Ionization detector for radiation therapy, quality assurance systems, and methods using the same

Abstract

The present disclosure describes a detector system for characterizing a therapeutic beam. The detector system may include numerous additional or alternative features and, as an example, may include a detection unit comprising an intensity sensor layer configured to generate a signal in response to ionization events, an x-position sensor layer having a plurality of x-position detector strips and configured to generate a signal in response to one or more ionization events, and a y-position sensor layer comprising a plurality of y-position detector strips and configured to generate a signal in response to one or more ionization events. Signal data may be timestamped and associated with timestamped beam trigger demand data. Processing may allow three-dimensional spatial characterization and fluence characterization of the therapeutic beam. Also disclosed are methods of characterizing a therapeutic beam.

Description

IONIZATION DETECTOR FOR RADIATION THERAPY, QUALITYASSURANCE SYSTEMS, AND METHODS USING THE SAMECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No.63 / 643,257, filed on May 6, 2024 and is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to radiation therapies for treating cancer. Aspects of the present disclosure relate to ionization chambers for conducting quality assurance checks on radiation equipment. Certain specific aspects of the present disclosure relate to ionization chambers for conducting quality assurance checks on equipment generating radiation or particle beams, such as proton beams. Other certain specific aspects of the present disclosure relate to methods of making and methods of using ionization chambers for conducting quality assurance checks on equipment generating radiation or particle beams, such as proton beams or other hadronic or heavy ion beams.BACKGROUND

[0003] Cancer treatments broadly include surgery, chemotherapy, and radiation therapy. Radiation therapy involves subjecting the part of the body containing cancer to focused beams of radiation. The radiation may be electromagnetic radiation, such as X-rays, or particle radiation, such as protons or heavier charged nuclei. The radiation therapy imparts high amounts of energy to cancerous tissue, causing the destruction of cancerous cells. Ideally, radiation therapy minimizes damage to the surrounding healthy tissue.

[0004] In certain circumstances, radiation therapy such as proton radiation has advantages over X-ray radiation in the treatment of cancer. When an X-ray beam encounters human tissue, it releases a relatively high amount of energy at the point of entrance and continues to release energy as the X-rays travel through and exit thebody. All tissue within the path of the X-ray beam receives an energy dosage, with the tissue at the point of entrance receiving the highest relative dosages. Doctors providing X-ray therapy to a deep tumor, for example, need to provide X-rays at a high enough energy to kill the deep cancerous tissue. Those X-rays will necessarily pass higher amounts of energy to the healthy tissue superficial to the cancerous tissue. Such high levels of energy imparted to healthy tissue risks destroying the healthy tissue in order to also destroy the deeper cancerous tissue. Because of this, X-ray radiation therapy can be particularly problematic if the cancerous tissue is situated such that the X-ray beam must pass through critical organs or the spinal cord.

[0005] The energy delivery mechanism of proton therapy differs from that of X- ray therapy. When ionized particles such as protons travel through matter, the deposition of energy from the proton into the matter increases as the velocity of the proton slows. As the proton comes to a complete stop, it transfers a large burst of energy to the surrounding matter. This sudden burst of energy is known as a Bragg peak.

[0006] Additionally, protons of a certain energy will travel to a specific depth through a given matter. The depth of penetration can thus be controlled by controlling the energy of the proton beams. The energy of the protons in a proton beam can be precisely controlled. As most of the protons’ energy will be released only as the protons approach their final depth, the radiation dose can be much more precisely limited to tissues in a particular depth, sparing tissue both superficial and deep to the targeted tissue.

[0007] In the context of irradiating a tumor with protons, most of the ionizing energy can be localized to a precise depth in the tumor; relatively little ionizing energy is imparted to the tissue before the tumor that the proton beam passes through, and almost no ionizing energy is imparted to the tissue beyond the tumor.

[0008] Proton beams can also be delivered in a precise shape. Thus, the overall shape and depth of a cancerous tumor can be precisely targeted with proton therapy. A newer approach to proton delivery, known as discrete spot scanning or pencil-beam scanning, was implemented in the United States around 2008. The adoption of discretespot scanning or pencil-beam scanning has led to a surge in the adoption of proton therapy in the United States.

[0009] Prior proton-beam-scanning approaches delivered a relatively broad beam of scattered protons to a volume that roughly corresponded to the distal contours of a tumor. Discrete spot scanning, in contrast, deposits a beam of protons in an extremely fine beam and may focus thousands of beams at a given tumor depth, each at a precise location, and across many depths of the tumor. As a result, discrete spot scanning results in a proton-therapy treatment with the tumor being irradiated very precisely, conforming radiation delivery to the tumor and minimizing the impact to surrounding healthy tissue.

[0010] Radiation therapy treatment is complex, and discrete spot scanning proton therapy adds significant complexity to the treatment process. Each patient receives a unique treatment plan to deliver radiation very specifically to that patient’s tumor. Each unique treatment plan must undergo a rigorous quality assurance test to ensure that the proton beam is delivered to the patient as precisely as intended.

[0011] Additionally, while proton therapy can have advantages over X-ray therapy, the number of centers capable of administering proton therapy is dwarfed by the number of centers capable of administering X-ray therapy. The available qualityassurance equipment and software is primarily designed for X-ray therapy, with minor — but sub-optimal — adjustments to make such equipment and software passably suitable for proton therapy. Adapting such equipment and software to proton therapy quality assurance applications results in quality-assurance processes that are inefficient and less effective than would be feasible with tailored quality -assurance equipment and software.

[0012] One approach to proton therapy quality assurance programs utilizes a two- dimensional ionization chamber array disposed in a water phantom to sample the radiation fluence (energy per unit area) distribution. Since protons of a given energy travel only a certain distance through a medium such as water (or, analogously, human tissue), the radiation fluence distribution changes as a function of depth. Thus, it became common practice to shift the two-dimensional ionization chamber array to various clinically relevant depths and repeat measurements to obtain a more completepicture of the radiation fluence distribution across a volume. The two-dimensional ionization chamber array may be placed in a water tank phantom with remotely operated servo motors to position the array at selected depths. One significant drawback with this method, however, is the significantly increased acquisition time due to repeated radiation fluence acquisitions at various depths.

[0013] Several drawbacks to existing quality assurance systems and processes exist, leading to longer radiation fluence acquisition times, sub -optimal data quality, or both. As one example, existing systems and processes feature slow processing time relative to the radiation beam delivery rate. One drawback of the slow processing time is that only aggregate or integrated measurements may be taken; spot-by-spot capture would take a prohibitively long time, accounting for processing time, and would result in significant dead time during acquisition.

