Methods for determining the location of radiotherapy device components

Abstract

Methods, apparatus, and computer-readable media for determining the position of components of a radiotherapy apparatus are disclosed. One method for determining the position of a component of a radiotherapy apparatus includes obtaining indications of displacement of the component from a plurality of sensors. The position of the component can be determined based on two of the displacement indications.

Description

Technical Field

[0001] This disclosure relates to methods, apparatus, devices, systems, and computer-readable media for radiotherapy, and particularly to, but not limited to, methods, apparatus, and / or computer-readable media for determining the location of components of a radiotherapy apparatus. Background Technology

[0002] Radiation therapy can be described as using ionizing radiation (such as X-rays) to treat the body of a human or animal. Radiation therapy is commonly used to treat tumors in human or animal patients or subjects. In this treatment, ionizing radiation is used to irradiate and thus destroy or damage the cells that form part of the tumor.

[0003] Radiation therapy devices are highly complex machines with numerous intricately interacting subsystems. Precise mechanical control of many components is crucial for effective radiation therapy. More accurate and / or precise component positioning allows radiation therapy to target tumors more effectively and can reduce the amount of radiation exposed to healthy tissue. However, determining the location of one or more of those components with high precision or high resolution can be challenging and highly technical. Summary of the Invention

[0004] The invention is described in the claims. Attached Figure Description

[0005] Now, we will describe a specific example with reference to the accompanying drawings, in which:

[0006] Figure 1 The radiotherapy device is shown;

[0007] Figure 2 A device for determining the position of components of a radiotherapy apparatus is shown;

[0008] Figure 3 A flowchart is shown showing a method for determining the location of components of a radiotherapy device;

[0009] Figure 4 A graph showing exemplary displacement indication data obtained from three sensors is shown;

[0010] Figure 5 A block diagram illustrating one implementation of a radiotherapy system is shown; and

[0011] Figure 6 This illustrates a computer-readable medium or, more generally, a computer program product. Detailed Implementation

[0012] Figure 1A radiotherapy apparatus 100 or device is shown, adapted to deliver to a patient during radiotherapy treatment and configured to deliver a radiation beam to the patient. The radiotherapy apparatus 100 and its components will be generally described to provide useful accompanying information for this disclosure. Figure 1 The radiotherapy device 100 shown is applicable to the disclosed methods, devices and / or computer-readable media.

[0013] The radiotherapy apparatus 100 is an image-guided radiotherapy (IGRT) machine. The radiotherapy apparatus 100 includes a rotatable gantry 102, a treatment device 104, and an imaging device 106 mounted on the rotatable gantry 102. In this example, the treatment device 104 and the imaging device 106 are attached to the gantry such that they can rotate together with the gantry, i.e., they rotate as the gantry rotates. Positioned within the treatment volume 109 of the radiotherapy apparatus 100 is a patient support surface 110, on which the patient 112 is positioned during radiotherapy treatment.

[0014] The patient support surface 110 is configured to move between a first position substantially outside the treatment volume 109 and a second position substantially inside the treatment volume 109. In the first position, a patient or subject can mount the patient support surface. The patient support surface 110 and the patient can then be moved inside the aperture to reach the second position for imaging or treatment of the patient using the radiotherapy device 100. The movement of the patient support surface is achieved and controlled by a patient support surface actuator, which can be described as an actuation mechanism. These components together can be described as a patient positioning system, which may include other components. The patient support surface may also be referred to as a movable or adjustable couch or platform.

[0015] The treatment device 104 includes a treatment beam source 114 and a treatment beam target 116. The treatment beam source 114 is configured to emit or direct therapeutic radiation, such as megavolt (MV) energy radiation, toward the treatment volume 109 and thus toward the patient 112. As those skilled in the art will understand, the treatment beam source 114 may include an electron source, a linear accelerator (linac) for accelerating electrons toward a heavy metal (e.g., tungsten) target to generate high-energy photons, and a collimator configured to collimate the resulting photons and thereby generate the treatment beam. Once the therapeutic radiation has been emitted from the source 114 and passed through the patient 112, the therapeutic radiation continues toward the treatment beam target 116, where it is blocked / absorbed. The treatment beam target 116 may include an imaging panel (not shown). Thus, the treatment beam target can form part of an electron beam imaging device (EPID). EPID is generally known to those skilled in the art and will not be discussed in detail here.

[0016] Imaging device 106 includes an imaging beam source 118 and an imaging panel 120. Imaging beam source 118 is configured to emit or direct imaging radiation, such as X-rays with kV energy, toward patient 112. As those skilled in the art will understand, imaging beam source 118 may be an X-ray tube or other suitable X-ray source. Imaging beam source 119 is configured to generate kV energy radiation. Once the imaging radiation has been emitted from imaging beam source 118 and passed through patient 112, the imaging radiation continues toward imaging panel 120. Imaging panel 120 may be described as a radiation detector or radiation intensity detector. Imaging panel 120 is configured to generate signals indicating the intensity of radiation incident on imaging panel 120. In use, these signals indicate the intensity of radiation that has passed through patient 112. These signals may be processed to form an image of patient 112. This process may be described as imaging device 106 and / or imaging panel 120 capturing images. By taking images around the patient at multiple angles, such as using tomographic reconstruction techniques, a three-dimensional image of the patient can be generated.

[0017] The imaging beam source 118 can be mounted on the imaging source arm, allowing the imaging beam source 118 to move in a direction parallel to the axis of rotation of the gantry. Thus, the imaging source arm is configured to deploy the imaging beam source 118 to a position away from the gantry (deployed position) for imaging the patient, and is configured to retract the imaging beam source 118 to a position close to the gantry when imaging is not required (retracted position).

