bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Monte Carlo estimation of effective dose in chest tomosynthesis
Authors: Sabol John M. 
Published: November 2009

Purpose:The recent introduction of digital tomosynthesis imaging into routine clinical use has enabled the acquisition of volumetric patient data within a standard radiographic examination. Tomosynthesis requires the acquisition of multiple projection views, requiring additional dose compared to a standard projection examination. Knowledge of the effective dose is needed to make an appropriate decision between standard projection, tomosynthesis, and CT for thoracic x‐ray examinations. In this article, the effective dose to the patient of chest tomosynthesis is calculated and compared to a standard radiographic examination and to values published for thoracic CT.Methods:Radiographic technique data for posterior‐anterior (PA) and left lateral (LAT) radiographic chest examinations of medium‐sized adults was obtained from clinical sites. From these data, the average incident air kerma for the standard views was determined. A commercially available tomosynthesis system was used to define the acquisition technique and geometry for each projection view. Using Monte Carlo techniques, the effective dose of the PA, LAT, and each tomosynthesis projection view was calculated. The effective dose for all projections of the tomosynthesis sweep was summed and compared to the calculated PA and LAT values and to the published values for thoracic CT.Results:The average incident air kerma for the PA and left lateral clinical radiographic examinations were found to be 0.10 and, respectively. The effective dose for the PA view of a patient of the size of an average adult male was determined to be (ICRP 60) [ (ICRP 103)]. For the left lateral view of the same sized patient, the effective dose was determined to be (ICRP 60) [ (ICRP 103)]. The cumulative mA s for a tomosynthesis examination is recommended to be ten times the mA s of the PA image. With this technique, the effective dose for an average tomosynthesis examination was calculated to be (ICRP60) [ (ICRP103)]. This is less than 75% of that predicted by scaling of the PA mA s ratio. This lower dose was due to changes in the focal‐spot‐to‐skin distance, effective changes in collimation with projection angle, rounding down of the mA s step, and variations in organ exposure to the primary x‐ray beam for each view. Large errors in dose estimation can occur if these factors are not accurately modeled.Conclusions:The effective dose of a chest examination with this chest tomosynthesis system is about twice that of a two‐view chest examination and less than 2% of the published average values for thoracic CT. It is shown that complete consideration of the tomosynthesis acquisition technique and geometry is required for accurate determination of the effective dose to the patient. Tomosynthesis provides three‐dimensional imaging at a dose level comparable to a two‐view chest x‐ray examination and may provide a low dose alternative to thoracic CT for obtaining depth information in chest imaging.
Energy dependence of EBT‐1 radiochromic film response for photon and electron beams readout by a flatbed scanner
Authors: Richter Christian , Pawelke Jörg , Karsch Leonhard , Woithe Julia 
Published: November 2009

Purpose:The aim of this article is to investigate the energy dependence of the radiochromic film type, Gafchromic™ EBT‐1, when scanned with a flatbed scanner for film readout.Methods:Dose response curves were determined for 12 different beam qualities ranging from a x‐ray beam to a x‐ray beam and include also two high energy electron beam qualities (6 and ). The dose responses measured as net optical density (netOD) for the different beam qualities were normalized to the response of a reference beam quality .Results:A strong systematic energy dependence of the film response was found. The lower the effective beam energy, the less sensitive the EBT‐1 films get. The maximum decrease in dose for the same film response between the and beam qualities was 44%. Additionally, a difference in energy dependence for different doses was discovered, meaning that higher doses show a smaller dependency on energy than lower doses. The maximum decrease in the normalized netOD was found to be 25% for a dose of relative to the normalized netOD for . Moreover, a scaling procedure is introduced, allowing the correction of the energy dependence for the investigated beam qualities and also for comparable x‐ray beam qualities within the energy range studied.Conclusions:A strong energy dependence for EBT‐1 radiochromic films was found. The films were readout with a flatbed scanner. If the effective beam energy is known, the energy dependence can be corrected with the introduced scaling procedure. Further investigation of the influence of the spectral band of the readout device on energy dependence is needed to understand the reason for the different energy dependences found in this and previous works.
Trial of a proposed protocol for constancy control of digital mammography systems
Authors: Pedersen Kristin , Landmark Ingrid Dypvik 
Published: November 2009

