CN117665894A - Proton imaging method and apparatus - Google Patents
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Abstract
The present disclosure provides a proton imaging method and apparatus, the proton imaging method comprising: generating a proton beam by using a proton accelerator, and transmitting the proton beam to a scintillator; in the process that the proton beam reaches the scintillator, the beam spot size and the proton number of the proton beam are adjusted by using a collimator, so that the adjusted proton beam is obtained; when the adjusted proton beam does not pass through the imaging object, controlling a camera device to shoot the range of the proton beam in the scintillator by using proton imaging equipment to obtain an initial range photo; when the adjusted proton beam passes through an imaging object, the proton imaging equipment is used for controlling a camera device to shoot the residual range of the adjusted proton beam in the scintillator, and the angle and the position of a displacement table are adjusted by the proton imaging equipment to obtain a plurality of residual range image data; and processing the initial range image and the plurality of residual range image data by using a proton imaging device and reconstructing the images to obtain a relative stopping power distribution image of the imaged object.
Description
Technical Field
The present disclosure relates to the field of particle radiography, and in particular to a proton radiography method and apparatus.
Background
Current proton imaging systems fall into two main categories: single Proton tracking systems (Proton-tracking systems) based on single Proton detection and Proton integrated systems (Proton-integrating system) based on Proton beam detection. Single proton tracking systems typically comprise 4 position sensitive detectors and 1 residual energy detector, and image reconstruction is performed by the position and energy of a single proton, which has the disadvantage of complex structure and the need for a high-speed data acquisition system to acquire the position and energy of a single proton. The proton integrated system only comprises one residual energy detector (such as a multi-layer ionization chamber detector, a flat panel detector and the like), and has the defects that the spatial resolution of a reconstructed image is influenced by the beam spot size of a proton beam, the improvement is difficult, and the imaging dosage of the method is large.
Disclosure of Invention
In view of the above, the present disclosure provides proton imaging methods and apparatus.
According to a first aspect of the present disclosure, a proton imaging method, comprises:
generating a proton beam by using a proton accelerator, and transmitting the proton beam to a scintillator;
in the process that the proton beam reaches the scintillator, the beam spot size and the proton number of the proton beam are adjusted by using a collimator, so that the adjusted proton beam is obtained;
When the adjusted proton beam does not pass through the imaging object, the proton imaging equipment is used for controlling the camera device to shoot the initial range of the adjusted proton beam in the scintillator, so as to obtain initial range image data;
when the adjusted proton beam passes through the imaging object, the adjusted proton beam passes through the imaging object and then enters the scintillator, the proton imaging equipment is used for controlling the camera device to shoot the residual range of the adjusted proton beam in the scintillator, and the angle and the position of the displacement table are adjusted by the proton imaging equipment, so that a plurality of residual range image data of the adjusted proton beam passing through different positions and different angles of the imaging object are obtained, wherein the imaging object is placed on the displacement table;
processing the range image data by using proton imaging equipment to obtain a water equivalent range, wherein the range image data comprises initial range image data and a plurality of residual range image data, and the water equivalent range comprises initial water equivalent range and a plurality of residual water equivalent ranges;
obtaining a plurality of water equivalent lengths of the imaging object based on the water equivalent range, including an initial water equivalent range and a plurality of remaining water equivalent ranges;
and performing image reconstruction based on a plurality of water equivalent lengths to obtain a relative stopping power distribution image of the imaging object.
According to an embodiment of the present disclosure, before obtaining the initial range image, the method further includes:
and shooting the scintillator by using a camera device under the shading condition to obtain background image data.
According to an embodiment of the present disclosure, a proton imaging device is used to control a camera device to capture a residual range of an adjusted proton beam in a scintillator, and an angle and a position of a displacement table are adjusted by the proton imaging device, so as to obtain a plurality of residual range image data when the adjusted proton beam passes through different positions and different angles of an imaging object, including:
the proton imaging equipment controls the displacement platform to translate or rotate after the last shooting of the camera device is finished;
the proton imaging equipment controls the camera device to shoot the adjusted proton beam to pass through the residual range of the imaging object in the scintillator, and a plurality of residual range image data of the adjusted proton beam when passing through different positions and different angles of the imaging object are obtained.
According to an embodiment of the present disclosure, processing range image data with a proton imaging device to obtain a water equivalent range, wherein the range image data includes initial range image data and a plurality of remaining range image data, the water equivalent range includes initial water equivalent range and a plurality of remaining water equivalent ranges, including:
Respectively carrying out image processing on the initial range image data and the plurality of residual range image data for a plurality of times based on the background image data to obtain a plurality of light ranges;
and respectively performing calibration treatment on the light ranges to obtain a plurality of water equivalent ranges.
According to an embodiment of the present disclosure, performing image processing on initial range image data and a plurality of remaining range image data, respectively, a plurality of times based on background image data to obtain a plurality of light ranges, includes:
respectively performing background removal processing on the initial range image data and the plurality of residual range image data based on the background image data to obtain a plurality of first image data;
respectively carrying out distortion correction processing on the plurality of first image data to obtain a plurality of second image data;
respectively carrying out noise reduction processing on the plurality of second image data to obtain a plurality of third image data;
respectively obtaining a plurality of depth light intensity distribution curves according to the light intensity signals in the plurality of third image data;
and obtaining a plurality of light ranges according to the plurality of depth light intensity distribution curves respectively.