[0018] In conventional radiotherapy systems, the imaging arm is manually moved by the operator between an extended and retracted position. The operator can manually slide the imaging arm from the retracted position to the extended position and vice versa. In such known systems, the operator manually locks the arm in the extended or retracted position by manually engaging a latching pin.

[0019] In the example shown, the treatment device 104 and the imaging device 106 are mounted on a rack such that the treatment beam travels in a direction substantially perpendicular to the imaging beam.

[0020] Because the gantry 102 is rotatable, the treatment beam can be delivered to the patient from a range of angles. Similarly, the patient can be imaged by the imaging device 106 from a range of angles. As those skilled in the art will understand, the gantry 102 can be rotated relative to the patient to any of a plurality of discrete angular positions. Depending on the treatment plan, the treatment device 104 can direct radiation toward the patient at each or more of these discrete angular positions. The treatment device 104 can even be used to continuously irradiate the patient at all rotational angles as the gantry 102 rotates. The angle at which radiation is applied, as well as the intensity and shape of the treatment beam, can depend on the specific treatment plan associated with a given patient.

[0021] The radiotherapy apparatus 100 also includes a controller (not shown). The controller includes a computer, processor, and / or other processing devices configured to control the radiotherapy apparatus 100. The controller is configured to send control signals to various components of the radiotherapy apparatus 100, such as those described above and elsewhere herein. The controller is also configured to send control signals to the treatment equipment to implement changes during radiotherapy treatment. The controller also collects data indicative of the performance and operation of the various components of the radiotherapy apparatus 100. For example, the controller controls the rotation of the gantry and records the angle to which the gantry has been rotated.

[0022] The controller may be formed of several discrete processors; for example, the controller may include an imaging device processor for controlling the imaging device 106; a treatment device processor for controlling the operation of the treatment device 104; and a patient support surface processor for controlling the operation and actuation of the patient support surface 110. The controller is communicatively coupled to a memory, such as a computer-readable medium, which includes computer-executable instructions executable by the controller. The computer-executable or computer-readable instructions may cause the processor to perform any one or more of the methods disclosed herein.

[0023] The radiotherapy apparatus 100 also includes several other components and systems as those skilled in the art will understand. For example, appropriate shielding is provided to ensure that the linear accelerator does not leak radiation.

[0024] Therefore, movable components of a radiotherapy apparatus may include, but are not limited to, patient support surfaces, imaging source arms and / or imaging beam sources, as well as rotatable moving parts (e.g., gantry and components mounted thereon). Precise control and / or determination of the position of each of these components enables the delivery of more effective radiotherapy. For components such as imaging source arms and imaging beam sources mounted thereon, highly precise control and / or determination of position over a relatively long range of displacement or motion may be required. Position sensors can be used to monitor, detect, and / or determine the position of the imaging beam source along its range of motion. However, sensors with particularly high accuracy or high position resolution capabilities over a relatively long range of displacement are typically expensive and have stringent data throughput requirements. Generally, sensors with shorter measurement distances have higher measurement accuracy, while sensors with longer measurement distances have lower measurement accuracy. Furthermore, to obtain data from long-distance, high-precision sensors, particularly high-performance and expensive analog-to-digital converters (ADCs) are typically required. Moreover, certain types of position sensors may be affected by X-ray radiation from the radiotherapy apparatus.

[0025] Figure 2A sensing device 200 for determining the position of a component 201 of a radiotherapy apparatus, according to the present disclosure, is shown. Component 201 may correspond to any suitable movable part of the radiotherapy apparatus. The sensing device 200 can provide relatively high accuracy and / or position resolution capability over a relatively long displacement range of the components of the radiotherapy apparatus.

[0026] Component 201 is arranged to be movable along path 203. Path 203 may be a mechanical component, such as... Figure 2 The example track is of fixed length, or it could be an extendable and retractable mechanical component. In some examples, component 201 can move or displace linearly along path 203, for example, by using linear translation of a motor. Path 203 provides a range of motion 205 or a range of displacement extending between base 207 and the endpoint of range of motion 205. It should be understood that in some examples, the endpoint of range of motion 205 may correspond to the end of path 203, and in other examples, the endpoint of range of motion 205 may deviate from the width of component 201 from the end of path 203 along the direction of path 203, such that in these examples, the effective maximum displacement of component 201 from base 207 can reduce the width of component 201. In some examples, the path may not correspond to translational movement of the component, but may correspond to a displacement path caused by rotation of the component.

[0027] Sensing device 200 includes a first sensor 209, a second sensor 211, and a third sensor 213. The first sensor 209 is arranged to sense and / or obtain a first indication 210 of the displacement of component 201 in the direction in which component 201 has moved or is moving along path 203 (which may be referred to herein as the "first direction"). The second sensor 211 is arranged to sense and / or obtain a second indication 212 of the displacement of component 201 in the direction in which component 201 has moved or is moving along path 203, the same direction as the first indication 210. The third sensor 213 is arranged to sense and / or obtain a third indication 214 of the displacement of component 201 in the direction in which component 201 has moved or is moving along path 203, the same direction as the first indication 210 and the second indication 212. Figure 2 In the example, the first direction corresponds to the direction indicated by the arrows of each of the first indicator 210, the second indicator 212, and the third indicator 214. However, it should be understood that the component 201 may also, or alternatively, be able to move along the path 203 toward the sensors 209, 211, 213 in the opposite direction, and each sensor 209, 211, 213 may also, or alternatively, be arranged to sense and / or obtain a corresponding indication of the displacement of the component 201 in that opposite direction.

[0028] Each sensor 209, 211, 213 can be a position sensor or a position-encoded sensor. For example, each corresponding indication of the displacement of component 201 can represent an absolute or relative position along path 203 encoded by the corresponding sensor.

