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Effect of dosimeter type for commissioning small photon beams on calculated dose distribution in stereotactic radiosurgery

Purpose: To assess the impact of the detector used to commission small photon beams on the calculated dose distribution in stereotactic radiosurgery (SRS). Methods: In this study, six types of detectors were used to characterize small photon beams: three diodes [a silicon stereotactic field diode SFD, a silicon diode SRS, and a silicon diode E], an ionization chamber CC01, and two types of radiochromic film models EBT and EBT2. These detectors were used to characterize circular collimated beams that were generated by a Novalis linear accelerator. This study was conducted in two parts. First, the following dosimetric data, which are of particular interest in SRS, were compared for the different detectors: the total scatter factor (TSF), the tissue phantom ratios (TPRs), and the off-axis ratios (OARs). Second, the commissioned data sets were incorporated into the treatment planning system (TPS) to compare the calculated dose distributions and the dose volume histograms (DVHs) that were obtained using the different detectors. Results: The TSFs data measured by all of the detectors were in good agreement with each other within the respective statistical uncertainties: two exceptions, where the data were systematically below those obtained for the other detectors, were the CC01 results for all of the circular collimators and the EBT2 film results for circular collimators with diameters below 10.0 mm. The OAR results obtained for all of the detectors were in excellent agreement for all of the circular collimators. This observation was supported by the gamma-index test. The largest difference in the TPR data was found for the 4.0 mm circular collimator, followed by the 10.0 and 20.0 mm circular collimators. The results for the calculated dose distributions showed that all of the detectors passed the gamma-index test at 100% for the 3 mm/3% criteria. The aforementioned observation was true regardless of the size of the calculation grid for all of the circular collimators. Finally, the dose volume histogram results were independent of the size of the calculation grid used. Conclusions: The results of this study showed that all of the studied detectors produced similar commissioned data sets for the TPS dose calculations. However, this result only validated the dose distribution calculation in the TPS and could not be used to assess the dose delivery to the target in which the TFS data were used to calculate the monitor units (the TFS data were not used in the TPS dose distribution calculation). Therefore, this study could not be used to determine the most accurate detector commissioning data set; however, all of the detectors exhibited superior performance for the relative dosimetry of small photon beams.

07 ISOTOPE AND RADIATION SOURCES↗

Development of a golden beam data set for the commissioning of a proton double-scattering system in a pencil-beam dose calculation algorithm

Purpose: The purpose of this investigation is to determine if a single set of beam data, described by a minimal set of equations and fitting variables, can be used to commission different installations of a proton double-scattering system in a commercial pencil-beam dose calculation algorithm. Methods: The beam model parameters required to commission the pencil-beam dose calculation algorithm (virtual and effective SAD, effective source size, and pristine-peak energy spread) are determined for a commercial double-scattering system. These parameters are measured in a first room and parameterized as function of proton energy and nozzle settings by fitting four analytical equations to the measured data. The combination of these equations and fitting values constitutes the golden beam data (GBD). To determine the variation in dose delivery between installations, the same dosimetric properties are measured in two additional rooms at the same facility, as well as in a single room at another facility. The difference between the room-specific measurements and the GBD is evaluated against tolerances that guarantee the 3D dose distribution in each of the rooms matches the GBD-based dose distribution within clinically reasonable limits. The pencil-beam treatment-planning algorithm is commissioned with the GBD. The three-dimensional dose distribution in water is evaluated in the four treatment rooms and compared to the treatment-planning calculated dose distribution. Results: The virtual and effective SAD measurements fall between 226 and 257 cm. The effective source size varies between 2.4 and 6.2 cm for the large-field options, and 1.0 and 2.0 cm for the small-field options. The pristine-peak energy spread decreases from 1.05% at the lowest range to 0.6% at the highest. The virtual SAD as well as the effective source size can be accurately described by a linear relationship as function of the inverse of the residual energy. An additional linear correction term as function of RM-step thickness is required for accurate parameterization of the effective SAD. The GBD energy spread is given by a linear function of the exponential of the beam energy. Except for a few outliers, the measured parameters match the GBD within the specified tolerances in all of the four rooms investigated. For a SOBP field with a range of 15 g/cm{sup 2} and an air gap of 25 cm, the maximum difference in the 80%–20% lateral penumbra between the GBD-commissioned treatment-planning system and measurements in any of the four rooms is 0.5 mm. Conclusions: The beam model parameters of the double-scattering system can be parameterized with a limited set of equations and parameters. This GBD closely matches the measured dosimetric properties in four different rooms.

