Cherenkov radiation beam monitor

Abstract

Beam calibration instrument and method are provided to calibrate radiotherapy beams (including but not limited to the FRASH-RT beams) used in radiotherapy oncology treatment programs based on the detection of Cherenkov light generated in a plastic material. The calibration instrument may comprise a monitor body and a radiation beam source configured to emit a beam into the monitor body. The beam is configured to interact with a material of monitor body to release Cherenkov radiation within the monitor body. The calibration instrument further includes a detector configured to detect the Cherenkov radiation, and a detection system configured to determining a characteristic associated with the calibration beam. The detector is coupled to the monitor body.

Description

CHERENKOV RADIATION BEAM MONITORCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims benefit under 35 USC§ 119(e) to U.S. Provisional Patent Application No. 63 / 572,025 filed March 29, 2024 and entitled "Cherenkov-Based Radiation Beam Monitor", the disclosure of which is incorporated by reference herein in its entirety7for all purposes.GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with Government support under Grant No. EB029533, awarded by the National Institutes of Health. The Government has certain rights in the invention.TECHNICAL FIELD

[0003] The present disclosure relates generally to radiotherapy and, more particularly (although not necessarily exclusively), to a radiotherapy beam calibration device and techniques for detecting Cherenkov radiation generated in a plastic material.BACKGROUND

[0004] Cancer therapy using external beam radiation constitutes a high percentage of the oncologic treatments. Conventional radiotherapy consists of beams of high energy X-rays or electrons that are used for imaging. During the last decade, radiotherapy using protons has become popular and growing in use. X-ray radiotherapy typically may use photons, particles with no charge and no mass, with energies up to 18 MeV. Electrons are particles with charge, typically denoted by a negative charge “-1 e”, and a mass of 0.5 MeV / c2, with c being the speed of light. In contrast, protons are particles with charge, “+1 e”, and mass of 1000 MeV / c2. For both electrons and protons, the charged particles, there is another radiotherapy modality called flash radiotherapy, also called 'FLASH ' or "FLASH-RT ". which uses extremely high fluxes of particles over very short periods of time for imaging. The physical differences between beams of photons, electrons, and protons, as well as the different beam intensities among modalities impose severe limitations in instruments used to calibrate the beams.

[0005] The gold standard of radiotherapy beam calibration uses ionization chambers to measure a dose deposited. These chambers may typically have a volume of ~0.6 cubiccentimeters. However, responses of ionization chambers may not be linear with dose rate and may need a calibration factor. In addition, the response may be dependent on beam dose and often saturates significantly below the beam intensity of FLASH. Moreover, ionization chambers also need calibration adjustments to account for pressure and temperature differences thus significantly increasing the complexity and factors involved in FLASH beam calibration.

[0006] Embodiments address these and other problems, individually or collectively.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 depicts an example Cherenkov radiation beam monitor utilizing a photon beam, according to various embodiments.

[0008] FIG. 2 depicts an example Cherenkov radiation beam monitor utilizing a charged particle beam, according to various embodiments.

[0009] FIG. 3 depicts an example configuration for a Cherenkov beam monitor, according to various embodiments.

[0010] FIGS. 4A-4C depict example Cherenkov radiation beam responses for several targets using a photon beam, according to various embodiments.

[0011] FIG. 5A-5C depict example Cherenkov radiation beam responses for several targets using charged particle beams, according to various embodiments.

[0012] FIG. 6 illustrates an exemplary flowchart for detecting and analyzing a Cherenkov radiation, according to various embodiments.SUMMARY

[0013] Cherenkov light may be generated in a material by a charged particle traveling at very high-speed through the material. Electron and protons beams may induce Cherenkov tight directly by traveling at velocities greater than the speed of tight in the material. For beams with photons (e.g., light), secondary electrons may be created by an interaction of photons with the material (e.g., plastic) to emit Cherenkov light.

