Multi-leaf grating displacement detection method, circuit and device, multi-leaf grating and equipment

Abstract

The invention relates to a multi-leaf grating displacement detection method, circuit and device, a multi-leaf grating and equipment. The method comprises the following steps: acquiring a contact voltage and a full-scale voltage of the thin film potentiometer in at least one sampling batch, acquiring a creep state of the thin film potentiometer, compensating the contact voltage based on the creep state to obtain a compensated contact voltage, and calculating the full-scale voltage of the thin film potentiometer according to the compensated contact voltage. And displacement information of the blades in the multi-leaf grating is determined according to the compensated contact voltage and the full-scale voltage. According to the method, the displacement information of the blades in the multi-leaf grating is measured by adopting the thin film potentiometer, the thin film potentiometer has good magnetic compatibility and relatively high radiation resistance and is suitable for application environments with high magnetic fields and high radiation, the universality of grating displacement detection is improved, creep interference is reduced at the same time, and the accuracy of grating displacement detection is improved. And the accuracy of the finally obtained displacement information is improved.

Description

Technical Field

[0001] The present application relates to the field of radiotherapy technology, and in particular to a multi-leaf grating displacement detection method, circuit, device, multi-leaf grating and equipment. Background Art

[0002] The multileaf grating is a component of the radiotherapy system and can be moved under the control of the radiotherapy system to form a beam shape that meets the needs.

[0003] The precise control of displacement depends on the precise detection of displacement. In the related art, a magnetic encoder is usually used to detect the displacement of the leaves in the multi-leaf grating.

[0004] However, the magnetic encoder is easily disturbed by the magnetic field and cannot be used, so the grating displacement detection method in the related art is not suitable for the radiotherapy system including the magnetic resonance system and has poor versatility. Summary of the invention

[0005] Based on this, it is necessary to provide a multi-leaf grating displacement detection method, circuit, device, multi-leaf grating and equipment to address the above technical problems.

[0006] In a first aspect, the present application provides a multi-leaf grating displacement detection method, comprising:

[0007] obtaining a contact voltage and a full-scale voltage of a thin-film potentiometer in at least one sampling batch;

[0008] Acquiring a creep state of the thin film potentiometer, and based on the creep state, compensating the contact voltage to obtain a compensated contact voltage;

[0009] The displacement information of the blade is determined based on the compensated contact voltage and the full-scale voltage.

[0010] In one embodiment, obtaining a creep state of a thin film potentiometer includes:

[0011] Obtaining the resistance change of the thin film potentiometer between adjacent sampling batches;

[0012] The creep state of the thin film potentiometer is determined based on the comparison result of the resistance change amount and the preset change amount threshold.

[0013] In one embodiment, based on obtaining the compensated contact voltage, the method includes:

[0014] Obtain the film resistance corresponding to the contact voltage;

[0015] The compensated contact voltage is determined based on the relationship between the film resistance and the creep characteristic of the film potentiometer; the creep characteristic relationship is used to characterize the corresponding relationship between the resistance change caused by creep and the creep duration.

[0016] In one embodiment, determining the compensated contact voltage according to the relationship between the film resistance and the creep characteristic of the film potentiometer includes:

[0017] Determine the resistance change corresponding to the creep time of the contact voltage based on the creep characteristic relationship;

[0018] Obtain the resistance difference between the film resistance and the resistance change;

[0019] The compensated contact voltage is determined based on the resistance difference and the input current of the film potentiometer.

[0020] In a second aspect, the present application provides a grating displacement detection circuit, comprising:

[0021] A constant current source circuit, a thin film potentiometer, an analog switch circuit, a sampling circuit and a control circuit; the sliding contact in the thin film potentiometer is arranged on the blades of the multi-leaf grating, and the blades can drive the sliding contact to move on the thin film resistor of the thin film potentiometer;

[0022] The constant current source circuit is used to generate input current, and the analog switch circuit is used to be turned on under the control of the control circuit, so that the sampling circuit samples the contact voltage and full-scale voltage of the film potentiometer;

[0023] The control circuit is used to obtain the creep state of the film potentiometer, and based on the creep state, compensate the contact voltage to obtain the compensated contact voltage, and determine the displacement information of the blade according to the compensated contact voltage and the full-scale voltage.

[0024] In one of the embodiments, the grating displacement detection circuit further includes a voltage follower filter circuit, which is connected between the analog switch circuit and the sampling circuit for signal filtering.

[0025] In one embodiment, the voltage follower filter circuit includes an operational amplifier, a first capacitor, a second capacitor, a first resistor and a second resistor; the first capacitor and the second resistor are connected in parallel, one end of the first capacitor and the second resistor are respectively connected to the input end of the operational amplifier, and the other end of the first capacitor and the second resistor are respectively connected to the output end of the operational amplifier; the first resistor is connected to the output end of the operational amplifier; one end of the second capacitor is connected to the output end of the operational amplifier, and the other end is grounded.

[0026] In a third aspect, the present application further provides a grating displacement detection device, which uses a thin film potentiometer to measure the displacement information of leaves in a multi-leaf grating, including:

[0027] A data acquisition module, used for acquiring a contact voltage and a full-scale voltage of a thin film potentiometer in at least one sampling batch;

[0028] A creep monitoring module is used to obtain a creep state of a thin film potentiometer, and based on the creep state of the thin film potentiometer, compensate the contact voltage to obtain a compensated contact voltage;

[0029] The displacement determination module is used to determine the displacement information of the blades in the grating according to the compensated contact voltage and the full-scale voltage.

[0030] In a fourth aspect, the present application further provides a multi-leaf grating, which includes a plurality of blades and any one of the aforementioned grating displacement detection circuits, and the blades and the grating displacement detection circuit are arranged correspondingly.

