Abstract:
A system, method, apparatus, and means for controlling a portal imager includes operating a radiation therapy device to identify segment data defining a radiation therapy segment, identifying (from the segment data) portal position information, and positioning a portal imaging device based on the portal position information. The radiation therapy device may be further operated to identify field information identifying a radiation field to be delivered, position elements of the radiation therapy device to deliver the field, deliver the field, and capture a portal image on the portal imaging device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to commonly owned U.S. patent application Ser. No. 09/909,589, filed Jul. 20, 2001, for “AUTOMATED DELIVERY OF TREATMENT FIELDS” the contents of which is incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to radiation therapy devices, and more particularly, to the automated delivery and monitoring of radiation therapy. 
     2. Description of the Related Art 
     Conventional radiation therapy typically involves directing a radiation beam at a tumor in a patient to deliver a predetermined dose of therapeutic radiation to the tumor according to an established treatment plan. This is typically accomplished using a radiation therapy device such as the device described in U.S. Pat. No. 5,668,847 issued Sep. 16, 1997 to Hernandez, the contents of which are incorporated herein for all purposes. 
     The radiotherapy treatment of tumors involves three-dimensional treatment volumes which typically include segments of normal, healthy tissue and organs. Healthy tissue and organs are often in the treatment path of the radiation beam. This complicates treatment, because the healthy tissue and organs must be taken into account when delivering a dose of radiation to the tumor. While there is a need to minimize damage to healthy tissue and organs, there is an equally important need to ensure that the tumor receives an adequately high dose of radiation. Cure rates for many tumors are a sensitive function of the dose they receive. Therefore, it is important to closely match the radiation beam&#39;s shape and effects with the shape and volume of the tumor being treated. It is also important to properly position the patient on the treatment table to avoid damaging tissue and critical organs. 
     Portal imaging techniques have been developed to assist in positioning patients, and in verifying the shape of a field delivered to a treatment area on the patient. Most portal imaging techniques utilize photographic films which are carefully positioned by an operator by hand. Because most radiation therapy devices are located within vaults constructed with thick concrete walls and thick doors which can take 30 seconds to open and close, it can take a significant amount of time for an operator to position the film, leave the room, operate the radiation therapy device to deliver radiation, and enter the room to remove the film with the captured portal image. 
     Electronic portal imaging techniques have also been used which avoid the need to switch films to take multiple images and which eliminates the need to process and expose films to view a portal image. Such electronic techniques, however, still require manual intervention by an operator to configure and manipulate the portal imager, by entering the treatment room. It would be desirable to provide a portal imaging approach which reduces or eliminates the amount of manual intervention required. It would further be desirable to provide a portal imaging approach which integrates control of the portal imager with operation of the radiation therapy device. 
     SUMMARY OF THE INVENTION 
     According to one embodiment of the present invention, a system, method, apparatus, and means for controlling a portal imager includes operating a radiation therapy device to identify segment data defining a radiation therapy segment, identifying (from the segment data) portal position information, and positioning a portal imaging device based on the portal position information. The radiation therapy device may be further operated to identify field information identifying a radiation field to be delivered, position elements of the radiation therapy device to deliver the field, deliver the field, and capture a portal image on the portal imaging device. 
     In some embodiments, the portal imaging device is a flat panel detector movably coupled to a gantry of the radiation therapy device. In some embodiments, the portal imaging device is positioned using a drive motor controlled by control signals received from an operators console. In some embodiments, the portal imaging device may be positioned a number of times during a treatment based on position information for each segment of the treatment. 
     The present invention is not limited to the disclosed preferred embodiments, however, as those skilled in the art can readily adapt the teachings of the present invention to create other embodiments and applications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exact nature of this invention, as well as its objects and advantages, will become readily apparent from consideration of the following specification as illustrated in the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and wherein: 
     FIG. 1 is diagram illustrating a radiation therapy device including a portal imaging device pursuant to some embodiments of the present invention; 
     FIG. 2 is a block diagram illustrating portions of the radiation therapy device of FIG. 1 according to some embodiment of the present invention; 
     FIG. 3 is a side view of the radiation therapy device of FIG. 1 showing a retracted portal imaging device; 
     FIG. 4 is a side view of the radiation therapy device of FIG. 1 showing an extended portal imaging device; and 
     FIG. 5 is a flow diagram illustrating a process for the control of a portal imaging device of FIG. 1 according to some embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor for carrying out the invention. Various modifications, however, will remain readily apparent to those skilled in the art. 
