Patent ID: 12208284

DETAILED DESCRIPTION

High-Level Overview of a LINAC Radiotherapy Device

FIG.2shows a known LINAC200, suitable for delivering, and configured to deliver, a beam of radiation to a patient during radiotherapy treatment. In operation, the LINAC device200produces, modulate and shapes a beam of radiation and directs it toward a target region within the patient's body or skin in accordance with a radiotherapy treatment plan.

A medical LINAC machine is by necessity complex, with many inter-operating component parts. A brief summary of the operation of a typical LINAC will be given with respect to the LINAC device200showed inFIG.2which comprises a source of radiofrequency waves202, a waveguide204, a source of electrons206, a system capable of creating a strong vacuum comprising one or more vacuum pumps230, a heavy metal target which produces X-rays when hit by an electron beam, and a complex arrangement of magnets capable of re-directing and focusing the electron beam onto the target. The device200depicted inFIG.2also comprises a treatment head which houses various apparatus configured to, for example, collimate and shape the resultant X-ray beam.

The source202of radiofrequency waves, such as a magnetron, produces radiofrequency waves. The source202of radiofrequency waves is coupled to the waveguide204, and is configured to pulse radiofrequency waves into the waveguide204. Radiofrequency waves pass from the source202of radiofrequency waves through an RF input window and into a RF input connecting pipe or tube. A source206of electrons, such as an electron gun, is coupled to the waveguide204and is configured to inject electrons into the waveguide204. In the source206of electrons, electrons are thermionically emitted from a cathode filament as the filament is heated. The temperature of the filament controls the number of electrons injected. The injection of electrons into the waveguide204is synchronised with the pumping of the radiofrequency waves into the waveguide204. The design and operation of the radiofrequency wave source202, electron source206and the waveguide204is such that the radiofrequency (RF) waves accelerate the electrons to very high energies as they propagate through the waveguide204. The design of the waveguide204depends on whether the LINAC200accelerates the electrons using a standing wave or travelling wave, though the waveguide typically comprises a series of cells or cavities, each cavity connected by a hole or ‘iris’ through which the electron beam may pass. The cavities are coupled in order that a suitable electric field pattern is produced which accelerates electrons propagating through the waveguide204.

As the electrons are accelerated in the waveguide204, the electron beam path is controlled by a suitable arrangement of steering magnets, or steering coils, which surround the waveguide204. The arrangement of steering magnets may comprise, for example, two sets of quadrupole magnets.

Once the electrons have been accelerated, they pass into a flight tube. The flight tube may be connected to the waveguide204by a connecting tube. This connecting tube or connecting structure may be called a drift tube. The drift tube also forms part of a vacuum tube. RF waves exit the waveguide204via an RF output connecting pipe or tube coupled with the drift tube. As with the RF input pipe which introduces RF to the waveguide204, the pipe or tube through which RF exits the waveguide204connects to the vacuum tube via an elbow joint or ‘T-shaped’ joint. RF passes out from the vacuum system via an RF output window which seals the vacuum system.

The flight tube is kept under vacuum conditions by the pump system. The electrons travel along a slalom path toward the heavy metal target. The target may comprise, for example, tungsten. Whilst the electrons travel through the flight tube, an arrangement of focusing magnets act to direct and focus the beam on the target. The slalom path allows the overall external length of the LINAC200to be reduced while ensuring that the beam of accelerated electrons, which is comprised of electrons with a small spread of energies, is focused on the target.

To ensure that propagation of the electrons is not impeded as the electron beam travels toward the target, the waveguide204is evacuated using a vacuum system comprising a vacuum pump230or an arrangement of vacuum pumps. The pump system is capable of producing ultra-high vacuum (UHV) conditions in the waveguide204and in the flight tube. The vacuum system also ensures UHV conditions in the electron gun. Electrons can be accelerated to speeds approaching the speed of light in the evacuated waveguide204.

Together, the electron gun206, waveguide204and the flight tube form a vacuum tube in which electrons can be accelerated and directed toward a target in vacuum conditions. In implementations comprising a drift tube connecting the waveguide204to the flight tube, the drift tube also forms part of the vacuum tube. To produce the necessary high vacuum conditions, the vacuum system may undergo several stages of pumping before a high quality vacuum may be maintained using e.g. ion pumps. For example, first, a normal piston-based pump may be used, followed by a stage wherein the pressure inside the vacuum system is further lowered using a turbo-molecular pump. Finally, ion pumps are used to ensure the system is kept at ultra-low pressure.

When the high energy electrons hit the target, X-rays are produced in a variety of directions. The target is located inside the flight tube, and is located at the end of the flight tube to seal the vacuum system. The flight tube also comprises a target window, which is transparent to X-rays, which is positioned to allow the X-rays which are produced when the LINAC200is in operation to pass from the evacuated flight tube through the target window and into the treatment head210. At this point, a primary collimator blocks X-rays travelling in certain directions and passes only forward travelling X-rays to produce a cone shaped beam. The X-rays are filtered, and then pass through one or more ion chambers for dose measuring. The beam can be shaped in various ways by beam-shaping apparatus, for example by using a multi-leaf collimator, before it passes into the patient as part of radiotherapy treatment.