[0029] The first sensor 209, the second sensor 211, and the third sensor 213 each have their own displacement indication range. For example, the first sensor 209 may have a displacement indication range from 0 to 1 meter, the second sensor 211 may have a displacement indication range from 0 to 10 centimeters, and the third sensor 213 may also have a displacement indication range from 0 to 10 centimeters.

[0030] As an illustrative example, the first sensor 209, the second sensor 211, and the third sensor 213 may each be based on a corresponding rotary potentiometer. As those skilled in the art will appreciate, a rotary potentiometer exhibits variable resistance as a function of rotation and is typically arranged with a bent and / or annular resistive element, which may be arc-shaped or annular with discontinuities or gaps in its circumference. A rotatable or swiper on a shaft or dial may be arranged to contact the resistive element, allowing it to rotate and thus move along the resistive element. The rotary potentiometer may also typically have an electrical connection pin on either side of the bent resistive element, and a third electrical connection pin connected to the shaft and / or the wiper. When the wiper rotates, it changes position along the circumference of the resistive element, thereby producing a change in resistance. Therefore, the rotary potentiometer can function as a voltage divider and output a voltage change corresponding to the change in resistance produced when the wiper changes position on the resistive element. Alternatively, a fixed voltage may be applied such that the change in resistance within the variable potentiometer produces a change in current according to Ohm's law. As will be known to those skilled in the art, a variable potentiometer may also be provided with an extendable or pullable string or wire to convert displacement into rotation of a sliding contact. Thus, a rotary potentiometer can provide an indication of displacement corresponding to a variable resistance.

[0031] In a rotary potentiometer arranged in this manner, the sliding contact may need to rotate more than one full revolution around the circumference of the resistive element for a given displacement, and the variable resistance measurable from the rotary potentiometer will reset with each full revolution or rotation. The terms "single-turn sensor" and / or "single-turn potentiometer" may be used herein to describe sensors having this "reset" characteristic. It should be understood that such a "single-turn" potentiometer can be mechanically rotated multiple revolutions, but the variable resistance of the potentiometer corresponds to the variable resistance of a single turn in each revolution.

[0032] Each of the second sensor 211 and the third sensor 213 can be a "single-turn" sensor and can be arranged to generate an output signal (e.g., voltage or current) for a displacement range that corresponds to a displacement greater than or more than the displacement indication range covered by the corresponding sensor. In such an example, the output signal can be arranged to vary proportionally to the displacement across the voltage or current range, such that each endpoint of the voltage or current range corresponds to an endpoint of the displacement indication range. When the physical displacement of the component increases beyond the displacement corresponding to the endpoint of the sensor's displacement indication range, the corresponding sensor can continue to generate an output signal as the displacement increases, but the amplitude or value of the output signal will return to its original value and then vary again within the limits of the voltage or current range with further displacement, as in the example of a sliding contact rotating multiple times around the circumference of a resistive element.

[0033] As an illustrative example, each of the second and third sensors may include a potentiometer, such as a drawstring potentiometer (also known as a "draw wire" potentiometer) comprising an extendable string (or wire). The extendable string may be attached to component 201, and the potentiometer may be arranged to output a voltage signal indicating the displacement of the component, the voltage signal varying between 0 and 10V with each turn of the potentiometer. Thus, a single turn of the potentiometer will result in an output signal varying between 0 and 10V, corresponding to the displacement indication range of the sensor. However, each turn of the potentiometer may correspond to, for example, a displacement value of 10 centimeters, and the string of the potentiometer may be arranged to extend 1 meter. Therefore, extending the string within a 1-meter range will cause the potentiometer to rotate through multiple full turns, resulting in the sensor's output signal varying between 0 and 10V for every 10 centimeters of displacement, for a total of ten repeating intervals, each interval corresponding to the displacement indication range of the sensor.

[0034] In certain types of rotary potentiometers (referred to in the art as “multi-turn potentiometers”), a helical resistive element can be used, and the sliding contact can move continuously along the helical shape of the resistive element as the sliding contact rotates multiple times, thus providing a continuous change in measurable resistance over multiple turns, rather than a resistance change that necessarily resets with each full turn of the sliding contact. Although sensors and / or potentiometers capable of multiple turns or rotations are described herein, unless so specified, those sensors and / or potentiometers do not necessarily correspond to “multi-turn potentiometers” having continuously variable resistance over those multiple turns.

[0035] In some examples, the first sensor 209 is arranged such that the displacement indication range of the first sensor corresponds to the displacement range in which the first sensor is arranged to generate an output signal. For example, the first sensor may include a pull-cord multi-turn potentiometer, such as a potentiometer comprising a helical resistive element. In such an example, the displacement indication range of the first sensor may correspond to a range of 0 to 1 meter, the first sensor may be arranged to sense displacements up to 1 meter, and the output signal of the first sensor may vary between 0V and 10V within this 1-meter range. Those skilled in the art will understand that the specific values ​​of voltage and displacement provided herein are merely non-limiting examples, and sensors with other values ​​may be used.

[0036] Multiple indications of component displacement obtained from multiple corresponding sensors enable the combination of sensors with different properties to determine the component's position. The first sensor 209 may be of a first type, having relatively low measurement accuracy or resolution over a relatively long displacement range and / or displacement indication range, and each of the second sensor 211 and the third sensor 213 may be of a second type, having relatively high measurement accuracy or resolution over a correspondingly relatively short displacement range and / or corresponding displacement indication range. Further use... Figure 3 and Figure 4 As the example illustrates, multiple indications of displacement from different sensors can be used to determine the position of a component with improved accuracy compared to using a single sensor, and can also be used to do so over a relatively long range of displacement of the component.