[0014] Various embodiments provide a method for radiotherapy beam calibration. The method may include emitting a beam from a radiation beam source, receiving the beam within a monitor body, wherein the beam interacts with a material of the monitor body toemit Cherenkov radiation within the monitor body, detecting the Cherenkov radiation emitted within the monitor body at a detector coupled to the monitor body, and determining a value of a characteristic associated with the beam based at least in part on the Cherenkov radiation detected at the detector.

[0015] Various embodiments provide an apparatus comprising a monitor body, a radiation beam source configured to emit a beam into the monitor body, wherein the beam is configured to interact with a material of monitor body to release Cherenkov radiation within the monitor body, a detector configured to detect the Cherenkov radiation, wherein the detector is coupled to the monitor body, and a detection system configured to analyze the Cherenkov radiation and determine a characteristic associated with the beam based at least in part on an analysis of the Cherenkov radiation.

[0016] Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Neither this summary nor the following detailed description purports to define or limit the scope of the inventive subject matter.DETAILED DESCRIPTION

[0017] In the following detailed description, various examples will be described in detail. For purposes of explanation, specific methods, systems, device, and process are described in order to provide an in-depth understanding of the examples. It will be appreciated that the system described in the embodiments may vary as to configuration and as to details of the parts, and that the method may vary as to the specific steps and sequence, without departing from the basic concepts as disclosed herein.

[0018] Radiotherapy is one of the main options available for cancer treatment depending on the tumor location, staging of the disease, or condition of the patient. The settings of the radiotherapy beams used in radiotherapy can vary dramatically. The radiotherapy beams can include different particles (e.g., photons, electrons, or protons). In practice, these particles may be accelerated to different energies, and the flux (or number of particles per time and surface area) can vary several orders of magnitude. The radiation detectors used routinely for beam calibrations show very different responses for different beam conditions such that correction factors need to be applied depending on the various operational parameters, ultimately increasing the uncertainty of the beam measurement.[00191 Embodiments provide a Cherenkov beam monitor (also referred as “apparatus”, “instrument”, “device”) to calibrate radiotherapy beams used in radiotherapy oncology treatment programs. According to various embodiments, a Cherenkov beam monitor may be physically robust, minimize calibration factors, and provide compatibility with beams with different particles (e.g., photons, protons, ions, etc.).

[0020] Conventional detectors currently used to calibrate beams utilize costly and complex ionization chambers. Due to physical properties of the ionization chamber (e.g., gas used in the chamber, saturation threshold, etc.), frequent and timely corrections for temperature and pressure must be performed, as well as determining a calibration factor to account for the difference between gas (the substance used to detect radiation) and human tissue which can be approximated as water in radiotherapy applications. Calculating calibration factors for ionization chambers in FLASH-RT can be challenging and time consuming due to the nonlinear chamber behavior at ultra-high dose rates, energy dependencies, environmental factors, transient pulse durations, and the experimental nature of FLASH-RT. Overcoming these challenges needs complicated experimental setups, sophisticated mathematical models, and potentially new ionization chamber designs optimized for FLASH-RT applications. Addressing these difficulties may be necessary for ensuring accurate and reliable dosimetry in this emerging radiotherapy technique. Due to these difficulties, there is a need for a method to calibrate radiotherapy beam sources without considering calibration factors entirely.

[0021] According to various embodiments, Cherenkov light may be emitted within a material (water equivalent detector material such as plastic) to be used as a radiation detection mechanism. In photon-based beams, secondary electrons (e.g., recoil electrons) generated by the photons may emit Cherenkov light within the material. In electron and proton beams, the electrons and protons may directly generate Cherenkov light in the material. The Cherenkov beam monitor provides several advantages compared to conventional detectors for beam calibration. The Cherenkov beam monitor may use a solid material such as a polymer (e.g.. plastic). Using polymers may eliminate the need to calibrate the radiotherapy beam for temperature and pressure changes, which are often frequent within clinical buildings. By way of example, a calibration factor does not need to be calculated or applied as plastic is already considered to be water equivalent (e.g., tissue equivalent) in dosimetry applications. The Cherenkov light may be detected using any suitable light powersensor (e.g., photodiode detector), thereby eliminating dedicated readout electronics that can easily increase production costs with more individualized detectors.

