A multifunctional phantom

Abstract

The present invention provides a multifunctional phantom, including: a machine geometry deviation detector, an imaging system detector and an isocenter detector; a plurality of metal markers are arranged in the machine geometry deviation detector; a plurality of grooves are arranged on the machine geometry deviation detector, and the metal markers are arranged in the grooves; the imaging system detector includes: a first cylinder and a second cylinder; two metal wire pairs are arranged in the first cylinder; each metal wire pair includes two oppositely arranged metal wires; two metal wires in one metal wire pair have a preset angle with the bottom surface of the first cylinder; two metal wires in another metal wire pair are parallel to the bottom surface of the first cylinder; four cylindrical plug-ins with different densities are arranged in the second cylinder; the isocenter detector is a cylinder, the bottom is connected to the second cylinder, the top is hemispherical, and a sphere is embedded in the upper part of the isocenter detector. The present invention can be used to perform multiple measurement simulations on radiotherapy equipment.

Description

Technical Field

[0001] The present application relates to the technical field of radiotherapy, and in particular to a multifunctional phantom. Background Art

[0002] In the prior art, devices including airborne two-dimensional or three-dimensional image acquisition systems, automatic image analysis software, and automatic quality control functions of multi-functional phantoms have been proposed to increase the inspection frequency of equipment, reduce manual operations, and thus ensure the accuracy of radiotherapy.

[0003] For example, based on the TG198AAPM international accelerator quality control guidelines and taking into account the characteristics of the CNNC particle accelerator, 17 quality control items can be selected for daily execution, 15 of which are automatically implemented by software (laser light alignment and safety checks are performed manually). Six of the 15 quality control items require the use of phantoms for imaging and analysis of equipment indicators.

[0004] However, the phantoms in the prior art can usually only perform relevant tests on a specific test item, but cannot test multiple test items at the same time. Summary of the invention

[0005] In view of this, the present invention provides a multifunctional phantom, which can perform multiple measurement simulations on radiotherapy equipment and effectively meet the measurement requirements of various measurement indicators.

[0006] The technical solution of the present invention is specifically achieved as follows:

[0007] A multifunctional phantom, the multifunctional phantom comprising: a machine geometry deviation detector, an imaging system detector and an isocenter detector;

[0008] The machine geometric deviation detector is provided with a plurality of metal markers, each of which is arranged at a preset position in the machine geometric deviation detector; the machine geometric deviation detector is provided with a plurality of grooves, and the metal markers are arranged in the grooves respectively;

[0009] The imaging system detector comprises: a first cylinder and a second cylinder; the bottom of the first cylinder is connected to one side of the machine geometric deviation detector; the top of the first cylinder is connected to the bottom of the second cylinder;

[0010] Two metal wire pairs are arranged in the first cylinder; each metal wire pair includes two metal wires arranged opposite to each other; a preset angle is formed between the two metal wires in one metal wire pair and the bottom surface of the first cylinder; and the two metal wires in the other metal wire pair are parallel to the bottom surface of the first cylinder;

[0011] The second cylinder is provided with four cylindrical inserts having different densities;

[0012] The isocenter detector is a cylinder, and the bottom of the isocenter detector is connected to the second cylinder of the imaging system detector; the top of the isocenter detector is hemispherical, and a sphere is embedded in the upper part of the isocenter detector.

[0013] Preferably, a connecting device is provided on one side of the machine geometric deviation detector;

[0014] The connecting device is used to fix the machine geometry deviation detector on the treatment bed.

[0015] Preferably, a leveling device is provided at the bottom of the machine geometric deviation detector;

[0016] The leveling device is used to adjust the horizontality of the multifunctional mold body.

[0017] Preferably, the metal marker is a steel ball.

[0018] Preferably, the number of the metal markers is 13.

[0019] Preferably, the machine geometry deviation detector is a cube.

[0020] Preferably, the preset angle is 23°.

[0021] Preferably, the machine geometry deviation detector, the imaging system detector and the isocenter detector are all made of solid water.

[0022] Preferably, the cylindrical insert is made of fat equivalent, true water, bone equivalent or lung equivalent.

[0023] Preferably, the sphere in the isocenter detector is made of non-metallic material.

[0024] As can be seen above, in the multifunctional phantom of the present invention, since a machine geometry deviation detector, an imaging system detector and an isocenter detector are provided at the same time, the machine geometry deviation can be tested by the machine geometry deviation detector, and the accuracy of the laser light, the accuracy of the CT scanning layer thickness and the image quality can be tested by the imaging system detector, and the isocenter deviation can be tested by the isocenter detector, so that multiple measurement simulations of the radiotherapy equipment can be performed by using the above-mentioned multifunctional phantom, which can effectively meet the measurement requirements of various measurement indicators. Moreover, the above-mentioned multifunctional phantom in the present application has a simple overall structure, low cost, convenient use, easy operation, and accurate measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of the multifunctional phantom in an embodiment of the present invention.

