CN108320328B

CN108320328B - Particle counting device for interaction of 2D image and 3D image

Info

Publication number: CN108320328B
Application number: CN201810137032.4A
Authority: CN
Inventors: 柏朋刚; 戴艺涛; 陈济鸿; 陈传本
Original assignee: Fujian Tumour Hospital (fujian Tumour Institute Fujian Cancer Control And Prevention Center)
Current assignee: Fujian Tumour Hospital (fujian Tumour Institute Fujian Cancer Control And Prevention Center)
Priority date: 2018-02-10
Filing date: 2018-02-10
Publication date: 2021-07-30
Anticipated expiration: 2038-02-10
Also published as: CN108320328A

Abstract

The invention relates to a particle counting method for interaction of a 2D image and a 3D image, which comprises the steps of obtaining a CT (computed tomography) image of a patient after the implantation of particles and a corresponding tumor region of the patient, and obtaining the 2D image; adjusting a reconstruction threshold of the set 3D model, extracting the outer contour of the particles, and establishing the 3D model according to the outer contour; taking the position of the selected particle in the 2D image as the center of the particle in the 3D model, and establishing a coordinate system; displaying the layer position of the 2D layer in the 3D model, and determining the position of the center of the particle according to the interactive relation between the layer position and the layer position; and counting the number of the implanted particles according to the determined central position, and further acquiring the number of the implanted particles. The invention provides a 2D image and 3D image interactive particle counting method which is applied to image-guided particle implantation radiotherapy so as to improve the accuracy of dose evaluation of particle implantation.

Description

Particle counting device for interaction of 2D image and 3D image

Technical Field

The invention relates to the technical field of medical image processing and image-guided radiotherapy, in particular to a particle counting device with interaction of a 2D image and a 3D image.

Background

There are three main tumor treatment approaches: surgery, radiation therapy and chemotherapy. As living conditions increase, more and more tumors are discovered at an early stage and treated. The radiation therapy has a unique position in the tumor therapy. The curative effect of the radiation therapy of tumors such as nasopharyngeal carcinoma, cervical carcinoma, breast cancer, prostatic cancer and the like is not replaced by other treatment modes, and the effect of the radiation therapy is almost the same as that of other treatment modes. Over 60% of patients in current treatments require full or partial radiation therapy. The basic goal in radiotherapy is to try to improve the gain ratio of radiotherapy, and to give sufficient irradiation dose to the tumor region while surrounding normal tissues and organs are irradiated as little as possible or are protected from unnecessary irradiation, thereby avoiding other complications caused by radiotherapy.

In radiotherapy, there are mainly external irradiation and close-range internal irradiation. With the new century, external irradiation technology has been rapidly developed under the development of computer technology, such as IMRT, VMAT, IGRT technology, and the like. However, irradiation of radiotherapy at close range is also one of the irreplaceable techniques. The implantation of seeds is an effective means of brachytherapy that can adequately irradiate the tumor area, but can well protect normal organs. Over 20 years, particle therapy has been rapidly developed in China, and although there is a treatment planning system and image-guided particle implantation is performed under a simulator or a CT machine, how to accurately evaluate the dose distribution of the brachytherapy of the particles after the particles are implanted into the body of a patient is a problem which is difficult to solve at present. There are two major difficulties with online particle implantation: first, the exact location of the particles and the number of particles are difficult to determine. Secondly, since the determination of the center point of the particle based on the 2D image requires many times of human subjective judgments, it takes a long time and the accuracy of the position of the particle cannot be guaranteed. Therefore, when the online particles are implanted, the time required for determining the positions and the number of the particles is too long, so that the optimal time for supplementing the particles for the patient is missed, and the treatment effect of the patient can be seriously affected.

With the development of medical imaging technology, the three-dimensional image reconstruction technology plays an increasingly important role in image-guided radiotherapy. The three-dimensional model is utilized to guide the operation, and plays an important role in the current operation navigation. In on-line and off-line evaluation of particle implantation, the inability of a physician to accurately and quickly determine the precise location of the particles can produce fatal errors for the efficacy evaluation of the treatment due to technical and time constraints. Therefore, how to accurately and quickly determine the spatial position of the particles according to the imaging positions of the particles in the online acquired two-dimensional image further improves the accuracy of dose assessment of the patient, and finally improves the treatment effect of the patient is a difficult problem in front of doctors and physicists.