[0031] In a fifth aspect, the present application also provides a medical device, which includes the above-mentioned multi-leaf grating.

[0032] In the above-mentioned multi-leaf grating displacement detection method, circuit, device, multi-leaf grating and equipment, the creep state of the thin film potentiometer is obtained by obtaining the contact voltage and full-scale voltage of the thin film potentiometer under at least one sampling batch, and based on the creep state, the contact voltage is compensated to obtain the compensated contact voltage, so as to determine the displacement information of the blades in the multi-leaf grating according to the compensated contact voltage and full-scale voltage. In the above-mentioned method, a thin film potentiometer is used to measure the displacement information of the blades in the multi-leaf grating. The thin film potentiometer has good magnetic compatibility and strong radiation resistance, is suitable for high magnetic field and high radiation application environment, and improves the versatility of grating displacement detection. In addition, for monitoring the creep state of the thin film potentiometer, the contact voltage can be compensated based on the creep state, so as to use the compensated contact voltage to determine the displacement information, thereby reducing creep interference and improving the accuracy of the displacement information finally obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0034] FIG1 is a block diagram of a grating displacement detection circuit in one embodiment;

[0035] FIG2 is a schematic diagram of the structure of a constant current source circuit in one embodiment;

[0036] FIG3 is a schematic diagram of the structure of a voltage follower filter circuit in one embodiment;

[0037] FIG4 is a block diagram of a grating displacement detection circuit in another embodiment;

[0038] FIG5 is a schematic diagram of a flow chart of a grating displacement detection method in one embodiment;

[0039] FIG6 is a schematic diagram of a process for determining a first displacement and a second displacement in one embodiment;

[0040] FIG7 is a schematic diagram of a process for determining a second displacement in one embodiment;

[0041] FIG8 is a schematic diagram of a process for determining a creep state in one embodiment;

[0042] FIG9 is a schematic diagram of a process for determining a compensated contact voltage in one embodiment;

[0043] FIG10 is a schematic diagram of a flow chart of determining the compensated contact voltage in another embodiment;

[0044] FIG11 is a schematic flow chart of a grating displacement detection method in another embodiment;

[0045] FIG. 12 is a structural block diagram of a grating displacement detection device in one embodiment.

[0046] Description of Figure Numbers:

[0047] 101——Constant current source circuit;

[0048] 102 – Thin film potentiometer;

[0049] 103——Analog switch circuit;

[0050] 104——sampling circuit;

[0051] 105——control circuit;

[0052] 106——Voltage follower filter circuit. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0054] The multileaf grating displacement detection method provided in the embodiment of the present application can be applied to the grating displacement detection circuit shown in Figure 1. Before describing the process of the multileaf grating displacement detection method in detail, the multileaf grating displacement detection circuit provided in the embodiment of the present application is described first.

[0055] In an exemplary embodiment, as shown in FIG1 , a multi-leaf grating displacement detection circuit is provided, comprising:

[0056] The constant current source circuit 101, the thin film potentiometer 102, the analog switch circuit 103, the sampling circuit 104 and the control circuit 105. The sliding contact in the thin film potentiometer 102 is arranged on the multi-leaf blade, and the blade can drive the sliding contact to move on the thin film resistor of the thin film potentiometer 102.

[0057] The constant current source circuit 101 is used to generate input current, and the analog switch circuit 103 is used to be turned on under the control of the control circuit 105 so that the sampling circuit 104 samples the contact voltage and full-scale voltage of the thin film potentiometer 102 .

[0058] The control circuit 105 is used to obtain the resistance creep state of the thin film potentiometer 102, and based on the resistance creep state, compensate the contact voltage to obtain the compensated contact voltage, and determine the displacement information of the leaves in the multi-leaf grating according to the compensated contact voltage and the full-scale voltage.

[0059] The multi-leaf grating includes multiple leaves and is an optical device in the radiotherapy system. The beam shape generated by the radiotherapy system can be changed by moving the leaves. The sliding contact in the thin film potentiometer 102 in the above-mentioned grating displacement detection circuit is set on the leaf. The leaf can drive the sliding contact to move on the thin film resistor of the thin film potentiometer 102 when moving. The multi-leaf grating can be connected to the grating displacement detection circuit through the thin film potentiometer 102 to realize the detection of the displacement of the leaves in the multi-leaf grating.

[0060] Exemplarily, as shown in FIG2 , the constant current source circuit 101 in the multi-leaf grating displacement detection circuit is connected to the thin film potentiometer 102, the thin film potentiometer 102 is connected to the analog switch circuit 103, the analog switch circuit 103 is connected to the sampling circuit 104, and the sampling circuit 104 is connected to the controller 105. The connection relationship between the various parts in the grating displacement detection circuit may not be limited to the connection relationship in FIG1 .

[0061] The thin film potentiometer 102 includes a thin film resistor and a sliding contact. The position on the thin film resistor that contacts the sliding contact is called a contact point, and the voltage generated at the contact point of the sliding contact is the contact voltage. When the blade moves, the blade will drive the sliding contact to move on the thin film resistor, causing the film resistance to change, and under the action of the constant current source circuit 101, the contact voltage changes with the change of the film resistance. During the movement of the blade, the sampling circuit 104 cooperates with the analog switch circuit 103 to perform multiple batches of sampling on the thin film potentiometer 102 to obtain the contact voltage and full-scale voltage of the thin film potentiometer 102 in each sampling batch. The controller 105 can determine the displacement information of the blade based on the contact voltage and full-scale voltage in each sampling batch.

