An ultrasonic sensor detection system for multi-leaf collimator leaves

Abstract

The invention discloses an ultrasonic sensor detection system for multi-leaf collimator blades, comprising: a processor, a controller, a driver and an ultrasonic sensor; the processor receives TPS information and generates an expected set value according to the TPS information; the difference between the expected set value and the actual value is used as the input of the controller, and the controller calculates an expected PWM value according to the difference and outputs it to the driver; the driver is used to drive the blade to move according to the PWM value; the ultrasonic sensor comprises a transmitter and a receiver, the processor cyclically sends a trigger instruction to the transmitter, the transmitter sends an ultrasonic wave to the blade according to the trigger instruction, the ultrasonic wave contacts the tail end of the blade and is reflected, the reflected wave is received by the receiver and cyclically sent to the processor, and the processor calculates the actual movement position of the blade according to the change of the time difference. The ultrasonic sensor detection system uses FPGA as a processing chip, the detection cycle is achieved at the ps level, and the detection accuracy and sensor size meet the requirements.

Description

Technical Field

[0001] The present invention relates to the field of multi-leaf collimators, and in particular to an ultrasonic sensor detection system for leaves of a multi-leaf collimator. Background Art

[0002] The multi-leaf collimator is usually in the treatment head structure, and all the leaves are arranged in the leaf box, which has a track for the movement of the leaves, and the leaves can slide in it. When the medical linear accelerator is in use, the leaf box will rotate with the treatment head rotation system. However, each leaf in the multi-leaf collimator will reciprocate independently in one dimension in its track, thus forming various radiation fields that adapt to the shape of the lesion.

[0003] It is often difficult to control installation errors using split zero point detection methods such as external mechanical limits and photoelectric switches for traditional multi-leaf collimators.

[0004] Currently, no effective solution has been proposed for the problems in the prior art. Summary of the invention

[0005] The object of the present invention is to provide an ultrasonic sensor detection system for multi-leaf collimator leaves in view of the deficiencies in the prior art.

[0006] The ultrasonic sensor detection system for multi-leaf collimator leaves includes a processor, a controller, a driver and an ultrasonic sensor;

[0007] The processor receives TPS information and generates a desired setting value according to the TPS information;

[0008] The difference between the expected set value and the actual value is used as the input of the controller, and the controller calculates a desired PWM value according to the difference and outputs it to the driver;

[0009] The driver is used to drive the blade to move according to the PWM value;

[0010] The ultrasonic sensor includes a transmitter and a receiver. The processor cyclically sends a trigger instruction to the transmitter. The transmitter sends ultrasonic waves to the blade according to the trigger instruction. The ultrasonic waves are reflected after contacting the tail end of the blade. The reflected waves are received by the receiver and cyclically sent to the processor. The processor calculates the actual movement position of the blade according to the change of time difference.

[0011] Furthermore, the TPS information includes the position information of all leaves outlined for the lesion by the treatment planning system.

[0012] Furthermore, the expected set value is the distance information of the expected blade movement in each control cycle subdivided by the processor according to the TPS.

[0013] Furthermore, the driver includes an H-bridge structure and a motor, which is used to convert PWM waveforms of different widths into voltage signals for driving the motor. The rotation of the motor drives the mechanical transmission device to drive the blades to move.

[0014] Furthermore, the processor is an FPGA, which cyclically sends trigger instructions to the transmitter according to its acquisition clock.

[0015] Furthermore, by using FPGA as a processor, the detection cycle can reach ps level.

[0016] Furthermore, the transmitter emits an ultrasonic wave, and the processor records the emission time. The ultrasonic wave hits the blade surface and refracts back and is received by the receiver. At this time, the processor records the time again. The movement distance S of the ultrasonic wave is the product of the time difference Δt and the propagation speed V of the ultrasonic wave, as shown in the formula:

[0017] S=V*Δt.

[0018] Furthermore, each movement position of the blade is calculated according to the following formula:

[0019] L=(SH) / tan(α)

[0020] Where H is the distance from the radiation area to the probe; α is the inclination angle of the slope relative to the direction of blade travel.

[0021] Furthermore, the size of the ultrasonic sensor is at the micron level, and the accuracy also reaches the micron level.

[0022] Furthermore, the controller can convert the difference between the desired set value and the actual value into an electrical signal.

[0023] Compared with the prior art, the ultrasonic sensor detection system for multi-leaf collimator blades of the present invention has the following significant advantages:

[0024] 1. The ultrasonic sensor detection system for multi-leaf collimator blades described in the present invention can realize a closed-loop sensor system for the multi-leaf collimator.