Purpose:Evaluate the utility of tests in a proposed protocol for constancy control of digital mammography systems.Methods:The protocol contained tests for image acquisition, mechanical function and safety, monitors and printers, and viewing conditions. Nine sites with digital systems from four equipment manufacturers were recruited. Dedicated PMMA test objects and Excel spreadsheets were developed. Quantitative measurements were done on processed images for systems where these images were the ones most readily available. For daily assessment of the automatic exposure control system, a homogeneous PMMA phantom was exposed under clinical conditions. The mAs and signal to noise ratio (SNR) were recorded, the deviation from a target value calculated, and the resulting image inspected for artifacts. For thickness tracking, the signal difference to noise ratio obtained for three thicknesses was calculated. Detector uniformity was assessed through comparison of SNR values for regions of interest in the center and corners of an image of a homogeneous test object. Mechanical function and safety control included a compression test, a checklist for mechanical aspects, and control of field alignment. Monitor performance was evaluated by visual inspection of the AAPM TG 18 QC test image [E. Samei et al., “Assessment of display performance for medical imaging systems,” Task Group 18 (Madison, WI, April 2005)].Results:For quantitative parameters, target values and tolerance limits were established. Test results exceeding the limits were registered. Most systems exhibited stable mAs values, indicating that the tolerance limit of was readily achievable. The SNR also showed little variation, indicating that the tolerance limit of was too wide. At one site, a defective grid caused artifacts that were visible in the test images. The monitor controls proved more difficult to implement due to both difficulties importing and displaying the test image, and the radiographic technologists not getting necessary access to the reading stations.Conclusions:The proposed tests could easily be performed by trained radiographic technologists and within a time frame comparable to similar programs for analog systems. Tests with quantitative measures were more readily performed than procedures that required a subjective evaluation. Several of the proposed tests revealed equipment performance that required intervention, and which would otherwise have gone unnoticed. They therefore defend a place in a vendor‐independent constancy control protocol.
Reducing radiation dose to selected organs by selecting the tube start angle in MDCT helical scans: A Monte Carlo based study
Authors: Zhang Di , Zankl Maria , DeMarco John J. , Cagnon Chris H. , Angel Erin , Turner Adam C. , McNitt‐Gray Michael F. 
Published: November 2009

Purpose:Previous work has demonstrated that there are significant dose variations with a sinusoidal pattern on the peripheral of a CTDI 32 cm phantom or on the surface of an anthropomorphic phantom when helical CT scanning is performed, resulting in the creation of “hot” spots or “cold” spots. The purpose of this work was to perform preliminary investigations into the feasibility of exploiting these variations to reduce dose to selected radiosensitive organs solely by varying the tube start angle in CT scans.Methods:Radiation dose to several radiosensitive organs (including breasts, thyroid, uterus, gonads, and eye lenses) resulting from MDCT scans were estimated using Monte Carlo simulation methods on voxelized patient models, including GSF's Baby, Child, and Irene. Dose to fetus was also estimated using four pregnant female models based on CT images of the pregnant patients. Whole‐body scans were simulated using 120 kVp, 300 mAs, both 28.8 and 40 mm nominal collimations, and pitch values of 1.5, 1.0, and 0.75 under a wide range of start angles (0°–340° in 20° increments). The relationship between tube start angle and organ dose was examined for each organ, and the potential dose reduction was calculated.Results:Some organs exhibit a strong dose variation, depending on the tube start angle. For small peripheral organs (e.g., the eye lenses of the Baby phantom at pitch 1.5 with 40 mm collimation), the minimum dose can be 41% lower than the maximum dose, depending on the tube start angle. In general, larger dose reductions occur for smaller peripheral organs in smaller patients when wider collimation is used. Pitch 1.5 and pitch 0.75 have different mechanisms of dose reduction. For pitch 1.5 scans, the dose is usually lowest when the tube start angle is such that the x‐ray tube is posterior to the patient when it passes the longitudinal location of the organ. For pitch 0.75 scans, the dose is lowest when the tube start angle is such that the x‐ray tube is anterior to the patient when it passes the longitudinal location of the organ.Conclusions:Helical MDCT scanning at pitch 1.5 and pitch 0.75 results in “cold spots” and “hot spots” that are created both at surface and in‐depth locations within patients. For organs that have a relatively small longitudinal extent, dose can vary considerably with different start angles. While current MDCT systems do not provide the user with the ability to control the tube start angle, these results indicate that in these specific situations (pitch 1.5 or pitch 0.75, small organs and especially small patients), there could be significant dose savings to organs if that functionality would be provided.
SCY-635, a Novel Nonimmunosuppressive Analog of Cyclosporine That Exhibits Potent Inhibition of Hepatitis C Virus RNA ReplicationIn Vitro
Authors: Hopkins Sam , Scorneaux Bernard , Huang Zhuhui , Murray Michael G. , Wring Stephen , Smitley Craig , Harris Richard , Erdmann Frank , Fischer Gunter , Ribeill Yves 
Published: November 2009