[0014] Another drawback to existing quality assurance systems and processes is the intrinsic resolution of existing systems. Typical resolution or spacing is approximately 0.762 cm, which is larger than the full width, half maximum (a measure of the width of the proton beam) of approximately half of the deliverable energies of proton beams from modem medical proton accelerators. A sharper resolution could increase the fidelity and quality of data obtained from quality assurance systems and processes.

[0015] Another drawback to existing quality assurance systems and processes is that the area of detection is typically 27 cm x 27 cm. Modem proton accelerators may deliver protons to an area about 40 cm x 30 cm. Thus, to obtain a full radiation fluence sample across entire field of use, the two-dimensional ionization chamber array must be laterally shifted between measurements at one depth to acquire a composite radiation fluence sample of 40 cm x 30 cm. As multiple depths are required, the undesirable increases in measurement time compound.

[0016] Another drawback to existing quality assurance systems and processes is that, on typical two-dimensional ionization chamber arrays, alignment markings result in positioning uncertainty. The amount of uncertainty can be as much as 2mm. Discrepancies of such magnitude can lead to imprecise monitoring of the proton beamspatial accuracy, which in turn can lead to an imprecise treatment, which may lead to a lower dose at the tumor target and potentially a higher dose to healthy tissue.

[0017] Another drawback to existing quality assurance systems and processes is that typical two-dimensional ionization chamber arrays must be disposed in a water tank (or phantom) to mimic the protons’ travel through human tissue. The water in the tank must be filled at the beginning of a quality assurance measurement and emptied at the conclusion of a quality assurance measurement. This undesirably takes time and increases logistical requirements, as the water tank must be located near both a water source and a drain.

[0018] Indeed, it is a priority for many proton therapy centers to operate as continuously as possible, as the limited number of centers creates high demand. Time spent in quality assurance is time not available for patient treatment. Increased time demands in quality assurance processes due to quality assurance equipment that fails to particularly account for clinical realities in proton therapy is a significant issue in the field. Moreover, the high construction cost of a proton therapy centers means that, even with continued increasing demands for proton therapy treatment, proton therapy centers are unlikely to become widespread in the near future. Already, many proton therapy centers treat patients across multiple work shifts to meet demand for proton therapy. Since quality assurance processes must be undertaken separately from patient treatment, the efficiency of the quality assurance measurements is critically important. And optimizing the efficacy of quality assurance measurements is important to maintain patient safety and optimize tumor targeting.

[0019] Improved ionization detectors are needed to improve on the foregoing challenges in the art. Improved quality assurance processes for proton therapy are further needed to improve on the foregoing challenges in the art.SUMMARY

[0020] Aspects of the present disclosure may describe a radiation detector designed to specifically and efficiently monitor the beamlet-specific and / or integral spatial accuracy and output across the full field size of state of the art hadronic or ionic medical accelerators. This may be achieved by 1) improved localization features foraccurate detector positioning; 2) electronics with acquisition linked to an external port that may receive on and off triggers from hadronic or ionic accelerator, with processing speed sufficient to resolve discretized beamlets and / or individual beamlet centroids of a continuously delivered beam; 3) analysis software routines to assess beam momentum via determination of magnetic rigidity; and / or 4) analysis software routines that permit correlating the radiation treatment plan file (e.g., in DICOM or other format) to measured beam positions, for delivery quality assurance, selectively activating sub regions of detector for acquisition to improve processing speed and signal to noise ratios, or both.

[0021] One aspect of the present disclosure may describe a detector system including a detection unit. The detection unit may include an intensity sensor layer coupled to a periphery of the detection unit and configured to generate a signal in response to one or more ionization events; an x-position sensor layer coupled to the periphery of the detection unit, the x-position sensor layer comprising a plurality of x- position detector strips, each of the plurality of x-position detector strips disposed parallel to one another and configured to generate a signal in response to one or more ionization events; and a y-position sensor layer coupled to the periphery of the detection unit, the y-position sensor layer comprising a plurality of y-position detector strips, each of the plurality of y-position detector strips disposed parallel to one another and configured to generate a signal in response to one or more ionization events. The detector system may also include an electronics unit comprising a signal processor and a port configured to receive beam trigger demand data. The detector system may also include a vent. In the detector system, the x-position detector strips may be disposed perpendicular to the y-position detector strips; each of the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer may be separated by an air gap; each air gap may vent to ambient air via the vent; the intensity sensor layer may be electrically coupled to the signal processor; the x-position detector strips may be electrically coupled to the signal processor; and the y-position detector strips may be electrically coupled to the signal processor.

[0022] Detector systems according to examples of the present disclosure may be one integrated device or may be components located in different physical devices, such as a detector unit and a computer. Detector systems according to examples of thepresent disclosure may process timestamped signal data and timestamped beam trigger demand data to characterize an incident beam. Detector systems according to examples of the present disclosure may receive beam trigger demand data wirelessly or through a hardwired connection.

[0023] Detector systems according to examples of the present disclosure may have sensor layers arranged transversely relative to an expected axial direction of a beam. Sensor layers may be approximately planar and may be separated from each other by an air gap. Detector systems according to examples of the present disclosure may have sensor layers arranged in different orders. In one example, an intensity layer may be disposed closest to the beam source, followed by an x-position layer and then a y- position layer. In another example, an intensity layer may be disposed closest to the beam source, followed by a y-position layer and then an x-position layer. In another example, an intensity layer may be disposed between a y-position layer and an x- position layer (with either the y-position layer or the x-position layer being disposed closest to the beam source). In another example, an intensity layer may be disposed farthest from a beam source (with either the y-position layer or the x-position layer being disposed closest to the beam source).

[0024] Detector systems according to examples of the present disclosure may include a computational processor configured to process timestamped signal data and timestamped beam trigger demand data to characterize an incident beam.

[0025] Detector systems according to examples of the present disclosure may be configured to transmit signals generated in response to ionization events to the signal processor; the x-position detector strips may be configured to transmit signals generated in response to ionization events to the signal processor, and the y-position detector strips may be configured to transmit signals generated in response to ionization events to the signal processor. In certain examples, the signal processor may be a multichannel analog pulse processor. In other examples, each of the x-position detector strips may be electrically coupled to a dedicated x-position channel of the multichannel analog pulse processor and each of the y-position detector strips may be electrically coupled to a dedicated y-position channel of the multichannel analog pulse processor.

[0026] Detector systems according to examples of the present disclosure may comprise x-position detector strips and y-position detector strips having a pitch of 2.5mm. In other examples, the x-position detector strips and y-position detector strips may be constructed from a polyimide film covered by a conductor, such as copper- coated Kapton.

