Multi-leaf collimator and driving system

The present disclosure relates to a collimator. The collimator may include a motor, a transmission unit having a first end and a second end, and a leaf unit having a leaf. The first end of the transmission unit may be connected to the motor and the second end of the transmission unit may be connected to the leaf. The present disclosure also relates to a collimator system. The collimator system may include a leaf module having a leaf, a driving module having a motor configured to drive the leaf, and a processing module to generate a movement profile of the leaf. The movement profile of the leaf may include a first speed during a first stage, a second speed of the leaf during a second stage, and a third speed of the leaf during a third stage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage under 35 U.S.C. § 371 of International Application No. PCT/CN2016/098620, filed on Sep. 9, 2016, which claims priority of Chinese Patent Application No. 201520698943.6 filed on Sep. 10, 2015 now issued as Chinese Patent No. CN 204972723U, Chinese Patent Application No. 201520699659.0 filed on Sep. 10, 2015 now issued as Chinese Patent No. CN 204972724U, Chinese Application No. 201510581866.0 filed on Sep. 14, 2015, and Chinese Patent Application No. 201510657060.5 filed on Oct. 12, 2015, the entire contents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

This present disclosure relates to a collimator, and more particularly, relates to a multi-leaf collimator and system for driving the multi-leaf collimator.

BACKGROUND

A multi-leaf collimator (MLC) may be used in shaping a radiation beam used in radiosurgery and radiotherapy (RT). Usually, a multi-leaf collimator is driven by one or more motors. The operation of the motors may be affected by the magnetic field generated by a device nearby. Also, current generated by the motors may tangle the magnetic field and thus affect the device nearby. There is a need to overcome such interferences.

SUMMARY

The present disclosure provided herein relates to a collimator. In some embodiments, the collimator may include a motor, a transmission unit having a first end and a second end, and a leaf unit having a leaf. In some embodiments, the first end of the transmission unit may be connected to the motor and the second end of the transmission unit may be connected to the leaf In some embodiments, the collimator may be used in a magnetic field, and the transmission unit may reduce interferences between a motor in the collimator and the magnetic field.

In some embodiments, the collimator may further include a shell configured to contain the motor. In some embodiments, the transmission unit may include a transmission shaft. In some embodiments, the collimator may further include a connection unit configured to connect the transmission unit and the leaf. The leaf may have a groove. The connection unit may have an expansion bump. The expansion bump may match the groove.

In some embodiments, the transmission unit may include a transmission line and an elastic piece. The transmission line may provide the leaf a first force, and the elastic piece may provide the leaf a second force. In some embodiments, the elastic piece may be a spring having a third end and a fourth end. The third end of the spring may be fixed, and the fourth end of the spring may be connected to the leaf. The spring may be in a compressed state. In some embodiments, the leaf may have a thickness in a range from 0.8 mm to 2.2 mm.

In some embodiments, the collimator may further include a conversion unit configured to change a rotational motion of the motor to linear motion. In some embodiments, the transmission unit may be flexible. In some embodiments, the conversion unit may include a gear and a worm. The worm may be connected to the motor. The gear may be driven by the worm. In some embodiments, the gear and the worm may be self-locking.

In some embodiments, the collimator may further include a guiding unit configured to control a movement path of the transmission unit. In some embodiments, the collimator may further include a feedback module configured to detect a movement of the leaf.

In another aspect of the present disclosure, a collimator system is provided. In some embodiments, the collimator system may include a leaf module having a leaf, a driving module having a motor configured to drive the leaf, and a processing module to generate a movement profile of the leaf. The movement profile of the leaf may include a first speed during a first stage, a second speed of the leaf during a second stage, and a third speed of the leaf during a third stage. The first speed may increase with time, the second speed may be constant, and the third speed may decrease at a variable rate with time. In some embodiments, the variable rate may be determined based on a distance between a leaf current location and a leaf target location.

In some embodiments, the collimator system may further include a feedback module configured to detect a movement of the leaf. In some embodiments, the feedback module may include a first feedback unit and a second feedback unit. The first feedback unit may be configured to detect the movement of the leaf, and the second feedback unit may be configured to detect a movement of the motor.

In some embodiments, the processing module may detect a status of the leaf based on the movement of the leaf and the movement of the motor. In some embodiments, the leaf module may include a transmission unit. The transmission unit may be connected to the motor and the leaf In some embodiments, the device may further include a protection module configured to detect whether the motor is running normally.

DETAILED DESCRIPTION

It will be understood that the term “system,” “device,” “apparatus,” “unit,” “module,” “component,” and/or “block” used herein are one method to distinguish different components, elements, parts, section or assembly of different level in ascending order. However, the terms may be exchanged or displaced by other expression if they may achieve the same purpose.

It will be understood that when a device, apparatus, unit, module, component or block is referred to as being “on,” “connected to” or “coupled to” another device, apparatus, unit, module, component or block, it may be directly on, connected or coupled to, or communicate with the other device, apparatus, unit, module, component or block, or an intervening device, apparatus, unit, module, component or block may be present, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

The terminology used herein is for the purposes of describing particular examples and embodiments only, and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “include,” and/or “comprise,” when used in this disclosure, specify the presence of integers, devices, behaviors, stated features, steps, elements, operations, and/or components, but do not exclude the presence or addition of one or more other integers, devices, behaviors, features, steps, elements, operations, components, and/or groups thereof. It will be further understood that the terms “construction” and “reconstruction,” when used in this disclosure, may represent a similar process in which an image may be transformed from data.

FIG. 1is a diagram of a radiation therapy platform100according to some embodiments of the present disclosure. It should be noted that the radiation therapy platform100described below is merely provided for illustration purposes, and not intended to limit the scope of the present disclosure. The collimator system may find its applications in different fields, for example, medicine, or industry. For example, the system may be used in Radiotherapy (RT) and Magnetic Resonance-Radiotherapy (MR-RT). As illustrated inFIG. 1, the radiation therapy platform100may include a collimator system110, a database120, a network130, an external device140, and a radiation generating device, such as a linear accelerator (not shown in the figure).

The collimator system110may provide conformal shaping of beams by changing the configuration of a leaf of the collimator system110. For instance, a leaf may be moved in or out of the path of the beams in order to block the beams or allow it to pass through. In some embodiments, the collimator system110may include a plurality of leaves. In some embodiments, the plurality of leaves may be independently moved. Merely by way of example, the collimator system110may allow the shaping of one or more linear accelerator (LINAC) beams to match the border of a target tumor for conformal radiotherapy. In some embodiments, the collimator system110may create various intensity modulated radiation therapy distributions. In some embodiments, the collimator system110may include leaf driving system. The leaf driving system may drive the leaves.

The database120may store data relating to the radiation therapy platform100. In some embodiments, the data may include an analog signal and/or a digital signal. Merely by way of example, the database120may include a memory. The memory may be a main memory or an assistant memory. The memory may include a Random Access Memory (RAM), a Read Only Memory (ROM), a Complementary Metal Oxide Semiconductor Memory (CMOS), a magnetic surface memory, a Hard Disk Drive (HDD), a floppy disk, a magnetic tape, a disc (CD-ROM, DVD-ROM, etc.), a USB Flash Drive (UFD), or the like, or any combination thereof. Access to the database120may be controlled or gated. A user may need an access privilege to access the database120. Different users may have different access privileges to different data stored in the database120. For instance, a first user may only read a portion of the data stored in the database120, a second user may read and revise a portion of the data stored in the database120, a third user may read all data stored in the database120, a fourth user may read and revise all data stored in the database120, and a fifth user has no access privilege and therefore is unable to read or revise any data stored in the database120. Merely by way of example, the database120may be implemented on a cloud platform. The cloud platform may be a cloud computing platform or a cloud storing platform. The type of the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an inter-cloud, a multi-cloud, or the like, or any combination thereof.

The network130may connect one or more components of the radiation therapy platform100with each other, or with an external device (e.g., an external storage device, an external information source, or the like, or a combination thereof). The network130may be a single network or a combination of different networks. Merely by way of example, the network130may be a tele communications network, a Local Area Network (LAN), a Wireless Local Area Network (WLAN), a Metropolitan Area Network (MAN), a Wide Area Network (WAN), a Bluetooth, a ZigBee, a Near Field Communication (NFC), a public network, a private network, a proprietary network, a Public Telephone Switched Network (PSTN), the Internet, a wireless network, a virtual network, or the like, or any combination thereof.

