A displacement measuring device and method for a multi-leaf collimator

Abstract

The embodiment of the present specification provides a displacement measurement device and method for a multi-leaf collimator. The displacement measurement device comprises: a plurality of magnetic pieces, each magnetic piece being connected with a leaf of the multi-leaf collimator; a plurality of magnetoresistance sensors corresponding to the plurality of magnetic pieces respectively, each magnetic piece in the plurality of magnetic pieces being located between a leaf of the multi-leaf collimator and a magnetoresistance sensor in the plurality of magnetoresistance sensors; and a signal processing circuit connected with the plurality of magnetoresistance sensors.

Description

Technical Field

[0001] This invention relates to the field of displacement calculation technology, and in particular to a displacement measurement device and method for multi-leaf gratings. Background Technology

[0002] Multi-leaf collimators (MLCs) are widely used in collimated radiotherapy systems to project radiation beams. The principle of a radiotherapy system is to project a radiation beam collimated by an MLC onto the tumor, ensuring the projected area conforms to the shape of the tumor, killing tumor cells while avoiding radiation to surrounding healthy tissue. However, semiconductor devices in radiotherapy systems, such as displacement measuring devices for moving parts, experience a significant reduction in lifespan under radiation.

[0003] Therefore, it is desirable to provide a displacement measurement device and method for multi-leaf gratings. Summary of the Invention

[0004] One aspect of this application provides a displacement measurement device for a multi-leaf grating. The device includes: a plurality of magnetic elements, each magnetic element connected to one leaf of the multi-leaf grating; a plurality of magnetoresistive sensors corresponding to the plurality of magnetic elements, each magnetic element being located between one leaf of the multi-leaf grating and one of the magnetoresistive sensors; and a signal processing circuit connected to the plurality of magnetoresistive sensors.

[0005] In some embodiments, the plurality of magnetoresistive sensors are connected by a circuit board that extends in a direction perpendicular to the extension direction of each magnetic element.

[0006] In some embodiments, the multileaf grating is applied in a radiotherapy device, and the signal processing circuit is located outside the radiation area of ​​the radiation beam emitted by the radiotherapy device.

[0007] In some embodiments, the signal processing circuit is located outside the housing of the multileaf grating.

[0008] In some embodiments, the signal processing circuit includes: a signal processing module for preprocessing the signals generated by the plurality of magnetoresistive sensors to obtain a preprocessed signal; a sampling module for sampling the preprocessed signal to obtain a sampled signal; and a displacement calculation module for subdividing the sampled signal using an arctangent difference calculation algorithm to determine the displacement of the blade.

[0009] In some embodiments, the displacement calculation module includes a square wave conversion unit and an arctangent calculation unit. The square wave conversion unit is used to convert the sampled signal into a square wave signal; and the arctangent calculation unit is used to subdivide the sampled signal using an arctangent difference calculation algorithm to determine the relative displacement within the period of the square wave signal corresponding to the sampled signal.

[0010] Another aspect of this application provides a method for displacement measurement of a multi-leaf grating based on a displacement measuring device. The method includes: acquiring an initial signal related to the displacement of one leaf of the multi-leaf grating, collected by at least one of a plurality of magnetoresistive sensors; preprocessing the initial signal using a signal processing circuit to obtain a preprocessed signal; sampling the preprocessed signal using the signal processing circuit to obtain a sampled signal; and calculating the leaf displacement based on the sampled signal using the signal processing circuit.

[0011] In some embodiments, sampling the preprocessed signal through the signal processing circuit to obtain a sampled signal includes: sampling the preprocessed signal using an analog-to-digital converter with an accuracy greater than or equal to 16 bits and a speed greater than or equal to 2 Msps to obtain the sampled signal.

[0012] In some embodiments, calculating the blade displacement based on the sampled signal using the signal processing circuit includes: calculating the blade displacement based on the sampled signal using an arctangent difference algorithm.

[0013] In some embodiments, calculating the blade displacement based on the sampled signal using an arctangent difference algorithm includes: converting the sampled signal into a square wave signal and determining the number of displacement cycles based on the square wave signal; simultaneously, subdividing the sampled signal using the arctangent difference algorithm to determine the relative displacement within the period of the square wave signal corresponding to the sampled signal; and determining the blade displacement based on the relative displacement and the number of displacement cycles.

[0014] Another aspect of this application provides a computer-readable storage medium that stores computer instructions. When a computer reads the computer instructions in the storage medium, the computer executes the displacement measurement method as described above.

[0015] The displacement measuring device for multileaf gratings provided in this application embodiment uses magnetoresistive non-contact (e.g., a combination of magnetic components and magnetoresistive sensors) and relatively stationary magnetoresistive sensors to measure the displacement of multileaf gratings. This not only helps to improve the radiation lifetime of the displacement measuring device, but also has a relatively simple structure and long lifespan. Attached Figure Description

[0016] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0017] Figure 1 These are schematic diagrams illustrating application scenarios of exemplary radiotherapy systems according to some embodiments of this specification;

[0018] Figure 2 This is a schematic diagram of the structure of an exemplary multileaf grating according to some embodiments of this specification;

[0019] Figure 3 This is a schematic diagram of an exemplary multileaf grating displacement measuring device according to some embodiments of this specification;

