PATIENT SETUP POSITIONING FOR IRRADIATION TREATMENTS ABSENT FIDUCIAL MARKINGS
TECHNICAL FIELD
The present disclosure generally relates to the field of irradiation treatments and, particularly, to patient registration and platform alignment for an irradiation treatment in the absence of fiducial markings.
BACKGROUND
Teletherapy is defined as a treatment methodology in which an irradiation source is at a distance from a body to be treated. X-rays and electron beams have long been used in teletherapy to treat various cancers. Unfortunately, X-rays exhibit a linear energy transfer approaching an exponential attenuation function and are therefore of minimal safe use for deeply embedded growths. The use of heavy particles, particularly hadrons and more particularly protons, in teletherapy, has found increasing acceptance, due to the ability of heavy particles to penetrate to a specific depth without appreciably harming intervening tissue. In particular, the linear energy transfer of hadrons exhibits an inversed depth profile with a marked Bragg peak defined as the point at which the hadrons deposit most of their energy and occurs at the end of the hadrons path. For electrons, the Bragg peak is not observable due to high scattering. For protons with energies below approximately 70 MeV, scattering considerably supresses the Bragg peak. As a result of this effect, increased energy can be directed at an embedded growth as compared to X-rays and electron beams, which particularly harm intervening tissues. While the term hadrons include a wide range of particles, practically, protons and various ions are most widely used in therapy. For clarity, this document will describe treatment as being accomplished with protons, however this is not meant to be limiting in any way.
The protons or ions can be focused to a target volume of variable penetration depth. In this way the dose profile can be matched closely to the target volume with a high precision. In particular, a proton beam can conform to the shape and depth of a target growth, such as a tumor, so as to avoid irradiating healthy body tissue while delivering a lower total body irradiation dose. As a result, proton therapy can allow for escalated dosages as compared to conventional external beam therapies, which may be particularly beneficial for certain treatments, for example, ocular tumors or skull base and paraspinal tumors. Proton therapy may also enable high precision treatment plans with reduced side effects, such as for pediatric treatments or prostate cancer treatments. In order to ensure complete irradiation of a target growth, a plurality of beams arriving at the embedded growth from several different directions is usually applied. The point at which the plurality of beams intersects, whether they are beamed sequentially or simultaneously, is termed the “isocenter”. To maximize biological effectiveness, the isocenter must be precisely collocated with the target growth.
Irradiation treatment is performed on a target tissue in a well-defined process. During an initial stage, the target tissue is imaged and a treatment plan is established. The treatment plan includes a series of treatment fields, each field defining at least a dosage, a target tissue position and orientation, and irradiation angles, for each irradiation dose. Prior to imaging and treatment planning, the coordinate system of the imaging device is reset in the vicinity of the target tissue, such as by a radiotherapy technologist. Placement or fiducial markers are defined respective of the patient, based on the imaging device initialization coordinates, for guiding patient positioning for the treatment. A plurality of fiducial markings is typically applied, such as markings applied on the patient skin or an affixed accessory, such as a set of three markings to enable three-dimensional (3D) localization. The markings may be formed or highlighted using an indelible mark or a radiopaque material to facilitate their visualization on the imaging device. The markings are usually designed to endure for at least a minimum extent, such as several weeks or months, to last throughout the course of a planned treatment duration. For example, a fiducial marking may be in the form of a dotted ink tattoo. In a subsequent stage, irradiation is performed responsive to the developed treatment plan, at a plurality of treatment sessions over a period of time. During the treatment, care must be taken to ensure proper patient positioning responsive to the fiducial markers, so as to ensure that the applied irradiation doses are properly targeted and to avoid harming organs in the vicinity of the target tissue. Positioning of the patient responsive to the markers is performed based on visualization of the patient in relation to the defined markers. During a treatment session, the patient is brought into an initial setup position by positioning a platform supporting the patient such that the fiducial markers converge with an isocenter of the treatment room. A treatment plan is then executed in relation to this setup position, with the target tissue localized at the treatment room isocenter. The patient is repositioned relative to the setup position in accordance with the treatment plan requirements. Specifically, the target tissue is sequentially repositioned with respect to the beam nozzle of the irradiation beam delivery device, which may have a fixed position or be capable of limited movement, such as by means of a gantry. The treatment room isocenter may be designated by a visual indication, such as a plurality of laser beams. The accuracy of the patient positioning may be verified using image guided radiation therapy (IGRT) techniques. Stabilization mechanisms may be applied to ensure patient positioning is maintained relative to the isocenter during the treatment, such as a mask or shield to affix the face or a body part of the patient.
Besides being time consuming and tedious to apply, fiducial markings may be associated with various complications. Skin markings can be considered unaesthetic and may lead to allergic reactions or skin infections. The enduring and visible nature of the markings can also be detrimental socially or psychologically, for example by serving as a visual reminder of an ailment. Some patients may refuse to undergo markings, for reasons varying from cultural and personal beliefs to cosmetic issues. Certain patients follow religious beliefs that prohibit any form of skin markings or tattoos. Older patients may feel apprehension about skin markings due to societal stereotypes. Other patients may be especially self-conscious, such as young women, and may be opposed to skin markings on aesthetic or cosmetic grounds.