43 PARTICLE ACCELERATORS↗

WE-F-201-00: Practical Guidelines for Commissioning Advanced Brachytherapy Dose Calculation Algorithms

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of the clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.

60 APPLIED LIFE SCIENCES↗

WE-F-201-02: Review TG-186 and WGMBDCA Guidelines, Commission Process, and Dosimetry Benchmarks

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of the clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.

60 APPLIED LIFE SCIENCES↗

SU-F-J-20: Commissioning and Acceptance Testing of the C-Rad CatalystHD Surface Imaging System

Introduction: With the increasing use of surface-based, nonionizing image-guided radiotherapy (IGRT) systems, a comprehensive set of clinical acceptance and commissioning procedures are needed to ensure correct functionality and proper clinical integration. Although TG-147 provides a specific set of parameters, measurement methodologies have yet to be described. The aim of this study was to provide a comprehensive overview of the commissioning and acceptance analysis performed for the C-Rad CatalystHD imaging system. Methods and Materials: Methodology for the commissioning and acceptance of the C-Rad CatalystHD imaging system was developed using commercially available clinical equipment. Following TG-147 guidelines, the following tests were performed: integration of peripheral equipment, system drift, static spatial reproducibility and localization accuracy, static end-to-end analysis, static rotational accuracy, dynamic spatial accuracy, dynamic temporal accuracy, dynamic radiation delivery and a comprehensive end-to-end analysis. Results: The field of view (FOV) of the CatalystHD was 105×109×83 cm3 in the lateral, longitudinal and vertical directions. For thermal equilibrium and system drift, a thermal drift of 1.0mm was noted. A 45 min warmup time is recommended if the system has been shut off an extended period of time (>24 hours) before the QA procedure to eliminate any thermal drift. Spatial reproducibility was found to be 0.05±0.03 mm using a rigid phantom. For the static localization accuracy, system agreement with couch shifts was within 0.1±0.1 mm and positioning agreement with kV-CBCT was 0.16±0.10 mm. For static rotational accuracy, system agreement with a high precision rotational stage (0.01 deg precision) was within 0.10±0.07 deg. Dynamic spatial and temporal localization accuracy was found to be within 0.2±0.1 mm. Conclusion: A comprehensive commissioning and acceptance study was performed using commercially available phantoms and in-house methodologies to provide a performance evaluation of the CatalystHD imaging system.

60 APPLIED LIFE SCIENCES↗

SU-F-J-37: Commissioning a Six Degree of Freedom Couch

Purpose: The proper operation of a six degree of freedom couch (6DOFC) to position a patient for treatment requires that a number systems on the treatment unit work together correctly. Commissioning a 6DOFC requires not only the commissioning of each separate system but also commissioning the interactions between the systems. Methods: To commission a 6DOFC, we tested the resolvers that readout the linear and angular positions; the orthogonality of the axes of the laser positioning system, the imaging system, the gantry and the couch as well as their relationship to each other. An automated Winston-Lutz test was used verify the coincidence of the origins of the laser system, imaging system and treatment unit. The IsoCal phantom was used to verify the consistency of axes orientations between systems. The operation of the couch and imaging system was verified under simulated load conditions and an end to end test was performed to verify correct operation of the system. Results: The tests on the couch resolvers, orthogonality and coincidence of the axes of each system were successfully completed and showed excellent agreement. The automated Winston-Lutz test showed that the maximum displacement of the center of the radiation field with respect to the isocenter was <0.6 mm (radius) at isocenter. The analysis of the IsoCal phantom showed that the maximum variation of the radiation field with respect to known locations in the phantom was ∼0.9 mm for all the BBs in the phantom. Load tests showed maximum errors of 1 mm. Conclusion: We tested all system associated with the 6DOFC and found the uncertainty due to imaging was <.9mm and the uncertainty due to loading ∼1 mm, resulting in a total error of ∼1.4 mm.