[0062] Next, each part of the multi-leaf grating displacement detection circuit is introduced in detail:

[0063] The constant current source circuit 101 is used to provide a constant current, which can be used as the input current of the entire multi-leaf grating displacement detection circuit. Optionally, the constant current source circuit 101 can be a high-precision constant current source circuit built based on a differential amplifier.

[0064] Exemplarily, as shown in FIG2 , the constant current source circuit 101 includes a differential amplifier D and an operational amplifier O. The negative terminal of the differential amplifier D is grounded, and the positive terminal is connected to a reference voltage source to provide a reference voltage V REF (such as 1.25V), the SENSE terminal and the OUT terminal are short-circuited, and then connected in series with the matching resistor Rm and the thin film potentiometer 102 to the ground. The voltage between the matching resistor Rm and the thin film potentiometer 102 returns to the REF port of the differential amplifier D through the entire circuit. In this way, a constant current control closed loop is formed. When the film resistance value increases, the voltage between the matching resistor Rm and the thin film potentiometer 102 increases, the voltage at the REF port increases, the voltage at the OUT port increases, and the voltage across the matching resistor Rm remains unchanged, that is, the current flowing through the matching resistor Rm and the thin film potentiometer 102 remains unchanged, and vice versa.

[0065] The input current Io provided by the constant current source circuit 101 is only equal to the reference voltage V REF It is related to the matching resistance Rm, and the calculation formula is: .

[0066] The thin film potentiometer 102 is a variable resistance device, which can change the film resistance when the blade drives the sliding contact to move on the thin film resistor, that is, corresponding to different contact voltages. The range of the thin film resistor can be customized based on the grating size and the movement stroke.

[0067] The analog switch circuit 103 may include a plurality of analog switches, and the analog switches may be switched based on a control signal output by the controller 105 to achieve conduction and disconnection of different transmission paths.

[0068] Exemplarily, the analog switch circuit 103 includes an analog switch with high integration and 4 single-pole double-throw switches. The two voltage signals (contact voltage and full-scale voltage) generated by the thin film potentiometer 102 are connected to the double-throw port of the analog switch. When the analog switch conducts the port connected to the current input terminal of the thin film potentiometer 102, the sampling circuit 104 can sample and obtain the full-scale voltage of the thin film potentiometer 102; when the analog switch conducts the port connected to the contact of the thin film potentiometer 102, the sampling circuit 104 can sample and obtain the contact voltage of the thin film potentiometer 102.

[0069] The sampling circuit 104 may include an analog-to-digital converter (ADC). The sampling rate of the sampling circuit 104 needs to be adapted to the movement speed of the blade. When the movement speed of the blade is fast, a sampling circuit 104 with a higher sampling rate needs to be configured; when the movement speed of the blade is slow, a sampling circuit 104 with a lower sampling rate can be configured.

[0070] The controller 105 may include a Field-Programmable Gate Array (FPGA) chip configured with corresponding signal control and logic algorithms to achieve detection of grating displacement information.

[0071] In the embodiment of the present application, the multi-leaf grating displacement detection circuit provided includes a constant current source circuit, a thin film potentiometer, an analog switch circuit, a sampling circuit and a control circuit; the constant current source circuit is used to generate an input current, the analog switch circuit is used to conduct under the control of the control circuit, so that the sampling circuit samples the contact voltage and full-scale voltage of the thin film potentiometer; the control circuit is used to obtain the resistance creep state of the thin film potentiometer, and based on the resistance creep state, the contact voltage is compensated to obtain the compensated contact voltage, and the displacement information of the blade is determined by the compensated contact voltage and the full-scale voltage. In the above-mentioned grating displacement detection circuit, the sliding contact in the thin film potentiometer is arranged on the blade of the multi-leaf grating, and the blade can drive the sliding contact to move on the thin film resistor of the thin film potentiometer to change the contact voltage of the thin film potentiometer, and the controller can determine the displacement information of the blade based on the influence of the blade movement on the contact voltage. The thin film potentiometer has good magnetic compatibility and strong radiation resistance, and is suitable for high magnetic field and high radiation application environments, which improves the versatility of grating displacement detection.

[0072] To enhance the driving capability of the voltage signal, in one embodiment, as shown in FIG. 1 , the multi-leaf grating displacement detection circuit may further include a voltage follower filter circuit 106 for signal filtering.

[0073] The voltage follower filter circuit 106 is used to pass low frequencies and block high frequencies. In addition, the voltage follower filter circuit 106 can realize low-pass filtering and filter out some high-frequency interference, and at the same time, increase the driving capability of the previous stage signal and reduce the output impedance without changing the voltage.

[0074] Exemplarily, the voltage follower filter circuit 106 may be connected between the analog switch circuit 103 and the sampling circuit 104 .

[0075] In an optional embodiment, as shown in FIG3 , the voltage follower filter circuit 106 includes an operational amplifier O, a first capacitor C1, a second capacitor C2, a first resistor R1, and a second resistor R2. The first capacitor C1 and the second resistor R2 are connected in parallel, one end of the first capacitor C1 and the second resistor R2 are respectively connected to the input end of the operational amplifier O, and the other ends of the first capacitor C1 and the second resistor R2 are respectively connected to the output end of the operational amplifier O; the first resistor R1 is connected to the output end of the operational amplifier O; one end of the second capacitor C2 is connected to the output end of the operational amplifier O, and the other end is grounded.

[0076] The first capacitor C1 and the second resistor R2 form a feedback loop, which determines the time constant of the feedback; the second capacitor C2 and the first resistor R1 form an RC filter, which determines the time constant of the load.

