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All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Planning large-scale excavation and construction activities within an aerially constrained site for construction of a repository for low and short-lived intermediate level radioactive waste at the Bulgarian national disposal facility - 15372

The Bulgarian State Enterprise for Radioactive Waste Management (SERAW) is planning the construction of a near-surface repository for low and short-lived intermediate level radioactive waste, the National Disposal Facility (NDF), at the Radiana Site adjacent to the Kozloduy Nuclear Power Plant (KNPP). The Site, a rectangular area approximately 1.2 km east-west by 0.4 north-south, is located on a slopping area between the second and sixth loess terraces above the River Danube with elevations ranging from approximately +40 m to elevation +95 m. Construction of the NDF will be divided into three phases separated by approximately 20 years each. The first phase will see the construction of the primary support facilities, referred to as the Auxiliary Buildings and including the Waste Reception and Buffer Storage (WRBS) Building, and the first set of 22 reinforced concrete disposal cells and supporting infrastructure, including a network of subsurface observation galleries, the Infiltration Network Control (ICN) Galleries. Each disposal cell will be 20.15 m long by 17.05 m wide by 9.45 m in height. The disposal cells will be arranged in two parallel rows. Disposal activities will be conducted using overhead cranes installed inside of track mounted mobile roofs. Each row of disposal cells will be serviced by one mobile roof. The mobile roofs will be supported by massive concrete foundations. Construction at the site will present several logistical challenges that will need to be overcome to fully realize the NDF. First in order to begin construction of these facilities nearly 1 million 3 of soil will require excavation and handling. Consistent with requirements to minimize potential environmental impacts identified in the site Environmental Safety Assessment (EIA) excavated soil will, to the extent possible, remain onsite. Approximately three quarters of the soil can be accommodated within the site boundaries. Another challenge results from requirements imposed by the ground conditions. The sub-grade at the site, which consists primarily of loess, will require considerable improvement. To this end a 5 m thick loess-cement cushion will be constructed across much of the site. Specifically, the cushion will be required beneath the disposal cells and the WRBS Building. Construction of the loess-cement cushion in the disposal area will require detailed planning and coordination, particularly as the cushion beneath the disposal cells also contains embedded structures, including the ICN Galleries as well as massive concrete foundation beams required for the two mobile roofs. Construction of these structures will require planned interruptions in the construction of the loess-cement cushion. Specific cement types and strict quality requirements will be required for completion of the loess-cement cushion as well as for completion of the ICN Galleries. The construction planning will need to account for the large volumes of soil to be excavated as well as ensuring sufficient material supplies in terms of both quality as well as quantity. Large quantities of materials including both dry cement for mixing with the loess, and wet concrete for pouring of the mobile roof foundations are accounted for by the plan. However, even after completion of these activities additional challenges are addressed by the plan related to the contemporaneous construction management of the auxiliary buildings and the disposal cells. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Upgrade Your Work Plans for Better Performance - 16103

Most work plans involve at least two basic pieces: a list of things to do and a timeline for doing them. These 'tasks-and-times' plans can be used for managing a project, an organizational change, or the implementation of a strategic objective. But given the high rate of plan failures - often cited as ranging from 35% to over 80% - something must be missing. Three ideas for upgrading work plans have demonstrated higher success rates than the time-and-task method alone. First, maintain a 'GPS Scorecard' of the Goals, Performance metrics, and Schedules for accomplishment. Second, maintain a Performance Circle Register of all key players, and the key deliverables to and from each of them, that will ensure success. Third, implement all three parts of an accountability management system, collectively referred to as 'T3': Tracking, Team assignments, and Talk-times to update status and progress against the plan. Why bother to take the extra steps to strengthen work plans? There are three reasons: (a) Because traveling without a map is risky in times of high change in infrastructure, staffing, and technology; (b) Because 'expectations' do not guarantee delivery as reliably as well-defined agreements; and (c) Because 'accountability' is a management practice, not a personality trait. Together, implementing these three ideas can provide for clarity of purpose, guidance in establishing the productive relationships necessary for success, and a system of supporting accountability for all participants, both on the team and with others inside and outside of the organization. (authors)