[0027] Detector systems according to examples of the present disclosure may include a desiccant and a filter in the vent, and the vent may fluidically couple the air gaps with the ambient air. Detector systems according to examples of the present disclosure may also include a Mylar shield layer. Detector systems according to examples of the present disclosure may further include one or more fiducials.

[0028] Also disclosed are methods for characterizing a hadronic or ionic beam. Methods for characterizing a hadronic or ionic beam according to certain examples of the present disclosure may include placing a detector on a patient support system; positioning the detector on the patient support system so that a detection portion of the detector is disposed transverse to a direction of expected travel of a beam; imaging the detector with an x-ray to locate one or more fiducials within the detector; adjusting the position of the detector or adjusting the position of the patient support system to place the one or more fiducials in an expected position; activating the beam, wherein, on activation, the beam is incident on the detection portion of the detector; recording the signals resulting from ionization events to obtain recorded signal data, the signals being generated on a plurality of detector strips in an x-position layer of the detection portion and on a plurality of detector strips in a y-position layer of the detection portion, the recorded signal data associating a magnitude of each signal with a specific detector strip; timestamping the recorded signal data to obtain timestamped signal data; receiving beam trigger demand data comprising timestamped data corresponding to one or more of several beam parameters including: the x and y positions, the current settings of final bending magnet, and the nominal energy of the beam at each timestamp; associating the timestamped signal data with the beam trigger demand data; and determining, based on the associated timestamped signal data and beam trigger demand data, a three-dimensional position of the beam at each time. The detector-measured x and y positions linked via timestamp to the final bending magnet current may be used to compute the magnetic rigidity of the beam and thereby deduceand confirm the beam energy and / or momentum. In some examples, methods may further include recording the signals generated from an intensity layer of the detection portion and displaying a report comprising a three-dimensional spatial and fluence characterization of the beam. Other specific examples may include adjusting a patient treatment plan based at least in part on the displayed report.

[0029] The beams characterized in certain specific examples may include proton beams, neutron beams, carbon beams, hadronic beams, or heavy ion beams.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing and other features of the present disclosure will become more fully apparent from the following description, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several aspects in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings. One of skill in the art may appreciate that certain features may be optional and that features or aspects of one example may be utilized or combined with other features highlighted in another example. Further, each and every aspect shown and described may not be necessary; rather, various aspects are shown or described as potential example features that may be included. In the drawings:

[0031] Fig. l is a graphical depiction comparing the relative energy deposition of X-ray radiation therapy and proton-beam radiation therapy as a function of tissue depth.

[0032] Fig. 2 is a top view of a detector system in accordance with one or more aspects of the present disclosure.

[0033] Fig. 3 is a sectional view of a detector module in accordance with one aspect of the present disclosure.

[0034] Fig. 4 is a sectional view of a detector module in accordance with another aspect of the present disclosure.

[0035] Fig. 5 is a sectional view of a detector module in accordance with another aspect of the present disclosure.

[0036] Fig. 6 is a top view of a simplified example of strips of an x-profile sensor layer in accordance with an aspect of the present disclosure.

[0037] Fig. 7 is a top view of a simplified example of strips of a y-profile sensor layer in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION

[0038] In this detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative examples described in the detailed description, drawings, and potential points of novelty are not limiting. Other aspects may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as described herein, and illustrated in the Figures, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. An alternative description is not necessarily a statement of identity or equivalence.

[0039] Aspects of the present disclosure are directed to systems, apparatus, and processes for conducting quality assurance measurements of radiation beams used in radiation therapies. Systems, apparatus, and processes disclosed herein may be particularly useful for conducting quality assurance measurements of proton beams used in proton therapy for treating cancer. Systems, apparatus, and processes disclosed herein may also have applicability for conducting quality assurance measurements of heavy ion beams (such as carbon) used in particle therapy for treating cancer, and / or x- ray beams used in electromagnetic therapy for treating cancer.

[0040] Certain specific aspects of the present disclosure are directed to detectors for detecting the fluence and position of radiation beams, including detectors capableof detecting the position and / or intensity of proton beams. Detectors according to the present disclosure may have various configurations, as described in more detail herein.

[0041] Other specific aspects of the present disclosure are directed to quality assurance systems for conducting quality assurance measurements on hadronic and ionic beams used for radiation therapy, including proton beams for proton therapy, heavy ion beams for other particle therapies, and x-rays for x-ray therapy. Aspects of the present disclosure may be described in more detail using proton beams as an illustrative example. Quality assurance systems of the present disclosure may include detectors for detecting the intensity and / or position of radiation beams; electronics for collecting detection signals and processing such signals; and software for sorting, processing, analyzing, and displaying data ultimately resulting from detection signals.

[0042] Further aspects of the present disclosure are directed to methods for conducting quality assurance measurements on radiation beams used for radiation therapy, including proton beams for proton therapy, heavy ion beams for other particle therapies, and x-rays for x-ray therapy. Methods may include one or more of the following steps: positioning a detector for detecting the position and / or intensity of a radiation beam, imaging the detector with an x-ray to determine the position of the detector with respect to the intended target of a radiation beam, re-positioning the detector based on the location and / or orientation of one or more fiducials embedded within the detector, irradiating the detector with the radiation beam, collecting ionization signals resulting from ionization events resulting from the radiation beam in the detector, processing the ionization signals to generate ionization data, presenting the ionization data in a usable format, and analyzing the presented ionization data. Ionization data corresponding to specific ionization events may be timestamped and associated with corresponding time data from a radiation beam trigger to determine specific radiation beam energies at given times and associate such beam energies with the timestamped ionization data.

[0043] Fig. l is a graphical depiction comparing the relative energy deposition of x-ray radiation therapy and proton-beam radiation therapy as a function of tissue depth. The x-axis corresponds to tissue depth in cm. The y-axis corresponds to the relative dose from radiation therapy. Thus, the graph illustrates where and howradiation therapies deposit energy into the body during treatment. Region 101 represents tissue depth that is shallow to the tumor (i.e., extending from the skin’s surface to the tumor). Region 102 represents the tissue depth containing a tumor. Line 102a represents the shallow depth of a tumor, and line 102b represents the deep depth of a tumor. Region 103 represents tissue depth that is deep to the tumor. A first curve 110, represented by alternating dashes and dots, represents the depths of energy deposition of an x-ray beam traveling through the body. The x-rays deposit relatively more energy on first contact with human tissue at shallow depths. As the x-rays continue through the body, relatively less energy is deposited. The x-rays will pass through a targeted tumor, eventually passing through the body entirely, including tissue deep to the tumor. Treatment with an x-ray beam must account for energy loss through region 101 and must be energetic enough to pass the therapeutically effective radiation dose to region 102 containing the tumor. And, as shown in the graph, x-rays continue past the tumor, irradiating healthy tissue in region 103 that is deep to the tumor.