[0022] An intensity of Cherenkov light is inherently low, which allows the Cherenkov beam monitor to be used in FLASH radiotherapy (FLASH-RT), where radiation doses are ten to one hundred fold greater than conventional ionization chamber radiotherapy techniques. FLASH-RT dosages can be delivered at rates between forty and one hundred Gy / second or higher. In some examples, the dose rate can be sixty Gy / second or higher. FLASH-RT may be delivered in single-fraction doses to minimize normal tissue damage. For single-fraction doses, the dose rates may be between ten to twenty for a session (e.g., a treatment session). The Cherenkov light with low intensity may allow a signal processor to measure currents with small fluxes, ultimately offering a wide dynamic range of readouts. In some embodiment, a strong linear response over three orders of magnitude may be detected by the photosensor.1. Example Cherenkov Radiation Beam Monitoring Devices i. Photon source Cherenkov Beam Monitor

[0023] FIG. 1 depicts an example Cherenkov radiation beam monitor 100 utilizing a photon beam, according to some embodiments. The Cherenkov beam monitor 100 includes a photon source 102. a monitor body 106, and a detector such as photosensor 112 (e.g., Thorlabs S120VC photodiode) coupled to the monitor body 106. In a non-limiting example, the monitor body 106 may include a material made out of a polymer, composite, or a similar material. The polymer may include, without limitation, poly(methylmethacrylate) (PMMA), polyethylene, or suitable equivalents. In some examples, the monitor body 106 may include water housed within. Composite materials can include, without limitation, titanium dioxide doped polymers, lead glass, and / or nanostructured ceramics. The monitor body 106 may be transparent to one or more wavelengths (e.g., between three hundred and fifty nm and six hundred nm).

[0024] In some embodiments, the photosensor 112 may be provided along a surface or a side of the monitor body 106. The photosensor 112 may be in direct physical contact with the monitor body 106 or may be located at a position near the monitor body 106 (e.g., not in direct contact) that is capable of detecting the Cherenkov radiation 110. The photon source 102 emits a photon beam 104 (shown in dashed lines) tow ards the monitor body 106 to generate Cherenkov light. While the photon beam 104 is shown as an expanding lightenvelope, the photon beam 104 may be any suitable shape (e.g., collimated light) to irradiate the monitor body 106.

[0025] The material of the monitor body 106 may interact with the photon beam 104 to generate one or more ejected electron(s) 108 (e.g., secondary electrons). The ejected electron(s) 108 may be generated by way of effects such as Compton scattering, the photoelectric effect, and / or pair production. The ejected electron(s) 108 may travel along a trajectory 114 within the monitor body 106 which subsequently produces Cherenkov radiation 110 along the trajectory 114. While the trajectory 114 is shown as a linear path forward for clarity of discussion, it should not be considered limiting, and one skilled in the art would recognize that interactions of the photon beam 104 with electrons will cause numerous trajectories at various angles within the monitor body 106. When the ejected electron(s) 108 travel through the monitor body 106 at a speed greater than the phase velocity of light in the same material within the monitor body 106, Cherenkov radiation 110 is created / released within the monitor body 106 as well. The released Cherenkov radiation 110 is then detected photosensor 112.

[0026] The Cherenkov beam monitor 100 may be used to acquire data (e.g., dosage data) using the combination of the monitor body 106 and photosensor 112. The monitor body 106 may be any suitable shape. The shape of the monitor body 106 may include, without limitation, cylindrical shapes, rectangular shapes, triangular shapes, polyhedron, or combinations thereof. In a non-limiting example, the monitor body 106 may be a cylindrical rod with a nine millimeter (mm) diameter and an eight centimeter (cm) length. In some examples, the monitor body 106 may be encapsulated or otherwise shielded from ambient light. The encapsulation can include, without limitation, a tape, a coating, a resin, an encapsulation, a housing, a cap (e.g., attachable shape fitting cover), or combinations thereof that are configured to block at least one wavelength of light (e.g., between two hundred nanometers (nm) and seven hundred nm). In some examples, the tape may be opaque (e.g., black tape) or may be reflective (e.g., single sided reflective, double sided reflective, etc.).

