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At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Phosphorus speciation analysis of fatty-acid-based feedstocks and fast pyrolysis biocrudes via gel permeation chromatography inductively coupled plasma high-resolution mass spectrometry

Renewable feedstocks, such as lignocelulosic fast pyrolysis oils and both vegetable oil and animal fats, are becoming a viable alternative to petroleum for producing high-quality renewable transportation fuels. However, the presence of phosphorus-containing compounds, mainly from phospholipids, in these renewable feedstocks is known to poison and deactivate hydrotreating catalysts during fuel production. In this work, gel permeation chromatography (GPC) combined with inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) was used to analyze feedstocks including unprocessed soybean oil, animal fat, and pyrolysis oils from red oak and milorganite to identify phosphorus species. The results have shown the presence of a wide range of different phosphorous compounds among all the samples analysed in this work. The GPC-ICP-HRMS analyses of a vegetable oil and two animal fats have shown different fingerprints based on the molecular weight of each of the samples, highlighting the structural differences among their corresponding phosphorus-containing compounds. While the presence of low-molecular-weight species, such as phospholipids, was expected, several high-molecular-weight species (MW > 10 000 Da) have been found, suggesting that high-molecular-weight micelles or liposomes might have been formed due to the high concentration of phospholipids in these samples. Results obtained through the hydroxylation of a mix of phospholipids (asolectin) and its posterior GPC-ICP-HRMS agree with this hypothesis. With respect to the lignocellulosic catalytic fast pyrolysis oil samples, the GPC-ICP-HRMS results obtained suggest that either aggregation or polymerization reactions might have occurred during the pyrolysis process, yielding phosphorus-containing compounds with an approximate molecular weight above 91 000 kDa. In addition, an aggregation phenomenom has been observed for those phosphorus species present within the fast pyrolysis oils after being stored for 3 months, especially for those pyrolysis oils contaning pre-processed feedstocks, such as milorganite.

09 BIOMASS FUELS↗
DOE OSTI2013

Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ{sup 18}O and δ{sup 2}H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ{sup 18}O and δ{sup 2}H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Application of cellular automata approach for cloud simulation and rendering

Current techniques for creating clouds in games and other real time applications produce static, homogenous clouds. These clouds, while viable for real time applications, do not exhibit an organic feel that clouds in nature exhibit. These clouds, when viewed over a time period, were able to deform their initial shape and move in a more organic and dynamic way. With cloud shape technology we should be able in the future to extend to create even more cloud shapes in real time with more forces. Clouds are an essential part of any computer model of a landscape or an animation of an outdoor scene. A realistic animation of clouds is also important for creating scenes for flight simulators, movies, games, and other. Our goal was to create a realistic animation of clouds.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Swine acute diarrhea syndrome coronavirus replication in primary human cells reveals potential susceptibility to infection

Zoonotic coronaviruses represent an ongoing threat, yet the myriads of circulating animal viruses complicate the identification of higher-risk isolates that threaten human health. Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a newly discovered, highly pathogenic virus that likely evolved from closely related HKU2 bat coronaviruses, circulating in Rhinolophus spp. bats in China and elsewhere. As coronaviruses cause severe economic losses in the pork industry and swine are key intermediate hosts of human disease outbreaks, we synthetically resurrected a recombinant virus (rSADS-CoV) as well as a derivative encoding tomato red fluorescent protein (tRFP) in place of ORF3. rSADS-CoV replicated efficiently in a variety of continuous animal and primate cell lines, including human liver and rectal carcinoma cell lines. Of concern, rSADS-CoV also replicated efficiently in several different primary human lung cell types, as well as primary human intestinal cells. rSADS-CoV did not use human coronavirus ACE-2, DPP4, or CD13 receptors for docking and entry. Contemporary human donor sera neutralized the group I human coronavirus NL63, but not rSADS-CoV, suggesting limited human group I coronavirus cross protective herd immunity. Importantly, remdesivir, a broad-spectrum nucleoside analog that is effective against other group 1 and 2 coronaviruses, efficiently blocked rSADS-CoV replication in vitro. rSADS-CoV demonstrated little, if any, replicative capacity in either immune-competent or immunodeficient mice, indicating a critical need for improved animal models. Efficient growth in primary human lung and intestinal cells implicate SADS-CoV as a potential higher-risk emerging coronavirus pathogen that could negatively impact the global economy and human health.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Outsourced hearing in an orb-weaving spider that uses its web as an auditory sensor

