System and methods for dose and dose rate control in electron flash platforms

Abstract

A treatment planning tool to automate the optimization of parameters to achieve the intended dose and dose rate available using Ultra-High Dose Rate (UHDR) pulsed electron accelerators. Aspects of the disclosure provide a tool that makes the search of optimal machine parameters less burdensome and eliminate potential user errors by automating this process. Commercial electron FLASH platforms deliver UHDR doses at discrete combinations of pulse parameters including pulse width (PW), pulse repetition frequency (PRF) and number of pulses (N), which dictate unique combinations of dose and dose rates. Additionally, collimation, source to surface distance (SSD), and airgaps also vary the dose per pulse. The present disclosure presents a pulse parameter optimizer application to match intended dose and dose rate precisely and efficiently.

Description

SYSTEM AND METHODS FOR DOSE AND DOSE RATE CONTROL INELECTRON FLASH PLATFORMSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 520,970, filed August 22, 2023, entitled “SYSTEM AND METHODS FOR DOSE AND DOSE RATE CONTROL IN ELECTRON FLASH PLATFORMS,” which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Ultra-high dose rate (UHDR) radiotherapy delivers treatment in millisecond timescales. Multiple pre-clinical models including humans, mice, zebrafish, cats, and pigs, have shown decreased side effects on healthy tissues, when compared to conventional dose rates delivered in minutes. Tumor control studies with various tumor types have shown equivalent control with conventional and UHDR irradiation. This biological phenomenon of reducing normal tissue toxicity while maintaining isoeffective tumor control has been called the FLASH effect.

[0003] From a treatment planning and prescription perspective, unlike conventional radiotherapy specifying dose, FLASH RT considers dose rate as an additional variable. The FLASH effect has been largely seen at > 10 Gy total dose and > 40 Gy / s dose rates. However, this phenomenon does not have a binary nature, as varying magnitudes of the FLASH effect have been reported with increasing dose rate, and it may also be dependent on beam-specific pulse parameters. As more commercial platforms for UHDR production emerge for exploration of FLASH RT, it is important for pre-clinical studies to replicate the dose and dose rate combinations that have produced the FLASH effect and further explore in this space to increase magnitude of the effect.

[0004] Electron UHDR platforms, such as the Oriatron eRT6, Kinetron, IntraOp Mobetron, and converted linacs, allow for manual settings of certain pulse parameters including pulse width (PW), pulse repetition frequency (PRE), grid tension, number of pulses (N), etc., to modify dose per pulse and dose rate. FIG. 1 illustrates an ideal pulsed FLASH beam, where the width of an individual pulse is the pulse width, and the frequency of pulses is the pulse repetitionfrequency. Attaining specific combinations of dose and dose rate is not trivial as these two factors become interdependent when the electron pulse structure is modified. The Mobetron (IntraOp, Sunnyvale, CA, USA) has been used for pre-clinical FLASH studies. UHDR delivery requires manual settings of PW, PRF, and N available through discrete settings on dials, which manipulate the dose per pulse (DPP), dose rate, and total dose. Changing the source to surface distance (SSD) will also change the dose per pulse, total dose, and dose rate. Since the settings available for these parameters are limited and discrete, one can only achieve certain combinations of dose and dose rates. This creates an optimization problem to match the intended dose and dose rate for treatment with what is achievable through the machine variables for a particular treatment configuration.SUMMARY

[0005] The present disclosure presents a treatment planning tool to automate the optimization of parameters to achieve the intended dose and dose rate for use in Ultra-High Dose Rate (UHDR) pulsed electron accelerators. In accordance with an aspect of the disclosure, a method of generating parameters for ultra-high dose rate (UHDR) radiotherapy (RT) is described that includes obtaining desired dose and dose rate values for an UHDR RT procedure; obtaining a cone size value for a UHDR electron linear accelerator for the UHDR RT procedure; generate operating parameters for the UHDR electron linear accelerator based on the desired dose and dose rate values and the cone size value; and displaying the operating parameters in a user interface.