[0044] In contrast, curve 120, represented by dashes, is known as a spread-out Bragg peak and represents the total depths of energy deposition of proton beams comprising proton therapy. Unlike x-rays, protons will only travel a certain distance through the body before coming to a complete stop. A proton will deposit relatively little energy while moving fast and deposits more and more energy the more it slows down. At the moment it comes to a complete stop, it releases a burst of energy, represented graphically as a Bragg peak. Treatment with proton beams may include irradiation with protons having different energies, such that the protons will come to a stop at specified depths in the body. Curves 131, 132, 133, 134, and 135 represent the depths of five proton beams of different energies. Points 140 represent the Bragg peaks of each of proton beam represented by curves 131, 132, 133, 134, and 135. The total energy represented by the sum of the proton beams represented by curves 131, 132, 133, 134, and 135 equals the energy in the spread-out Bragg peak curve 120, which represents the energy deposition of a proton therapy overall. Compared to curve 110, in curve 120, relatively less energy is deposited in the healthy tissue in region 101, most of the energy is deposited in region 102 containing the tumor, and very little energy is deposited in the healthy tissue of region 103 deep to the tumor.

[0045] As may be evident from Fig. 1, since most of the energy from proton therapy is deposited into a tumor in region 102, the dose to healthy tissue can be reduced, and the dose to the tumor can be maximized.

[0046] To realize these benefits, centers offering proton therapy must take great care to ensure that the proton beams travel to the correct positions and depths within the patient. Each patient is assigned a unique treatment plan, which includes visualizing the tumor to determine its precise location and contours. A treatment plan is developed so that proton beams of varying energies will deposit protons (and their ionizing energies) to precise locations in the tumor. To ensure that the proton beams are directed to the correct tissue volume, centers offering proton therapy must conduct rigorous quality assurance measurements to ensure that actual performance matches expected performance.

[0047] Certain specific aspects of the present disclosure are directed to detectors for detecting the fluence and / or position of radiation beams, including detectors capable of detecting the position and / or intensity of proton beams. Detectors according to the present disclosure may have various configurations, as described in more detail herein.

[0048] Fig. 2 is a top view of a detector system in accordance with one or more aspects of the present disclosure. Detector system 200 may include a detector housing 210 and electronics housing 220. Detector module 230 may be disposed in detector housing 210. Electronics housing 220 may include vent holes 221 to vent heat generated by electronics within electronics housing 220. Detector housing 210 may include one or more fasteners 211 for securing portions of detector housing 210 to one another and / or to electronics housing 220. Electronics housing 220 may include one or more fasteners 222 for securing portions of electronics housing 220 to one another and / or to detector housing 210. Detector system 200 may be vented such that the air pressure within detector module 230 (or within ion chambers that comprise detector module 230) matches ambient air pressure. Detector system 200 may include one or more sensors configured to measure local air pressure. Measurements from the one or more sensors can be sent to a processor, where an air density correction factor may beapplied to detector readings via software processing following acquisition of detector readings.

[0049] Detector module 230 may include active detector area 231 and detector periphery 232. Detector periphery 232 may include one or more fasteners 233 for securing detector module 230 within detector housing 210. Detector periphery 232 may be constructed of a radiolucent material such as machined or molded plastic, or any other suitable material. Detector housing 210, detector periphery 232, or any suitable area on detector system 200 may include one or more alignment grooves. As one example, an alignment groove may comprise a straight line etched into an appropriate spot on the detector system 200 (such as a plastic or metal housing piece) that may be visible on examination of the exterior of detector system 200. Alignment grooves may align a detector system 200 to fixed lasers in treatment rooms. In an example, the one or more alignment grooves may be approximately 1 -2 cm in length and less than one mm in width.

[0050] Detector module 230 may be constructed of one or more sensor layers. In one aspect of the present disclosure, detector module 230 comprises an x-profile sensor layer 241 and a y-profile sensor layer 242. Optionally, detector module 230 may further comprise one or more intensity sensor layers 243.

[0051] Each of x-profile sensor layer 241, y-profile sensor layer 242, and, where included, intensity sensor layer 243 may comprise a plurality of detector strips. Each detector strip may be constructed of a conductor-coated polyimide film, such as copper-coated Kapton. The strips of copper-coated Kapton may be used to collect signals resulting from incidence of ionizing radiation. Mylar may be used to surround or encase detector module 230 to protect detector module 230 from contaminants such as dust, or from physical wear-and-tear damage from moving the detector system 20 over time. Alternatively, Mylar could be utilized as a top and bottom later for a similar protective purpose. Instead of copper-coated Kapton, detector strips could be constructed from a copper-coated polyimide film, aluminum-coated polyimide film, or graphite-coated polyimide film.

[0052] Fig. 3 is a sectional view of a detector module 230a in accordance with an aspect of the present disclosure. Detector module 230a may comprise a y-profilesensor layer 242, an x-profile sensor layer 241, and, optionally, an intensity sensor layer 243. X-profile sensor layer 241 may principally comprise ionization strip detectors, that may be vented to open air. In one aspect, x-profile sensor layer 241 may comprise a plurality of strips of conductive material. For example, x-profile sensor layer 241 may comprise a plurality of strips of copper-coated polyimide film, such as copper-coated Kapton. Each of the plurality of strips in x-profile sensor layer 241 may be disposed substantially parallel to and coplanar with one another. Each of the plurality of strips in x-profile sensor layer 241 may be electrically coupled to one channel of a multichannel analog pulse processor, or other suitable means for processing signals generated from one or more strips in the x-profile sensor layer 241, such as an analog-to-digital signal converter coupled to a digital processor. Alternatively, adjacent strips of copper-coated polyimide may be electrically coupled to each other, and the coupled signal may be coupled to the processor, signal converter, or other electronics for processing the detector signals.

[0053] Above the uppermost layer (from the perspective of the sectional view of Fig. 3 and, which, in the example of Fig. 3, is the intensity sensor layer 243) and between adjacent sensor layers are air gaps 247. Air molecules in air gaps 247 become ionized when ionizing radiation in beam 246 passes through the air gaps 247. Ionized air molecules become charged, enabling their detection on detector strips in intensity sensor layer 243, x-profile sensor layer 241, and y-profile sensor layer 242.