According to an embodiment of the present disclosure, calibration processing is performed on a plurality of light ranges, respectively, to obtain a plurality of water equivalent ranges, including:
Respectively carrying out linear calibration on the plurality of light ranges to obtain a plurality of calibrated light ranges;
and multiplying the plurality of calibrated light ranges by the relative stopping power value of the scintillator to obtain a plurality of water equivalent ranges, wherein the relative stopping power value of the scintillator is calculated by the element composition of the scintillator, the mass fraction of each element and the average ionization energy of each element by using the Bragg additivity rule.
According to an embodiment of the present disclosure, wherein obtaining a plurality of water equivalent lengths of an imaged object based on a water equivalent range, including an initial water equivalent range and a plurality of remaining water equivalent ranges, includes:
the water equivalent length is determined by the following formula:
WEPL＝R W0 -R W1 ；
wherein WEPL denotes the water equivalent length of the imaged object, R W0 Represents the initial water equivalent range, R W1 Indicating the equivalent range of the remaining water.
According to an embodiment of the present disclosure, wherein image reconstruction is performed based on a plurality of water equivalent lengths to obtain a relative stopping power distribution image of an imaged object, comprising:
image reconstruction is carried out along the path direction of the proton beam by utilizing the relation between the water equivalent length and the relative blocking capacity of the imaging object to obtain a relative blocking capacity distribution image of the imaging object, wherein the relation between the water equivalent length of the imaging object and the relative blocking capacity of the imaging object is determined by the following formula:
WEPL＝∫RSP(x,y)dl；
Where WEPL represents the water equivalent length of the imaged object, RSP (x, y) represents the relative stopping power value at the (x, y) position on the relative stopping power distribution image, dl represents the increment per unit length along the proton beam flow path.
According to an embodiment of the present disclosure, wherein adjusting the displacement stage with the proton imaging apparatus comprises:
responding to the on and off of the proton accelerator, collecting an on signal and an off signal sent by the proton accelerator by the proton imaging equipment, and controlling a camera device to shoot between the on and off of the proton accelerator in an external trigger mode;
after the camera device shoots, the proton imaging apparatus adjusts the angle and position of the displacement stage.
A second aspect of the present disclosure provides a proton imaging apparatus, comprising:
a proton accelerator for generating a proton beam and emitting the proton beam to the scintillator;
the collimator is used for adjusting the beam spot size and the proton number of the proton beam;
the displacement platform is used for placing an imaging object and has the functions of rotation and translation;
a scintillator for depositing energy of the proton beam and generating visible light along a proton path;
camera means for acquiring range image data of the proton beam incident on the scintillator;
The proton imaging equipment is used for controlling the camera device to acquire range image data, adjusting the angle and the position of the displacement table, processing the range image data to obtain a plurality of water equivalent ranges, reconstructing an image based on the water equivalent ranges, and obtaining a relative stopping power distribution image of an imaged object.
According to the embodiment of the disclosure, the proton beam is generated through the proton accelerator, and is emitted to the scintillator, and the beam spot size and the proton number of the proton beam are adjusted by the collimator in the process that the proton beam reaches the scintillator, so that the imaging spatial resolution is improved, and the proton imaging dosage is reduced. The proton beam after collimator adjustment passes through the imaging object and then enters the scintillator, the camera device is controlled by the proton imaging equipment to shoot the scintillator, the range of the proton beam after adjustment in the scintillator can be obtained, the high-speed data acquisition system is not required to acquire the position information and the energy information of each proton, and meanwhile, the development of a complex data processing algorithm is avoided, so that the research and development cost of the proton imaging system is reduced. The proton beam is deposited through the scintillator, the energy of the proton beam is converted into visible light, the range of the proton beam in the scintillator is obtained, and the detection efficiency and the detection sensitivity of the proton beam energy are improved. And shooting the scintillator through a camera device to obtain a plurality of pieces of residual range image data, and processing the plurality of pieces of residual range image data by utilizing a proton imaging device to obtain a relative stopping power distribution image of an imaged object.