[0006] In accordance with another aspect of the disclosure, a method of operating an ultra-high dose rate (UHDR) radiotherapy (RT) device is described that includes , the method comprising receiving a desired dose and dose rate values for a UHDR RT procedure; receiving a cone size value for a UHDR electron linear accelerator for the UHDR RT procedure; receiving operating parameters for the UHDR electron linear accelerator based on the desired dose and dose rate values and the cone size value; and controlling the UHDR electron linear accelerator according to the operating parameters.

[0007] This summary is provided to introduce a selection of concepts in a simplified form that is further described below in the detailed description. This summary is not intended toidentify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing summary, as well as the following detailed description of illustrative implementations, is better understood when read in conjunction with the appended drawings. To illustrate the implementations, there are shown in the drawings example constructions; however, the implementations are not limited to the specific methods and instrumentalities disclosed. In the drawings:

[0009] FIG. 1 illustrates an ideal pulsed FLASH beam, where the width of an individual pulse is the pulse width and the frequency of pulses is the pulse repetition frequency;

[0010] FIG. 2A illustrates an example configuration of direct mounting of a collimator on the exit window of a gantry in accordance with aspects of the disclosure;

[0011] FIG. 2B illustrates an example configuration that is achieved through an applicator in accordance with aspects of the disclosure;

[0012] FIG. 2C illustrates pulse repetition frequency (PRF) and pulse width (PW) dials to allow pulse parameter manipulation for ultra-high dose rate (UHDR) beams in accordance with aspects of the disclosure;

[0013] FIG. 3 illustrates example dose and dose rate as a function of number of pulses for different pulse widths at a set PRF of 60 Hz in accordance with aspects of the disclosure;

[0014] FIG. 4A shows a fall off for a 6 cm diameter cone in accordance with aspects of the disclosure;

[0015] FIG. 4B shows the dose fall off for a 2.5 cm diameter cone in accordance with aspects of the disclosure; and

[0016] FIG. 5 illustrates an example screen capture of the Pulse Parameter Optimizer graphical user interface (GUI) in accordance with aspects of the disclosure.DETAILED DESCRIPTION

[0017] Overview and Introduction

[0018] The present disclosure presents a treatment planning tool to automate the optimization of parameters to achieve the intended dose and dose rate available using theMobetron. Aspects of the disclosure can be extended to variables available for other Ultra-High Dose Rate (UHDR) pulsed electron accelerators. Aspects of the disclosure provide a tool that makes the search of optimal machine parameters less burdensome and eliminates potential user errors by automating this process.

[0019] Commercial electron FLASH platforms deliver UHDR doses at discrete combinations of pulse parameters including pulse width (PW), pulse repetition frequency (PRF) and number of pulses (N), which dictate unique combinations of dose and dose rates. Additionally, collimation, source to surface distance (SSD), and airgaps also vary the dose per pulse. Currently, obtaining pulse parameters for the desired dose and dose rate is a cumbersome manual process involving creating, updating, and looking up values in large spreadsheets for every treatment configuration. The present disclosure presents a pulse parameter optimizer application to match intended dose and dose rate precisely and efficiently.

[0020] Dose and dose rate calculation methods have been described for a commercial electron FLASH platform. In accordance with the present disclosure, a constrained optimization for the dose and dose rate cost function is modelled as a mixed integer problem in MATLAB (The MathWorks Inc., Version1?.13.0 R2022b, Natick, Massachusetts). The beam and machine data required for the application were acquired using GafChromic film and Alternating Current Current Transformers (ACCTs). Variables for optimization included dose per pulse (DPP) for every collimator, PW and PRF measured using ACCT and airgap factors. Using PW, PRF, N and airgap factors as parameters, software optimizes dose and dose rate, reaching the closest match if exact dose and dose rates are not achievable. Optimization takes 20 seconds or less to converge to results. This software has been validated for accuracy of dose calculation and precision in matching prescribed dose and dose rate.