[0037] exist Figure 2 In one example, each sensor 209, 211, 213 is placed or mounted at the base 207. However, in other examples, one or more of sensors 209, 211, 213 may alternatively be mounted elsewhere, such as at the end of the range of motion 205. Each sensor 209, 211, 213 may be mounted at any location that allows the sensor to sense the positioning and / or location of component 201. Thus, the sensing device 200, including three sensors 209, 211, 213, can be suitably arranged to determine the location of any component of the radiotherapy apparatus capable of moving or displacing along a path. In other examples, determining the location of a component may include using the sensing device 200 to determine the rotational position of the component. For example, the component is not necessarily arranged to translate or displace along a path, but may alternatively or additionally be arranged to rotate about an axis. The sensing device 200 may be used to obtain an indication of the displacement of the component caused by its rotation, thereby enabling the determination of the rotational position of the component.

[0038] In some examples, component 201 may be an imaging component, such as an imaging source arm and / or imaging beam source of a radiotherapy apparatus, such as Figure 1Those are examples of radiotherapy devices 100. For example, component 201 may correspond to an imaging beam source, and path 203 may be provided by a deployable imaging source arm. In some radiotherapy devices, an imaging detector, such as imaging panel 120, may be mounted on a deployable and retractable arm similar to an imaging source arm. In such examples, alternatively or additionally, devices similar to... Figure 2 The sensing device determines the position and / or orientation of the imaging panel. Therefore, the sensing device 200 can typically be used to determine the position of the imaging components or imaging arm of a radiotherapy apparatus.

[0039] Figure 3 A flowchart illustrates a method 300 for determining the position of components of a radiotherapy apparatus. Method 300 may utilize a sensing device 200. Method 300 may be applied to determine the position of components (e.g., Figure 2 The position of component 201). Method 300 can be a computer-implemented method.

[0040] At block 302, method 300 includes receiving a first indication of displacement of the component in a first direction, a second indication of displacement of the component in the first direction, and a third indication of displacement of the component in the first direction, the first indication, the second indication, and the third indication having been obtained from corresponding first, second, and third sensors, each having a corresponding displacement indication range. The first, second, and third sensors may respectively correspond to... Figure 2 The sensing device 200 has sensors 209, 211, and 213. A first indication, a second indication, and a third indication can be received from each corresponding sensor.

[0041] At block 304, the method includes determining that a second indication of displacement is within a predetermined portion of the displacement indication range of the second sensor.

[0042] A predetermined portion of the displacement indication range may correspond to a portion of the displacement indication range for which the second sensor has been determined to be less reliable. For example, the second sensor may have a "dead zone," which is the output range of the sensor that is less reliable or unreliable. Referring to an illustrative example of a rotary potentiometer, the dead zone of such a sensor may correspond to a specific portion of a bent resistive element where the sliding contact cannot maintain contact with the bent resistive element, and therefore no indicative electrical output can be obtained from the rotary potentiometer when the sliding contact is in that position. For example, if the bent resistive element is an annular ring with a gap in its circumference, the output signal when the sliding contact is located at or near the gap may correspond to the sensor's dead zone. The dead zone may also, or alternatively, correspond to a portion of the circumference of the resistive element containing the point where the sensor's output signal will indicate zero displacement.

[0043] In some examples of method 300, a predetermined portion of the displacement indication range of the second sensor corresponds to the dead zone of the second sensor. The dead zone or other predetermined portion can be determined, for example, during the manufacture of the sensor, and therefore determined or predetermined before performing method 300. If the second indication is not within the predetermined portion of the displacement indication range of the second sensor, the position of the component can be determined based on the first and second indications. However, since the second indication within the predetermined portion may be unreliable, the method disclosed herein provides a third indication from a third sensor.

[0044] At box 306, the method includes: therefore, determining the position of the component based on the first indication and the third indication.

[0045] Method 300 determines the position of a component by allowing the combination of indications from a longer-range, lower-precision sensor with indications from a shorter-range, higher-precision sensor, thereby gaining the advantages of each type of sensor and improving the overall accuracy or resolution of the determined position. Position can be determined with higher accuracy compared to using either sensor alone, and it is less costly and less complex than using a long-range, high-precision sensor.

[0046] Furthermore, by determining that the second indication is within a predetermined portion of the displacement indication range of the second sensor and utilizing the third indication from the third sensor, less reliable or unreliable indications from the second sensor can be avoided, and the third indication can be used instead, thereby providing improved accuracy determination over the entire range of motion of the component rather than just a portion thereof. Therefore, method 300 provides a general method for determining the position of components of a radiotherapy apparatus with improved accuracy.

[0047] In some examples of method 300, the first sensor is arranged to indicate displacement at a lower resolution than each of the second and third sensors. For example, the first sensor may be arranged to sense and indicate displacement using an analog-to-digital converter (ADC) with a mapping of 0 to 100 data points for a displacement indication range of 0 to 1000 mm, while each of the second and third sensors may be arranged to sense and indicate displacement using an ADC with a mapping of 0 to 100 data points for a displacement indication range of 0 to 10 mm. In this arrangement, the first sensor is thus arranged to indicate displacement at a lower resolution than each of the second and third sensors. It should be understood that in other examples, different values ​​of data points may be used for each ADC, or an ADC may not be used at all.

[0048] In some examples of method 300, each sensor is arranged to provide an indication of displacement using a corresponding analog-to-digital converter. In some examples of method 300, each of the first, second, and third sensors may include an analog-to-digital converter, each corresponding analog-to-digital converter having the same conversion resolution. In some examples of method 300, each of the first, second, and third sensors may include an analog-to-digital converter, each corresponding analog-to-digital converter having the same sampling rate.