Although most medical practitioners will attempt to avoid marking a patient on conspicuous or clearly exposed body parts, even such attempts may not always be feasible. While it may be possible to have fiducial markings removed, the removal process may be associated with discomfort or bodily disfigurement such as scarring. Furthermore, if the patient is to undergo further irradiation therapy treatment, removal of fiducial markings may inhibit the localization of the previous treatment fields and make positioning of the new treatment fields more difficult. Some fiducial markings may not appear clearly on all skin types. Heavily freckled or dark pigmented skin may hinder the utilization of fiducial skin markings, which may blend in with the skin tone or vanish in a sea of freckles or moles. Rather than utilizing a clearly visible marking, such as a marking based on colored ink, a fiducial marking may alternatively be implemented using a nonvisible substance that does not radiate in the visible light range, such as an ultraviolet (UV) ink that radiates when subject to UV light. However, even nonvisible markings suffer from some of the drawbacks outlined above.
Irradiation treatments are typically administered while the patient is in a lying or recumbent position, where the patient body is aligned substantially horizontal to the ground and supported by an underlying platform surface. For example, a recumbent positioned patient may be in a supine posture, with their back resting against the underlying surface and their face positioned upwards, or in a prone posture, with their chest against the underlying surface and their face pointed downwards. However, certain treatments may be difficult to perform on a horizontally positioned patient, such as due to the location of the growth mass in the body, and such treatments may require or be facilitated by an upright or nonhorizontal positioning. Accordingly, the patient may be situated on a reclining chair that may be repositioned and reoriented along multiple axes in three-dimensional space, e.g., along six degrees of freedom. An upright or seated positioning may also provide greater patient comfort relative to a recumbent positioning, such as for patients suffering from breathing complications. Furthermore, upright positioning may affect changes in the volume, location, and/or motion of body organs, such as the lungs and heart, compared to recumbent positioning, which could have beneficial impacts in certain clinical situations.
Patients treated in a lying position generally remain static, as the irradiation therapy equipment may be repositioned relative to the patient. However, a patient treated while in an upright or non-horizontal position is generally moved over the course of a treatment session, so accurate patient positioning and alignment is particularly important. SUMMARY
In accordance with one aspect of the present disclosure, there is thus provided a method for setting up and positioning a patient for an irradiation treatment absent fiducial markings. The method includes the steps of obtaining platform settings including parameters of a patient support platform for supporting a patient during an irradiation treatment; and obtaining platform location data of the support platform, with the patient absent fiducial markings being mounted on the support platform for imaging, the platform location data including 3D coordinates of the support platform respective of an imager coordinate system of an imager calibrated to a predefined and fixed set of initialization coordinates in the treatment room. The method further includes the steps of imaging a target tissue of the patient on the support platform, using the imager, and generating a treatment plan based on the imaging of the target tissue, the treatment plan including a plurality of treatment fields, each of the treatment fields including treatment angles including at least one platform positioning parameter of the support platform for positioning the patient such that the target tissue is localized at an isocenter of the treatment room. When beginning the irradiation treatment, the method further includes the steps of, mounting the patient absent fiducial markings on the support platform according to the platform settings; and adjusting the support platform to position the patient at a setup position in the treatment room such that the target tissue is localized at an isocenter of the treatment room, according to the treatment plan, the platform location data, and a coordinate system transformation of the imager coordinate system to a room coordinate system of the treatment room. The method may further include determining the coordinate system transformation by: imaging with the imager a dedicated imaging phantom comprising a plurality of markers disposed at known locations in relation to the room coordinate system; identifying the phantom markers in the imaging of the imaging phantom; determining a phantom coordinate system in the imager coordinate system based on the locations of the phantom markers; and determining a transformation of the imager coordinate system to the room coordinate system based on the phantom coordinate system and the known location of the phantom markers in relation to the room coordinate system. The method may further include the step of verifying a positioning of the patient after moving the support platform to position the patient. Verifying a positioning of the patient may include capturing a plurality of orthogonal stereoscopic X-ray images, and adjusting the positioning of the patient in accordance with captured x-ray images. Verifying a positioning of the patient may include imaging the patient to generate a treatment imaging model, identifying discrepancies between the treatment imaging model and a reference imaging model generated from a first imaging, and adjusting the positioning of the patient based on identified discrepancies. The support platform may be adjustable using a platform adjuster, configured to rotate at least one platform surface of the platform about at least one rotational axis, or to displace at least one platform surface of the platform along at least one displacement axis. The patient support platform may include a chair, and the patient may be in a seated position. The irradiation treatment may include a proton irradiation treatment. The step of imaging a target tissue may include sequentially repositioning and reorienting a movable imager in relation to a stationary patient to obtain a plurality of images at multiple imaging angles.