[0020] Figure 4 These are schematic diagrams of the structure of exemplary magnetic components shown in some embodiments of this specification;

[0021] Figure 5 These are schematic diagrams of the structure of exemplary magnetic components shown in other embodiments of this specification;

[0022] Figure 6A This is a schematic diagram of the circuit structure of an exemplary magnetoresistive sensor according to some embodiments of this specification;

[0023] Figure 6B These are schematic diagrams of exemplary sine and cosine curves according to some embodiments of this specification;

[0024] Figure 7 This is a schematic diagram of the structure of an exemplary signal processing circuit shown in some embodiments of this specification;

[0025] Figure 8 This is a flowchart of an exemplary multileaf grating displacement measurement method according to some embodiments of this specification. Detailed Implementation

[0026] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0027] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0028] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0029] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0030] Figure 1 This is a schematic diagram illustrating an application scenario of an exemplary radiotherapy system according to some embodiments of this specification.

[0031] like Figure 1 As shown, in some embodiments, the radiotherapy system 100 may include a radiotherapy device 110, a processing device 120, one or more terminals 130, a storage device 140, and a network 150. In some embodiments, the radiotherapy device 110, processing device 120, terminal 130, and / or storage device 140 may be connected to and / or communicate with each other via wireless connections, wired connections, or a combination thereof. In some embodiments, the connections in the radiotherapy system 100 may be varied. This is merely an example. Figure 1 As shown, the radiotherapy device 110 can be connected to the processing device 120 via network 150. Alternatively, the radiotherapy device 110 can be directly connected to the processing device 120. Another example is that the storage device 140 can be connected to the processing device 120 via network 150 or directly to the processing device 120. Yet another example is that the terminal 130 can be connected to the processing device 120 via network 150 or directly connected to the processing device 120 (e.g.,...). Figure 1 (As shown by the double-headed dashed arrow in the middle), it is connected to the radiotherapy device 110 either directly or via network 150. Alternatively, terminal 130 may be omitted.

[0032] The radiotherapy device 110 can perform radiotherapy on at least a portion of a target object. In some embodiments, the radiotherapy device 110 may include a single-modal device, such as an X-ray therapy device, a Co-60 teletherapy device, a medical electron accelerator, etc. In some embodiments, the radiotherapy device 110 may be a multimodal (e.g., bimodal) device to acquire medical images related to at least a portion of the target object and to perform radiotherapy on at least a portion of the target object. The target object may be biological or non-biological. For example, the target object may include a patient, an artificial object, etc. Another example is that the target object may include a specific part, organ, and / or tissue of a patient. For example, the target object may include the head, neck, chest, heart, stomach, blood vessels, soft tissue, tumor, nodule, etc., or combinations thereof. In some embodiments, the target object may include a region of interest (ROI), such as a tumor, a node, etc.

[0033] In some embodiments, the radiotherapy device 110 may include a gantry connected to a treatment head. In some embodiments, the treatment head may include a radiation source 112 and a multi-leaf collimators (MLCs) 114. The radiation source 112 emits a radiation beam toward a target object. The MLC 114 is used to collimate the radiation beam emitted from the radiation source 112 to form a radiation region of a specific shape. In some embodiments, the MLC 114 may include multiple leaves to adjust the radiation region. The multiple leaves may be driven by one or more drive components (e.g., an electric motor) to move to a specific position to form a radiation region of a specific shape. In some embodiments, the motion displacement of the multi-leaf collimators can be determined by a displacement measuring device to move and position the multi-leaf collimators so that the radiation region forms the desired shape. The more accurate the displacement measurement of the multi-leaf collimators, the more accurate the motion control of the multi-leaf collimators, resulting in a more suitable radiation region (e.g., matching the patient's tumor area).

[0034] Processing device 120 can process data and / or information obtained from radiotherapy device 110, storage device 140, and / or (multiple) terminals 130. For example, processing device 120 can determine the blade displacement in MLC 114 based on a displacement measuring device. In some embodiments, processing device 120 can be integrated into the displacement measuring device. For example, processing device 120 can be a signal processing circuit in the displacement measuring device.

[0035] Terminal 130 can connect to and / or communicate with radiotherapy device 110, processing device 120, and / or storage device 140. For example, terminal 130 can acquire processed images from processing device 120. As another example, terminal 130 can acquire image data from radiotherapy device 110 and transmit the image data to processing device 120 for processing. In some embodiments, terminal 130 may include mobile device 131, tablet computer 132, laptop computer 133, etc., or any combination thereof.

[0036] Storage device 140 may store data and / or instructions. In some embodiments, storage device 140 may store data obtained from radiotherapy device 110, processing device 120, and / or terminal 130. In some embodiments, storage device 140 may store data and / or instructions that processing device 120 may execute or be used to execute the exemplary methods described herein. In some embodiments, storage device 140 may include a mass storage device, a removable storage device, a volatile read-write storage device, a read-only storage device (ROM), etc., or any combination thereof. In some embodiments, storage device 140 may be implemented on a cloud platform.

[0037] In some embodiments, storage device 140 may be connected to network 150 to communicate with at least one component of radiotherapy system 100 (e.g., processing device 120, terminal 130). At least one component of radiotherapy system 100 may access data or instructions stored in storage device 140 via network 150.