[0077] Exemplarily, the product of the first capacitor C1 and the second resistor R2 is set to be greater than the product of the first resistor R1 and the second capacitor C2, that is, , which can make the voltage follower filter circuit 106 remain stable.

[0078] When the grating displacement detection circuit is applied to a multi-leaf grating, the grating displacement detection circuit with a common controller 105 as shown in Fig. 4 can be used. The sampling and detection control of each leaf by the controller 105 are independent and can be controlled synchronously.

[0079] In the case of a radiotherapy system with a large number of single-side blades of a multi-leaf grating (e.g., 102 blades), the thickness of the blades will be very thin, which means that the width of the thin film resistor in the thin film potentiometer 102 that contacts the blades through the sliding contact is very narrow. At the same time, for radiotherapy systems including magnetic resonance, the design of materials takes into account magnetic compatibility, and the movement stroke of the blades needs to cover a large stroke (e.g., ≥135mm), which means that the length of the thin film resistor is very long. A long and thin thin film resistor will make its resistance value relatively large, up to about 100KΩ.

[0080] In order to achieve a higher detection accuracy (such as 0.01mm) and meet the full scale of the thin film potentiometer 102 of about 100KΩ, the sampling circuit 104 for 102 leaves is placed on a board, which will limit the space, so a 6-8 channel integrated ADC is required. In practical applications, the leaves move quickly, so the sampling rate of the ADC is required to be above 200kSPS. Therefore, in the application scenario of displacement detection of multi-leaf gratings in magnetic resonance systems, the above sampling circuit 104 can use a 500Ksps 16-bit 8-channel synchronous sampling ADC.

[0081] Based on the above multi-leaf grating displacement detection circuit, the present application also provides a multi-leaf grating displacement detection method, which uses a thin film potentiometer to measure the displacement information of the leaves in the multi-leaf grating. Taking the method applied to the controller in FIG. 1 as an example, as shown in FIG. 5, the method includes:

[0082] S510: Acquire the contact voltage and full-scale voltage of the thin film potentiometer in at least one sampling batch.

[0083] The thin film potentiometer includes a sliding contact and a thin film resistor in contact with the sliding contact. The sliding contact is fixedly arranged on the side of the blade in the multi-leaf grating. When the blade moves, the sliding contact can be driven to move on the thin film resistor to change the film resistance and contact voltage of the thin film potentiometer. The contact voltage is the voltage generated at the contact point between the sliding contact and the thin film resistor. The full-scale voltage is the power supply voltage provided by the constant current source circuit for the entire grating displacement detection circuit.

[0084] Optionally, the sampling circuit can perform multiple batches of sampling on the thin film potentiometer, and cooperate with the analog switch circuit to switch the transmission path, so as to obtain the contact voltage and full-scale voltage of the thin film potentiometer in each sampling batch. The controller obtains the contact voltage and full-scale voltage of the thin film potentiometer sampled by the sampling circuit in at least one sampling batch.

[0085] S520, obtaining a creep state of the thin film potentiometer, and compensating the contact voltage according to the creep state to obtain a compensated contact voltage.

[0086] In practical applications, the contact voltage will be disturbed by the creep of the film potentiometer. In order to reduce the creep interference, it is necessary to obtain the creep state of the film potentiometer to determine whether the film potentiometer has creeped, and compensate the contact voltage according to the creep state to obtain the compensated contact voltage. The purpose of compensating the contact voltage is to reduce the influence of creep on the contact voltage.

[0087] Optionally, the controller may obtain multiple contact voltages of the thin film potentiometer under continuous sampling batches, splice the multiple contact voltages in time sequence to form a contact voltage sequence, and input the contact voltage sequence into a pre-trained creep detection model to obtain the creep state output by the creep detection model. Exemplarily, the creep detection model may be a neural network model, such as a deep learning model. The controller may also determine the film resistance of the thin film potentiometer under the corresponding contact voltage to determine the creep state according to the film resistance under adjacent sampling batches.

[0088] Optionally, after obtaining the creep state of the thin film potentiometer, the controller may adopt different compensation strategies based on different creep states to compensate the contact voltage to obtain the compensated contact voltage. Exemplarily, when the creep state of the thin film potentiometer is no creep, the corresponding compensation strategy is to directly use the collected contact voltage as the compensated contact voltage; when the creep state of the thin film potentiometer is creep, the corresponding compensation strategy is to increase the collected contact voltage by a preset compensation value to obtain the compensated contact voltage. The preset compensation value can be a positive value or a negative value, and can be predetermined based on the actual application environment of the thin film potentiometer.

[0089] S530: Determine the displacement information of the blade according to the compensated contact voltage and the full-scale voltage.

[0090] The displacement information of the blade is used to characterize the displacement of the blade relative to different reference objects. Exemplarily, the displacement information of the blade may include the absolute displacement of the blade relative to the thin film resistor in the thin film potentiometer, and / or the relative displacement of the blade between different sampling batches.

[0091] Optionally, for each sampling batch, the controller can obtain the voltage ratio between the contact voltage after compensation and the full-scale voltage, and determine the displacement corresponding to the voltage ratio according to a preset ratio-displacement relationship as the absolute displacement of the blade in the sampling batch. The absolute displacement of the thin film potentiometer in at least two sampling batches can also be obtained, and the absolute displacement of the sampling sequence later minus the absolute displacement of the sampling sequence earlier is used to obtain the relative displacement of the blade.

[0092] Optionally, after obtaining the displacement information of the blade, the controller can also determine the moving speed of the light blade based on the displacement information. For example, in the case of unidirectional linear movement of the blade, the controller can record the moving time T of the blade in each sampling batch, and determine the moving speed V1=P / T of the blade according to the absolute displacement P of the blade in each sampling batch, or record the interval time △T between adjacent sampling batches, and determine the moving speed V2=△P / △T of the blade according to the relative displacement △P of the blade between adjacent sampling batches.

