CN111408073B - Method and system for calculating dose of radiotherapy ray planar detector - Google Patents
Method and system for calculating dose of radiotherapy ray planar detector Download PDFInfo
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Abstract
The invention discloses a method for calculating the dose of a radiotherapy ray plane detector and a matched system. The content comprises the following steps: calibrating parameters of a depth deviation model of the measuring plane; receiving a three-dimensional off-patient irradiation treatment plan and a measurement plane depth position from a radiotherapy Treatment Planning System (TPS); calculating the depth deviation of the measuring plane of each field according to the therapeutic handpiece angle of each field and the depth deviation model of the measuring plane; calculating the dose distribution on the measuring plane after the depth position is deviated according to the treatment plan and the depth deviation of each field; and superposing the dose distribution of each radiation field on the shifted measuring plane to generate the dose on the calibrated measuring plane of the detector.
Description
Technical Field
The invention relates to a method for calculating the dose of a radiation detector, in particular to a method and a system for calculating the dose of a radiotherapy ray plane detector.
Background
Modern radiotherapy techniques, such as conformal Intensity Modulated Radiotherapy (IMRT) and volumetric intensity modulated radiotherapy (VMAT), require a relatively complex control of the radiotherapy apparatus to irradiate the region of a patient containing a tumor or cancer from different angles, in order to improve the efficiency and safety of the treatment while minimizing the risk of injury to surrounding body tissues. This makes radiation treatment planning increasingly complex and the importance of plan validation increasing.
In planning verification of a radiotherapy plan for a patient, it is necessary to execute a corresponding verification plan on a specific water phantom and acquire a radiation dose absorbed at a designated position using a radiotherapy radiation detector. The expected absorbed dose of the detector can also be calculated using the radiotherapy device model and the radiotherapy plan. The accuracy of dose calculation for radiotherapy planning can generally be determined by comparing the two measured and calculated doses. The principle of a planar detector is to use a detector array to measure the dose distribution over a given plane. Each pixel detector in the array may be an ionization chamber (e.g., matrix xx) or a semiconductor detector (e.g., mapheck).
Researchers have found in clinical use that the measurement results of a flat panel detector have a dependence on the incident angle of the beam. When the beam is directed perpendicularly to the detector, the detector dose measurement is more closely matched to the model calculation. As the angle of the orientation of the treatment head from the vertical increases, particularly near 90 degrees, the deviation of the detector dose measurement from the model calculation can be large, even near 11%. Researchers have attempted to correct this deviation in a phenomenological way by introducing a "correction field". The resulting "correction field", however, exhibits sensitivity to changes in angle of incidence at certain angles and cannot be explicitly expressed as a function of plant and planning parameters. Therefore, the plane detector is often used as dose verification of 0-degree angle radiation field in actual clinical quality control work. In the composite field verification (i.e. each field is not rotated to 0 degree, but is located at the original position set in the plan), the physicist generally selects a non-planar detector (e.g. ArcCHECK) with a special design, so as to eliminate the influence of the field angle on the planar detector in the design, but the cost is expensive; or choose a high precision film without angle dependence for measurement, but the film calibration and scanning process is rather complicated.
Currently, as a dose verification tool for radiotherapy planning, a planar detector lacks a method for correcting the calculated dose of non-perpendicularly incident rays on the detector based on its own structural features to conform to the measured value of the detector. The method is beneficial to performing composite field verification by using the plane detector in plan verification work, and compared with ArcCHECK and a film, the cost is reduced, and the quality control work efficiency is improved.
Disclosure of Invention
This section is for the purpose of briefly describing the subject invention, and the detailed description is provided in the detailed description of the preferred embodiments. The contents herein are not intended to limit the key elements, important features and claim of the present invention.
Based on the above-mentioned necessity of the dose calculation method of the radiotherapy ray planar detector, the invention provides a method and a system for calculating the dose of the radiotherapy ray planar detector based on the structural characteristics of the detector and considering the angle dependence characteristic of each pixel detector, so that the planar detector can be used for composite field verification in the plan verification work, thereby reducing the cost and improving the quality control work efficiency.
The invention provides a method for calculating plane dose of a radiotherapy ray plane detector. The method comprises the following steps:
step 1: calibrating parameters of a depth deviation model of the measuring plane;
step 2: receiving a three-dimensional off-patient irradiation treatment plan and a measurement plane depth position from a radiotherapy Treatment Planning System (TPS);
and step 3: calculating the depth deviation of the measuring plane of each field according to the therapeutic handpiece angle of each field and the depth deviation model of the measuring plane;
and 4, step 4: calculating the dose distribution on the measuring plane after the depth position is deviated according to the treatment plan and the depth deviation of each field;
and 5: and superposing the dose distribution of each radiation field on the shifted measuring plane to generate the dose on the calibrated measuring plane of the detector.