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2016

Overview of the U.S. Department of Energy, Office of Nuclear Energy's Nuclear Fuel Storage and Transportation Planning Project

The U.S. Department Energy, Office of Nuclear Energy (DOE-NE) is laying the groundwork for implementing interim storage, including associated transportation, per the Administration's Strategy for the Management and Disposal of Used Nuclear Fuel and High- Level Radioactive Waste, and to develop a foundation for a new nuclear waste management organization. The organization within DOE-NE that is responsible for this planning is the Office of Nuclear Fuels Storage and Transportation (NFST). The technical work to support this planning effort is being conducted by DOE's national laboratories. DOE's overarching goal is to develop options for decision-makers on the design of an integrated waste management system. The goal is to develop an integrated plan to (1) implement interim storage; (2) improve the overall integration of storage as a planned part of the waste management system; (3) prepare for the large-scale transportation of SNF and high-level waste (HLW), with an initial focus on removing SNF from the shutdown reactor sites; and (4) develop the foundational information, resources, and capabilities needed to support future implementation decisions and actions. Near-term objectives are to (1) develop and maintain an integrated plan to accomplish the Administration's Strategy goals, (2) improve integration of storage as a planned part of the waste management system, (including evaluating standardization of dry cask storage systems), (3) develop and evaluate design options for an integrated waste management system, (4) develop and apply systems analyses to provide quantitative estimates of system impacts of utility actions' impacts on the system and inform future decisions, (5) prepare for the large-scale transportation of SNF and HLW, (with an initial focus on removing SNF from the shutdown reactor sites), and (6) establish and maintain a unified, integrated SNF database and analysis system to characterize the input to the waste management system. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Renewable Energy Zone (REZ) Transmission Planning Process: A Guidebook for Practitioners

Achieving clean energy goals may require new investments in transmission, especially if planners anticipate economic growth and increased demand for electricity. The renewable energy zone (REZ) transmission planning process can help policymakers ensure their infrastructure investments achieve national goals in the most economical manner. Policymakers, planners, and system operators around the world have used variations of the REZ process to chart the expansion of their transmission networks and overcome the barriers of traditional transmission planning. This guidebook seeks to help power system planners, key decision makers, and stakeholders understand and use the REZ transmission planning process to integrate transmission expansion planning and renewable energy generation planning.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2018

Task 1 Report - Assessment of Data Availability to Inform Energy Planning Analyses: Energy Alternatives Study for the Lao People's Democratic Republic: Smart Infrastructure for the Mekong Program

In an effort to address concerns such as energy security, reliability, affordability, and other objectives, the Government of the Lao People's Democratic Republic (Lao PDR) is seeking to advance its expertise and experience in energy system analysis and planning to explore energy alternatives. Assessing the potential and alternatives for deploying energy technology options is often an early step - and, in most cases, an ongoing process - in planning for the development of the energy sector as a whole. Reliable and robust data are crucial to conducting these types of planning-related analyses in a transparent manner that builds confidence among power sector stakeholders and encourages investment in future energy project development and infrastructure opportunities. This report represents the first output of the Energy Alternatives Study for the Lao PDR (Energy Alternatives Study), a collaboration between Ministry of Energy and Mines and the United States Agency for International Development (USAID) under the auspices of the Smart Infrastructure for the Mekong (SIM) program. The Energy Alternatives Study includes five tasks that build upon each other to meet the goal of the project. The report summarizes the availability, quality, and accessibility of data that serve as key inputs to energy planning activities for the power sector. The purpose of this data assessment is two-fold: 1. To facilitate the informed use of existing data by highlighting applications for these data as they relate to priority energy planning analyses; and 2. To inform future investments in energy data collection and management by identifying significant data gaps and providing guidance on how to fill these gaps.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Monitoring, Evaluating, and Updating Your Community Solar Action Plan

The Community Solar Action Plan is a living document that guides community solar planning action over time. As conditions change, new information becomes available, or actions progress over the life of the plan, adjustments may be necessary to maintain the plan's relevance. This fact sheet describes some things to consider when implementing, monitoring, evaluating, and updating the Community Solar Action Plan over time.