[0021] A pulse parameter optimization application was built for a commercial electron FLASH platform to increase efficiency in dose, dose rate, and pulse parameter prescription process. Automating this process reduces safety concerns associated with manual look up and calculation of these parameters, especially when many subjects at different doses and dose rates are to be safely managed.

[0022] Exploration of the dose and dose rate space to optimize the FLASH effect is utilized for pre-clinical studies and can guide standardization for future clinical use. Since dose and dose rate are not independent variables for the FLASH Mobetron, there is a need tounderstand what combinations are achievable with all pulse parameters available for guiding the decision-making process for researchers and clinicians. The pulse parameter optimization tool helps navigate multiple variables to achieve the desired dose and dose rates more precisely and efficiently. Since the Mobetron provides upwards of 8 Gy per pulse, errors in pulse parameter calculation could lead to large differences in dose, which is a serious safety concern. Automating this task greatly reduces human error in maintaining spreadsheets and look-up tables for various combinations of pulse parameters for every collimator.

[0023] Aspects of the present disclosure have been developed for Delrin collimators at SSD = 18.3 cm and can be adapted to other geometries with additional beam data. The current version of the optimizer also gives equal weight to all the parameters available, but priorities can be assigned to favor one parameter over another. For instance, dose could be prioritized over dose rate or the pulse width parameter could be locked while varying other parameters.

[0024] The use of distance as an additional variable has been explored in order to achieve finer changes in dose. The effective SSD and gap factor methods as described in AAPM TG-71 are designed for a conventional linac at a much larger SSD (= 100 cm). They use a single dmax value for PDDs across all airgaps for calculation of the effective SSD or gap factors. Since the depth of dmax changed considerably with airgap for smaller fields, collimator specific fits of dose fall off with airgap were obtained instead to avoid the uncertainty in effective SSD calculations. Changing airgap also has implications on beam flatness and field size. Therefore, users should characterize the beam at varying airgaps. This is not trivial for UHDR beams, as ion chambers are not available for beam data acquisition and film is currently the standard commissioning dosimeter. However, irradiating film parallel to the beam direction provided an efficient way for assessment of changes in beam characteristics with distance.

[0025] Dose measurement is limited by uncertainties in film dosimetry and machine output variability. For example, if the Mobetron (intraoperative configuration) does not have an internal optical distance indicator or couch positions, an external laser device pointing towards a fixed spot on the gantry was used to set airgaps. Based on these sources of uncertainties, a cumulative error of 6% may be assigned to dose.

[0026] It should be noted that different versions of the Mobetron may have slightly different configurations for PW, PRF, and collimation. Based on these parameters, there could also be variations in outputs across machines. Therefore, user may characterize the parametersmentioned in Table 3, below, for use with the software. Also of note are potential changes in beam energy with pulse width which need to be characterized by users, where beam energy could decrease with increasing pulse width due to the beam loading effect. The current version of the optimizer also does not account for pulse-to-pulse variations in output, which can amount to up to 6% between the first and subsequent pulses, as reported in. Film dosimetry adds additional uncertainty to all the data, which has been reported up to 4% for EBT3 films between 3 and 17 Gy. With the development of new UHDR-compatible active detectors for beam data collection, this uncertainty may be greatly reduced.

[0027] Example Methods

[0028] Dosimetry is a challenge in the UHDR realm due to increased ion recombination in standard dosimeters such as ion chambers. Film is the standard dosimeter for UHDR beams due to its absence of dose per pulse dependency. Since UHDR mode in the FLASH Mobetron requires manual settings of pulse parameters, these parameters are commissioned and monitored. This can be done by extracting signals from different parts of the accelerator and recording the pulse waveforms with an oscilloscope. Alternating Current Current Transformers (ACCTs) in the head of the Mobetron have shown promise in providing pulse parameter information as well as for real time dosimetry. The present disclosure utilizes EBT-XD GafChromic film (Ashland Advanced Material, NJ, USA) for dose measurements and ACCT measurements for characterizing and reporting of pulse parameters. The following describes dose and dose rate calculation based on machine parameters and the beam data required to run the optimization tool.

