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NASA NTRS1981

Geodesy by radio interferometry - Intercontinental distance determinations with subdecimeter precision

Analysis of very-long-baseline interferometer (VLBI) observations yielded estimates of the distances between three radio telescopes in the United States and one in Sweden, with formal standard errors of a few centimeters: Westford, Massachusetts-Onsala, Sweden: 5,599,714.66 + or - 0.03 m; Green Bank, West Virginia-Onsala, Sweden: 6,319,317.75 + or - 0.03 m; and Owens Valley, California-Onsala, Sweden: 7,914,131.19 + or - 0.04 m, where the earth-fixed reference points are defined in each case with respect to the axes of the telescopes. The actual standard errors are difficult to estimate reliably but are probably not greater than twice the formal errors.

Herring, T. A.↗

DOE OSTI2018

The effect of temperature, storage time and collection method on biomethane potential of source separated household food waste

Highlights: • Experiments to mimic storage of OFMSW performed in laboratory scale at 6 and 22 °C. • A recipe representative for OFMSW from households in Sweden was designed. • Clear signs of degradation for OFMSW stored at 22 °C with respect to time. • Higher loss of VS and H{sub 2}O for OFMSW in paper bags compared to plastic bags at 22 °C. - Abstract: The aim of this study was to mimic real conditions for storage and transport and to evaluate how much of the biomethane potential is lost before the organic fraction of municipal solid waste (OFMSW) from households in Sweden reaches the biogas plant. The laboratory biomethane potential (BMP) experiments was carried out with respect to the storage time, collection method (paper or plastic bag) and storage temperature (22 °C and 6 °C) in order to evaluate the effect of these factors on the biomethane potential. A recipe representative for OFMSW from households in Sweden was designed with the help of literature and modification of recipes from technical reports and scientific literature. Laboratory experiments showed that the difference in the BMP of OFMSW stored in plastic- compared to paper bags were obvious at 22 °C with a lower biomethane potential for paper bags, but there was no difference at 6 °C. Provided that the loss of organic matter during pre-treatment is equivalent for both paper and plastic bags it is possible to get more biomethane from OFMSW collected in plastic bags during the warmest part of the year, since they have a more preservative effect on OFMSW than paper bags. This could be explained by the plastic bags being denser than paper and therefore maintain the volatile organic compounds inside the bag and promote a pre-hydrolysis of the material rather than aerobic degradation.

09 BIOMASS FUELS↗

DOE OSTI2019

Different Approaches for Clearance of Metals - a Comparison - 19079

Large quantities of contaminated and potentially contaminated metals are generated during the lifetime of nuclear installations, especially when they are dismantled and demolished. In many countries, clearance for recycling is considered Best Practice for the management of metals which are contaminated or potentially contaminated. In some countries, such as Sweden, it has become a legal requirement to recycle metals and other materials when it is safe to do so and the cost is reasonable. Therefore, multiple management routes are available with the aim of establishing a graded approach. These include general (unconditional) clearance, conditional (specific) clearance of surface contaminated metals, conditional clearance of metal ingots after treatment in a licensed facility and in some cases, recycling inside the nuclear sector. Kemakta Konsult AB recently derived rounded clearance limits for the conditional clearance of scrap metal for re-melting from the decommissioning of Swedish nuclear sites, on behalf of the Swedish Radiation Safety Authority (SSM). The calculations used the RP89 exposure scenarios, but the parameters were adjusted to reflect normal practice in the Swedish scrap metal and recycling industries. The study found that, for most of the 39 radionuclides judged to be relevant, the rounded clearance levels were the same as or higher than those in RP 89. However, longer transport times in Sweden compared to the ones used for RP 89 resulted in lower rounded clearance levels for three gamma-emitting radionuclides, including Co-60, the most important radionuclide in terms of dose exposure. Cyclife Sweden AB has, through more than 40 years of operation of the metal treatment facility at the Studsvik industrial site, significant experience of the practical implementation of clearing metal ingots as well as metallic strap, in total about 50,000 tonnes. A previous study confirms very low radiological impact to the receivers of the ingots and to the general public under the current procedures and conditions for clearance. The production of steel ingots for recycling in the Cyclife plant involves pre-treatment (segmentation and decontamination) followed by melting. Certain nuclides, like Cs-137 and alpha nuclides, are transferred to the secondary waste (slag and filter dust) in the melting process. The non-separated nuclides are homogenized in the ingot. The radionuclides that are present in the ingots are expected to remain in the metal during re-melting at metal works. The general approach of [1] together with specific information for typical ingots has been used to further verify the radiological implications of applying conditional clearance of ingots. This paper provides a background, present the studies performed, give an overview of the findings and the overall result including a comparison between different approaches. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Transport and Treatment of Chapelcross Gas Ducts for Clearance and Recycling - 19662