[0038] Network 150 includes any suitable network that can facilitate information and / or data exchange within the radiotherapy system 100. In some embodiments, at least one component of the radiotherapy system 100 (e.g., radiotherapy device 110, processing device 120, terminal 130, storage device 140, etc.) can send information and / or data to at least one other component of the radiotherapy system 100 via network 150. For example, processing device 120 can obtain image data from radiotherapy device 110 via network 150. As another example, processing device 120 can obtain user instructions from terminal 130 via network 150. In some embodiments, network 150 can be any type of wired or wireless network, or a combination thereof. In some embodiments, network 150 can include at least one network access point. For example, network 150 can include at least one wired or wireless network access point, such as a base station and / or internet exchange point, through which at least one component of the radiotherapy system 100 can connect to network 150 to exchange data and / or information.

[0039] Figure 2This is a schematic diagram of the structure of an exemplary multileaf grating according to some embodiments of this specification.

[0040] like Figure 2 As shown, a multi-leaf grating (MLC) is a mechanical moving component in a radiotherapy device used to generate a conformal radiation zone. In some embodiments, the MLC 114 may include a blade assembly 220, a housing 240, and a drive assembly 260. In some embodiments, the blade assembly 220 may include a plurality of blades (e.g., blades 220-1, 220-2, 220-i, ..., 220-n, etc.), each blade being independently movable within the housing 240, for example, moving towards or away from the center of the radiation zone. The center of the radiation zone may refer to the geometric center of the radiation zone formed by the plurality of blades. In some embodiments, the drive assembly 260 may include a plurality of motors (e.g., motors 260-1, 260-2, ..., 260-i, ..., 260-n, etc.). The plurality of motors may be associated with the plurality of blades (e.g., blades 220-1, 220-2, ..., 220-i, ..., 220-n, etc.). In some embodiments, each of the plurality of motors can drive a corresponding blade of the plurality of blades to move independently within the housing 240 to form a radiation region. In some embodiments, the motors can drive each blade of the plurality of blades to move away from the center of the radiation region. In some embodiments, the motors can drive each blade of the plurality of blades to move towards the center of the radiation region.

[0041] Figure 3 This is a schematic diagram of an exemplary multileaf grating displacement measuring device according to some embodiments of this specification.

[0042] like Figure 3 As shown, in some embodiments, the displacement measuring device 300 may include a magnetic component 310, a magnetoresistive sensor 320, and a signal processing circuit 330.

[0043] In some embodiments, the magnetic element may include a magnetic grating. A magnetic grating, also known as a magnetic scale, is a device that uses electromagnetic methods to record the number of magnetic waves. For example, based on its structure, it can be divided into linear magnetic gratings (such as magnetic grating strip 310-i) and circular magnetic gratings. In some embodiments, the magnetic grating can be used to measure linear displacement and / or angular displacement.

[0044] In some embodiments, the magnetic element 310 may include multiple magnetic elements, such as magnetic grating strips 310-1, 310-2, 310-i, ..., 310-n, etc. In some embodiments, each magnetic element may be physically connected to one leaf (e.g., leaf 220-1, leaf 220-2, leaf 220-i, ..., leaf 220-n, etc.) of a multi-leaf grating (e.g., multi-leaf grating 114) and move with the leaf. The number of leaves of the multi-leaf grating is the same as the number of magnetic elements in the displacement measuring device. The extension direction of the magnetic element (i.e., the major axis direction, such as the X-axis direction shown in the figure) is the same as the direction of movement of the leaf. In some embodiments, the magnetic element connected to the leaf may be disposed above the leaf, for example, physically connected to the upper surface of the leaf. In some embodiments, the magnetic element connected to the leaf may be disposed below the leaf, for example, physically connected to the lower surface of the leaf. As described herein, when a multi-leaf grating is applied in a radiotherapy device (such as radiotherapy device 110), the upper part of the leaf can refer to the direction of the side closer to the radiation source (e.g., the upper surface); the lower part of the leaf can refer to the direction of the side farther from the radiation source (e.g., the lower surface). For example, Figure 4 As shown, the magnetic strip 310-i can be fixed to the lower surface of the blade 210-i, and can be in a direction parallel to the blade's movement direction.

[0045] In some embodiments, the magnetic component may include a permanent magnet formed by multiple S / N pole pairs connected in series. The N and S poles in the S / N pole pairs may have the same or different lengths. In some embodiments, the lengths of the N and / or S poles may be 3 mm, 2 mm, 1 mm, etc. For example... Figure 5 As shown, the magnetic components (e.g., magnetic grating strips 310-1, 310-2, 310-i, ..., 310-n, etc.) can be composed of multiple pole pairs, each with a length of 2mm for both the N and S poles. The length of the magnetic poles is related to the resolution; the shorter the pole length, the higher the resolution, but the greater the manufacturing difficulty. Using magnetic grating strips composed of pole pairs connected in series with a total length of 2mm + 2mm = 4mm can balance resolution and manufacturing difficulty, relatively reducing manufacturing difficulty while ensuring resolution.

[0046] In some embodiments, the length of the magnetic element can be flexibly selected. For example, as... Figure 4 As shown, the length of the magnetic grating strip 310-i can be the same as the length of the blade 220-i of the multi-leaf grating, which can improve the accuracy of displacement determination. Alternatively, the length of the magnetic grating strip 310-i can be less than the length of the blade 220-i.