In some implementations, the LINAC200is configured to emit either an X-ray beam or an electron particle beam. Such implementations allow the device to provide electron beam therapy, i.e. a type of external beam therapy where electrons, rather than X-rays, are directed toward the target region. In such implementations, it is possible to ‘swap’ between a first mode in which X-rays are emitted and a second mode in which electrons are emitted by adjusting the components of the LINAC. In essence, it is possible to swap between the first and second mode by moving the heavy metal target in or out of the electron beam path and replacing it with a so-called ‘electron window’. The electron window is substantially transparent to electrons and allows electrons to exit the flight tube.

The end of the flight tube may be sealed by a component which comprises both a target and an electron window. It is then possible to swap between the first and second mode by moving the flight tube such that the electron beam points toward either the target or the electron window. The drift tube, which connects the waveguide to the start of the flight tube, is therefore slightly flexible to allow the flight tube to move. In other words, the flight tube will move when the user changes between using an electron and XRay energy, this puts either the tungsten target (XRAY) or electron window (Electron) in position to treat.

A typical LINAC device such as the device200shown inFIG.2also comprises several other components and systems. The whole system is cooled by a water cooling system (not shown in the figures). The water cooling system may be used, in particular, to cool the waveguide204, target, and radiofrequency source202. In order to ensure the LINAC does not leak radiation, appropriate shielding is also provided. As will be understood by the person skilled in the art, a LINAC device used for radiotherapy treatment will have additional apparatus such as a gantry to support and rotate the LINAC, a patient support surface, and a controller or processor configured to control the LINAC.

The present application relates, in particular though not exclusively, to a controller that is configured to control a LINAC device or devices. In particular it relates to the control of rotatably moveable parts of a LINAC device such as a rotatable gantry and/or a rotatable beam collimator, as discussed further below.

Rotatable Gantry

FIG.3shows a cross section through a co-planar LINAC radiotherapy device320configured to provide co-planar radiotherapy treatment. A patient308is shown located on a table or other support surface310, within the central part of the device320.

The device320comprises a rotatable housing or gantry304. The gantry304is generally rotatable about the centrepoint of the depicted cross-section—i.e. the gantry's304axis of rotation is generally perpendicular to the plane of the depicted cross-section. The gantry304has a therapeutic radiation source300mounted thereon and a therapeutic radiation detector302. In the arrangement shown, the therapeutic radiation detector302is mounted substantially diametrically opposite the therapeutic radiation source300, on a circular support track306of the gantry304. Therefore rotation of the gantry304causes rotation of the therapeutic radiation source300and of the detector302, in this arrangement. Moreover, the detector302and the therapeutic radiation source300are arranged to rotate together around the circular support track306, such that they are always arranged substantially 180 degrees from one another (i.e. diametrically opposite one another) around the gantry304. In this arrangement, there is also an imaging radiation source314and an imaging radiation detector316, arranged substantially diametrically opposite one another on the gantry304.

The therapeutic radiation source300is arranged to emit a targeted X-ray beam, directed towards a tumour or other target area within the patient's body or on a patient's skin. The therapeutic radiation detector302is arranged to detect the beam, once it has passed through the patient's body. The directionality of the beam is controlled, at least in part, by one or more collimators, which are discussed below.

In operation of the LINAC320, therapeutic radiation is emitted in the plane of the depicted cross section, i.e. perpendicular to the axis of rotation of the therapeutic radiation source300, therapeutic radiation detector302and gantry304. Radiation can thus be delivered to a radiation isocentre313at the centrepoint of the gantry304, regardless of the angle to which the therapeutic radiation source300is rotated. This therefore enables the therapeutic radiation source300to direct radiation towards a tumour or other target area within or on the patient108, from various different angles around the patient108. As discussed above, this is an important feature of any therapeutic radiotherapy device, to ensure that the radiation does not have to repeatedly pass through the same portion of healthy tissue within the patient, in order to reach the target area. Instead, the therapeutic radiation source300can be rotated to different rotational angles, so that the radiation beam passes through multiple different healthy areas, each for a limited time period, during the therapeutic radiotherapy treatment of the tumour or other target area.

Collimation of the Beam

In order to target a tumour or other target area and reduce the exposure of healthy tissue to radiation, it is important to locate the patient correctly within a therapeutic radiotherapy device, so that the target area is at the radiation isocentre313. Thus, the table or other support surface308on which the patient is located is usually linearly moveable both vertically and horizontally. In some arrangements, the table is also rotatable along the vertical axis through the radiation isocentre (i.e. rotatable about the Z-axis) for non-coplanar treatment. Moreover, in order to successfully target the tumour or other target area, the shape of the radiation beam should be arrangeable to fit the shape, size and nature of the tumour, as closely as possible.