Hearing is a fundamental sense of many animals, including all mammals, birds, some reptiles, amphibians, fish, and arthropods. The auditory organs of these animals are extremely diverse in anatomy after hundreds of millions of years of evolution, yet all are made up of cellular tissue and are morphologically part of the bodies of animals. Here, we show that hearing in the orb-weaving spider Larinioides sclopetarius is not constrained by the organism’s body but is extended through outsourcing hearing to its extended phenotype, the proteinaceous, self-manufactured orb web. We find that the wispy, wheel-shaped orb web acts as a hyperacute acoustic antenna to capture the sound-induced air particle movements that approach the maximum physical efficiency better than the acoustic responsivity of all previously known eardrums. By sensing the motion of web threads, the spider remotely detects and localizes the source of an incoming airborne acoustic wave, such as those emitted by approaching prey or predators. By outsourcing its acoustic sensors to its web, the spider is released from body size constraints and permits the araneid spider to increase its sound-sensitive surface area enormously, up to 10,000 times greater than the spider itself. The spider also enables the flexibility to functionally adjust and regularly regenerate its external "eardrum" according to its needs. The outsourcing and supersizing of auditory function in spiders provides unique features for studying extended and regenerative sensing and designing novel acoustic flow detectors for precise fluid dynamic measurement and manipulation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Comparative electrophysiological evaluation of hippocampal function following repeated inhalation exposures to JP-8, Jet A, JP-5, and the synthetic Fischer Tropsch fuel

Exposure to fuels continues to be a concern in both military and general populations. The aim of this study was to examine effects of in vivo rat repeated exposures to different types of jet fuel utilizing microelectrode arrays for comparative electrophysiological (EP) measurements in hippocampal slices. Animals were exposed to increasing concentrations of four jet fuels, Jet Propellant (JP)-8, Jet A, JP-5, or synthetic Fischer Tropsch (FT) fuel via whole-body inhalation for 20 d (6 hr/d, 5 d/week for 28 d) and synaptic transmission as well as behavioral performance were assessed. Our behavioral studies indicated no significant changes in behavioral performance in animals exposed to JP-8, Jet A, or JP-5. A significant deviation in learning pattern during the Morris water maze task was observed in rats exposed to the highest concentration of FT (2000 mg/m 3 ). There were also significant differences in the EP profile of hippocampal neurons from animals exposed to JP-8, Jet A, JP-5, or FT compared to control air. However, these differences were not consistent across fuels or dose dependent. As expected, patterns of EP alterations in brain slices from JP-8 and Jet A exposures were more similar compared to those from JP-5 and FT. Further longitudinal investigations are needed to determine if these EP effects are transient or persistent. Such studies may dictate if and how one may use EP measurements to indicate potential susceptibility to neurological impairments, particularly those that result from inhalation exposure to chemicals or mixtures.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