14 SOLAR ENERGY↗
DOE OSTI2013

Social Impact Management Plans: Innovation in corporate and public policy

Social Impact Assessment (SIA) has traditionally been practiced as a predictive study for the regulatory approval of major projects, however, in recent years the drivers and domain of focus for SIA have shifted. This paper details the emergence of Social Impact Management Plans (SIMPs) and undertakes an analysis of innovations in corporate and public policy that have put in place ongoing processes – assessment, management and monitoring – to better identify the nature and scope of the social impacts that might occur during implementation and to proactively respond to change across the lifecycle of developments. Four leading practice examples are analyzed. The International Finance Corporation (IFC) Performance Standards require the preparation of Environmental and Social Management Plans for all projects financed by the IFC identified as having significant environmental and social risks. Anglo American, a major resources company, has introduced a Socio-Economic Assessment Toolbox, which requires mine sites to undertake regular assessments and link these assessments with their internal management systems, monitoring activities and a Social Management Plan. In South Africa, Social and Labour Plans are submitted with an application for a mining or production right. In Queensland, Australia, Social Impact Management Plans were developed as part of an Environmental Impact Statement, which included assessment of social impacts. Collectively these initiatives, and others, are a practical realization of theoretical conceptions of SIA that include management and monitoring as core components of SIA. The paper concludes with an analysis of the implications for the practice of impact assessment including a summary of key criteria for the design and implementation of effective SIMPs. -- Highlights: • Social impact management plans are effective strategies to manage social issues. • They are developed in partnership with regulatory agencies, investors and community. • SIMPs link assessment to ongoing management and address social and community issues. • SIMPs clarify responsibilities in the management of impacts, opportunities and risks. • SIMPs demonstrate a shift to include management as a core component of SIA practice.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Strategic environmental assessment of energy planning tools. A study of Italian regions and provinces

SEA has been applied in different ways in EU energy and environmental planning instruments, because different member states have interpreted European Directive 2001/42/CE in a variety of ways. Italy, for example, has only recently completed the integration of the directive into its legislation, through a number of decrees which were approved between 2006 and 2010. As a result SEA practice in Italy is very fragmented, particularly with respect to energy planning, and needs to be steered towards homogeneous quality objectives. The aim of this paper is to study the quality of the SEA reports on the energy and environmental planning tools used by Italian regions and provinces. We study nine cases and use the methodology suggested by Fisher (2010) in his review of the quality of SEA. To be more precise, we integrate the views of external evaluators with those of a selection of the personnel directly involved in preparing the plans. Our results show that there are some differences in the quality scores given by the outsiders and insiders, although the two groups identified similar strengths and weaknesses in implementing SEA. - Highlights: • This is a comparative study on SEA report quality within Italian energy planning tools. • In Italy, the level of SEA implementation on energy planning is still poor. • External academic experts and internal officers assessed SEA reports' quality. • Outsiders and insiders unveil a similar judgement. • Most critical remarks concern consultation, monitoring measures, and follow-up.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Cumulative effects in strategic environmental assessment: The influence of plan boundaries

Cumulative effects (CE) assessment is lacking quality in impact assessment (IA) worldwide. It has been argued that the strategic environmental assessment (SEA) provides a suitable IA framework for addressing CE because it is applied to developments with broad boundaries, but few have tested this claim. Through a case study on the Danish mining sector, this article explores how plan boundaries influence the analytical boundaries applied for assessing CE in SEA. The case was studied through document analysis in combination with semi-structured group interviews of the responsible planners, who also serve as SEA practitioners. It was found that CE are to some extent assessed and managed implicitly throughout the planning process. However, this is through a focus on lowering the cumulative stress of mining rather than the cumulative stress on and capacity of the receiving environment. Plan boundaries do influence CE assessment, though all boundaries are not equally influential. The geographical and time boundaries of the Danish mining plans are broad or flexible enough to accommodate a meaningful assessment of CE, but the topical boundary is restrictive. The study indicates that collaboration among planning authorities and legally appointed CE leadership may facilitate better practice on CE assessment in sector-specific SEA contexts. However, most pressing is the need for relating assessment to the receiving environment as opposed to solely the stress of a proposed plan.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

