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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Initial Biological Damage from Space Radiation: Implications for Development of Biological Countermeasures

Astronauts are exposed to high-energy nuclear particles originating from the galactic cosmic rays, high-energy protons trapped in the Earth's magnetic field or solar particle events, and secondary radiation produced by nuclear reactions. Important differences between conventional radiation including X-rays or gamma-rays, and high-energy nuclei occur at the level of initial damage to DNA and other potential biological target molecules, and to tissues. Such differences include a large fraction of the initial damage from high charge and energy (HZE) nuclear particles manifested as irreparable lesions including small- and large-scale DNA deletions. Also, low dose-rate exposures in space result in a heterogeneous population of damaged cells distinct from energetic photon irradiation of tissue. We present an overview of the initial biological damage and dose and dose-rate effects produced by ionizing radiation using track structure and nuclear reaction models. Implications of the differences in cellular and tissue damage between conventional radiation and space radiation for the development of biological countermeasures are discussed.

Cucinotta, Francis A.↗
DOE OSTI2016

Initial Report of a Prospective Dosimetric and Clinical Feasibility Trial Demonstrates the Potential of Protons to Increase the Therapeutic Ratio in Breast Cancer Compared With Photons

Purpose: To compare dosimetric endpoints between proton therapy (PT) and conventional radiation and determine the feasibility of PT for regional nodal irradiation (RNI) in women with breast cancer. Methods and Materials: From 2012 to 2014, 18 women (stage IIA-IIIB) requiring RNI prospectively enrolled on a pilot study. Median age was 51.8 years (range, 42-73 years). The cohort included breast-conserving therapy (BCT) and mastectomy patients and right- and left-sided cancers. Treatment targets and organs at risk were delineated on computed tomography scans, and PT and conventional plans were developed. Toxicity was prospectively recorded using Common Terminology Criteria for Adverse Events version 4.0. A Wilcoxon signed-rank sum test compared the dose-volume parameters. The primary endpoint was a reduction in cardiac V5. Results: Median follow-up was 20 months (range, 2-31 months). For all patients, the PT plan better met the dosimetric goals and was used for treatment. Proton therapy alone was used for 10 patients (9 postmastectomy, 1 after BCT) and combined proton–photon in 8 (6 BCT, 2 postmastectomy with immediate expander reconstruction). Proton therapy improved coverage of level 2 axilla (P=.0005). Adequate coverage of internal mammary nodes was consistently achieved with PT (median D95, 50.3 Gy; range, 46.6-52.1 Gy) but not with conventional radiation therapy (median D95, 48.2 Gy; range, 40.8-55 Gy; P=.0005). Median cardiac V5 was 0.6% with PT and 16.3% with conventional radiation (P<.0001). Median ipsilateral lung V5 and V20 were improved with PT (median V5 35.3% vs 60.5% [P<.0001]; and median V20, 21.6% vs 35.5% [P<.0001]). Grade 3 dermatitis developed in 4 patients (22%), which was the only grade 3 toxicity. No grade 4+ toxicities developed. Conclusion: Proton therapy for RNI after mastectomy or BCT significantly improves cardiac dose, especially for left-sided patients, and lung V5 and V20 in all patients without excessive acute toxicity. Proton therapy simultaneously improves target coverage for the internal mammary nodes and level 2 axilla, which may positively impact long-term survival in breast cancer patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Global Harmonization of Quality Assurance Naming Conventions in Radiation Therapy Clinical Trials

Purpose: To review the various radiation therapy quality assurance (RTQA) procedures used by the Global Clinical Trials RTQA Harmonization Group (GHG) steering committee members and present the harmonized RTQA naming conventions by amalgamating procedures with similar objectives. Methods and Materials: A survey of the GHG steering committee members' RTQA procedures, their goals, and naming conventions was conducted. The RTQA procedures were classified as baseline, preaccrual, and prospective/retrospective data capture and analysis. After all the procedures were accumulated and described, extensive discussions took place to come to harmonized RTQA procedures and names. Results: The RTQA procedures implemented within a trial by the GHG steering committee members vary in quantity, timing, name, and compliance criteria. The procedures of each member are based on perceived chances of noncompliance, so that the quality of radiation therapy planning and treatment does not negatively influence the trial measured outcomes. A comparison of these procedures demonstrated similarities among the goals of the various methods, but the naming given to each differed. After thorough discussions, the GHG steering committee members amalgamated the 27 RTQA procedures to 10 harmonized ones with corresponding names: facility questionnaire, beam output audit, benchmark case, dummy run, complex treatment dosimetry check, virtual phantom, individual case review, review of patients' treatment records, and protocol compliance and dosimetry site visit. Conclusions: Harmonized RTQA harmonized naming conventions, which can be used in all future clinical trials involving radiation therapy, have been established. Harmonized procedures will facilitate future intergroup trial collaboration and help to ensure comparable RTQA between international trials, which enables meta-analyses and reduces RTQA workload for intergroup studies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