In the summer of 2018, Cyclife, the EDF group's specialist radioactive waste management and decommissioning company, transported sixteen gas ducts and associated equipment from the shutdown Chapelcross nuclear power plant to treatment facilities in the UK and Sweden. The client requested a full removal, treatment and disposal service for approximately 820 te of low level metallic waste comprising Upper Gas Duct Assemblies (including bellows), Upper Gas Duct elbows, Filter Pots and Convoluted pipework. The complex scope involved heavy lifting, transport by road and sea, processing and recycling on a large scale, thereby necessitating involvement of a wide range of suppliers at different tiers all managed by Cyclife. The purpose of the entire project was to safely handle and treat all of the components for clearance and recycling into the public domain for the manufacture of new steel products. Most of the treatment took place in Cyclife's nuclear licensed metal treatment facility in Sweden. Cyclife has a long and unique experience of arranging safe transport of large contaminated components on road and sea. The metal treatment facility in Sweden can, without special arrangements, receive components up to 30 meters long with a weight of up to 400 tonnes for decontamination, size reduction and melting. The actual treatment of the components consisted of the following steps: a) Separation of a gas duct from the gantry, b) size reduction, radiological verification measurements and clearance of the gantry, c) stepwise segmentation of the gas duct and elbow including removal of asbestos, d) decontamination, e) melting, f) radiological assessment and clearance of the metal ingots, g) management of the secondary waste for return to UK. The result of the project, upon completed treatment of all the material, demonstrates a high recycling rate of the material. 5-10% of the original mass of material will have to disposed as radioactive waste. This number include all residues, untreatable material (asbestos, mineral wool, filters etc.) and two melt batches with a too high activity content for clearance. The paper takes the reader through the entire project from the initial planning to the clearance of the metal and the return of the secondary waste to UK for disposal. It will also present and discuss pros and cons for alternative management approaches in several perspectives. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2014

Swedish Government Representatives Visit Nevada National Security Site and Los Alamos National Laboratory for Nuclear Nonproliferation Workshop

In October 2013, Los Alamos National Laboratory, with sponsorship and support from the NNSA Office of Nonproliferation and International Security, Office of Nuclear Controls (NA-242), hosted representatives from various agencies of the Swedish Government for a Nuclear Nonproliferation Workshop (NNPW). The purpose of the visit was to further promote the strong and mutually beneficial working relationship between the U.S. and Sweden on nuclear nonproliferation and related nuclear export control and safeguards subjects. Sweden is an important “like-minded” partner in the NSG and in other multilateral activities, such as implementation of special nuclear trade sanctions against Iran and North Korea, which work to combat the global nuclear proliferation problem. Sweden has been especially active in policy and technical initiatives in the NSG that serve to make the NSG’s export control lists better and more effective in combating nuclear proliferation activities.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2017