[0027] The photosensor 112 may be in communication with a detection system 120 which may include numerous components. For example, the detection system 120 may include one or more processor(s) 122, at least one memoty 124, and one or more input / output (I / O) devices 126. The processor(s) 122 may function to receive a signal from the photosensor 112 and process the signal to determine an intensity of Cherenkov radiation 110 within themonitor body 106. I / O devices may facilitate precise delivery and monitoring of radiation treatment including calibration methods (as discussed in more detail with respect to FIG. 6). I / O devices may include imaging systems, (e.g., as CT or MRI scanners), which capture detailed anatomical data for treatment planning, and sensors that detect positioning and motion. Output devices include linear accelerators (LINACs) and proton beam systems that deliver therapeutic radiation doses to target tissues with high precision, guided by real-time imaging feedback. Displays, such as computer monitors, output present treatment plans, dose distributions, and patient data.

[0028] By way of a non-limiting example, a user (or machine) may desire to calibrate a radiotherapy device using the Cherenkov beam monitor 100. The monitor body 106 (coupled to the photosensor 112) may be positioned and aligned within a region of interrogation by photon source 102. The photon source 102 may emit the photon beam 104 (e.g., X-rays, Gamma Rays, etc.) into the monitor body 106. The photon beam 104 may have a wavelength between 0.001 nm to around one nm. These wavelengths correspond to the high photon energies used to eject secondary electrons in the monitor body 106. Once the photon beam 104 has produced ejected electron(s) 108, the photosensor 112 may begin to collect signals associated with the Cherenkov radiation 110 produced by the ejected electron(s) 108. The photosensor 112 may relay the signal to the processors) 122 for processing to determine one or more dosages (e.g., Gy, Sv. Rad, etc.) associated with an intensity and / or frequency of the photon beam 104. The dosages may be stored in memory 124 for later retrieval and / or display / interaction on the I / O devices 126 (e.g., graphical user interface (GUI), computer, etc.). The detection system 120 may be local to the Cherenkov beam monitor. ii. Charged Particle Source Cherenkov Beam Monitor

[0029] FIG. 2 depicts an example Cherenkov radiation beam monitor 200 utilizing a charged particle beam, according to some embodiments. The Cherenkov radiation beam monitor 200 differs from the Cherenkov radiation beam monitor 100 in that the Cherenkov radiation beam monitor 200 uses a charged particle source 202 rather than a photon source to induce Cherenkov radiation 210 in the monitor body 206. The Cherenkov radiation beam monitor 200 may include a charged particle source 202, a monitor body 206, and a photosensor 212 coupled to the monitor body 206. The monitor body 206 and / or photosensor 212 are examples of monitor body 106 and / or photosensor 112 with respect to FIG. 1. The charged particle source 202 may emit a charged particle beam (e.g., electrons, protons, ions,or suitable equivalents) towards and into the monitor body 206 along a trajectory 214 to generate Cherenkov light. The material of the monitor body 206 may interact with the charged particle beam 204 to generate Cherenkov radiation for detection by the photosensor 212. When the charged particle beam 204 travels through the monitor body 206 at a speed greater than the phase velocity of light in the monitor body 206 within the monitor body 206, Cherenkov radiation 210 is created / released within the monitor body 206 as well. The released Cherenkov radiation 210 is then detected by the photosensor 212.

[0030] FIG. 3 depicts an example configuration for a Cherenkov beam monitor 300, according to some embodiments. The Cherenkov beam monitor 300 may include a support 302 capable of supporting a photosensor 304 (which is an example of photosensor 112 with respect to FIG. 1) and a monitor body 306 (which is an example of monitor body 106 with respect to FIG. 1). The support 302 may be an articulating arm that may be configured to provide six-degrees of rotation and three-degrees of translation for positioning the monitor body 306 in line with a beam 310 (e.g., photon beam 104 with respect to FIG. 1 or charged particle beam 204 with respect FIG. 2) generated by beam source 308 (e.g., photon source 102 with respect to FIG. 1 or charged particle source 202 with respect to FIG. 2). As discussed in FIGS 1 and 2, the monitor body 306 may interact with the beam 310 to produce Cherenkov radiation which may be detected by photosensor 304 and relayed to detection system 320 (which is an example of detection system 120 described above with respect to FIG. 1) by way of a communication line 322.2 Results i. Results using a Photon source to Induce Cherenkov Radiation