60 APPLIED LIFE SCIENCES↗

SU-F-J-179: Commissioning Dosimetric Data of a New 2.5 Megavoltage Imaging Beam from a TrueBeam Linear

Purpose: Recently a new 2.5 megavoltage imaging beam has become available in a TrueBeam linear accelerator for image guidance. There is limited information available related to the beam characteristics. Commissioning dosimetric data of the new imaging is necessary for configuration of the beam in a treatment planning system in order to calculate imaging doses to patients resulting from this new imaging beam. The purpose of this study is to provide measured commissioning data recommended for a beam configuration in a treatment planning system. Methods: A recently installed TrueBeam linear accelerator is equipped with a new low energy photon beam with a nominal energy of 2.5 MV which provides better image quality in addition to other therapeutic megavoltage beams. Dosimetric characteristics of the 2.5 MV are measured for commissioning. An ionization chamber was used to measure dosimetric data including depth-dose curves and dose profiles at different depths for field sizes ranging from 5×5 cm{sup 2} to 40×40 cm{sup 2}. Results: Although the new 2.5 MV beam is a flattening-filter-free (FFF) beam, its dose profiles are much flatter compared to a 6 MV FFF beam. The dose decrease at 20 cm away from the central axis is less than 30% for a 40×40 cm{sup 2} field. This moderately lower dose at off-axis distances benefits the imaging quality. The values of percentage depth-dose (PDD) curves are 53% and 63% for 10×10 cm{sup 2} and 40×40 cm{sup 2} fields respectively. The measured beam output is 0.85 cGy/MU for a reference field size at depth 5 cm obtained according to the AAPM TG-51 protocol. Conclusion: This systematically measured commissioning data is useful for configuring the new imaging beam in a treatment planning system for patient imaging dose calculations resulting from the application of this 2.5 MV beam which is commonly set as a default in imaging procedures.

60 APPLIED LIFE SCIENCES↗

SU-F-T-344: Commissioning Constant Dose Rate VMAT in the Raystation Treatment Planning System for a Varian Clinac IX

Purpose: To demonstrate the commissioning of constant dose rate volumetric modulated arc therapy (VMAT) in the Raystation treatment planning system for a Varian Clinac iX with Exact couch. Methods: Constant dose rate (CDR) VMAT is an option in the Raystation treatment planning system, enabling VMAT delivery on Varian linacs without a RapidArc upgrade. Raystation 4.7 was used to commission CDR-VMAT for a Varian Clinac iX. Raystation arc model parameters were selected to match machine deliverability characteristics. A Varian Exact couch model was added to Raystation 4.7 and commissioned for use in VMAT optimization. CDR-VMAT commissioning checks were performed on the linac, including patient-specific QA measurements for 10 test patients using both the ArcCHECK from Sun Nuclear Corporation and COMPASS from IBA Dosimetry. Multi-criteria optimization (MCO) in Raystation was used for CDR-VMAT planning. Results: Raystation 4.7 generated clinically acceptable and deliverable CDR-VMAT plans for the Varian Clinac. VMAT plans were optimized including a model of the Exact couch with both rails in the out positions. CDR-VMAT plans generated with MCO in Raystation were dosimetrically comparable to Raystation MCO-generated IMRT plans. Patient-specific QA measurements with the ArcCHECK on the couch showed good agreement with the treatment planning system prediction. Patient-specific, structure-specific, multi-statistical parameter 3D QA measurements with gantry-mounted COMPASS also showed good agreement. Conclusion: Constant dose rate VMAT was successfully modeled in Raystation 4.7 for a Varian Clinac iX, and Raystation’s multicriteria optimization generated constant dose rate VMAT plans which were deliverable and dosimetrically comparable to IMRT plans.

60 APPLIED LIFE SCIENCES↗

SU-F-T-495: Method for Simultaneous Commissioning of Multiple Truebeam (TB) Linacs: Small Field Data and the Choice of Dosimetric Lead Gap (DLG)