Most tumours can be targeted using a combination of block collimators and a so-called “multi-leaf” collimators (MLC's). A block collimator is usually a solid block of radiopaque material such as tungsten, which usually has a straight front edge that spans the entire width of an aperture, from which the radiation beam is emitted, and which can be advanced and/or withdrawn across the aperture in a direction transverse to the front edge. Thus, the block collimator has the effect of adjusting the width of the aperture as needed. A pair of such collimators arranged face-to-face can thus narrow the aperture from both opposing sides. A multi-leaf collimator (MLC) comprises an array of long, narrow, deep leaves' of radiopaque material that, in some arrangements, can each be extended into and out of the aperture. Arranged side-by-side in an array; the tips of the leaves therefore define a chosen shape which can be varied at will by extending or retracting individual leaves.

FIG.4shows a view along the beam axis of a known collimation arrangement. The purpose of the collimators is to allow the transmission of a beam which has a desired cross-section and to provide as complete shielding as possible across the remainder of the beam field (i.e. the maximum extent of the beam). To allow shaping of the beam, a multi-leaf collimator (MLC)410is provided which comprises a series of individual leaves412of a radiopaque material such as tungsten, arranged side-by-side relative to each other, in two opposing arrays410a,410b. Thus, the lower array410aextends into the beam field in the x direction from one side of the field, and the upper array410bextends into the beam field in the x direction from the opposing side of the field. Each leaf412can each be moved independently of the others so as to define a chosen shape414between the tips of the opposing leaf banks410a,410b. Each leaf is thin in its transverse (y) direction to provide good resolution, is deep in the (z) direction to provide adequate absorption, and long in its longitudinal (x) direction to allow it to extend across the field to a desired position. Generally, the longitudinal length of the leaf will be greater than its depth, and both will be much greater than its transverse thickness.

According to an arrangement described herein, the control of which is described further below, the collimator is provided on or within a radiation head (such as the therapeutic radiation source300described above in relation toFIG.3a), which is attached to a rotatable gantry of a LINAC device. The therapeutic radiation beam from the radiation head is directed towards the isocentre of gantry rotation and the collimator delimits the beam to a desired beam shape. The collimator may include a block collimator. In this arrangement, it comprises an MLC such as the one shown inFIG.4which has two opposing banks or arrays of leaves, each leaf being moveable in one direction to delimit the beam into a desired shape of e.g. a tumour or other target area.

In the example shown inFIG.4each leaf412is laterally moveable in the x direction only. The extent to which the MLC can achieve different beam shapes is therefore limited. According to an arrangement, in order to enhance the extent to which the MLC can achieve different beam shapes, the MLC is also rotatable about the beam propagation axis (shown as the y axis inFIG.4.) Rotating the MLC rotates the rotational angle of the leaves and thus enables the MLC to achieve a greater number of different beam shapes. It therefore enhances the bespoke targeting of tumours or other target areas, that is achievable by the LINAC device.

Control of a Therapeutic Radiotherapy Device

An improved controller for controlling a therapeutic radiotherapy device, such as a LINAC device, according to an arrangement described herein, is provided, as shown inFIG.5, which comprisesFIGS.5(a),5(b) and5(c). The controller600in this arrangement acts as a single controller that is operable to control operation of a LINAC device (not shown inFIG.5), either independently or in conjunction with a machine-based User Interface Module (UIM) that is also described further below. The controller600can therefore replace the multiple handheld controllers that known LINAC systems typically require.

The controller600embodies intelligent recognition of which functions are required by a user, in order to control operation of a LINAC device. This includes recognition of which functional features are typically used at mutually-exclusive times, which features are typically used at similar times and which patterns of movement and control are natural and intuitive for a user to make, when using a handheld device. The controller600is sized so as to be handheld by the user. In fact, the controller600is particularly compact and user-friendly and, at least in the particular arrangement described in relation toFIG.5herein, is generally smaller than the handheld controllers of known LINAC devices.

Looking first atFIG.5(a), which shows a front view of the controller600, it can be seen that the controller600in this arrangement has a substantially rectangular profile, with rounded corners for improved ergonomic feel and comfort. The front elongate face, which is to be held facing the user's line of sight when the controller600is in use, comprises a user input surface602. The user can provide input to the controller600via various features on the user input surface602, in order to control aspects of the corresponding therapeutic radiotherapy device's operation.

In the arrangement ofFIG.5, the controller600comprises, provided on the user input surface602, a number of user-depressible buttons604, which enable the user to make selections. It also comprises a substantially cross-shaped actuator606, wherein the ends of each of the four branches of the cross-shaped actuator606can be depressed by the user. Also provided on the user input surface602is a user-actuatable dial608. This dial608can be used to control movement of rotatable components of a therapeutic radiotherapy device, with continuously variable speed, as will be discussed further below. The user input surface602also comprises a separate ‘table controller’ actuator620that can be used to control movements of the patient table within a therapeutic radiotherapy device, as will also be discussed further below.