[0031] FIGS. 4A-4C depict an example Cherenkov radiation beam responses for several targets using a photon beam, according to some embodiments. The charts shown in FIGS. 4A-4C depict irradiance vs dose rate using the photon beam with various filters and one hundred MU intensity. The response data was acquired using the same photosensor, at the same location and the same beam conditions. The experiment w as performed using three different filters: six 6FFF, 10 FFF. and 18F. illustrated in FIGs. 4A-4C. respectively. The target treatment area (e.g., the monitor body 106 described above with respect to FIG. 1) was exposed to a photon beam with different targets and filters (6FFF, 10FFF, and 18F). For example, the beam conditions may include the same radiation dose that will be administered to a target treatment area (e.g.. one hundred monitoring units (MU)) and the target treatmentarea (e.g., the monitor body 106 of size 2x2 cm). The charts 400A-400C show a response as a function of dose rate against irradiance in watts per square cm (W / cm2).

[0032] In chart 400A in FIG. 4 A, a dose rate was measured (e.g., using detection system 120 shown in FIG. 1) using the Cherenkov beam monitor of FIG. 1. Chart 400A shows high linearity with an R2value of 0.99985 with a ninety-five percent confidence interval for a 6FFF target with a 2x2 cm monitor body size and one hundred MU intensity. High linearity means that there is a linear relationship between irradiance of the Cherenkov radiation and the dose rate. If two or more irradiance values are calculated for given dose rates, other irradiance values along the same line may be determined without performing additional experiments as all irradiance values will fall on the same line given associated dose rates (and vice-versa).

[0033] In chart 400B in FIG. 4B, a dose rate was measured using the Cherenkov beam monitor. Chart 400B shows high linearity with an R2value of 0.999911 with a ninety- five percent confidence interval for a 10FFF target with a 2x2 cm monitor body size and one hundred MU intensity.

[0034] In chart 400C in FIG. 4C, a dose rate was measured using the Cherenkov beam monitor. Chart 400C shows high linearity with an R2value of 0.999997 with a ninety-five percent confidence interval for a 18F target with a 2x2 cm monitor body size and one hundred MU intensity. No signs of saturation were detected at the highest dose rates. A high linearity of the response makes the beam monitor readily calibratable. For example, accurate dose rates were detected in all instances since generation and collection of Cherenkov radiation is proportional to an incident number of particles and / or electron ejections within the monitor body, which leads to the high linearity of the response. ii. Results using a Charged Particle Source to Induce Cherenkov Radiation

[0035] FIGS. 5A-5C depict example Cherenkov radiation beam responses for several targets using a charged particle beam, according to some embodiments. The charts shown in FIGS. 5A-5C depict MU vs irradiance using the charged particle beam. The charts shown in FIGS. 5A-5C depict irradiance against MU using the charged particle beam. Data was acquired for seven different MU scenarios between 0.26 MU and sixteen MU. The charged particles are injected into a monitor body (e.g., monitor body 206) at an energy of twenty hundred and twenty-seven Mev.[00361 Chart 500A depicts a detector response for these seven points, shown along the linear line. Not depicted in chart 500 A, an eighth point was acquired at 2000 MU, which is shown at an extremity in the top right of the chart 500B. Chart 500 A depicts a detector response for these eight points, shown along the linear line, concentrated at the extremities.

[0037] Chart 500B represents (e.g., due to scaling in MU, the seven data points for the chart 500A are concentrated around (0,0)) plus an additional point at 2000 MU. The spot size for a target treatment area such as a monitor body (e.g., monitor body 206 shown in FIG. 2) as around 1x1 mm2.