     Turning now to the drawings and, with particular attention to FIG. 1, a radiation therapy device  10  pursuant to embodiments of the present invention is shown. According to one embodiment of the present invention, radiation therapy device  10  includes a beam shielding device (not shown) within a treatment head  24 , a control unit in a housing  30  and a treatment unit  32 . An accessory tray  25  is mounted to an exterior of treatment head  24 . Accessory tray  25 , in one embodiment, is configured to receive and securely hold attachments used during the course of treatment planning and treatment (such as, for example, reticles, wedges, or the like). 
     Radiation therapy device  10  includes a gantry  26  which can be swiveled around a horizontal axis of rotation  20  in the course of a therapeutic treatment. Treatment head  24  is fastened to a projection of the gantry  26 . A linear accelerator (not shown) is located inside gantry  26  to generate the high energy radiation required for the therapy. The axis of the radiation bundle emitted from the linear accelerator and the gantry  26  is designated by beam path  12 . Electron, photon or any other detectable radiation can be used for the therapy. 
     Radiation therapy device  10  also includes a central treatment processing or control unit  32  which is typically located apart from radiation therapy device  10 . Radiation therapy device  10  is normally located in a different room to protect the therapist from radiation. For example, radiation therapy device  10  may be located in a heavily shielded room, such as a concrete vault, which shields the operator from dangerous megavoltage ionizing radiation generated by radiation therapy device  10 . 
     Treatment unit  32  includes a processor  40  in communication with an operator console  42  (including one or more visual display units or monitor) and an input device such as a keyboard  44 . Data can be input also through data carriers such as data storage devices or a verification and recording or automatic setup system. More than one control unit  32 , processor  40 , and/or operator console  42  may be provided to control radiation therapy device  10 . 
     Treatment processing unit  32  is typically operated by a therapist who administers actual delivery of radiation treatment as prescribed by an oncologist. Therapist operates treatment processing unit  32  by using keyboard  44  or other input device. The therapist enters data defining the radiation dose to be delivered to the patient, for example, according to the prescription of the oncologist. The program can also be input via another input device, such as a data storage device. Various data can be displayed before and during the treatment on the screen of operator console  42 . 
     During a course of treatment, the radiation beam is trained on treatment zone  18  of an object  22 , for example, a patient who is to be treated and whose tumor lies at the isocenter of the gantry rotation. The plates or leaves of the beam shielding device within the treatment head  24  are substantially impervious to the emitted radiation. The collimator leaves or plates are mounted between the radiation source and the patient in order to delimit (conform) the field. Areas of the body, for example, healthy tissue, are therefore subject to as little radiation as possible and preferably to none at all. The plates or leaves are movable such that the distribution of radiation over the field need not be uniform (one region can be given a higher dose than another). Furthermore, the gantry can be rotated so as to allow different beam angles and radiation distributions without having to move the patient. 
     According to embodiments of the present invention, radiation therapy device  10  includes an imaging device  34  which is used, as will be described further below, to perform portal imaging for radiation therapy treatments. Imaging device  34  may be attached to gantry  26  via an extendible and retractable arm structure  35 . Pursuant to embodiments of the present invention, imaging device  34  may be advanced to, and retracted from, an imaging position along beam path  12 . 
     Control of imaging device  34  is integrated with operation of other components of radiation therapy device  10 . For example, data defining a prescribed course of treatment which is stored at, or otherwise accessible to, computer  40 , may include data which manipulates elements of radiation therapy device  10  to deliver a prescribed course of radiation and it may also include data which causes imaging device  34  to be extended, retracted, and otherwise manipulated to capture portal images. 
     Pursuant to embodiments of the present invention, this integrated control allows portal images to be captured without requiring manual intervention by an operator, and further, without requiring the operator to enter the room to manipulate controls of the imaging device. Accuracy and control of treatments and capture of portal images are believed to be improved because the control is integrated with control of other elements of radiation therapy device  10 . 
     Imaging device  34 , in one embodiment, is a flat panel imaging device using solid state amorphous silicon sensors. The RID 1640, offered by PerkinElmer®, Inc. of Fremont Calif. is one suitable device. In one embodiment, the imaging device used as imaging device  34  is formed with a plurality of detector elements formed in a two dimensional array. In one embodiment, each detector element (or “pixel”) in the array is a solid state sensor, such as a solid state amorphous silicon sensor. Operation of imaging device  34  may result in the capture of a two dimensional image. In one embodiment, computer  40 , in conjunction with control electronics which will be described further below, operate to control imaging device  34  to capture an image and map the signal detected by each of the detector elements to a gray scale value, providing a graphical depiction of the captured image. 