[0029] Description of Treatment Configurations and Pulse Parameters

[0030] The FLASH Mobetron 200 in the Intraoperative Radiation Therapy (IORT) configuration has two available SSD configurations for irradiation using collimators made from DELRIN (e.g., polyoxymethylene) material ranging from 2.5 cm to 6 cm in diameter. FIGS. 2A- 2C shows the available SSD configurations. FIG. 2A illustrates an example configuration of SSD of 18.3 cm (204) through direct mounting of the collimator 202 on the exit window of the gantry 208 (“Configuration A”). FIG. 2A also illustrates another example configuration (“Configuration B”) that is achieved through an applicator and provides an SSD of 35 cm (206). SSD configurations have impact not only on the dose per pulse and dose rate, but also on the shape of profiles and Percent Depth Dose (PDD). The present disclosure includes characterization and beam parameter optimization for the SSD = 18.3 cm configuration, to provide a framework thatcan be replicated for other configurations. Beam data was acquired for every collimator at this configuration using EBT-XD GafChromic film.

[0031] All films may be scanned with a glass compression plate using the EPSON 12000XL flatbed scanner (Epson America, Inc., Los Alamitos, CA) at 48-bit color and 75 DPI. Film was calibrated against an ADCL-calibrated farmer chamber with a 9 MeV electron beam from a clinical Varian TrueBeam linac. FilmQA Pro software (Ashland Advanced Material, NJ, USA) was used for film analysis using the triple channel uniformity correction protocol. The RGB values were averaged to calculate dose.

[0032] FIG. 2C illustrates pulse repetition frequency (PRF) and pulse width (PW) dials 240, 242 to allow pulse parameter manipulation for UHDR beams. For example, the Mobetron allows pulse control by manual settings of PRF and PW. While different machines have slightly varying configurations, the Mobetron can be programmed to run with PRFs of 10, 20, 30, 45, and 60 Hz and nominal PWs of 1, 1.6, 2, 3, and 4 microseconds. There are also two ACCTs 222, 224 (Bergoz Instrumentation, France) located in the head of the machine 200, one below the primary scattering foil and the other below the secondary scattering foil (see, FIG. 2B), which produce signal via electromagnetic induction as the electron beam passes through them. A digital oscilloscope (Picoscope 5000, PicoTechnology, UK) may be used to record pulse waveforms and analyze in MATLAB to obtain measured PWs (FWHM of pulses) and area under the pulses (pulse content). The pulse content can be correlated to charge by applying voltage to current conversion coefficients supplied by the vendor.

[0033] Dose and dose rate calculation

[0034] Dose calculation for the FLASH Mobetron is different from standard monitor unit (MU) based dose calculations defined in AAPM TG71. The dose is given by, for example, the following relationship:D (Gy) = N * DPP (60 Hz, 4 ps) * PWF * g (cone, SSD) (1) where D is the total dose, TV is the number of pulses, DPP is the dose per pulse measured at 60 Hz PRF and 4 us PW setting for the cone being used at SSD = 18.3 cm, PWF is a pulse width factor to account for relative differences in DPP between pulse width settings, and g is an airgap dependent factor unique to a particular collimator and configuration. Dose rate is then calculated using:

[0035] Dose per pulse was measured using GafChromic EBT-XD film for each collimator and configurations (SSD 18.3 and 35 cm) at the depth of dmax. The physical pulse widths were measured using the ACCTs at the 50% reference level. Measured PW matched nominal values except for the 4 us setting. It should be noted that these values could vary between machines. Pulse width factors are obtained through film measurements in the same setup, while only varying the nominal PW setting and PRF.