[0038] Chart 500C includes the same data in the chart 500A in log scale to demonstrate the behavior of the photosensor across different orders of magnitude. The relevant outcomes of these measurements include: high linearity in all cases with good R2values and 95% confidence interval, wide dynamic range across three orders of magnitude, and no signs of saturation at the highest dose rate (e.g., 2000 MU).3. Illustrative Methods for Calibrating Radiotherapy Devices i. Example Calibration of Beam Source

[0039] Calibrating a radiotherapy device using Cherenkov radiation to determine dose rates to be applied to a tissue of an organism (e.g., a patient) may leverage the high linearity of an irradiance response of a monitor body producing Cherenkov radiation, as discussed in FIGS. 4A-4C and FIGS. 5A-5C. A monitor body (e.g.. monitor body 106 / 206 of FIGS. 1 or 2) may be positioned (e.g.. using support 302 with respect to FIG. 3) in alignment with a beam source (e.g., photon beam source or charged particle beam source) to receive a dose of radiation from the beam source. The monitor body may receive the beam and generate Cherenkov radiation. Cherenkov radiation signal may be captured by a photosensor (e.g., photosensor 304 with respect to FIG. 3) substantially in real-time.

[0040] By way of a non-limiting example, an intensity (or irradiance) of the Cherenkov radiation emitted from the monitor body can be detected by integrating the detected intensity of the Cherenkov radiation over time. Again, due to the high linearity of the response as discussed in FIGS. 4A-4C and FIGS. 5A-5C, a characteristic of the beam (e.g., dose rate) can be determined by determining the irradiance measure for either a photon beam source or a charged particle beam source (e.g., electron beam source, proton beam source). For example, and referring to chart 400A of FIG. 4A or a photon beam source, a measured irradiance fromthe photosensor of 1.0 W / cm2would yield a dose rate around 1000 Gy / s without needing to calculate a calibration factor. A user (or machine) may then calibrate the beam source to an appropriate dose rate based at least in part on the measured irradiance. ii. Example Calibration Methods

[0041] FIG. 6 depicts a block diagram illustrating an example method 600 of calibrating a radiation beam using Cherenkov radiation emissions, in accordance with some embodiments. The method 600 may be performed by a Cherenkov beam monitor described herein and one or more computer implementations. By way of example, the method 600 may include more or fewer steps than the number depicted in FIG 6.

[0042] At block 602, a radiation beam source (e.g., photon source 102 with respect to FIG. 1 or charged particle source 202 with respect to FIG. 2) may emit a beam (e.g., protons, photons, etc.). The beam may have a predetermined known intensity (or may be unknown) and be dynamically adjusted by a user (or machine) by one or more lensing or filter components placed after the source. In some examples, the beam may be pulsed or continuous. In some examples, the beam is a high dose radiation FLASH-RT beam (e.g., forty to one hundred Gy / second or higher).

[0043] At block 604, a monitor body (e.g., monitor body 306 shown in FIG. 3) may receive the beam within. In some examples, the beam is a charged particle beam (as in FIG. 2) that may propagate through some or all of the monitor body. In other examples, the beam is a photon beam (as in FIG. 1) that may interact with electrons w ithin the monitor body causing various interactions (e.g., ejected electrons) as the photons traverse the monitor body. In some examples, the monitor body is at least partially surrounded by one or more of: a light blocking tape, a light blocking coating, or light blocking resin, a light blocking encapsulation, a light blocking housing, or a combination thereof. In various examples, the monitor body may be cylindrical in shape.

[0044] At block 606, a detector (e.g., photosensor 304 with respect to FIG. 3) may detect the Cherenkov radiation emitted within the monitor body. Cherenkov radiation emissions radiate within the monitor body as a result of interactions between the beam and the material of the monitor body. In some examples, the beam may cause secondary' electron emissions within the monitor body causing Cherenkov radiation emissions. In other examples, the calibration beam may be pulsed or continuous in order to generate an appropriate Cherenkov emission response.