The future of fungi: threats and opportunities

The fungal kingdom represents an extraordinary diversity of organisms with profound impacts across animal, plant, and ecosystem health. Fungi simultaneously support life, by forming beneficial symbioses with plants and producing life-saving medicines, and bring death, by causing devastating diseases in humans, plants, and animals. With climate change, increased antimicrobial resistance, global trade, environmental degradation, and novel viruses altering the impact of fungi on health and disease, developing new approaches is now more crucial than ever to combat the threats posed by fungi and to harness their extraordinary potential for applications in human health, food supply, and environmental remediation. To address this aim, the Canadian Institute for Advanced Research (CIFAR) and the Burroughs Wellcome Fund convened a workshop to unite leading experts on fungal biology from academia and industry to strategize innovative solutions to global challenges and fungal threats. This report provides recommendations to accelerate fungal research and highlights the major research advances and ideas discussed at the meeting pertaining to 5 major topics: (1) Connections between fungi and climate change and ways to avert climate catastrophe; (2) Fungal threats to humans and ways to mitigate them; (3) Fungal threats to agriculture and food security and approaches to ensure a robust global food supply; (4) Fungal threats to animals and approaches to avoid species collapse and extinction; and (5) Opportunities presented by the fungal kingdom, including novel medicines and enzymes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Impact of Blast Overpressure on the Pharmacokinetics of Various Antibiotics in Sprague Dawley Rats

ABSTRACT Introduction Combat injuries are complex and multimodal. Most injuries to the extremities occur because of explosive devices such as improvised explosive devices. Blast exposure dramatically increases the risk of infection in combat wounds, and there is limited available information on the best antibiotic treatments for these injuries. We previously demonstrated that mice exposed to blast displayed a delayed clearance of cefazolin from the plasma and liver; further semi-mechanistic modeling determined that cefazolin concentrations in the skin of these mice were reduced. Our objective was to investigate the effects of blast on the pharmacokinetics of antibiotics of different types used for the treatment of combat wounds in the rat model. Materials and Methods Male Sprague Dawley rats were exposed to blast overpressure followed by injection of a bolus of animal equivalent doses of an antibiotic (cefazolin, cefepime, ertapenem, or clindamycin) into the tail vein at 1-hour post-blast exposure. Blood was collected at predetermined time points via repeated sampling from the tail vein. Animals were also euthanized at predetermined time points, at which time liver, kidney, skin, and blood via cardiac puncture were collected. Antibiotic concentrations were determined by ultra-performance liquid chromatography–tandem mass spectrometry. Results Blast-exposed rats exhibited a similar rate of clearance compared to non-blasted rats in the blood, liver, kidney, and skin, which is inconsistent with the data regarding cefazolin in blast-exposed mice. Conclusions Our results in rats do not recapitulate our previous observation of delayed cefazolin clearance in mice following the blast overpressure exposure. Although using rats permitted us to collect multiple blood samples from the same animals, rats may not be a suitable model for measuring the pharmacokinetics of antibiotics following blast. The interpretation of the results may be challenging because of variation in data among rat subjects in the same sample groups.

General & Internal Medicine↗
DOE OSTI2018

Aging Exacerbates Neuroinflammatory Outcomes Induced by Acute Ozone Exposure

The role of environmental stressors, particularly exposure to air pollution, in the development of neurodegenerative disease remains underappreciated. We examined the neurological effects of acute ozone (O 3 ) exposure in aged mice, where increased blood brain barrier (BBB) permeability may confer vulnerability to neuroinflammatory outcomes. C 57 BL/6 male mice, aged 8-10 weeks or 12–18 months were exposed to either filtered air (FA) or 1.0 ppm O 3 for 4 hours; animals received a single IP injection of sodium fluorescein (FSCN) 20 hours post-exposure. One-hour post-FSCN injection, animals were transcardially perfused for immunohistochemical analysis of BBB permeability. β-amyloid protein expression was assessed via ELISA. Flow cytometric characterization of infiltrating immune cells, including neutrophils, macrophages, and microglia populations was performed 20 hours post-O 3 exposure. Flow cytometry analysis of brains revealed increased microglia “activation” and presentation of CD11b, F4/80 and MHCII in aged animals relative to younger ones; these age-induced differences were potentiated by acute O 3 exposure. Cortical and limbic regions in aged brains had increased reactive microgliosis and β-amyloid protein expression after O 3 insult. The aged cerebellum was particularly vulnerable to acute O 3 exposure with increased populations of infiltrating neutrophils, peripheral macrophages/monocytes, and Ly6C + inflammatory monocytes after insult, which were not significantly increased in the young cerebellum. O 3 exposure increased the penetration of FSCN beyond the BBB, the infiltration of peripheral immune cells, and reactive gliosis of microglia. Furthermore, the aged BBB is vulnerable to insult and becomes highly penetrable in response to O 3 exposure, leading to greater neuroinflammatory outcomes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Anticonvulsant drug polytherapy stops status epilepticus and prevents neuronal loss in soman‐exposed rats