[0049] In some examples of method 300, the displacement indication range of the first sensor corresponds to a displacement larger than the corresponding displacement indication range of each of the second and third sensors. In some examples, the second and third sensors each have the same displacement indication range, and in other examples, the second and third sensors have different displacement indication ranges from each other.

[0050] In some examples of method 300, each of the second and third sensors is arranged to generate a corresponding output signal to indicate displacement, each output signal having a corresponding relationship between the value of the output signal and the displacement, each relationship comprising a plurality of repeating intervals, wherein each interval corresponds to the displacement indication range of the corresponding sensor. In examples where the sensors include an ADC, it should be understood that the “output signal” may correspond to an analog signal provided as input to the ADC, and the output of the ADC (which may correspond to the final output of the sensor) will be based on and proportional to that analog signal.

[0051] Within each interval, the value (or amplitude) of the output signal can follow a relationship with displacement, corresponding to the change in the output signal with displacement within the displacement indication range of the corresponding sensor. Therefore, the corresponding sensor can be arranged to sense displacement within a range comprising a series of discrete such intervals. For example, a sensor with a displacement indication range of 0 to 10 cm can produce, for example, an output signal of 0V corresponding to 0 cm and 10V corresponding to 10 cm. However, in this example, the sensor can be arranged with a string or wire that extends beyond a displacement range of 10 cm. When the sensed radiotherapy device component displaces beyond 10 cm and the string or wire thus extends beyond 10 cm, the value or amplitude of the sensor's output signal will not further increase to more than 10V, but will instead “restart” from 0V and increase again from 0V to 10V in the next 10 cm displacement. This will repeat as the displacement further increases, with each iteration corresponding to every additional 10 cm of extension or displacement. In the example using a potentiometer, each iteration could correspond to a complete loop of the potentiometer, as described above regarding... Figure 2As described in the illustrative example of a "single-turn potentiometer". Therefore, the amplitude or value of the output signal can be considered to have a cyclic or periodic relationship with the displacement, where each cycle of the cyclic relationship is a discontinuous repetition of a voltage range corresponding to the displacement indication range of the sensor.

[0052] In some examples of method 300, a phase difference exists between the output signal of the second sensor and the output signal of the third sensor, optionally wherein the phase difference is approximately 60°. For example, the relationship between the output signal of the second sensor and the displacement may have a phase offset compared to the relationship between the output signal of the third sensor and the displacement. Such an arrangement is particularly advantageous for enabling the acquisition of indications from at least one of the higher-resolution second or third sensors for use over the entire displacement range of the component, and a phase difference or offset of approximately 60° has been found particularly advantageous for avoiding displacement values, for example, where both the second and third sensors are in less reliable predetermined portions or dead zones. In other examples, another amount of phase difference may be used to avoid displacement values, for example, where both the second and third sensors are in less reliable predetermined portions or dead zones. Generally, any phase difference value may be used, as long as the difference is not so small or so large that there is overlap between the corresponding less reliable predetermined portions or dead zones of the second and third sensors at a particular displacement.

[0053] In some examples of method 300, a first sensor is arranged to generate an output signal to indicate displacement in a first direction, the output signal of the first sensor having a substantially linear proportional relationship with the displacement.

[0054] In some examples of method 300, there is essentially no phase difference between the output signal of the first sensor and the output signal of the second sensor.

[0055] In some examples of method 300, determining the position of a component includes: using a first indication to determine the coarse-resolution position of the component, and using a third indication to determine the fine-resolution position of the component.

[0056] So far, method 300 has been described with reference to an example where a component is positioned corresponding to a second displacement indication falling within a predetermined portion of the displacement indication range of the second sensor, and thus the position of the component is determined based on the first and third indications. However, the same component may be moved to one or more other positions, for which the second sensor will generate an indication of displacement not falling within the predetermined portion of the displacement indication range of the second sensor. In these positions of the component, the second sensor can be considered reliable and can be used to determine the position of the component.

[0057] Therefore, in some examples, method 300 further includes: receiving a fourth indication of displacement of the component in a first direction, a fifth indication of displacement of the component in the first direction, and a sixth indication of displacement of the component in the first direction, the fourth, fifth, and sixth indications having been obtained from a first, second, and third sensor, respectively; determining that the fifth indication of displacement is not within a predetermined portion of the displacement indication range of the second sensor; and thus determining the position of the component based on the fourth and fifth indications. Such examples enable the indication from the second sensor to be used to determine a subsequent position of the component in which the second indication does not fall within a predetermined portion of the displacement indication range of the second sensor.

[0058] In some examples of method 300, at least one of the first, second, and third sensors is arranged to convert rotational motion into an indication of displacement. In some examples of method 300, at least one of the first, second, and third sensors includes a potentiometer. In some examples of method 300, at least one of the first, second, and third sensors includes a draw-wire potentiometer. In other examples, another type of sensor may be used for at least one of the first, second, and / or third sensors, such as an optical sensor, a mechanical sensor, or a non-rotational potentiometer sensor.

[0059] In some examples of method 300, the first sensor may include a multi-turn potentiometer, such as a potentiometer comprising a helical resistive element.

[0060] In some examples, method 300 further includes determining the corresponding number of rotations of the second and / or third sensors based on a first indication. In some examples of method 300, determining the position of components of the radiotherapy apparatus is based on adding a third indication of displacement to the displacement corresponding to the number of rotations the third sensor has undergone, said number of rotations being determined from the first indication.

[0061] In some examples of method 300, the component is the imaging component of the radiotherapy device.

[0062] Now will be used Figure 4 To explain Figure 3 An exemplary implementation of method 300.