Drawings
The foregoing and other objects, features and advantages of the disclosure will be more apparent from the following description of embodiments of the disclosure with reference to the accompanying drawings, in which:
FIG. 1 schematically illustrates a flow chart of a proton imaging method according to an embodiment of the present disclosure;
FIG. 2 schematically illustrates a flow chart for obtaining multiple light ranges in accordance with an embodiment of the present disclosure;
FIG. 3 schematically illustrates a flow chart for adjusting a displacement stage with a proton imaging apparatus in accordance with an embodiment of the present disclosure;
fig. 4 schematically illustrates a schematic diagram of a proton imaging apparatus according to an embodiment of the present disclosure;
FIGS. 5 (a), 5 (b) and 5 (c) are schematic diagrams schematically illustrating range image data without a collimator, range image data with a collimator and range image data through an imaged object, respectively, according to embodiments of the present disclosure; and
fig. 6 (a), 6 (b) schematically show a schematic diagram of an imaged object and a relative blocking power profile of the imaged object, respectively, according to an embodiment of the present disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expressions should generally be interpreted in accordance with the meaning as commonly understood by those skilled in the art (e.g.," a system having at least one of A, B and C "shall include, but not be limited to, a system having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
In the technical scheme of the invention, the related user information (including but not limited to user personal information, user image information, user equipment information, such as position information and the like) and data (including but not limited to data for analysis, stored data, displayed data and the like) are information and data authorized by a user or fully authorized by all parties, and the processing of the related data such as collection, storage, use, processing, transmission, provision, disclosure, application and the like are all conducted according to the related laws and regulations and standards of related countries and regions, necessary security measures are adopted, no prejudice to the public welfare is provided, and corresponding operation inlets are provided for the user to select authorization or rejection.
Embodiments of the present disclosure provide a proton imaging method that utilizes a proton accelerator to generate a proton beam and emits the proton beam to a scintillator; in the process that the proton beam reaches the scintillator, the collimator is utilized to adjust the proton number of the proton beam, so as to obtain the adjusted proton beam; the adjusted proton beam passes through an imaging object and is incident to a scintillator, wherein the imaging object is placed on a displacement table; controlling a camera device to shoot the range of the adjusted proton beam in the scintillator by using a proton imaging device, and adjusting the angle and the position of a displacement table by using the proton imaging device to obtain a plurality of residual range image data; respectively processing the plurality of residual range image data by using proton imaging equipment to obtain a plurality of water equivalent ranges; and (3) reconstructing an image based on a plurality of water equivalent ranges to obtain a relative stopping power distribution image of the imaging object.
Fig. 1 schematically illustrates a flow chart of a proton imaging method according to an embodiment of the present disclosure.
As shown in fig. 1, proton imaging of this embodiment includes operations S101 to S107.
In operation S101, a proton beam is generated using a proton accelerator, and emitted toward a scintillator.
According to an embodiment of the present disclosure, the proton beam current refers to a proton beam having a predetermined energy and a predetermined intensity.
According to an embodiment of the present disclosure, a proton accelerator is a device that accelerates protons to a predetermined energy to generate a proton beam. The proton accelerator may be a linear accelerator or a cyclotron.
According to an embodiment of the present disclosure, a proton accelerator is turned on, and parameters of the proton accelerator are adjusted so that a proton beam generated by the proton accelerator flows into and strikes a scintillator.
In operation S102, in the process that the proton beam reaches the scintillator, the beam spot size and the proton number of the proton beam are adjusted by using the collimator, and the adjusted proton beam is obtained.
According to an embodiment of the present disclosure, a scintillator is used to deposit energy of a proton beam and emit visible light along a path direction of the proton beam. The distribution of visible light emitted by the scintillator is related to the dose distribution of proton beam in the scintillator, and the scintillator can be a plastic scintillator with the advantages of easy processing, stable performance, short luminescence decay time, small light decay coefficient and low price.
According to an embodiment of the present disclosure, the collimator is a device made of metal having a through hole of a specific geometry for reducing the flux of the proton beam and adjusting the size of the proton beam to a predetermined value. Wherein the metal may be brass and the geometry may be circular with a predetermined diameter.
According to the embodiment of the disclosure, when the proton beam passes through the collimator, the collimator blocks and absorbs the proton beam deviated from the incident direction, and adjusts the shape of the proton beam to be the same as the geometry of the collimator, resulting in an adjusted proton beam.
In operation S103, when the adjusted proton beam does not pass through the imaging object, the proton imaging device is used to control the camera device to capture the initial range of the adjusted proton beam in the scintillator, so as to obtain initial range image data.
According to an embodiment of the present disclosure, the imaging object is an object set according to the need.
According to an embodiment of the present disclosure, the adjusted proton beam is directly incident to the scintillator when not passing through the imaging object, and the scintillator generates visible light along an incident path of the proton beam.
According to the embodiment of the disclosure, the proton imaging device is connected with the camera device through a connecting wire of the camera device, and receives range image data shot by the camera device. The camera device can be a scientific-grade complementary metal Oxide Semiconductor (sCMOS) camera, and can be externally triggered and controlled by a voltage pulse signal sent by the proton accelerator. For example, a voltage pulse signal sent by the proton accelerator during on and off is acquired, and is transmitted to the camera by using a connecting wire to perform external trigger control on the camera, so that the sCMOS camera is continuously exposed between an on signal and an off signal.
According to the embodiment of the disclosure, the proton imaging device controls the camera device to shoot the initial range of the adjusted proton beam in the scintillator, so as to obtain initial range image data, wherein the initial range image data only needs to be shot once.
In operation S104, when the adjusted proton beam passes through the imaging object, the adjusted proton beam enters the scintillator after passing through the imaging object, the proton imaging device is used to control the camera device to shoot the remaining range of the adjusted proton beam in the scintillator, and the angle and the position of the displacement table are adjusted by the proton imaging device, so as to obtain a plurality of remaining range image data when the adjusted proton beam passes through different positions and different angles of the imaging object.