[0026] Figure 2 Schematic diagram of the structure of a machine geometry deviation detector in an embodiment of the present invention.

[0027] Figure 3 Schematic diagram of the position of the metal marker in the embodiment of the present invention Figure 1 .

[0028] Figure 4 Schematic diagram of the position of the metal marker in the embodiment of the present invention Figure 2 .

[0029] Figure 5 Schematic diagram of the position of the metal marker in the embodiment of the present invention Figure 3 .

[0030] Figure 6 Schematic diagram of the position of the metal marker in the embodiment of the present invention Figure 4 .

[0031] Figure 7 Schematic diagram of the structure of the first cylinder in an embodiment of the present invention.

[0032] Figure 8 It is a side view of the first cylinder in the embodiment of the present invention.

[0033] Fig. 9 FIG. 4 is a schematic diagram of an image showing the deflection of a metal wire in an embodiment of the present invention.

[0034] Fig.10 It is a schematic diagram of an image of a metal wire when the mold body is placed at an angle in an embodiment of the present invention.

[0035] Fig.11 FIG. 4 is a schematic diagram of an image of a metal wire under normal conditions in an embodiment of the present invention.

[0036] Fig.12 Schematic diagram of the structure of the second cylinder in an embodiment of the present invention.

[0037] Fig.13 Schematic diagram of the structure of the isocenter detector in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0039] Figure 1 FIG. 1 is a schematic diagram of the structure of a multifunctional phantom in an embodiment of the present invention. Figures 1 to 13As shown, the multifunctional phantom in the embodiment of the present invention includes: a machine geometric deviation detector 11, an imaging system detector 12 and an isocenter detector 13;

[0040] A preset number of metal markers 111 are arranged in the machine geometric deviation detector 11, and each metal marker 111 is arranged at a preset position in the machine geometric deviation detector 11;

[0041] The image system detector 12 includes: a first cylinder 21 and a second cylinder 22; the bottom of the first cylinder 21 is connected to one side of the machine geometric deviation detector 11; the top of the first cylinder 21 is connected to the bottom of the second cylinder 22;

[0042] Two metal wire pairs are arranged in the first cylinder 21; each metal wire pair includes two metal wires 211 arranged opposite to each other; a preset angle is formed between the two metal wires in one metal wire pair and the bottom surface of the first cylinder 21; and the two metal wires in the other metal wire pair are parallel to the bottom surface of the first cylinder 21;

[0043] The second cylinder 22 is provided with four cylindrical plug-ins 221 having different densities;

[0044] The isocenter detector 13 is a cylinder, and the bottom of the isocenter detector 13 is connected to the second cylinder 22 of the imaging system detector 12 ; the top of the isocenter detector 13 is hemispherical, and a sphere 31 is embedded in the upper part of the isocenter detector 13 .

[0045] In the above-mentioned multifunctional phantom in the present application, since the machine geometry deviation detector 11, the imaging system detector 12 and the isocenter detector 13 are set at the same time, the machine geometry deviation (for example, the frame angle deviation △Φ, the rotation radius deviation △R, the rotation plane deviation △Z, the deviation △F of the center of the plate, the two flipping deviations △u and △v, the two angle rotations α and β of the plate, etc.) can be tested through the machine geometry deviation detector, and the accuracy of the laser light, the accuracy of the CT scanning layer thickness and the image quality can be tested through the imaging system detector. At the same time, the isocenter deviation can be tested through the isocenter detector, so that multiple measurement simulations of the radiotherapy equipment can be performed by using the above-mentioned multifunctional phantom, which can effectively meet the measurement requirements of various measurement indicators. Moreover, the above-mentioned multifunctional phantom in the present application has a simple overall structure, low cost, convenient use, easy operation, and accurate measurement results.

[0046] In addition, in the technical solution of the present application, the multifunctional phantom can be realized through a variety of specific implementation methods. The following will take several specific methods as examples to introduce the technical solution of the present application in detail.

[0047] For example, as an example, in a specific embodiment of the present application, the machine geometry deviation detector, the imaging system detector and the isocenter detector can all be made of solid water.

[0048] For another example, as an example, in a specific embodiment of the present application, the machine geometry deviation detector may be a cube or other suitable shapes.