The external device140may be configured to input or receive data to and/or from a user, the network130, the database120, the collimator system110, or the like, or any combination thereof. In some embodiments, the external device140may include a user input, a controller, a processor, etc. For example, the user input may be a keyboard input, a mouse input, a touch screen input, a handwritten input, an image input, a voice input, an electromagnetic wave input, or the like, or any combination thereof. The controller may be configured to control the collimator system110, the database120, or the network130. The processor may be configured to process data acquired in the external device140. In some embodiments, the collimator system110and the external device140may be integrated as one device. Merely by way of example, the external device140may be a computer, a laptop, a Personal Digital Assistant (PDA), a mobile phone, a tablet computer, a portable device, or the like, or any combination thereof.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, a radiation therapy platform100may include several databases when the collimator system110includes several collimators and several processors. As another example, the collimator system110may be divided into two independent devices. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 2-A illustrates the architecture of a computing device which can be used to realize a specialized system implementing the present teaching. Such a specialized system incorporating the present teaching has a functional block diagram illustration of a hardware platform which includes user interface elements. The computer may be a general purpose computer or a special purpose computer. Both can be used to implement a specialized system for the present teaching. This computer210may be used to implement any component of generating and providing signals as described herein. For example, the processing module221as illustrated inFIG. 2-B, etc., may be implemented on a computer such as computer210, via its hardware, software program, firmware, or a combination thereof. Although only one such computer is shown, for convenience, the computer functions relating to generating and providing signals as described herein may be implemented in a distributed fashion on a number of similar platforms, to distribute the processing load.

The computer210, for example, includes COM ports215connected to and from a network connected thereto to facilitate data communications. The computer210also includes a central processing unit (CPU)212, in the form of one or more processors, for executing program instructions. The exemplary computer platform includes an internal communication bus211, program storage and data storage of different forms, e.g., disk217, read only memory (ROM)213, or random access memory (RAM)214, for various data files to be processed and/or communicated by the computer, as well as possibly program instructions to be executed by the CPU. The computer210also includes an I/O component216, supporting input/output flows between the computer and other components therein such as user interface elements218. The computer210may also receive programming and data via network communications.

Those skilled in the art will recognize that the present teachings are amenable to a variety of modifications and/or enhancements. For example, although the implementation of various components described above may be embodied in a hardware device, it may also be implemented as a software only solution—e.g., an installation on an existing server. In addition, controlling the movement of a leaf including generating and providing signals as disclosed herein may be implemented as a firmware, firmware/software combination, firmware/hardware combination, or a hardware/firmware/software combination.

While the foregoing has described what are considered to constitute the present teachings and/or other examples, it is understood that various modifications may be made thereto and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

FIG. 2-B is a block diagram illustrating the collimator system110according to some embodiments of the present disclosure. As illustrated inFIG. 2-B, the collimator system110may include a processing module221, a driving module222, a feedback module223, and a leaf module225. In some embodiments, the collimator system110may further include a protection module224.

The processing module221may control the movement of a leaf according to a leaf movement profile. The leaf movement profile may include the speed and/or the time of the leaf movement. In some embodiments, the leaf movement profile may be a movement profile of the motor. In some embodiments, the processing module221may determine the leaf movement profile according to parameters including, for example, leaf location information, and time associated with the leaf location information. In some embodiments, the leaf location information may include leaf zero location, leaf initial location, leaf current location, leaf target location, or the like, or a combination thereof. The leaf zero location may be a fixed or predetermined location of a leaf when the collimator system110is initialized. In some embodiments, the leaf initial location may be set as leaf zero location. The leaf target location may be determined based on a desired conformal shaping radiation. In some embodiments, information regarding a desired conformal shaping radiation information may be provided by a user by way of, for example, manual input. In some embodiment, information regarding desired conformal shaping radiation may be provided by detection equipment. Detection equipment may include, for example, a digital subtraction angiography (DSA) system, a magnetic resonance imaging (MM) system, a magnetic resonance angiography (MRA) system, a computed tomography (CT) system, a computed tomography angiography (CTA) system, an ultrasound scanning (US) system, a positron emission tomography (PET) system, a single-photon emission computerized tomography (SPECT) system, a CT-MR system, a CT-PET system, a CT-SPECT system, a DSA-MR system, a PET-MR system, a PET-US system, a SPECT-US system, a TMS (transcranial magnetic stimulation)-MR system, a US-CT system, a US-MR system, an X-ray-CT system, an X-ray-MR system, an X-ray-portal system, an X-ray-US system, a Video-CT system, a Video-US system, or the like, or any combination thereof.

In some embodiments, the processing module221may determine the leaf current location of the leaf according to the leaf initial location and leaf displacement. The leaf displacement, as used herein, may refer to a distance from the leaf initial location to the leaf current location. In some embodiments, the leaf displacement may be acquired by the feedback module223. In some embodiments, the processing module221may generate a driving signal and/or a warning signal to achieve the leaf movement profile. In some embodiments, the driving signal may include a Pulse Width Modulation (PWM) signal, a start signal, a stop signal, or the like, or any combination thereof. In some embodiments, the PWM signal may control the leaf movement. In some embodiments, the start/stop signal may start/stop a motor in the driving module222. In some embodiments, the warning signal may be used to signal a status of the collimator system110. For example, a warning signal may be generated by the process module221when the motor in the driving module222fails. Details regarding the processing module221will be further explained in connection withFIG. 3andFIG. 4.

The driving module222may control the movement of a leaf based on a signal from the processing module221. In some embodiments, the driving module222may control the movement of the leaf movement by driving the motor operationally connected to the leaf. Details regarding the driving module222will be further explained in connection withFIG. 5andFIG. 6.

The feedback module223may determine the leaf displacement. In some embodiments, the feedback module223may determine whether the leaf movement is normal according to the leaf displacement. For instance, the leaf movement may be considered abnormal if the leaf moves out of an acceptable range, beyond a target location, etc. The feedback module223may transmit the leaf displacement information to the processing module221. In some embodiments, the feedback module223may be placed on the driving module222and/or the leaf module225. Details regarding the feedback module223will be further explained in connection withFIG. 7-A andFIG. 7-B.

The protection module224may monitor the working condition of the motor with reference to a monitor signal. In some embodiments, the working conditions may include the operation status, the aging of the motor, or the like, or a combination thereof. In some embodiments, the monitor signal may include a motor current threshold, a motor voltage threshold, or the like, or the combination thereof. Details regarding the protection module224will be further explained in connection withFIG. 8.

The leaf module225may conformally shape beams from an emitter. In some embodiments, the emitter may be a cobalt-60 therapy instrument, an X knife, a y knife, a medical linear accelerator, and a proton accelerator, etc. In some embodiments, the leaf module225may include a collimator, for example, a multi-leaf collimator. Details regarding the leaf module225will be further explained in connection withFIG. 9.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the collimator system110may further include a storage module that may store signals and the leaf location information, etc. As another example, whether the movement of the leaf is normal may be performed by the processing module221. As a further example, the processing module221, the driving module222, the feedback module223, and the protection module224may be implemented in the leaf module225. As still a further example, the protection module224may be unnecessary and removed. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 3is a block diagram of the processing module221according to some embodiments of the present disclosure. The processing module221may include an I/O unit310, a control unit320, and a location information unit330. In some embodiments, the processing module221may the computer210.

The I/O unit310may acquire and transmit a signal. In some embodiments, the I/O unit310may be the I/O component216. In some embodiments, the I/O unit310may acquire a leaf target location. In some embodiments, the leaf target location may be provided by a user, or retrieved from a master computer. The master computer may be a computer which may output control instructions to the collimator system110. In some embodiments, the leaf target location may be determined according to a treatment region acquired by the I/O unit310. In some embodiments, the I/O unit310may acquire information regarding a leaf displacement from the feedback module223. In some embodiments, the I/O unit310may acquire a monitor signal from the protection module224. In some embodiments, the I/O unit310may transmit a warning signal to the user. In some embodiments, the I/O unit310may transmit a driving signal to the driving module222.

The control unit320may determine the leaf movement profile. In some embodiments, the control unit320may be COM ports215. In some embodiments, the control unit320may determine the leaf movement profile according to the leaf location information and leaf location offset acquired from the location information unit330. The leaf location offset as used herein may be a difference between the leaf target location and the leaf current location. Details regarding the leaf location offset will be further explained below.