Disclosure of Invention

The invention aims to provide a particle counting device for interaction of a 2D image and a 3D image, so as to overcome the defects in the prior art.

In order to achieve the purpose, the technical scheme of the invention is as follows: a particle counting device for interaction of a 2D image and a 3D image is realized according to the following steps:

step S1: acquiring a CT image of a patient after the implantation of the particles and a tumor region corresponding to the CT image, and acquiring a 2D image;

step S2: selecting the range of the particles in the 2D image, adjusting and setting a reconstruction threshold of a 3D model, extracting the outer contour of the particles, and establishing the 3D model according to the outer contour;

step S3: taking the position of the selected particle in the 2D image as the center of the particle in the 3D model, and establishing a coordinate system; displaying the section position of the 2D layer in the 3D model, and determining the position of the center of the particle according to the interactive judgment between the section position and the section position;

step S4: according to the step S3, the number of implanted particles is counted according to the determined central position, and the total number of implanted particles is obtained.

In an embodiment of the present invention, in the step S1, the method further includes the following steps: the patient carries out the implantation of the particles through image guidance, and after the implantation of the particles, the implantation region of the particles is scanned by adopting the CT layer thickness of 2.5mm, the corresponding tumor region is sketched out, and an image with the layer thickness of 2.5mm is transmitted and reconstructed on a CT machine.

In one embodiment of the invention, the patient adopts a supine position, holds his head with both hands or lifts his single arm, and performs CT scanning; philips large aperture helical positioning CT scan was performed over a range including: scanning the extension of each head and foot of the tumor by at least 2 cm; scanning conditions are as follows: the image pitch is equal to 2.5mm and the layer thickness is 2.5 mm.

In an embodiment of the present invention, in the step S2, the method further includes the following steps:

step S21: selecting a reconstruction range; selecting a reconstruction region including left, right, front, back, head and feet of a tumor on the 2D image; amplifying the 2D image, and generating a new local 2D image by adopting bicubic interpolation processing operation among pixels;

step S22: selecting a particle 3D threshold; according to a 3D model reconstruction threshold value set in the local 2D image, eliminating other tissues of which the HU value is smaller than a particle boundary value, and generating a 2D sequence image only comprising the particles;

step S23: generating a 3D model; according to the 2D sequence images, synthesizing an image sequence to generate a 3D model sequence; performing image extraction to reduce the data volume displayed by the 3D model sequence; smoothing the data of the 3D model sequence through a smoothing function to obtain smoothed data; generating a 3D model patch to obtain a 3D model;

step S24: 3D model display settings; and adjusting the color of the 3D model to be red, setting the transparency of the 3D model, and setting the unit of the background color of the window to be black.

In an embodiment of the present invention, in the step S3, the method further includes the following steps:

step S31: rotating the angle of the 3D model to display all the particles, marking two particles connected with the head and the feet as one particle, and carrying out preliminary statistics on the number of the particles;

step S32: for two particles connecting the head and the feet, according to the brightness in the 2D image, taking a bright point as the center of the corresponding selected particle, establishing a coordinate axis in a 3D model according to the center, and virtually displaying the bright point according to planes of two axes vertical to the head and the feet of the patient; if the center of the selected particle is located at the edge part of the particle in the 3D model, discarding the point; if the particle is positioned at the center point of the particle in the 3D model, marking the particle as the position center of the particle, and marking the particle in the 3D model;

step S33: when a particle is added to the particle statistical list, the serial number of the particle and the spatial coordinate position of the center of the particle are recorded, or the serial number and the spatial coordinate position are interactively determined at the center point of the particle; generating a virtual particle according to the center of the selected particle; checking whether the position of the virtual particle is contained in the particle position of the 3D model; rotating a coordinate axis based on the head and foot directions of the virtual particles, matching with the 3D model, and judging the central position of the particles;

step S34: and judging the final position of the particle according to the adhesion condition of the particle.