A New Light Weight Structural Material for Nuclear Structures

Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0mCi 60 Co, 1.8mCi 137 Cs, 13.5mCi 241 Am, and 5.0mCi 133 Ba were used for gamma-ray attenuation analysis. The evaluations of neutron transmission measurements were conducted at the Neutron Powder Diffractometer beam facility at North Carolina State University. The experimental results were verified theoretically through XCOM and Monte Carlo Z-particle Transport Code (MCNP). A mechanical investigation was performed by means of quasi-static compressive testing. Thermal characterizations were carried out through effective thermal conductivity and thermal expansion analyses in terms of high temperature guarded-comparative-longitudinal heat flow technique and thermomechanical analyzer (TMA), respectively. The experimental results were compared with analytical results obtained from, respectively, Brailsford and Major’s model and modified Turner’s model for verification. Flame test was performed in accordance with United States Nuclear Regulatory Commission (USNRC) standard. CMF sample and a 304L stainless steel control sample were subjected to a fully engulfing fire with an average flame temperature of 800°C for a period of 30 minutes. Finite Element Analysis was conducted to secure the credibility of the experimental results. This research indicates the potential of utilizing the light-weight close-cell CMFs and open-cell Al foam with fillers as shielding material replacing current heavy structures with additional advantage of high-energy absorption and excellent thermal characteristics.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Stereology techniques in radiation biology

Clinicians involved in conventional radiation therapy are very concerned about the dose-response relationships of normal tissues. Before proceeding to new clinical protocols, radiation biologists involved with conformal proton therapy believe it is necessary to quantify the dose response and tolerance of the organs and tissues that will be irradiated. An important focus is on the vasculature. This presentation reviews the methodology and format of using confocal microscopy and stereological methods to quantify tissue parameters, cell number, tissue volume and surface area, and vessel length using the microvasculature as a model tissue. Stereological methods and their concepts are illustrated using an ongoing study of the dose response of the microvessels in proton-irradiated hemibrain. Methods for estimating the volume of the brain and the brain cortex, the total number of endothelial cells in cortical microvessels, the length of cortical microvessels, and the total surface area of cortical microvessel walls are presented step by step in a way understandable for readers with little mathematical background. It is shown that stereological techniques, based on a sound theoretical basis, are powerful and reliable and have been used successfully.

Non-NASA Center↗
DOE OSTI2015

Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

Serial femtosecond crystallography (SFX) using X-ray Free-Electron Lasers (XFELs) allows for room temperature protein structure determination without evidence of conventional radiation damage. In this method, a liquid suspension of protein microcrystals can be delivered to the X-ray beam in vacuum as a micro-jet, which replenishes the crystals at a rate that exceeds the current XFEL pulse repetition rate. Gas dynamic virtual nozzles produce the required micrometer-sized streams by the focusing action of a coaxial sheath gas and have been shown to be effective for SFX experiments. Here, we describe the design and characterization of such nozzles assembled from ceramic micro-injection molded outer gas-focusing capillaries. Trends of the emitted jet diameter and jet length as a function of supplied liquid and gas flow rates are measured by a fast imaging system. The observed trends are explained by derived relationships considering choked gas flow and liquid flow conservation. Finally, the performance of these nozzles in a SFX experiment is presented, including an analysis of the observed background.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Hypofractionated Radiation Therapy for Breast Ductal Carcinoma In Situ