[0025] 2. The ultrasonic sensor detection system for multi-leaf collimator blades described in the present invention has an ultrasonic sensor size that has entered the micron level and an accuracy that can also reach the micron level. By using FPGA as a processing chip, the detection cycle can reach the ps level, and both the detection accuracy and sensor size meet the requirements of MLC. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a top view of the multi-leaf collimator;

[0027] Figure 2 It is a structural schematic diagram of the ultrasonic sensor detection system for multi-leaf collimator leaves according to the present invention;

[0028] Figure 3 Schematic diagram of the leaf detection principle of a multi-leaf collimator. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0033] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0034] In addition, the terms "installed", "set", "provided with", "connected", "slidingly connected", "fixed", "clipped", and "set" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] In addition, the term "plurality" shall mean two or more.

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] like Figures 1 to 3 As shown, the ultrasonic sensor detection system for multi-leaf collimator leaves includes: a processor, a controller, a driver and an ultrasonic sensor;

[0038] The processor receives TPS information and generates a desired setting value according to the TPS information;

[0039] The difference between the expected set value and the actual value is used as the input of the controller, and the controller calculates a desired PWM value according to the difference and outputs it to the driver;

[0040] The driver is used to drive the blade to move according to the PWM value;

[0041] The ultrasonic sensor includes a transmitter and a receiver. The processor cyclically sends a trigger instruction to the transmitter. The transmitter sends ultrasonic waves to the blade according to the trigger instruction. The ultrasonic waves are reflected after contacting the tail end of the blade. The reflected waves are received by the receiver and cyclically sent to the processor. The processor calculates the actual movement position of the blade according to the change of time difference.

[0042] Furthermore, the TPS information includes the position information of all leaves outlined for the lesion by the treatment planning system.

[0043] Furthermore, the expected set value is the distance information of the expected blade movement in each control cycle subdivided by the processor according to the TPS.

[0044] Furthermore, the driver includes an H-bridge structure and a motor, which is used to convert PWM waveforms of different widths into voltage signals for driving the motor. The rotation of the motor drives the mechanical transmission device to drive the blades to move.

[0045] Furthermore, the processor is an FPGA, which cyclically sends trigger instructions to the transmitter according to its acquisition clock.

[0046] Furthermore, by using FPGA as a processor, the detection cycle can reach ps level.

[0047] Furthermore, the transmitter emits an ultrasonic wave, and the processor records the emission time. The ultrasonic wave hits the blade surface and refracts back and is received by the receiver. At this time, the processor records the time again. The movement distance S of the ultrasonic wave is the product of the time difference Δt and the propagation speed V of the ultrasonic wave, as shown in the formula:

[0048] S=V*Δt.

[0049] Furthermore, each movement position of the blade is calculated according to the following formula:

[0050] L=(SH) / tan(α)

[0051] Where H is the distance from the radiation area to the probe; α is the inclination angle of the slope relative to the direction of blade travel.

[0052] Furthermore, the size of the ultrasonic sensor is at the micron level, and the accuracy also reaches the micron level.

[0053] Furthermore, the controller can convert the difference between the desired set value and the actual value into an electrical signal.

[0054] Specifically, the transmitter emits an ultrasonic wave, and the core processing chip (such as FPGA, ARM, etc.) records the time of emission. The ultrasonic wave hits the surface of the blade and refracts back, and is received by the receiver. At this time, the core processing chip records the time again. The movement distance S of the ultrasonic wave is the product of the time difference Δt and the propagation speed V of the ultrasonic wave. As shown in the formula:

[0055] S=V*Δt (1)

[0056] Since the distance from the radiation zone to the probe is a fixed value, assuming it is H, and the inclination angle of the slope relative to the direction of the blade's travel is α, each moving position of the blade can be obtained as shown in the following formula:

[0057] L=(SH) / tan(α) (2)

[0058] When L≤0, it means that the blade is at the rear end, otherwise it has moved within the effective range. This solution is not limited to the cases listed in this article. The change in the shape of the rear end can be regular, such as sawtooth, trapezoid, arc, etc., which can be converted into the movement position according to the set rules.

[0059] Each blade has its own zero point device at the rear end. Figure 3As shown in the figure, a rectangular protrusion is shown. The zero point device can be used as long as the change trend is significantly different from that of the previous part. As the blade moves toward the front end, the time difference Δt gradually increases. When it reaches the rectangular protrusion, it decreases significantly and remains for a period of time, indicating that it has reached the zero point position. The blade moves to the front end, and the electronic control system detects this sudden change and controls the drive of the blade to stop. That is, the zero point position and the position where L starts to be not greater than 0 are the two limit positions of the blade movement.