The user-actuatable dial608(also referred to herein as a so-called ‘thumb dial’608) is substantially circular, with an outer ring610and an inner, substantially circular button612, located within the outer ring610. The inner substantially circular button612comprises a ‘thumb dial function selector’612, as discussed further below. The surface of the dial608, via which the user can input control signals to the therapeutic radiotherapy device, is generally co-planar or ‘flush’ with the user-input surface602of the controller600. However the surface of the dial608can be slightly raised or lowered with respect to its surrounding area(s) on the user-input surface602, in order to provide improved tactile feedback to the user regarding the location of the dial608and to prevent the dial608from being accidentally actuated when the user does not intend to actuate it. Alternatively or additionally, the surface material of the dial608, and in particular of the outer ring610, can have a different material feel to some or all of the other parts of the user-input surface602, in order to increase tactile user feedback, and in order to provide improved user grip on the surface of the dial, for enhanced control. For example, the outer ring610may be formed from the same material as the rest of the user-input surface602, but may be configured to have a different tactile feel, to the user's touch.

The dial608includes an upper position marker614located on the outer ring610. The upper position marker614is provided substantially at 12 o'clock (or 0 degrees) on the outer ring610. The upper position marker614is shown inFIG.5as a raised notch on the surface of the outer ring610, but it could be any suitable type of position marker, which can provide visual and/or tactile feedback to the user, regarding its instantaneous position. It is helpful for the upper position marker614to provide both visual and tactile feedback to the user, regarding its position. It can also be helpful for the position marker614to be raised, to enable the user to effectively push the marker614with his or her finger or thumb, to move the outer ring610and thereby provide control input to the dial608.

In the arrangement shown inFIG.5, there are also two side position markers615, located at 3 o'clock and 9 o'clock (or 90 degrees and 270 degrees) on the outer ring610, respectively. These can be physically similar to the upper position marker614, discussed above, and serve a similar purpose.

The dial608is arranged for the outer ring610to be rotatable by the user. The outer ring610is rotatable about its central axis, which extends perpendicular to the plane of the user-input surface602(i.e. about the z axis as shown inFIG.5.) Therefore the outer ring610rotates substantially within the plane of the user-input surface602of the controller600. In the arrangement shown, the upper position marker614is located, when the dial is in a resting position and is not being rotated by the user, at the ‘12 o'clock’ or 0° position. As shown inFIG.5herein, the outer ring610is rotatable at least to the extent that the marker614can move a one-sixth turn to each of the left and the right (i.e. clockwise and anti-clockwise, from 10 o'clock to 2 o'clock, −60° to +60°.) A physical limiter (not shown inFIG.5) is provided underneath the surface of the dial608, in order to limit the rotation.

In principle, the user can rotate the dial608by having their finger(s) or thumb on any part of the outer ring610, but many users will prefer to have their finger(s) or thumb on one of the position markers614,615(particularly if it is a raised marker such as those shown inFIG.5) and to impart the rotary controls via movement of the markers614,615. Because the dial608is substantially flush with the plane of the user-input surface602of the controller600, the user's movements to actuate the dial are substantially within that plane. The user does not need to lift his or her thumb in order to actuate the dial. Therefore the user movement's required for actuating the dial are intuitive and comfortable. This is advantageous, especially for users who user the controller600repeatedly and/or for long periods of time, during their working day.

The marker positions inform the user of the dial's instantaneous position, relative to its zero or resting position. As detailed below, during operation of the controller600, the rotation of the dial608can be used to selectively determine the speed of rotation of the gantry and of the collimator of the corresponding LINAC device, wherein (generally speaking), the greater the size of the actuation, the greater the so-called ‘dialling angle’ of the dial608, and therefore the greater the speed of the component under control. The rotation speed increases when the dial is pushed away from its neutral position. The rotation speed decreases when the dial is pushed towards the neutral position. The mapping of the rotation angle of the dial608to the speed of movement of the selected component is not a straight line but a curve. That is; the increment of speed is smooth at the beginning of the dial's rotation and then becomes more stiff when approaching the end)(±60°. If the dial is released, at any time, it is spring-biased to return to its neutral/zero position. When the dial returns to its neutral/zero position, movement of the selected component stops immediately.

In addition to the size of the actuation of the dial608controlling the speed of rotation of the selected component of the LINAC device, the direction of the actuation of the dial also controls the direction in which the selected component will rotate. That is; if the dial608is actuated in a clockwise direction, away from its neutral position, the selected component will rotate in a positive direction, up to 180 degrees from its starting position. Conversely, if the dial608is actuated in an anti-clockwise direction, away from its neutral position, the selected component will rotate in a negative direction, up to 180 degrees from its starting position. The speed at which the selected component rotates will be governed by the size of the angle to which the dial is rotated, in the relevant direction. The angular extent to which the selected component will rotate, in response to an actuation of the dial608, will depend on the speed of rotation and on the length of time for which the actuation occurs.