[0036] To characterize dose distributions at airgaps, multiple film measurements parallel to the irradiation beam per collimator were obtained at 1-2 cm increment airgaps up to 10 cm. The parallel film irradiations were performed using a 3D printed vertical film holder that allowed placement of the film level with the surface of the water. A laser distance meter may be used to measure the set airgap between the film / water surface and the collimator. In this way, the dose per pulse, PDDs, and profiles for various airgaps may be obtained with one film measurement per airgap. The doses extracted at dmax were normalized to g = 0 measurement. Doses were then plotted against airgap and fitted with a second order polynomial function with the intercept set to 1 (since at zero airgap, this factor would be 1). For field sizes < 4cm, airgaps < 3 cm were excluded due to considerably decreased therapeutic depth and higher beam horns in the profiles.

[0037] Parameter Optimization

[0038] The FLASH Mobetron delivers the requested number of pulses with the selected pulse repetition frequency and the pulse width. No partial pulse delivery is achievable using the standard commercially provided adjustment dial. These parameters, along with the cone size and the irradiation geometry, determine the dose and dose rates. The objective function is set up to best achieve the desired dose and the dose rates within the parameter space mentioned above as,where D and D are given by equations (1) and (2), subject to the following:PRF e {10,20,30,45,60} Hz, PW e {1,1.6, 2, 3, 4} gs, N l, g e {1 - 100} mm

[0039] The constrained optimization for the objective function was setup as a mixed integer problem in MATLAB since only integer number of pulses could be delivered, and a discrete value of PRF and PWs could be selected by the optimizer while the airgap distancecould be set to a value between 0 and 10 cm. The use of airgap for the optimization is optional. Additionally, PW and PRF can also be fixed at constant values and not be varied for optimization if desired.

[0040] Results

[0041] Beam and pulse parameter dataTable 1 shows the DPP at dmax at PRF = 60 Hz and nominal PW = 4 ps obtained with GafChromic film for different cones. These were acquired at the depth of dmax and airgap of 0 cm for cone sizes > 4 cm, and an airgap of 3 cm otherwise due to unfavorable beam profiles at shorter SSDs and smaller cone sizes (data included in supplementary materials). Three films were irradiated at every setting, and doses extracted were averaged. Table 2 lists the measured pulse widths obtained from ACCT data at the full width at half maximum of a pulse averaged across PRFs, after accounting for the rise time. Film doses were acquired at all combinations of PW and PRFs and were normalized to the 60 Hz and 4 ps setting and averaged across PRFs to obtain PW factors listed in Table 2.Collimator (cm) SSD = 18.3 cm (cGy) Airgap (cm) . 2.5. 771 : 7.72. 3.3 770 ± 6.28 34 735 ± 2.40 35 846 ± 8.62 06 819 ± 4.74 0Table 1: Dose per pulse for circular collimators at SSD Configuration A. PRF = 60 Hz, PW = 4 us. Errors correspond to the standard deviation over three measurements.Nominal Pulse Width Measured Pulse Width (FWHM, ps) Pulse Width Factors1 0.99± 0.02 0.40 ± 0.011.6 1.61 ± 0.02 0.56 ± 0.012 2.02 ± 0.02 0.68 ± 0.013 2.98 ± 0.01 0.93 ± 0.024 3.31 ± 0.00 1.00 ± 0.02Table 2: Measured pulse widths (ACCTs) and relative pulse width factor (obtained from film measurements). Errors correspond to standard deviation over measurements across all PRFs.