[0063] Figure 4A graph 400 illustrates exemplary displacement indication data obtained by a first sensor, a second sensor, and a third sensor according to the method disclosed herein. In this example, each of the three sensors is a draw-wire potentiometer, arranged to output voltage for a displacement range of 0 to 1000 mm. A first subgraph 402 corresponds to the output W of the first sensor in this displacement range, a second subgraph 404 corresponds to the output W1 of the second sensor in this displacement range, and a third subgraph 406 corresponds to the output W2 of the third sensor in this displacement range. In each subgraph, the vertical axis represents the voltage output of the sensor, and the horizontal axis represents the displacement. Each output W, W1, W2 can be considered to correspond to a corresponding indication of displacement obtained by and available from the respective sensor.

[0064] The first sensor, the second sensor, and the third sensor can correspond to Figure 2 and Figure 3 The example shows the first, second, and third sensors. Figure 4 In the example, the first sensor includes a multi-turn potentiometer (e.g., a potentiometer including a helical resistive element), and the second and third sensors each include a single-turn potentiometer. The first sensor provides an indication of displacement with a lower resolution than each of the second and third sensors.

[0065] Figure 4 Graph 400 illustrates corresponding indications of displacement that can be obtained from the respective sensors and upon which the position of the components can be determined. Four exemplary displacement positions of the components of the radiotherapy device are shown on graph 400, points p1, p2, p3, and p4. At each displacement point, [the following information can be used]. Figure 3 Method 300 is used to determine the location of components of a radiotherapy device.

[0066] At each displacement point, a first indication is obtained according to the first sub-figure 402. For example, at p1, the first indication of the first sensor is an output voltage of 2.5V, indicating a displacement of approximately 250mm. Therefore, a general or coarse-resolution position of the component is obtained from the first indication. A fine-resolution position of the component can be obtained using one or both of the second and third indications of the corresponding second sub-figures 404 and third sub-figures 406.

[0067] Since the second and third sensors are each single-turn sensors, the method may include: determining, based on a first indication, how many revolutions or circles the second and / or third sensors have rotated for a given displacement. For example, when the output of the first sensor is in the range of 0 to 1V, each of the second and third sensors is in the first revolution; while when the output of the first sensor is in the range of 2 to 3V, each of the second and third sensors is in the third revolution.

[0068] According to block 304 of method 300, it can be determined from the data in the second sub-figure 304 whether a second indication of displacement is within a predetermined portion of the displacement indication range of the second sensor. In this example, the output of W1 in the range of 1V to 9V is not in the dead zone, and therefore is not within the predetermined portion of the displacement range of the second sensor. At points p1 and p2, the second indication from the second sensor is not in the dead zone and can be used to provide a fine-resolution position indication of the position of the sensed component. The position of the component can be determined as equal to the displacement indication provided by W1 plus the displacement corresponding to the number of revolutions the second sensor has rotated, which is determined from the displacement indication output W of the first sensor. In particular, the position can correspond to the current value of the indication from the second sensor plus an additional amount, which includes the number of revolutions N of the second sensor multiplied by the voltage corresponding to the maximum value of the displacement indication range (10V in this example). In other words, the position of the component can be determined to correspond to W1 + N*10V.

[0069] On the other hand, in this example, if the output W1 of the second sensor is less than 1V or greater than 9V, the second indication determining the displacement is within the dead zone, and therefore within a predetermined portion of the displacement indication range of the second sensor. Points p3 and p4 illustrate such an example. Indications from the second sensor, which is in its dead zone, may be unreliable; therefore, the third sensor is arranged to have a known phase difference compared to the second sensor, such that at a given displacement point, at most one of the second and third sensors will be in its dead zone. Thus, the position of the component can be determined based on the first and third indications. In this example, the third sensor is considered to have the same dead zone as the second sensor, less than 1V or greater than 9V. From Figure 4 It can be seen that at points p3 and p4, the output W2 of the third sensor is in the range of 1V to 9V, and therefore is not in the dead zone.

[0070] Therefore, the positions of the radiotherapy apparatus components can be determined based on the coarse-resolution indication from the first sensor and the fine-resolution indication from the third sensor. In this case, to provide accurate determination of the component positions when the second sensor is within its dead zone, the position can be determined as equal to the indication provided by W2 plus the displacement corresponding to the number of rotations that the second or third sensor has completed (the number of rotations itself is determined from the W output of the first sensor), and also taking into account the phase difference offset correction between W1 and W2 (and / or between W2 and W).

[0071] exist Figure 4In this specific example, the first sensor uses an analog-to-digital converter (ADC) with a data mapping of 0 to 100 for voltage W. The second and third sensors each use ADCs with a data mapping of 0 to 100 for the corresponding W1 or W2 voltage, which is repeated 10 times over a 1000-meter displacement range. In this example, the phase difference or offset between W1 and W2 is 60°, corresponding to an offset value of 16.6 or 16.6 mm.

[0072] If the value of W2 is greater than the offset value, the offset correction to be applied to the indication of W2 is equal to: W2 - offset value. If the value of W2 is less than the offset value, the offset correction to be applied to the indication of W2 is equal to: 100 - (offset value - W2).

[0073] Therefore, the position of the component at each of points p1, p2, p3, and p4 can be determined as follows.

