more. As can be seen from fig. 7a, 7b and 7c, the markers at the X corner points cannot be positioned by the thermoplastic film, and when two parallel sides of the rectangle are blocked, the rectangles at three different positions in the figure have the same exposed contour, i.e. the unique rectangular markers cannot be restored by the outer contour of the rectangle, and thus cannot be positioned accurately. Only a circular (or ring) marker can determine a uniquely determined circle by only three points, so designing the marker into a circular (or ring) can minimize the influence of thermoplastic film shielding on marker positioning. Note that, in fig. 7a, 7b and 7c, the solid circles are ventilation holes of the thermoplastic film, and the dotted lines represent the outline of the markers under the thermoplastic film.
In another embodiment of the present disclosure, the step of locating the marker comprises:
SA101, extracting feature points on the physical feature markers;
SA102, matching the displacement of the characteristic points in the real-time image and the reference image by adopting a characteristic point matching algorithm, and positioning the marker.
Specifically, the markers have obvious physical characteristics, and feature points on the markers are extracted when the markers are positioned. The method comprises the steps of extracting feature points of a marker by a Harris corner detection algorithm, matching the feature points in a real-time image and a reference image by a feature point matching algorithm after the feature points are extracted, and calculating displacement of the feature points, so that the marker is positioned. For example, a feature point a exists on the marker, and the feature point a is located on a specific portion of the marker. When the feature point A is monitored, the shape of the marker is known, the displacement through the feature point A is the displacement of the marker, and the marker can be positioned according to the displacement of the marker.
In another embodiment of the present invention, a geometric center position of a marker is disclosed, and the specific steps of positioning the marker are specifically shown in fig. 3:
Step SA1131: extracting points on the outer contour of the marker;
step SA1132: fitting an ellipse by adopting a least square method;
Step SA1133: calculating the distance from all fitting points to the center of the fitted ellipse, and eliminating noise points with abnormal distance by adopting a Grabbs criterion;
Step SA1134: fitting the ellipse by adopting a least square method again;
step SA1135 judges whether or not the noise point is contained; if the noise point is included, the process goes back to step SA1133, and if the noise point is not present, the marker is positioned by the ellipse center.
Although the set marker is in a circular ring shape, the surface of the human body is three-dimensional, and the human body cannot be completely horizontal, so that the shot marker is closer to an elliptical ring, and therefore, the marker is fitted by adopting an ellipse in the invention. The principle of the standard least squares ellipse fitting algorithm is as follows: the general equation for an ellipse is shown in equation (1). Setting n points to be fitted in the image, wherein the coordinates of the ith point to be fitted are Pi (xi, yi), (i=0, 1,2, …, n), and enabling the square sum of distances from all points to be fitted to ellipses to be minimum, namely enabling the ellipse in the minimum value of the formula (2) to be the least square fitting result. And (3) taking the minimum value according to the extremum theory when the formula (3) is satisfied. Solving the linear equation set obtained in the formula (3) can obtain parameters A, B, C, D, E and F of a general equation for fitting the ellipse. The center coordinates (x center,ycenter) of the ellipse can be obtained from the parameters of the general equation of the ellipse by equation (4).
Ax2+Bxy+Cy2+Dx+Ey+F＝0 (1)
Preferably, in order to improve the accuracy and the real-time performance of the least square ellipse fitting algorithm for positioning the markers. Fitting the marker and acquiring the central position of the marker for positioning comprises the following steps:
Extracting points on the outer contour of the marker;
fitting an ellipse by adopting a least square method;
calculating the distance from all fitting points to the center of the fitting ellipse;
removing noise points with abnormal distances by adopting a Grabbs criterion;
Fitting an ellipse by adopting a least square method again, and judging whether noise points are contained or not; if the noise points are contained, jumping back to remove the noise points with abnormal distance by adopting the Grabbs criterion, and if the noise points do not exist, positioning the marker by using the ellipse center.
After contour screening, most of noise in the image is removed, but sometimes few extracted marker outline points are not on the marker outline, and the noise points cause the ellipse fitted by the traditional least square ellipse fitting algorithm to have larger deviation from the true ellipse, so that the ellipse needs to be re-fitted after the noise points are removed. Specifically, the median of the x-axis coordinates and the y-axis coordinates of all the points to be fitted is calculated, and the coordinates are taken as reference points. And calculating to obtain algebraic distance di (i=0, 1,2 …, n) between each point to be fitted and the reference point, regarding the group of data as a sample point set, removing coarse difference points in the sample according to the 90% confidence probability according to the Grabbs criterion, re-fitting the ellipse by using the rest sample points, checking whether the ellipse contains the coarse difference points, removing the coarse difference points until the coarse difference points are not found, and finally fitting the rest points to obtain the positioning result for the mark.
Preferably, since the displacement of the patient under the fixation of the thermoplastic film is limited, the markers are only present in a partial region of the image, so that step SA1135 is followed by step SA1136 to reduce unnecessary computation: and intercepting a rectangle which takes the fitted ellipse center as a center and has a length and a width which are preset times of the ellipse length and the short axis as a region of interest (ROI), wherein the image after the region of interest representation only carries out ellipse fitting in the region of interest.
And then, each frame of real-time image is subjected to ellipse fitting only in the ROI, so that unnecessary pixel points on the traversing image during image processing can be omitted, and compared with the condition that a coordinate system is established by the whole image, the coordinate value of the point to be fitted is obviously reduced, and the calculation speed of an ellipse fitting algorithm can be improved.