Fiscal Year (FY) 2017 Activities for the Spent Fuel Nondestructive Assay Project

The main focus of research in the NA-241 spent fuel nondestructive assay (NDA) project in FY17 has been completing the fabrication and testing of two prototype instruments for upcoming spent fuel measurements at the Clab interim storage facility in Sweden. One is a passive instrument: Differential Die-away Self Interrogation-Passive Neutron Albedo Reactivity (DDSI), and one is an active instrument: Differential Die-Away-Californium Interrogation with Prompt Neutron (DDA). DDSI was fabricated and tested with fresh fuel at Los Alamos National Laboratory in FY15 and FY16, then shipped to Sweden at the beginning of FY17. Research was performed in FY17 to simplify results from the data acquisition system, which is complex because signals from 56 different 3He detectors must be processed using list mode data. The DDA instrument was fabricated at the end of FY16. New high count rate electronics better suited for a spent fuel environment (i.e., KM-200 preamplifiers) were built specifically for this instrument in FY17, and new Tygon tubing to house electrical cables was purchased and installed. Fresh fuel tests using the DDA instrument with numerous configurations of fuel rods containing depleted uranium (DU), low enriched uranium (LEU), and LEU with burnable poisons (Gd) were successfully performed and compared to simulations.1 Additionally, members of the spent fuel NDA project team travelled to Sweden for a “spent fuel characterization and decay heat” workshop involving simulations of spent fuel and analysis of uncertainties in decay heat calculations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2023

Abstract for CRADA among NETL, Mälardalen University, University College Cork (acting through its Tyndall National Institute), and Micro Electricity Generation Association

GeoCoHorT aims to accelerate the transition to 4 th generation district heating and cooling (4GDHC) in Europe and globally, by assessing, optimizing, and demonstrating the integration of shallow geothermal heat extraction with other renewable sources and smart buildings. The target geo-source is ground water from River Shannon (Limerick, Ireland), which will provide both an efficiency and noise-reduction benefit to the micro-district and a method of combatting climate-change-warming of the Shannon Estuary. The heat from this low-temperature source will be recycled and supplied to a smart district located in Limerick, Ireland, through heat pumps powered by renewable electricity and by means of a suitable DH network design. The mandate is to find solutions that work for entire communities in a fair and sustainable manner, with the involvement of the communities themselves to highlight their needs. The project brings together four partners from Ireland, Sweden, and the U.S.A. with strong multi-disciplinary competencies. The Tyndall Institute at University of Cork (UCC) and Mälardalen University (MDU) will design and optimize the 4GDH micro-district system, and the Micro Electricity Generation Association (MEGA) will work with the community to build a sense of ownership of the Climate Challenge and ensure close community involvement. The National Energy Technology Laboratory of the U.S. Department of Energy (NETL) will design the prospective geo-fluid loop to optimize heat-extraction effectiveness with ecological safety and assess the environmental benefits of the proposed solutions. Industrial advisors (Eskilstuna Strängnäs Energi och Miljö (ESEM) and Mimer in Sweden, and Smart MPOWER in Ireland) will steer the technology development to meet the needs of public utilities and consumers. Current infrastructure in the smart district in Limerick (demonstration site of an EU Lighthouse project) will be exploited and modified with support of MEGA, UCC, and MPOWER to integrate micro-DH from low-temperature heat sources, such as the river heat, and to allow increasing penetration of prosumers in the grid. Additional case studies will be developed with the help of industrial advisors to extend the results to other regions (e.g., Sweden and USA) and provide valuable insights for the development of 4GDH worldwide.

15 GEOTHERMAL ENERGY↗

NASA NTRS1984

International comparative study of systems for the government advancement of research and development

The reorganization, structure and instruments of government advancement of research in three countries was compared: France, Sweden and the USA. In France the powers are centralized; in Sweden and the USA, decentralized. Assistance to projects is provided with grants and contracts in all three countries. France and Sweden also give loans with conditional waiving of reimbursement in case of failure. In all three countries indirect assistance is provided only with small tax breaks.