[0047] In some embodiments, the magnetoresistive sensor 320 may include multiple magnetoresistive sensors corresponding to multiple magnetic elements, such as magnetoresistive sensor 320-1, magnetoresistive sensor 320-2, magnetoresistive sensor 320-i, ..., magnetoresistive sensor 320-n, etc.

[0048] A magnetoresistive sensor is a device that converts changes in the magnetic properties of a sensitive element caused by factors such as magnetic fields, current, and temperature into electrical signals to detect corresponding physical quantities. Magnetoresistive sensors are made based on the magnetoresistive effect of magnetic materials. Magnetic materials (such as permalloy) are anisotropic; when magnetized, their magnetization direction depends on the material's easy magnetization axis, its shape, and the direction of the magnetizing magnetic field. When a current I is passed through a magnetic material (such as a strip of permalloy), the material's resistance depends on the angle between the current direction and the magnetization direction. If a magnetic field B (the measured magnetic field) is applied to the material, the original magnetization direction will rotate. If the magnetization direction changes to be perpendicular to the current direction, the material's resistance will decrease; if the magnetization direction changes to be parallel to the current direction, the material's resistance will increase.

[0049] In some embodiments, the magnetoresistive sensor 320 may include a Wheatstone bridge circuit. In some embodiments, the magnetoresistive sensor 320 may include two Wheatstone bridges that generate sine and cosine signals respectively, so as to determine the direction of movement of the magnetic component by the phase difference between the signals output by the two Wheatstone bridges. For example... Figure 6A As shown, each dashed box represents a Wheatstone bridge, where G is a galvanometer. Each magnetoresistive sensor can include two sets of Wheatstone bridge circuits arranged one after the other, 1 mm apart, with a phase difference of π / 2, to generate sine and cosine signals respectively. Figure 6B The diagram shows the sine curve Y = sin X and the cosine curve Y = cos X. The direction of motion of the magnetic component can be determined by the phase lead or lag of the sine and cosine signals generated by the two Wheatstone bridges. For example, combined with... Figure 3 as well as Figure 6B As shown, when the magnetic component moves to the left, that is... Figure 3 As shown, when the magnetic component moves away from the X-axis, the phase of the sinusoidal signal Y = sin X will lead the phase of the cosine signal Y = cos X by 90°; when the magnetic component moves to the right, i.e. Figure 3 As shown, when moving towards the X-axis, the phase of the sine signal leads the phase of the cosine signal by less than 90°, meaning the phase difference between the sine and cosine signals is less than 90°. In some embodiments, the Wheatstone bridge circuit can consist of multiple resistors, for example... Figure 6AAs shown, a Wheatstone bridge circuit can include resistors 323-1 to 323-4 or resistors 323-5 to 323-8. When a magnetic field B is applied to the magnetic material of a magnetoresistive sensor, under the action of the measured magnetic field B, the resistance values ​​of two resistors located at opposite positions in the bridge (such as a Wheatstone bridge) increase, while the resistance values ​​of the other two resistors decrease. The displacement change of the magnetic component can be calculated by utilizing the resistance change generated along the current direction due to the magnetoresistive effect.

[0050] The magnetoresistive effect can be related to material properties and geometry. For example, the greater the mobility of a material, the more significant the magnetoresistive effect; the smaller the length or width of the element, the greater the magnetoresistive effect. In some embodiments, the magnetoresistive sensor can employ sensors with different technologies, such as Hall effect sensors, anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, tunneling magnetoresistive (TMR) sensors, or any combination thereof. For example, a magnetoresistive sensor based on TMR technology can be selected, with a resolution of up to 100 mV / V / Oe, thereby maximizing the signal generated on the sensor side.

[0051] In some embodiments, each magnetic element may be located between one leaf of a multi-leaf grating and one magnetoresistive sensor among a plurality of magnetoresistive sensors. For example, when the magnetic element connected to the leaf is disposed below the leaf, each magnetoresistive sensor may be located below the corresponding magnetic element. As another example, when the magnetic element connected to the leaf is disposed above the leaf, each magnetoresistive sensor may be located above the corresponding magnetic element.

[0052] For example Figure 4 As shown, the magnetic grating strip 310-i can be located between the blade 210-i and the magnetoresistive sensor 320-i. In some embodiments, each magnetic element can correspond one-to-one with a grating blade and a magnetoresistive sensor. In some embodiments, the magnetoresistive sensor and the magnetic element can be non-contact, for example... Figure 4 As shown in the figure. In some embodiments, the displacement measuring device 300 may further include a circuit board 340. The circuit board 340 can transmit the signal collected by the magnetoresistive sensor 320 to the signal processing circuit 330. In some embodiments, multiple magnetoresistive sensors can be connected through the circuit board 340. For example, magnetoresistive sensors 320-1, 320-2, 320-i, ..., 320-n can be uniformly arranged and fixedly connected on the circuit board 340. In some embodiments, the circuit board 340 can extend in a direction perpendicular to the extension direction of each magnetic element. For example... Figure 3As shown, the circuit board 340 can extend along a direction Y perpendicular to the extension direction X of each magnetic grating strip. In some embodiments, the circuit board 340 can include any shape such as a strip, circle, or ellipse. In some embodiments, the circuit board 340 can be fixed to the housing (e.g., housing 240) of the multi-leaf grating by structural components. In some embodiments, the circuit board 340 may include only the magnetoresistive sensor 320. By mounting the magnetoresistive sensor on the circuit board without mounting other processing circuitry, the radiation resistance of the circuit board can be improved.