[0054] X-profile sensor layer 241 may include one or more fiducials 244. Fiducials 244 disposed in x-profile sensor layer 241 may be constructed from a radiopaque material such as gold or copper. Fiducials 244 may be small pieces of gold or copper, such as BB-sized pieces. Preferably, fiducials 244 are constructed from a high atomic number metal such as gold or copper to show up clearly in x-ray imaging localization and are small in size to improve localization uncertainty. Fiducials 244 disposed in x- profile sensor layer 241 may be used to align and / or position detector system 200 at the beginning of a quality assurance measurement process. For example, detector system 200 may be placed on a gantry or other positioning support and positioned to receive a radiation beam. Detector system 200 may be imaged using x-rays to reveal the position and / or alignment of fiducials 244 with respect to a predetermined position or alignment. If necessary, the position, alignment, or both of detector system 200 orthe patient support system may be adjusted to place detector system 200 in the correct position and alignment based on the location of fiducials 244.

[0055] In examples according to Fig. 3, x-profile sensor layer 241 may be disposed above y-profile sensor layer 242. Also in examples according to Fig. 3, x-profile sensor layer 241 may be disposed below intensity sensor layer 243, where examples include optional intensity sensor layer 243.

[0056] Detector module 230a may include a y-profile sensor layer 242. In one aspect of examples according to Fig. 3, y-profile sensor layer 242 may comprise a plurality of strips of conductive material. For example, y-profile sensor layer 242 may comprise a plurality of strips of copper-coated polyimide film, such as copper-coated Kapton. Each of the plurality of strips in y-profile sensor layer 242 may be disposed substantially parallel to and coplanar with one another. Each of the plurality of strips in y-profile sensor layer 242 may be electrically coupled to one channel of a multichannel analog pulse processor, or other suitable means for processing signals generated from one or more strips in the y-profile sensor layer 242, such as an analog-to-digital signal converter coupled to a digital processor. Alternatively, adjacent strips of copper-coated polyimide may be electrically coupled to each other, and the coupled signal may be coupled to the processor, signal converter, or other electronics for processing the detector signals.

[0057] Y-profile sensor layer 242 may include one or more fiducials 245. Fiducials 245 disposed in y-profile sensor layer 242 may be constructed from a radiopaque material such as gold or copper. Fiducials 245 disposed in y-profile sensor layer 242 may be used to align and / or position detector system 200 at the beginning of a quality assurance measurement process. Fiducials 245 may be constructed similarly to fiducials 244, except disposed within y-profile sensor layer 242. For example, detector system 200 may be placed on a gantry or other positioning support and positioned to receive a radiation beam. Detector system 200 may be imaged using x-rays to reveal the position and / or alignment of fiducials 245 with respect to a predetermined position or alignment. If necessary, the position, alignment, or both of detector system 200 may be adjusted to place detector system 200 in the correct position and alignment based on the location of fiducials 245.

[0058] In examples according to Fig. 3, y-profile sensor layer 242 may be disposed below x-profile sensor layer 241. Also in examples according to Fig. 3, y-profile sensor layer 242 may be disposed below intensity sensor layer 243, where examples include optional intensity sensor layer 243.

[0059] While the plurality of strips in each of x-profile sensor layer 241 and y- profile sensor layer 242 may be disposed parallel to one another within each layer, the strips comprising x-profile sensor layer 241 may be disposed substantially perpendicular to the strips comprising y-profile sensor layer 242.

[0060] In use, ions in ionic beam 246 (e.g., protons in proton beam 246) targeted toward detector module 230a may cause ionization events in the atmosphere within detector module 230a. Such ionization events may cause an electrical current to be generated. Detector module 230a may be vented to open air. Air molecules may become ionized when beam 246 becomes incident on the molecules, and the charged, ionized air molecules may be pulled toward the cathode or anode, yielding a measurement signal. The measurement may be scaled computationally to correct for temperature and pressure using the equation PV=nRT. The resulting electrical current may be detected as a signal on one or more strips of x-profile sensor layer 241 and y- profile sensor layer 242. The magnitude of the signal may be larger on strips closer to the ionization event. Thus, for a given ionization event, by detecting the largest current on a strip of the x-profile sensor layer 241, an x-coordinate of the ionization event, and thus the x-coordinate of the proton (or other ion) causing the ionization event, can be determined. Similarly, by detecting the largest current on a strip of the y-profile sensor layer 242, a y-coordinate of the ionization event, and thus the y-coordinate of the proton causing the ionization event, can be determined. Combining the coordinates, a two-dimensional position of an ionic beam 246 (e.g., a proton beam 246) can be determined.

[0061] In an example, each of the strips comprising x-profile sensor layer 241 and each of the strips comprising y-profile sensor layer 242 may comprise a plurality of small-volume chambers of air. An opposing voltage bias may be applied to two portions of the air chamber (e.g., a top portion and a bottom portion) and, as ions are created by the radiation in the beam passing through the strips, the ions are drawntoward the oppositely charged portions. Signals may thus be generated and sent to electronics configured to record and measure and / or process the signals.

[0062] Strips in each of x-profile sensor layer 241 and y-profile sensor layer 242 may have a pitch, or spacing between the ionization detector embedded within and along the strips. In an example, x-profile sensor layer 241 and y-profile sensor layer 242 may have a pitch of about 2.5 mm. Detectors having other pitches may be used. A smaller pitch may increase resolution and cost, but may decrease sensitivity. A larger pitch may decrease resolution and cost, but may increase sensitivity. A pitch of about 2.5mm has been found to be a preferred value for detectors for ionic beams 246, such as proton beams 246, but other pitch values can be utilized in other examples.Software processing may be used to determine the maximum radiation detection of a typically gaussian distributed hadron or ion beamlet at a position uncertainty about one order of magnitude less than intrinsic spacing of strip ionization detectors.

[0063] In an example, x-profile sensor layer 241 may include about 128 strips with a pitch of about 2.5 mm. In an example, y-profile sensor layer 242 may include about 160 strips with a pitch of about 2.5mm. Such an arrangement may provide an active detection area of detector module 230 of about 320 mm x 400 mm. Other arrangements may be constructed, depending on the desired size of the detector, ability to process discrete signals, and the like. A construction as described may provide a spatial resolution of less than about 0.3 mm.

[0064] As may be recognized by a person of ordinary skill in the art, a detector may be constructed with strips having different pitches or numbers of detector strips, resulting in detectors of different sizes. A person of ordinary skill in the art may know the approximate area of a full deliverable field of a beam accelerator and can construct a detector large enough to encompass the full deliverable field of the beam accelerator. The present disclosure encompasses such arrangements.