According to an embodiment of the present disclosure, the displacement stage is a device for placing an imaging object, capable of positional translation and angular rotation.
According to an embodiment of the present disclosure, a proton imaging apparatus moves a displacement stage from a current position to a predetermined position along a predetermined route according to the predetermined position of the displacement stage and the current position. The proton imaging device rotates the displacement table from the current angle to a predetermined angle along a predetermined rotation route according to the predetermined angle of the displacement table and the current angle. The proton imaging apparatus may adjust the angle and position of the displacement table in a manner including, but not limited to, adjusting the angle of the displacement table and then adjusting the position of the displacement table, adjusting the position of the displacement table and then adjusting the position of the displacement table to the angle of the displacement table.
According to embodiments of the present disclosure, the remaining range is less than the initial range as the energy of the proton beam is partially absorbed by the imaged object.
According to an embodiment of the present disclosure, range image data is used to record image data of the range of proton beam in the scintillator. The plurality of remaining range image data are range image data obtained when the angle and the position of the displacement stage are different. The displacement table may have a plurality of predetermined angles, each of the positions may have a plurality of predetermined positions, and the range image data may have a photographing time and a photographing number.
According to the embodiment of the disclosure, each proton beam corresponds to one position and one angle of the displacement table, and when the camera device performs one shooting, one range image data is obtained.
According to the embodiment of the disclosure, each time the angle or position of the displacement table is adjusted, the proton accelerator generates the same proton beam current, the proton beam current passes through the imaging substance on the displacement table to be incident on the scintillator after being adjusted by the collimator, and the proton imaging equipment controls the camera device to shoot the scintillator, so that a plurality of residual range image data are obtained.
In operation S105, the range image data is processed with the proton imaging device to obtain a water equivalent range, wherein the range image data includes an initial range image data and a plurality of remaining range image data, and the water equivalent range includes the initial water equivalent range and the plurality of remaining water equivalent ranges.
According to the embodiment of the disclosure, the proton imaging device may perform preprocessing, image correction, image noise reduction and other processes on the range image data respectively to obtain a plurality of corresponding depth light intensity distribution curves, take a predetermined value of the light intensity variation in the plurality of depth light intensity distribution curves as a plurality of corresponding light ranges, perform calibration processing on the plurality of light ranges respectively to obtain a plurality of target light ranges, and multiply the plurality of target light ranges with relative blocking power values of the scintillator respectively to obtain a plurality of water equivalent ranges. The preprocessing may be background removing processing, the image correction may be geometric correction, distortion correction, etc., the image noise reduction may be gaussian filtering noise reduction, median filtering noise reduction, and the calibration may be linear calibration.
In operation S106, a plurality of water equivalent lengths of the imaged object are obtained based on the water equivalent ranges, including the initial water equivalent range and the plurality of remaining water equivalent ranges.
According to embodiments of the present disclosure, the water equivalent length of the imaged object is the difference between the initial water equivalent range and the water equivalent range.
According to the embodiment of the disclosure, difference value calculation is respectively carried out on the initial water equivalent range and the multiple residual water equivalent ranges, so that multiple water equivalent lengths of the imaging object are obtained.
In operation S107, image reconstruction is performed based on the plurality of water equivalent lengths, resulting in a relative stopping power distribution image of the imaged object.
According to embodiments of the present disclosure, each pixel of the relative stopping power profile is a relative stopping power value of the imaged object. Wherein the relative blocking power is the ratio of the energy loss per unit length of the proton beam in the imaging object to the energy loss per unit length of the proton beam in the water.
According to the embodiment of the disclosure, the proton beam is generated through the proton accelerator, and is emitted to the scintillator, and the beam spot size and the proton number of the proton beam are adjusted by the collimator in the process that the proton beam reaches the scintillator, so that the imaging spatial resolution is improved, and the proton imaging dosage is reduced. The proton beam after collimator adjustment passes through the imaging object and then enters the scintillator, the camera device is controlled by the proton imaging equipment to shoot the scintillator, the range of the proton beam after adjustment in the scintillator can be obtained, the high-speed data acquisition system is not required to acquire the position information and the energy information of each proton, and meanwhile, the development of a complex data processing algorithm is avoided, so that the research and development cost of the proton imaging system is reduced. The proton beam is deposited through the scintillator, the energy of the proton beam is converted into visible light, the range of the proton beam in the scintillator is obtained, and the detection efficiency and the detection sensitivity of the proton beam energy are improved. Shooting the scintillator by a camera device to obtain range image data, and processing the range image data by using proton imaging equipment to obtain a relative stopping power distribution image of an imaged object.
According to an embodiment of the present disclosure, a scintillator is photographed with a camera device under a light shielding condition, resulting in background image data.
According to an embodiment of the present disclosure, the background image data is image data of a scintillator photographed during a proton accelerator off period. Wherein the background image data need only be acquired once.