In order for user-input on the dial608to be translated into motion control of the gantry and/or collimator, the controller600includes a potentiometer. The basic operation of a potentiometer is well known and so is not described in detail herein. Very briefly; a potentiometer comprises an adjustable voltage divider, which typically has a resistive element with end terminals on each end—which, in this case, connect to other control circuitry within the controller— and a sliding contact which moves along the resistive element, making good contact with one point on the resistive element. The sliding contact is connected to a third terminal, housed between the two end terminals. Movement of the sliding contact—in this case, in an arc about the resistive element—changes the output voltage of the potentiometer, in accordance with the position of the sliding contact.

In the controller600described herein, the dial608connects to the potentiometer such that the position of the potentiometer's sliding contact, and therefore the output of the potentiometer, is changed by changing the angular position of the dial608. The user can therefore use the dial608, making adjustments relative to the neutral/zero position to which the dial608is biased to return, in order to change the output of the potentiometer. The control circuitry within the controller600can use the output of the potentiometer to convey a corresponding control signal to the LINAC device.

In this arrangement, the controller600has a safety feature comprising a so-called ‘enable bar’630. The enable bar630in fact comprises (in this arrangement) two buttons—one provided on the left side face of the controller600and the other provided on the right side face of the controller600. Both enable bar buttons630comprise elongate substantially rectangular depressible buttons. Because the enable bar buttons630are provided on both sides of the controller600, they are easy for the user to actuate, regardless of which hand he or she is holding the controller600in. The enable bar buttons630provide a safety feature because, in order to authorise the dial608to control gantry and/or collimator movement, as discussed above, the user must press or squeeze the enable bar (one or both buttons)630at the same time as actuating the dial608. If the enable bar button(s)630is/are released, the selected component of the LINAC will immediately stop moving, even if the dial608is currently at a non-zero rotational position. The enable bar630therefore provides a safety backstop, against possible unintentional movement of the LINAC components, in the event that the user accidentally moves the dial609when he or she does not intend to do so. The enable bar also authorises the movements to be initiated and maintained by other moveable components of the Linac such the patient table and the panels, in accordance with current regulatory requirements.

According to the arrangement ofFIG.5, the dial608can be used to selectively control both the gantry and the collimator (or so-called ‘Beam Limiting Device’ BLD), wherein the user inputs a selection to the controller600, to determine which of those two components is to be controlled at a given time. As mentioned above, the table is controlled separately, as detailed further below. The user's selection of whether to actuate the gantry or the collimator is input, in this arrangement, via the thumb dial function selector612. The thumb dial function selector612is a depressible button, provided in the centre of the dial608, which in use the user can press with any digit but he or she is likely to depress it using his or her thumb. Therefore the user does not need to move his or her hand in order to both select which component to control and subsequently to control its rotation, using the improved controller600. The thumb dial function selector612enables the user to scroll through3different options, in this arrangement: gantry rotation, Linac ASU (Automatic Setup) and collimator rotation. Linac Automatic Setup (ASU) triggers movement of the gantry and the collimator to a pre-determined set of positions, which have been programmed (into a suitable controller within or associated with the Linac) on a patient-specific basis.

The default option for the dial608in this arrangement is control of gantry rotation, but the thumb dial function selector612can be pressed (in this case) once to change to Linac ASU and a further time to change to collimator rotation (and another time to return to gantry rotation). It is configured to make a noise such as an audible ‘beep’ when the thumb dial function selector612is pressed. In addition, there is a thumb dial function indicator613, comprising three LED portions corresponding to the gantry, Linac ASU and collimator respectively, wherein one of the three LED portions of the thumb dial function indicator613is illuminated to indicate which option has been selected by the thumb dial function selector612at a given time.

Thus, it can be seen that the provision of the thumb dial function selector612provides a neat, intelligent and user-friendly way in which space is saved on the surface of the controller600, by enabling the gantry and collimator of the Linac, and the activation of Linac ASU, all to be controlled via a single, relatively small region of the controller (comprising the dial608and the thumb dial function selector612). The user is prevented from accidentally rotating the wrong Linac component, via the LED's on the thumb dial function indicator613. Moreover, the user is prevented from accidentally rotating a component by inadvertently touch the dial608when he or she does not intend do, via the requirement for the enable bar630to also be depressed, in order for the dial608to cause the Linac component(s) to rotate, or to revert to their Automatic Setup (ASU) positions.