[0053] The signal processing circuit 330 can be connected to multiple magnetoresistive sensors 320 to receive signals generated by the multiple magnetoresistive sensors 320 and determine the displacement of the multi-leaf grating blades based on the received signals. For example, the signal processing circuit 330 can be connected to a circuit board 340 that connects multiple magnetoresistive sensors in the form of wires to receive signals generated by at least one of the multiple magnetoresistive sensors 320.

[0054] When a multi-leaf grating is applied in a radiotherapy device (such as radiotherapy device 110), the signal processing circuit 330 can be located outside the radiation area of ​​the radiation beam emitted by the radiotherapy device, for example, outside the radiation area of ​​the radiation beam emitted by the radiation source 112. Figure 1 Outside the area where the arrow represents the radiation beam emitted by radiation source 112. In some embodiments, the signal processing circuit 330 may be located outside the housing (e.g., housing 240) of the multileaf grating. In some embodiments, the signal processing circuit 330 may be located inside the housing (e.g., housing 240) of the multileaf grating.

[0055] In some embodiments, a shielding element may be provided around the signal processing circuit 330 to reduce radiation transmitted to the signal processing circuit 330. For example Figure 3 As shown, a shielding plate can be placed between the signal processing circuit 330 and the circuit board 340 to shield the signal processing circuit 330 from radiation. Alternatively, the signal processing circuit 330 can be placed within a shielding component. The shielding component may consist of a material that absorbs radiation, such as a metal like lead.

[0056] In some embodiments, the signal processing circuit 330 may include a signal processing module, a sampling module, and a displacement calculation module. For example... Figure 7 As shown, the signal processing circuit 330 may include a signal processing module 331, a sampling module 333, and a displacement calculation module 335.

[0057] In some embodiments, the signal processing module 331 can be used to preprocess signals generated by multiple magnetoresistive sensors to obtain a preprocessed signal. In some embodiments, the signal processing module 331 may include at least one of a filter and an amplifier. For example, the filter may include a low-pass filter, a band-pass filter, etc. Similarly, the amplifier may include a differential operational amplifier, a differential operational amplifier, etc.

[0058] In some embodiments, the sampling module 333 can be used to sample the preprocessed signal to obtain a sampled signal. In some embodiments, the sampling module 333 may include an analog-to-digital converter (ADC), such as a 16-bit 2Msps high-precision high-speed analog-to-digital converter.

[0059] In some embodiments, the displacement calculation module 335 can be used to subdivide the sampled signal using an arctangent difference calculation algorithm to determine the displacement of the blade.

[0060] In some embodiments, the displacement calculation module 335 may further include a square wave conversion unit 335-1 and an arctangent calculation unit 335-2. The square wave conversion unit 335-1 can be used to convert the sampled signal into a corresponding square wave signal. The arctangent calculation unit 335-2 can be used to subdivide the sampled signal using an arctangent difference calculation algorithm to determine the relative displacement within the period of the square wave signal corresponding to the sampled signal (i.e., the relative displacement within the period of the magnetic component). Further, the displacement calculation module 335 can determine the blade displacement based on the displacement period number and the relative displacement.

[0061] As an example only, when one of the multiple motors 260-i of the multi-leaf grating 114 drives the corresponding blade 220-i to move towards or away from the center of the radiation region (i.e., along the axial direction, for example, towards or away from the X-axis direction), the magnetic grating strip 310-i connected to the blade 220-i also moves axially. The magnetic field strength at the location of the magnetoresistive sensor 320-i directly below the magnetic grating strip 310-i exhibits a sinusoidal or cosine curve variation. The Wheatstone bridges of two of the magnetoresistive sensors 320-i generate corresponding sinusoidal and cosine signals, respectively. The magnetoresistive sensor 320-i transmits the generated signals through... The signal is transmitted via wire to signal processing circuit 330. Signal processing module 331 in signal processing circuit 330 filters and amplifies the received signal to obtain a pre-processed signal. Sampling module 333 uses an analog-to-digital converter to sample the pre-processed signal, converting the sine and cosine analog signals into corresponding digital signals (i.e., sampled signals), and then transmits the digital signals to displacement calculation module 335. Displacement calculation module 335 uses an arctangent difference algorithm to subdivide the sampled signal, and combines this with the signal period before subdivision and the size of magnetic stripe 310-i to calculate the relative displacement of the magnetic stripe, and thus the displacement of blade 220-i. For more information on blade displacement calculation, please refer to [link to relevant documentation]. Figure 8 Its detailed description is omitted here.

[0062] Figure 8 This is a flowchart of an exemplary multileaf grating displacement measurement method according to some embodiments of this specification.

[0063] Step 810: Obtain an initial signal related to the displacement of one leaf in a multi-leaf grating, acquired by at least one of the multiple magnetoresistive sensors.