According to an embodiment of the present disclosure, controlling a camera device to capture a remaining range of an adjusted proton beam in a scintillator by using a proton imaging apparatus, and adjusting an angle and a position of a displacement table by using the proton imaging apparatus to obtain a plurality of remaining range image data when the adjusted proton beam passes through different positions and different angles of an imaging object may include the following operations: the proton imaging equipment controls the displacement platform to translate or rotate after the last shooting of the camera device is finished; the proton imaging equipment controls the camera device to shoot the adjusted proton beam to pass through the residual range of the imaging object in the scintillator, and a plurality of residual range image data of the adjusted proton beam when passing through different positions and different angles of the imaging object are obtained.
According to an embodiment of the present disclosure, the proton imaging apparatus adjusts the displacement stage such that the displacement stage translates from an initial position to a predetermined position in a predetermined step size or such that the displacement stage rotates from an initial angle to a predetermined angle at a predetermined angle interval.
According to the embodiment of the disclosure, when the displacement table is at a specific position and a specific angle, the proton imaging device controls the camera device, so that the camera device shoots once the range of the adjusted proton beam current passing through the imaging object in the displacement table in the scintillator, and one range image data is obtained. And when the position or the angle of the displacement table is changed once, the proton imaging equipment controls the camera device to shoot the scintillator once, so that a plurality of range image data are obtained.
According to an embodiment of the present disclosure, processing range image data with a proton imaging device to obtain a water equivalent range may include the following operations: respectively carrying out image processing on the initial range image data and the plurality of residual range image data for a plurality of times based on the background image data to obtain a plurality of light ranges; and respectively performing calibration treatment on the light ranges to obtain a plurality of water equivalent ranges.
According to an embodiment of the present disclosure, the light range is the range of the proton beam in the scintillator, which is found from the distribution of scintillation photons.
According to an embodiment of the disclosure, the same multiple image processing is performed on the initial range image data and the multiple remaining range image data, where the multiple image processing may be image preprocessing, image correction processing, and the like, and light intensities in the multiple processed images are respectively overlapped along a direction of a vertical proton beam to obtain multiple depth light intensity distribution (PDL) curves, and a predetermined variation value of the light intensity on the PDL curves is taken as a light range, so as to obtain multiple light ranges, where the multiple light ranges include the initial light range and the remaining light range.
According to an embodiment of the present disclosure, the calibration process is a process of calibrating the light range according to the reference range.
According to the embodiment of the disclosure, calibration processing is performed on a plurality of light ranges according to the reference range of each light range to obtain a plurality of target light ranges, and the relative stopping power values of the plurality of target light ranges and the scintillator are multiplied to obtain a plurality of water equivalent ranges.
Fig. 2 schematically illustrates a flow chart for obtaining multiple light ranges according to an embodiment of the disclosure.
As shown in fig. 2, obtaining a plurality of light schedules includes operations S251 to S255.
In operation S251, the initial range image data and the plurality of remaining range image data are respectively de-backlighted based on the background image data to obtain a plurality of first image data.
According to an embodiment of the present disclosure, the de-background processing is processing of subtracting image values of positions corresponding to range image data and background image data.
According to the embodiment of the disclosure, according to shooting time lengths of the initial range image data and the plurality of residual range image data, image values of corresponding positions of the initial range image data and the plurality of residual range image data and background image data corresponding to the shooting time lengths can be subtracted respectively to obtain a plurality of first image data.
In operation S252, distortion correction processing is performed on the plurality of first image data, respectively, to obtain a plurality of second image data.
According to an embodiment of the present disclosure, the distortion correction process is a process of correcting distortion of the first image data due to the camera lens. The distortion correction processing can be realized by: and extracting distortion parameters of the camera device by using a mathematical calculation software camera calibration tool box (MATLAB Camera Calibration Toolbox) according to image data of a plurality of checkerboard calibration plates shot by the camera device, and applying the distortion parameters to the first image data.
According to an embodiment of the present disclosure, distortions in the plurality of first image data are corrected, respectively, to obtain a plurality of second image data.
In operation S253, noise reduction processing is performed on the plurality of second image data, respectively, to obtain a plurality of third image data.
According to an embodiment of the present disclosure, the noise reduction process is a process of removing noise pixels in the second image data by a filter function, wherein the filter function may be gaussian filter and median filter.
In operation S254, a plurality of depth light intensity distribution curves are obtained according to the light intensity signals in the plurality of third image data, respectively.
According to the embodiment of the disclosure, light intensity signals in a plurality of third image data are respectively overlapped along the direction of the vertical proton beam, a plurality of light intensity signal points are obtained after each third image data is overlapped, and each light intensity signal point is connected with the adjacent light intensity signal point to obtain a PDL curve of each third image data.
In operation S255, a plurality of light ranges are obtained according to the plurality of depth light intensity distribution curves, respectively.
According to an embodiment of the present disclosure, a position on the PDL curve where the light intensity drops to 80% of the maximum light intensity is taken as the light range.
According to the embodiment of the disclosure, the positions where the light intensities on the plurality of PDL curves drop to 80% of the maximum light intensity on the corresponding PDL curves are respectively taken, so as to obtain a plurality of corresponding light ranges.