[{sup 18}F]FDG-Positron Emission Tomography Coregistration With Computed Tomography Scans for Radiation Treatment Planning of Lymphoma and Hematologic Malignancies

Purpose: Positron emission-tomography (PET) using 2-[{sup 18}F]fluoro-2-deoxyglucose (FDG-PET) increases sensitivity and specificity of disease detection in lymphoma and thus is standard in lymphoma management. This study examines the effects of coregistering FDG-PET and computed tomography (CT) (PET/CT) scans on treatment planning for lymphoma patients. Methods and Materials: Twenty-nine patients (30 positive PET scans) underwent PET/CT treatment planning from July 2004 to February 2007 and were retrospectively studied. For each patient, gross tumor volume was blindly contoured on the CT-only and PET/CT studies by a radiation oncologist. Treatment plans were generated for both the CT-only and PET/CT planning target volumes (PTVs) for all patients. Normal tissue doses and PTV coverage were evaluated using dose--volume histograms for all sites. Results: Thirty-two treatment sites were evaluated. Twenty-one patients had non-Hodgkin lymphoma, 5 patients had Hodgkin lymphoma, and 3 patients had plasma cell neoplasms. Previously undetected FDG-avid sites were identified in 3 patients during PET/CT simulation, resulting in one additional treatment field. Due to unexpected PET/CT simulation findings, 2 patients did not proceed with radiation treatment. The addition of PET changed the volume of 23 sites (72%). The PTV was increased in 15 sites (47%) by a median of 11% (range, 6-40%) and reduced in 8 sites (25%) by a median of 20% (range, 6%-75%). In six (19%) replanned sites, the CT-based treatment plan would not have adequately covered the PTV defined by PET/CT. Conclusions: Incorporation of FDG-PET into CT-based treatment planning for lymphoma patients resulted in considerable changes in management, volume definition, and normal tissue dosimetry for a significant number of patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Effect of Radiotherapy Planning Complexity on Survival of Elderly Patients With Unresected Localized Lung Cancer

Purpose: To evaluate whether complex radiotherapy (RT) planning was associated with improved outcomes in a cohort of elderly patients with unresected Stage I-II non-small-cell lung cancer (NSCLC). Methods and Materials: Using the Surveillance, Epidemiology, and End Results registry linked to Medicare claims, we identified 1998 patients aged >65 years with histologically confirmed, unresected stage I-II NSCLC. Patients were classified into an intermediate or complex RT planning group using Medicare physician codes. To address potential selection bias, we used propensity score modeling. Survival of patients who received intermediate and complex simulation was compared using Cox regression models adjusting for propensity scores and in a stratified and matched analysis according to propensity scores. Results: Overall, 25% of patients received complex RT planning. Complex RT planning was associated with better overall (hazard ratio 0.84; 95% confidence interval, 0.75-0.95) and lung cancer-specific (hazard ratio 0.81; 95% confidence interval, 0.71-0.93) survival after controlling for propensity scores. Similarly, stratified and matched analyses showed better overall and lung cancer-specific survival of patients treated with complex RT planning. Conclusions: The use of complex RT planning is associated with improved survival among elderly patients with unresected Stage I-II NSCLC. These findings should be validated in prospective randomized controlled trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Feasibility of Proton Beam Therapy for Ocular Melanoma Using a Novel 3D Treatment Planning Technique