Introduction When treatment of status epilepticus (SE) is delayed, seizures become self‐sustaining and refractory to benzodiazepine therapy. Chemical warfare nerve agents (CWNAs), such as soman(GD), increase acetylcholine through inhibition of acetylcholine sterase and can lead to SE if seizures are not treated quickly and controlled. Prolonged seizures may lead to extensive neuropathology, spontaneous recurrent seizures and long‐term performance deficits. To identify a better treatment against pharmacoresistant seizures caused by GD exposure, we are using combinations of drugs aimed at reversing the effects of maladaptive receptor trafficking that follows CWNA exposure. Methods Rats were implanted with telemetry transmitters for continuous monitoring of EEG, body temperature and activity. After surgical recovery, rats were exposed to 1.2 LD 50 GD and treated 1 min later with atropine sulfate and the oxime HI‐6 and then 40 min after seizure onset with the anticonvulsant phenobarbital with or without the NMDA antagonist ketamine (PHE/KET), the benzodiazepine midazolam (PHE/MDZ) or a combination of all three drugs (PHE/KET/MDZ).Two weeks after exposure, rat brains were sectioned and stained for neuropathology assessments. Results Triple therapy with PHE/KET/MDZ reduced total time spent in seizures (SE +early recurrent seizures) in the first 72 h and reduced the number of spontaneous recurrent seizures compared to midazolam monotherapy. Tripletherapy also reduced the duration of toxic signs in the hours following GD‐exposure and prevented the development of hyperactivity that occurs in the weeks following exposure compared to GD/MDZ monotherapy. In addition, tripletherapy reduced loss of neurons in the piriform cortex and thalamus compared to GD/MDZ monotherapy. Conclusion Triple therapy with PHE/KET/MDZ hadanticonvulsant, antiepileptic, and neuroprotective effects compared with midazolammonotherapy in GD‐exposed rats. Triple therapy may be a highly effective approach against pharmacoresistant seizures, such as those caused by GD exposure, and may allow for administration of lower doses, resulting in fewer side effects than are often seen with large doses of individual drug therapies. Disclaimer: The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of the Army, Department of Defense, or the U.S. Government. The experimental protocol was approved by the Animal Care and Use Committee at the United States Army Medical Research Institute of Chemical Defense and all procedures were conducted in accordance with the principles stated in the Guide for the Care and Use of Laboratory Animals and the Animal Welfare Act of 1966 (P.L. 89‐544), as amended. Support or Funding Information KatieWalker, Erica Kundrick and Sean O'Brien were supported in part by an appointment to the Research Participation Program for the U.S. Army Medical Research and Materiel Command administered by the Oak Ridge Institute for Science and Education through an agreement between the U.S. Department of Energy and U.S. Army Medical Research and Materiel Command. This research was supported by the NIH U01 to Dr. Claude Wasterlain.