[0045] At block 608, a value (e.g.. irradiance) of a characteristic (e.g., dose rate) associated with the beam may be determined based at least in part on the Cherenkov radiation detected at the detector. The detector coupled to the monitor body may detect the Cherenkov radiation within the monitor body substantially simultaneously as the calibration beam transmits through the monitor body. In some examples, the detector may be in direct physical contact with the monitor body that generates the Cherenkov radiation. In other examples, the detector may be in close proximity to the monitor body. In a non-limiting example, the characteristic may be calibrated (e.g., adjust the dose rate) based at least in part on the value of the characteristic (as discussed in more detail with respect to FIGS. 4A-5C).

[0046] For example, the Cherenkov beam monitor may include a detection system configured to determining the characteristic associated with the calibration beam. In some embodiments, the detection system may include a computation device coupled to the detector of the Cherenkov beam monitor. For example, the computation device may include one or more processors; and one or more memories storing computer-executable instructions that, when executed by the one or more processors, cause the one or more processors to determine the characteristic associated with the calibration beam. The computer-executable instructions further causes the one or more processors to: identify operation settings including one or more of: a type of the radiation beam source, a type of the material, an intensify of the radiation beam source; retrieve one or more historical characteristics (dose rates and / or irradiance values as in FIGS. 4A-5C) from a database; compare the one or more historical characteristics to the characteristic associated with the calibration beam; and in response to determining a match between the one or more historical characteristics (e.g., previously calculated values along the linear response slope) and the characteristic associated with the calibration beam, store the characteristic associated with the calibration beam in the look-up table along with the operation settings that were identified.

[0047] According to various embodiments, the emission of Cherenkov light in the material provides significant improvements compared to ionization chambers. Response information in ionization chambers may typically be provided by a charge collection information. On the other hand, in the Cherenkov beam monitor, the response information is provided by visible Cherenkov light. Unlike with the charge collection information, generation and collection of Cherenkov light is proportional to an incident number of charged particles and highly efficient, thereby leading to a very high linearity in the detector response. The Cherenkov beam monitor may additionally provide a reliable signal at FLASH beams, whereas theionization chambers are known to saturate at FLASH beams. The limitations in generation and collection of charges discussed above with respect to the ionization chambers may limit maximum doses that the ionization chambers may detect. In addition, photodetectors of exemplary Cherenkov beam monitors described herein may allow measurements of very low and very high pulses of light with relatively cheap materials. Solid detectors for calibration of external radiation sources exist, including diodes. Diodes, however, have known stability issues and are used only for relative (e.g., not absolute) measurements. In addition, the Cherenkov beam monitor described herein does not need pressure or temperature corrections which may be required in ionization chambers since ionization chambers typically contain a gas media during calibration processes. Embodiments described above can use plastic or similar polymer materials that does not require the use of the gas media, thereby minimize measurement uncertainty.

[0048] Specific details regarding some of the above-described aspects are provided above. The specific details of the specific aspects may be combined in any suitable manner without departing from the spirit and scope of embodiments.

[0049] Storage media and computer readable media for containing code, or portions of code, may include any appropriate media known or used in the art, including storage media and communication media, such as but not limited to volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage and / or transmission of information such as computer readable instructions, data structures, program modules, or other data, including RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, data signals, data transmissions, or any other medium which may be used to store or transmit the desired information and which may be accessed by the computer. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art may appreciate other ways and / or methods to implement the various embodiments.

[0050] It may be understood that aspects of embodiments as described above may be implemented in the form of control logic using computer software in a modular or integrated manner. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art may know and appreciate other ways and / or methods to implement embodiments using hardware and a combination of hardware and software.[00511 Any of the software components or functions described in this application, may be implemented as software code to be executed by one or more processors and or co-processors using any suitable computer language such as, for example, Java, C++ or Perl using, for example, conventional or object-oriented techniques. The software code may be stored as a series of instructions, or commands on a computer readable medium, such as a randomaccess memory (RAM), a read only memory (ROM), a magnetic medium such as a harddrive or a floppy disk, a solid state hard drive, or an optical medium such as a CD-ROM. Any such computer readable medium may reside on or within a single computational apparatus, and may be present on or within different computational apparatuses within a system or network. The use of web-based software for analysis is also explicitly included in this description.