[0074] p1: W = 25 (2.5V)

[0075] W1 = 40 (4V, and not within the dead zone)

[0076] N = W / 10 = 25 / 10 = 2 (Number of complete revolutions of the second sensor)

[0077] Position = W1 + N*100 = 40 + 2*100 = 240 mm

[0078] p2: W = 57 (5.7V)

[0079] W1 = 70 (7V, and not within the dead zone)

[0080] N = W / 10 = 57 / 10 = 5 (Number of complete revolutions of the second sensor)

[0081] Location = W1 + N*100 = 70 + 5*100 = 570 mm

[0082] p3: W = 79.5 (7.95V)

[0083] W1 = 95 (9.5V, within the dead zone)

[0084] W2 = 12.5 (1.25V, and not within the dead zone)

[0085] N = W / 10 = 79.5 / 10 = 7 (Number of complete revolutions of the second sensor)

[0086] Position = 100 - (Offset - W2) + N*100 = 100 – (16.6-12.5) + 700 = 795.9mm

[0087] p4: W = 90.5 (9.05V)

[0088] W1 = 5 (0.5V, within the dead zone)

[0089] W2 = 20.7 (2.07V, and not within the dead zone)

[0090] N = W / 10 = 90.5 / 10 = 9 (Number of complete revolutions of the second sensor)

[0091] Position = (W2 - Offset) + N*100 = (20.7 - 16.6) + 900 = 904.1 mm

[0092] The method disclosed herein enables precise detection of part position within 0.1 mm over a travel range of 1000 mm and / or 1350 mm. Combining the sensor and ADC as in this example, even using an ADC component with only (0:100) mapping, efficient (0:1000) mapping for a displacement range of 0 to 1000 mm can be achieved. Therefore, relative accuracy can be improved by up to ten times at a lower cost compared to using a single ADC that is ten times more efficient.

[0093] Figure 5 A block diagram illustrating one implementation of a radiotherapy system 500 is shown. The radiotherapy system 500 includes a computing system 510, within which a set of instructions can be executed to cause the computing system 510 to perform any one or more methods discussed herein.

[0094] The computing system 510 should be considered as including any number or set of machines, such as computing devices, that individually or jointly execute a set (or more) of instructions to perform any one or more methods discussed herein. That is, the hardware and / or software may be housed in a single computing device or distributed across multiple computing devices within the computing system. In some implementations, one or more elements of the computing system may be connected to other machines (e.g., via a network), such as in a local area network (LAN), intranet, extranet, or the Internet. One or more elements of the computing system may operate as a server or client machine in a client-server network environment, or as peer machines in a peer-to-peer (or distributed) network environment. One or more elements of the computing system may be a personal computer (PC), tablet computer, set-top box (STB), personal digital assistant (PDA), cellular phone, network device, server, network router, switch, or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) specifying the actions to be taken by that machine.

[0095] The computing system 510 includes controller circuitry 511 and memory 513 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM)). Memory 513 may include static memory (e.g., flash memory, static random access memory (SRAM)) and / or auxiliary memory (e.g., data storage devices), which communicate with each other via a bus (not shown).

[0096] Controller circuit 511 represents one or more general-purpose processors, such as microprocessors, central processing units, accelerated processing units, etc. More specifically, controller circuit 511 may include complex instruction set computing (CISC) microprocessors, reduced instruction set computing (RISC) microprocessors, very long instruction word (VLIW) microprocessors, processors implementing other instruction sets, or processors implementing combinations of instruction sets. Controller circuit 511 may also include one or more special-purpose processing devices, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), network processors, etc. The one or more processors of the controller circuit may have a multi-core design. Controller circuit 511 is configured to execute processing logic for performing the operations and steps discussed herein.

[0097] The computing system 510 may also include network interface circuitry 518. The computing system 510 may be communicatively coupled to input device 520 and / or output device 530 via input / output circuitry 517. In some implementations, input device 520 and / or output device 530 may be elements of the computing system 510. Input device 520 may include alphanumeric input devices (e.g., a keyboard or touchscreen), cursor control devices (e.g., a mouse or touchscreen), audio devices such as a microphone, and / or haptic input devices. Output device 530 may include audio devices such as speakers, video display units (e.g., liquid crystal displays (LCDs) or cathode ray tubes (CRTs)), and / or haptic output devices. In some implementations, input device 520 and output device 530 may be configured as a single device or as separate devices.

[0098] In some implementations, the computing system 510 may include image processing circuitry 519. Image processing circuitry 519 may be configured to process image data 580 (e.g., image or imaging data), such as medical images obtained from one or more imaging data sources, treatment device 550, and / or image acquisition device 540. Image processing circuitry 519 may be configured to process or preprocess image data. For example, image processing circuitry 519 may convert received image data into a specific format, size, resolution, etc. In some implementations, image processing circuitry 519 may be combined with controller circuitry 511.

[0099] In some implementations, the radiotherapy system 500 may also include an image acquisition device 540 and / or a treatment device 550, such as those described herein. Figure 1 The examples disclosed herein are examples of those that may be used. The image acquisition device 540 and the treatment device 550 may be configured as a single device. In some implementations, the treatment device 550 is configured to perform imaging, for example, in addition to providing treatment and / or during treatment. The treatment device 550 includes the main radiation delivery components of a radiotherapy system, such as the beam generation system and linear accelerator components disclosed herein.

[0100] The image acquisition device 540 can be configured to perform positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging (MRI).

[0101] Image acquisition device 540 can be configured to output image data 580, which can be accessed by computing system 510. Treatment device 550 can be configured to output treatment data 560, which can be accessed by computing system 510.

[0102] The computing system 510 can be configured to access or obtain treatment data 560, planning data 570, and / or image data 580. Treatment data 560 can be obtained from an internal data source (e.g., from memory 513) or from an external data source (e.g., treatment device 550 or an external database). Planning data 570 can be obtained from memory 513 and / or from an external source (e.g., a planning database). Planning data 570 may include information obtained from one or more of the image acquisition device 540 and the treatment device 550.