In accordance with another aspect of the present disclosure, there is thus provided a system for setting up and positioning a patient for an irradiation treatment absent fiducial markings. The system includes a processor, configured to obtain platform settings including parameters of a patient support platform for supporting a patient during an irradiation treatment, and to obtain platform location data of the support platform, with the patient absent fiducial markings being mounted on the support platform for imaging, the platform location data comprising 3D coordinates of the support platform respective of an imager coordinate system of an imager calibrated to a predefined and fixed set of initialization coordinates in the treatment room. The system includes an imager, configured to image a target tissue of the patient on the support platform. The processor is further configured to generate a treatment plan based on the imaging of a target tissue, the treatment plan including a plurality of treatment fields, each of the treatment fields including treatment angles including at least one platform positioning parameter of the support platform for positioning the patient such that the target tissue is localized at an isocenter of the treatment room. When beginning the irradiation treatment, the patient absent fiducial markings is mounted on the support platform according to the platform settings, and the processor is configured to direct an adjustment of the support platform to position the patient at a setup position in the treatment room such that the target tissue is localized at an isocenter of the treatment room, according to the treatment plan, the platform location data, and a coordinate system transformation of the imager coordinate system to a room coordinate system of the treatment room. The processor may be configured to determine the coordinate system transformation based on an imaging of a dedicated imaging phantom comprising a plurality of markers disposed at known locations in relation to the room coordinate system, using the imager, by identifying the phantom markers in the imaging of the imaging phantom; determining a phantom coordinate system in the imager coordinate system based on the locations of the phantom markers; and determining a transformation of the imager coordinate system to the room coordinate system based on the phantom coordinate system and the known location of the phantom markers in relation to the room coordinate system. The system may further include a positioning verifier, configured to verify a positioning of the patient after moving the support platform to position the patient. The positioning verifier may include a plurality of X-ray imagers in an orthogonal alignment, and verifying a positioning of the patient may include capturing a plurality of orthogonal stereoscopic X-ray images, and adjusting the positioning of the patient in accordance with captured x-ray images. Verifying a positioning of the patient may include imaging the patient to generate a treatment imaging model, identifying discrepancies between the treatment imaging model and a reference imaging model generated from a first imaging, and adjusting the positioning of the patient based on identified discrepancies. A platform adjuster may be configured to rotate at least one platform surface of the platform about at least one rotational axis, or to displace at least one platform surface of the platform along at least one displacement axis. The imager may include a computed tomography (CT) scanner. The imager may be a movable imager, configured to be sequentially repositioned and reoriented in relation to a stationary patient to obtain a plurality of images at multiple imaging angles. The patient support platform may include a chair, and the patient may be in a seated position. The irradiation treatment may include a proton irradiation treatment. BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Figure 1 is a schematic illustration of an irradiation treatment system, constructed and operative in accordance with an embodiment of the present disclosure;
Figure 2 is a schematic illustration of different coordinate systems for setting up and positioning a patient for an irradiation treatment absent fiducial markings, operative in accordance with an embodiment of the present disclosure; and
Figure 3 is a flow diagram of a method for setting up and positioning a patient for an irradiation treatment absent fiducial markings, operative in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The present disclosure may overcome the disadvantages of the prior art by providing a novel method and system for setting up a patient for an irradiation treatment absent fiducial markings, to enable proper patient positioning for treatment, particularly for an upright alignment, without requiring the prior application of fiducial markings on or around the patient, and without requiring a time-consuming calibration process to ensure proper positioning for different treatment locations, for different patient support platforms, and/or for different subjects.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer and/or section, from another element, component, region, layer and/or section.
It will be understood that when an element is referred to as being “on”, “attached” to, “operatively coupled” to, “operatively linked” to, “operatively engaged” with, “connected” to, “coupled” with, “contacting”, “added to”, etc., another element, it can be directly on, attached to, connected to, operatively coupled to, operatively engaged with, coupled with, added to, and/or contacting the other element or intervening elements can also be present. In contrast, when an element is referred to as being “directly contacting” another element or “directly added” to another element, there are no intervening elements and/or steps present. Whenever the terms “about” or “approximately” is used, it is meant to refer to a measurable value such as an amount, a temporal duration, and the like, and is meant to encompass variations from the specified value, as such variations are appropriate to perform the disclosed methods.
Certain features of the disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.
Whenever terms “plurality” and “a plurality” are used it is meant to include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. The term set when used herein may include one or more items. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.
Throughout, this disclosure mentions “disclosed embodiments”, “disclosed systems” and “disclosed methods”, which refer to examples of inventive ideas, concepts, and/or manifestations described herein. The fact that some disclosed embodiments are described as exhibiting a feature or characteristic does not mean that other disclosed embodiments necessarily share that feature or characteristic.
This disclosure employs open-ended permissive language, indicating for example, that some embodiments “may” employ, involve, or include specific features. The use of the term “may” and other open-ended terminology is intended to indicate that although not every embodiment may employ the specific disclosed feature, at least one embodiment employs the specific disclosed feature. The term “operator” is used herein to refer to any individual person or group of persons operating a method or system according to a disclosed embodiment, such as a medical practitioner involved in performing and/or planning an irradiation treatment procedure (e.g., a radiation oncologist, a radiation therapy nurse, a medical radiation physicist, a radiation therapist, a dosimetrist, and the like).
The terms “subject” and “patient” are used interchangeably herein to refer to an individual upon which a method or system according to a disclosed embodiment is performed, such as a person undergoing an irradiation treatment procedure. The subject may be any living entity, such as a person, human or animal, characterized with body tissue subject to irradiation treatment.