Purpose: We evaluated sparing of normal structures using 3-dimensional (3D) treatment planning for proton therapy of ocular melanomas. Methods and Materials: We evaluated 26 consecutive patients with choroidal melanomas on a prospective registry. Ophthalmologic work-up included fundoscopic photographs, fluorescein angiography, ultrasonographic evaluation of tumor dimensions, and magnetic resonance imaging of orbits. Three tantalum clips were placed as fiducial markers to confirm eye position for treatment. Macula, fovea, optic disc, optic nerve, ciliary body, lacrimal gland, lens, and gross tumor volume were contoured on treatment planning compute tomography scans. 3D treatment planning was performed using noncoplanar field arrangements. Patients were typically treated with 3 fields, with at least 95% of planning target volume receiving 50 GyRBE in 5 fractions. Results: Tumor stage was T1a in 10 patients, T2a in 10 patients, T2b in 1 patient, T3a in 2 patients, T3b in 1 patient, and T4a in 2 patients. Acute toxicity was mild. All patients completed treatment as planned. Mean optic nerve dose was 10.1 Gy relative biological effectiveness (RBE). Ciliary body doses were higher for nasal (mean: 11.4 GyRBE) than temporal tumors (5.8 GyRBE). Median follow-up was 31 months (range: 18-40 months). Six patients developed changes which required intraocular bevacizumab or corticosteroid therapy, but only 1 patient developed neovascular glaucoma. Five patients have since died: 1 from metastatic disease and 4 from other causes. Two patients have since required enucleation: 1 due to tumor and 1 due to neovascular glaucoma. Conclusions: 3D treatment planning can be used to obtain appropriate coverage of choroidal melanomas. This technique is feasible with relatively low doses to anterior structures, and appears to have acceptable rates of local control with low risk of enucleation. Further evaluation and follow-up is needed to determine optimal dose-volume relationships for organs at risk to decrease complications rates.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Reoptimization of Intensity Modulated Proton Therapy Plans Based on Linear Energy Transfer

Purpose: We describe a treatment plan optimization method for intensity modulated proton therapy (IMPT) that avoids high values of linear energy transfer (LET) in critical structures located within or near the target volume while limiting degradation of the best possible physical dose distribution. Methods and Materials: To allow fast optimization based on dose and LET, a GPU-based Monte Carlo code was extended to provide dose-averaged LET in addition to dose for all pencil beams. After optimizing an initial IMPT plan based on physical dose, a prioritized optimization scheme is used to modify the LET distribution while constraining the physical dose objectives to values close to the initial plan. The LET optimization step is performed based on objective functions evaluated for the product of LET and physical dose (LET×D). To first approximation, LET×D represents a measure of the additional biological dose that is caused by high LET. Results: The method is effective for treatments where serial critical structures with maximum dose constraints are located within or near the target. We report on 5 patients with intracranial tumors (high-grade meningiomas, base-of-skull chordomas, ependymomas) in whom the target volume overlaps with the brainstem and optic structures. In all cases, high LET×D in critical structures could be avoided while minimally compromising physical dose planning objectives. Conclusion: LET-based reoptimization of IMPT plans represents a pragmatic approach to bridge the gap between purely physical dose-based and relative biological effectiveness (RBE)-based planning. The method makes IMPT treatments safer by mitigating a potentially increased risk of side effects resulting from elevated RBE of proton beams near the end of range.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Online Adaptive Hyperthermia Treatment Planning During Locoregional Heating to Suppress Treatment-Limiting Hot Spots

Background: Adequate tumor temperatures during hyperthermia are essential for good clinical response, but excessive heating of normal tissue should be avoided. This makes locoregional heating using phased array systems technically challenging. Online application of hyperthermia treatment planning could help to improve the heating quality. The aim of this study was to evaluate the clinical benefit of online treatment planning during treatment of pelvic tumors heated with the AMC-8 locoregional hyperthermia system. Methods: For online adaptive hyperthermia treatment planning, a graphical user interface was developed. Electric fields were calculated in a preprocessing step using our in-house–developed finite-difference–based treatment planning system. This allows instant calculation of the temperature distribution for user-selected phase-amplitude settings during treatment and projection onto the patient's computed tomographic scan for online visualization. Online treatment planning was used for 14 treatment sessions in 8 patients to reduce the patients' reports of hot spots while maintaining the same level of tumor heating. The predicted decrease in hot spot temperature should be at least 0.5°C, and the tumor temperature should decrease less than 0.2°C. These predictions were compared with clinical data: patient feedback about the hot spot and temperature measurements in the tumor region. Results: In total, 17 hot spot reports occurred during the 14 sessions, and the alternative settings predicted the hot spot temperature to decrease by at least 0.5°C, which was confirmed by the disappearance of all 17 hot spot reports. At the same time, the average tumor temperature was predicted to change on average −0.01°C (range, −0.19°C to 0.34°C). The measured tumor temperature change was on average only −0.02°C (range, −0.26°C to 0.31°C). In only 2 cases the temperature decrease was slightly larger than 0.2°C, but at most it was 0.26°C. Conclusions: Online application of hyperthermia treatment planning is reliable and very useful to reduce hot spots without affecting tumor temperatures.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Choosing a reliability inspection plan for interval censored data