In some embodiments, the depth deviation model may use the formula:
wherein, Δ d is the position depth deviation, θ is the angle of the therapeutic head of the radiation field, and a and b are the length of the semimajor axis and the length of the semiminor axis of the semielliptical model of the effective measuring point track of the pixel probe of the detector.
In some embodiments, step 1 comprises at least the following steps:
step 1.1: rotating a square field formed by a collimator by a plurality of angles around an isocenter;
step 1.2: irradiating a fixed number of machine doses at each angle;
step 1.3: measuring the planar dose distribution of each angle in an isocenter plane by using a detector to be calibrated;
step 1.4: calculating the dose distribution of each angle radiation field in the isocenter plane;
step 1.5: calculating the translation deviation delta x between the calculated dose distribution and the measured dose distribution of each angle field in the isocenter plane;
step 1.6: calculating the optimal fitting parameters a and b by using the following formulas;
wherein, Δ x is the translation deviation between the calculated dose distribution and the measured dose distribution, θ is the angle of the portal treatment head, and a and b are the length of the semi-major axis and the length of the semi-minor axis of the semi-elliptical model of the effective measuring point track of the detector pixel probe; the optimization goal is to minimize the mean square average of the difference between the translational deviation Δ x between the calculated dose distribution and the measured dose distribution of each angular field at the isocenter plane and the translational deviation resulting from the calculation formula in this step.
In some embodiments, the rays include, but are not limited to: photon rays, electron rays, proton rays, and heavy ion rays.
In some embodiments, the planar detector includes, but is not limited to: ionization chamber matrix detectors and semiconductor matrix detectors.
In some embodiments, the method for calculating the radiation therapy dose includes, but is not limited to: table interpolation, convolution superposition, and monte carlo.
The invention relates to a system for calculating plane dose of a radiotherapy ray plane detector, and provides a system which has computer codes stored in a non-volatile storage medium and can be used for calculating plane dose of the radiotherapy ray plane detector. The system comprises the following parts:
the detector calibration module is responsible for calibrating parameters of a track model of effective measurement points of the pixel probe; a planar dose calculation module responsible for receiving an off-patient treatment plan and measuring planar depth positions from a radiotherapy Treatment Planning System (TPS); calculating the depth deviation of the measuring plane of each field according to the therapeutic handpiece angle of each field and the depth deviation model of the measuring plane; calculating the dose distribution on the measuring plane after the depth position is deviated according to the treatment plan and the depth deviation of each field; and superposing the dose distribution of each radiation field on the shifted measuring plane to generate the dose on the calibrated measuring plane of the detector. The detector calibration module and the plane dose calculation module are in data communication through a data bus or a data network.
In some embodiments, the depth deviation model may use the formula:
wherein, Δ d is the position depth deviation, θ is the angle of the therapeutic head of the radiation field, and a and b are the length of the semimajor axis and the length of the semiminor axis of the semielliptical model of the effective measuring point track of the pixel probe of the detector.
In some embodiments, the step of calibrating the parameters of the trajectory model of the effective measurement points of the pixel probe comprises at least the following steps:
step 2.1: rotating a square field formed by a collimator by a plurality of angles around an isocenter;
step 2.2: irradiating a fixed number of machine doses at each angle;
step 2.3: measuring the planar dose distribution of each angle in an isocenter plane by using a detector to be calibrated;
step 2.4: calculating the dose distribution of each angle radiation field in the isocenter plane;
step 2.5: calculating the translation deviation delta x between the calculated dose distribution and the measured dose distribution of each angle field in the isocenter plane;
step 2.6: calculating the optimal fitting parameters a and b by using the following formulas;
wherein, Δ x is the translation deviation between the calculated dose distribution and the measured dose distribution, θ is the angle of the portal treatment head, and a and b are the length of the semi-major axis and the length of the semi-minor axis of the semi-elliptical model of the effective measuring point track of the detector pixel probe; the optimization goal is to minimize the mean square average of the difference between the translational deviation Δ x between the calculated dose distribution and the measured dose distribution of each angular field at the isocenter plane and the translational deviation resulting from the calculation formula in this step.
In some embodiments, the rays include, but are not limited to: photon rays, electron rays, proton rays, and heavy ion rays.
In some embodiments, the planar detector includes, but is not limited to: ionization chamber matrix detectors and semiconductor matrix detectors.
In some embodiments, the method for calculating the radiation therapy dose includes, but is not limited to: table interpolation, convolution superposition, and monte carlo.
Drawings
The following description is intended to more clearly describe the invention in connection with the detailed description thereof and not to limit the scope of the invention, which is defined by the appended claims.
Fig. 1 is a flow chart of the method for calculating the plane dose of the radiotherapy ray plane detector of the invention.