In some embodiments, the leaf movement profile may include three stages in a round of operation. A round of operation, as used herein, may be an operation for a leaf to move from a location (e.g., an initial position, etc.) to the leaf target location. For the purposes of illustration, the three stages may be marked as a first stage, a second stage, and a third stage, respectively; the time for each stage may be marked as a first time period, a second time period, and a third time period, respectively. In some embodiments, the time periods of the three stages may be set according to factors including, for example, the leaf target location, the distance the leaf needs to travel to reach the leaf target location, or the like, or a combination thereof. For example, the third time period may be set to be a percentage of the time for a round of operation. In some embodiments, the percentage of the third time period in the round of operation may be from 10% to 30%, such as, 5%, 10%, 15%, 20%, 25%, etc. In some embodiments, the leaf speed may increase in the first stage, constant in the second stage, and decrease in the third stage. In some embodiments, the leaf speed may decrease at a constant rate (or slope) or at a variable rate (or slope). Details regarding the leaf location offset will be further explained in connection withFIG. 4AandFIG. 4B.

In some embodiments, the control unit320may generate and/or transmit PWM signals to the driving module222. Different PWM signals may have different duty cycles. As used herein, a duty cycle may be the percentage of a period in which a PWM signal is active or the power is on. PWM signals with different duty cycles may control the output of the motor in the driving module222. In some embodiments, the output of the motor may relate to the leaf speed. For instance, different output of the motor may be associated with different leaf speeds.

The location information unit330may calculate the leaf location offset. In some embodiments, the leaf location offset may be described as below:
E=SP−Senc,  (1)
where E may denote the leaf location offset, SPmay denote the leaf target location, and Sencmay denote the leaf current location.

In some embodiments, the leaf location offset E may be compensated by a correction factor. In some embodiments, the correction factor may compensate, at least partially, for the leaf location offset relating to the mechanical inertia. The compensated leaf location offset Emmay be described as below:
Em=SP−Senc−Vt*Tm,  (2)
where Emmay denote the modified leaf location offset, SPmay denote the leaf target location, Sencmay denote the leaf current location, Vt*Tmmay denote the correction factor, Vtmay denote the real-time speed of the motor, and Tmmay denote the electrical and mechanical time constant of the motor.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the processing module221may further include a storage unit that may store signals and the leaf location information, etc. As another example, the control unit320and the location information unit330may be integrated into one unit. As a further example, the control unit320may determine whether the movement of the leaf is normal according to the leaf current location. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 4AandFIG. 4Billustrate two exemplary leaf movement profiles according to some embodiments of the present disclosure. It should be noted that the leaf initial location in the figures may be the leaf zero location. Then the leaf current location is the leaf displacement. As shown in each ofFIG. 4AandFIG. 4B, the vertical ordinate is the PWM duty cycle and the leaf speed, and the horizontal ordinate is the leaf current location S which is equivalent of the leaf displacement. In some embodiments, the leaf initial location may be different from the leaf zero location. The first stage and the second stage corresponds to an initial PWM duty cycle. The initial PWM duty cycle may be set according to the leaf target location. In some embodiments, the initial PWM duty cycle may be 80% or 90%.

InFIG. 4AandFIG. 4B, the leaf speed may increase in the first stage until the leaf speed reaches Vmax, the leaf speed remains constant at Vmaxin the second stage, and the leaf speed may decrease in the third stage until the leaf speed reaches 0. The leaf may reach the leaf target location at the end of the third stage. Vmax, as used herein, may be the leaf maximum speed in a round of operation. Vmaxmay be proportional to the initial PWM duty cycle. In some embodiments, the Vmaxmay be set according to the leaf target location. In some embodiments, the Vmaxmay be the rated speed of the motor in the driving module222. In some embodiments, the Vmaxmay be obtained through average speed of the leaf in a control period. The control period may relate to the control of the motor. In some embodiments, the average speed of the leaf may be calculated by the distance difference between the leaf location at the start point and the leaf location at the end point the leaf travels within a control period divided by the duration of the control period. As shown inFIG. 4AandFIG. 4B, the leaf current location at the end point of the second stage may be marked as k*Sp, where k may denote a constant which is less than one, and Sp may denote the leaf target location. In some embodiments, k may be 0.8, or 0.85, or 0.9, etc.

InFIG. 4A, the PWM duty cycle may start to decrease at k*SPwith a constant slope. The leaf speed may start to decrease correspondingly at k*SP. In some embodiments, the constant slope may be determined by Vmaxdivided by T, where T is an electrical and mechanical time constant of the motor. T may also be referred to as Tmas in Equation (5).

InFIG. 4B, the PWM duty cycle may start to decrease at k*SPwith a variable slope. The leaf speed may start to decrease correspondingly at k*SP. In some embodiments, the variable slope may be determined based on, for example, the remaining distance the leaf needs to move to reach the leaf target location SPand the time available for the movement. The remaining distance, as used herein, may be the distance between the leaf current location S and the leaf target location SP. In some embodiments, the variable slope may decrease as the remaining distance decreases. The dynamic slope of the PWM duty cycle may be described as below:
P(SP)=b*(S−SP)2,  (3)
where P(SP) may denote the variable slope of the PWM duty cycle, S may denote the leaf current location, SPmay denote the leaf target location, and b is described as below:
b=(1−k)2*s/P,(4)
where k may denote a constant that is less than one, S may denote the leaf current location, P may denote the PWM duty cycle when the motor in the driving module222is running with the rated speed.

In some embodiments, the dynamic slope of the PWM duty cycle P(SP) may be modified according to Equation (2), which may be described as below:
P(SP)=b*(S−SP−Vt*Tm)2,  (5)
where P(SP) may denote the dynamic slope of the PWM duty cycle, b is described as Equation (4), S may denote the leaf current location, SPmay denote the leaf target location, Vtmay denote the real-time speed of the motor, and Tmmay denote the electrical and mechanical time constant of the motor.

FIG. 5is a block diagram of the driving module222according to some embodiments of the present disclosure. The driving module222may include a signal isolation circuit510, a control logic unit520, a driving signal amplification unit530, a charge pump circuit540, and a motor550.

The signal isolation circuit510may reduce influence of noise on the control unit320. In some embodiments, the signal isolation circuit510may be a photoelectric isolation circuit. In some embodiments, the signal isolation circuit510may acquire a driving signal from the processing module221. The driving signal may be a power signal. The control logic unit520may conduct a logic operation based on the driving signal. In some embodiments, the logic relationship operation may be an AND operation between an enable signal and the driving signal. The driving signal amplification unit530may amplify the driving signal. In some embodiments, the amplified driving signal may drive the motor550. In some embodiments, the driving signal amplification unit530may include an H bridge driver with one or more N field effect transistors. The gate voltage may be greater than the drain voltage when an N field effect transistors start. The charge pump circuit540may increase the gate voltage so that the gate voltage may be greater than the drain voltage. The motor550may drive the leaf in the leaf module225. Exemplary motors may include a rotating motor, a linear motor, etc. As used herein, the linear motor may convert electric energy to mechanical energy in the form of a linear movement.

FIG. 6is an exemplary circuit of the charge pump circuit540according to some embodiments of the present disclosure. As shown inFIG. 6, Vin may be a square-wave signal. Vin may be amplified though Volt Current Condenser (VCC). Vout may be the sum of Vin and VCC. Vout may be the amplified square-wave signal.

FIG. 7-A is a block diagram of the feedback module223according to some embodiments of the present disclosure. The feedback module223may include a first feedback unit710, a second feedback unit720, a comparator730, and a decision unit740.

The first feedback unit710may detect the leaf displacement. For the purposes of illustration, the leaf displacement detected by the first feedback unit710may be marked as the first leaf displacement A. In some embodiments, the first feedback unit710may be placed on the motor550in the driving module222, or the guiding unit930in the leaf module225, or the leaf unit940in the leaf module225, or a combination thereof. Merely by way of example, the first feedback unit710may be placed on the guiding unit930in the leaf module225and the leaf unit940in the leaf module225.

In some embodiments, the first feedback unit710may be a linear encoder displacement transducer including a grating ruler and a corresponding grating ruler reading head. The grating ruler may be placed on the top side of the leaf in the leaf unit940. The corresponding grating ruler reading head may be placed on the interior of the guiding box in the leaf unit940. The interior may be opposite, with respect to the top side of the leaf. The top side of the leaf, as used herein, may be the top side of the leaf along the horizontal movement of the leaf. In some embodiments, the location of the corresponding grating ruler reading head may be opposite, with respect to the location of the grating ruler. In some embodiments, the grating ruler displacement transducer may detect the first leaf displacement according to the movement of the grating ruler relative to the grating ruler reading head.