Purpose: Conventional radiation therapy (RT) administered in 25 fractions after breast-conserving surgery (BCS) is the standard treatment for ductal carcinoma in situ (DCIS) of the breast. Although accelerated hypofractionated regimens in 16 fractions have been shown to be equivalent to conventional RT for invasive breast cancer, few studies have reported results of using hypofractionated RT in DCIS. Methods and Materials: In this multicenter collaborative effort, we retrospectively reviewed the records of all women with DCIS at 3 institutions treated with BCS followed by hypofractionated whole-breast RT (WBRT) delivered in 16 fractions. Results: Between 2003 and 2010, 440 patients with DCIS underwent BCS followed by hypofractionated WBRT in 16 fractions for a total dose of 42.5 Gy (2.66 Gy per fraction). Boost RT to the surgical bed was given to 125 patients (28%) at a median dose of 10 Gy in 4 fractions (2.5 Gy per fraction). After a median follow-up time of 4.4 years, 14 patients had an ipsilateral local relapse, resulting in a local recurrence-free survival of 97% at 5 years. Positive surgical margins, high nuclear grade, age less than 50 years, and a premenopausal status were all statistically associated with an increased occurrence of local recurrence. Tumor hormone receptor status, use of adjuvant hormonal therapy, and administration of additional boost RT did not have an impact on local control in our cohort. On multivariate analysis, positive margins, premenopausal status, and nuclear grade 3 tumors had a statistically significant worse local control rate. Conclusions: Hypofractionated RT using 42.5 Gy in 16 fractions provides excellent local control for patients with DCIS undergoing BCS.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Prospective Phase 2 Study of Radiation Therapy Dose and Volume De-escalation for Elective Neck Treatment of Oropharyngeal and Laryngeal Cancer

The required elective nodal dose and volumes for head and neck intensity modulated radiation therapy have largely been extrapolated from conventional radiation therapy fields. In this prospective, dual-center, phase 2 study, we investigated the efficacy and tolerability of reduced elective nodal volume and dose in oropharyngeal and laryngeal squamous cell carcinoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1984

Liquid droplet radiator performance studies

By making use of droplets rather than solid surfaces to radiate waste heat in space, the liquid-droplet radiator (LDR) achieves a radiating area/mass much larger than that of conventional radiators which use fins or heat pipes. The light-weight potential of the LDR is shown to be limited primarily by the radiative properties of the droplets. The requirement that the LDR heat-transfer fluid have a very low vapor pressure limits the choice of fluids to relatively few several liquid metals and a silicone fluid are the only suitable candidates so far identified. An experimental determination of the emittance of submillimeter droplets of the silicon fluid indicates that an LDR using this fluid at temperatures of 275-335 K would be about 10 times lighter than the lightest solid-surface radiators. Although several liquid metals appear to offer excellent performance in LDR applications at temperatures between 200 and 975 K, experimental determination of liquid-metal emissivities is needed for a conclusive assessment.

Mattick, A. T.↗
DOE OSTI2021

Establishment of Microbeam Radiation Therapy at a Small-Animal Irradiator

Microbeam radiation therapy is a preclinical concept in radiation oncology. It spares normal tissue more effectively than conventional radiation therapy at equal tumor control. The radiation field consists of peak regions with doses of several hundred gray, whereas doses between the peaks (valleys) are below the tissue tolerance level. Widths and distances of the beams are in the submillimeter range for microbeam radiation therapy. A similar alternative concept with beam widths and distances in the millimeter range is presented by minibeam radiation therapy. Although both methods were developed at large synchrotron facilities, compact alternative sources have been proposed recently.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

WE-AB-BRB-12: Nanoscintillator Fiber-Optic Detector System for Microbeam Radiation Therapy Dosimetry

Purpose: Microbeam Radiation Therapy (MRT) is an experimental radiation therapy that has demonstrated a higher therapeutic ratio than conventional radiation therapy in animal studies. There are several roadblocks in translating the promising treatment technology to clinical application, one of which is the lack of a real-time, high-resolution dosimeter. Current clinical radiation detectors have poor spatial resolution and, as such, are unsuitable for measuring microbeams with submillimeter-scale widths. Although GafChromic film has high spatial resolution, it lacks the real-time dosimetry capability necessary for MRT preclinical research and potential clinical use. In this work we have demonstrated the feasibility of using a nanoscintillator fiber-optic detector (nanoFOD) system for real-time MRT dosimetry. Methods: A microplanar beam array is generated using a x-ray research irradiator and a custom-made, microbeam-forming collimator. The newest generation nanoFOD has an effective size of 70 µm in the measurement direction and was calibrated against a kV ion chamber (RadCal Accu-Pro) in open field geometry. We have written a computer script that performs automatic data collection with immediate background subtraction. A computer-controlled detector positioning stage is used to precisely measure the microbeam peak dose and beam profile by translating the stage during data collection. We test the new generation nanoFOD system, with increased active scintillation volume, against the previous generation system. Both raw and processed data are time-stamped and recorded to enable future post-processing. Results: The real-time microbeam dosimetry system worked as expected. The new generation dosimeter has approximately double the active volume compared to the previous generation resulting in over 900% increase in signal. The active volume of the dosimeter still provided the spatial resolution that meets the Nyquist criterion for our microbeam widths. Conclusion: We have demonstrated that real-time dosimetry of MRT microbeams is feasible using a nanoscintillator fiber-optic detector with integrated positioning system.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1987