FIG. 2 is a sub-flow diagram of the parameters of the depth deviation model used to calibrate the measurement plane of the present invention.
FIG. 3 is a system diagram of one embodiment of the present invention.
FIG. 4 is a schematic view of a phantom and flat panel detector arrangement for measuring dose distribution in accordance with an embodiment of the present invention.
FIG. 5 is a schematic diagram of the dependence of a planar detector on the angle of incidence of a radiation beam as described by the depth deviation model of the present invention.
FIG. 6 is a schematic illustration of an equivalent measured planar dose distribution and a difference between the measured planar dose distributions in one embodiment of the present invention.
Fig. 7 is a schematic illustration of the derivation of equations 1, 2, 3, 4 in one embodiment of the present invention.
Detailed Description
In the following description, reference is made to the accompanying drawings and specific examples, which illustrate the preferred embodiments of the present invention and, therefore, will be understood by those skilled in the art how the following detailed description of the preferred embodiments of the present invention may be made.
The innovative concepts embodied in the present invention can be embodied in a wide variety of embodiments. Therefore, the detailed description of the preferred embodiments should not be read as limiting the claims to the innovative concepts presented herein, but rather as an aid to those skilled in the art in understanding the innovative concepts contained herein. In addition, the size and relative size of the layers and portions of the objects in the schematic diagram are appropriately modified to avoid overlap.
A description object of an illustration is indicated in the diagram in the form of a reference number. However, in the schematic diagrams of the embodiments of the present invention, not all the components are numbered. The reasons include: 1) information disclosed in the related art will not be described in detail herein; 2) the parts overlapping with the context will not be described in detail.
The present invention is described herein using the term "comprising" to refer to the objects contained in the present invention. If not explicitly stated in the context, such reference is to be an inexhaustible recitation that omits some information from the description and is believed to not affect the understanding of the methods of the present invention by those skilled in the art.
The detailed description herein may use certain terminology with precedence relationships to facilitate the listing of objects to be described. These terms should not be construed as limiting the composition and structure of the method of the invention, but should be construed as merely providing temporary labels to distinguish between the items so described, and transposing the order of the items so described, e.g., the first item and the second item, without affecting the description herein of the innovative concepts of the invention. Similarly, when the term "and/or" is used herein to connote a group of statements, there is no intention to be bound by any expressed combination of the order in which such statements occur. Any change in the order of presentation of these objects is acceptable.
Unless specific terms are set forth herein to give a unique definition to a given term, the terms used in the detailed description are consistent with the usage habits of those skilled in the art to which the present invention pertains. Additionally, the description herein may use certain words of everyday usage to describe the present invention. If the reader finds that these terms are defined in an idealized or informal manner, consistent with the context in which they are used, then unless a clear definition is given, it should be understood that these terms are used herein in a generic and generic dictionary based on their interpretation to conform to the use conventions used in the art.
"radiation therapy" or "radiotherapy" refers to the use of a directable radiation therapy device to emit a "radiation beam" of energetic particles to a region of a patient's body occupied by cancerous cells or tumors so as to produce a radiation absorbed dose in the region to directly destroy the DNA of the cells in the region, or to indirectly destroy the DNA by generating charged particles in the cells. Cells repair DNA damage and when the repair capacity is insufficient to restore DNA damage, cells stop dividing or die. But this process can also cause damage to healthy cells of vital organs and anatomical structures surrounding the area. Therefore, one of the important links of the radiation therapy planning process is to make accurate segmentation based on high-precision medical images in order to ensure avoidance of vital organs when planning radiotherapy, minimize the amount of absorbtion that forms in healthy tissue, and completely cover the entire target area in order to reduce the probability of recurrence.
"radiotherapy planning" or "radiotherapy planning" is a step in the radiation therapy process, which is performed by a group of professionals, including: a radiation oncologist, a radiation therapist, a medical physicist, a medical dosimeter to design a plan for external radiation therapy of a patient with a tumor; the resulting treatment plan is referred to as a "radiotherapy plan". Generally, a medical image of a patient is first processed to obtain a "segmentation" and then a radiotherapy plan is designed based thereon. "segmentation" as used herein refers to the use of a set of regions of interest to describe the correspondence of pixels in a medical image to target areas, vital organs, and other human anatomy within the human body.
"Treatment Planning System" (TPS) generally refers to computer software that can be used to quickly assist in Planning a radiation Treatment plan. In this context, this document refers specifically to a full-flow radiation treatment planning system software developed by the present company for assisting a physician in planning and evaluating a radiation treatment plan.
"dose verification of radiotherapy plan" means that radiotherapy equipment is operated to deliver radiotherapy to a model according to a radiotherapy plan and simultaneously absorbed dose is measured at a designated measurement point by using dose measurement equipment; the absorbed dose distribution thus measured is compared with the expected dose distribution proposed by the radiotherapy plan, and the degree of agreement of the planned expected value of the dose with the actual measured value at the measuring point is counted according to a certain criterion (e.g. 3%/3 mm). The statistics may be used to describe how well the radiotherapy device fits the model of the device.