Ripke, M.↗

DOE OSTI2014

Portal dosimetry for VMAT using integrated images obtained during treatment

Purpose: Portal dosimetry provides an accurate and convenient means of verifying dose delivered to the patient. A simple method for carrying out portal dosimetry for volumetric modulated arc therapy (VMAT) is described, together with phantom measurements demonstrating the validity of the approach. Methods: Portal images were predicted by projecting dose in the isocentric plane through to the portal image plane, with exponential attenuation and convolution with a double-Gaussian scatter function. Appropriate parameters for the projection were selected by fitting the calculation model to portal images measured on an iViewGT portal imager (Elekta AB, Stockholm, Sweden) for a variety of phantom thicknesses and field sizes. This model was then used to predict the portal image resulting from each control point of a VMAT arc. Finally, all these control point images were summed to predict the overall integrated portal image for the whole arc. The calculated and measured integrated portal images were compared for three lung and three esophagus plans delivered to a thorax phantom, and three prostate plans delivered to a homogeneous phantom, using a gamma index for 3% and 3 mm. A 0.6 cm{sup 3} ionization chamber was used to verify the planned isocentric dose. The sensitivity of this method to errors in monitor units, field shaping, gantry angle, and phantom position was also evaluated by means of computer simulations. Results: The calculation model for portal dose prediction was able to accurately compute the portal images due to simple square fields delivered to solid water phantoms. The integrated images of VMAT treatments delivered to phantoms were also correctly predicted by the method. The proportion of the images with a gamma index of less than unity was 93.7% ± 3.0% (1SD) and the difference between isocenter dose calculated by the planning system and measured by the ionization chamber was 0.8% ± 1.0%. The method was highly sensitive to errors in monitor units and field shape, but less sensitive to errors in gantry angle or phantom position. Conclusions: This method of predicting integrated portal images provides a convenient means of verifying dose delivered using VMAT, with minimal image acquisition and data processing requirements.

61 RADIATION PROTECTION AND DOSIMETRY↗

DOE OSTI2016

Engaging local industry in the development of basic research infrastructure and instrumentation – The case of HIE-ISOLDE and ESS Scandinavia

Two world-class research facilities, the European Spallation Source, ESS, and the light-source facility MAX-IV, are being built in southern Sweden. They will primarily, when completed, be used for research in the fields of material sciences, life sciences, medicine and pharmacology. Their construction and the operation and maintenance of them for many years will create new business opportunities for companies in Europe in general and in Sweden, Denmark and Norway in particular in many different sectors. A project, CATE, Cluster for Accelerator Technology, was set up with the aim to strengthen the skills of companies in the Öresund-Kattegat-Skagerrak region in Scandinavia in the field of accelerator technology such that they will become competitive and be able to take advantage of the potential of these two research facilities. CATE was strategically important and has helped to create partnerships between companies and new business opportunities in the region.

43 PARTICLE ACCELERATORS↗

DOE OSTI2014

Benchmarking of a treatment planning system for spot scanning proton therapy: Comparison and analysis of robustness to setup errors of photon IMRT and proton SFUD treatment plans of base of skull meningioma