In some embodiments, the first feedback unit710may be a magnetic encoder displacement transducer including magnetic elements and corresponding magnetic element reading pieces. In some embodiments, the magnetic element may be a bar magnet, and the magnetic element reading piece may be a hall sensor. The magnetic elements may be placed on the top side of the leaf in the leaf unit940. The corresponding magnetic element reading pieces may be placed on the interior of guiding box in the leaf unit940. The interior may be opposite, with respect to the top side of the leaf. The top side of the leaf, as used herein, may be the top side of the leaf along the horizontal movement of the leaf. In some embodiments, the location of the magnetic element reading pieces may be opposite, with respect to the location of the magnetic elements. In some embodiments, the magnetic encoder displacement transducer may detect the first leaf displacement according to the movement of the magnetic elements relative to the corresponding magnetic element reading pieces. As an example, the corresponding magnetic element reading pieces may detect the variation of the magnetic field and output a pulse signal; the first leaf displacement may be calculated based on the pulse signal.

In some embodiments, the first feedback unit710may be an encoder or a potentiometer. The encoder/potentiometer may be placed on the motor550, such as a shaft of the motor550, the guiding wheel in the guiding unit930, the reeling wheel in the guiding unit930, etc. In some embodiments, the encoder and/or potentiometer may detect the first leaf displacement according to number of rounds the motor550, or the guiding wheel, or the reeling wheel rotates.

The second feedback unit720may detect the leaf displacement. For the purposes of illustration, the leaf displacement detected by the second feedback unit720may be marked as the second leaf displacement B. In some embodiments, the second feedback unit720may include the same displacement transducers as the first feedback unit710. In some embodiments, the second feedback unit720may include different displacement transducers than the first feedback unit710. In some embodiments, the second feedback unit720may be placed at the same or similar location as the first feedback unit710. In some embodiments, the second feedback unit720may be placed at a different location than the first feedback unit710.

The comparator730may compare the first leaf displacement A and the second leaf displacement B. In some embodiments, the comparator730may determine the difference between A and B, a multiple of |A-B| and A, a multiple of |A-B| and B, etc. For the purposes of illustration, the difference between A and B may be marked as C, the multiple of |A-B| and A may be marked as D, and the multiple of |A-B| and B may be marked as E. In some embodiments, the comparator730may further compare C, and/or D, and/or E with a threshold, respectively. The comparator730may transmit the comparison result to the decision unit740.

The decision unit740may determine whether the movement of the leaf is normal according to the comparison result acquired from the comparator730. As an example, the comparison result may be that D is less than the threshold, or that D is not less than the threshold. In some embodiments, the threshold may be 5%. When the comparison result is that D is less than 5%, the decision unit740may determine that the movement of the leaf is normal; when the comparison result is that D is not less than 5%, the decision unit740may determine that the movement of the leaf is abnormal. The decision unit740may transmit the determination result to the processing module221.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the feedback module223may further include a storage unit configured to store the leaf displacement, the comparison result, the determination result, etc. As another example, the comparator730and the decision unit740may be unnecessary and removed from the control unit320. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 7-B is an exemplary diagram of the comparator730and the decision unit740according to some embodiments of the present disclosure. Leaf displacement acquired by the first feedback unit710and the second feedback unit720may be provided to the comparator730. The comparator730may compare the difference between the leaf displacement measured by the first feedback unit710and the leaf displacement measured by the second feedback unit720. The decision unit740may determine whether the movement of the leaf is normal according to the comparison result acquired from the comparator730. Details regarding the comparator730and the decision unit740may be found elsewhere in the present disclosure, for example, in the description ofFIG. 7-A.

FIG. 8is a block diagram of the protection module224according to some embodiments of the present disclosure. The protection module224may include an inductive resistor810, an isolation amplifier820, an operational amplifier830, an A/D converter840, and a CPU850.

The inductive resistor810may be connected in series with the motor550. The protection module224may acquire a partial voltage of the inductive resistor810through a detecting current of the inductive resistor810. To allow the motor550to have a higher partial voltage, the resistance of the inductive resistor810may be less than 2 ohm, such as 1 ohm. In some embodiments, the partial voltage of the inductive resistor810may be less than 1 volt. The partial voltage of the inductive resistor810may be amplified by the isolation amplifier820and/or the operational amplifier830. The amplified partial voltage of the inductive resistor810may be an analogue signal. The analogue signal may be converted to a digital signal by the A/D converter840. The digital signal may be transmitted to the CPU850. In some embodiments, the CPU850may determine whether the operation of the motor550is normal according to the digital signal. As an example, the CPU850may determine that the operation of the motor550is abnormal when the digital signal exceeds a threshold. The CPU850may transmit the result to the control unit320.

In some embodiments, the CPU850may assess the degree of aging of the motor550. In some embodiments, the CPU850may assess the degree of aging of the motor550according to working current of the motor550. In some embodiments, the working current of the motor550may be equivalent to the current of the inductive resistor810. In some embodiments, the working current of the motor550may increase as the degree of aging increases, when the motor550drives a same load. In some embodiments, the CPU850may determine the multiple of a working current and an initial current of the motor550. The initial current of the motor550, as used herein, may be the current of the motor550obtained at an early period of the motor550driving a same load. The early period, as used herein, may be a period that the motor is new and is not used before. In some embodiments, the CPU850may further compare the multiple of a working current and an initial current of the motor550with a threshold. In some embodiments, the threshold may be determined according to an aging curve of the motor550. In some embodiments, the threshold may be 1.1, 1.2, etc. The CPU850may transmit the comparison result to the control unit320. The control unit320may generate a warning signal according to the comparison result.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the protection module224may further include another inductive resistor. As another example, the CPU850may be unnecessary and removed from the control unit320. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 9is a block diagram of the leaf module225according to some embodiments of the present disclosure. The leaf module225may include a conversion unit910, a transmission unit920, a guiding unit930, a leaf unit940, a connection unit950, and a shell unit960.

The conversion unit910may convert the movement form of the motor550. In some embodiments, the conversion unit910may convert a rotation motion of the motor550to a linear motion. In some embodiments, the conversion unit910may be the conversion piece described in connection withFIG. 15. Details regarding the conversion piece may be found elsewhere in the present disclosure. See, for example, the description ofFIG. 15. In some embodiments, the conversion unit910may convert the direction of the movement of the motor550, for example, convert a motion in the horizontal direction to a motion in the vertical direction. In some embodiments, the conversion unit910may be the conversion piece described inFIG. 24. Details regarding the conversion piece may be found elsewhere in the present disclosure. See, for example, the description ofFIG. 24.

In some embodiments, the conversion unit910may be connected to the transmission unit920directly or indirectly and may drive the transmission unit920. In some embodiments, the conversion unit910may be connected to the transmission unit920indirectly through the connection unit950.

The transmission unit920may transmit the movement between different units in the leaf module225. In some embodiments, the transmission unit920may transmit the movement between the conversion unit910and the leaf unit940. In some embodiments, the transmission unit920may enlarge the distance, and/or change the relative location between the conversion unit910and the leaf unit940.

In some embodiments, the transmission unit920may include a flexible transmission shaft. The transmission shaft may be and incompressible. In some embodiments, the transmission shaft may be made from a non-magnetic material. Merely by way of example, the non-magnetic material may be stainless steel, an alloy (e.g., aluminum ally, etc.), rubber, plastics, or the like, or the combination thereof. In some embodiments, the transmission unit920may be the transmission shaft illustrated inFIG. 14and the description thereof. In some embodiments, the transmission unit920may be the transmission shaft illustrated inFIG. 22-B and the description thereof.

In some embodiments, the transmission unit920may include a transmission line and an elastic piece. In some embodiments, the transmission line may be a steel wire. In some embodiments, the transmission unit920may be the transmission line and the elastic piece illustrated inFIG. 23and the description thereof. Details regarding the transmission line and the elastic piece may be found elsewhere in the present disclosure. See, for example, the description ofFIG. 23.

The guiding unit930may control the moving path of the transmission unit. In some embodiments, the guiding unit930may be a sleeve having a hollow structure. In some embodiments, the shape of the sleeve may be linear or curved, such as an L shape as shown inFIG. 14-C andFIG. 14-D. In some embodiments, the guiding unit930may be a guiding box. In some embodiments, the sleeve may be placed in the guiding box. In some embodiments, the shape of the guiding box may be the same as or similar to the shape of the sleeve. In some embodiments, the shape of the guiding box may be different from the shape of the sleeve. In some embodiments, the shape of the guiding box may be linear or curved, such as an L shape as shown inFIG. 14-A. In some embodiments, the guiding unit930may include a sleeve as illustrated inFIG. 14-C andFIG. 14-D and the description thereof. In some embodiments, the guiding unit930may include a guiding box as illustrated inFIG. 14-A andFIG. 14-B and the description thereof. In some embodiments, the guiding unit930may include a sleeve as illustrated inFIG. 20-A and the description thereof. In some embodiments, the guiding unit930may include a guiding wheel and a reeling wheel as illustrated inFIG. 23and the description thereof.