An "ionization chamber" is a gas detector that detects ionizing radiation. When the detector is irradiated with radiation, the radiation interacts with molecules in the gas to produce an ion pair consisting of an electron and a positive ion. These ions are free to diffuse to the surrounding area. During diffusion, electrons and positive ions can recombine to form neutral molecules. However, when a direct-current polarization voltage is applied to a collector and a high-voltage electrode constituting a gas detector to form an electric field, electrons and positive ions are respectively pulled to the positive and negative electrodes and collected, thereby forming an electric signal. In the field of radiation therapy, ionization chambers may be used to measure the radiation absorbed dose at a given point.
"planar detectors" may be used to measure the absorbed dose of radiotherapy radiation with respect to a given plane during verification of a radiotherapy plan, and typically consist of a two-dimensional detector lattice, including, but not limited to: ionization chamber matrix detectors and semiconductor matrix detectors.
Ionization chamber matrix detector "
The plane detector is composed of a two-dimensional ionization chamber lattice. Common brands of ionization chamber matrix detectors include: i' mRT matrix XX (IBA Dosimery, Germany).
Embodiments of the present invention are primarily directed to correcting measurement results based on a depth deviation model when using a planar detector for dose measurement of a radiation beam, so that accurate planar dose measurement data can be obtained. In some embodiments, software and hardware designed according to the present invention can also be used to help physicians more effectively complete the verification of radiotherapy plan quality. In some embodiments, the present invention is incorporated as part of a radiation Therapy Planning System (TPS) for processing planar dose data and eliminating the deviation of the measured data from the planar detector due to its dependence on the angle of incidence of the radiation beam during a radiation therapy planning quality verification procedure to more accurately perform the radiation therapy planning quality verification.
Fig. 1 is a flow chart 100 of a method of calculating a planar dose of a radiotherapy radiation planar detector of the present invention. The figure illustrates the steps for calibrating the survey plane measurement data using a depth offset model. The specific implementation steps comprise:
starting at step 101.
In step 102, the reference data is used to calibrate parameters of the depth deviation model of the measurement plane.
In step 103, a three-dimensional off-patient radiation treatment plan and measurement plane depth positions are received from a radiotherapy Treatment Planning System (TPS).
In step 104, the depth deviation of the measurement plane of each field is calculated according to the angle of the treatment head and the depth deviation model of the measurement plane.
In step 105, the dose distribution on the measurement plane after depth position offset is calculated from the treatment plan and the depth offset for each field.
In step 106, the dose distributions of the fields on the shifted measurement plane are superimposed to generate the dose on the calibrated measurement plane of the detector.
Ending in step 107.
In some embodiments, when calibrating parameters of the depth deviation model of the measurement plane at step 102, the depth deviation in the depth deviation model may be represented as equation 1.
Fig. 2 is a sub-flowchart 200 of the present invention for calibrating parameters of a depth deviation model of a measurement plane, for explaining the necessary steps of the process of calibrating the parameters of the depth deviation model in step 102 of the flowchart 100 of the method of fig. 1 for calculating a planar dose of a radiotherapy radiation planar detector. The method comprises the following steps:
starting at step 201.
At step 202, a collimator is set to a square field for modulating the radiation beam, for which a number of angles of incidence are selected around the isocenter.
In step 203, a fixed number of machine doses is irradiated at each angle.
At step 204, the planar dose distribution for each angle is measured at the isocenter plane with the detector to be calibrated while the accelerator is irradiating the radiation dose specified in step 203 with the field and angle at step 202.
In step 205, a planar dose distribution of the isocenter plane is calculated based on the field and angle specified in step 202 and the number of machine hops specified in step 203 using a dose calculation function of the radiotherapy planning system.
At step 206, a translational deviation Δ x between the calculated dose distribution and the measured dose distribution for each angular field at the isocenter plane is calculated.
In step 207, fitting parameters a and b are optimized with respect to the depth deviation model based on equation 2; the optimization goal is to minimize the mean square average of the difference between the translational deviation Δ x between the calculated dose distribution and the measured dose distribution of each angular field at the isocenter plane and the translational deviation resulting from the calculation formula in this step.
Ending in step 208.
In some embodiments, the field set in step 202 may be a rectangular field, for example: a field of 4cm × 10 cm. The angle selected in step 202 may be a set of equally spaced angles, for example: 0 °, ± 40 °, ± 80 °, ± 120 °, ± 160 °. The planar detectors that may be calibrated in step 204 include, but are not limited to: ionization chamber matrix detectors and semiconductor matrix detectors.