[0103] The various methods described above can be implemented by a computer program. The computer program may include computer code (e.g., instructions) 610 arranged to instruct a computer to perform one or more functions of the various methods described above. The steps of the methods described above can be performed in any suitable order. The computer program and / or code 610 for performing these methods may be on one or more computer-readable media, or more generally in a computer program product 600 (e.g., Figure 6 The computer-readable medium (shown) is provided to a device such as a computer. The computer-readable medium may be temporary or non-temporary. One or more computer-readable media 600 may be, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, or propagation media for data transmission, such as for downloading code via the Internet. Alternatively, one or more computer-readable media may take the form of one or more physical computer-readable media, such as semiconductor or solid-state memory, magnetic tape, removable computer disk, random access memory (RAM), read-only memory (ROM), hard disk, and optical disk, such as CD-ROM, CD-R / W, or DVD. Instructions 610 may also reside wholly or at least partially within memory 513 and / or controller circuitry 511 during execution by computing system 510, which also constitute computer-readable storage media.

[0104] In one implementation, the modules, components and other features described herein may be implemented as discrete components or integrated into the functionality of hardware components such as ASICs, FPGAs, DSPs or similar devices.

[0105] A "hardware component" is a tangible (e.g., non-transitory) physical component (e.g., a collection of one or more processors) capable of performing certain operations and which can be configured or arranged in some physical manner. A hardware component may include dedicated circuitry or logic permanently configured to perform certain operations. A hardware component may include dedicated processors, such as FPGAs or ASICs. A hardware component may also include programmable logic or circuitry temporarily configured by software to perform certain operations.

[0106] Furthermore, modules and components can be implemented as firmware or functional circuitry within a hardware device. Additionally, modules and components can be implemented in any combination of hardware devices and software components, or solely in software (e.g., code stored or otherwise embodied in a machine-readable medium or transport medium).

[0107] Examples of this disclosure can be described herein based on functional and / or logical block components and various processing steps. It should be understood that such block components can be implemented by any number of hardware, software, and / or firmware components configured to perform the specified functions. For example, examples of this disclosure can employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which can perform various functions under the control of one or more microprocessors or other control devices. Furthermore, those skilled in the art will understand that examples of this disclosure can be practiced in conjunction with any number of systems, and the systems described herein are merely exemplary embodiments of this disclosure.

[0108] For the sake of brevity, conventional techniques compared to signal processing, data transmission, signaling, control, and other functional aspects of the system (as well as the various operating components of the system) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures included herein are intended to illustrate exemplary functional relationships and / or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the examples of this disclosure.

[0109] The term “apparatus” as used herein may refer to a single apparatus or multiple apparatuses, and should not be construed as being particularly limited to a single discrete apparatus or multiple discrete apparatuses, unless a particular apparatus is further described in this way.

[0110] Those skilled in the art will recognize that various modifications, alterations, and combinations can be made to the above examples without departing from the scope of the disclosed concepts, and such modifications, alterations, and combinations should be considered to be within the scope of the disclosed concepts.

[0111] Those skilled in the art will also recognize that the scope of the invention is not limited by the examples described herein, but is defined by the appended claims.

Claims

1. A method for determining the position of a component of a radiotherapy device, the method comprising: The system receives a first indication of the displacement of the component in a first direction, a second indication of the displacement of the component in the first direction, and a third indication of the displacement of the component in the first direction. The first indication, the second indication, and the third indication have been obtained from the respective first sensor, second sensor, and third sensor, each having a corresponding displacement indication range; The second indication of displacement is determined to be within a predetermined portion of the displacement indication range of the second sensor; And therefore The position of the component is determined based on the first indication and the third indication.

2. The method of claim 1, wherein, The first sensor is arranged to indicate displacement at a lower resolution than each of the second and third sensors.

3. The method of any preceding claim, wherein, The displacement indication range of the first sensor corresponds to a displacement that is larger than the corresponding displacement indication range of each of the second and third sensors.

4. The method of any preceding claim, wherein, Each of the second and third sensors is arranged to generate a corresponding output signal to indicate displacement, each output signal having a corresponding relationship between the value of the output signal and the displacement, each corresponding relationship including a plurality of repeating intervals, wherein each interval corresponds to the displacement indication range of the corresponding sensor.

5. The method of claim 4, wherein, There is a phase difference between the output signal of the second sensor and the output signal of the third sensor, wherein the phase difference is optionally about 60°.

6. The method of any preceding claim, wherein, The first sensor is arranged to generate an output signal to indicate displacement in the first direction, and the output signal of the first sensor has a substantially linear proportional relationship with the displacement.

7. The method of any preceding claim, wherein, Determining the position of the component includes: using the first indication to determine the coarse-resolution position of the component, and using the third indication to determine the fine-resolution position of the component.

8. The method according to any of the preceding claims, wherein, At least one of the first sensor, the second sensor, and the third sensor is arranged to convert rotational motion into an indication of displacement.

9. The method according to any of the preceding claims, wherein, At least one of the first sensor, the second sensor, and the third sensor includes a potentiometer.

10. The method according to any preceding claim, further comprising: The system receives a fourth indication of the displacement of the component in the first direction, a fifth indication of the displacement of the component in the first direction, and a sixth indication of the displacement of the component in the first direction, wherein the fourth indication, the fifth indication, and the sixth indication have been obtained from the first sensor, the second sensor, and the third sensor, respectively. The fifth indication of displacement is determined to be outside the predetermined portion of the displacement indication range of the second sensor; and therefore The position of the component is determined based on the fourth and fifth indications.

11. The method according to any of the preceding claims, wherein, The predetermined portion of the displacement indication range of the second sensor corresponds to the dead zone of the second sensor.

12. The method according to any of the preceding claims, wherein, The component is the imaging component of the radiotherapy device.

13. An apparatus configured to perform the method of any of the preceding claims.

14. The apparatus according to claim 13, wherein, The device is a radiotherapy device and includes the first sensor, the second sensor, and the third sensor.

15. One or more computer-readable media containing instructions that, when executed by one or more processors, cause to perform the method of any one of claims 1 to 12.

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