     Imaging device  34  may be attached to gantry  26  via arm structure  35  or in some other manner which allows it to be adjustably placed under patient  22  and along beam path  12 . In some embodiments, imaging device  34  has sufficient sensitivity and dynamic range to allow it to take portal images for different types of radiation (e.g., including electron, photon, and mixed beams). In some embodiments, imaging device  34  is used to verify the shape and intensity of fields during the course of a treatment as well as to verify the position of the patient and the field. In some embodiments, imaging device  34  is used to take pre- or post-treatment portal images, in others, it is used to take portal images during treatment. According to some embodiments, imaging information captured by imaging device  34  is transmitted to treatment processing unit  32 , allowing the radiation therapist to make any necessary beam or positioning adjustments. 
     Referring now to FIG. 2, a block diagram is shown depicting portions of a radiation therapy device  10  and treatment unit  32  according to one embodiment of the present invention. In particular, treatment delivery elements of a radiation therapy device are shown, which may be configured in radiation therapy device  10  and treatment unit  32  as depicted in FIG.  1 . The treatment delivery elements include a computer  40 , operatively coupled to an operator console  42  for receiving operator control inputs and for displaying treatment data to an operator. 
     Operator console  42  is typically operated by a radiation therapist who administers the delivery of a radiation treatment as prescribed by an oncologist. Using operator console  42 , the radiation therapist enters data that defines the radiation to be delivered to a patient. The radiation therapist also enters data that defines the capture of portal images during the course of a treatment plan. As used herein, an overall treatment for a patient may be broken into a number of different “segments”, each having one or more “port” position of the gantry. The radiation therapist may enter data defining one or more ports at which a portal image is to be taken using imaging device  34 . Data defining the different portal images to be taken during a treatment is integrated with other data defining actions to be taken during a particular segment (e.g., such as the radiation to be delivered to the patient and the shape of the field to be used at each port). As a result, control of imaging device  34  is integrated with control of other elements of radiation therapy device  10 . 
     Mass storage device  46  stores data used and generated during the operation of the radiation therapy device including, for example, treatment data as defined by an oncologist for a particular patient. This treatment data is generated, for example, using a treatment planning system  60  which may include manual and computerized inputs to determine a beam shape prior to treatment of a patient. Treatment planning system  60  is typically used to define and simulate a beam shape required to deliver an appropriate therapeutic dose of radiation to treatment zone  18 . 
     Data defining the beam shape and treatment are stored, e.g., in mass storage device  46  for use by computer  40  in delivering treatment. Data defining positioning of imaging device  34  are also stored in, or accessible to, mass storage device  46  for use by computer  40  in delivering treatment. According to some embodiments of the present invention, treatment planning may include activities which occur prior to the delivery of the treatment, such as the generation of treatment data defining a photon treatment, an electron treatment, and/or a mixed beam treatment. 
     Mass storage device  46  may also store other information and programs used to operate radiation therapy device  10 . For example, mass storage device  46  may store one or more interlock libraries, each defining one or more interlocks to be used in the operation of radiation therapy device  10  in a particular operation mode (e.g., different interlocks may be used depending on whether the treatment uses primary electrons, primary photons, or mixture of primary electrons and primary photons). One or more interlock libraries defining permitted positions of imaging device  34  may also be generated (e.g., extension of imaging device  34  may be prevented when the extension would interfere with a particular patient or table position). 
     Although a single computer  40  is depicted in FIG. 2, those skilled in the art will appreciate that the functions described herein may be accomplished using one or more computing devices operating together or independently. Those skilled in the art will also appreciate that any suitable general purpose or specially programmed computer may be used to achieve the functionality described herein. 
     Computer  40  is also operatively coupled to various control units including, for example, a gantry control  44  and a table control  48 . In operation, computer  40  directs the movement of gantry  26  via gantry control  44  and the movement of table  16  via table control  48 . These devices are controlled by computer  40  to place a patient in a proper position to receive treatment from the radiation therapy device. In some embodiments, gantry  26  and/or table  16  may be repositioned during treatment to deliver a prescribed dose of radiation. 
     According to some embodiments of the present invention, computer  40  is operatively coupled to a imaging device control  49 . Imaging device control  49  is used to control the operation of imaging device  34  to perform treatment field verifications and to capture portal images pursuant to embodiments of the present invention. Embodiments of the present invention permit the integrated control and capture of portal images in conjunction with radiation therapy. Imaging device control  49  may also be used to control the positioning of imaging device  34 . In some embodiments, gantry control  44  may be used to control the positioning of imaging device  34 . In particular, imaging device control  49  (or gantry control  44 ) may be used to control the operation of imaging device drive  47  which is manipulated to extend and retract imaging device  34  as desired. 