[0093] In an embodiment of the present application, the creep state of the thin film potentiometer is obtained by obtaining the contact voltage and full-scale voltage of the thin film potentiometer under at least one sampling batch, and based on the creep state, the contact voltage is compensated to obtain the compensated contact voltage, so as to determine the displacement information of the blades in the multi-leaf grating according to the compensated contact voltage and the full-scale voltage. In the above method, a thin film potentiometer is used to measure the displacement information of the blades in the multi-leaf grating. The thin film potentiometer has good magnetic compatibility and strong radiation resistance, is suitable for high magnetic field and high radiation application environments, and improves the versatility of grating displacement detection. In addition, for monitoring the creep state of the thin film potentiometer, the contact voltage can be compensated based on the creep state, so as to use the compensated contact voltage to determine the displacement information, thereby reducing creep interference and improving the accuracy of the displacement information finally obtained.

[0094] The absolute displacement of the blade relative to the thin film resistor in the thin film potentiometer can be recorded as the first displacement, and the relative displacement of the blade between adjacent sampling batches can be recorded as the second displacement. When the displacement information of the blade includes the first displacement and the second displacement, in one embodiment, as shown in FIG6 , the above S530, determining the displacement information of the blade according to the compensated contact voltage and the full-scale voltage, includes:

[0095] S610, obtaining a displacement relational expression; the displacement relational expression is used to characterize that the ratio of the first displacement to the contact voltage is equal to the ratio of the length of the thin film resistor to the contact voltage to the full-scale voltage.

[0096] Among them, when the blade drives the sliding contact to move unidirectionally linearly on the thin film resistor, the contact voltage is proportional to the displacement of the sliding contact on the thin film resistor, and correspondingly proportional to the first displacement of the blade relative to the thin film resistor, and the ratio of the first displacement to the contact voltage at any moment is equal to the ratio of the length of the thin film resistor to the full-scale voltage.

[0097] Optionally, the controller obtains a pre-built and stored displacement relationship, which is used to characterize the correlation between the first displacement, the length of the thin film resistor, the contact voltage, and the full-scale voltage under the corresponding sampling batch. The above displacement relationship is specifically used to characterize the first displacement The ratio of the length L of the film resistor is equal to the contact voltage With full-scale voltage Ratio:

[0098]

[0099] Where T represents the sampling batch, represents the first displacement under sampling batch T, represents the contact voltage under the sampling batch T, L represents the length of the thin film resistor, Indicates the full-scale voltage of the film potentiometer.

[0100] S620: For each sampling batch, determine the first displacement of the blade according to the length of the thin film resistor, the contact voltage, the full-scale voltage, and the displacement relationship.

[0101] Optionally, after obtaining the above displacement relationship, for each sampling batch, the controller may input the length of the thin film resistor and the contact voltage and full-scale voltage under the sampling batch into the displacement relationship to determine the first displacement of the blade under each sampling batch. The controller may calculate the first displacement based on the above displacement relationship :

[0102]

[0103] S630: Obtain the difference between the first displacements of the blade in adjacent sampling batches as the second displacement of the blade.

[0104] Optionally, the controller may obtain two first displacements of the blade under adjacent sampling batches based on the aforementioned method of determining the first displacement, and use the first displacement with a later sampling sequence minus the first displacement with a previous sampling sequence to obtain the relative displacement of the blade between the two sampling batches, that is, the second displacement of the blade. Exemplarily, T1 and T2 are adjacent sampling batches (T2 is later than T1), the first displacement of the blade relative to the thin film resistor under sampling batch T1 is P1, and the first displacement of the blade relative to the thin film resistor under sampling batch T2 is P2. The controller may obtain the relative displacement of the blade between adjacent sampling batches T1 and T2 based on P1 and P2, that is, the second displacement of the blade △P=P2-P1.

[0105] In the embodiment of the present application, when the displacement information includes the first displacement of the blade relative to the thin film resistor and the second displacement of the blade between adjacent sampling batches, the displacement relationship formula that characterizes that the ratio of the first displacement to the contact voltage is equal to the ratio of the length of the thin film resistor to the contact voltage to the full-scale voltage is obtained, so as to determine the first displacement of the blade for each sampling batch according to the length of the thin film resistor, the contact voltage, the full-scale voltage and the displacement relationship formula, and obtain the difference between the first displacements of the blade under adjacent sampling batches as the second displacement of the blade. In the above method, the above displacement relationship formula is used to determine the first displacement of the blade relative to the thin film resistor under any sampling batch. The determination process is convenient and fast, and can accurately reflect the absolute displacement of the blade, thereby improving the reliability and convenience of the obtained first displacement. Based on the first displacement of the blade under each sampling batch, the second displacement of the blade between adjacent sampling batches can be further determined, which is not only convenient and fast, but also correspondingly improves the diversity of the obtained displacement information.

[0106] In addition to the aforementioned method of determining the second displacement based on the first displacement, in one embodiment, as shown in FIG. 7 , the above S530, determining the displacement information of the blade according to the compensated contact voltage and the full-scale voltage, includes:

[0107] S710, obtaining a displacement change relationship; the displacement change relationship is used to characterize that the ratio of the second displacement to the length of the thin film resistor is equal to the ratio of the contact voltage change between adjacent sampling batches to the full-scale voltage.

[0108] The second displacement of the blade is the displacement change of the blade between adjacent sampling batches. When the blade drives the contact to move linearly on the thin film resistor in one direction, the second displacement of the blade is proportional to the change in the contact voltage of the thin film resistor, and the ratio of the second displacement under adjacent sampling batches to the length of the thin film resistor is equal to the ratio of the change in the contact voltage to the full-scale voltage.