[0065] Optionally or additionally, detector module 230a may include an intensity sensor layer 243. Intensity sensor layer 243 may be constructed of a conductor-coated polyimide film, such as copper-coated Kapton. Instead of copper-coated Kapton, intensity sensor layer 243 could be constructed from a copper-coated polyimide film, aluminum-coated polyimide film, or graphite-coated polyimide film. In anembodiment, the conductor-coated polyimide film may be disposed across substantially the entire area of detector module 230a. Intensity sensor layer 243 may detect ionization events resulting from ionic beam 246 (e.g., proton beam 246), generating a signal resulting from the ionization events. Intensity sensor layer 243 may be electrically coupled to one channel of a multichannel analog pulse processor. The magnitude of the signal from intensity sensor layer 243 may increase as the number of protons in proton beam 426, and thus its intensity, increases.

[0066] Fig. 4 is a sectional view of a detector module 230b in accordance with another aspect of the present disclosure. Detector module 230b according to the example of Fig. 4 is largely the same as detector module 230a depicted in and described with respect to Fig. 3, except with respect to the location of fiducials 244 and fiducials 245. In examples according to detector module 230b, Fiducials 244 and fiducials 245 may be disposed in intensity sensor layer 243. The construction and purpose of fiducials 244 and fiducials 245 in detector module 230b is the same as fiducials 244 and fiducials 245 in detector module 230a.

[0067] Fig. 5 is a sectional view of a detector module 230c in accordance with yet another aspect of the present disclosure. Detector module 230c according to the example of Fig. 5 is largely the same as detector module 230a depicted in and described with respect to Fig. 3 and detector module 230b depicted in and described with respect to Fig. 4, except with respect to the location of fiducials 244 and fiducials 245. In examples according to detector module 230c, Fiducials 244 and fiducials 245 may be disposed in x-profile sensor layer 241. The construction and purpose of fiducials 244 and fiducials 245 in detector module 230b is the same as fiducials 244 and fiducials 245 in detector module 230a and detector module 230b.

[0068] Fig. 6 is a top view of a simplified example of strips of x-profile sensor layer 241. In one aspect, x-profile sensor layer 241 may comprise a plurality of strips 251 of conductive material. For example, x-profile sensor layer 241 may comprise a plurality of strips 251 of copper-coated Kapton. Each of the plurality of strips 251 in x- profile sensor layer 241 may be disposed substantially parallel to and coplanar with one another. Each of the plurality of strips in x-profile sensor layer 241 may be electrically coupled to one channel of a multichannel analog pulse processor, or othersuitable means for processing signals generated from one or more strips 251 in the x- profile sensor layer 241. There may be a pitch p between strips 251. It should be understood that the depiction of x-profile sensor layer 241 is highly simplified. In an example, there may be about 128 strips 251 coplanar and disposed parallel to each other, each separated by the same pitch p. In an example, pitch p is equal to about 2.5 mm.

[0069] Fig. 7 is a top view of a simplified example of strips of y-profile sensor layer 242. In one aspect, x-profile sensor layer 241 may comprise a plurality of strips 252 of conductive material. For example, y-profile sensor layer 242 may comprise a plurality of strips 252 of copper-coated Kapton. Each of the plurality of strips 252 in y- profile sensor layer 242 may be disposed substantially parallel to and coplanar with one another. Each of the plurality of strips in y-profile sensor layer 242 may be electrically coupled to one channel of a multichannel analog pulse processor, or other suitable means for processing signals generated from one or more strips 252 in the y- profile sensor layer 242. There may be a pitch p between strips 252. It should be understood that the depiction of y-profile sensor layer 242 is highly simplified. In an example, there may be about 140 strips 252 coplanar and disposed parallel to each other, each separated by the same pitch p. In an example, pitch p is equal to about 2.5 mm.

[0070] Examples of the present disclosure have recited detectors having an x- profile sensor layer 241 and a y-profile sensor layer 242, each layer comprising a plurality of detector strips 252 separated by a pitch p, wherein the strips of x-profile sensor layer 241 are disposed substantially parallel to each other and substantially perpendicular to strips of y-profile sensor layer 242, resulting in an (x,y) grid. Such arrangements may be advantageously simple to construct while retaining good accuracy for (x,y) beam measurement. However, other arrangements are contemplated and examples including alternative arrangements are expressly made a part of this disclosure. For example, a detector module 230 may be constructed of a first position layer, a second position layer, and a third position layer, each of the first position layer, second position layer, and third position layer comprising a plurality of detector strips 252 separated by a pitch p. Detector strips 252 within each of the first position layer, second position layer, and third position layer may be disposed substantially parallel toone another. The detector strips 252 in the first position layer may be disposed at an angle of approximately 60 degrees from the detector strips 252 in the second position layer and the third position layer. The detector strips 252 in the second position layer may be disposed at an angle of approximately 60 degrees from the detector strips 252 in the first position layer and the third position layer. And the detector strips 252 in the third position layer may be disposed at an angle of approximately 60 degrees from the detector strips 252 in the first position layer and the second position layer. Such an arrangement may improve signal to noise ratio, but may result in a more complex and expensive construction. A person of ordinary skill in the art may recognize further arrangements that are within the spirit and scope of this disclosure.

[0071] Detector module 230 may include electronics for receiving signals from x- profile sensor layer 241, y-profile sensor layer 242, and intensity sensor layer 243. Electronics may be substantially disposed within electronics housing 220. Intensity sensor 243, and each strip 252 in y-profile sensor layer 242, and each strip 251 in x- profile sensor layer 242 may be coupled to a dedicated channel. In an example, each channel may be electrically coupled to a corresponding channel in a multichannel analog pulse processor. The multichannel analog pulse processor may accept analog input signals from each channel, convert each analog signal to digital data, associate the digital data from each analog signal with a timestamp, and pass the data to memory for further processing and analysis. The data may retain an indication of the analog channel from which the data was generated. Each timestamp may resolve down to the millisecond or even lower. In some examples, each timestamp may resolve down to a few nanoseconds.

[0072] In an example, memory in which data output from the multichannel analog pulse processor is stored may be coupled to a computer processor. Computer processor may process instructions to conduct one or more pre-processing steps on the data. For example, data may be pre-processed to bin data. For example, data corresponding to signal strength from the x-profile sensor layer 241 and the y-profile sensor layer 242 may be binned, which may aid in analyzing such data to determine the (x,y) position of incident protons. Additionally, timestamp data may be binned to aid in associating, for example, data from intensity sensor 243, x-profile sensor layer 241, and y-profilesensor layer 242. In an example, timestamp binning may be on the order of 1 ms or even less, which may allow for spot-by-spot position and intensity characterization.