The controller600in this arrangement also comprises a table controller620for controlling movement of the table (not shown) on which the patient is positioned, within the Linac. The table controller620is physically distinct to the dial608—in this arrangement, it is provided just below the dial608, on the surface of the controller600. So, very little user movement is required to switch between controlling the rotatable components and controlling the table movement. In this arrangement, the table controller620is located so that its centre is approximately 45 mm below the centre of the dial608, on the surface of the controller600. However in other arrangements this distance may be different—for example the respective centres (or the respective actuatable parts) of the dial608and the table controller620may be between 20 mm and 70 mm apart, or between 30 mm and 60 mm apart or between 40 mm and 50 mm apart.

The table controller620can control both vertical and horizontal movement of the table. There is a table movement mode selector622provided just below the table controller620, wherein the table movement mode selector622is a depressible button that can be pressed to switch between vertical movement mode (which is the default position) to horizontal movement mode. When the horizontal movement mode has been selected, a ‘table horizontal movement mode indicator’624, which in this arrangement comprises a substantially circular backlight surrounding the table controller620, is illuminated. When the vertical movement mode has been selected (or defaulted to), the table horizontal movement mode indicator624is not illuminated.

The table controller620in this arrangement comprises a so-called ‘4-way slider’ with continuous variable speed and a default neutral position. When vertical table movement is selected, pushing the slider up (towards the top of the elongate user input surface602of the controller600), causes the table to move upwards (i.e. in the + direction along the z axis), and pushing the slider down (towards the bottom of the elongate user input surface602of the controller600), causes the table to move downwards (i.e. in the − direction along the z axis). When horizontal table movement is selected, pushing the slider up causes the table to move in the +y direction in an x-y plane, whereas pushing the slider down causes the table to move in the −y direction in the x-y plane. When horizontal table movement is selected, pushing the slider to the right causes the table to move in the +x direction in an x-y plane, whereas pushing the slider to the left causes the table to move in the −x direction in the x-y plane.

As with the dial608, there is a safety mechanism associated with the table controller620in this arrangement, wherein actuating the table controller620will only give rise to movement of the table if one or both of the enable bar buttons630is also depressed at the same time. Releasing the table controller620to its neutral position and/or releasing the enable bar button(s)630will cause immediate cessation of the table movement, in this arrangement. The extent to which the table controller620is pushed in a selected direction will determine the speed at which the table moves, in the corresponding direction, wherein the speed increases as the table controller slider moves further from its neutral position, and decreases as it nears its neutral position The user is provided with one or more screens (not shown in the figures) that can provide geometric readings relating to table/gantry/collimator positions.

The controller600also comprises panel shift controls which, in this arrangement, are physically distinct to both the dial608and the table controller620and comprise a cross-shaped actuator606and a substantially circular panel centring button607, provided in the middle of the cross-shaped actuator606. There are two panels (neither shown inFIG.5) in the Linac, which can be controlled by the panel shift controls. As will be known to the skilled reader; both panels are configured to detect X-rays but at different respective energy levels—one is configured for kV detection and the other is configured for MV. The default panel is a kV panel (also referred to in this arrangement as an ‘XVI’ panel). The other panel is an MV panel (also referred to in this arrangement as an ‘iView’ panel). There is a depressible iView (MV) mode button640, provided substantially below the cross-shaped actuator606, which can be pressed to change control from the kV panel to the MV panel. There is an iView (MV) panel mode indicator642which illuminates when the MV panel has been selected for control.

The panel centring button607can be depressed, for the selected panel, in order for it to move to its centralised position. The cross-shaped actuator can then be used to move the selected panel in the x and y directions, both positively and negatively with respect to centre (i.e. up and down, left and right) by depressing the corresponding branch of the cross. The panels are configured to move to a maximum/limit position, in the corresponding direction, when the respective branch of the cross-shaped actuator606has been pressed.

The enable bar630also acts as a safety mechanism with respect to panel movement, wherein the panel shift controls will only impart movement to the panel(s) if the enable bar button(s) is/are also depressed at the same time as the panel shift controls are actuated.

The controller600also comprises some additional buttons in this arrangement, shown general in the lower region604inFIG.5. For example, the buttons may include controls for activating a room light for the room in which the Linac is situated, for activating a torch within the controller, for activating a laser beam for marking a target region for the therapeutic radiation to be applied to, and so on. There is also an LED bar towards the bottom of the user input face602, which is illuminated when the controller600is switched on.

As shown inFIG.5(b), there are also some actuators on the rear face of the controller600in this arrangement. These include a ‘reset motors’ button and a ‘touchguard override’ button652, which can be used in conjunction with the enable bar630to override any pre-set inhibits or limits that have been put in place in relation to any of the moving parts of the Linac. It can be seen that these two actuators are intelligently placed on the rear surface of the controller600since they are likely to be used very infrequently.

Turning again to the functionality of the dial608;FIG.7(a)herein shows the dial608in isolation, not in situ within the controller600. In addition to the outer ring610and the depressible thumb dial function selector612, the dial mechanism comprises an upper housing802and a lower housing804and screw holes806for attaching it into the body of the controller600.