[0052] The above description is illustrative and is not restrictive. Many variations of the embodiments may become apparent to those skilled in the art upon review of the disclosure. The scope of the embodiments may, therefore, be determined not with reference to the above description, but instead may be determined with reference to the pending claims along with their full scope or equivalents.

[0053] One or more features from any embodiment may be combined with one or more features of any other embodiment without departing from the scope of the embodiments.

[0054] A recitation of “a”, “an” or “the” is intended to mean “one or more” unless specifically indicated to the contrary.

Claims

CLAIMS:What is claimed is:

1. A method for radiotherapy beam calibration, the method comprising: emitting a beam from a radiation beam source; receiving the beam within a monitor body, wherein the beam interacts with a material of the monitor body to emit Cherenkov radiation within the monitor body: detecting the Cherenkov radiation emitted within the monitor body at a detector coupled to the monitor body; and determining a value of a characteristic associated with the beam based at least in part on the Cherenkov radiation detected at the detector.

2. The method of claim 1, further comprising: calibrating the radiation beam source to adjust the characteristic associated with the beam based at least in part on the value of the characteristic.

3. The method of claim 2, wherein the radiation beam source is calibrated without calculating a calibration factor.

4. The method of claim 1. wherein the beam is a high dose radiation FLASH-RT beam; and wherein the characteristic associated with the beam is a dose rate.

5. The method of claim 1. wherein the material of the monitor body comprises one or more of: a plastic, a polymer, a composite, or water.

6. The method of claim 1, wherein the radiation beam source is one or more of: a proton beam source, an electron beam source, a photon beam source, or an ion beam source.

7. The method of claim 1, wherein the material of the monitor body is at least partially surrounded by one or more of: a light blocking tape, a light blocking coating, a light blocking resin, a light blocking encapsulation, or a light blocking housing.

8. The method of claim 1, wherein the monitor body is substantially cylindrical and is in direct physical contact with at least a portion of the detector.

9. An apparatus comprising: a monitor body; a radiation beam source configured to emit a beam into the monitor body, wherein the beam is configured to interact with a material of monitor body to release Cherenkov radiation within the monitor body; a detector configured to detect the Cherenkov radiation, wherein the detector is coupled to the monitor body; and a detection system configured to analyze the Cherenkov radiation and determine a characteristic associated with the beam based at least in part on an analysis of the Cherenkov radiation.

10. The apparatus of claim 9, wherein the detection system comprises one or more processors; and one or more memories storing computer-executable instructions that, when executed by the one or more processors, cause the one or more processors to analyze the Cherenkov radiation and determine the characteristic associated with the beam based at least in part on the analysis of the Cherenkov radiation.

11. The apparatus of claim 10, wherein the analysis of the Cherenkov radiation includes determining an irradiance of the Cherenkov radiation within the monitor body.

12. The apparatus of claim 9. wherein the beam is a high dose radiation FLASH-RT beam; and wherein the characteristic associated with the beam is a dose rate.

13. The apparatus of claim 9. wherein the material of the monitor body comprises one or more of: a plastic, a polymer, a composite, or water.

14. The apparatus of claim 9, wherein the radiation beam source is one or more of: a proton beam source, an electron beam source, a photon beam source, or an ion beam source.

15. The apparatus of claim 9, wherein the material of the monitor body is at least partially surrounded by one or more of: a light blocking tape, a light blocking coating, or light blocking resin, a light blocking encapsulation, or a light blocking housing.

16. The apparatus of claim 9, wherein the monitor body is substantially cylindrical.

17. The apparatus of claim 9. wherein the monitor body is in direct physical contact with at least a portion of the detector.

18. The apparatus of claim 9, wherein the detector comprises a photosensor.

19. The apparatus of claim 9, wherein the detection system is further configured to calibrate the radiation beam source to adjust the characteristic associated with the beam based on a value of the characteristic.

20. The apparatus of claim 19, wherein the radiation beam source is calibrated without calculating a calibration factor.

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