Purpose: Many times a set of multiple Varian-Truebeam (TB) linacs are acquired by an institution. Since “beam matching” is an important requirement for many facilities, we developed a strategy to perform a “simultaneous” commissioning between multiple linacs.Methods and Materials: We first commissioned the required photon beam data for eclipse on the 1st TB for all the energy modalities with a beam scanning system, while integrated measurements for output factors, of all field sizes (from 1×1 to 40×40cm{sup 2}) were conducted on the 2nd TB. Care was exercised during small field dosimetry so the appropriate detectors were used with data taken between two detectors be “linked” to a larger field size (4×4cm{sup 2}) with the “daisy-chaining” technique via: OF=[M-PTW(fs)×(M-PTW(4×4))-1]×[MA12s(4×4)×(M-A12S(10×10))−1]. For all energy modalities, data that span the entire range of field size, was repeated on the next TB linac, for verification. The primarily energy-dependent dosimetric leaf gap (DLG) which was measured separately on each TB. The modeled data was validated with special measurements conducted on both linacs during commissioning. Results: Our data agreed with the “TB representative beam data” to within 0.5% for all energy modalities and field sizes ≥3×3cm2. Sample depth-doses and cross-profiles of a 3×3cm2 between the linacs agreeing to within 1% between linacs. The measured DLGs were quite different with a uniform difference of 1.3% between the two linacs. The measured DLG values are independent of the average dose rate and medium used for the measurements. Conclusion: A comprehensive method of commissioning identical Varian-TB linacs, outlining the critical issues, especially small field dosimetry and DLG. The dosimetric effect of different DLG values, when it comes to, dynamic delivery and data comparisons will be presented. The dependence of DLG value on the measurement medium (in-air vs. water) or dose rate used will also be discussed. This work was supported by CAMC Cancer Center and Alliance Oncology.

61 RADIATION PROTECTION AND DOSIMETRY↗

Considerations for Resilience Guidelines for Clean Energy Plans: For the Oregon Public Utility Commission and Oregon Electricity Stakeholders

This document summarizes relevant approaches, research, models, and national examples for state utility regulators tasked with developing utility guidelines for risk-based resiliency planning. In 2021, the Oregon Legislature enacted a 100 percent clean electricity by 2040 standard that requires the Oregon Public Utility Commission (PUC) to oversee utility planning for aggressive clean energy deployment through Clean Energy Plans (House Bill 2021, Sec. 4). In addition to meeting emissions reductions targets, Clean Energy Plans must also: "Include a risk-based examination of resiliency opportunities that includes costs, consequences, outcomes, and benefits based on reasonable and prudent industry resiliency standards and guidelines established by the Public Utility Commission." This report will support the Oregon Public Utility Commission in developing resilience guidelines. Other state public utility commissions may also benefit from this research.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Commissioning Status of the Linac for the Facility for Rare Isotope Beams

The Facility for Rare Isotope Beams will be completed in late 2021. Here, we report here on the current efforts to commission the first stages of the 200-MeV/u superconducting, continuous wave heavy-ion linac. The statuses of the cryogenic plant and its distribution system, the accelerator cryomodule commissioning and operations, the ion source and front end transport development, the radio-frequency quadrupole commissioning, and then beam dynamics development to support high-power operation are reviewed. Plans for commissioning the remainder of the linac systems are presented.

43 PARTICLE ACCELERATORS↗

Commissioning of a GeoMelt Vitrification Plant at the Central Laboratory on the Sellafield Site - 17561