[0064] The initial signal can reflect the change in magnetic field strength of the magnetoresistive sensor caused by the movement of the magnetic component. In some embodiments, the initial signal may include a sine signal and / or a cosine signal. In some embodiments, the frequency of the initial signal may not exceed 10 Hz. For example, the frequency of the initial signal is 5 Hz or 8 Hz. In some embodiments, an initial signal related to the displacement of one leaf of the multi-leaf grating, acquired by at least one magnetoresistive sensor among a plurality of magnetoresistive sensors, can be obtained at the start, during, or end of the movement of the multi-leaf grating. For example, when the magnetic component moves axially with the leaf of the multi-leaf grating, sine and cosine signals generated by one or more magnetoresistive sensors among a plurality of magnetoresistive sensors corresponding to the plurality of magnetic components can be acquired.

[0065] In some embodiments, the magnetoresistive sensor can transmit the acquired initial signal to the signal processing circuit via a circuit board (e.g., circuit board 340) and / or wires. For example, a magnetoresistive sensor composed of two sets of Wheatstone bridge circuits with a phase difference of π / 2 can obtain two sets of analog signals with a phase difference of π / 2 and transmit them to the signal processing circuit 330.

[0066] Step 820: The initial signal is preprocessed by the signal processing circuit to obtain the preprocessed signal.

[0067] In some embodiments, preprocessing may include at least one of filtering and amplification operations. For example, a signal processing circuit (such as signal processing module 331) may amplify the initial sine and cosine signals separately using an amplifier, amplify the signals to the volt level, and then filter them using a low-pass filter.

[0068] In some embodiments, the amplifier may include one or any combination of a differential operational amplifier, a differential operational amplifier, or other types of amplifiers.

[0069] In some embodiments, the cutoff frequency of the low-pass filter can be set to a level slightly higher than the frequency of the initial signal, such as 9 Hz or 10 Hz. In some embodiments, the filtering parameters (e.g., cutoff frequency) of the filter can be determined based on the response time of the displacement detection device and / or the radiotherapy system. For example, the faster the system response time, the higher the cutoff frequency of the low-pass filter.

[0070] In some embodiments, if the preprocessed signal does not meet the requirements, it can be amplified again. For example, the signal strength may be weakened after low-pass filtering, and a subsequent amplification circuit can be used to adjust the filtered signal so that the signal variation amplitude covers the input range of the analog-to-digital converter. In some embodiments, the subsequent amplification circuit can be used for signal compensation. For example, the subsequent amplification circuit may include an operational amplifier and a non-inverting amplifier. Alternatively, the subsequent amplification circuit may use the same amplifier as the one used to amplify the initial signal.

[0071] When measuring blade displacement using a magnetoresistive displacement measuring device, the signal generated by the magnetoresistive sensor is relatively weak due to the non-contact nature of the sensor with the blade. To further improve the accuracy of multi-leaf grating displacement measurement, the signal processing circuit is further separated from the magnetoresistive sensor, making the initial signal received by the signal processing circuit even weaker. This application enhances the signal strength by performing preprocessing operations such as filtering and amplification on the initial signal, thereby improving the accuracy of sampling and processing.

[0072] Step 830: The preprocessed signal is sampled by the signal processing circuit to obtain the sampled signal.

[0073] In some embodiments, the signal processing circuit (e.g., sampling module 333) can sample the preprocessed signal using an analog-to-digital converter (ADC) to obtain a sampled signal. As an example only, the ADC can convert the preprocessed signal by sampling the input analog signal at specified time intervals, approximating the original continuously changing amplitude values ​​with a finite number of amplitude values, thus transforming the continuous amplitude of the analog signal into a finite number of discrete values ​​with certain intervals; then, these discrete values ​​are represented using binary numbers, and finally converted into binary or multi-valued digital signals. For example, the digital signals converted from the signals of the two Wheatstone bridges of a magnetoresistive sensor can be denoted as Vsinθ and Vcosθ, respectively, where V represents the supply voltage of the Wheatstone bridges.

[0074] In some embodiments, the ADC can be an analog-to-digital converter (ADC) with an accuracy of 16 bits or more and a speed of 2 Msps or more, for example, a 16-bit 2 Msps ADC. Here, 16 bits means the ADC can theoretically support a maximum subdivision of 2 to the power of 16, or 65,536 subdivisions; 2 Msps means a sampling rate of 2 MHz, or 2 million samples per second. In some embodiments, the ADC can be determined based on displacement measurement requirements (e.g., resolution). For example, to achieve good accuracy, resolution, and response speed simultaneously. For example, to achieve a resolution of 1 μm, 4000 subdivisions are needed, resulting in a resolution of 4 mm / 4000 = 1 μm, thus ensuring 1 μm resolution while maintaining a fast system response speed. The selected ADC needs to support 4000 subdivisions. For example, a 16-bit 2 Msps high-precision, high-speed ADC.

[0075] Step 840: Calculate the blade displacement using a signal processing circuit based on the sampled signal.

[0076] In some embodiments, the signal processing circuit (e.g., displacement calculation module 335) can calculate the blade displacement based on the sampled signal using an arctangent difference algorithm. For example, the displacement calculation module 335 can determine the number of displacement cycles based on the sampled signal; calculate the relative displacement of the magnetic component corresponding to the blade within a cycle using an arctangent difference algorithm; and determine the blade displacement based on the relative displacement of the magnetic component corresponding to the blade within a single cycle and the number of displacement cycles.