The leaf unit940may form a conformal shaping. In some embodiments, the leaf unit940may include a plurality of leaves and a leaf guiding rail. The leaves may move independently in and out of the path of beams (e.g., particle beams, etc.) to provide a conformal shaping. The thickness of the leaves may influence the conformal shaping. In some embodiments, the thickness of a leaf may be from 0.8 mm to 2.2 mm, from 0.8 to 1.6 mm, from 0.8 to 1.3 mm, from 1.0 to 1.8 mm, from 1.0 to 1.5 mm. In some embodiments, a leaf may be made of a high atomic numbered material, for example, tungsten. The leaf guiding rail may limit the moving path of a leaf. In some embodiments, the leaf guiding rail may include a leaf guide groove. A leaf may be placed in the leaf guiding rail. The leaf may undergo a linear motion within the leaf guiding rail. In some embodiments, descriptions of a leaf of the leaf unit940may be found elsewhere in the present disclosure. See, for example,FIG. 14,FIG. 20, andFIG. 23, and the description thereof.

The connection unit950may connect different units in the leaf module225. In some embodiments, the connection unit950may connect the conversion unit910and the transmission unit920. In some embodiments, the connection unit950may connect the transmission unit920and the guiding unit930. In some embodiments, the connection unit950may connect the guiding unit930and the leaf unit940. In some embodiments, the connection unit950may connect the transmission unit920and the leaf unit940. In some embodiments, the connection may be in the form of a removal connection, a non-removal connection, or the like, or a combination thereof. In some embodiments, the connection unit950may include a hard straight bar. In some embodiments, the connection unit950may include a connection piece as illustrated inFIG. 18and the description thereof.

The motor550may be contained in the shell unit960. In some embodiments, the shell unit960may shield the motor550from the magnetic field. In some embodiments, the shell unit960may be made from stainless steel, aluminum, or the like, or an alloy thereof.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the conversion unit910may be unnecessary and removed. As another example, the leaf module225may further have a motor and a support for the motor. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 10illustrates an exemplary process1000for the collimator system110according to some embodiments of the present disclosure. In step1001, the target location of the leaf may be acquired. In some embodiments, the target location of the leaf may be acquired through the I/O unit310. In some embodiments, the target location of the leaf may be provided by a user, from a master computer, etc. The master computer may provide control instructions to the collimator system110. In some embodiments, the target location of the leaf may be determined based on a treatment region of a subject (e.g., a patient, etc.). In some embodiments, the leaf target location may be set according to a desired conformal shaping.

In step1002, the leaf movement profile may be determined based on, e.g., the initial location, a current location, the target location of the leaf, the time associated with a location of the leaf, the time available for a leaf to reach its target location, or the like, or a combination thereof. In some embodiments, the leaf movement profile may be determined by the control unit320. In some embodiments, the leaf movement profile may include three stages, referred to as a first stage, a second stage, and a third stage. In some embodiments, the leaf speed may increase in the first stage, be constant in the second stage, and decrease in the third stage. In some embodiments, the leaf speed may decrease at a constant rate (or slope) or at a variable rate (or slope).

In step1003, a leaf may be driven according to the leaf movement profile. In some embodiments, the leaf may be driven based on a driving signal generated by the control unit320. In some embodiments, the step1003may be conducted in the driving module222. In step1004, the current location of the leaf may be determined based on the leaf initial location and the leaf displacement. In some embodiments, the determination of the current location of the leaf may be performed by the control unit320. In some embodiments, the current location of the leaf may be used to determine or update the leaf movement profile.

Merely by way of example, an initial movement profile of a leaf, including a first stage, a second stage, and a third stage, may be provided. The third stage of the initial movement profile may be updated in real time or periodically based on the measured leaf current locations and the time available for the leaf to reach its target location. In some embodiments, the first stage and/or the second stage of the movement profile may be updated such that the leaf reaches its target location at a desired time.

It should be noted that the above description is merely provided for the purposes of illustration, and not intended to limit the scope of the present disclosure. For persons having ordinary skills in the art, multiple variations and modifications may be made under the teachings of the present disclosure. For example, the process1000may further include determining whether the movement of the leaf is normal. As another example, the process1000may further include stopping the movement of the leaf when an abnormality occurs is identified. However, those variations and modifications do not depart from the scope of the present disclosure.

FIG. 11is an example of the collimator system110according to some embodiments of the present disclosure. As shown inFIG. 11, the collimator system1100may include a control unit1110, a location information unit1120, a driving module1130, a leaf module1140, and a feedback module1150.

The control unit1110may acquire the leaf target location. The leaf target location may be determined based on a desired conformal shaping. The control unit1110may acquire the leaf initial location that may be set as the leaf zero location. The control unit1110may determine the leaf current location according to the leaf initial location and the leaf displacement acquired by, for example, the feedback module1150. The control unit1110may acquire the leaf location offset from the location information unit1120. The leaf location offset may be determined based on the leaf current location and the leaf target location. The leaf location offset may also be determined based on the correction factor Vt*Tmas described in connection withFIG. 3. The control unit1110may determine the leaf movement profile based on the leaf initial location, the leaf current location, the leaf target location, the leaf location offset, relevant time information, or the like, or a combination thereof. The control unit1110may generate a driving signal. The driving module1130may drive, based on the driving signal, the motor in the driving module1130. The motor may drive the leaf in the leaf module1140to move following the movement profile. The leaf may reach the leaf target location and facilitate the formation of the desired conformal shaping.

FIG. 12is an example of the collimator system110according to some embodiments of the present disclosure. As shown inFIG. 12, the collimator system1200may include a control unit1110, a location information unit1120, a driving module1130, a leaf module1140, and a feedback module1210. The feedback module1210may include a first feedback unit1211and a second feedback unit1212.

The first feedback unit1211may detect the movement of the leaf in the leaf module1140. The first feedback unit1211may determine the leaf displacement according to the movement of the leaf in the leaf module1140. The second feedback unit1212may detect the motion of the motor in the driving module1130. The second feedback unit1212may determine the leaf displacement based on the motion of the motor.

In some embodiments, the leaf displacement determined by the first feedback unit1211and the second feedback unit1212may be equivalent. The control unit1110may determine the leaf movement profile as illustrated inFIG. 11and the description thereof. “Equivalent,” as used herein, may indicate that the leaf displacement determined by the first feedback unit1211and the leaf displacement determined by the second feedback unit1212are exactly the same, or that the difference between the leaf displacement determined by the first feedback unit1211and the leaf displacement determined by the second feedback unit1212is less than a threshold. See, for example,FIG. 7and the description thereof.

In some embodiments, the leaf displacement determined by the first feedback unit1211and the leaf displacement determined by the second feedback unit1212may be inequivalent. The control unit1110may generate a driving signal. The driving signal may be transmitted to the driving module1130. The driving signal may include a stop signal. The stop signal may stop the motor in the driving module1130such that the leaf in the leaf module1140may stop.

FIG. 13is an example of the collimator system110according to some embodiments of the present disclosure. As shown inFIG. 13, the collimator system1300may include a control unit1110, a location information unit1120, a driving module1130, a leaf module1140, a feedback module1310, and a protection module1320.

In some embodiments, the feedback module1310maybe a feedback module1150as illustrated inFIG. 11and the description thereof. In some embodiments, the feedback module1310may include a first feedback unit and a second feedback unit, similar to the feedback module1210illustrated inFIG. 12and the description thereof.

The protection module1320may detect the current of the motor in the driving module1130. In some embodiments, the protection module1320may determine whether the operation of the motor in the driving module1130is normal based on the detected current of the motor. In some embodiments, if the detected current of the motor exceeds a threshold, the operation of the motor may be deemed abnormal. See, for example,FIG. 8and the description thereof. In some embodiments, the protection module1320may assess the degree of aging of the motor in the driving module1130. The assessment may be based on the detected current of the motor. The protection module1320may assess the difference of the working current and the initial current of the motor, and determine the degree of aging of the motor according to an aging curve of the motor. See, for example,FIG. 8and the description thereof.

When the operation of the motor is abnormal, the control unit1110may generate driving signal and transmit the driving signal to the driving module. The driving signal may be stop signal. The stop signal may stop the motor and the leaf in the leaf module1140may stop. When the degree of aging is more than a threshold, the control unit1110may generate warning signal and transmit the warning signal to operators to take actions. The actions may include changing the motor in the driving module1130.