[0042] FIG. 3 illustrates example dose (right y axis) and dose rate (left y axis) as a function of number of pulses (x axis) for different pulse widths at a set PRF of 60 Hz. The dose per pulse for a 6cm collimator at SSD Configuration A was used for calculations. Markers represent the discrete values of dose and dose rates that can be achieved. FIG. 3 demonstrates the space of achievable combinations of dose and dose rate as a function of number of pulses and PW at a set PRF of 60 Hz and dose per pulse corresponding to a 6 cm cone in Configuration A. Maximum dose rate that can be achieved in a single pulse delivery is of the order of 106Gy / s, which then drops to 102Gy / s mean dose rates as the number of pulses increases because PRF starts dominating the dose rate calculation.

[0043] Airgap as a Variable

[0044] Film measurements parallel to the beam direction were acquired for every collimator at various airgaps between 0 and 10 cm (0, 0.5, 1, 2, 3, 4, 6, 8, 10 cm) using the vertical film holder apparatus described in the methods. The doses extracted at dinax normalized to either g = 0 or g = 3 cm were plotted against airgap and fitted with a second order polynomial, as shown in FIGS. 4A and 4B for cone sizes of 2.5 cm and 6 cm. FIGS. 4A-4B generally illustrate dose fall off as a function of airgap between the collimator and phantom surface. FIG. 4A shows the fall off for 6 cm diameter cone normalized to the g = 0 maximum dose per pulse along with the corresponding second order polynomial fit. FIG. 4B shows the dose fall off for 2.5 cm diameter cone. The normalizing condition was set at a 3 cm air gap due to unfavorable beam profiles and PDDs at shorter air gaps. Residuals show the percentage differences between the data points and the fits.

[0045] Pulse parameter optimization tool

[0046] A MATLAB-based GUI may be used for the optimizer. The application takes desired dose, dose rate, and cone size as input, and returns number of pulses, pulse width, PRF, and airgap needed to achieve the closest matching dose and dose rate values. It also returns the dose and dose rates achieved through the optimized parameters. Table 3 summarizes the data needed for the optimizer.Beam / Pulse Data DescriptionDose per pulse Measured using GafChromic film for every treatment configurationPulse Widths Pulse Widths measured using ACCT waveformsPulse Width Factors Relative doses with change in pulse width obtained using filmDose fall-off with airgap Dose per pulse fall off with increasing airgap and corresponding beam data to assess changes in PDDs and ProfilesTable 3: Input data needed for Pulse Parameter Optimization

[0047] The optimizer converged to results in 20 seconds or less. The optimization tool was validated for its precision in matching dose and dose rate, and for its accuracy in dose calculation. Precision was tested by using dose and dose rates at set pulse parameter variables from look up tables and performing the optimization for the same input values. The optimizer was able to match the Rx dose and dose rate exactly, and converged to the same pulse parameters that were selected from the look up tables. Airgap was excluded from this analysis since Dpp can be varied using both airgap and PW, which could confound the results. Accuracy was tested by comparing the output dose and dose rates to calculated values from the pulse parameters. Further information can be found in the supplementary materials. Overall, this comparison did not show any deviation beyond rounding errors.

[0048] Quality assurance of the optimizer with known combinations is recommended prior to each use. This MATLAB code is available upon request, but data used to generate the optimization is machine specific.

[0049] FIG. 5 illustrates an example Pulse Parameter Optimizer user interface 500. This example user interface 500 shows a desired dose and dose rate of 10 Gy and 100 Gy / s respectively, with a cone size of 6 cm. The optimization returns 2 pulses, 10 Hz for PRF, 2 ps Nominal PW and 17 mm airgap to achieve the prescribed dose and dose rate.

[0050] Conclusion

[0051] A MATLAB-based pulse parameter optimization software for a commercial platform producing pulsed UHDR electron beams was developed. This tool helps navigate the dose and dose rate space to obtain the best pulse parameters required to achieve the intended dose and dose rate combination. By automating this process, users can more efficiently and precisely match intended dose and dose rate, and greatly reduce human error in manual look up of pulse parameters for calculations.