Reliability test plans are important for producing precise and accurate assessment of reliability characteristics. This paper explores different strategies for choosing between possible inspection plans for interval censored data given a fixed testing timeframe and budget. A new general cost structure is proposed for guiding precise quantification of total cost in inspection test plan. Multiple summaries of reliability are considered and compared as the criteria for choosing the best plans using an easily adapted method. Different cost structures and representative true underlying reliability curves demonstrate how to assess different strategies given the logistical constraints and nature of the problem. Results show several general patterns exist across a wide variety of scenarios. Given the fixed total cost, plans that inspect more units with less frequency based on equally spaced time points are favored due to the ease of implementation and consistent good performance across a large number of case study scenarios. Plans with inspection times chosen based on equally spaced probabilities offer improved reliability estimates for the shape of the distribution, mean lifetime, and failure time for a small fraction of population only for applications with high infant mortality rates. The paper uses a Monte Carlo simulation based approach in addition to the common evaluation based on the asymptotic variance and offers comparison and recommendation for different applications with different objectives. Additionally, the paper outlines a variety of different reliability metrics to use as criteria for optimization, presents a general method for evaluating different alternatives, as well as provides case study results for different common scenarios.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Integrated energy-water-land nexus planning to guide national policy: an example from Uruguay

Despite broad consensus on the benefits of a nexus approach to multi-sector planning, actual implementation in government and other decision-making institutions is still rare. This study presents an approach to conducting integrated energy-water-land (EWL) planning, using Uruguay as an example. This stakeholder-driven study focuses on assessing the EWL nexus implications of actual planned policies aimed at strengthening three of Uruguay's key exports (beef, soy, and rice), which account for more than 40% of total national export revenue. Five scenarios are analyzed in the study: a reference scenario, a climate impacts scenario, and three policy scenarios. The three policy scenarios include measures such as increasing the intensity of beef production while simultaneously decreasing emissions, increasing irrigated soybean production, and improving rice yields. This study supplements previous sector-specific planning efforts in Uruguay by conducting the first stakeholder-driven integrated multi-sector assessment of planned policies in Uruguay using a suite of integrated modeling tools. Key insights from the study are: as compared to a reference scenario, improving beef productivity could lead to cropland expansion (+30%) and significant indirect increases in water requirements (+20%); improving rice yields could lead to increases in total emissions (+3%), which may partially offset emissions reductions from other policies; expanding irrigated soy could have the least EWL impacts amongst the policies studied; and climate-driven changes could have significantly less impact on EWL systems as compared to human actions. The generalizable insights derived from this analysis are readily applicable to other countries facing similar multi-sector planning challenges. In particular, the study's results reinforce the fact that policies often have multi-sector consequences, and thus policies can impact one another's efficacy. Thus, policy design and implementation can benefit from coordination across sectors and decision-making institutions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Purpose: To demonstrate the feasibility of photon energy-modulated radiotherapy during beam-on time. Methods: A cylindrical device made of aluminum was conceptually proposed as an energy modulator. The frame of the device was connected with 20 tubes through which mercury could be injected or drained to adjust the thickness of mercury along the beam axis. In Monte Carlo (MC) simulations, a flattening filter of 6 or 10 MV linac was replaced with the device. The thickness of mercury inside the device varied from 0 to 40 mm at the field sizes of 5 x 5 cm{sup 2} (FS5), 10 x 10 cm{sup 2} (FS10), and 20 x 20 cm{sup 2} (FS20). At least 5 billion histories were followed for each simulation to create phase space files at 100 cm source to surface distance (SSD). In-water beam data were acquired by additional MC simulations using the above phase space files. A treatment planning system (TPS) was commissioned to generate a virtual machine using the MC-generated beam data. Intensity modulated radiation therapy (IMRT) plans for six clinical cases were generated using conventional 6 MV, 6 MV flattening filter free, and energy-modulated photon beams of the virtual machine. Results: As increasing the thickness of mercury, Percentage depth doses (PDD) of modulated 6 and 10 MV after the depth of dose maximum were continuously increased. The amount of PDD increase at the depth of 10 and 20 cm for modulated 6 MV was 4.8% and 5.2% at FS5, 3.9% and 5.0% at FS10 and 3.2%-4.9% at FS20 as increasing the thickness of mercury from 0 to 20 mm. The same for modulated 10 MV was 4.5% and 5.0% at FS5, 3.8% and 4.7% at FS10 and 4.1% and 4.8% at FS20 as increasing the thickness of mercury from 0 to 25 mm. The outputs of modulated 6 MV with 20 mm mercury and of modulated 10 MV with 25 mm mercury were reduced into 30%, and 56% of conventional linac, respectively. The energy-modulated IMRT plans had less integral doses than 6 MV IMRT or 6 MV flattening filter free plans for tumors located in the periphery while maintaining the similar quality of target coverage, homogeneity, and conformity. Conclusions: The MC study for the designed energy modulator demonstrated the feasibility of energy-modulated photon beams available during beam-on time. The planning study showed an advantage of energy-and intensity modulated radiotherapy in terms of integral dose without sacrificing any quality of IMRT plan.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