FIG. 3 is a system diagram of one embodiment of the present invention. In this system, a flat panel detector dose data processing system 303 takes as input and saves to a storage device the data generated by the flat panel detector 301 and the radiation Treatment Planning System (TPS)302, and the user manipulates the system, provides input, and views the processing results through a user interface 305. The three devices exchange data over the local area network 314. The components of the flat panel detector dose data processing system 303 are interconnected by an internal bus 321. The system, under the control of the processor 304, manipulates the storage device 306 to read or save files, establishes a processing engine 307 in memory, responds to operations from the user interface 305, or displays processing results on the user interface 305. The method comprises the following specific steps:
the user acquires measurement data 315 of dose distribution on a set of measurement planes using the plane detector 301 and calculation data 316 of dose distribution on a set of same measurement planes using the radiation Treatment Planning System (TPS)302 based on the same set of plans for calibration. The measurement data 315 and the calculation data 316 acquired by the flat panel detector dose data processing system 303 form a calibration data set 310 and are stored on the storage device 306. The model parameter calibration module 313 reads the calibration data set 310 from the storage device 306 as input, optimizes and fits parameters of the depth deviation model, and saves the optimized parameters as output to the model setup file 309.
After calibration of the model parameters is complete, the user may process a set of dose distribution data 317 using the flat panel detector dose data processing system 303 for calculation and display on the user interface 305 of a set of measured flat panel dose distribution data 320. The method comprises the following specific steps:
the planar detector dose data processing system 303 acquires a radiation therapy plan from a radiation Therapy Planning System (TPS)302, which includes dose distribution data 317 on a measurement plane. This data is stored on the storage device 306 as a dose distribution data set 308. The depth offset calculation module 312 loads a calibrated depth offset model via the input model setup file 309. The dose distribution dataset 308 will be input to the dose calculation module and the corrected measurement plane dose distribution 320 will be calculated from the deviation depth deviation 319 generated by the depth deviation model calculation. The measurement plane dose distribution 320 is passed to the user interface 305 for display as a dose distribution corresponding to the user-specified measurement plane depth value 318.
Thus, the user can process the dose distribution data 317 contained in the radiotherapy plan using the flat panel detector dose data processing system 303, outputting a calculated dose distribution 320 that can be compared to the actual measured dose. .
FIG. 4 is a schematic illustration of the placement of a phantom and a flat panel detector in measuring dose distribution at normal incidence in an embodiment of the invention. Wherein the upper layer of solid water 402, the plane detector 403 and the lower layer of solid water 404 are horizontally stacked. The distance from the light source 401 to the upper surface of the upper layer of solid water 402 is denoted SSD. The distance from the light source 401 to the upper surface of the flat panel detector 403 is denoted SSmD. The distance from the light source 401 to the measurement plane 406 is denoted SMeaD. The thickness of the upper layer of solid water 402 is shown as Dwu and the thickness of the lower layer of solid water 404 is Dwl. The distance between the probe upper surface 405 and the measurement plane 406 is denoted as Dmea.
FIG. 5 is a schematic diagram of the dependence of a planar detector on the incident angle of a radiation beam as described by the depth deviation model of the present invention. The flat panel detector is composed of a group of detector units arranged in a two-dimensional lattice form. Each unit may be structurally divided into two parts: an absorbing material 501, a pixel chamber 506; the lower surface of the absorbing material 501 is in contact with the upper surface of the pixel chamber 506, the contact surface being part of the measurement plane 503; the default measurement point 502 is located at the geometric center of the contact portion. In practical use, the incident angle of the beam can be divided into two cases: beam one 507 incident from the absorbing material 501 side of the measurement plane 503, beam two 508 incident from the pixel chamber 506 side of the measurement plane 503. Since the planar detector has an angular dependence with respect to the beam when measuring the radiation beam dose, the equivalent measurement plane 504 is offset by a depth value from the measurement plane 503 to the side of the pixel chamber 506. For beam one 507, the transmitted portion enters the pixel chamber 506. The intersection of the transmitted light passing through the measurement point 502 and the equivalent measurement plane 504 is regarded as the equivalent measurement point 505 of the first beam 507. For beam two 508, a reflected portion enters pixel chamber 506. The intersection of the reflected light passing through the measurement point 502 and the equivalent measurement plane 504 is regarded as an equivalent measurement point 505 of the beam two 508. The equivalent measurement points 505 constitute a trace 509 consisting of half an ellipse as the angle of incidence changes. The semi-major and semi-minor axes of the ellipse are a and b, respectively. Thus, the deviation Δ d of the measurement plane and the horizontal deviation Δ x of the measured dose can be expressed by equation 1 and equation 2, respectively. The derivation of these equations is illustrated by fig. 7. Thus, the method proposed by the present invention can be used to calibrate the parameters of the depth deviation model from the reference dose distribution data and adjust the dose distribution on the dose plane using the deviation of the equivalent measurement point 505 of each detector unit of the planar detector from the measurement point 502 according to the calibrated depth deviation model.