Stone, Michael↗
DOE OSTI2025

The Vertebrate Breed Ontology: Toward Effective Breed Data Standardization

Abstract Background Limited universally-adopted data standards in veterinary medicine hinder data interoperability and therefore integration and comparison; this ultimately impedes the application of existing information-based tools to support advancement in diagnostics, treatments, and precision medicine. Hypothesis/Objectives A single, coherent, logic-based standard for documenting breed names in health, production, and research-related records will improve data use capabilities in veterinary and comparative medicine. Animals No live animals were used. Methods The Vertebrate Breed Ontology (VBO) was created from breed names and related information compiled from the Food and Agriculture Organization of the United Nations, breed registries, communities, and experts, using manual and computational approaches. Each breed is represented by a VBO term that includes breed information and provenance as metadata. VBO terms are classified using description logic to allow computational applications and Artificial Intelligence–readiness. Results VBO is an open, community-driven ontology representing over 19 500 livestock and companion animal breed concepts covering 49 species. Breeds are classified based on community and expert conventions (e.g., cattle breed) and supported by relations to the breed's genus and species indicated by National Center for Biotechnology Information (NCBI) Taxonomy terms. Relationships between VBO terms (e.g., relating breeds to their foundation stock) provide additional context to support advanced data analytics. VBO term metadata includes synonyms, breed identifiers/codes, and attributed cross-references to other databases. Conclusion and Clinical Importance The adoption of VBO as a standard for breed names in databases and veterinary electronic health records enhances veterinary data interoperability and computability, supporting precision medicine.

Veterinary Sciences↗
DOE OSTI2018

Nudge-nudge, WNK-WNK (kinases), say no more?

WITH NO LYSINE (WNK) kinases are serine/threonine kinases uniquely characterized by an anomalous placement of a catalytic lysine, hence their moniker. In animals, WNK protein kinases play critical roles in protein trafficking of components that mediate renal ion transport processes and regulate osmoregulation of cell volume. In plants, the WNK kinase gene family is larger and more diverse. Recent studies revealed WNK kinase roles in orchestrating the trafficking of an ion channel, a lipid kinase complex in animals, and a heterotrimeric G protein signaling component in plants that is necessary for signal transduction. For this reason, new attention is geared toward investigating the mechanisms adopted by WNK kinases to nudge intracellular proteins to their destinations. In this review, the functions of WNK kinases in protein trafficking are derived from what we have learned from the model organism Arabidopsis thaliana. To place this new idea in context, we provide the predicted WNK kinase structures, their predicted expression patterns, a speculated evolutionary pathway, and the regulatory roles of plant WNKs in transport processes and other physiologies. We brazenly predict that the WNK kinases in both plants and animals will soon be recognized as a nexus for trafficking-based signal transduction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Plant‐made E2 glycoprotein single‐dose vaccine protects pigs against classical swine fever

Abstract Classical Swine Fever Virus ( CSFV ) causes classical swine fever, a highly contagious hemorrhagic fever affecting both feral and domesticated pigs. Outbreaks of CSF in Europe, Asia, Africa and South America had significant adverse impacts on animal health, food security and the pig industry. The disease is generally contained by prevention of exposure through import restrictions ( e.g . banning import of live pigs and pork products), localized vaccination programmes and culling of infected or at‐risk animals, often at very high cost. Current CSFV ‐modified live virus vaccines are protective, but do not allow differentiation of infected from vaccinated animals ( DIVA ), a critical aspect of disease surveillance programmes. Alternatively, first‐generation subunit vaccines using the viral protein E2 allow for use of DIVA diagnostic tests, but are slow to induce a protective response, provide limited prevention of vertical transmission and may fail to block viral shedding. CSFV E2 subunit vaccines from a baculovirus/insect cell system have been developed for several vaccination campaigns in Europe and Asia. However, this expression system is considered expensive for a veterinary vaccine and is not ideal for wide‐spread deployment. To address the issues of scalability, cost of production and immunogenicity, we have employed an Agrobacterium ‐mediated transient expression platform in Nicotiana benthamiana and formulated the purified antigen in novel oil‐in‐water emulsion adjuvants. We report the manufacturing of adjuvanted, plant‐made CSFV E2 subunit vaccine. The vaccine provided complete protection in challenged pigs, even after single‐dose vaccination, which was accompanied by strong virus neutralization antibody responses.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Monte Carlo simulation of a compact microbeam radiotherapy system based on carbon nanotube field emission technology