The terms “proton therapy” and “proton treatment” are used interchangeably herein to broadly encompass all forms of particle therapy or hadron therapy that applies beams of energized ionizing particles for radiotherapy purposes, including but not limited to protons, neutrons and other types of ions (all of which are considered encompassed herein by the term “protons”). The terms “irradiation therapy” and “irradiation treatment” as used herein encompasses proton therapy and other treatments involving applied radiation.
The disclosed subject matter will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. For a better understanding of certain embodiments and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.
Reference is now made to Figure 1 , which is a schematic illustration of an irradiation treatment system, generally referenced 110, constructed and operative in accordance with an embodiment of the present disclosure. Treatment system 110 includes an irradiation beam generator 112, an irradiation beam delivery device 114, a primary imager 116, a positioning verifier 117, a processor 118, a database 119, a patient support platform 122, and a platform adjuster 124. Processor 118 is communicatively coupled with beam generator 112, with beam delivery device 114, with imager 116, with positioning verifier 117, with database 119, and with platform adjuster 124. Treatment system 110 is configured to be deployed for treating a patient 120 in a treatment room 100, which is generally characterized with shielding properties to limit radiation from penetrating beyond the treatment area. Some of the components of system 110 may reside outside room 100.
Patient support platform 122 is configured for supporting a patient 120 during a treatment session or planning stage. In one embodiment, patient support platform 122 includes a reclining chair, such that patient 120 may be in a sitting position and supported by a pelvis support member 121 , such as a seat, and a back support member 123, such as a back rest (as illustrated in Fig.1 ). Patient support platform 122 may also include or be converted into a bed, such that patient 120 may be in a lying or recumbent position (i.e. , horizontal to the ground) supported by the bed. Patient support platform 122 is mounted on an adjustable platform base 126, coupled to platform adjuster 124. Pelvis support member 121 may be tilted relative to platform base 126, such as defining an inclination angle (e.g., 10° inclination) relative to a vertical axis. Back support member 123 may be tilted relative to platform base 126, such as defining an inclination angle (e.g., 20° inclination) relative to a horizontal axis.
Platform adjuster 124 is configured to adjust a position and/or orientation of platform 122, so as to correspondingly alter a position and/or orientation of patient 120 along six degrees of freedom (6DOF). Platform adjuster 124 may include a rotational adjustment mechanism, configured to adjust at least one rotational angle of platform 122 (e.g., pitch, yaw, roll rotations), and/or a translational adjustment mechanism, configured to translationally displace platform 122 along at least one axis. For example, platform adjuster 124 may include a first mechanism for adjusting a height of platform base 126, and a second mechanism for rotating platform 122 (e.g., by manipulating an orientation of platform base 126) about pitch, yaw, and roll axes, respectively (e.g., causing patient 120 to lay back, tip sideways, or swivel, respectively). For example, a rotational adjustment mechanism may rotate platform 122 (or platform base 126) about three orthogonal axes 125R, 127R, 129R, where a first axis 125R is parallel to a floor 102 of treatment room 100, a second axis 127R is parallel to floor 102 and orthogonal to first axis 125R, and a third axis 129R is orthogonal to floor 102. The rotation of patient support platform 122 causes a rotation of patient 120 about three orthogonal axes 125P, 127P, 129P, where a first axis 125P is parallel to a longitudinal axis of platform base 126, a second axis 127P is parallel to a longitudinal axis of platform base 126 and orthogonal to first axis 125P, and a third axis 129P is orthogonal to a longitudinal axis of platform base 126. In one embodiment, axes 125P, 127P and 129P correspond to axes 125R, 127R and 129R, respectively.
Irradiation beam generator 112 includes components and techniques for generating an irradiation therapy proton beam, such as a particle accelerator. For example, generator 112 may include a cyclotron or a synchrotron particle accelerator.
Irradiation beam delivery device 114 includes components and techniques for delivering at least one irradiation dose 115 to patient 120 from the generated proton beam. For example, delivery device 114 may operate using a pencil beam scanning (PBS) mechanism. Delivery device 114 may optionally be coupled with a rotatable gantry (not shown), configured for positioning and orienting the beam nozzle about multiple axes in 3D space, for directing a delivered irradiation dose 115 to a selected position and orientation (i.e., a selected isocenter). Alternatively, treatment system 110 may operate without a rotatable gantry, which may provide increased flexibility for treatment of different anatomical sites and may facilitate upright positioning of patient 120.
Imager 116 is configured for imaging patient 120, such as during a treatment planning stage and/or treatment session. For example, imager 116 may be a medical imaging device used in a medical treatment setting, including but not limited to: a computed tomography (CT) imager, a four-dimensional computed tomography (4DCT), an X-ray computed tomography (X-ray CT) scanner, an optical coherence tomography (OCT) scanner, a magnetic resonance imaging (MRI) scanner, and an ultrasound imager. In general, imager 116 may include any type of imaging sensor capable of acquiring and storing an image representation of an object or scene. Accordingly, the term “image” as used herein refers to any form of output from such an imager, including any optical or digital representation of a scene acquired at any wavelength or spectral region, and encompasses both a single image frame and a sequence of image frames (i.e., a “video image”). An image rotation mechanism (not shown) may be configured to rotate imager 116 about at least one axis, to enable imaging from selected directions or viewing angles.