[0052] The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The implementations of the present disclosure may be realized using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Implementations within the scope of the present disclosure include program products including machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures, and which can be accessed by a general purpose or special purpose computer or other machine with a processor.

[0053] When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0054] Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure.Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.

[0055] It is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting.

[0056] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another implementation includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another implementation. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0057] “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0058] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal implementation. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0059] Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can beperformed it is understood that each of these additional steps can be performed with any specific implementation or combination of implementations of the disclosed methods.

Claims

WHAT IS CLAIMED IS:

1. A method of generating parameters for ultra-high dose rate (UHDR) radiotherapy (RT), the method comprising: obtaining desired dose and dose rate values for an UHDR RT procedure; obtaining a cone size value for a UHDR electron linear accelerator for the UHDR RT procedure; generate operating parameters for the UHDR electron linear accelerator based on the desired dose and dose rate values and the cone size value; and displaying the operating parameters in a user interface.

2. The method of claim 1, wherein the operating parameters comprise a number of pulses, a dose per pulse (DPP), a pulse width (PW), pulse repetition frequency (PRF), source to surface distance (SSD), and an airgap value.

3. The method of claim 2, wherein varying the airgap value affects beam flatness and field size.

4. The method of claim 2, further comprising assigning a cumulative error to the dose.

5. The method of claim 4, wherein the cumulative error is 6%.

6. The method of claim 2, wherein the PRF is one of 10, 20, 30, 45, and 60 Hz.

7. The method of claim 2, wherein the PW is one of 1, 1.6, 2, 3, and 4 microseconds.

8. The method of claim 2, wherein the dose is determined by the following relationship:D Gy) = N * DPP (60 Hz, 4 gs) * PWF * g (cone, SSD) wherein D is a total dose, A is a number of pulses, DPP is a dose per pulse measured at 60 Hz PRF and 4 ps PW setting for a cone being used at SSD = 18.3 cm, PWF is a pulse width factor to account for relative differences in DPP between pulse width settings, and g is the airgap.

9. The method of claim 15, wherein dose rate is determined using the following relationship:

10. The method of claim 1, further comprising controlling the UHDR electron linear accelerator according to the operating parameters.

11. The method of claim 10, further comprising: monitoring the operating parameters by extracting signals from an accelerator; and recording the pulse waveforms with an oscilloscope.

12. The method of claim 10, further comprising using Alternating Current Current Transformers (ACCTs) in a head of the UHDR electron linear accelerator.

13. The method of claim 10, further comprising configuring the UHDR electron linear accelerator using a collimator made from a polyoxymethylene material.

14. The method of claim 10, wherein the collimator has a diameter of between 2.5 cm and 6 cm.

15. The method of claim 13, wherein the UHDR electron linear accelerator is configured with a source to surface distance (SSD) of 18.3 cm by direct mounting of the collimator on an exit window of a gantry.

16. The method of claim 13, wherein the UHDR electron linear accelerator is configured with a source to surface distance (SSD) of 35 cm by using an applicator.

17. A method of operating an ultra-high dose rate (UHDR) radiotherapy (RT) device, the method comprising: receiving a desired dose and dose rate values for a UHDR RT procedure;receiving a cone size value for a UHDR electron linear accelerator for the UHDR RT procedure; receiving operating parameters for the UHDR electron linear accelerator based on the desired dose and dose rate values and the cone size value; and controlling the UHDR electron linear accelerator according to the operating parameters.

18. The method of claim 17, further comprising: monitoring the operating parameters by extracting signals from an accelerator; and recording the pulse waveforms with an oscilloscope.

19. The method of claim 17, further comprising configuring the UHDR electron linear accelerator using a collimator made from a polyoxymethylene material.

20. The method of claim 17, wherein the UHDR electron linear accelerator is configured with a source to surface distance (SSD) of 18.3 cm by direct mounting of the collimator on an exit window of a gantry.

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