According to the embodiment of the disclosure, after the background removing process, the distortion correcting process and the noise reducing process are respectively carried out on the initial range image data and the residual range image data, a plurality of more accurate range image data are obtained, light intensity signals in the more accurate range image data are respectively overlapped along the direction of the vertical proton beam to obtain a plurality of depth light intensity distribution curves, and the light range of the proton beam is calculated through the determined depth light intensity distribution curves.
According to an embodiment of the present disclosure, calibration processing is performed on a plurality of light ranges, respectively, to obtain a plurality of water equivalent ranges, which may include the following operations: respectively carrying out linear calibration on the plurality of light ranges to obtain a plurality of calibrated light ranges; and multiplying the plurality of calibrated light ranges by the relative stopping power value of the scintillator to obtain a plurality of water equivalent ranges, wherein the relative stopping power value of the scintillator is calculated by the element composition of the scintillator, the mass fraction of each element and the average ionization energy of each element by using the Bragg additivity rule.
According to the embodiment of the disclosure, linear fitting is performed according to a plurality of measured light ranges and corresponding reference ranges to obtain a one-dimensional linear correction coefficient, and the plurality of light ranges are subjected to one-dimensional linear correction to obtain a plurality of calibrated light ranges. The measurement light range is the range of proton beams with different energies in the scintillator, which is obtained by the proton imaging method, the reference range is the range of the proton beams with the same energy as the measurement light range in the scintillator, which is obtained by Monte Carlo simulation, and the proton beams can be proton beams with the energy between 110MeV and 150 MeV.
According to the embodiment of the disclosure, the water equivalent range is the equivalent range of the proton beam in water, and the equivalent range of the proton beam in water can be obtained according to the light range of the proton beam in the scintillator. For example, a certain proton beam can pass through 5cm of water, but can only pass through 4cm of scintillator, so the relative stopping power value of the scintillator is 1.25, and when the light range of the proton beam in the scintillator is 4cm, then the equivalent range in the water is 5cm, namely the equivalent range of the water is 5cm.
According to an embodiment of the present disclosure, a plurality of calibrated light ranges are multiplied by the relative stopping power values of the scintillator, respectively, resulting in a plurality of water equivalent ranges.
According to an embodiment of the present disclosure, obtaining a plurality of water equivalent lengths of an imaged object based on a water equivalent range, including an initial water equivalent range and a plurality of remaining water equivalent ranges, may include the operations of:
the water equivalent length of the imaged object is determined by the following formula:
WEPL＝R W0 -R W1 (1)
wherein WEPL denotes the water equivalent length of the imaged object, R W0 Represents the initial water equivalent range, R W1 Indicating the equivalent range of the remaining water.
According to embodiments of the present disclosure, the initial water equivalent range is the water equivalent range of the proton beam directly incident on the scintillator.
According to an embodiment of the present disclosure, the initial water equivalent range is subtracted by the multiple water equivalent ranges, respectively, to obtain multiple water equivalent lengths of the imaged object.
According to an embodiment of the present disclosure, performing image reconstruction based on the plurality of water equivalent lengths to obtain a relative stopping power distribution image of the imaged object may include the operations of:
image reconstruction is carried out along the path direction of the proton beam by utilizing the relation between the water equivalent length and the relative blocking capacity of the imaging object to obtain a relative blocking capacity distribution image of the imaging object, wherein the relation between the water equivalent length of the imaging object and the relative blocking capacity of the imaging object is determined by the following formula:
WEPL＝∫RSP(x,y)dl (2)
where WEPL represents the water equivalent length of the imaged object, RSP (x, y) represents the RSP value at the (x, y) position on the relative stopping power distribution image, dl represents the increment per unit length along the proton beam flow path.
According to an embodiment of the present disclosure, the image reconstruction is such that the water equivalent length is reconstructed as a relatively blocked power distribution image by an image reconstruction algorithm. The image reconstruction algorithm may be a filtered back projection method, an iterative method, or the like.
Fig. 3 schematically illustrates a flow chart for adjusting a displacement stage with a proton imaging apparatus according to an embodiment of the present disclosure.
As shown in fig. 3, adjusting the displacement stage with the proton imaging apparatus includes operations S361 to S362.
In operation S361, in response to the turning on and off of the proton accelerator, the proton imaging apparatus collects the turn-on signal and the turn-off signal emitted from the proton accelerator, and controls the camera device to take a picture between the turn-on and the turn-off of the proton accelerator in a trigger mode.
According to the embodiment of the disclosure, when the proton accelerator is on, the proton imaging device collects an on signal, when the proton accelerator is off, the proton imaging device collects an off signal, when the proton imaging device detects that the signal of the proton accelerator is the on signal, the proton imaging device controls the camera device to shoot in a trigger mode outside, and when the proton imaging device detects that the signal of the proton accelerator is the off signal, the proton imaging device controls the camera device to stop shooting in a trigger mode outside.
In operation S362, after photographing by the camera device, the proton imaging apparatus adjusts the angle and position of the displacement stage.
According to the embodiment of the disclosure, the camera device sends out a voltage pulse signal after each shooting is finished, and the proton imaging equipment adjusts the position or angle of the displacement table after receiving the voltage pulse signal sent out by the camera device.