FIG. 6 is a schematic illustration of the difference between an uncorrected calculated dose distribution and a measured dose distribution on a measurement plane in one embodiment of the present invention, comprising: the measured value is compared 601 with the calculated value for an incident angle of 40 °, 602 with the calculated value for an incident angle of 80 °, 603 with the calculated value for an incident angle of 120 °, and 604 with the calculated value for an incident angle of 160 °. The translational offsets between the respective uncorrected calculated dose distributions and the measured dose distributions can be used to optimize the parameters of the calibration field depth offset model, i.e. the semi-major and semi-minor axes of the trajectory 509 consisting of half an ellipse made up of the equivalent measurement points 505 are a and b, respectively.
Fig. 7 is a schematic illustration of the derivation of equations 1, 2, 3, 4 in one embodiment of the present invention. The variables used in the formula are plotted against each other. In the figure, the horizontal axis 701 and the vertical axis 702 are perpendicular to each other and intersect at the origin. An ellipse 710 with major axis along the lateral axis and minor axis along the longitudinal axis, semi-major axis a, semi-minor axis b, and geometric center at the origin. The circumscribed circle 711 and the inscribed circle 709 of the ellipse are respectively drawn by taking the origin as the center of a circle and the major axis and the minor axis of the ellipse as the diameters. Point P703 is a point on the ellipse with coordinates (x, y). The projection 705 of this point on the horizontal axis is (x, 0) on the horizontal axis and the projection 706 on the vertical axis is (0, y) on the vertical axis. The circumscribed circle 711 has a point Q and a straight line passing through Q, P is perpendicular to the transverse axis 701. The length of a line segment from the original point to the point P is r, the included angle between the line segment and the horizontal axis is phi, and the included angle between the line segment and the vertical axis is theta. The line segment from the origin to the point Q forms an included angle with the horizontal axis
Accordingly, the coordinate value of point P may be expressed as a function of variables such as the length of the semi-major axis, the semi-minor axis, the length of the line segment from the origin to point P, and the angle between the two line segments and the horizontal axis 701:
in the formula eliminate
The distance r from the origin to point P can be expressed as a function of the semi-major axis a, the semi-minor axis b, and the angle phi:
thus, the coordinates of the P point can be expressed as:
since θ + Φ is pi/2, replacing Φ with θ can result in:
referring to fig. 5, the origin is a measurement point 502 on a measurement plane 503, the incident angle of the beam one 507 is directed from a point P703 to the origin, the incident angle is θ, and the incident angle is acute. According to the depth deviation model, the equivalent measurement point 505 is shifted in the depth direction by Δ d and Δ x along the incident direction of the beam one 507 from the origin to obtain one of the equivalent measurement points 505. When the incident angle is θ and is an obtuse angle, i.e., beam two 508, according to the depth deviation model, the equivalent measurement point 505 is shifted from the origin by Δ d in the depth direction and Δ x in the horizontal direction against the incident direction of beam two 508, resulting in another one of the equivalent measurement points 505. Then, according to equation 8, in conjunction with fig. 5 and fig. 7, for the case of beam one 507 and beam two 508, the shift Δ d and the horizontal shift Δ x in the depth direction of the equivalent measurement point 505 with respect to the measurement point 502 can be expressed as:
and
although specific embodiments of the invention have been described herein with reference to specific examples, it will be understood by those skilled in the art that: various embodiments that can be used in the same context can be made by substituting equivalent components or other methods in the embodiments without departing from or departing from the innovative concepts and methods of the present invention, and the embodiments can be made to function in the same way depending on the specific environment of use, requirements, available materials, composition of processing objects, or requirements for workflow. Such modifications are intended to fall within the scope of the appended claims without violating or deviating from the innovative concepts and methods presented herein.