FIG. 14-A toFIG. 14-D illustrate an exemplary MLC according to some embodiments of the present disclosure.FIG. 14-A illustrates the front view of the MLC.FIG. 14-B illustrates the top view of the MLC.FIG. 14-C andFIG. 14-D illustrate an internal structure of the MLC. As shown inFIG. 14-A toFIG. 14-D, the MLC1400may include a motor1401, a guiding box1402, a connection piece1403, a leaf guiding rail1404, a leaf1405, a conversion piece1406, a transmission shaft1407, and a sleeve1408. The motor1401may be placed on a supporting base (for example,1601inFIG. 16). The sleeve1408may be located within the guiding box1402. The leaf guiding rail1404may include a leaf guiding groove. The leaf guiding groove may limit the moving path of the leaf1405. The transmission shaft1407may connect the motor1401and the leaf1405. The transmission shaft1407may be flexible. The transmission shaft1407may be incompressible. The transmission shaft1407may include a hollow structure. The sleeve1408may include a hollow structure. The guiding box1402, the transmission shaft1407, or the sleeve1408may have an L-shape. Description regarding the connection piece1403may be found elsewhere in the present disclosure. See, for example,FIG. 17and the description thereof. The thickness of the leaf1405may influence the conformal shaping of radiation beams. The thickness of the leaf1405may be from 0.8 mm to 2.2 mm, from 0.8 mm to 1.6 mm, from 0.8 mm to 1.3 mm, from 1.0 mm to 1.8 mm, from 1.0 mm to 1.5 mm, etc. The leaf1405may be made from a material that has properties including, for example, high density, high hardness, proper machinability, or the like, or a combination thereof. The leaf1405may be made of, for example, tungsten, aluminum, magnesium, stainless steel, copper, or the like, or an alloy thereof.

The motor1401may be operationally connected to the conversion piece1406. The conversion piece1406may be operationally connected to the transmission shaft1407. The transmission shaft1407may be operationally connected to the leaf1405via the connection piece1403. The transmission shaft1407may be placed in the hollow structure of the sleeve1408. The sleeve1408may be placed in the guiding box1402in a distributed form. The leaf1405may be placed in the leaf guiding rail1404.

For the purposes of illustration, the motor1401may undergo a clockwise rotation. Via the conversion of the conversion piece1406, the transmission shaft1407may undergo a linear movement toward to the motor1401. Details regarding the conversion piece1406may be found elsewhere in the present disclosure. See, for example,FIG. 15andFIG. 16and the description thereof. The connection piece1403and the leaf1405may undergo a linear movement driven by the transmission shaft1407. The leaf1405may retract to the guiding box1402along the leaf guiding rail1404in the form of a linear movement. The motor1401may undergo an anticlockwise rotation. Via the conversion of the conversion piece1406, the transmission shaft1407may undergo a linear movement away from the motor1401. The connection piece1403and the leaf1405may undergo a linear movement driven by the transmission shaft1407. The leaf1405may stretch out of the guiding box along the leaf guiding rail1404in the form of a linear movement.

FIG. 15illustrate an exemplary structure of the conversion piece1406according to some embodiments of the present disclosure. The conversion piece1406may include a three-stage coupling1501, a bearing1502, a screw1503, and a nut1504. The nut1504may be placed around the screw1503. The nut1504may match the threads of the screw1503. The nut1504may be fixedly connected to the transmission shaft1407. The three-stage coupling1501may include a first coupling, a second coupling, and a third coupling. The first coupling, the second coupling, and the third coupling may be arranged in a coaxial direction along the axis of the three-stage coupling1501. The first coupling may include a first cavity. The third coupling may include a second cavity. The output shaft of the motor1401may be connected to the screw1503through the three-stage coupling1501and the bearing1502. The output shaft of the motor1401may be placed in the first cavity. One end of the screw1503may be placed in the second cavity. The other end of the screw1503may be placed in the hollow structure of the transmission shaft1407. The length of the hollow structure in the transmission shaft1407may be equal to or less than the length of the transmission shaft1407. The aperture of the hollow structure in the transmission shaft1407may be greater than the aperture of the screw1503.

When the motor1401is operating, the rotational motion of the output shaft of the motor1401may be output to the end of the screw1503in the second cavity of the third coupling through the second coupling. Due to the three-stage coupling, the disalignment of the motor1401output shaft and the screw1503may be compensated. The screw1503may undergo a rotational movement. The nut1504may undergo a linear movement along the screw1503. During the linear movement of the nut1504, the screw1503may undergo a movement in the hollow structure of the transmission shaft1407. The hollow structure in the transmission shaft1407may be located at the end of the transmission shaft1407where the end of the transmission shaft1407is connected to the nut1504. The hollow structure may provide room for the movement of the screw1503. The transmission shaft1407connected fixedly with the nut1504may undergo a linear movement. Details regarding the conversion piece1406may be found elsewhere in the present disclosure. See, for example,FIG. 16and the description thereof.

FIG. 16illustrates an exemplary inner structure of the supporting base1601according to some embodiments of the present disclosure. The supporting base1601may include a nut guiding rail1602. The nut guiding rail1602may limit the moving path of the nut1504. When the motor1401is operating, the screw1503may undergo a rotational movement. Due to the limitation of the nut guiding rail1602, the nut1504may undergo a linear movement along the screw1503. Due to the fixed connection between the nut1504and the transmission shaft1407, the transmission shaft1407may undergo a linear movement. The rotational motion of the motor1401may be converted to a linear movement of the transmission shaft1407.

FIG. 17-A toFIG. 17-C illustrate exemplary connections between the leaf1405and the transmission shaft1407according to some embodiments of the present disclosure.FIG. 17-A andFIG. 17-B illustrate clamp connections between the leaf1405and the transmission shaft1407.FIG. 17-C illustrates a bolted connection between the leaf1405and the transmission shaft1407. As shown inFIG. 17-A andFIG. 17-B, one end of the connection piece1403may include an expansion bump1701. The leaf1405may include a groove1702. The expansion bump1701may have a shape of a hemicycle, a trapezoid, etc. The expansion bump1701may match the groove1702. The transmission shaft1407may be operationally connected to the leaf1405via the expansion bump1701and the groove1702. As shown inFIG. 17-C, one end of the connection piece1403may include a bending part. The bending part may have an L-shape. Two bolts1703may be placed on the back side of the leaf1405. The back side of the leaf, as used herein, may be the right side of the leaf1405along the horizontal movement of the leaf1405. The bending part of the connection piece1403may be connected to the leaf1405.

FIG. 18illustrate an exemplary shell of the MLC1400according to some embodiments of the present disclosure. As shown in the figure, the motor1401may be placed on the supporting base. The shell1801may be a hollow cuboid and may cover the motor1401. The shell1801may shield the motor1401from a magnetic field. In some embodiments, the shell1801may be made from stainless steel, aluminum, or the like, or an alloy thereof.

FIG. 19-A toFIG. 19-B illustrate an exemplary MLC according to some embodiments of the present disclosure.FIG. 19-A illustrates the top view of the MLC.FIG. 19-B illustrates a sectional view of the MLC. As shown inFIG. 19-A andFIG. 19-B, the MLC1900may include a driving piece1901, a transmission piece1902, a supporting base1903, a brace1904, a mounting plate1905, a guiding box1906, a first connection piece1907, and a leaf1908. The driving piece1901, the transmission piece1902, and the leaf1908may form a grating unit. The driving piece1901may include a motor and a conversion piece. The motor and the transmission piece1902may be connected through the conversion piece. The conversion piece may convert a rotational movement of the motor to a linear movement of the transmission piece1902. Details regarding the conversion piece may be found elsewhere in the present disclosure. See, for example,FIG. 15andFIG. 16and the description thereof.

The transmission piece1902may include a transmission shaft2107(shown inFIG. 21-A) and a sleeve2101(shown inFIG. 21-A). The transmission shaft2107and the sleeve2101may be flexible. The sleeve2101may bend with different bending radius. The bending radius may be determined based on relative location of magnetic field and the motor and diameter of the transmission shaft2107. The diameter of the transmission shaft2107may be, for example, from 0.5 mm to 1.0 mm. Deformation of the sleeve2101and friction between the transmission shaft2107and the sleeve2101may increase as the bending radius decreases. Gear lubricant may be placed in the sleeve2101to reduce the friction between the transmission shaft2107and the sleeve2101. The gear lubricant may be radiation resistant. The relative location of the motor in the driving piece1901from the leaf1908may be adjusted by adjusting the bending radius. By adjusting the relative location, the interference between the magnetic field and the motor in the driving piece1901may be reduced when the leaf1908is subject to the magnetic field. The sleeve2101may include an extension spring. The transmission shaft2107may move independently in the sleeve2101. The transmission shaft2107and the sleeve2101may be made from a non-magnetic material including, for example, stainless steel, an alloy (e.g., aluminum ally, etc.), rubber, plastics, or the like, or a combination thereof.

