This invention relates to the field of radiation treatment delivery systems and, in particular, to systems and methods for radiation detection.
In radiosurgery or radiotherapy (collectively referred to as radiation treatment) very intense and precisely collimated doses of radiation are delivered to a target region in the body of a patient in order to treat or destroy lesions. Typically, the target region consists of a volume of tumorous tissue. Radiation treatment requires an extremely accurate spatial localization of the targeted lesions. Radiation treatment offers apparent advantages over conventional surgery, during which a surgeon's scalpel removes the lesion, by avoiding the common risks and problems associated with open surgery. These problems include invasiveness, high costs, the need for in-hospital stays and general anesthesia, and complications associated with post-operative recovery. When a lesion is located close to critical organs, nerves, or arteries, the risks of conventional surgery are even greater.
Radiation treatment requires a high precision diagnosis and high precision radiation source control. Quality assurance mechanisms are used prior to and, sometimes, during treatment to ensure proper alignment and configuration of the system prior to and during delivery of a prescribed radiation dose to a patient. One such quality assurance mechanism is an iso-post which is typically located near the center of the imaging system. The iso-post 10, as shown in
The iso-crystal 12, shown in more detail in
It is also desirable for the iso-crystal 12 to have a spherical shape; however, it is difficult to mold the glue and bead mixture to have a spherical shape—the resulting iso-crystal 12 often has a tear-drop shape.
In addition, the gathering angle α of the fiber 14 is limited in the illustrated design because the iso-crystal 12 must be formed around the end of the fiber 14. The gathering angle α of the fiber 14 of the prior art design is typically at most 60°.
In conventional systems, if the iso-crystal or detector needs to be replaced, the entire iso-post typically must be replaced. It is also difficult to create multiple, uniform iso-crystals. Thus, the entire radiation system may need to be recalibrated when the iso-post is replaced. In addition, the limited gathering angle of the iso-crystal limits the amount and location of radiation that can be detected.
The invention is described by way of example with reference to the accompanying drawings, wherein:
Embodiments of systems, devices and methods for radiation treatment are described herein. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places through this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
A light gathering apparatus for radiation treatment is disclosed herein. The light gathering apparatus may include a light gathering element having an outer surface, a portion of the outer surface of the light gathering element being substantially omni-directional. A portion of the outer surface of light gathering element is coupled to an optical fiber at substantially the base of the optical fiber. The light gathering apparatus may also include a cartridge having an opening therein for receiving the optical fiber, the light gathering element positioned at an end of the cartridge. A detector, coupled with the optical fiber, may be in the cartridge.
System 100 may be used to perform radiotherapy or radiosurgery to treat or destroy lesions within a patient. During radiation treatment, the patient rests on treatment couch 110, which is maneuvered to position a volume of interest (“VOI”) within a patient to a preset position or within an operating range accessible to radiation treatment source 102 (e.g., field of view). Similarly, radiation treatment source 102 is maneuvered with multiple degrees of freedom (e.g., rotational and translation freedom) to one or more locations during delivery of a treatment plan. At each location, radiation treatment source 102 may deliver a dose of radiation as prescribed by a treatment plan.
Imaging sources 108 and imaging detectors 106 are part of an image guidance system that provides control over the position of treatment couch 110 and/or radiation treatment source 102 to position and align radiation treatment source 102 with the target VOI within the patient.
In one embodiment, radiation treatment delivery system 100 may be an image-guided, robotic-based radiation treatment system such as the CyberKnife® system developed by Accuray, Inc. in California. In
Imaging sources 108A and 108B and imaging detectors (imagers) 106A and 106B may form an imaging system. In one embodiment, imaging sources 108A and 108B are X-ray sources. In one embodiment, for example, two imaging sources 108A and 108B may be nominally aligned to project x-ray beams through a patient from two differing angular positions (e.g., separated by 90 degrees, 45 degrees, etc.) and aimed through the patient on treatment couch 110 toward respective detectors 106A and 106B. In another embodiment, a single large imager can be used that would be illuminated by each x-ray imaging source. Alternatively, other numbers and configurations of imaging sources and detectors may be used. The imaging detectors 106 are illustrated as being flat (i.e., parallel to the floor), but the imaging detectors 106 may, alternatively, be angled.