Claims (10)
1. A method for calculating plane dose of a radiotherapy ray plane detector is characterized by comprising the following steps: the method comprises the following steps:
step 1: calibrating parameters of a depth deviation model of the measuring plane; the step 1 further comprises the step of,
step 1.1, rotating a square field formed by a collimator by a plurality of angles around an isocenter;
step 1.2, irradiating the ray doses of a fixed machine number at each angle;
step 1.3, measuring the planar dose distribution of each angle on an isocenter plane by using a detector to be calibrated;
step 1.4, calculating the dose distribution of each angle field in the isocenter plane based on the field and angle specified in step 1.1 and the number of machines specified in step 1.2;
step 1.5, calculating the translation deviation (delta x) between the calculated dose distribution and the measured dose distribution of each angle field in the isocenter plane;
step 1.6, optimizing and fitting the parameters of the depth deviation model, wherein the optimization target is to minimize the mean square value of the difference between the translational deviation (delta x) between the calculated dose distribution and the measured dose distribution of each angle field on the isocenter plane and the translational deviation calculated by the depth deviation model in the step, the fitting parameters a and b are optimized by adopting the following formula,
wherein, Δ x is the translation deviation between the calculated dose distribution and the measured dose distribution, θ is the angle of the portal treatment head, and a and b are the length of the semi-major axis and the length of the semi-minor axis of the semi-elliptical model of the effective measuring point track of the detector pixel probe;
step 2: receiving a three-dimensional off-patient irradiation treatment plan and a measurement plane depth position from a radiotherapy Treatment Planning System (TPS);
and step 3: calculating the depth deviation of the measuring plane of each field according to the therapeutic handpiece angle of each field and the depth deviation model of the measuring plane;
and 4, step 4: calculating the dose distribution on the measuring plane after the depth position is deviated according to the treatment plan and the depth deviation of each field;
and 5: and superposing the dose distribution of each radiation field on the shifted measuring plane to generate the dose on the calibrated measuring plane of the detector.
2. The method of claim 1, wherein the planar dose of the radiation therapy planar detector is calculated by: the depth deviation model can adopt a formula:
wherein, Δ d is the position depth deviation, θ is the angle of the therapeutic head of the radiation field, and a and b are the length of the semimajor axis and the length of the semiminor axis of the semielliptical model of the effective measuring point track of the pixel probe of the detector.
3. The method of claim 1, wherein the planar dose of the radiation therapy planar detector is calculated by: the radiation includes photon radiation, electron radiation, proton radiation and heavy ion radiation.
4. The method of claim 1, wherein the planar dose of the radiation therapy planar detector is calculated by: the plane detector comprises an ionization chamber matrix detector and a semiconductor matrix detector.
5. The method of claim 1, wherein the planar dose of the radiation therapy planar detector is calculated by: the calculation method of the radiotherapy dose comprises a table lookup interpolation method, a convolution superposition method and a Monte Carlo method.
6. A system having computer code stored on a non-volatile storage medium that can be used to calculate a planar dose for a radiation planar detector of radiation therapy, comprising:
the detector calibration module is responsible for calibrating parameters of a track model of effective measurement points of the pixel probe; a planar dose calculation module responsible for receiving an off-patient treatment plan and measuring planar depth positions from a radiotherapy Treatment Planning System (TPS); calculating the depth deviation of the measuring plane of each field according to the therapeutic handpiece angle of each field and the depth deviation model of the measuring plane; calculating the dose distribution on the measuring plane after the depth position is deviated according to the treatment plan and the depth deviation of each field; overlapping the dose distribution of each radiation field on the shifted measuring plane to generate the dose on the calibrated measuring plane of the detector; wherein the detector calibration module and the planar dose calculation module are in data communication via a data bus or a data network, the detector calibration module is specifically configured to,
rotating a square field formed by a collimator by a plurality of angles around an isocenter;
irradiating a fixed number of machine doses at each angle;
measuring the planar dose distribution of each angle in the isocenter plane by using a detector to be calibrated;
calculating the dose distribution of each angular field in the isocenter plane based on the specified field and angle and the specified number of machines;
calculating a translational deviation (Δ x) between the calculated dose distribution and the measured dose distribution for each angular field at the isocenter plane;
optimizing parameters of the depth deviation model, wherein the optimization target is to minimize the mean square value of the difference between the translational deviation (delta x) between the calculated dose distribution and the measured dose distribution of each angle field in the isocenter plane and the translational deviation calculated by the depth deviation model in the step, the fitting parameters a and b are optimized by adopting the following formula,
wherein, Δ x is the translation deviation between the calculated dose distribution and the measured dose distribution, θ is the angle of the portal treatment head, and a and b are the length of the semi-major axis and the length of the semi-minor axis of the semi-elliptical model of the effective measuring point track of the detector pixel probe.
7. The system for calculating the planar dose of a radiation therapy planar detector according to claim 6, wherein: the depth deviation model can adopt a formula:
wherein, Δ d is the position depth deviation, θ is the angle of the therapeutic head of the radiation field, and a and b are the length of the semimajor axis and the length of the semiminor axis of the semielliptical model of the effective measuring point track of the pixel probe of the detector.
8. The system for calculating the planar dose of a radiation therapy planar detector according to claim 6, wherein: the radiation includes photon radiation, electron radiation, proton radiation and heavy ion radiation.
9. The system for calculating the planar dose of a radiation therapy planar detector according to claim 6, wherein: the plane detector comprises an ionization chamber matrix detector and a semiconductor matrix detector.