ABSTRACTSCY-635 is a novel nonimmunosuppressive cyclosporine-based analog that exhibits potent suppression of hepatitis C virus (HCV) replicationin vitro. SCY-635 inhibited the peptidyl prolyl isomerase activity of cyclophilin A at nanomolar concentrations but showed no detectable inhibition of calcineurin phosphatase activity at concentrations up to 2 μM. Metabolic studies indicated that SCY-635 did not induce the major cytochrome P450 enzymes 1A2, 2B6, and 3A4. SCY-635 was a weak inhibitor and a poor substrate for P-glycoprotein. Functional assays with stimulated Jurkat cells and stimulated human peripheral blood mononuclear cells indicated that SCY-635 is a weaker inhibitor of interleukin-2 secretion than cyclosporine. A series of two-drug combination studies was performedin vitro. SCY-635 exhibited synergistic antiviral activity with alpha interferon 2b and additive antiviral activity with ribavirin. SCY-635 was shown to be orally bioavailable in multiple animal species and produced blood and liver concentrations of parent drug that exceeded the 50% effective dose determined in the bicistronic con1b-derived replicon assay. These results suggest that SCY-635 warrants further investigation as a novel therapeutic agent for the treatment of individuals who are chronically infected with HCV.
Activity of a New Antipseudomonal Cephalosporin, CXA-101 (FR264205), against Carbapenem-Resistant and Multidrug-Resistant
Pseudomonas aeruginosa
Clinical Strains
Authors: Juan Carlos , Zamorano Laura , Pérez José L. , Ge Yigong , Oliver Antonio 
Published: November 2009

ABSTRACT

The activity of the new cephalosporin CXA-101 (CXA), previously designated FR264205, was evaluated against a collection of 236 carbapenem-resistant
P. aeruginosa
isolates, including 165 different clonal types, from a Spanish multicenter (127-hospital) study. The MICs of CXA were compared to the susceptibility results for antipseudomonal penicillins, cephalosporins, carbapenems, aminoglycosides, and fluoroquinolones. The MIC of CXA in combination with tazobactam (4 and 8 μg/ml) was determined for strains with high CXA MICs. The presence of acquired β-lactamases was investigated by isoelectric focusing and PCR amplification followed by sequencing. Additional β-lactamase genes were identified by cloning and sequencing. The CXA MIC
50
/MIC
90
for the complete collection of carbapenem-resistant
P. aeruginosa
isolates was 1/4 μg/ml, with 95.3% of the isolates showing an MIC of ≤8 μg/ml. Cross-resistance with any of the antibiotics tested was not observed; the MIC
50
/MIC
90
of CXA-101 was still 1/4 when multidrug-resistant (MDR) strains (42% of all tested isolates) or AmpC-hyperproducing clones (53%) were analyzed. Almost all (10/11) of the strains showing a CXA MIC of >8 μg/ml produced a horizontally acquired β-lactamase, including the metallo-β-lactamase (MBL) VIM-2 (one strain), the extended-spectrum β-lactamase (ESBL) PER-1 (one strain), several extended-spectrum OXA enzymes (OXA-101 [one strain], OXA-17 [two strains], and a newly described OXA-2 derivative [W159R] designated OXA-144 [four strains]), and a new BEL variant (BEL-3) ESBL (one strain), as identified by cloning and sequencing. Synergy with tazobactam in these 11 strains was limited, although 8 μg/ml reduced the mean CXA MIC by 2-fold. CXA is highly active against carbapenem-resistant
P. aeruginosa
isolates, including MDR strains. Resistance was restricted to still-uncommon strains producing an acquired MBL or ESBL.
Pharmacokinetics of Ertapenem following Intravenous and Subcutaneous Infusions in Patients
Authors: Frasca Denis , Marchand Sandrine , Petitpas Franck , Dahyot-Fizelier Claire , Couet William , Mimoz Olivier 
Published: November 2009