[0077] In some embodiments, the signal processing circuit (e.g., displacement calculation module 335) can convert the sampled signal into a square wave signal and determine the number of displacement cycles based on the square wave signal; at the same time, it can subdivide the sampled signal using an arctangent difference calculation algorithm, calculate the relative displacement within the period of the square wave signal corresponding to the sampled signal (i.e., the relative displacement within the period of the magnetic component corresponding to the blade); and determine the blade displacement based on the relative displacement and the number of displacement cycles.

[0078] In some embodiments, the values ​​of the sampled signal at different times can be compared with a threshold. When the value of the sampled signal is greater than the threshold at a certain time, the value corresponding to that time can be set to a first preset value (e.g., 1). When the value of the sampled signal is less than the threshold at a certain time, the value corresponding to that time can be set to a second preset value (e.g., 0), thereby converting the sampled signal (e.g., a sine signal or a cosine signal) into a square wave signal.

[0079] As an example only, the square wave conversion unit 335-1 in the signal processing circuit can convert the received sinusoidal signal sinθ (or Vsinθ) from the magnetoresistive sensor into a signal with the magnetic field strength of the magnetic field strength. In comparison, when When the square wave conversion unit 335-1 outputs signal A as 1, then the square wave conversion unit 335-1 can output signal A as 1; when When the signal is 0, the square wave conversion unit 335-1 can output signal A as 0; otherwise (e.g., The square wave conversion unit 335-1 can output a signal A that is the same as sinθ (or Vsinθ), thus obtaining a square wave signal A corresponding to the sine signal; it can also convert the received cosine signal cosθ (or Vcosθ) from the magnetoresistive sensor with... In comparison, when When the square wave conversion unit 335-1 outputs signal B as 1, then the square wave conversion unit 335-1 can output signal B as 1; when When the signal is 0, the square wave conversion unit 335-1 can output signal B as 0; otherwise (e.g., The square wave conversion unit 335-1 can output a signal B that is the same as cosθ (or Vcosθ), thereby obtaining a square wave signal B corresponding to the cosine signal.

[0080] In some embodiments, the direction of motion of the magnetic component can be determined by the phase of square wave signals A and B. For example, when the phase of signal A leads that of signal B, it can be assumed that the magnetic component is moving to the left (i.e., moving along the center away from the radiation region, for example, ...). Figure 3 If the magnetic component moves along the positive X-axis, it moves to the right (i.e., towards the center of the radiation region). Figure 3 (Moves in the opposite direction along the X-axis).

[0081] In some embodiments, the signal processing circuit (e.g., displacement calculation module 335) can determine the number of displacement cycles based on the number of rising edges (or falling edges) of the sampled signal or square wave signal (e.g., square wave signal A or B). The number of displacement cycles refers to the number of cycles of the sampled signal (or square wave signal) during the entire motion process of the magnetic component from the initial moment to the current moment. For example, the signal processing circuit can determine the number of rising edges of square wave signal A as the number of displacement cycles A. count The number of rising edges of the square wave signal B is determined as the number of cycles B through which the displacement passes. count .

[0082] In some embodiments, the signal processing circuit (e.g., displacement calculation module 335) can calculate the relative displacement of the magnetic component corresponding to the blade within a period using an arctangent difference calculation algorithm. For example, the arctangent calculation unit 335-2 can be based on the formula: θ=arctan 2(sinθ, cosθ) (1) Calculate the angular displacement θ within the period of the square wave signal corresponding to the sampled signal, and then convert it to obtain the linear displacement X within the period of the magnetic component, i.e., X = (2 / π)θ. To calculate the displacement of the magnetic component throughout its entire motion from the initial moment to the current moment, it is necessary to calculate the number of displacement periods (i.e., how many cycles the magnetic component has moved through) and the displacement amount within the current period. The linear displacement X within the period can refer to the displacement of the magnetic component from the beginning of the current motion cycle to the current moment within the current cycle.

[0083] In some embodiments, the signal processing circuit can determine the blade displacement based on the relative displacement of the magnetic component within a period and the number of displacement periods. For example, the displacement calculation module 335 can use the obtained linear displacement X within a period plus the displacement of the whole period to calculate the magnetic component displacement D of the entire motion process. The magnetic component displacement is the displacement of the corresponding blade, as shown in formula (2): D = A count (or B) count )*L+X (2), Where L represents the displacement of the magnetic component within a single complete cycle. The displacement within all complete cycles (i.e., the total cycle displacement) equals the number of displacement cycles, A. count (or B) count Multiply by the displacement L within a single complete cycle. In some embodiments, the displacement within a single complete cycle may be equal to the length of a single magnetic pole pair of the magnetic element (e.g., L equals the total length of the magnetic pole pairs).

[0084] The method of interpolating and subdividing digital signals after ADC sampling allows for flexible resolution selection. For example, if the ADC sampling supports 6000 subdivisions, the subdivision number can be set to 4000 subdivisions, and the resolution can be set to 1μm. Alternatively, if the ADC sampling supports 6000 subdivisions, the subdivision number can be set to 5000 subdivisions, and the resolution can be set to 1μm.