[0049] In addition, in general, the larger the volume of the model, the more metal markers can be placed in the model, and the spacing between the metal markers on the projection pattern can be guaranteed to be sufficient for metal marker identification and positioning; moreover, the more metal markers there are, the more information can be extracted for simulation parameters, and the more accurate the calculation results are. However, the larger the volume of the model, the heavier the weight of the model will be, and the higher the manufacturing cost will be; moreover, the more metal markers there are, the greater the amount of calculation required for simulation calculations, and the longer the calculation time will be.

[0050] Therefore, in the technical solution of the present application, the number of metal markers in the machine geometric deviation detector and the specific position of each metal marker in the machine geometric deviation detector can be determined in advance according to the needs of the actual application scenario.

[0051] For example, as an example, Figure 2 As shown, in a specific embodiment of the present application, a plurality of grooves 112 are provided on the machine geometric deviation detector, and the metal markers 111 are respectively provided in the grooves 112 .

[0052] In addition, as an example, in a specific embodiment of the present application, the number of the metal markers may be 13, or may be other suitable numbers.

[0053] In addition, as an example, in a specific embodiment of the present application, the metal marker may be a steel bead.

[0054] For example, as an example, in a specific embodiment of the present application, the metal markers may be distributed in a non-uniform spiral in the machine geometry deviation detector.

[0055] In the technical solution of the present application, the above-mentioned metal markers (for example, 13 steel beads) can be distributed in a non-uniform spiral in the above-mentioned machine geometric deviation detector. The spatial distribution of the spiral with non-uniform spiral pitch can prevent the positions of the metal markers on the projection images at various angles from overlapping and can reduce the volume of the model as much as possible to facilitate identification and positioning.

[0056] For example, in a specific embodiment of the present application, assuming that the maximum imaging size of the electronic portal imaging system (EPID) is 37cm×37cm, considering the penumbra area, the portal opening size is preferably less than 35cm, and the phantom size (i.e., the side length of the phantom) is less than 20cm. Therefore, virtual cube models of various sizes from 10 to 25cm can be designed, and 9, 13 or 17 reference points are arranged in spiral trajectories on the surface of the cube. According to the selection results of the simulation experiment, a phantom with 13 metal markers inlaid on a cube with a side length of 18cm can meet the use requirements.

[0057] In addition, the size of the selected metal marker also needs to meet the condition that it can be clearly imaged on the EPID image. Therefore, the size of the metal marker can be determined based on this condition.

[0058] For example, as an example, in a specific embodiment of the present application, the diameter of a steel ball used as a metal marker may be 5 millimeters (mm).

[0059] In addition, as an example, Figure 2 to Figure 6 As shown, in a specific embodiment of the present application, when the geometric deviation detector is a cube with a side length of 180 mm, with the center of the cube as the origin of the three-dimensional space coordinate system (x, y, z) = (0, 0, 0), the specific coordinate values ​​of the 13 steel balls in the machine geometric deviation detector can be: (-15, 90, -90), (80, 90, 0), (-30, 90, 0), (65, 90, 90), (-45, 90, 90), (55, 0, 90), (-55, 0, 90), (45, -90, 90), (-65, -90, 90), (30, -90, 0), (-80, -90, 0), (15, -90, -90) and (0, 0, -90).

[0060] After the above-mentioned metal markers are arranged inside the above-mentioned machine geometric deviation detector, the machine geometric deviation can be tested accordingly through these metal markers.

[0061] For example, in the technical solution of the present application, the geometric position of each unit in the accelerator system can be defined as eight parameters in the coordinate system, namely:

[0062] (1) Three parameters related to the source: rack angle deviation △Φ, rotation radius deviation △R, rotation plane deviation △Z;

[0063] (2) Deviation of the center of the plate △F, two flip deviations △u and △v;

[0064] (3) The plate is rotated by two angles α and β.

[0065] The change of the above eight parameters will cause the coordinates of the 13 steel balls on the projection image to change. Therefore, the specific values ​​of the above eight parameters can be determined according to the coordinates of the 13 steel balls on the projection image.

[0066] Since the above-mentioned 8-parameter nonlinear optimization problem is difficult to solve directly using the coordinate deviations of the 13 steel balls, a hybrid optimization algorithm can be used. First, an exhaustive search is applied and possible solutions are compared to find the best 1000 parameter combination seeds for the simulated annealing algorithm. Each step in the simulated annealing algorithm replaces the current solution with a random "nearby" solution, whose probability depends on the difference between the corresponding function value and a global parameter called the annealing temperature. In this process, the annealing temperature is gradually reduced, and finally the progress converges to the best simulation result of the geometric parameters.