Fig. 4 schematically illustrates a schematic diagram of a proton imaging apparatus according to an embodiment of the present disclosure.
As shown in fig. 4, the proton imaging apparatus includes a proton accelerator 410, a collimator 430, a displacement stage 460, a scintillator 470, a camera apparatus 480, and a proton imaging device 490.
According to an embodiment of the present disclosure, the collimator 430 is made of brass material, and the collimator 430 has a center with 1 circular through hole of 1mm diameter for reducing the flux of the proton beam and collimating the width of the proton beam to 1mm.
According to the embodiment of the present disclosure, the displacement stage 460 includes a turntable 440 and a horizontal guide rail 450, the displacement stage 460 has a rotation and translation function, the translation direction is a direction perpendicular to the incidence direction of protons, and the displacement stage 460 is located at the rear end of the collimator 430 for placing an imaging object.
According to an embodiment of the present disclosure, the proton imaging apparatus 490 is used to control the camera device 480 to take a picture and adjust the displacement stage 460 to translate or rotate.
According to an embodiment of the present disclosure, scintillator 470 is a plastic scintillator.
According to an embodiment of the present disclosure, the proton accelerator 410 generates a plurality of proton beams 420 with predetermined energy according to requirements, the proton beams 420 pass through the collimator 430 to obtain a plurality of adjusted proton beams, the plurality of adjusted proton beams pass through an imaging object located on the displacement table 460 and are incident on the scintillator 470, the proton imaging device 490 is connected to the camera device 480, and the camera device 480 is controlled to shoot the scintillator 470 to obtain a plurality of remaining range image data. Meanwhile, the proton imaging apparatus 490 is connected to the displacement table 460, adjusts the angle of the turn table 440 or adjusts the position of the horizontal guide 450.
According to an embodiment of the present disclosure, when there is no imaged object on the displacement table 460, the camera device 480 photographs the scintillator 470, resulting in initial range image data.
According to embodiments of the present disclosure, a proton imaging device processes and image reconstructs initial range image data and a plurality of remaining range image data to obtain a relative stopping power profile of an imaged object.
Fig. 5 schematically shows a schematic view of range image data according to an embodiment of the present disclosure.
As shown in fig. 5, fig. 5 (a) shows range image data of a 150MeV proton beam in a scintillator without a collimator, fig. 5 (b) shows range image data of a same energy proton beam in a scintillator with a collimator, and fig. 5 (c) shows range image data of a same energy proton beam in a scintillator after passing through an imaging object. As can be seen from the light intensity distribution in fig. 5 (b) and the light intensity distribution in fig. 5 (a), the collimator can effectively reduce the proton beam width. As can be seen from the light intensity distribution in fig. 5 (b) and the light intensity distribution in fig. 5 (c), the range of the proton beam in the scintillator becomes shorter after the proton beam passes through the imaging object.
Fig. 6 schematically illustrates a schematic diagram of a relative stopping power profile of an imaged object according to an embodiment of the present disclosure.
As shown in fig. 6, in fig. 6 (a), there is an imaging object 610, which is placed on a displacement table 620, and the imaging object is made of plexiglass, has a diameter of 30mm, a height of 45mm, and has 4 cylindrical through holes with a diameter of 5mm in the center. Fig. 6 (b) is a relative stopping power distribution diagram of an imaged object acquired by a proton imaging method.
According to an embodiment of the present disclosure, the RSP value of the pixel in the circle 630 in fig. 6 (b) is taken for calculation, so as to obtain a reconstructed RSP of 1.154 of the imaged object, 1.158 of the imaged object, 0.121 of the reconstructed RSP of the air round hole for the air round hole 640, and 0.001 of the reference RSP of the air round hole.
According to embodiments of the present disclosure, program code for performing computer programs provided by embodiments of the present disclosure may be written in any combination of one or more programming languages, and in particular, such computer programs may be implemented in high-level procedural and/or object-oriented programming languages, and/or assembly/machine languages. Programming languages include, but are not limited to, such as Java, c++, python, "C" or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A proton imaging method, comprising:
generating a proton beam by using a proton accelerator, and transmitting the proton beam to a scintillator;
in the process that the proton beam reaches the scintillator, the beam spot size and the proton number of the proton beam are adjusted by using a collimator, so that the adjusted proton beam is obtained;
when the adjusted proton beam does not pass through an imaging object, controlling a camera device to shoot the initial range of the adjusted proton beam in the scintillator by using proton imaging equipment to obtain initial range image data;
when the adjusted proton beam passes through an imaging object, the adjusted proton beam passes through the imaging object and then enters the scintillator, the proton imaging equipment is used for controlling the camera device to shoot the residual range of the adjusted proton beam in the scintillator, and the angle and the position of a displacement table are adjusted by the proton imaging equipment to obtain a plurality of residual range image data when the adjusted proton beam passes through different positions and different angles of the imaging object, wherein the imaging object is placed on the displacement table;
Processing range image data by using the proton imaging equipment to obtain a water equivalent range, wherein the range image data comprises the initial range image data and the plurality of residual range image data, and the water equivalent range comprises the initial water equivalent range and the plurality of residual water equivalent ranges;
obtaining a plurality of water equivalent lengths of an imaging object based on the water equivalent range, including an initial water equivalent range and the plurality of remaining water equivalent ranges;
and performing image reconstruction based on the plurality of water equivalent lengths to obtain a relative stopping power distribution image of the imaging object.