Positioning verifier 117 is configured for verifying that patient 120 is properly positioned in a designated setup position for treatment. Positioning verifier 117 may be embodied, for example, by an X-ray imaging device including a set of complementary X-ray emitter and detector pairings located around a treatment isocenter, where the respective pairings are in perpendicular alignment to one another (i.e. , to enable three-dimensional localization). The X-ray imaging devices may be mounted onto the walls or floor of treatment room 100. Alternative approaches for position verification may include surface guided radiation therapy (SGRT) 3D imaging techniques, and cone beam computed tomography (CBCT) imaging techniques.
Processor 118 is configured to selectively control the operation of components of system 110 and may dynamically adjust operational parameters thereof. Processor 118 is further configured to receive and provide instructions and data from/to components of system 110 and to perform required data processing.
Database 119 stores relevant information to be retrieved and processed by processor 114, such as captured images. Database 119 may be embodied by one or more local servers or by remote and/or distributed servers, such as in a cloud storage platform.
Information may be conveyed between the components of system 110 over any suitable data communication channel or network, using any type of channel or network model and any data transmission protocol (e.g., wired, wireless, radio, WiFi, Bluetooth, and the like). The components and devices of system 110 may be based in hardware, software, or combinations thereof. It is appreciated that the functionality associated with each of the devices or components of system 110 may be distributed among multiple devices or components, which may reside at a single location or at multiple locations. For example, the functionality associated with processor 118 may be distributed between separate components, such as at least one control unit and at least one processing unit (e.g., which may be part of a server or a remote computer system accessible over a communications network, such as a cloud computing platform). Processor 118 may also be at least partially integrated with other components of system 110 (such as incorporated within a dedicated local control unit).
System 110 may optionally include and/or be associated with additional components not shown in Figure 1 , for enabling the implementation of the disclosed subject matter. For example, system 110 may include a user interface (not shown) for allowing a user to provide instructions or control various parameters or settings associated with the components of system 110, and/or a display device (not shown) for visually displaying information relating to the operation of system 110.
An exemplary workflow of an irradiation treatment will now be described in general terms. During an initial session, patient 120 is mounted and positioned on a selected support platform 122, representing a platform on which the irradiation treatment will be performed, i.e. , the same platform or a similar type of platform. An irradiation treatment may be performed on various support platforms, each of which may have adjustable moving parts and accessories. In one embodiment, platform 122 is a reclining chair and patient 120 is supported in an upright or seated position. Parameters or configuration settings of the selected platform 122 are obtained when mounting patient 120 onto platform 122. Platform settings may include a platform type (e.g., type of bed or chair), features (e.g., reclining, non-reclining, maximum reclining angle), dimensions, accessories, default position/orientation, and the like. The platform settings may include how to mount the patient on the platform and which platform accessories should be employed during treatment. For example, certain patients, such as those of a diminutive stature, may be situated on one or more booster seats in order to raise their position upon the platform. Accordingly, the platform settings may include booster seat information, such as: whether a booster seat is applied; type of booster seats; and amount and order of booster seats. Another form of platform accessory may be an armrest, in which case the platform settings may include armrest information, such as: whether an arm rest is utilized; angle at which armrest is aligned; and height at which armrest is attached to the platform. The obtained platform settings are stored, to be applied later when setting up and positioning the respective patient 120 for treatment. Patient 120 is then positioned with respect to imager 116 (e.g., a CT scanner) to allow for imaging of the target tissue via imager 116, such as by moving platform 122 into a field of view of imager 116 and/or adjusting the positioning of patient 120 on platform 122. With the patient 120 properly positioned for imaging, location data of platform 122 is obtained. The platform location data may include 3D position and orientation coordinates of platform 122 in terms of a coordinate system of imager 116. A set of initialization coordinates of imager 116 may be defined, such that imager 116 is calibrated to a zero point in relation to the room, where this point remains fixed during subsequent treatment sessions. The location data may be obtained immediately prior to and/or during the imaging when platform 122 is at the imaging position. Imager 116 then images a target tissue of patient 120 to be treated, such as capturing a plurality of images from multiple imaging angles. In one example, the imaging is performed using a movable imager 116, such as a movable CT imaging device, which is repositioned and reoriented relative to a stationary patient 120 to obtain images from multiple imaging angles. The imaging may take place in treatment room 100 where the treatment will take place, or in a different location, such as an imaging room, which may contain similar system elements as treatment room 100. For example, the imaging room may contain at least one support platform corresponding to and registered with the actual support platform to be used for the patient treatment. The patient imaging may be performed by a first operator, such as a CT imaging technician. In contrast to conventional treatment planning, no fiducial markings are applied on or around patient 120 at this stage.