[0109] Optionally, the controller obtains a pre-built and stored displacement change relationship, which is used to characterize the correlation between the second displacement, the length of the thin film resistor, the contact voltage change, and the full-scale voltage under adjacent sampling batches. The above displacement change relationship is specifically used to characterize that the ratio of the second displacement △P to the length L of the thin film resistor is equal to the contact voltage change △U to the full-scale voltage Ratio:

[0110]

[0111] Among them, T1 and T2 represent adjacent sampling batches (T2 is later than T1), represents the contact voltage under sampling batch T1, represents the contact voltage under sampling batch T2, and △U represents the change in contact voltage of the thin film potentiometer between adjacent sampling batches T1 and T2.

[0112] S720, determining a second displacement of the blade according to a relationship between the length of the thin film resistor, the change in contact voltage, the full-scale voltage, and the change in displacement.

[0113] Optionally, after obtaining the above displacement change relationship, the controller may input the length of the thin film resistor, the contact voltage change and the full-scale voltage into the displacement change relationship to determine the second displacement of the blade between adjacent sampling batches. The controller may calculate the second displacement △P based on the above displacement change relationship:

[0114]

[0115] In the embodiment of the present application, when the displacement information includes the second displacement of the blade between adjacent sampling batches, a displacement change relationship is constructed in which the ratio of the second displacement to the length of the thin film resistor is equal to the ratio of the contact voltage change to the full-scale voltage between adjacent sampling batches, so as to determine the second displacement of the blade according to the length of the thin film resistor, the contact voltage change, the full-scale voltage and the displacement change relationship. In the above method, the above displacement transformation relationship directly determines the second displacement of the blade between adjacent sampling batches, the determination process is convenient and fast, and can accurately reflect the relative displacement of the blade, thereby improving the reliability and convenience of the obtained second displacement.

[0116] To improve the accuracy of the obtained creep state, in one embodiment, as shown in FIG8 , obtaining the creep state of the thin film potentiometer in S520 includes:

[0117] S810, obtaining the resistance change of the thin film potentiometer between adjacent sampling batches.

[0118] Optionally, the controller can obtain the contact voltage of the thin film potentiometer in adjacent sampling batches, and determine the film resistance corresponding to the contact voltage in each sampling batch based on the input current provided by the constant current source circuit, so as to calculate the difference in film resistance between adjacent sampling batches as the resistance change of the thin film potentiometer in adjacent sampling batches.

[0119] Exemplarily, the constant current source circuit provides an input current I, T1 and T2 represent adjacent sampling batches (T2 is later than T1), represents the contact voltage of the thin film potentiometer under sampling batch T1, Indicates the contact voltage of the thin film potentiometer under sampling batch T2. The controller can calculate the resistance value of the thin film potentiometer under sampling batch T1. , the resistance value under sampling batch T2 , and the resistance change of the thin film potentiometer in adjacent sampling batches △R=R2-R1.

[0120] S820: Determine the creep state of the thin film potentiometer according to the comparison result between the resistance change and the preset change threshold.

[0121] It should be noted that the resistance change caused by creep of the thin film potentiometer is usually small, while the resistance change caused by the blade driving the sliding contact to move on the thin film resistor is usually large. Therefore, the controller can determine the resistance creep state of the thin film potentiometer, that is, whether creep occurs, based on the value of the resistance change.

[0122] Optionally, the controller may compare the obtained resistance change with a preset change threshold value, and when the resistance change is less than the change threshold value, determine that the resistance creep state of the thin film potentiometer is creep; conversely, when the resistance change is less than or equal to the change threshold value, determine that the resistance creep state of the thin film potentiometer is no creep.

[0123] In the embodiment of the present application, the creep state of the thin film potentiometer is determined by obtaining the resistance change of the thin film potentiometer between adjacent sampling batches and comparing the resistance change with the preset change threshold. In the above method, the creep state of the thin film potentiometer is determined based on the relationship between the resistance change and the preset change threshold, which can improve the accuracy of the obtained creep state.

[0124] To improve the accuracy of compensation, in one embodiment, as shown in FIG. 9 , obtaining the compensated contact voltage in S520 includes:

[0125] S910, obtaining a film resistance value corresponding to the contact voltage.

[0126] Optionally, the controller may obtain the contact voltage of the thin film potentiometer, and determine the film resistance of the thin film potentiometer at the corresponding contact voltage according to the input current provided by the constant current source circuit. Exemplarily, the constant current source circuit provides an input current I, U represents the collected contact voltage of the thin film potentiometer, and the controller may calculate the film resistance of the thin film potentiometer corresponding to the contact voltage U. .

[0127] S920, determining the compensated contact voltage according to the relationship between the film resistance and the creep characteristic of the film potentiometer; the creep characteristic relationship is used to characterize the corresponding relationship between the resistance change caused by creep and the creep duration.

[0128] The creep characteristic relationship is the correspondence between the creep resistance change and the creep duration of the pre-calibrated thin film potentiometer. Exemplarily, the creep characteristic relationship can be represented by a curve showing the creep resistance change versus the creep duration.

[0129] Optionally, after obtaining the film resistance corresponding to the contact voltage, the controller may compensate for the influence of creep interference on the film resistance based on the creep characteristic relationship of the film potentiometer to determine the compensated contact voltage according to the compensated film resistance.

[0130] In one embodiment, as shown in FIG. 10 , the above S920, determining the compensated contact voltage according to the relationship between the film resistance and the creep characteristic of the film potentiometer, includes:

[0131] S1010, determining a resistance change corresponding to a creep time length of a contact voltage based on a creep characteristic relationship.