Purpose: Base of skull meningioma can be treated with both intensity modulated radiation therapy (IMRT) and spot scanned proton therapy (PT). One of the main benefits of PT is better sparing of organs at risk, but due to the physical and dosimetric characteristics of protons, spot scanned PT can be more sensitive to the uncertainties encountered in the treatment process compared with photon treatment. Therefore, robustness analysis should be part of a comprehensive comparison between these two treatment methods in order to quantify and understand the sensitivity of the treatment techniques to uncertainties. The aim of this work was to benchmark a spot scanning treatment planning system for planning of base of skull meningioma and to compare the created plans and analyze their robustness to setup errors against the IMRT technique. Methods: Plans were produced for three base of skull meningioma cases: IMRT planned with a commercial TPS [Monaco (Elekta AB, Sweden)]; single field uniform dose (SFUD) spot scanning PT produced with an in-house TPS (PSI-plan); and SFUD spot scanning PT plan created with a commercial TPS [XiO (Elekta AB, Sweden)]. A tool for evaluating robustness to random setup errors was created and, for each plan, both a dosimetric evaluation and a robustness analysis to setup errors were performed. Results: It was possible to create clinically acceptable treatment plans for spot scanning proton therapy of meningioma with a commercially available TPS. However, since each treatment planning system uses different methods, this comparison showed different dosimetric results as well as different sensitivities to setup uncertainties. The results confirmed the necessity of an analysis tool for assessing plan robustness to provide a fair comparison of photon and proton plans. Conclusions: Robustness analysis is a critical part of plan evaluation when comparing IMRT plans with spot scanned proton therapy plans.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2015

Dosimetric characterization of two radium sources for retrospective dosimetry studies

Purpose: During the first part of the 20th century, {sup 226}Ra was the most used radionuclide for brachytherapy. Retrospective accurate dosimetry, coupled with patient follow up, is important for advancing knowledge on long-term radiation effects. The purpose of this work was to dosimetrically characterize two {sup 226}Ra sources, commonly used in Sweden during the first half of the 20th century, for retrospective dose–effect studies. Methods: An 8 mg {sup 226}Ra tube and a 10 mg {sup 226}Ra needle, used at Radiumhemmet (Karolinska University Hospital, Stockholm, Sweden), from 1925 to the 1960s, were modeled in two independent Monte Carlo (MC) radiation transport codes: GEANT4 and MCNP5. Absorbed dose and collision kerma around the two sources were obtained, from which the TG-43 parameters were derived for the secular equilibrium state. Furthermore, results from this dosimetric formalism were compared with results from a MC simulation with a superficial mould constituted by five needles inside a glass casing, placed over a water phantom, trying to mimic a typical clinical setup. Calculated absorbed doses using the TG-43 formalism were also compared with previously reported measurements and calculations based on the Sievert integral. Finally, the dose rate at large distances from a {sup 226}Ra point-like-source placed in the center of 1 m radius water sphere was calculated with GEANT4. Results: TG-43 parameters [including g{sub L}(r), F(r, θ), Λ, and s{sub K}] have been uploaded in spreadsheets as additional material, and the fitting parameters of a mathematical curve that provides the dose rate between 10 and 60 cm from the source have been provided. Results from TG-43 formalism are consistent within the treatment volume with those of a MC simulation of a typical clinical scenario. Comparisons with reported measurements made with thermoluminescent dosimeters show differences up to 13% along the transverse axis of the radium needle. It has been estimated that the uncertainty associated to the absorbed dose within the treatment volume is 10%–15%, whereas uncertainty of absorbed dose to distant organs is roughly 20%–25%. Conclusions: The results provided here facilitate retrospective dosimetry studies of {sup 226}Ra using modern treatment planning systems, which may be used to improve knowledge on long term radiation effects. It is surely important for the epidemiologic studies to be aware of the estimated uncertainty provided here before extracting their conclusions.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2020

Enhanced Sustainability in Treatment of Contaminated Metals for Clearance and Recycling - 20290