In a subsequent stage, a treatment plan is established. The treatment planning may be performed by a second operator or a treatment planner, such as a medical physicist. The treatment planning may be performed in the absence of patient 120, at a subsequent date following the patient imaging. The treatment planner receives treatment prescriptions for an irradiation treatment of patient 120. The treatment prescriptions may include details relating to the target tissue (e.g., type, shape, size, location in body), and recommended doses (e.g., recommended minimum and/or maximum doses) to be applied to the target tissue. The treatment planner generates a treatment plan in accordance with the received treatment prescriptions and the imaging of the target tissue (during the earlier imaging session). The treatment plan may include a series of irradiation parameters or “treatment fields” for at least one treatment session, each treatment field defined at least by a dosage, a position and orientation of the target tissue relative to an isocenter, and an irradiation angle, for each irradiation dose. The treatment plan may define a series of treatment angles for directing a respective irradiation dose to the target tissue coordinates. The treatment angles may represent “platform positioning parameters” defining three-dimensional rotations and translations for repositioning the support platform 122 in a 3D coordinate system, such as rotations respective of pitch, yaw and roll axes of platform base 126, and at least one translation of a displacement axis of platform base 126. The treatment planning may utilize a three-dimensional model of the target tissue generated from the captured images. For example, the target tissue model may be a computed tomography (CT) imaging volume. The target tissue imaging volume may be constructed using auxiliary imaging devices, such as stereoscopic imaging.
The generated treatment plan may be verified and updated if needed. A validation of the treatment plan may be performed on site, such as by an operator physically checking and validating the feasibility of treatment plan fields (e.g., doses, patient positioning, treatment angles) at treatment room 100. After the treatment plan has been finalized, the irradiation treatment may be performed over one or more treatment sessions. During a treatment session, the patient 120 is brought to treatment room 100 and mounted onto support platform 122 in accordance with the platform configuration settings obtained during the earlier imaging stage. In particular, patient 120 is mounted and positioned on platform 122 in accordance with the defined features (reclining, non-reclining, maximum reclining angle), dimensions, accessories (e.g., booster seats, armrests), and other relevant parameters of platform 122. Patient 120 is then brought to a setup position for treatment in accordance with the treatment plan. Specifically, platform 122 may be moved such that the target tissue of patient 120 is localized at an isocenter of treatment room 100. The treatment plan may define coordinates of the target tissue, such as in relation to an imager coordinate system respective of imager 116. The patient 120 may be repositioned during a treatment session in accordance with treatment angles defined in the treatment plan. The treatment angles may include a set of platform positioning parameters or inclination angles at which a platform surface 121 , 123 of platform 122 (i.e., pelvis support member 121 and/or back support member 123) is rotated in a 3D angular coordinate system, such as respective of pitch, yaw and roll angular rotations. For example, a “platform yaw angle” defines an angle at which a platform surface 121 , 123 is aligned with respect to an axis orthogonal to floor 102, such as a side to side swiveling rotation (i.e., a yaw rotation); a “platform pitch angle” defines an angle at which a platform surface 121 , 123 is aligned with respect to a transverse axis thereof, such as a forward or backward tilting rotation (i.e., a pitch rotation); and a “platform roll angle” defines an angle at which a platform surface 121 , 123 is aligned with respect to an orthogonal axis thereof, such as a side to side pivoting rotation (i.e., a roll rotation). The platform positioning parameters may further include at least one translational displacement along which platform 122 (or a platform surface 121 , 123) is displaced, such as a height displacement of platform base 126. The treatment angles effectively define a direction vector at which an irradiation beam 115 is directed toward the target tissue coordinates over the course of the treatment session. The target tissue coordinates may be defined in a field of the treatment plan as a point in the imager coordinate system where the target tissue is located. In general, the treatment plan defines a sequence of treatment fields for a respective treatment session. Each treatment field includes an irradiation dose intensity (dosage), an irradiation angle, and a position of the target tissue isocenter, which in turn defines a respective set of treatment angles or platform positioning parameters for directing the irradiation dose to the target tissue according to the respective irradiation angle and respective target tissue coordinates.
Patient 120 is brought into a setup position for treatment, by moving platform 122 within treatment room 100. Platform 122 may be moved or repositioned by means of platform adjuster 124, under limitations or constraints of treatment room 100. For example, platform adjuster 124 may include a robotic arm, which may be configured to selectively modify the direction that a platform surface 121 , 123 is aligned, such as between a right side orientation and a left side orientation. Processor 118 may direct platform adjuster 124 to adjust at least one rotational angle of platform 122 (e.g., pitch, yaw, roll rotations), and/or to translationally displace platform 122 along at least one axis.