     According to one embodiment of the present invention, computer  40  and imaging device control  49  perform processing to enhance or manipulate the image captured by imaging device  34  (e.g., as described in the co-pending U.S. Patent Application for “VERIFICATION OF TREATMENT FIELDS” referred to above). As a result, processing performed by computer  40  and imaging device control  49  may be used to generate a portal image depicting the patient anatomy and the photon or electron collimator field edge. 
     Computer  40  is also operatively coupled to a dose control unit  50  which includes a dosimetry controller and which is designed to control a beam source  52  to generate a desired beam achieving desired isodose curves. Beam source  52  may be one or more of, for example, an electron, and/or photon beam source. Beam source  52  may be used to generate radiation beams in any of a number of ways well-known to those skilled in the art. For example, beam source  52  may include a dose control unit  50  used to control a trigger system generating injector trigger signals fed to an electron gun in a linear accelerator (not shown) to produce en electron beam as output. Beam source  52  is typically used to generate a beam of therapeutic radiation directed along an axis (as shown in FIG. 1 as item  12 ) toward treatment zone  18  on patient  22 . 
     According to one embodiment of the invention, the beam generated by beam source  52  is shaped using one or more collimators  62 . Collimator  62  is manipulated by collimator control  54  utilizing sensor(s)  56  and drive unit  58 . 
     Referring now to FIG. 3, a side view of portions of radiation therapy device  10  is shown. In particular, FIG. 3 depicts a view of radiation therapy device  10  in which imaging device  34  is in a retracted position (e.g., moved out of beam path  12  and secured to a housing of gantry  26 ). In this position, gantry  26  may be freely rotated about axis  20  to direct a beam of therapeutic radiation along beam axis  12  toward a treatment zone  18  without interference from imaging device  34 . Further, in this retracted position, sensitive electronics within imaging device  34  may be protected from irradiation. 
     Referring now to FIG. 4, a further side view of portions of radiation therapy device  10  is shown. In this view, imaging device  34  is extended in an imaging position along beam path  12 . That is, in this position, imaging device  34  may be operated to capture one or more portal images. Positioning of imaging device  34  between the retracted and extended positions is performed under the control of computer  40  manipulating imaging device drive  47  via imaging device control  49  or gantry control  44  (FIG.  2 ). Further, in some embodiments, positioning of imaging device  34  is integrated with the overall operation of radiation therapy device  10  to delivery a prescribed course of treatment. As a result, portal images may be taken at various points during a treatment, allowing a radiation therapist to verify the field shape and patient position without need for the therapist to enter the treatment room or manually position or adjust the imaging device. 
     Referring now to FIG. 5, a flow diagram is shown depicting one embodiment of an automated process  100  for capturing portal images during operation of a radiation therapy device. This processing may be performed under the control of computer program code stored at, or accessible by, computer  40  of treatment processing unit  32 . The particular arrangement of elements in the flow chart of FIG. 5 is not meant to imply a fixed order to the steps; embodiments of the present invention can be practiced in any order that is practicable. 
     Processing begins at  102  where equipment, including radiation therapy device  10  and treatment processing unit  32 , are powered on or otherwise enabled for use. Processing continues at  104  where port and segment data is retrieved. According to one embodiment, treatment processing unit  32  may store one or more courses of treatment prescribed for patients by oncologists. These courses of treatment may be stored as one or more treatment segments or groups associated with each patient. This information may be stored at, or accessible to, computer  40 . 
     Processing at  104  may involve data entry by a radiation therapist operating operator console  42  to select a particular segment. In some embodiments, a particular segment is selected by computer  40  once patient information has been selected or entered. According to embodiments of the present invention, each segment may define a particular radiation therapy to be delivered (e.g., a defined shape and dose of primary electrons, primary photons, or a mixture of both), as well as one or more portal images to be captured within the segment. 
     Processing continues at  106  where appropriate libraries are retrieved or otherwise identified. Mass storage device  46  (or other devices in communication with computer  40 ) may store or have accessible to it, one or more interlock, or safety libraries which define permissible control sequences for each treatment type (e.g., different interlocks may be defined for primary photon fields that for primary electron fields) and for each port position. Other libraries and/or data files may also be retrieved at  106 , including, for example configuration files defining one or more configurable features of components of radiation therapy device  10 . In one embodiment, appropriate libraries and other data files are selected at  106  based on the particular segment retrieved at  104 . These libraries will be used to configure and control components of radiation therapy device  10  during delivery of each field of the segment, including the positioning and operation of imaging device  34 . 