The National Nuclear Laboratory (NNL) and Kurion Veolia (Kurion) have installed a GeoMelt{sup R} In-Container Vitrification (ICV){sup R} radioactive waste treatment system in the Central Laboratory Active Rig Hall at Sellafield. This installation was completed in 2016. GeoMelt incorporates a range of patented and proprietary vitrification processing technologies that are configured in a variety of ways depending on the project and the waste. GeoMelt transforms hazardous chemical and radioactive wastes into an inert vitreous monolith. Hazardous organics are destroyed by pyrolysis and heavy metals and radionuclides are immobilized within the glass matrix where they are not preferentially leached into the environment. GeoMelt IVC produces a durable wasteform for a large variety of input wastes. The batch nature of the process which involves single-use refractory offers a wide range of process benefits over traditional vitrification technologies including: - a wide range of waste chemistries allowing high waste loadings; - compatibility with heterogeneous wastes including wastes with high metal content; - a technological simple solution without stirrers, bubblers, etc.; - No refractory corrosion concerns or melter drain failure scenarios; - Flexibility in glass chemistry and melter/disposal container configuration allows the wasteform to be specifically tailored to the storage or disposal site requirements. As part of the 2016 system commissioning at NNL's Central Laboratory, three demonstration melts were performed, one funded by Sellafield Ltd. and two by the Nuclear Decommissioning Authority (NDA). The first melt processed inactive soil with an inactive caesium tracer. The second melt processed inactive soil with a Cs-137 tracer. The third melt processed active waste soil from a variety of NDA nuclear licensed sites. The work conducted during commissioning was multi-purpose; it successfully demonstrated the benefits that the GeoMelt technology could bring to the UK NDA estate while performing equipment testing/troubleshooting and operator training. A significant benefit of the GeoMelt ICV technology is volume reduction for wastes which would otherwise experience a volume increase if encapsulated. Another benefit is the ability to treat difficult radioactive waste streams not amenable to encapsulation (e.g., reactive and/or organic wastes) with a very low energy consumption. The purpose of the first commissioning melt, Plant Performance Demonstration (PPD)-1, was to operate the GeoMelt system under typical conditions and to perform a post-melt mass balance of the caesium as a surrogate for Cs-137 in order to access retention of caesium in the final glass product. The melt processed a mixture of inactive soil obtained near the Sellafield site (as analogue for contaminated Sellafield soil), additives, and glass frit. An inactive caesium tracer was added to this melt as Cs{sub 2}CO{sub 3}. The purpose of the second commissioning melt, PPD-2, was to operate the GeoMelt system under typical conditions and to perform a post-melt activity balance using a Cs-137 tracer in order to assess retention of Cs-137 in the final glass product. Materials processed were inactive soil, glass frit, additives, and a radioactive caesium tracer (CsCl). The purpose of the third melt, Experiment-1 (EX-1) was to treat active waste and inactive waste simulant, as a demonstration of simultaneous processing of multiple waste streams. EX-1 consisted of processing active soil, Magnox sludge simulant, inactive soil, additives, and frit. The active soil used for this melt was obtained from the Hunterston A, Bradwell, Capenhurst, and Sellafield nuclear licensed sites. Since most soils are high in silica, the concept for this experiment was to use the active soils to provide glass formers while co-processing Magnox sludge simulant which does not contain glass formers. Beyond demonstration of capability areas of focus of this series of demonstrations included processing efficiency (kWh/kg treated) and caesium retention (%). This paper summarizes operations and results of the three melts. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Commissioning of a 20 K helium refrigeration system for NASA-JSC Chamber-A

A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL's Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (23 metric tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the design, project execution and commissioning results.

Homan, J.↗

Design, development and commissioning of a multi-alkali semiconductor photocathode deposition system for the IUAC Delhi light source photoinjector

A fourth-generation light source, called Delhi Light Source (DLS) based on photocathode-based RF gun has been commissioned at Inter-University Accelerator Centre, New Delhi. Presently, the electron beam is being generated from copper photocathode and the beam is being used for scheduled experiments. Soon, the semiconductor photocathode will be used to produce higher beam current. Here, to develop the semiconductor photocathode, a dedicated photocathode deposition facility was developed in collaboration with Brookhaven national Laboratory (BNL) and has been successfully commissioned and becomes operational at IUAC. This deposition facility is an integrated system with the electron gun and is a unique system as it is capable of producing, preserving (without residual gas poisoning) and in-vacuum transfer of the deposited photocathodes from the deposition chamber up to the RF electron gun. The system is designed to operate under ultra-high vacuum (UHV) and is equipped with load-lock chambers, substrate heating assembly, thickness monitoring via a quartz crystal microbalance (QCM), and an in-situ setup for quantum efficiency (QE) measurements. After testing of all the subsystems and a detailed calibration, the first deposition of a cesium telluride (Cs 2 Te) photocathode was successfully performed on a copper (Cu) substrate. This successful commissioning and initial deposition mark a significant step toward the indigenous photocathode development and lays the groundwork for further research into advanced photo emissive materials at IUAC. This paper will discuss the salient features, installation, commissioning, first semiconductor photocathode deposition and its results.

47 OTHER INSTRUMENTATION↗

Commissioning and operational results of helium refrigeration system at JLab for the 12GeV upgrade

The new 4.5 K refrigerator system at the Jefferson Lab (JLab) Central Helium Liquefier (CHL-2) for the 12 GeV upgrade was commissioned in late spring of 2013, following the commissioning of the new compressor system, and has been supporting 12 GeV LINAC commissioning since that time. Six design modes were tested during commissioning, consisting of a maximum capacity, nominal capacity, maximum liquefaction, maximum refrigeration, maximum fill and a stand-by/reduced load condition. The maximum capacity was designed to support a 238 g/s, 30 K and 1.16 bar cold compressor return flow, a 15 g/s, 4.5 K liquefaction load and a 12.6 kW, 35-55 K shield load. The other modes were selected to ensure proper component sizing and selection to allow the cold box to operate over a wide range of conditions and capacities. The cold box system is comprised of two physically independent cold boxes with interconnecting transfer-lines. The outside (upper) 300-60 K vertical cold box has no turbines and incorporates a liquid nitrogen pre-cooler and 80-K beds. The inside (lower) 60-4.5 K horizontal cold box houses seven turbines that are configured in four expansion stages including one Joule-Thompson expander and a 20-K bed. The helium compression system has five compressors to support three pressure levels in the cold box. This paper will summarize the analysis of the test data obtained over the wide range of operating conditions and capacities which were tested.