2. The method of claim 1, wherein prior to obtaining the initial range image, further comprising:
and shooting the scintillator by using the camera device under the shading condition to obtain background image data.
3. The method of claim 1, wherein controlling the camera device with the proton imaging apparatus to capture a remaining range of the adjusted proton beam in the scintillator, and adjusting an angle and a position of a displacement stage with the proton imaging apparatus, to obtain a plurality of remaining range image data when the adjusted proton beam passes through different positions and different angles of the imaged object, comprises:
The proton imaging equipment controls the displacement table to translate or rotate after the last shooting of the camera device is finished;
the proton imaging equipment controls the camera device to shoot the residual range of the adjusted proton beam passing through the imaging object in the scintillator, and a plurality of residual range image data of the adjusted proton beam passing through different positions and different angles of the imaging object are obtained.
4. The method of claim 1, wherein the processing of range image data with the proton imaging device to obtain a water equivalent range, wherein the range image data includes the initial range image data and the plurality of remaining range image data, the water equivalent range includes an initial water equivalent range and a plurality of remaining water equivalent ranges, comprising:
performing image processing on the initial range image data and the plurality of residual range image data for a plurality of times based on the background image data to obtain a plurality of light ranges;
and respectively carrying out calibration treatment on the light ranges to obtain a plurality of water equivalent ranges.
5. The method of claim 4, wherein the performing image processing on the initial range image data and the plurality of remaining range image data based on the background image data, respectively, a plurality of light ranges, comprises:
Respectively performing de-background processing on the initial range image data and the plurality of residual range image data based on the background image data to obtain a plurality of first image data;
respectively carrying out distortion correction processing on the plurality of first image data to obtain a plurality of second image data;
respectively carrying out noise reduction processing on the plurality of second image data to obtain a plurality of third image data;
obtaining a plurality of depth light intensity distribution curves according to the light intensity signals in the plurality of third image data respectively;
and obtaining a plurality of light ranges according to the plurality of depth light intensity distribution curves respectively.
6. The method of claim 4, wherein the calibrating the plurality of light ranges to obtain a plurality of water equivalent ranges comprises:
respectively carrying out linear calibration on the light ranges to obtain a plurality of calibrated light ranges;
and multiplying the plurality of calibrated light ranges by the relative blocking power value of the scintillator to obtain a plurality of water equivalent ranges, wherein the relative blocking power value of the scintillator is calculated by the element composition of the scintillator, the mass fraction of each element and the average ionization energy of each element by using the Bragg additivity rule.
7. The method of claim 1, wherein the deriving a plurality of water equivalent lengths of the imaged object based on the water equivalent range, including an initial water equivalent range and the plurality of remaining water equivalent ranges, comprises:
the water equivalent length is determined by the following formula:
WEPL＝R W0 -R W1 ；
wherein WEPL denotes the water equivalent length of the imaged object, R W0 Representing the initial water equivalent range, R W1 Indicating the remaining water equivalent range.
8. The method of claim 1, wherein the reconstructing an image based on the plurality of water equivalent lengths to obtain a relative stopping power distribution image of the imaged object comprises:
performing image reconstruction by utilizing the relation between the water equivalent length and the relative blocking power of the imaging object along the path direction of the proton beam to obtain a relative blocking power distribution image of the imaging object, wherein the relation between the water equivalent length of the imaging object and the relative blocking power of the imaging object is determined by the following formula:
WEPL＝∫RSP(x,y)dl；
where WEPL represents the water equivalent length of the imaging object, RSP (x, y) represents the relative stopping power value at the (x, y) position on the relative stopping power distribution image, dl represents the increment per unit length along the proton beam flow path.
9. A method according to claim 1 or 3, wherein said adjusting the displacement table with the proton imaging apparatus comprises:
responding to the on and off of the proton accelerator, the proton imaging equipment collects the on signal and the off signal sent by the proton accelerator, and controls the camera device to shoot between the on and off of the proton accelerator in a triggering mode;
after the camera device shoots, the proton imaging apparatus adjusts the angle and position of the displacement table.
10. A proton imaging apparatus comprising:
a proton accelerator for generating a proton beam and emitting the proton beam to the scintillator;
the collimator is used for adjusting the beam spot size and the proton number of the proton beam;
the displacement platform is used for placing the imaging object and has the functions of rotation and translation;
a scintillator for depositing energy of the proton beam and generating visible light along a proton path;
camera means for acquiring range image data of the proton beam inflow impinging on the scintillator;
and the proton imaging equipment is used for controlling the camera device to acquire range image data, adjusting the angle and the position of the displacement table, processing the range image data to obtain a plurality of water equivalent ranges, and reconstructing an image based on the water equivalent ranges to obtain a relative stopping power distribution image of the imaged object.
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