The positioning of the patient target tissue to the treatment room isocenter may be performed in accordance with a transformation from an imager coordinate system (coordinate system respective of imager 116) to a room coordinate system (coordinate system respective of treatment room 100), which may be established using suitable processing techniques. Processor 118 may determine treatment angles based on the treatment plan, so as to bring the target tissue coordinates in a required position and orientation in relation to the treatment room isocenter. Reference is made to Figure 2, which is a schematic illustration of different coordinate systems for setting up and positioning a patient for an irradiation treatment absent fiducial markings, operative in accordance with an embodiment of the present disclosure. A first coordinate system 141 is defined with respect to imager 116 and referred to as an “imager coordinate system”. A second coordinate system 142 is defined with respect to treatment room 100 and referred to as a “room coordinate system”. A third coordinate system 143 represents a transformation (e.g., derived using applicable mathematical formulas and/or mapping processes for coordinate transformation) between imager coordinate system 141 and room coordinate system 142, such that each pixel in a target tissue volume (e.g., CT volume) may be addressable to a known physical location in treatment room 100. In one example, transformation 143 is determined by scanning under imager 116 a dedicated imaging phantom in a known location (i.e., position and orientation), such as in relation to treatment room coordinate system 142. The phantom may include a plurality of markers, such as nine metal markers to enable geolocation, disposed at known measurable locations. The phantom is imaged by imager 116 and the resultant images (e.g., CT scan) are processed to identify the phantom markers. A new coordinate system inside imager coordinate system 141 may be constructed according to the phantom markers, and a transformation determined between the newly constructed coordinate system and imager coordinate system 141. The resultant transformation may be combined with the known location of the dedicated imaging phantom in treatment room 100 to obtain a final transformation 143. A patient (not shown) is mounted on support platform 122 and positioned such that coordinates (e.g., a center) of a target tissue is localized at an isocenter 150 of treatment room 100. An irradiation dose may be directed to isocenter 150 by a beam nozzle 134 of an irradiation beam delivery device (not shown). In particular, location data of platform 122 respective of imager coordinate system 141 and obtained during the treatment planning stage, is converted into room coordinate system 142, via transitional imager-to-room coordinate system 143, for bringing the patient in a setup position for treatment. Accordingly, platform 122 is positioned prior to treatment such that a target tissue is localized at treatment room isocenter 150 respective of room coordinate system 142, based on treatment angles extracted from treatment fields of the treatment plan, and based on location data of platform 122 respective of imager coordinate system 141 obtained during treatment planning. The setting up and positioning of the patient for treatment may be performed by a third operator or a treatment practitioner, such as a radiotherapy technologist.
The positioning of the patient 120 to the setup position for treatment may be verified prior to treatment. One approach for verification may include reimaging the patient 120 with imager 116, applying a transform between an imager generated reference model and treatment model, measuring the discrepancies, and applying corrections accordingly. For example, when using a CT scanner imager, positioning registration may be performed by identifying discrepancies between a reference CT volume (on which the treatment plan was based) and a new treatment CT volume (captured during the treatment session) and correcting the discrepancies. Another approach is to bring the patient 120 directly to the room isocenter, and then utilize positioning verifier 117 to verify proper patient positioning. For example, positioning verifier 117 may include complementary X-ray emitter and detector pairings located around the treatment isocenter and in perpendicular alignment, so as to capture at least two X-ray images from orthogonal directions. Based on the captured X-ray images, the positioning of patient 120 may be adjusted in accordance with the required positioning defined by the treatment plan. The operator may receive an alert in the event of an improper and/or proper verification, such as via a visual or audible notification, to indicate when the patient is improperly or properly positioned. After the positioning has been verified, the irradiation treatment may be implemented, over one or more treatment sessions. An irradiation treatment may target different body parts of a patient from different directions or angles. Accordingly, the patient may be positioned on the support platform in different alignments or anatomical positions in relation to the directed irradiation. For example, the irradiation may be directed to the patient anterior (i.e. , such that the back or anterior of the patient is facing a beam nozzle of delivery device 114), or to the patient posterior (e.g., such that the front or posterior of the patient is facing a beam nozzle of delivery device 114).
It will be appreciated that the disclosed embodiments may allow for setting up and positioning a patient for an irradiation treatment without prior application of fiducial markings. The disclosed embodiments may allow an operator to accurately position and verify the correct positioning of the patient, in accordance with an established treatment plan, while avoiding the need to apply fiducial markings on the patient during an initial session. In this manner, potential complications associated with fiducial markings can be avoided, such as allergic reactions, skin infections, aesthetic or cosmetic concerns, patient reservations, difficulties in perceiving the markings, and byproducts of marking removal. The time-consuming and tedious process of applying the markings can also be averted. It is further appreciated that the disclosed embodiments may provide for patient positioning absent fiducial markings for patient irradiation treatment in an upright or non-horizontal (e.g., seated) position.
Reference is made to Figure 3, which is a flow diagram of a method for setting up and positioning a patient for an irradiation treatment absent fiducial markings, operative in accordance with an embodiment of the present disclosure. In a step 172, platform settings of a support platform for supporting a patient for an irradiation treatment is obtained. Referring to Figure 1 , processor 118 receives platform configuration settings including parameters of support platform 122 for supporting patient 120 during an irradiation treatment. The platform settings may include parameters relating to: platform type, platform features (e.g., reclining, non-reclining, maximum reclining angle), a default position and orientation; platform dimensions; platform accessories (e.g., booster seats, armrests); and how to mount patient 120 on platform 122. In a step 174, platform location data of the support platform is obtained, with the patient absent fiducial markings being mounted on the platform for imaging. Referring to Figures 1 and 2, processor 118 receives platform location data of platform 122 with patient 120 mounted on platform 122 absent fiducial markings and positioned for imaging of a target tissue by imager 116. The platform location data may include 3D coordinates (position and orientation) of platform 122 with respect to an imager coordinate system 141 of imager 116, which is calibrated to a predefined and fixed set of initialization (zero point) coordinates in room 100. The platform location data may further include an alignment of patient 120 with respect to platform 122, such as depending on the type of treatment or location of target tissue.
In a step 176, a target tissue of the patient on the support platform is imaged. Referring to Figure 1 , imager 116 images a target tissue of patient 120 while patient is supported on platform 122 in an imaging position and alignment. For example, imager 116 captures a plurality of images from a plurality of imaging angles, from which a target tissue imaging volume may be generated. The imaging may be performed using a movable imager 116, such as a movable CT imaging device, which is repositioned and reoriented relative to a stationary patient 120.