A digital processing system may implement algorithms to register images obtained from the imaging system with pre-operative treatment planning in order to align the patient on the treatment couch 110 with the radiation delivery system 100, and to precisely position the radiation treatment source 102 with respect to the target volume. Registration and alignment techniques are known in the art; accordingly, a detailed description is not provided.
In the illustrated embodiment, treatment couch 110 is coupled to a couch position system 112 (e.g., robotic couch arm) having multiple (e.g., 5 or more) degrees of freedom. Couch position system 112 may have five rotational degrees freedom and one substantially vertical, linear degree of freedom. Alternatively, couch positioning system 112 may have six rotational degrees of freedom and one substantially vertical, linear degree of freedom or at least four rotational degrees of freedom. Couch positioning system 112 may be vertically mounted to a column or wall, or horizontally mounted to a pedestal, floor or ceiling. Alternatively, the treatment couch 112 may be a component of another mechanical mechanism, such as the Axum™ treatment couch developed by Accuray, Inc. of California, or be another type of conventional treatment table known to those of ordinary skill in the art.
Prior to delivery of the treatment plan to a patient, it is important to execute quality assurance (“QA”) mechanisms to ensure radiation treatment delivery system 100 is properly aligned and configured. These QA mechanisms, also referred to as confidence checks, validate the image guidance system, the couch positioning system, the source positioning system, and radiation treatment source 102, itself, which are all calibrated and aligned with each other. If anyone of these subsystems is misaligned with one or more other subsystems, a treatment plan could be erroneously delivered to a patient's detriment.
QA processing system 114 is communicatively coupled to target detector 116 (e.g., wired or wireless link) to receive QA data therefrom. QA processing system 114 may receive exposure images generated in response to a dose of radiation being delivered to target detector 116 from radiation treatment source 102. QA processing system 114 may then analyze the exposure images to determine whether radiation treatment delivery system 100 is aligned and calibrated. In one embodiment, target detector 116 may be implemented using the IMRTlog sensor from Cardinal Health, Inc. of Dublin, Ohio or the Mapcheck two dimensional detector by Sun Nuclear, Corp. of Melbourne, Fla. These detectors provide real-time feedback to QA processing system 114. Other radiation detecting equipment may be used as well. In one embodiment, QA processing system 114 may further be coupled to imaging detectors 108 to receive additional QA data therefrom.
QA processing system 114 may be a stand alone machine dedicated for QA analysis or integrated into other control systems of radiation treatment delivery system 100. Furthermore, although QA processing system 114 is illustrated as a single entity, it should be appreciated that
Target detector 116 is stationed at a known, fixed reference point using the iso-post 118. In one embodiment, iso-post 118 is a rigid support that positions target detector 116 at an imaging iso-center of the image guidance system. Typically, the imaging iso-center is the location at which the x-ray beams from the x-ray sources intersect (i.e., a machine iso-center), where the patient is typically located during treatment. In one embodiment, the imaging geometry of the imaging system may provide two or more imaging centers. Multiple imaging centers may establish multiple treatment frames of reference and enable image-guided radiation treatment from above a patient and from below a patient.
It should be appreciated that any rigid support may be used to station target detector 116 at the known, fixed reference point. In one embodiment, target detector (and iso-post 118) may be incorporated into treatment couch 110 to validate the ability of the couch positioning system to accurately maneuver treatment couch 110. With target detector 116 positioned at the known, fixed reference point, it is possible to determine whether the image guidance system is aligned.
In one embodiment, the radiation treatment system may be another type of treatment delivery system, such as, for example, a gantry based (isocentric) intensity modulated radiotherapy (“IMRT”) system 200, as shown in
The iso-crystal 406 may be substantially spherical. In one embodiment, the iso-crystal 406 has a diameter on the order of 20-200 microns. In one embodiment, the iso-crystal 406 has a diameter of about 2 mm. Alternatively, iso-crystal 406 may have a diameter less than 2 mm or greater than 2 mm.
The light gathering element may be fabricated from materials such as polymethylmethacrylate (PMMA), polytetrafluoroethylene (also referred to as TEFLON® or PTFE), polymer, and the like. In an alternative embodiment, the iso-crystal 406 may be made from other materials such as ruby, or other similar materials selected to match the laser used for the radiation source 102. It should be noted that some materials such as PTFE have a light-scattering property.