The leaf1908may be made from a material that has properties including, for example, high density, high hardness, proper machinability, or the like, or a combination thereof. The leaf1908may be made of, for example, tungsten, aluminum, magnesium, stainless steel, copper, or the like, or an alloy thereof. Thickness of the leaf1908may influence the conformal shaping of radiation beams. The thickness of the leaf1405may be from 0.8 mm to 2.2 mm, from 0.8 mm to 1.6 mm, from 0.8 mm to 1.3 mm, from 1.0 mm to 1.8 mm, from 1.0 mm to 1.5 mm, etc.

As shown in the figures, the leaf1908may be divided into two groups. The two groups may be placed on the opposite sides of the mounting plate1905. At least a part of the driving piece1901may be located on the supporting base1903. The supporting base1903may be held by one end of the brace1904. The other end of the brace1904may be placed on the mounting plate1905. A guiding box1906may be attached to the mounting plate1905. The leaf1908may be placed in the guiding box1906. The guiding box1906may include a leaf guiding groove (not shown in the figures). The leaf guiding groove may be congruous with the leaf1908and limit the moving path of the leaf1908. The leaf1908may undergo a reciprocal movement in the leaf guiding groove. The MLC1900may form a desired conformal shaping according to the shape of a target region (e.g., a treatment region, etc.) through the reciprocal movement of the leaf1908.

The MLC1900may further include a second connection piece (not shown in the figure). The second connection piece may be operationally connect the transmission shaft2107and the leaf1908. The second connection piece may be the connection piece1403as illustrated inFIG. 17-A toFIG. 17-C and the description thereof.

The MLC1900may further include a shell (not shown in the figure). The shell may cover the motor in the driving piece1901and shield the motor from a magnetic field. The shell may be made from stainless steel, aluminum, or the like, or an alloy thereof. The shell1801illustrated inFIG. 18may be used.

FIG. 20illustrates an exemplary construction of the grating unit inFIG. 19-A andFIG. 19-B according to some embodiments of the present disclosure. The driving piece1901may be connected to the transmission piece1902. Details regarding connection between the transmission piece1902and the driving piece1901may be found elsewhere in the present disclosure. See, for example,FIG. 21-A and the description thereof. The driving piece1901and the leaf1908may be connected through the first connection piece1907. Details regarding connection between the transmission piece1902and the leaf1908may be found elsewhere in the present disclosure. See, for example,FIG. 21-B and the description thereof. The leaf1908may be placed in the guiding box1906.

When the motor in the driving piece1901is operating, the rotating motion from the output shaft of the motor may be output to the conversion piece in the driving piece1901. The conversion piece in the driving piece1901may convert the rotational motion from the motor to the linear movement of the transmission shaft2107in the transmission piece1902. The conversion piece in the driving piece1901may be the conversion piece1406in MLC1400. Details regarding the conversion piece in the driving piece1901may be found elsewhere in the present disclosure. See, for example,FIG. 15andFIG. 16and the description thereof. The transmission shaft2107may undergo a linear movement toward to the motor or away from the motor. Correspondingly, the leaf1908may retract to or stretch out of the guiding box1906. By the movement of the leaf1908, a desired conformal shape may be obtained.

FIG. 21-A andFIG. 21-B illustrate an exemplary immobilization regarding the sleeve2101according to some embodiments of the present disclosure.FIG. 21-A illustrates the connection between the sleeve2101and the supporting base1903.FIG. 21-B illustrates the connection between the sleeve2101and the leaf guiding box1906.

As shown inFIG. 21-A, the sleeve2101may be fixed on the supporting base1903through a sleeve fixed piece2102and a nut2106. The sleeve fixed piece2102may have an opening2108. An outside diameter of the opening2108may match the diameter of the sleeve2101. The nut2106may have an opening2109. The outside diameter of the opening2109may match the diameter of the transmission shaft2107. One end of the sleeve2101may be fixed on the supporting base1903through the sleeve fixed piece2102. The sleeve2101may be placed into the opening2108and the sleeve2101may be fixed by inserting a set screw2103. One or more set screws2103may be used. One end of the transmission shaft2107may stretch out of the sleeve2101and placed into the opening2109. The transmission shaft2107may be fixed by inserting a set screw2104. In order to fix the transmission shaft2107more stably, the transmission shaft compressing piece2105may be inserted into the nut2106through an interference fit. The transmission shaft compressing piece2105may be configured with an opening (not shown in the figure) of which outside diameter may match the diameter of the transmission shaft2107. With the transmission shaft2107passing through the opening2109and the opening of the transmission shaft compressing piece2105, the transmission shaft2107may be fixed by the set screw2104. One or more set screw2104may be used.

As shown inFIG. 21-B, the sleeve2101may be fixed on the guiding box1906through the first connection piece1907. The first connection piece1907may be placed behind the leaf1908. The first connection piece1907may be connected to the guiding box1906. The first connection piece1907may have an opening2110. The outside diameter of the opening2110may match the diameter of the sleeve2101. The opening2110may be a threaded opening. The transmission shaft2107may be screwed into the threaded opening to form a fixed connection. The opening2110may be configured along the horizontal movement of the leaf1908. The deformation of the transmission shaft2107may be reduced during the movement of the leaf1908. In order to make the connection between the sleeve2101and the first connection1907more stably, a fastener structure (not shown in the figure) may be included in the first connection piece1907.

The sleeve2101, the transmission shaft2107, and the transmission shaft compressing piece2105may be made from a non-magnetic material. The sleeve2101and the transmission shaft compressing piece2105may be made from stainless steel, copper, or the like, or an alloy thereof. The transmission shaft2107may be made from a non-magnetic material with high hardness, for example, stainless steel, etc. The nut2106may be made from, for example, a radiation resistant resin composite.

FIG. 22-A toFIG. 22-C illustrate an exemplary MLC according to some embodiments of the present disclosure.FIG. 22-A illustrates the configuration of the MLC2200. As shown inFIG. 22-A, the MLC may include a driving unit2201and a leaf unit2202. The leaf unit2202may be driven by the driving unit2201. The leaf unit2202may facilitate the formation of a desired conformal shape of radiation beams according to a target region (e.g., a treatment region, etc.). The leaf unit2202may be connected to the driving unit2201by a transmission piece (not shown in the figure). Details regarding the transmission piece may be found elsewhere in the present disclosure. See, for example,FIG. 23and the description thereof. The driving unit2201and the leaf unit2202may be spaced from each other. There may be more installation space for the driving unit2201without the limitation of the leaf unit2202.

FIG. 22-B illustrates an exemplary construction of the driving unit2201in MLC2200. The driving unit2201may include a motor supporting base2203, a plurality of motors2204, and a motor brace2205. The motor2204may provide a driving force to the leaf unit2202. The motor2204may be placed on the motor supporting base2203. The motor brace2205may be placed on the motor supporting base2203. The motor2204may be fixed by the motor brace2205. The motor supporting base2203and the motor brace2205may be integrated into one piece, or two independent pieces connected using a connection piece. The motors2204may be placed in one or more layers. The motors2204may be placed toward a single direction or different directions (e.g., opposite directions, etc.). For instance, the layer arrangement for the motors2204may be determined based on the spatial configuration of a device that may be used with the MLC2200. As shown inFIG. 22-B, the motors2204may be placed in an upper layer and a lower layer arranged in multiple rows. The motors2204in an upper layer and the motors2204in a lower layer below the upper layer may be toward opposite directions. The diameter of the motor2204may be, for example, 10 mm.

FIG. 22-C illustrates an exemplary configuration of the leaf unit2202. As shown inFIG. 22-C, the leaf unit2202may include a guiding box2206and at a leaf2207. The guiding box2206may be configured with a leaf guiding groove (not shown in the figure). The leaf guiding groove may hold and guide the leaves2207. A leaf2207may be placed into a corresponding leaf guiding groove. The leaf2207may undergo a reciprocal movement in the leaf guiding groove. The MLC2200may provide a desired conformal shaping of radiation beams based on the shape of a target region through the movements of the leaves2207. A leaf2207may be made from a material that has properties including, for example, high density, high hardness, proper machinability, or the like, or a combination thereof. The leaf2207may be made of, for example, tungsten, aluminum, magnesium, stainless steel, copper, or the like, or an alloy thereof. The thickness of the leaf2207may influence the conformal shaping of radiation beams. The thickness of the leaf2207may be from 0.8 mm to 2.2 mm, from 0.8 mm to 1.6 mm, from 0.8 mm to 1.3 mm, from 1.0 mm to 1.8 mm, from 1.0 mm to 1.5 mm, etc.