Purpose: Microbeam radiation therapy (MRT) is an experimental radiotherapy technique that has shown potent antitumor effects with minimal damage to normal tissue in animal studies. This unique form of radiation is currently only produced in a few large synchrotron accelerator research facilities in the world. To promote widespread translational research on this promising treatment technology we have proposed and are in the initial development stages of a compact MRT system that is based on carbon nanotube field emission x-ray technology. We report on a Monte Carlo based feasibility study of the compact MRT system design. Methods: Monte Carlo calculations were performed using EGSnrc-based codes. The proposed small animal research MRT device design includes carbon nanotube cathodes shaped to match the corresponding MRT collimator apertures, a common reflection anode with filter, and a MRT collimator. Each collimator aperture is sized to deliver a beam width ranging from 30 to 200 {mu}m at 18.6 cm source-to-axis distance. Design parameters studied with Monte Carlo include electron energy, cathode design, anode angle, filtration, and collimator design. Calculations were performed for single and multibeam configurations. Results: Increasing the energy from 100 kVp to 160 kVp increased the photon fluence through the collimator by a factor of 1.7. Both energies produced a largely uniform fluence along the long dimension of the microbeam, with 5% decreases in intensity near the edges. The isocentric dose rate for 160 kVp was calculated to be 700 Gy/min/A in the center of a 3 cm diameter target. Scatter contributions resulting from collimator size were found to produce only small (<7%) changes in the dose rate for field widths greater than 50 {mu}m. Dose vs depth was weakly dependent on filtration material. The peak-to-valley ratio varied from 10 to 100 as the separation between adjacent microbeams varies from 150 to 1000 {mu}m. Conclusions: Monte Carlo simulations demonstrate that the proposed compact MRT system design is capable of delivering a sufficient dose rate and peak-to-valley ratio for small animal MRT studies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Two-dimensional inverse planning and delivery with a preclinical image guided microirradiator

Purpose: Recent advances in preclinical radiotherapy systems have provided the foundation for scaling many of the elements of clinical radiation therapy practice to the dimensions and energy demanded in small animal studies. Such systems support the technical capabilities to accurately deliver highly complex dose distributions, but methods to optimize and deliver such distributions remain in their infancy. This study developed an optimization method based on empirically measured two-dimensional dose kernel measurements to deliver arbitrary planar dose distributions on a recently developed small animal radiotherapy platform.Methods: A two-dimensional dose kernel was measured with repeated radiochromic film measurements for the circular 1 mm diameter fixed collimator of the small animal radiotherapy system at 1 cm depth in a solid water phantom. This kernel was utilized in a sequential quadratic programming optimization framework to determine optimal beam positions and weights to deliver an arbitrary desired dose distribution. The positions and weights were then translated to a set of stage motions to automatically deliver the optimized dose distribution. End-to-end efficacy of the framework was quantified through five repeated deliveries of two dosimetric challenges: (1) a 5 mm radius bullseye distribution, and (2) a “sock” distribution contained within a 9 × 13 mm bounding box incorporating rectangular, semicircular, and exponentially decaying geometric constructs and a rectangular linear dose gradient region. These two challenges were designed to gauge targeting, geometric, and dosimetric fidelity.Results: Optimization of the bullseye and sock distributions required 2.1 and 5.9 min and utilized 50 and 77 individual beams for delivery, respectively. Automated delivery of the resulting optimized distributions, validated using radiochromic film measurements, revealed an average targeting accuracy of 0.32 mm, and a dosimetric delivery error along four line profiles taken through the sock distribution of 3.9%. Mean absolute delivery error across the 0–1 Gy linear dose gradient over 7.5 mm was 0.01 Gy.Conclusions: The work presented here demonstrates the potential for complex dose distributions to be planned and automatically delivered with millimeter scale heterogeneity at submillimeter accuracy. This capability establishes the technical foundation for preclinical validation of biologically guided radiotherapy investigations and development of unique radiobiological experiments.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2014