     Processing continues at  108  where particular segment data from the data retrieved at  104  is loaded for processing. Each segment may include one or more individual instructions, each defining radiation fields to be delivered by radiation therapy device  10 , as well as one or more imaging device positions to be adjusted for each field. Each instruction may be separately parsed by computer  40  and used to position components of radiation therapy device  10  to deliver the prescribed field and to capture a desired portal image. At  108 , the instruction is loaded for processing. 
     Processing continues at  110  where a determination is made whether the segment data loaded at  108  requires the operating of imaging device  34  to perform imaging. Some fields or segments may not require any positioning of imaging device  34  (i.e., the imaging device may remain in the retracted position). Other fields may require the capture of one or more images requiring the positioning of imaging device  34  in the extended position. 
     If processing at  110  indicates that no image is to be taken, processing continues at  112  where the segment data loaded at  108  is used to configure radiation therapy device  10  and to operate radiation therapy device to deliver a prescribed dose of therapeutic radiation. Processing continues to  116  where a determination is made whether the therapy includes further segment data (e.g., defining further fields to be delivered). If further segment data is included in the therapy, processing reverts back to  108  where the next segment data is loaded for processing. If processing at  1   16  indicates that no further segments are included in the therapy, processing completes. 
     If processing at  110  indicates that imaging is required, processing continues to  118  where the segment data loaded at  108  is used to direct the positioning of imaging device  34 . This positioning may be performed under the control of imaging device control  49  or gantry control  44  operating one or more imaging device drives  47  to position imaging device  34 . For example, imaging device drive  47  may be operated to extend imaging device  34  to a position along beam path  12  (FIG.  4 ). At  120  (which may be an optional step) processing includes verifying that the imaging device is in the desired position. This verification may be performed by detecting control signals from imaging device drive  47  or from one or more sensors positioned to verify the position of imaging device  34 . 
     Processing continues at  124  where a determination is made whether the image to be captured is a post-treatment image. If it is, processing continues at  126  where the segment data loaded at  108  is used to configure radiation therapy device  10  and to operate radiation therapy device to deliver a prescribed dose of therapeutic radiation. After delivery of the radiation, processing continues at  128  where a dose of radiation necessary for an image is generated while imaging device  34  is operated to capture a portal image. The portal image captured at  128  may be transmitted to computer  40  for processing. Processing continues to  116  where a determination is made whether the therapy includes further segment data (e.g., defining further fields to be delivered). 
     If processing at  124  indicated that the image to be taken is not a post-treatment image, processing continues to  130  where a determination is made whether the image to be captured is a pre-treatment image. If so, processing continues to  132  where a dose of radiation necessary for an image is generated while imaging device  34  is operated to capture a portal image. The portal image may be transmitted to computer  40  for manipulation and further processing. Processing continues at  134  where the segment data loaded at  108  is used to configure radiation therapy device  10  and to operate radiation therapy device to deliver a prescribed dose of therapeutic radiation. Processing continues to  136  where a determination is made whether the therapy includes further segment data (e.g., defining further fields to be delivered). If further segment data is provided, processing reverts to  108  where the next segment data is loaded and the process repeats. Otherwise, processing completes. 
     If processing at  130  indicated that the image to be taken is not a pre-treatment image, processing continues to  138  where the segment data loaded at  108  is used to configure radiation therapy device  10  to prepare for delivery of a therapeutic dose of radiation. Processing continues at  140  where segment data loaded at  108  is used to operate radiation therapy device  10  while simultaneously operating imaging device  34  to capture one or more portal images during delivery of the radiation. Again, the captured image(s) may be transmitted to computer  40  for further processing and analysis. Processing continues to  116  where a determination is made whether the therapy includes further segment data (e.g., defining further fields to be delivered). If further segment data is provided, processing reverts to  108  where the next segment data is loaded and the process repeats. Otherwise, processing completes. 
     Although the above process has been described as a single process which allows integrated control and use of imaging device  34  to take pre-post- and mid-treatment portal images, those skilled in the art will recognize that the processing of FIG. 5 may be broken into discrete subcomponents which are followed based on an overall treatment plan. Images captured by imaging device  34  may be manipulated and viewed by an operator or oncologist to adjust future treatments, adjust device settings, or take other corrective actions. In some embodiments, image processing techniques may be used by computer  40  to manipulate the images captured. 
     Those skilled in the art will appreciate that various adaptations and modifications of the just described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.