10. The system for calculating the planar dose of a radiation therapy planar detector according to claim 6, wherein: the calculation method of the radiotherapy dose comprises a table lookup interpolation method, a convolution superposition method and a Monte Carlo method.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101011617A (en) * | 2006-12-29 | 2007-08-08 | 成都川大奇林科技有限责任公司 | Method for determining radiating field output dose accurately in conformalradiotherapy |
| CN104606796A (en) * | 2014-02-19 | 2015-05-13 | 北京市医疗器械检验所 | Dose calculation error testing method of radiotherapy system and phantom |
| CN106345072A (en) * | 2016-09-21 | 2017-01-25 | 山东师范大学 | Real-time detecting method and system for multi-leaf collimator blade position of linear accelerator |
| CN106500577A (en) * | 2016-10-20 | 2017-03-15 | 山东省千佛山医院 | A kind of clinac vane grating method for detecting position |
| CN108175954A (en) * | 2017-12-29 | 2018-06-19 | 苏州雷泰医疗科技有限公司 | A kind of tablet energy detection device, detection method and accelerator therapy device |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1438602A (en) * | 2003-03-17 | 2003-08-27 | 吴大可 | Radiotherapy system of automatic computing prescription dosage |
| JP6083693B2 (en) * | 2012-09-13 | 2017-02-22 | 国立研究開発法人量子科学技術研究開発機構 | Dose distribution measurement system and dose distribution measurement method |
| US8927921B1 (en) * | 2012-10-02 | 2015-01-06 | Sun Nuclear Corporation | Systems and methods for composite dose quality assurance with three dimensional arrays |
| CN105263577B (en) * | 2013-06-06 | 2018-05-01 | 三菱电机株式会社 | The setting method of particle-beam therapeutic apparatus and dose modifying factor |
| CN105288870B (en) * | 2015-11-03 | 2017-03-01 | 上海联影医疗科技有限公司 | A kind of calibration steps of multi-diaphragm collimator |
| CN105825073B (en) * | 2016-06-17 | 2018-08-14 | 张家港赛提菲克医疗器械有限公司 | A kind of online radiotherapy planning quality control system |
| CN106215331A (en) * | 2016-07-06 | 2016-12-14 | 中国科学院合肥物质科学研究院 | A kind of fast dose verification method based on x-ray imaging flat panel detector |
| ES2625761B1 (en) * | 2016-08-10 | 2018-04-10 | María Del Carmen OVEJERO MAYORAL | METHOD FOR AUTOMATION IN DOSIMETRIC CALIBRATION, RECONSTRUCTION AND VERIFICATION OF COMPREHENSIVE TREATMENTS OF INTEGRATED RADIOTHERAPY IN AN ENVIRONMENT AND SYSTEM FOR PRACTICE OF THE SAME |
| CN107823806B (en) * | 2017-09-15 | 2019-11-19 | 中北大学 | A kind of method and system for the direct Ziye optimization of intensity-modulated radiation therapy |
| CN107913079B (en) * | 2017-11-22 | 2022-03-01 | 上海联影医疗科技股份有限公司 | Radiation field verification device and method for medical equipment |
| CN110404184A (en) * | 2019-06-13 | 2019-11-05 | 苏州同调医学科技有限公司 | A kind of method and system of measuring and calculating radiotherapy roentgen dose X distribution and dose objective function |
| CN110787376B (en) * | 2019-11-29 | 2021-04-06 | 合肥中科离子医学技术装备有限公司 | Tumor patient positioning system based on proton imaging |
-
2020
- 2020-03-24 CN CN202010253643.2A patent/CN111408073B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101011617A (en) * | 2006-12-29 | 2007-08-08 | 成都川大奇林科技有限责任公司 | Method for determining radiating field output dose accurately in conformalradiotherapy |
| CN104606796A (en) * | 2014-02-19 | 2015-05-13 | 北京市医疗器械检验所 | Dose calculation error testing method of radiotherapy system and phantom |
| CN106345072A (en) * | 2016-09-21 | 2017-01-25 | 山东师范大学 | Real-time detecting method and system for multi-leaf collimator blade position of linear accelerator |
| CN106500577A (en) * | 2016-10-20 | 2017-03-15 | 山东省千佛山医院 | A kind of clinac vane grating method for detecting position |
| CN108175954A (en) * | 2017-12-29 | 2018-06-19 | 苏州雷泰医疗科技有限公司 | A kind of tablet energy detection device, detection method and accelerator therapy device |
Non-Patent Citations (3)
| Title |
|---|
| 一种用于调强适形放疗剂量验证模型的研究;曹明娜等;《医疗卫生装备》;20110615(第06期);全文 * |
| 放射治疗剂量验证的现状及进展;朱煜和等;《生物医学工程学杂志》;20131225(第06期);全文 * |
| 肿瘤调强放射治疗计划的剂量学验证;胡杰等;《医疗卫生装备》;20160815(第08期);全文 * |
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