[0060] Ultrasonic sensor detection system Figure 2 As shown, the host computer system sends the set blade position, which is subtracted from the detection result of the ultrasonic sensor and the actual blade position obtained by formula (2) to obtain the position error. The core processor (such as FPGA, ARM, single-chip microcomputer, etc.) designs the controller, and obtains the corresponding control amount according to the error value and converts it into an electrical signal, thereby driving the blade to move through the driving mechanism until the actual position of the blade matches the set position.

[0061] In addition, according to the above analysis, when the blade moves to two extreme positions, the controller no longer controls the blade movement according to the actual error value, but directly takes braking measures to stop the blade movement as soon as possible. Of course, under normal circumstances, the set value should not exceed two extreme positions.

[0062] Furthermore, the current size of ultrasonic sensors has entered the micron level, and the accuracy can also reach the micron level. Using FPGA as the processing chip, the detection cycle can be achieved at the ps level, and the detection accuracy and sensor size both meet the requirements of MLC.

[0063] like Figure 1 and Figure 3 As shown, a multi-leaf collimator is generally in the treatment head structure, and all the blades are arranged in a blade box. The blade box has a track for the movement of the blades, in which the blades can slide. When the medical linear accelerator is in use, the blade box will rotate along with the treatment head rotation system. However, each blade in the multi-leaf collimator will independently perform one-dimensional reciprocating motion in its track, thereby forming various radiation fields that adapt to the shape of the lesion. This scheme discusses this movement. In this scheme, the detection signal circuit board is arranged at the openings on both sides of the leaf box, and the detection device uses an ultrasonic sensor. This type of sensor technology is mature, and the smallest size can be micron-level. Even if each blade is equipped with an ultrasonic probe, the layout of the circuit board will not be tight. The structure of each leaf is as follows Figure 3 As shown, in order to ensure that the radiation does not penetrate and thus protect the patient's normal tissue, the blades are designed with a fixed shape at the rear end, such as Figure 3 The slope shape shown in the figure may be called the detection area, and the front end part used to block the rays is called the radiation area. The projection length of the slope in the direction of blade movement needs to meet the total movement stroke of the blade.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and variations. 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 claims of the present invention.

Claims

1. An ultrasonic sensor detection system for multi-leaf collimator leaves, characterized in that: include: processors, controllers, drivers, and ultrasonic sensors; The processor receives TPS information and generates a desired setting value according to the TPS information; The difference between the expected set value and the actual value is used as the input of the controller, and the controller calculates a desired PWM value according to the difference and outputs it to the driver; The driver is used to drive the blade to move according to the PWM value; The ultrasonic sensor includes a transmitter and a receiver. The processor cyclically sends a trigger instruction to the transmitter. The transmitter sends an ultrasonic wave to the blade according to the trigger instruction. The ultrasonic wave is reflected after contacting the tail end of the blade. The reflected wave is received by the receiver and cyclically sent to the processor. The processor calculates the actual movement position of the blade according to the change of the time difference. Each movement position of the blade is calculated according to the following formula: L=(SH) / tan(α) Where H is the distance from the radiation area to the probe; α is the inclination angle of the slope relative to the direction of blade travel; The TPS information includes the position information of all leaves outlined for the lesion by the treatment planning system; The expected set value is the distance information of the expected blade movement in each control cycle subdivided by the processor according to the TPS.

2. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 1, characterized in that: The driver includes an H-bridge structure and a motor, which is used to convert PWM waveforms of different widths into voltage signals for driving the motor. The rotation of the motor drives the mechanical transmission device to drive the blades to move.

3. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 2, characterized in that: The processor is an FPGA, which cyclically sends trigger instructions to the transmitter according to its acquisition clock.

4. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 3, characterized in that: By using FPGA as the processor, the detection cycle can reach the ps level.

5. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 4, characterized in that: The transmitter emits an ultrasonic wave, and the processor records the emission time. The ultrasonic wave hits the blade surface and refracts back and is received by the receiver. At this time, the processor records the time again. The movement distance S of the ultrasonic wave is the product of the time difference Δt and the propagation speed V of the ultrasonic wave, as shown in the formula: S=V*Δt.

6. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 1, characterized in that: The size of the ultrasonic sensor is micron-level, and the accuracy also reaches micron-level.

7. The ultrasonic sensor detection system for multi-leaf collimator blades according to claim 1, characterized in that: The controller is capable of converting the difference between the desired set value and the actual value into an electrical signal.

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