In another embodiment of the invention, a tumor target displacement monitoring device is also disclosed, and comprises an image acquisition unit, a marker and an image processing unit. The image acquisition unit is for acquiring an image, for example. For example, the image acquisition unit is an industrial camera, as shown in fig. 4, and in operation, the industrial camera 1 is fixed above the treatment couch 6 by means of the support 5, perpendicular to the part of the patient suffering from a tumor, the part is photographed, and then the image is transmitted to the image processing unit (not shown in the figure). The marker 2 is used for positioning the tumor position, is made of reflective materials, fixes the body surface of a patient, and is opposite to the position of the tumor, and used for marking the tumor target area, wherein the mark 3 is a patient model. The image processing unit analyzes and processes the received images to finally obtain the result of the tumor target displacement, and provides reference opinion for doctor treatment. Specifically, the image processing unit processes the image to perform the steps in any of the above-described method embodiments. Compared with the method for monitoring the displacement of the tumor target area in real time by adopting the metal marker through X-ray forming, the reflective marker adopted by the invention can not bring additional radiation and infection side effects to patients. Preferably, for facilitating the operation of a doctor, the device further comprises a display unit, and the display unit is connected with the image processing unit and used for displaying the displacement of the tumor target area in an image mode.
Because the light reflected by the marker can reach the camera after being blocked by the thermoplastic film, most of the light is blocked by the thermoplastic film, so that the marker has dark brightness and unobvious color characteristics in the captured image.
Further, in order to facilitate positioning of the marker, the surface of the marker is attached with a microprism type reflective film 21. An annular light source 4 with a small divergence angle is coaxially installed with the industrial camera, and the annular light source 4 vertically irradiates the marker. The microprism type reflecting film is a reflecting material prepared based on the refraction and total reflection principles of cube-corner prisms. As can be seen from fig. 5a and fig. 5b, after the light with a small angle emitted from the periphery of the camera irradiates the microprism structure, most of the light is reflected back to the camera, and compared with the markers made of common diffuse reflection materials, more light is reflected to the camera, so that the brightness of the markers in the image is improved, and the extraction and positioning are easy.
Exemplary, in one embodiment of the present invention, the main parameters of the device related device are as follows:
Table 1 hardware device and main parameters of the device
In another embodiment of the present invention, a computer readable storage medium is further disclosed, on which a computer program is stored, and after the computer program is executed, the tumor target displacement monitoring method described in any one of the above embodiments is executed.
In another embodiment of the present invention, a computer device is also disclosed, including a processor, a storage medium, where a computer program is stored, and the processor reads and executes the computer program from the storage medium to perform the tumor target displacement monitoring method described in any of the foregoing embodiments.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (7)

1. A method for monitoring displacement of a tumor target area is characterized in that,
The method comprises the following steps:
Step S1: setting a treatment point on the thermoplastic film, wherein the treatment point is a radiation position of radiotherapy; positioning the markers, wherein the positions of the markers correspond to the tumor target area, the markers are partially shielded by the thermoplastic film, and a small part of marker outlines are leaked from the ventilation holes on the thermoplastic film;
step S2: calculating a displacement value of the tumor target area according to the relative displacement value of the marker and the treatment point;
The marker is a geometric shape marker, and the color of the marker adopts one of three primary colors;
the step of locating the marker comprises:
SA111, dividing the marker from the background;
SA112, marking the outline of the marker by adopting a fitting algorithm;
SA113, determining the geometric center position of a marker, and positioning the marker;
step SA111 specifically includes the steps of:
SA1111, splitting the collected color image into three gray scale images of red, green and blue channels respectively;
SA1112, subtracting the gray value of the pixel corresponding to the color channel of the marker from the gray value of the pixel corresponding to the color channel of the marker in the image;
step SA112 specifically includes:
SA1121: calculating the outline of the gray level map containing the markers by using a Canny algorithm;
SA1122: removing contours with areas smaller than a set threshold value from the contours;
SA1123: and (3) calculating convex hulls for all the outlines of each marker, and calculating to obtain the outline of each marker.
2. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The step of locating the marker comprises:
SA101, extracting feature points on the physical feature markers;
SA102, matching the displacement of the characteristic points in the real-time image and the reference image by adopting a characteristic point matching algorithm, and positioning the marker.
3. The method of claim 1, wherein the step of determining the position of the substrate comprises,
Step SA113 specifically includes the steps of:
SA1131: extracting points on the outer contour of the marker;
SA1132: fitting an ellipse by adopting a least square method;
SA1133: calculating the distance from all fitting points to the center of the fitted ellipse, and eliminating noise points with abnormal distance by adopting a Grabbs criterion;
SA1134: fitting the ellipse by adopting a least square method again;
SA1135: judging whether noise points are contained or not; if the noise point is included, the process goes back to step SA1133, and if the noise point is not present, the marker is positioned by the ellipse center.
4. The method of claim 3, wherein the step of,
The method further comprises step SA1136: and taking the center of the ellipse as the center, taking a rectangular area with the length and the width of a preset multiple of the ellipse axis as an interested area of the next frame of image, wherein the image after the interested area representation only carries out ellipse fitting in the interested area.
5. A tumor target displacement monitoring apparatus using the method according to any one of claims 1 to 4, characterized in that,
The apparatus comprises:
an image acquisition unit for acquiring an image, wherein the image acquisition unit coaxially mounts an annular light source of small divergence angle and disposes with the marker;
A marker for locating a tumor position, wherein a microprism type reflective film is attached to the surface of the marker;
and the image processing unit is used for processing and calculating the image to obtain tumor target area displacement information.
6. A computer readable storage medium, wherein a computer program is stored on the medium, and the computer program is executed to perform the tumor target displacement monitoring method according to any one of claims 1 to 4.
7. A computer device comprising a processor, a storage medium having a computer program stored thereon, the processor reading from the storage medium and running the computer program to perform the tumor target displacement monitoring method of any one of claims 1 to 4.
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