Cyclife Sweden AB has, for more than 30 years, provided metal treatment services to the domestic and international nuclear industry with the aim of creating value through metal clearance and recycling. These operations are to a large extent based on the concept that the materials, after pre-treatment, including decontamination, will be melted for clearance. During the melting process, some nuclides separate from the metal while the remaining radioactivity becomes fully homogenized in the metal bath and the resulting ingots, along with the samples taken before casting At a time when activities to fight Climate Challenge are in focus, any savings in energy consumption, in addition to the positive environmental effect of recycling metals back to industry, is more than welcome. If the clearance of certain metallic items can be achieved safely, without using melting, it is the environmentally preferred option provided it carries a reasonable cost. It is even better if an object can go through a decontamination and clearance process prior to re-use inside or outside the nuclear sector. Cyclife Sweden is currently investing in a direct clearance process, to be operated in parallel with the melting process. This new process is expected to be fully operational in the late summer of 2020 and includes pre-treatment, decontamination and heavily shielded clearance measurement installations. The treatment will also allow clearance measurements of larger objects without the need for segmentation, along with allowing objects composed of different materials, like electric motors can be accepted for treatment. This paper gives an overview of the circular economy aspects in a nuclear back-end context, the Cyclife approach to further implement a circular economy approach in the processes, Material Acceptance Criteria for treatment, the facility set-up for the new process and how the melting route and the direct route can be combined in an efficient industrial scale process. To put the new capabilities into perspective, the two different treatment and clearance approaches, i.e. direct clearance and melting, are to be compared. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2024

Fragmentation in Collisions of Snow with Graupel/Hail: New Formulation from Field Observations

Abstract Secondary ice production (SIP) has been attributed to the generation of most ice particles observed in precipitating clouds with cloud tops warmer than −36°C, from various aircraft- and ground-based field observations across the globe. One of the known SIP mechanisms is fragmentation during collisions among ice particles. It has been studied with our theoretical formulation, which has been applied in microphysical schemes of atmospheric models in a few studies. These have predicted an extensive impact on cloud glaciation and radiative properties. However, there has been a lack of experimental field studies, especially involving naturally falling snowflakes, to better understand this particular mechanism of SIP. This study reports the first field measurements with modern technology for fragmentation during collisions between naturally falling snowflakes and graupel/hail particles. This was observed with an innovatively designed portable chamber that was deployed outdoors in northern Sweden. Applying the observations from this field-based study, we optimized the existing formulation for predicting numbers of fragments from collisions of snow with graupel/hail. The observations show the average numbers of fragments per collision for dendritic (3–12 mm) and nondendritic (1–3 mm) snow were about 12 and 1, respectively. This represents a boost of predicted fragment numbers relative to our original formulation published in 2017. The updated formulation for breakup in ice–ice collisions can be implemented in the microphysical schemes of atmospheric models.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2017

Calling computers names in Swedish

I very much enjoyed reading Jim Fleming’s article on Carl-Gustaf Rossby and the seminal contributions Rossby made to meteorology. Furthermore, the otherwise excellent article has two errors. Something must have gotten lost in translation to cause Fleming to claim that “Rossby pursued numerical weather prediction in Sweden in an era in which there was no Swedish word for digital computer.” With applied mathematician Germund Dahlquist, Rossby developed a weather model for the Binär Elektronisk Sekvens Kalkylator (BESK; Binary Electronic Sequence Calculator). Designed and built in Sweden, BESK was the world’s fastest computer when it became operational in 1953. From September 1954, BESK weather simulations enabled routine 24-hour national forecasts.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2019

An Automated Vehicle Fuel Economy Benefits Evaluation Framework Using Real-World Travel and Traffic Data

Increasing automation is a consistent development trend in the automobile industry. However, real-world evaluation of the operational and energy consumption differences between automated vehicles and comparable manually driven vehicles has been limited. This study helps fill the information gap by comparing the operation and fuel economy of vehicles in adaptive cruise control (ACC) and non-ACC modes based on large-scale field test data collected by Volvo Car Corporation (Volvo Cars) from vehicles traveling on the designated 'Drive Me' project road network in Gothenburg, Sweden. The test vehicles' travel data are classified by driving mode (ACC vs. non-ACC) and driving conditions, which refer to traffic speed and road grade in this study. The results from the data logging fleet are used to estimate the aggregate fuel consumption differences at the Drive Me road-network level for vehicles traveling in ACC vs. non-ACC mode based on appropriately weighting the total amount of travel that took place on the network under different driving conditions. At the ACC penetration levels observed in the field test data, vehicles tended to drive more smoothly in ACC mode than in non-ACC mode. The corresponding travel-weighted fuel consumption rate for vehicles in ACC mode was about 5%-7% lower than for vehicles in non-ACC mode when traveling at similar conditions. Sensitivity analyses impart confidence in this result, and in the future, the established evaluation framework could be used to objectively quantify potential on-road fuel consumption impacts from vehicles with even higher levels of automated driving capability.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2018