In one embodiment, the iso-crystal has a light-scattering surface. The outer surface 409 of the iso-crystal 406 may be altered to have light-scattering surface properties. For example, the outer surface 409 of the iso-crystal 406 may be altered by roughening the outer surface. For example, PMMA's light scattering properties are not as effective as PTFE; however, by roughening the outer surface of a PMMA iso-crystal, the PMMA iso-crystal may become more light scattering. Other surface altering processes as known to those of skill in the art may be used to alter the outer surface 409 of the iso-crystal 406.
The light gathering element may include a dielectric coating 410, as shown in
In one embodiment, the light gathering element may include a wave length conversion material. The iso-crystal 405 and/or the dielectric coating 410 may include the wave length conversion material. In one embodiment, the wave length conversion material is a scintillating material. Exemplary scintillating materials include thallium-doped sodium iodide crystals, barium fluoride, cesium iodide, bismuth germinate, lanthanum bromide, lutetium iodide, phosphors, polystyrene, and the like. It will be appreciated that other wave length conversional materials may be used
In one embodiment, the optical fiber 408 and the iso-crystal 406 have a unitary construction. The iso-crystal 406 and the optical fiber 408 may be formed from the same material. For example, the iso-crystal and optical fiber may both be made of PMMA. As discussed above, because PMMA does not scatter light as well as some other materials, the PMMA iso-crystal should be coated or the outer surface should be altered so that it has light-scattering surface properties.
The optical fiber has a gathering angle β, which is the angle at which the base of the optical fiber can detect light. The captured light within the gathering angle α is transmitted through the optical fiber to the target detector 116 (not shown), as described hereinafter. In one embodiment, the gathering angle β of the optical fiber 408 is any angle or range of angles between approximately 220° and 240°. Alternatively, the gathering angle β of the optical fiber 408 may be less than 220° or greater than 240°. For example, in one embodiment, the gathering angle β of the optical fiber 408 may be approximately 180°.
The method continues by forming the light gathering element, such as iso-crystal 406, at substantially the base of the optical fiber (block 504). It will be appreciated by those of skill in the art that the light gathering element can be formed prior to, subsequent, or concurrent with formation of the optical fiber.
The light gathering element has an outer surface, which has a first portion and a second portion. The first portion of the outer surface of the light gathering element is positioned at substantially the base of the fiber, and the second portion of the light gathering element is substantially omni-directional. The light gathering element and optical fiber together form a light gathering assembly. In one embodiment, the ends of the optical fiber are cleaned and/or otherwise prepared for light transmission, as known to those of skill in the art.
In one embodiment, the light gathering element is also extruded or molded. In another embodiment, the light gathering element is machined and/or molded separate from the optical fiber and attached to the fiber with, for example, an epoxy. Other materials or processes may be used to attach the optical fiber and the light gathering element. In one embodiment, the light gathering element and optical fiber are a unitary construction.
At block 506, the light gathering assembly is inserted into a cartridge having a detector. As explained above, the light gathering assembly may optionally be placed into a holder, such as holder 400, which is subsequently removably placed into the cartridge, such as cartridge 310. In one embodiment, the cartridge and/or holder are made from a plastic, such as, for example, DELRIN®. It will be appreciated that other plastic or non-plastic materials may be used to make the cartridge and/or holder.
At block 508, the cartridge is removably inserted into the iso-post. As explained above with reference to
Thus, the holder and/or cartridge can be replaced without replacing the entire iso-post 118, which minimizes the requirement of expert field service personnel to replace the light gathering element. In addition, because the iso-crystal is substantially spherical and made from different materials than the prior art iso-crystals, the radiation treatment delivery system does not necessarily need to be re-calibrated when the iso-crystal is replaced.
It should be noted that the methods and apparatus described herein are not limited to use only with medical diagnostic imaging and treatment. In alternative embodiments, the methods and apparatus herein may be used in applications outside of the medical technology field, such as industrial imaging and non-destructive testing of materials (e.g., motor blocks in the automotive industry, airframes in the aviation industry, welds in the construction industry and drill cores in the petroleum industry) and seismic surveying. In such applications, for example, “treatment” may refer generally to the application of radiation beam(s).
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.