Coordinated ultraviolet and radio observations of selected nearby stars

All of the US2 shifts assigned were successfully completed with simultaneous International Ultraviolet Explorer (IUE) and the Very Large Array (VLA) observations of the proposed target stars. The target stars included dwarf M flare stars and RS CVn stars. The combined ultraviolet (IUE) and microwave (VLA) observations have provided important new insights to the radiation mechanisms at these two widely-separated regions of the electromagnetic spectrum. The VLA results included the discovery of narrow-band microwave radiation and rapid time variations in the microwave radiation of dwarf M flare stars. The results indicate that conventional radiation mechanisms cannot explain the microwave emission from these stars. In general, ultraviolet variations and bursts occur when no similar variations are detected at microwave wavelengths and vice versa. Although these is some overlap, the variations in these two spectral regions are usually uncorrelated, suggesting that there is little interaction between the activity centers at the two associated atmospheric levels.

Lang, Kenneth R.↗
DOE OSTI2017

Safety and Efficacy of Stereotactic Ablative Radiation Therapy for Renal Cell Carcinoma Extracranial Metastases

Purpose: Renal cell carcinoma is refractory to conventional radiation therapy but responds to higher doses per fraction. However, the dosimetric data and clinical factors affecting local control (LC) are largely unknown. We aimed to evaluate the safety and efficacy of stereotactic ablative radiation therapy (SAbR) for extracranial renal cell carcinoma metastases. Methods and Materials: We reviewed 175 metastatic lesions from 84 patients treated with SAbR between 2005 and 2015. LC and toxicity after SAbR were assessed with Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 and Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Predictors of local failure were analyzed with χ{sup 2}, Kaplan-Meier, and log-rank tests. Results: In most cases (74%), SAbR was delivered with total doses of 40 to 60 Gy, 30 to 54 Gy, and 20 to 40 Gy in 5 fractions, 3 fractions, and a single fraction, respectively. The median biologically effective dose (BED) using the universal survival model was 134.5 Gy. The 1-year LC rate after SAbR was 91.2% (95% confidence interval, 84.9%-95.0%; median follow-up, 16.7 months). Local failures were associated with prior radiation therapy (hazard ratio [HR], 10.49; P<.0001), palliative-intent radiation therapy (HR, 4.63; P=.0189), spinal location (HR, 5.36; P=.0041), previous systemic therapy status (0-1 vs >1; HR, 3.52; P=.0217), and BED <115 Gy (HR, 3.45; P=.0254). Dose received by 99% of the target volume was the strongest dosimetric predictor for LC. Upon multivariate analysis, dose received by 99% of the target volume greater than BED of 98.7 Gy and systemic therapy status remained significant (HR, 0.12 and 3.64, with P=.0014 and P=.0472, respectively). Acute and late grade 3 toxicities attributed to SAbR were observed in 3 patients (1.7%) and 5 patients (2.9%), respectively. Conclusions: SAbR demonstrated excellent LC of metastatic renal cell carcinoma with a favorable safety profile when an adequate dose and coverage were applied. Multimodality treatment with surgery should be considered for reirradiation or vertebral metastasis. A higher radiation dose may be required in patients who received previous systemic therapies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Impact of Pretreatment Combined {sup 18}F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging on Radiation Therapy Treatment Decisions in Locally Advanced Breast Cancer