In a step 178, a treatment plan is generated based on the imaging. In particular, a treatment planner receives treatment prescriptions for an irradiation treatment of patient 120, such as target tissue characteristics and recommended doses to be applied to the target tissue, and generates a treatment plan based on the treatment prescriptions and the target tissue imaging. The treatment plan may include a sequence of treatment fields for at least one treatment session. Each treatment field may include at least an irradiation dose intensity (dosage), target tissue coordinates, and an irradiation angle for each irradiation dose. The treatment plan may define a series of treatment angles for directing a respective irradiation dose to the target tissue according to a respective irradiation angle. The treatment angles may include platform positioning parameters defining a set of rotational angles and translational displacements in a 3D angular coordinate system, for rotating and displacing at least one platform surface 121 , 123 of platform 122. It is noted that steps 172, 174, 176 and 178 may be performed during a pre-treatment stage of the irradiation treatment.
In a step 180, the patient absent fiducial markings is mounted on the support platform according to the platform settings. Referring to Figure 1 , patient 120 is brought to treatment room 100 during a treatment session and mounted onto support platform 122, where patient 120 is without fiducial markings, in accordance with the platform configuration settings (as obtained in step 172).
In a step 182, the platform is adjusted to position the patient at a setup position in the treatment room, according to the treatment plan, the platform location data, and a coordinate system transformation of an imager coordinate system to a treatment room coordinate system. Referring to Figures 1 and 2, an operator (i.e., a treatment practitioner) brings patient 120 to a setup position in treatment room 100, such that an isocenter of the target tissue is localized at an isocenter of treatment room 100, according to the treatment plan (generated in step 178) and the location data of platform 122 (obtained in step 174). Patient 120 may be brought into the setup position for treatment by adjusting platform 122 using platform adjuster 124. In particular, platform adjuster 124 may adjust a position and orientation of platform 122, in accordance with defined treatment angles of a respective treatment field of the treatment plan, such as by applying pitch, yaw, and roll angular rotations of a platform surface 121 , 123 of platform 122, and/or by applying at least one translational displacement, so as to position platform 122 at the defined treatment angles. The positioning of the target tissue relative to the room isocenter 150 may be performed according to a transformation from an imager coordinate system 141 (respective of imager 116) to a room coordinate system 143 (respective of treatment room 100), via a transformational coordinate system 143. In particular, platform 122 is positioned such that the target tissue is localized at treatment room isocenter 150 respective of room coordinate system 142, based on treatment angles extracted from a treatment field of the treatment plan, and based on location data of platform 122 respective of imager coordinate system 141. According to one embodiment, patient 120 is positioned on platform 122 in an upright or seated position. The coordinate system transformation 143 may be determined previously using an imaging phantom. In particular, a dedicated imaging phantom including a plurality of markers (e.g., nine markers) disposed at known locations in relation to room coordinate system 142 is imaged using imager 116. The phantom markers are identified in the images, and a phantom coordinate system in the imager coordinate system is established based on the known locations of the phantom markers. A transformation 143 of imager coordinate system 141 to room coordinate system 142 is then established based on the phantom coordinate system and the known location of the phantom markers in relation to room coordinate system 142.
In a step 184, the patient positioning is verified. Referring to Figure 1 , an operator verifies that the patient is properly positioned in the setup position for treatment, such as by using positioning verifier 117. For example, positioning verifier 117 may capture a plurality of X-ray images from orthogonal directions, and the positioning of patient 120 may be adjusted based on the captured X-ray images to ensure proper positioning in accordance with the treatment angles of the respective treatment field of the treatment plan. Alternatively, the operator may verify the patient positioning by reimaging patient 120 with imager 116, identifying discrepancies between an imager reference model (e.g., a reference CT volume on which the treatment plan was based) and a newly acquired treatment CT volume, and correcting the positioning as needed based on the identified discrepancies. Stabilization mechanisms may be applied to ensure patient positioning is maintained relative to the isocenter during the treatment, such as a mask or shield to affix the face and/or other body parts of patient 120.
In a step 186, an irradiation treatment is performed after the patient positioning is verified. Referring to Figure 1 , patient 120 is subject to at least one irradiation dose of an irradiation treatment during a treatment session, in accordance with a sequence of treatment fields of the generated treatment plan. The irradiation treatment may target at least one body part of patient 120 and may be directed toward an anterior or posterior of patient 120. An auxiliary imaging may be applied (such as using positioning verifier 117) during the treatment application session, to ensure that the characteristics of the target tissue has not changed significantly since the onset of treatment (which may require modifications to the treatment plan).
In a step 188, the irradiation treatment session is terminated. Referring to Figure 1 , the operator ends the treatment session, following the application of a final irradiation dose to patient 120 according to a final treatment field of the generated treatment plan for the respective session. The irradiation treatment for patient 120 may continue during subsequent treatment sessions. Steps 180, 182, 184, 186 and 188 may be performed during a treatment stage of the irradiation treatment.
While certain embodiments of the present disclosure have been described, so as to enable one of skill in the art to practice the disclosed subject matter, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the disclosed subject matter, which should be determined by reference to the following claims.