FIG. 23-A toFIG. 23-D illustrate an exemplary configuration of MLC2200according to some embodiments of the present disclosure.FIG. 23-A andFIG. 23-B illustrate MLC2200with the leaf2207retracting to the guiding box2206.FIG. 23-C andFIG. 23-D illustrate MLC2200with the leaf2207extending out of the guiding box2206. As shown inFIG. 23-A, the MLC2200may further include a worm2301, a gear2302, a transmission line2303, a first guiding wheel2304, a spring2305, a supporting base2306, and a guiding bar2307. The worm2301and the gear2302may change the direction of the rotational motion output by the motor2204. Details regarding to the worm2301and the gear2302may be found elsewhere in the present disclosure. See, for example,FIG. 24and the description thereof. The transmission line2303may transmit movement from the motor2204to a leaf2207, and/or provide a pulling force to the leaf2207. The transmission line2303may be made from a non-magnetic material. For instance, the transmission line may include a steel wire. The first guiding wheel2304may guide the transmission line2303. The spring2305may be in a compressed state. The spring2305may provide an elastic force to the leaf2207. The guiding bar2307may hold and/or guide the spring2305. The spring2305and the guiding bar2307may be made from a non-magnetic material including, for example, stainless steel, copper, or the like, or an alloy thereof. The MLC2200may further include a shell (not shown in the figure). The shell may cover the motor2204and shield the motor2204from a magnetic field. The shell may be made from a non-magnetic material including, for example, stainless steel, aluminum, or the like, or an alloy thereof. The shell may be the shell1801as illustrated inFIG. 18and the description thereof.

The motor2204may be connected to the transmission line2303with the worm2301and the gear2302. The transmission line2303may be connected to the leaf2207through the first guiding wheel2304. Details regarding connection between the transmission line2303and the leaf2207may be found elsewhere in the present disclosure. See, for example,FIG. 25and the description thereof. The first guiding wheel2304may be placed on the supporting base2306. One end of the guiding bar2307may be fixed on the supporting base2306. The other end of the guiding bar2307may be connected to the leaf2207. The end of the guiding bar2307connected with the supporting base2306may bend, which may reduce the length of the MLC2200along the horizontal movement of the leaf2207. One end of the spring2305may be fixed on the supporting base2306. The other end of the spring2305may be connected to the leaf2207. Details regarding connection between the spring2305and the leaf2207may be found elsewhere in the present disclosure. See, for example,FIG. 25and the description thereof. The spring2305may be placed around the guiding bar2307. The spring2305may deform along the guiding bar2307.

An output end of the motor2204may be connected with the worm2301. The worm2301may mesh with the gear2302and drive the gear2302. When the motor2204is operating, the worm2301may undergo a rotational motion in a direction, then the gear2302may undergo a rotational motion in a different direction. The transmission line2303may pass through the first guiding wheel2304, and be connected to the leaf2207. For the purposes of illustration, the length of the transmission line2303may be shorter when the motor2204undergoes clockwise rotation; the length of the transmission line2303may be longer when the motor2204undergoes an anticlockwise rotation.

When the motor2204undergoes a clockwise rotation, the length of the transmission line2303may be shorter. The transmission line2303may provide the pulling force to the leaf2207. The leaf2207may retract to the guiding box2206. When the motor2204undergoes an anticlockwise rotation, the length of the transmission line2303may be longer. The spring2305in a compressed state may provide an elastic force to the leaf2207such that the leaf2207may stretch out of the guiding box2206. The elastic force provided by the spring2305may be greater than the gravity that the leaf2207is subject to. By this way, the transmission line2303and the spring2305in concert may control the movement of the leaf2207. An angle between the elastic force provided by the spring2305and the pulling force provided by the transmission line2303may be 175-185 degrees.

FIG. 24illustrate details regarding the configuration of the MLC2200according to some embodiments of the present disclosure. As shown inFIG. 24, the motor brace2205may include a gear brace2401and a reeling wheel2402. The gear2302may be fixed on the motor brace2205by the gear brace2401. The reeling wheel2402and the gear2302may be arranged coaxially and undergo a rotational motion coaxially. When the speed of the motor2204is constant, the speed of the gear2302may be constant. When the speed of the reeling wheel2402may be constant, the speed of the leaf2207may increase with the diameter of the reeling wheel2402. The speed of the leaf2207may increase by increasing the diameter of the reeling wheel2402. The transmission line2303may be wrapped around the reeling wheel2402. The reeling wheel2402may include an encoder (not shown in the figures). The encoder may detect the displacement of the leaf2207. The reeling wheel2402and the encoder may be arranged coaxially and undergo a rotational motion coaxially. The number of rounds of the encoder detected by the encoder may be equal to the number of rounds of the reeling wheel2402. The circumference of the reeling wheel2402may be measured. The displacement of the leaf2207may be determined by multiplying the circumference of the reeling wheel2402by the number of rounds of the reeling wheel2402.

The MLC2200may further include a second guiding wheel2404. The second guiding wheel2404may guide the transmission line2303. The second guiding wheel2404may be fixed on the motor brace2205by a guiding wheel brace2403. The transmission line2303may be connected to the leaf2207with stretching out of the reeling wheel2402and passing through the second guiding wheel2404. The second guiding wheel2404may include an encoder2405. The encoder2405may detect the displacement of the leaf2207. The second guiding wheel2404and the encoder2405may be arranged coaxially and undergo a rotational motion coaxially. The number of rounds of the encoder2405detected by the encoder2405may be equal to number of rounds of the second guiding wheel2404. The circumference of the second guiding wheel2404may be measured. The displacement of the leaf2207may be determined by multiplying the circumference of the second guiding wheel2404by the number of rounds of the second guiding wheel2404.

When the motor2204is operating, the worm2301may rotate in a direction. Due to the mesh between the worm2301and the gear2302, the gear2302may rotate in a direction different from the rotation direction of the worm2301. For instance, the gear2302may rotate in a direction perpendicular to the rotation direction of the worm2301. When the motor2204stops operating, the spring2305in a compressed state may provide an elastic force to the leaf2207. The leaf2207may provide a pulling force to the reeling wheel2402. The gear2302may undergo a rotational movement with the rotating reeling wheel2402. The leaf2207may undergo linear movement. In order to prevent the leaf2207from moving when the motor2204stops operating, the worm2301and the gear2302may be self-locking. Self-locking, as used herein, may be that the gear2302may undergo a rotational motion when the worm2301undergoes a rotational motion; the worm2301may not undergo a rotational motion when the gear2302undergoes a rotational motion. Due to the self-lock between the worm2301and the gear2302, the worm2301may not rotate and the leaf2207may stop moving when the motor2204stops operating.

The transmission line2303may wrap around the reeling wheel2402, and pass through the first guiding wheel2304and the second guiding wheel2404, connecting the reeling wheel2402and the leaf2207. By changing the locations and/or the orientations of the first guiding wheel2304and/or the second guiding wheel2404, the location of a motor2204may be changed. By changing the location of a motor2204, the relative location of the motor2204and the leaf2207may be changed. When the MLC2200is used in a magnetic field, the motor2204may be placed away from the magnetic field, and the influence between the motor2204and the magnetic field may be reduced. The motors2204may be placed such that the distances between different motors2204may be different. By this way, there may be more installation space for encoders used to detect displacement of the leaves2207in the driving unit2201.

FIG. 25-A andFIG. 25-B illustrate an exemplary configuration of the leaves2207according to some embodiments of the present disclosure.FIG. 25-A illustrates the front side of the leaves2207. The back side of a leaf2207, as used herein, may be the left side of the leaf2207along the horizontal movement of the leaf2207.FIG. 25-B illustrates the back side of the leaves2207.

As shown inFIG. 25-B, a leaf2207may include a leaf tail2501. The leaves2207may be located in one or more rows. The leaf tail2501may operationally connect the transmission line2303and the leaf2207. The leaf tail2501may operationally connect the spring2305and the leaf2207. The leaf tail2501may include a sliding groove. The guiding bar2307may enter or exit the sliding groove when the leaf2207is moving, so that the leaf2207moves relatively to the guiding bar2307. The sliding groove may be located on the guiding bar2307. The leaf tail2501may include a structure congruous with the sliding groove.

In order to avoid collision of the spring2305and the guiding bar2307, the leaf tails2501may be located at different locations on the neighboring leaves.