[0067] For example, specifically, the values ​​of the above eight parameters can be determined by the following steps:

[0068] Step 1: According to the current values ​​of the above 8 parameters, the coordinates of 13 steel balls on the projection image are obtained through simulation calculation;

[0069] Step 2: Identify the actual electronic portal imaging system (EPID) projection image of the phantom to obtain the actual coordinates of the 13 steel balls on the projection image;

[0070] Step 3: Compare the two coordinates to determine whether the coordinate difference between the two coordinates converges; if not, execute step 4; if converged, execute step 5;

[0071] Step 4: Update the values ​​of the above 8 parameters and return to step 1;

[0072] Step 5: Use the current values ​​of the eight parameters as the final values ​​of the eight parameters.

[0073] Therefore, the specific values ​​of the above eight parameters can be determined through the above steps.

[0074] In addition, as an example, in a specific embodiment of the present application, a connecting device is provided on one side of the machine geometry deviation detector; the connecting device is used to fix the machine geometry deviation detector on the treatment bed, so that the machine geometry deviation detector, imaging system detector and isocenter detector on the phantom can be suspended in the air; in addition, the machine geometry deviation detector can also be fixed to a preset position on the treatment bed through the connecting device, so that the positions of the machine geometry deviation detector, imaging system detector and isocenter detector relative to the treatment bed are fixed each time to maintain the measurement accuracy.

[0075] In addition, as an example, in a specific embodiment of the present application, the connecting device may be a snap-fit ​​structure, so that the machine geometry deviation detector can be easily fixed on the treatment bed.

[0076] In addition, as an example, in a specific embodiment of the present application, a leveling device is provided at the bottom of the machine geometric deviation detector; the leveling device is used to adjust the horizontality of the mold body.

[0077] Therefore, the horizontality of the mold body can be adjusted by the above-mentioned leveling device.

[0078] In addition, in the technical solution of the present application, the first cylinder in the imaging system detector can be used to test the accuracy of the laser light and the accuracy of the CT scanning layer thickness.

[0079] For example, the multifunctional phantom in the present application can be aligned with the laser lamp according to the central axis line, and then sent to the roller for central layer CT imaging. The imaging symmetry of the metal wire can show the offset of the laser lamp.

[0080] The vertical line of the laser light is deviated, deviating towards the gantry or the bed. The calculation formula for the deviation distance is: the distance from the midpoint of the wire to the central axis × 0.42.

[0081] For example, a metal wire can behave like Fig. 9 As shown, Fig. 9 The left figure in the figure shows the bias towards the rack, while Fig. 9 The right picture in the figure shows a biased bed.

[0082] If the wires in the image are not only asymmetrical but also have inconsistent lengths, it means that the phantom is placed at an angle, such as Fig.10 shown.

[0083] When the position of the phantom and the accuracy of the laser light are correct, the performance of the metal wire can be as follows: Fig.11 shown.

[0084] Therefore, the calculation formula of the CT scanning layer thickness can be: layer thickness = metal wire length × tanα, wherein α is the angle between the metal wire and the bottom surface of the first cylinder.

[0085] Therefore, in the technical solution of the present application, the size of the angle α between the two metal wires in a metal wire pair in the first cylinder and the bottom surface of the first cylinder can be predetermined according to the needs of the actual application scenario.

[0086] For example, as an example, in a specific embodiment of the present application, the preset angle α is 23°. Figure 8 shown.

[0087] In addition, in the technical solution of the present application, the second cylinder in the imaging system detector can be used to test the image quality.

[0088] For example, as an example, in a specific embodiment of the present application, since four cylindrical plug-ins with different densities are arranged in the second cylinder, the image quality can be analyzed by measuring the CT value accuracy and uniformity of the four cylindrical plug-in areas in the CT image.

[0089] In addition, in the technical solution of the present application, the distance between the cylindrical plug-in and the edge of the second cylinder can be predetermined according to the needs of the actual application scenario.

[0090] For example, as an example, in a specific embodiment of the present application, the distance between the cylindrical plug-in and the edge of the second cylinder is greater than 2 centimeters (cm), so that the edge effect can be avoided.

[0091] In addition, as an example, in a specific embodiment of the present application, the cylindrical plug-ins may be evenly distributed in the second cylinder.

[0092] In addition, as an example, in a specific embodiment of the present application, the cylindrical plug-in can be made of fat equivalent, real water, bone equivalent or lung equivalent according to the needs of the actual application scenario.

[0093] In addition, in the technical solution of the present application, an isocenter detector can be used to test the isocenter deviation.