Knudsen, Peter N.↗

Commissioning plan for LCLS II 2 K cold box

Commissioning of the LCLS II cryogenic plant has been planned with respect to electrical and mechanical systems checkout, equipment cleanup, cool-down, and individual performance evaluation. This plant consists of warm and cold storage, helium compressors, 4.5 K and 2 K cold boxes, and all auxiliaries typical for helium refrigeration processes. The 2 K cold box, consisting of five cold compressors in series to produce the flow and pressures necessary for 2K operation, will be the last equipment installed and, along with an additional 10,000 L helium dewar, will allow the entire plant to be commissioned as a single entity. The pre-commissioning stages, commissioning plan for 2 K cold box without connecting to the LCLS II LINAC, additional test equipment needed to simulate the loads, all process studies and associated results are described herein.

36 MATERIALS SCIENCE↗

SU-F-P-34: Commission of Enhanced Dynamic Wedge of Varian Truebeam Linac System with Feature Study

Purpose: To evaluate an Enhanced Dynamic Wedge (EDW) as part of machine commission process with feature study. Methods: The EDW system in this study was from a Truebeam, which is the Linear accelerator manufactured by Varian Medical Systems. The EDW feature vectors includes selected elements. These elements were dosimetric output spots check, field size, wedge angles, dose rate, collimator orientation, and different energy settings. Point dose measurement was done by a PTW farmer chamber, and profiles were measured by Gafchromic EBT2 films positing at different depths of the Solidwater based on the study elements. The output spot measurements were done with PTW farmer chamber with Solidwater setting for all orientation and wedge angles in the EDW system. The profiles comparisons were done by IMRT measurement function in RIT software at version 6.3. And the films were scanned by Vidar scanner. Dosimetry calculation were done by using the same Solidwater scanned by GE LightSpeed CT in Eclipse Treatment Planning System (TPS). Then measurements were compared to simulation results in TPS. Results: The energy average percentage difference between chamber measurement and TPS was 0.16% with standard deviation (SD) at 0.93%. For selected features, the average percentage difference between film measurement and computation was 0.93% with SD at 1.55% in horizontal profiles, and 1.18% with SD at 0.98% at vertical profiles. The average gamma difference for film measurement and TPS computing results was at 0.924 with SD at 0.314. Conclusion: A feature vector was developed to describe the commission of EDW, and developing a complete set of features for sufficiency of commission of a LINAC function could provide optimal commission instance with acceptable confident level of clinical application of the machine. Given the institution specific vector pattern and big data process, it could provide wide range clinical outcome comparison information in application of EDW.

60 APPLIED LIFE SCIENCES↗

Retro-Commissioning Sensor Suitcase

This software package is the Graphic User Interface (GUI) software component for the Sensor Suitcase Retro-Commissioning project, which is a sensor and analysis system to support monitoring-based retro-commissioning of small commercial buildings, performed by non-experts. Small commercial buildings typically do not have the budgets or business economics to allow investing in energy efficiency enhancements the building retro-commissioning provides. In addition, they do not have in-house staff with expertise in building systems who can perform building retro-commissioning or identify energy efficiency improvement opportunities. The solution to this problem is to develop a turn-key hardware/software solution (the RCx Sensor Suitcase) that can be used by non-experts to automatically generate low and no-cost energy efficiency rec commendations that will improve building operating costs, occupant comfort and building energy performance. This is a joint project between Lawrence Berkeley National Laboratory, leading the development of the software and analysis elements, and Pacific Northwest National Laboratory (PNNL), leading the development of the hardware and sensor elements with an associated table-based configuration support tool. The project is funded by the U.S. Department of Energy. This software package was developed as a proof-of-concept prototype for the sensor suitcase software component. The software component was developed with a Microsoft Excel spreadsheet which reads the sensor data and calls a MATLAB DLL to analyze the sensor data.

Lin, Guanjing↗