[0085] In some embodiments, the blade displacement velocity can be obtained based on the blade displacement. For example, timing can be started simultaneously with the displacement measurement to obtain time T in real time, and the blade displacement velocity can be calculated according to formula (3): V = D / T (3).

[0086] It should be noted that the above description of process 800 is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to process 800 under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0087] The displacement measuring device or method provided in the above embodiments of this specification (1) uses a relatively stationary magnetoresistive sensor to detect the magnetic field of linear motion, and the signal processing circuit is far away from the magnetic field region (radiation region), which is beneficial to improve the radiation life of the displacement measuring device; (2) uses a combination of hardware and software to process the signal, for example, using ADC and arctangent difference subdivision algorithm, it is easier to perform interpolation subdivision according to the usage environment, and the resolution can be flexibly selected; (3) uses a magnetoresistive non-contact (e.g., magnetic components and magnetoresistive sensors combined) detection scheme for displacement measurement, which has a relatively simple structure and long life; (4) after detecting the magnetoresistive change signal, the signal strength can be improved by amplification and filtering, thereby improving the accuracy of displacement detection; (5) using a magnetoresistive sensor with strong radiation resistance, the circuit under strong radiation can be greatly simplified, the failure probability can be reduced, and the reliability of motion control components in the radiotherapy system can be improved.

[0088] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0089] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0090] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0091] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0092] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0093] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0094] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A displacement measuring device for a multi-leaf grating, wherein the multi-leaf grating is used in a radiotherapy device, characterized in that, include: Multiple magnetic elements, each magnetic element being connected to one leaf of the multi-leaf grating; A plurality of magnetoresistive sensors corresponding to the plurality of magnetic elements, wherein each of the plurality of magnetic elements is located between a leaf of the multi-leaf grating and a magnetoresistive sensor among the plurality of magnetoresistive sensors; as well as A signal processing circuit is connected in communication with the plurality of magnetoresistive sensors via a circuit board to determine the displacement of the blade based on the signals collected by the magnetoresistive sensors. The plurality of magnetoresistive sensors are connected via the circuit board and are mounted on the circuit board; the signal processing circuit is not mounted on the circuit board and is located outside the radiation area of ​​the radiation beam emitted by the radiotherapy device; the circuit board is configured to transmit the signals collected by the plurality of magnetoresistive sensors to the signal processing circuit.

2. The apparatus according to claim 1, characterized in that, The circuit board extends in a direction perpendicular to the extension direction of each magnetic element.

3. The apparatus according to claim 1, characterized in that, The signal processing circuit is located outside the housing of the multi-leaf grating.

4. The apparatus according to claim 1, characterized in that, The signal processing circuit includes: The signal processing module is used to preprocess the signals generated by the plurality of magnetoresistive sensors to obtain preprocessed signals; A sampling module is used to sample the preprocessed signal to obtain a sampled signal; and The displacement calculation module is used to subdivide the sampled signal using an arctangent difference calculation algorithm to determine the displacement of the blade.

5. The apparatus according to claim 4, characterized in that, The displacement calculation module includes a square wave conversion unit and an arctangent calculation unit. The square wave conversion unit is used to convert the sampled signal into a square wave signal; and The arctangent calculation unit is used to subdivide the sampled signal using an arctangent difference calculation algorithm to determine the relative displacement within the period of the square wave signal corresponding to the sampled signal.

6. A method for displacement measurement of a multi-leaf grating based on a displacement measuring device, wherein the multi-leaf grating is applied in a radiotherapy device, the displacement measuring device comprising a plurality of magnetic components, a plurality of magnetoresistive sensors corresponding to the plurality of magnetic components, and a signal processing circuit, wherein the plurality of magnetoresistive sensors are connected via a circuit board and are disposed on the circuit board; the signal processing circuit is not on the circuit board and is located outside the radiation area of ​​the radiation beam emitted by the radiotherapy device; The circuit board is configured to transmit the signals acquired by the plurality of magnetoresistive sensors to the signal processing circuit; characterized in that... The method includes: Acquire an initial signal related to the displacement of one leaf of the multi-leaf grating, collected by at least one of the plurality of magnetoresistive sensors; The initial signal is preprocessed by the signal processing circuit to obtain a preprocessed signal. The preprocessed signal is sampled by the signal processing circuit to obtain a sampled signal; The blade displacement is calculated based on the sampled signal by the signal processing circuit.

7. The method according to claim 6, characterized in that, The step of sampling the preprocessed signal through the signal processing circuit to obtain a sampled signal includes: The preprocessed signal is sampled using an analog-to-digital converter with an accuracy of 16 bits or more and a speed of 2 Msps or more to obtain the sampled signal.

8. The method according to claim 6, characterized in that, The step of calculating the blade displacement based on the sampled signal using the signal processing circuit includes: The blade displacement is calculated based on the sampled signal using an arctangent difference algorithm.

9. The method according to claim 8, characterized in that, The calculation of the blade displacement based on the sampled signal using the arctangent difference algorithm includes: The sampled signal is converted into a square wave signal, and the number of displacement cycles is determined based on the square wave signal; simultaneously The sampled signal is subdivided using the arctangent difference calculation algorithm to determine the relative displacement within the period of the square wave signal corresponding to the sampled signal; and The blade displacement is determined based on the relative displacement and the number of displacement cycles.

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