[0073] Electronics housing 220 may include a port for receiving data from a proton accelerator trigger device. Spot-specific beam data, also known as demand data, from a proton accelerator trigger device, may also include timestamp data. The port for receiving demand data may be coupled to the computer processor and memory. The computer processor may utilize the timestamp data from detected signals and timestamp data from the demand data to associate the demand data with the detection data. Demand data may include the energy of the proton beam (e.g., in MeV) at a given time. Demand data may also be binned. Binned or unbinned demand data may be stored in memory for later analysis.

[0074] Computer processor may access binned or unbinned detector data. Using timestamps, computer processor may associate detector data corresponding to intensity sensor 243, x-profile sensor layer 241, and y-profile sensor layer 242. From such associations, the (x,y) coordinates of a proton beam, and the intensity or fluence of the proton beam, may be determined.

[0075] Computer processor may further access binned or unbinned demand data. Using timestamps, computer processor may associate the demand data with the detector data. By combining the detector data, which may yield accurate characterizations of the (x,y) coordinates of the proton beam and the intensity of the proton beam, with the demand data, which may include or allow for characterizations of the energy of the proton beam at a given time, computer processor may yield data characterizing the energy, (x,y) coordinates, and intensity of the proton beam according to time. As protons of a given energy will travel only a certain distance through a medium (e.g., human tissue), the energy of the proton beam may allow for accurate characterization of the depth the proton beam would travel in human tissue at a given time. The depth and (x,y) positional data allow determination of a precise three-dimensional location where the proton beam terminates. The intensity data allows for a determination of the dose delivered to that location.

[0076] In an example, demand data may be utilized in the following manner to characterize the energy of the proton beam. Charged particles, including protons,follow the right-hand rule under the influence of a magnetic field. Demand data may include data corresponding to the strength of the magnetic field at a given time, the current settings of final bending magnet, and the nominal energy of the beam at each timestamp. Based on the strength of the magnetic field, the radius of curvature for the charged particle can be determined by setting the Lorentz force equal to mass times centripetal acceleration:which can be rearranged to:This equation can be further rearranged to express magnetic rigidity, or Bp (B-rho), expressed in Tesla * meters (p = r). Energy may be determined from velocity and momentum:Since the m / q ratio is constant for beams of a single ionic species, such as protons or carbon nuclei, Bp can be related to kinetic energy, as a function of velocity, multiplied by a constant:

[0077] Ultimately, Bp and energy combine to determine the position of the proton beamlet at isocenter. Since the protons travel along a beamline of fixed dimension, tracking the magnetic rigidity (and consequently energy and momentum) can be performed solely by verifying the magnetic field strength and proton beamlet position.

[0078] Proton beam positional data (e.g., expressed in (x,y) coordinates) can be obtained from detector data as described above. Demand data may include the magnetic field strength data at a given time. Associating the demand data and thedetector data thus allows the energy of the proton beam to be determined, which may allow the depth of the proton beam in human tissue to be determined. The detector- measured positional coordinates (e.g., x and y positions) linked via timestamp to the final bending magnet current may be used to compute the magnetic rigidity of the beam and thereby deduce and confirm the beam energy and / or momentum. Some or all of the foregoing data may be utilized to characterize the proton beam accurately and completely in real time.

[0079] Computer processor may store the associated demand data and detector data for further analysis and / or display. For example, a program may access the associated demand data and detector data and display characterizations of the proton beam on a user interface. Such a program may allow a user to model a treatment plan with high accuracy. Combining the proton beam characterization data with other data, such as tumor imaging data, may allow for intuitive visualizations of a treatment plan.

[0080] Importantly, a detector system 200 as described may allow complete, accurate characterizations of a proton beam without use of a water phantom and without having to reposition detector system 200 and / or detector module 230. Detector system 200 may thus be utilized to provide a complete quality assurance measurement in one scan of the proton beam, without the need for multiple scans following detector repositioning and without the need for the time and attendant logistics of filling and emptying water phantoms. Use of detector system 200 as described herein may drastically reduce the time required to conduct quality assurance measurements to a fraction of what is typical.

[0081] While various aspects have been disclosed herein, other aspects will be apparent to those skilled in the art. The various aspects disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the claims.

Claims

CLAIMSWhat is claimed is:

1. A detector system, comprising: a detection unit comprising: an x-position sensor layer coupled to a periphery of the detection unit, the x-position sensor layer comprising a plurality of x-position detector strips, each of the plurality of x-position detector strips disposed parallel to one another and configured to generate a signal in response to one or more ionization events; and a y-position sensor layer coupled to the periphery of the detection unit, the y-position sensor layer comprising a plurality of y-position detector strips, each of the plurality of y-position detector strips disposed parallel to one another and configured to generate a signal in response to one or more ionization events; an electronics unit comprising a signal processor and a port configured to receive beam trigger demand data; and a vent; wherein the x-position detector strips are disposed perpendicular to the y-position detector strips; wherein each of the x-position sensor layer and the y-position sensor layer comprise a plurality of air chambers; wherein each air chamber vents to ambient air via the vent; wherein the x-position detector strips are electrically coupled to the signal processor; and wherein the y-position detector strips are electrically coupled to the signal processor.

2. The detector system of claim 1, further comprising an intensity sensor layer coupled to a periphery of the detection unit and configured to generate a signal in response to one or more ionization events; wherein the intensity sensor layer comprises one or more air chambers vented to ambient air via the vent; and wherein the intensity sensor layer is electrically coupled to the signal processor.

3. The detector system of claim 1, wherein the electronics unit is a part of the same physical device as the detection unit.

4. The detector system of claim 1, wherein the electronics unit comprises one or more electronics components in the same physical device as the detection unit and one or more electronics components in a computing device physically separate from the detection unit.

5. The detector system of claim 1, wherein the electronics unit is coupled to the detection unit via a wired electrical connection, a wireless data connection, or both a wired electrical connection and a wireless data connection.

6. The detector system of claim 5, wherein the electronics unit and the detection unit are physically separated from one another.

7. The detector system of claim 4, wherein the computing device is configured to process timestamped signal data and timestamped beam trigger demand data to characterize an incident beam.

8. The detector system of claim 2, wherein the electronics unit further comprises a computational processor configured to process timestamped signal data and timestamped beam trigger demand data to characterize an incident beam.

9. The detector system of claim 1, wherein the port is a wireless transceiver.

10. The detector system of claim 1, wherein the port is configured to accept a physical wire associated with a beam trigger device.

11. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the intensity sensor layer is disposed closest to the beam source, the y-position sensor layer is disposed farthest from the beam source, and the x-position sensor layer is between the intensity sensor layer and the y- position sensor layer.

12. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the intensity sensor layer is disposed closest to the beam source, the x-position sensor layer is disposed farthest from the beam source, and the y-position sensor layer is between the intensity sensor layer and the x- position sensor layer.

13. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the x-position sensor layer is disposed closest to the beam source, the y-position sensor layer is disposed farthest from the beam source, and the intensity sensor layer is between the x-position sensor layer and the y- position sensor layer.

14. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the x-position sensor layer is disposed closest to the beam source, the intensity sensor layer is disposed farthest from the beam source, and the y-position sensor layer is between the x-position sensor layer and the intensity sensor layer.

15. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the y-position sensor layer is disposed closest to the beam source, the intensity sensor layer is disposed farthest from the beam source, and the x-position sensor layer is between the y-position sensor layer and the intensity sensor layer.

16. The detector system of claim 2, wherein the intensity sensor layer, the x-position sensor layer, and the y-position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the y-position sensor layer is disposed closest to the beam source, the x-position sensor layer is disposed farthest from the beamsource, and the intensity sensor layer is between the y-position sensor layer and the x- position sensor layer.

17. The detector system of claim 2, wherein the intensity sensor layer is configured to transmit signals generated in response to ionization events to the signal processor, wherein the x-position detector strips are configured to transmit signals generated in response to ionization events to the signal processor, and wherein the y-position detector strips are configured to transmit signals generated in response to ionization events to the signal processor.

18. The detector system of claim 17, wherein the signal processor is a multichannel analog pulse processor.

19. The detector system of claim 18, wherein the intensity sensor layer is electrically coupled to an intensity channel of the multichannel analog pulse processor.

20. The detector system of claim 18, wherein each of the x-position detector strips is electrically coupled to a dedicated x-position channel of the multichannel analog pulse processor.

21. The detector system of claim 18, wherein each of the y-position detector strips is electrically coupled to a dedicated y-position channel of the multichannel analog pulse processor.

22. The detector system of claim 18, wherein the multichannel analog pulse processor comprises an intensity channel, a plurality of x-position channels, and a plurality of y- position channels; and wherein the intensity sensor layer is electrically coupled to the intensity channel, at least one x-position sensor strip is electrically coupled to each x- position channel, and at least one y-position sensor strip is electrically coupled to each y- position channel.

23. The detector system of claim 1, wherein the x-position sensor layer has a pitch of about 2.5 mm and the y-position sensor layer has a pitch of about 2.5 mm.

24. The detector system of claim 1, wherein the x-position detector strips are constructed from copper-coated polyimide film and the y-position detector strips are constructed from copper-coated polyimide film.

25. The detector system of claim 1, further comprising a housing disposed about a periphery of the detection unit, wherein the vent extends through the housing to fluidically couple the air chambers in the detection unit to the ambient air.

26. The detector system of claim 1, wherein the vent further comprises a filter and a desiccant.

27. The detector system of claim 2, further comprising a Mylar shield layer, wherein the Mylar shield layer, the intensity sensor layer, the x-position sensor layer, and the y- position sensor layer are arranged transversely relative to a direction of expected beam travel, and wherein the Mylar shield layer is disposed closest to the beam source.

28. The detector system of claim 1, further comprising a plurality of fiducials in the x- position sensor layer, the y-position sensor layer, or both the x-position sensor layer and the y-position sensor layer.

29. The detector system of claim 23, further comprising 128 x-position detector strips and 160 y-position detector strips.

30. The detector system of claim 17, wherein the electronics unit is configured to convert input signals from the intensity sensor layer, the x-position detector strips, and the y-position detector strips to digital signal data; associate the digital data for the input signals with timestamps; and associate the timestamped digital data for the input signals with timestamped beam trigger demand data.

31. The detector system of claim 30, wherein the digital data for the input signals comprises an association of each input signal with the intensity sensor layer, the specificx-position detector strip, or the specific y-position detector strip from which the input signal originated.

32. The detector system of claim 31, wherein the electronics unit is configured to bin the digital data for the input signals.

33. The detector system of claim 32, wherein the binning includes maintaining the data associated with the strongest signal for the x-position detector strips at a particular timestamp and the data associated with the strongest signal for the y-position detector strips at a particular timestamp and discarding the rest of the data associated with x- position detector strips and y-position detector strips at the particular timestamp.

34. The detector system of claim 30, wherein the timestamped beam trigger demand data further comprises an indication of the beam energy in MeV at each timestamp.

35. The detector system of claim 33, wherein the timestamped beam trigger demand data further comprises an indication of the beam energy in MeV at each timestamp.

36. The detector system of claim 35, wherein the electronics unit is configured to further process the timestamped beam trigger demand data and the timestamped digital data for the input signals and output a three-dimensional spatial characterization and a fluence characterization of an incident beam.

37. A method for characterizing a hadronic or ionic beam, comprising: placing a detector on a patient support system; positioning the detector on the patient support system so that a detection portion of the detector is disposed transverse to a direction of expected travel of a beam; imaging the detector with an x-ray to locate one or more fiducials within the detector; adjusting the position of the detector or adjusting the position of the patient support system to place the one or more fiducials in an expected position;activating the beam, wherein, on activation, the beam is incident on the detection portion of the detector; recording the signals resulting from ionization events to obtain recorded signal data, the signals being generated on a plurality of detector strips in an x- position layer of the detection portion and on a plurality of detector strips in a y- position layer of the detection portion, the recorded signal data associating a magnitude of each signal with a specific detector strip; timestamping the recorded signal data to obtain timestamped signal data; receiving beam trigger demand data comprising timestamped data corresponding to the energy of the beam at each timestamp; associating the timestamped signal data with the beam trigger demand data; and determining, based on the associated timestamped signal data and beam trigger demand data, a three-dimensional position of the beam at each time.

38. The method of claim 37, wherein the step of recording the signals resulting from ionization events further comprises recording the signals generated from an intensity layer of the detection portion.

39. The method of claim 38, further comprising displaying a report comprising a three- dimensional spatial and fluence characterization of the beam.

40. The method of claim 39, further comprising adjusting a treatment plan based at least in part on the displayed report.

41. The method of claim 37, wherein the three-dimensional position of the beam at each time is determined without further adjusting the position of the detector the patient support system.

42. The method of claim 37, wherein the activation of the beam executes a complete patient treatment plan, and wherein the three-dimensional position of the beam is determined without pausing the activation of the beam during the patient treatment plan.

43. The method of claim 37, wherein the beam is a proton beam.

44. The method of claim 37, wherein the beam is a helium beam.

45. The method of claim 37, wherein the beam is a carbon beam.

46. The method of claim 37, wherein the beam is a hadronic beam.

47. The method of claim 37, wherein the beam is a heavy ion beam.

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