[0094] For example, as an example, in a specific embodiment of the present application, the center of a sphere embedded in an isocenter detector can be identified on EPID imaging or CT image-guided imaging, and the coordinates of the center of the identified sphere can be compared with the pre-calibrated isocenters, so that the isocenter deviation can be analyzed.

[0095] In addition, as an example, in a specific embodiment of the present application, the sphere in the isocenter detector can be made of non-metallic material (for example, ceramic material), so as to effectively avoid metal artifacts during CT imaging.

[0096] In summary, in the technical solution of the present application, since a machine geometry deviation detector, an imaging system detector and an isocenter detector are provided at the same time, the machine geometry deviation can be tested by the machine geometry deviation detector, and the accuracy of the laser light, the accuracy of the CT scanning layer thickness and the image quality can be tested by the imaging system detector, and the isocenter deviation can be tested by the isocenter detector, so that multiple measurement simulations of the radiotherapy equipment can be performed by using the above-mentioned multifunctional phantom, which can effectively meet the measurement requirements of various measurement indicators. Moreover, the above-mentioned multifunctional phantom in the present application has a simple overall structure, low cost, convenient use, easy operation, and accurate measurement results.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multifunctional phantom, characterized in that: The multifunctional phantom includes: a machine geometry deviation detector, an imaging system detector and an isocenter detector; The machine geometry deviation detector is used to test the machine geometry deviation of the radiotherapy equipment; a plurality of metal markers are arranged in the machine geometry deviation detector, and each metal marker is arranged at a preset position in the machine geometry deviation detector; a plurality of grooves are arranged on the machine geometry deviation detector, and the metal markers are respectively arranged in the grooves; The imaging system detector comprises: a first cylinder and a second cylinder; the bottom of the first cylinder is connected to one side of the machine geometric deviation detector; the top of the first cylinder is connected to the bottom of the second cylinder; Two metal wire pairs are arranged in the first cylinder; each metal wire pair includes two metal wires arranged opposite to each other; a preset angle is formed between the two metal wires in one metal wire pair and the bottom surface of the first cylinder; and the two metal wires in the other metal wire pair are parallel to the bottom surface of the first cylinder; The second cylinder is provided with four cylindrical inserts having different densities; The isocenter detector is used to test the isocenter deviation of the radiotherapy equipment; the isocenter detector is a cylinder, and the bottom of the isocenter detector is connected to the second cylinder of the imaging system detector; the top of the isocenter detector is hemispherical, and a sphere is embedded in the upper part of the isocenter detector; Wherein, the plurality of metal markers are 13 steel beads; When the geometric deviation detector is a cube with a side length of 180 mm, with the center of the cube as the origin of the three-dimensional space coordinate system (x, y, z) = (0, 0, 0), the specific coordinate values ​​of the 13 steel balls in the machine geometric deviation detector are: (-15, 90, -90), (80, 90, 0), (-30, 90, 0), (65, 90, 90), (-45, 90, 90), (55, 0, 90), (-55, 0, 90), (45, -90, 90), (-65, -90, 90), (30, -90, 0), (-80, -90, 0), (15, -90, -90) and (0, 0, -90); The geometric positions of each unit in the accelerator system are defined as eight parameters in the coordinate system, and the specific values ​​of the eight parameters are determined according to the coordinates of the 13 steel balls on the projection image, so as to test the machine geometric deviation of the radiotherapy equipment; The eight parameters include: (1) Three parameters related to the source: frame angle deviation △Φ, rotation radius deviation △R, rotation plane deviation △Z; (2) Deviation of the center of the plate △F, two flip deviations △u and △v; (3) The plate is rotated by two angles α and β.

2. The multifunctional phantom according to claim 1, characterized in that: A connecting device is provided on one side of the machine geometric deviation detector; The connecting device is used to fix the machine geometry deviation detector on the treatment bed.

3. The multifunctional phantom according to claim 1, characterized in that: A leveling device is provided at the bottom of the machine geometric deviation detector; The leveling device is used to adjust the horizontality of the multifunctional mold body.

4. The multifunctional phantom according to claim 1, characterized in that: The preset angle is 23°.

5. The multifunctional phantom according to claim 1, characterized in that: The machine geometry deviation detector, the imaging system detector and the isocenter detector are all made of solid water.

6. The multifunctional phantom according to claim 1, characterized in that: The cylindrical insert is made of fat equivalent, real water, bone equivalent or lung equivalent.

7. The multifunctional phantom according to claim 1, characterized in that: The sphere in the isocenter detector is made of non-metallic material.

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