Looking atFIG.7(b); it can be seen that the rear side of the dial608comprises a first cog810and a second cog812. The first cog810is actuated via the user actuating the outer ring610, on the front surface of the dial608. Movement of the first cog810drives the second cog812, to which the potentiometer814connects. There is also a microswitch808substantially at the centre of the rear view of the dial608, which is actuated via the user depressing the thumb dial function selector612on the front surface of the dial608. The microswitch808connects to a PCB (not shown) in order to convey control signals when the thumb dial function selector612is pressed.

FIG.7(c)is a rear view of the dial608with the lower housing804and the cogs810,812removed. As can be seen therein, there is a spring816located in a groove818which is situated radially outward of where the first cog810would be, if shown. The spring816serves to bias the dial608back to its zero position when it is not being actuated. There is a peg820which extends rearwardly from the upper position marker614(which is on the front surface of the dial608). This can also be seen inFIG.7(e). The peg820is rotatable within an arc-shaped notch822, which is comprised within the groove818and is limited to +/−60 degrees from the zero position. When the user moves the upper position marker614in order to actuate the dial608from the front, the peg820(at the rear) moves within the notch822and also compresses the spring816. The notch822ensures that the peg820(and thus the upper position marker614) cannot move more than +/−60 degrees. There is a claw824radially inward of the arc-shaped notch822, which is in connection with the peg820and which extends axially rearwards, engaging with the first cog810. The claw824thereby imparts movement to the first cog810when the dial is actuated by the user, via its front surface (for example, via the upper position marker614). For example, the peg820and the claw824may be formed integrally with the so-called ‘cap’ which forms (at least part of) the outer surface of the dial608. For example, they may be injection moulded.

FIG.7(d)shows the cogs810,812, with the potentiometer814. As shown therein, rotational movement of the first cog810will cause rotational movement of the second cog812, which causes movement of the potentiometer. Potentiometer movements can be conveyed by the controller600to the therapeutic radiotherapy device, as control signals for the rotatable gantry or collimator.

As shown inFIG.7(e), there is a so-called ‘rolling bearing’826located between (in an axial or ‘z’ direction) the front surface of the dial608and the first cog810The rolling bearing826is provided to enable smooth rotation of the inner components of the dial, and to increase its durability and performance.

The inner components of the dial, such as the peg820, groove818, and rolling bearing826can be injection moulded from plastic or any other suitable material. This means that they are simple and efficient to manufacture. Alternatively, they may be machined in metallic materials like steel or aluminium alloy.

The inner and outer (or front and rear) components of the dial608combine to form a compact and user-friendly actuator that can be used readily by a user to selectively control a gantry and a collimator on a therapeutic radiotherapy device. The movements required by the user are intuitive and comfortable, and the mechanisms for translating those movements into control signals for the device are streamlined and reliable.

The improved controller600described herein is, both as a whole and when considering its individual component features, highly user-friendly, as it provides the user with a comfortable and intuitive input means, for conveying control instructions to a LINAC or other therapeutic radiotherapy device. Because the user is able to make his or her input movements relative to a zero position, to which the dial608or table controller620is biased, he or she can quickly and easily learn how his or her movements translate to changes in physical attributes of the respective component of the device that is under control. The user therefore quickly learns how big or small an input is needed to change the speed of the relevant component to a desired extent and also how to change the component's rotational or linear (i.e. horizontal and/or vertical) position, by a desired amount. The user can then use this learning to guide subsequent control movements. Moreover, because there are separate actuators for the rotatable aspects of the device and the linearly moveable table, respectively, the risk of user confusion or error is reduced. That is; the controller600embodies the recognition that it is useful to save space by combining certain functions, relating to particular selected features, but that it is useful for other features to be separate therefrom.

The physical motions needed for actuating the most frequently-required actuators, such as the dial608, table controller620, enable bar630and panel shift controls, are comfortable for the user, requiring relatively small movements. Moreover, the movements required are substantially in the same plane as the plane of the user input surface602of the controller600, on which other control means such as buttons will be located and on which the user's thumb would naturally rest when holding the controller600, or on the side of the controller600, where the user will naturally be gripping or cupping the controller600, during use. The user will therefore be able to comfortably move his or her finger or thumb readily between the various actuators on the user input surface602, and between actuating the actuators and merely holding the controller600or resting his or her hand on the surface of the controller600. This is highly advantageous, particularly for users who may be seeing many patients, one after another, and therefore may need to use the controller for long periods of time, and/or repeatedly throughout the day.