Effects of reflector and crystal surface on the performance of a depth-encoding PET detector with dual-ended readout

Purpose: Depth encoding detectors are required to improve the spatial resolution and spatial resolution uniformity of small animal positron emission tomography (PET) scanners, as well as dedicated breast and brain scanners. Depth of interaction (DOI) can be measured by using dual-ended readout of lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiodes. Inter-crystal reflectors and crystal surface treatments play important roles in determining the performance of dual-ended detectors. In this paper, the authors evaluated five LSO arrays made with three different intercrystal reflectors and with either polished or unpolished crystal surfaces. Methods: The crystal size in all arrays was 1.5 mm, which is typical of the detector size used in small animal and dedicated breast scanners. The LSO arrays were measured with dual-ended readout and were compared in terms of flood histogram, energy resolution, and DOI resolution performance. Results: The four arrays using enhanced specular reflector (ESR) and Toray reflector provided similar quality flood histograms and the array using Crystal Wrap reflector gave the worst flood histogram. The two arrays using ESR reflector provided the best energy resolution and the array using Crystal Wrap reflector yielded the worst energy resolution. All arrays except the polished ESR array provided good DOI resolution ranging from 1.9 mm to 2.9 mm. DOI resolution improved as the gradient in light collection efficiency with depth (GLCED) increased. The geometric mean energies were also calculated for these dual-ended readout detectors as an alternative to the conventional summed total energy. It was shown that the geometric mean energy is advantageous in that it provides more uniform photopeak amplitude at different depths for arrays with high GLCED, and is beneficial in event selection by allowing a fixed energy window independent of depth. A new method of DOI calculation that improved the linearity of DOI ratio vs depth and simplifies the DOI calibration procedure also was developed and tested. Conclusions: The results of these studies provide useful guidance in selecting the proper reflectors and crystal surface treatments when LSO arrays are used for high-resolution PET applications in small animal scanners or dedicated breast and brain scanners.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-463: Quantification of Rotational Variation in Mouse Setup for IGRT

Purpose: New small-animal irradiators include extremely precise IGRT capabilities. However, mouse immobilization and localization remains a challenge. In particular, unlike week-to-week translational displacements, rotational changes in positioning are not easily corrected for in subject setup. Using two methods of setup, we aim to quantify week-to-week rotational variation in mice for the purpose of IGRT planning in small animal studies. Methods: Ten mice were imaged weekly using breath-hold CBCT (X-RAD 225 Cx), with the mouse positioned in a half-pipe support, providing 40 scans. A second group of two mice were positioned in a 3D printed immobilization device, which was created using a CT from a similarly shaped mouse, providing 10 scans. For each mouse, the first image was taken to be the reference image. Subsequent CT images were then rigidly registered, based on bony anatomy. Rotations in the axial (roll), sagittal (pitch), and coronal (yaw) planes were recorded and used to quantify variation in angular setup. Results: For the mice imaged in the half pipe, average magnitude of roll was found to be 5.4±4.6° (range: −12.9:18.86°), of pitch 1.6±1.3° (range: −1.4:4.7°), and of yaw 1.9±1.5° (range −5.4:1.1°). For the mice imaged in the printed setup; average magnitude of roll was found to be 0.64±0.6° (range: −2.1:1.0°), of pitch 0.6±0.4° (range: 0.0:1.3°), and of yaw 0.2±0.1° (range: 0.0:0.4°). The printed setup provided reduction in roll, pitch, and yaw by 88, 62, and 90 percent, respectively. Conclusion: For the typical setup routine, roll in mouse position is the dominant source of rotational variation. However, when a printed device was used, drastic improvements in mouse immobilization were seen. This work provides a promising foundation for mouse immobilization, required for full scale small animal IGRT. Currently, we are making improvements to allo±w the use of a similar system for MR, PET, and bioluminescence.

60 APPLIED LIFE SCIENCES↗