Purpose: To assess the diagnostic performance of pretreatment {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography ({sup 18}F-FDG PET/CT) and its impact on radiation therapy treatment decisions in patients with locally advanced breast cancer (LABC). Methods and Materials: Patients with LABC with Eastern Cooperative Oncology Group performance status <2 and no contraindication to neoadjuvant chemotherapy, surgery, and adjuvant radiation therapy were enrolled on a prospective trial. All patients had pretreatment conventional imaging (CI) performed, including bilateral breast mammography and ultrasound, bone scan, and CT chest, abdomen, and pelvis scans performed. Informed consent was obtained before enrolment. Pretreatment whole-body {sup 18}F-FDG PET/CT scans were performed on all patients, and results were compared with CI findings. Results: A total of 154 patients with LABC with no clinical or radiologic evidence of distant metastases on CI were enrolled. Median age was 49 years (range, 26-70 years). Imaging with PET/CT detected distant metastatic disease and/or locoregional disease not visualized on CI in 32 patients (20.8%). Distant metastatic disease was detected in 17 patients (11.0%): 6 had bony metastases, 5 had intrathoracic metastases (pulmonary/mediastinal), 2 had distant nodal metastases, 2 had liver metastases, 1 had pulmonary and bony metastases, and 1 had mediastinal and distant nodal metastases. Of the remaining 139 patients, nodal disease outside conventional radiation therapy fields was detected on PET/CT in 15 patients (10.8%), with involvement of ipsilateral internal mammary nodes in 13 and ipsilateral level 5 cervical nodes in 2. Conclusions: Imaging with PET/CT provides superior diagnostic and staging information in patients with LABC compared with CI, which has significant therapeutic implications with respect to radiation therapy management. Imaging with PET/CT should be considered in all patients undergoing primary staging for LABC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2005

Flexible Metal-Fabric Radiators

Flexible metal-fabric radiators have been considered as alternative means of dissipating excess heat from spacecraft and space suits. The radiators also may be useful in such special terrestrial applications as rejecting heat from space-suit-like protective suits worn in hot work environments. In addition to flexibility and consequent ease of deployment and installation on objects of varying sizes and shapes, the main advantages of these radiators over conventional rigid radiators are that they weigh less and occupy less volume for a given amount of cooling capacity. A radiator of this type includes conventional stainless-steel tubes carrying a coolant fluid. The main radiating component consists of a fabric of interwoven aluminum-foil strips bonded to the tubes by use of a proprietary process. The strip/tube bonds are strong and highly thermally conductive. Coolant is fed to and from the tubes via flexible stainless-steel manifolds designed to accommodate flexing of, and minimize bending forces on, the fabric. The manifolds are sized to minimize pressure drops and distribute the flow of coolant evenly to all the tubes. The tubes and manifolds are configured in two independent flow loops for operational flexibility and protective redundancy.

Cross, Cynthia↗
NASA NTRS2003

Fundamental space radiobiology

The unique feature of the space radiation environment is the dominance of high-energy charged particles (HZE or high LET radiation) emitted by the Sun and galactic sources, or trapped in the Van Allen radiation belts. These charged particles present a significant hazard to space flight crews, and accelerator-based experiments are underway to quantify the health risks due to unavoidable radiation exposure. There are three principal properties of charged particles that distinguish them from conventional radiation, i.e. gamma rays and x-rays. First, they have a defined range in matter rather than an exponential absorption profile. Second, they undergo nuclear reactions to produce secondary particles. Third, and most important, they deposit their energy along well-defined linear paths or tracks rather than diffuse fields. The structured energy deposition pattern interacts on multiple scales with the biological structures of DNA, cells and tissues to produce correlated patterns of damage that evade repair systems. Traditional concepts of dose and its associated normalization parameter, RBE (relative biological effectiveness), break down under experimental scrutiny, and probabilistic models of risk based on the number of particle traversals per cell may be more appropriate. Unique patterns of DNA damage, gene expression, mobilization of repair proteins, activation of cytokines and remodeling of cellular microenvironment are observed following exposure to high LET radiation. At low levels of exposure the communication of bioactive substances from irradiated to unirradiated "bystander" cells can amplify the damage and cause a significant deviation from linearity in dose vs. response relations. Under some circumstances, there is even a multigenerational delay in the expression of radiation-induced genetic damage (genomic instability) which is not strictly dose dependent. These issues and the experimental evidence derived from ground based experiments at particle accelerators are presented along with speculation about how modified inertial conditions might perturb homeostatic responses to radiation to further complicate risk assessment for space flight.

NASA Discipline Radiation Health↗
DOE OSTI2017

Hadron Beam Therapy

Discoveries and technological advances spurred by the demands of nuclear and particle physics research find applications in many disciplines, including providing benefit to society through the treatment and diagnosis of disease. As an example, proton radiation therapy is a precise form of radiation treatment for cancer. Due to the characteristic Bragg peak associated with ion energy deposition, proton therapy provides the radiation oncologist an improved method of treatment localization within a patient, as compared with conventional radiation therapy using X-rays. This can be accomplished only in concert with concurrent advances in tumor identification and localization, patient motion and positioning, treatment planning and evaluation, and a host of supporting technologies. An overview of hadron, in particular proton, therapy will be presented, with some emphasis on landmark and recent technological developments

Keppel, Cynthia↗