A Monte Carlo approach to validation of FFF VMAT treatment plans for the TrueBeam linac

Purpose: To commission and benchmark a vendor-supplied (Varian Medical Systems) Monte Carlo phase-space data for the 6 MV flattening filter free (FFF) energy mode on a TrueBeam linear accelerator for the purpose of quality assurance of clinical volumetric modulated arc therapy (VMAT) treatment plans. A method for rendering the phase-space data compatible with BEAMnrc/DOSXYZnrc simulation software package is presented. Methods: Monte Carlo (MC) simulations were performed to benchmark the TrueBeam 6 MV FFF phase space data that have been released by the Varian MC Research team. The simulations to benchmark the phase space data were done in three steps. First, the original phase space which was created on a cylindrical surface was converted into a format that was compatible with BEAMnrc. Second, BEAMnrc was used to create field size specific phase spaces located underneath the jaws. Third, doses were calculated with DOSXYZnrc in a water phantom for fields ranging from 1 Multiplication-Sign 1 to 40 Multiplication-Sign 40 cm{sup 2}. Calculated percent depth doses (PDD), transverse profiles, and output factors were compared with measurements for all the fields simulated. After completing the benchmarking study, three stereotactic body radiotherapy (SBRT) VMAT plans created with the Eclipse treatment planning system (TPS) were calculated with Monte Carlo. Ion chamber and film measurements were also performed on these plans. 3D gamma analysis was used to compare Monte Carlo calculation with TPS calculations and with film measurement. Results: For the benchmarking study, MC calculated and measured values agreed within 1% and 1.5% for PDDs and in-field transverse profiles, respectively, for field sizes >1 Multiplication-Sign 1 cm{sup 2}. Agreements in the 80%-20% penumbra widths were better than 2 mm for all the fields that were compared. With the exception of the 1 Multiplication-Sign 1 cm{sup 2} field, the agreement between measured and calculated output factors was within 1%. It is of note that excellent agreement in output factors for all field sizes including highly asymmetric fields was achieved without accounting for backscatter into the beam monitor chamber. For the SBRT VMAT plans, the agreement between Monte Carlo and ion chamber point dose measurements was within 1%. Excellent agreement between Monte Carlo, treatment planning system and Gafchromic film dose distribution was observed with over 99% of the points in the high dose volume passing the 3%, 3 mm gamma test. Conclusions: The authors have presented a method for making the Varian IAEA compliant 6 MV FFF phase space file of the TrueBeam linac compatible with BEAMnrc/DOSXYZnrc. After benchmarking the modified phase space against measurement, they have demonstrated its potential for use in MC based quality assurance of complex delivery techniques.

60 APPLIED LIFE SCIENCES↗