Pre-Viking Swedish Hillfort Glass: A Prospective Long-Term Alteration Analogue for Vitrified Nuclear Waste

Examining ancient anthropogenic glasses altered in natural environments over hundreds of years can inform and verify models for predicting long-term rates of glass corrosion. Understanding corrosion mechanisms is critical for modeling the performance of nuclear waste glasses that are required to retain radionuclides for >1000 years, and will be disposed in shallow subsurface environments. Two types of ancient Swedish hillfort glasses — one clear, iron-poor glass, and one dark, iron-rich glass — have been characterized to evaluate their use as long-term alteration analogues for vitrified nuclear waste disposed under near-surface conditions. These glasses are of interest to the nuclear waste glass community as they have comparable elemental compositions to glasses under development for disposal of nuclear waste at the Hanford Site, USA. They are also of historical importance to Sweden; thus, an analysis protocol, focusing on non-destructive to semi-destructive analyses, has been developed to maintain the historical integrity of the samples. X-ray computed tomography, micro X-ray diffraction, micro X-ray fluorescence, and electron microscopy data are presented for both vitreous and mineralogical components of the hillfort samples. The internal microstructure and elemental distribution of the glasses, including the presence of crystalline inclusions, are discussed in the context of ancient glassmaking technology.

Weaver, Jamie L.↗

DOE OSTI2016

TH-AB-201-10: Portal Dosimetry with Elekta IViewDose:Performance of the Simplified Commissioning Approach Versus Full Commissioning

Purpose: Elekta recently developed a solution for in-vivo EPID dosimetry (iViewDose, Elekta AB, Stockholm, Sweden) in conjunction with the Netherlands Cancer Institute (NKI). This uses a simplified commissioning approach via Template Commissioning Models (TCMs), consisting of a subset of linac-independent pre-defined parameters. This work compares the performance of iViewDose using a TCM commissioning approach with that corresponding to full commissioning. Additionally, the dose reconstruction based on the simplified commissioning approach is validated via independent dose measurements. Methods: Measurements were performed at the NKI on a VersaHD™ (Elekta AB, Stockholm, Sweden). Treatment plans were generated with Pinnacle 9.8 (Philips Medical Systems, Eindhoven, The Netherlands). A farmer chamber dose measurement and two EPID images were used to create a linac-specific commissioning model based on a TCM. A complete set of commissioning measurements was collected and a full commissioning model was created.The performance of iViewDose based on the two commissioning approaches was compared via a series of set-to-work tests in a slab phantom. In these tests, iViewDose reconstructs and compares EPID to TPS dose for square fields, IMRT and VMAT plans via global gamma analysis and isocentre dose difference. A clinical VMAT plan was delivered to a homogeneous Octavius 4D phantom (PTW, Freiburg, Germany). Dose was measured with the Octavius 1500 array and VeriSoft software was used for 3D dose reconstruction. EPID images were acquired. TCM-based iViewDose and 3D Octavius dose distributions were compared against the TPS. Results: For both the TCM-based and the full commissioning approaches, the pass rate, mean γ and dose difference were >97%, <0.5 and <2.5%, respectively. Equivalent gamma analysis results were obtained for iViewDose (TCM approach) and Octavius for a VMAT plan. Conclusion: iViewDose produces similar results with the simplified and full commissioning approaches. Good agreement is obtained between iViewDose (simplified approach) and the independent measurement tool. This research is funded by Elekta Limited.

60 APPLIED LIFE SCIENCES↗