By providing this easy-to-learn and intuitive control means, the controller enables the user to make more accurate changes to the speed and positioning of the moving components of the therapeutic radiotherapy device, which will increase the effectiveness of the radiotherapy for treating the patient's target region and help to avoid damage to otherwise healthy tissue and avoid collision between rotational parts and other static objects. It also has the effect of increasing the speed of radiotherapy, thereby improving patient throughput and improving overall experience for individual patients. This could also lead to cost savings, if the device is used more efficiently. The improved controller also increases the speed and facility with which a new or infrequent user of the device can understand, learn and retain how to use it; which limits the risk of user error or inaccuracy and also increases the usefulness of the therapeutic radiotherapy device to the hospital or other facility where it is used, because it makes the device readily useable by a greater number of users.

The control embodies intelligent and efficient recognitions, regarding what functions a user requires from a handheld controller of a Linac device, and which functions are (and are not) likely to be needed simultaneously. This has enabled the controller to be provided in a compact fashion—and to be provided as a single handheld device for controlling operation of a therapeutic radiotherapy device, as opposed to needing multiple handheld devices, as has previously been the case.

User Interface Module (UIM)

It is commonplace to provide a static User Interface Module (UIM) on a Linac or other therapeutic radiotherapy device, to work in conjunction with a set of hand held controllers. In fact, clinical workflows can be done with the hand held controller alone if user prefers to do so. But the UIM can be useful, for example to enable hands free operation if the user needed to use his or her hands temporarily to, for example, adjust the patient's position manually. In some arrangements, the UIM will be configured to provide more finely tuned control of certain components of the device, than the hand held controller would be. However, in some cases—for example when the patient table is at certain positions—the UIM may be difficult or impossible for the user to access, in which case(s) the user could rely solely on the handheld controller, at least temporarily.

In this case, the UIM works in conjunction with a single handheld controller600, which is detailed above. The improved controller600is configured to work in conjunction with a machine-based UIM700, such as the one shown inFIG.6herein.

The UIM700is located on the body of the Linac device—and so will not be moveable. In this arrangement, two identical UIM's700are provided, one either side of the body of the machine (i.e. mirrored about the longitudinal horizontal axis) so that the user may use a UIM700when located on either side of the machine. But in other arrangements, there may be more than two UIM's or just one UIM provided.

The UIM700includes various control buttons. For example, it comprises first702and second704controllers, that can be used to control, respectively, vertical and horizontal movement of the ‘table’ on which a patient is located for radiotherapy. It also provides a table ASU button706, for Automatic Setup of the patient table. It also comprises longitudinal708and lateral710brake releases, for disengaging the corresponding clutches which connect the motor and the driving mechanism and instead enable manual movement of the patient table.

The UIM700also comprises an emergency ‘stop motors’ button712and a motors reset button714.

Generally speaking, the UIM700can be used for initially setting up and moving the patient table, and for emergency measures such as stopping the motors of the device in the event of an emergency. But the UIM is not used for controlling the application of the radiation. This is done by a separate means (see below). A user may choose to use the UIM for configuring the gantry and/or the collimator for the application of radiation for therapeutic radiotherapy. However, when using the UIM the user is obliged to remain at a fixed location, which will not always be possible or helpful.

As discussed in detail above, rather than relying on the UIM at all times, the user may instead choose to use the improved controller600for controlling the rotatable aspects of the Linac's operation—and also for controlling patient table position, and panel position and so on. An advantage of the controller600, over the UIM, is that it enables the user to be generally free to move around, and not to be located at the machine, when radiotherapy is being applied. Because the controller600has been intelligently designed, to provide all the functionality that the user is likely to need during the course of a radiotherapy treatment session, the user would not need to switch between using the handheld controller600and the UIM700. Therefore the controller600provides a very user friendly control means. This has a knock-on effect of providing a more positive patient experience and enabling more efficient and streamline treatment, using the controlled therapeutic radiotherapy device.

There is another physical user interface that interacts with the Linac device, called Function Key Pad (FKP) (not shown in the figures). The FKP is usually located in situ in the control room and is the only place that user can initiate the radiation, for the therapeutic radiotherapy treatment.

Variations

It will be appreciated that the relative location of different features of the user-input surface of the controller can be varied, whilst still providing the control improvements described above in relation to the particular arrangement shown inFIG.5herein. Moreover, the precise number, size, shape and spacing of certain features can be changed. For example, the cross-shaped actuator could be omitted or replaced by a different type of actuator or button, or there could be more than one cross-shaped actuator. Or, for example, the table controller may take a form other than a 4 way slider.

In the arrangement described, the dial is spring biased but any other suitable type of bias may be used, to return the dial to a ‘zero’ or neutral resting position between actuations. Similarly, the resting position of the dial need not be at 12 o'clock or 0°. Similarly, the table controller may be biased in a different manner to the precise form described above in relation toFIG.5. The particular inner (or rear) components of the dial may be varied, as compared to those described above in relation toFIG.7.

Any section headings used herein are merely for organisational purposes. They are not to be construed as limiting or dividing the subject matter disclosed in the application as a whole.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific example implementations, it will be recognized that the disclosure is not limited to the implementations described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.