[0132] Among them, the thin film potentiometer has no creep, indicating that the collected contact voltage is not disturbed by creep and no substantial compensation is required. The thin film potentiometer has creep, indicating that the collected contact voltage is disturbed by creep and substantial compensation is required.

[0133] Optionally, when the controller determines that the thin film potentiometer has creeped, the controller starts timing to determine the creep duration from the start of timing to the collection of the contact voltage, and determines the resistance change corresponding to the creep duration in the creep characteristic relationship. Exemplarily, the timing is started after the thin film potentiometer is determined to have creeped, and the duration △t between the start of timing and a certain contact voltage U collected subsequently is obtained, and the resistance change corresponding to △t is determined to be △R according to the creep characteristic relationship.

[0134] S1020, obtaining a resistance difference between the film resistance and the resistance change.

[0135] The resistance difference is the compensated film resistance of the film potentiometer after the creep interference is offset / reduced.

[0136] It should be noted that when a thin film potentiometer creeps, its resistance usually increases. To offset / reduce creep interference, the resistance caused by the creep should be subtracted.

[0137] Optionally, after obtaining the resistance change corresponding to the creep time of the contact voltage, the controller uses the film resistance of the thin film potentiometer minus the resistance change to obtain the resistance difference between the film resistance and the resistance change. Exemplarily, continuing the above example, the film resistance R corresponding to the contact voltage U of the thin film potentiometer and the corresponding resistance change △R are obtained, and the resistance after offsetting / reducing the creep interference, that is, the above difference, is R-△R. Among them, when the thin film potentiometer does not creep, the corresponding creep time is 0, and △R is also 0.

[0138] S1030, determining a new voltage according to the resistance difference and the input current of the thin film potentiometer.

[0139] The input current of the film potentiometer is the constant current provided by the constant current source circuit.

[0140] Optionally, after the controller obtains the resistance value of the thin film potentiometer after offsetting / reducing creep interference, i.e., the above resistance difference, it can determine the compensated contact voltage according to the relationship among current, voltage and resistance. For example, continuing the above example, the constant current source circuit provides input current I, resistance difference R-△R, and the contact voltage after compensation for the contact voltage U is .

[0141] In the embodiment of the present application, the resistance change corresponding to the creep time of the contact voltage is determined based on the creep characteristic relationship to obtain the resistance difference between the film resistance and the resistance change, and the compensated contact voltage is determined based on the resistance difference and the input current of the film potentiometer. In the above method, the resistance change of the contact voltage corresponding to the creep time is directly determined based on the pre-calibrated creep characteristic relationship, which is not only quick and convenient, but also the creep characteristic relationship is used to characterize the corresponding relationship between the resistance change caused by creep and the creep time, which can accurately reflect the resistance change of the film potentiometer caused by creep, and can correspondingly improve the compensation reliability, thereby improving the accuracy of the compensated contact voltage.

[0142] To facilitate understanding by those skilled in the art, the multi-leaf grating displacement detection method provided by the present application is described in detail below. As shown in FIG11 , the method may include:

[0143] S1101, obtaining the resistance change of the thin film potentiometer under adjacent sampling batches; the sliding contact in the thin film potentiometer is arranged on the blades of the multi-leaf grating, and the blades can drive the sliding contact to move on the thin film resistor of the thin film potentiometer;

[0144] S1102, determining whether creep occurs in the thin film potentiometer according to the resistance change;

[0145] S1103, when the thin film potentiometer does not creep, using the collected contact voltage of the thin film potentiometer as the compensated contact voltage;

[0146] S1104, when creep occurs in the thin film potentiometer, determining a resistance change corresponding to the creep duration of the contact voltage based on a creep characteristic relationship of the thin film potentiometer; the creep characteristic relationship is used to characterize a corresponding relationship between a resistance change caused by creep and a creep duration;

[0147] S1105, obtaining the resistance difference between the film resistance and the resistance change of the film potentiometer;

[0148] S1106, determining the compensated contact voltage according to the resistance difference and the input current of the film potentiometer;

[0149] S1107, obtaining a displacement relationship formula representing that the ratio of the first displacement to the contact voltage is equal to the ratio of the length of the thin film resistor to the contact voltage to the full-scale voltage;

[0150] S1108, for each sampling batch, determining a first displacement of the blade relative to the thin film resistor according to the length of the thin film resistor, the contact voltage, the full-scale voltage, and the displacement relationship;

[0151] S1109, obtaining the difference between the first displacements of the blade in adjacent sampling batches as the second displacement of the blade between adjacent sampling batches.

[0152] It should be noted that for the description in the above S1101-S1109, reference may be made to the relevant description in the above embodiment, and the effects are similar, which will not be repeated in this embodiment.

[0153] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0154] Based on the same inventive concept, the embodiment of the present application also provides a multi-leaf grating displacement detection device for implementing the multi-leaf grating displacement detection method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more multi-leaf grating displacement detection device embodiments provided below can refer to the limitations of the multi-leaf grating displacement detection method above, and will not be repeated here.

[0155] In an exemplary embodiment, as shown in FIG12 , a multi-leaf grating displacement detection device is provided, comprising: a data acquisition module 1201, a creep monitoring module 1202 and a displacement determination module 1203, wherein:

[0156] The data acquisition module 1201 is used to acquire the contact voltage and full-scale voltage of the thin film potentiometer in at least one sampling batch;

[0157] The creep monitoring module 1202 is used to obtain the creep state of the thin film potentiometer, and compensate the contact voltage based on the creep state of the thin film potentiometer to obtain the compensated contact voltage;

[0158] The displacement determination module 1203 is used to determine the displacement information of the blades in the grating according to the compensated contact voltage and the full-scale voltage.