ABSTRACT
Steady-state pharmacokinetics of ertapenem were compared in patients after 1-g intravenous and subcutaneous (s.c.) infusions. Bioavailability was 99% ± 18% after s.c. administration, but peaks were reduced by about (43 ± 29 versus 115 ± 28 μg/ml) and times to peak were delayed. Simulations based on unbound concentrations show that time over the MIC should always be longer than 30% to 40% of the dosing interval, suggesting that s.c. infusion could be an alternative in patients with reduced vascular access.
Activity and Toxicity of Farnesol towards
Candida albicans
Are Dependent on Growth Conditions
Authors: Langford Melanie L. , Hasim Sahar , Nickerson Kenneth W. , Atkin Audrey L. 
Published: November 2009

ABSTRACT

Farnesol interacts with
Candida albicans
as both a quorum-sensing molecule and toxic agent, but confusion abounds regarding which conditions promote these distinct responses. Farnesol sensitivity was measured when inoculum cell history and size, temperature, and growth media were altered. Parameters for farnesol tolerance/sensitivity were defined, validating previous studies and identifying new variables, such as energy availability. This study clearly defines what farnesol concentrations are lethal to
C. albicans
, based on environmental conditions.
Campylobacter jejuni
and
Campylobacter coli
Genotyping by High-Resolution Melting Analysis of a
flaA
Fragment
Authors: Merchant-Patel Shreema , Blackall Patrick J. , Templeton Jillian , Price Erin P. , Tong Steven Y. C. , Huygens Flavia , Giffard Philip M. 
Published: November 2009

ABSTRACT

The highly variable flagellin-encoding
flaA
gene has long been used for genotyping
Campylobacter jejuni
and
Campylobacter coli
. High-resolution melting (HRM) analysis is emerging as an efficient and robust method for discriminating DNA sequence variants. The objective of this study was to apply HRM analysis to
flaA
-based genotyping. The initial aim was to identify a suitable
flaA
fragment. It was found that the PCR primers commonly used to amplify the
flaA
short variable repeat (SVR) yielded a mixed PCR product unsuitable for HRM analysis. However, a PCR primer set composed of the upstream primer used to amplify the fragment used for
flaA
restriction fragment length polymorphism (RFLP) analysis and the downstream primer used for
flaA
SVR amplification generated a very pure PCR product, and this primer set was used for the remainder of the study. Eighty-seven
C. jejuni
and 15
C. coli
isolates were analyzed by
flaA
HRM and also partial
flaA
sequencing. There were 47
flaA
sequence variants, and all were resolved by HRM analysis. The isolates used had previously also been genotyped using single-nucleotide polymorphisms (SNPs), binary markers, CRISPR HRM, and
flaA
RFLP.
flaA
HRM analysis provided resolving power multiplicative to the SNPs, binary markers, and CRISPR HRM and largely concordant with the
flaA
RFLP. It was concluded that HRM analysis is a promising approach to genotyping based on highly variable genes.
Effectiveness of Liquid Soap and Hand Sanitizer against Norwalk Virus on Contaminated Hands
Authors: Liu Pengbo , Yuen Yvonne , Hsiao Hui-Mien , Jaykus Lee-Ann , Moe Christine 
Published: November 2009