Compared with the prior art, the invention has the following beneficial effects: the invention introduces interactive space position judgment in the field of image-guided radiotherapy by fully utilizing the advantages of modern medical imaging and medical image processing technology, and establishes a 3D model based on the outer contour of the particle segmented by the 2D image. The positions in the 2D image are mapped to a 3D model space coordinate system, so that the space positions of the particles and the quantity of the implanted particles are judged quickly and accurately, the irradiated dose of the tumor is evaluated accurately, and the implantation of the particles on site is guided. Provides powerful technical support for judging the irradiated dose of the tumor on site and whether the implantation quantity and the implantation position need to be increased, and improves the effect of tumor radiotherapy.

Drawings

Fig. 1 is a path diagram of a particle counting method for interaction between a 2D image and a 3D image according to the present invention.

FIG. 2 is a 3D model of particle contours extracted from a selected range of 2D images according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of positions of particles selected in a 2D image according to an embodiment of the invention.

Fig. 4 is a coordinate axis diagram of a 3D display corresponding to a 2D position according to an embodiment of the invention.

Fig. 5 is a corresponding layer diagram of a 3D display 2D image according to an embodiment of the invention.

FIG. 6 is a diagram of particle labeling and position determination in accordance with an embodiment of the present invention.

Detailed Description

The technical scheme of the invention is specifically explained below with reference to the accompanying drawings.

The invention provides a particle counting device for interaction of a 2D image and a 3D image, which is realized according to the following steps as shown in figure 1:

step S2: selecting the range of the particles in the 2D image, adjusting and setting the reconstruction threshold of the 3D model, extracting the outer contour of the particles, and establishing the 3D model according to the outer contour;

step S4: according to step S3, the number of implanted particles is counted according to the determined center position, and the total number of implanted particles is obtained.

In this embodiment, in step S1, the method further includes the following steps: the patient carries out the implantation of the particles through image guidance, and after the implantation of the particles, the implantation region of the particles is scanned by adopting the CT layer thickness of 2.5mm, the corresponding tumor region is sketched out, and the image with the layer thickness of 2.5mm is transmitted and reconstructed on a CT machine, so that the region where the particles are positioned is clearly checked.

In this embodiment, the patient adopts the supine position, and both hands embrace the head or lift the single arm, carry out Philips large aperture spiral positioning CT scan, and the scanning range includes: scanning the extension of each head and foot of the tumor by 2cm at least, and determining according to the specific condition of a patient; scanning conditions are as follows: the image pitch is equal to 2.5mm and the layer thickness is 2.5 mm. According to International Commission on Radiation Units and Measurements (ICRU) 50 and 83 documents [ 1-2 ], the test materials are determined according to the corresponding examination materials: the MRI, PET/CT images delineate the tumor region in the localized CT image, and the GTV is acquired.

In this embodiment, as shown in fig. 2, in step S2, the method further includes the following steps:

step S21: selecting a reconstruction range; selecting a reconstruction region including left, right, front, back, head and feet of the tumor on the 2D image; amplifying the 2D image by 8 times, and generating a new local 2D image by adopting bicubic interpolation processing operation among pixels;

bi-cubic interpolation is used for taking a 4x4 neighborhood point (x) near a pixel point (x, y) to be interpolated (x and y can be floating point numbers)_i,y_j),iJ is 0, 1, 2, 3. The interpolation is performed according to the following formula:

step S22: selecting a particle 3D threshold; displaying the set 3D model reconstruction threshold in the local 2D image, determining the threshold by taking the HU value of the particles at the edge displayed by the CT image, eliminating other tissues of which the HU value of the CT image is smaller than the boundary value of the particles, and generating a 2D sequence image only comprising the particles;

step S23: generating a 3D model; performing image serialization synthesis according to the 2D sequence images to generate a 3D model sequence; performing image extraction to reduce the data volume displayed by the 3D model sequence; smoothing the data of the 3D model sequence through a smoothing function to obtain smoothed data; generating a 3D model patch to obtain a 3D model;