[0159] Each module in the above multi-leaf grating displacement detection device can be implemented in whole or in part by software, hardware and a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each module.

[0160] In an exemplary embodiment, a multi-leaf grating is further provided, comprising a plurality of blades and the multi-leaf grating displacement detection circuit in any one of the above embodiments, wherein the blades and the grating displacement detection circuit are arranged correspondingly.

[0161] Exemplarily, the blades correspond one-to-one to the thin-film potentiometers in the grating displacement detection circuit.

[0162] In an exemplary embodiment, a medical device is further provided. The medical device includes the multi-leaf collimator according to any one of the above embodiments.

[0163] Optionally, the medical device may be a single-mode radiotherapy (RT) device or a multi-mode RT device, such as Equipment (Image Guide Radiation Therapy, IGRT).

[0164] Among them, IGRT includes not only RT equipment, but also image-guided equipment, such as X-ray tomography system (Computerized Tomography, CT), magnetic resonance (Magnetic Resonance, MR) imaging diagnostic system or positron emission tomography (Positron Emission Tomography, PET) system.

[0165] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the multi-leaf grating displacement detection method in any one of the above embodiments are implemented.

[0166] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the steps of the multi-leaf grating displacement detection method in any one of the above embodiments.

[0167] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0168] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0169] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A multi-leaf grating displacement detection method, characterized in that: A thin film potentiometer is used to measure displacement information of leaves in a multi-leaf grating, and the method comprises: obtaining a contact voltage and a full-scale voltage of a thin-film potentiometer in at least one sampling batch; Acquiring a creep state of the thin film potentiometer, and based on the creep state, compensating the contact voltage to obtain a compensated contact voltage; The displacement information of the blade is determined according to the compensated contact voltage and the full-scale voltage.

2. The method according to claim 1, characterized in that: The step of obtaining the creep state of the thin film potentiometer comprises: Obtaining the resistance change of the thin film potentiometer between adjacent sampling batches; The creep state of the thin film potentiometer is determined according to a comparison result of the resistance change amount and a preset change amount threshold.

3. The method according to claim 1 or 2, characterized in that: The step of obtaining the compensated contact voltage comprises: Obtain the film resistance corresponding to the contact voltage; determine the compensated contact voltage based on the relationship between the film resistance and the creep characteristic of the film potentiometer; the creep characteristic relationship is used to characterize the corresponding relationship between the resistance change caused by creep and the creep duration.

4. The method according to claim 3, characterized in that: Determining the compensated contact voltage according to the relationship between the film resistance and the creep characteristic of the film potentiometer includes: Determining a resistance change corresponding to a creep time length of the contact voltage based on the creep characteristic relationship; Obtaining a resistance difference between the film resistance and the resistance change; The compensated contact voltage is determined according to the resistance difference and the input current of the thin film potentiometer.

5. A multi-leaf grating displacement detection circuit, characterized in that: The multi-leaf grating displacement detection circuit comprises: A constant current source circuit (101), a thin film potentiometer (102), an analog switch circuit (103), a sampling circuit (104), and a control circuit (105); a sliding contact in the thin film potentiometer (102) is arranged on a blade of a multi-leaf grating, and the blade can drive the sliding contact to move on the thin film resistor of the thin film potentiometer (102); The constant current source circuit (101) is used to generate an input current, and the analog switch circuit (103) is used to be turned on under the control of the control circuit (105), so that the sampling circuit (104) samples and obtains the contact voltage and full-scale voltage of the thin film potentiometer (102); The control circuit (105) is used to obtain the creep state of the thin film potentiometer (102), and based on the creep state, compensate the contact voltage to obtain the compensated contact voltage, and determine the displacement information of the blade according to the compensated contact voltage and the full-scale voltage.

6. The multi-leaf grating displacement detection circuit according to claim 5, characterized in that: The grating displacement detection circuit also includes a voltage follower filter circuit (106), wherein the voltage follower filter circuit (106) is connected between the analog switch circuit (103) and the sampling circuit (104) and is used for signal filtering.

7. The multi-leaf grating displacement detection circuit according to claim 6, characterized in that: The voltage follower filter circuit (106) comprises an operational amplifier, a first capacitor, a second capacitor, a first resistor and a second resistor; the first capacitor and the second resistor are connected in parallel, one end of the first capacitor and the second resistor are respectively connected to the input end of the operational amplifier, and the other end of the first capacitor and the second resistor are respectively connected to the output end of the operational amplifier; the first resistor is connected to the output end of the operational amplifier; one end of the second capacitor is connected to the output end of the operational amplifier, and the other end is grounded.

8. A multi-leaf grating displacement detection device, characterized in that: A thin film potentiometer is used to measure the displacement information of leaves in a multi-leaf grating, and the device comprises: A data acquisition module (1201) is used to acquire a contact voltage and a full-scale voltage of a thin film potentiometer in at least one sampling batch; A creep monitoring module (1202) is used to obtain the creep state of the thin film potentiometer, and based on the creep state of the thin film potentiometer, compensate the contact voltage to obtain the compensated contact voltage; A displacement determination module (1203) is used to determine the displacement information of the blades in the grating according to the compensated contact voltage and the full-scale voltage.

9. A multi-leaf grating, characterized in that: The multi-leaf grating includes a plurality of blades and a grating displacement detection circuit as described in any one of claims 5 to 7, and the blades are arranged corresponding to the grating displacement detection circuit.

10. A medical device, characterized in that: The medical device comprises the multileaf collimator according to claim 9.

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