ABSTRACT

Disinfection is an essential measure for interrupting human norovirus (HuNoV) transmission, but it is difficult to evaluate the efficacy of disinfectants due to the absence of a practicable cell culture system for these viruses. The purpose of this study was to screen sodium hypochlorite and ethanol for efficacy against Norwalk virus (NV) and expand the studies to evaluate the efficacy of antibacterial liquid soap and alcohol-based hand sanitizer for the inactivation of NV on human finger pads. Samples were tested by real-time reverse transcription-quantitative PCR (RT-qPCR) both with and without a prior RNase treatment. In suspension assay, sodium hypochlorite concentrations of ≥160 ppm effectively eliminated RT-qPCR detection signal, while ethanol, regardless of concentration, was relatively ineffective, giving at most a 0.5 log
10
reduction in genomic copies of NV cDNA. Using the American Society for Testing and Materials (ASTM) standard finger pad method and a modification thereof (with rubbing), we observed the greatest reduction in genomic copies of NV cDNA with the antibacterial liquid soap treatment (0.67 to 1.20 log
10
reduction) and water rinse only (0.58 to 1.58 log
10
reduction). The alcohol-based hand sanitizer was relatively ineffective, reducing the genomic copies of NV cDNA by only 0.14 to 0.34 log
10
compared to baseline. Although the concentrations of genomic copies of NV cDNA were consistently lower on finger pad eluates pretreated with RNase compared to those without prior RNase treatment, these differences were not statistically significant. Despite the promise of alcohol-based sanitizers for the control of pathogen transmission, they may be relatively ineffective against the HuNoV, reinforcing the need to develop and evaluate new products against this important group of viruses.
Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods
Authors: Mormann Sascha , Dabisch Mareike , Becker Barbara 
Published: November 2009

ABSTRACT
Contaminated food is a significant vehicle for human norovirus transmission. The present study determined the effect of physicochemical treatments on the tenacity of infective human norovirus genogroup II in selected foods. Artificially contaminated produce was subjected to a number of processes used by the food industry for preservation and by the consumer for storage and preparation. Virus recovery was carried out by using ultrafiltration and was monitored by using bacteriophage MS2 as an internal process control. Norovirus was quantified by using monoplex one-step TaqMan real-time reverse transcription (RT)-PCR and an external standard curve based on recombinant RNA standards. An RNase pretreatment step was used to avoid false-positive PCR results caused by accessible RNA, which allowed detection of intact virus particles. Significant reductions in titers were obtained with heat treatments usually applied by consumers for food preparation (baking, cooking, roasting). Generally, processes used for preservation and storage, such as cooling, freezing, acidification (≥pH 4.5), and moderate heat treatments (pasteurization), appear to be insufficient to inactivate norovirus within a food matrix or on the surface of food. Besides data for persistence in processed food, comparable data for individual matrix-specific protective effects, recovery rates, and inhibitory effects on the PCRs were obtained in this study. The established procedure might be used for other noncultivable enteric RNA viruses that are connected to food-borne diseases. The data obtained in this study may also help optimize the process for inactivation of norovirus in food by adjusting food processing technologies and may promote the development of risk assessment systems in order to improve consumer protection.
Construction of a Nontoxigenic
Clostridium botulinum
Strain for Food Challenge Studies
Authors: Bradshaw Marite , Marshall Kristin M. , Heap John T. , Tepp William H. , Minton Nigel P. , Johnson Eric A. 
Published: November 2009

ABSTRACT

Clostridium botulinum
produces the most poisonous natural toxin known and is a perennial concern to the food industry and to regulatory agencies due to the potential threat of food-borne botulism. To ensure the botulinal safety of foods, rigorous food challenge testing to validate food-processing conditions and food formulations has been routinely performed. Detection of the botulinum neurotoxin is performed by using a mouse bioassay and/or
in vitro
assays. There has been considerable interest by the food industry and regulatory agencies in minimizing or even replacing the use of animals in these challenge studies. In addition, due to stringent select-agent regulations, the testing of various foods using toxigenic
C. botulinum
strains requires facilities and personnel that are certified for work with this organism. For this purpose we propose to generate sets of nontoxigenic
C. botulinum
strains from proteolytic and nonproteolytic groups that differ from the wild-type strains only by their inability to produce botulinum neurotoxin. In this initial study we describe the generation of a nontoxigenic mutant of
C. botulinum
strain 62A using the ClosTron mutagenesis system by inserting a group II intron into the botulinum neurotoxin type A gene (
bont/A
). The mutant clones were nontoxigenic as determined by Western blots and mouse bioassays but showed physiological characteristics, including growth properties and sporulation, that were similar to those of the parent strain in laboratory media. Additional studies will be required to evaluate comparable characteristics in various food matrices. The availability of suitable nontoxigenic
C. botulinum
strains for food challenge studies will be beneficial for enhancing the botulinal safety of foods as well as increasing the biosafety of workers and may eliminate the use of laboratory animals.