In this embodiment, to realize the interactive determination of the accurate position of the particle, the most important thing is to select a position in the two-dimensional image, and then display the spatial position of the particle in the 3D model by using coordinate axes, and simultaneously display the position of the 2D image in the 3D model, so as to determine whether the position is the center of the particle, thereby determining the center point of the dose calculation with the position. However, since the orientation and position of the particles may be changed greatly after the particles are implanted into the body, some particles may be displayed separately. Many particles are connected together due to deformation and compression of the tissue, etc. In this embodiment, the spatial position of the center point of the particle can be rapidly determined through the interaction between the 2D image and the 3D model through the auxiliary 3D model. In order to further improve the accuracy of the particles, a virtual particle is generated by using a set point as a target, and whether the central point is the central point of the particle is judged through the virtual particle.

In this embodiment, in step S3, as shown in fig. 3 to 6, the method further includes the following steps:

step S31: and rotating the angle of the 3D model to display all the particles, wherein the specific rotation angle is specifically determined according to the actual situation. Recording two particles connected with the head and the feet as one particle, and carrying out preliminary statistics on the number of the particles; in this embodiment, counting is performed with visually distinct individual particles.

Step S32: for two particles connecting the head and the feet, according to the brightness in the 2D image, taking a bright point as the center of the corresponding selected particle, and establishing a coordinate axis in the 3D model according to the center, wherein three primary coordinate axes are respectively the head and the feet of the patient; left and right, front and back; and virtually displaying according to planes of two axes which are vertical to the head and foot directions of the patient; if the center of the particle selected from the 2D image is located at the edge part of the particle in the 3D model, discarding the point; if the point is positioned at the center point of the particle in the 3D model, marking the point as the position center of the particle, and marking the point in the 3D model;

step S33: when a particle is added to the particle statistical list, the serial number of the particle and the spatial coordinate position of the center of the particle are recorded, and the serial number and the spatial coordinate position can also be interactively determined at the center point of the particle; according to the specific size of the particles provided by the manufacturer, a virtual particle model is generated by taking the center of the selected particles as the center. Checking whether the position of the virtual particle is contained in the particle position of the 3D model; when the virtual particle is used, the initial state of the virtual particle is the head and foot direction which can be preliminarily taken as the standard, at the moment, the coordinate axis assisted by the virtual particle can be rotated, and then the matching with the 3D model is carried out to judge the central position of the particle;

step S34: and judging the final position of the particle according to the adhesion condition of the particle. The method of generating the virtual particle is used to repeatedly test and determine the actual accurate position of the particle.

The above are preferred embodiments of the present invention, and all changes made according to the technical scheme of the present invention that produce functional effects do not exceed the scope of the technical scheme of the present invention belong to the protection scope of the present invention.

Claims

1. A particle counting apparatus for interaction of 2D images and 3D images, the apparatus implementing the steps of:

step S4: according to the step S3, counting the number of implanted particles according to the determined central position, thereby obtaining the total number of implanted particles;

in step S3, the method further includes the steps of:

2. A particle counting device for 2D image and 3D image interaction according to claim 1, wherein in step S1, the method further comprises the following steps: the patient carries out the implantation of the particles through image guidance, and after the implantation of the particles, the implantation region of the particles is scanned by adopting the CT layer thickness of 2.5mm, the corresponding tumor region is sketched out, and an image with the layer thickness of 2.5mm is transmitted and reconstructed on a CT machine.

3. The apparatus according to claim 2, wherein the patient is in a supine position, held with two hands or lifted with one arm, and CT-scanned; philips large aperture helical positioning CT scan was performed over a range including: scanning the extension of each tumor head and foot direction by 2cm at least; scanning conditions are as follows: the image pitch is equal to 2.5mm and the layer thickness is 2.5 mm.

4. A particle counting device for 2D image and 3D image interaction according to claim 1, wherein in step S2, the method further comprises the following steps: