Multi-detector System Research Articles

Evaluation of gross radioactivity in foodstuffs

Abstract The paper presents the results of radiological investigations of food products sampled in the summer and fall of 2011 and 2012 in different parts of Van, Turkey. Gross radioactivity measurements in food products were evaluated. Food items were divided into eight groups: (1) water, (2) fish, (3) cheese products, (4) fruits, (5) vegetables, (6) herbs, (7) walnut and (8) rock salt. The levels of the gross alpha and gross beta radioactivity in all food samples varied widely ranging from 0.070 to 10.885 Bq/g and from 0.132 to 48.285 Bq/g on dry mass basis, respectively. In one sample, gross alpha and gross beta activity concentrations were found to be relatively high according to the other samples and in all samples, the gross alpha radioactivity was measured lower than the gross beta radioactivity. The gross α and gross β activities were measured by using α/β counter of the multi-detector low background system (PIC MPC-9604).

Validation of a method to differentiate arterial and venous vessels in CT perfusion data using linear combinations of quantitative time-density curve characteristics.

We aimed to develop and evaluate a new method that reliably differentiates between cerebral arteries and veins using voxel-wise CT-perfusion-derived parameters. Fourteen consecutive patients with suspected stroke but without pathological findings were examined on a multi-detector CT system: 32 dynamic phases (∆t = 1.5 s) during application of 35 mL iomeprol-350 were acquired at 80 kV/200mAs. Three hemodynamic parameters were calculated for 18 arterial and venous vessel segments: A (maximum of the time-density-curve), T (time-to-peak), and W (full-width-at-half-maximum). Using receiver operator characteristic (ROC) curve analysis and Fisher's linear discriminant analysis (FLDA), the performance of every classifier (A, T, W) and of all linear combinations for the differentiation of arterial and venous vessels was determined. A maximum area under the ROC-curve (AUC) of 0.945 (accuracy = 86.8%) was obtained using the FLDA combination of A&T or the triplet FLDA of A&T&W for the classification of venous and arterial vessels. The best single parameter was T with an AUC of 0.871 (accuracy = 79.0%), which performed significantly worse than the combination A&T (p < 0.001). Arteries and veins can be accurately differentiated based on dynamic CT perfusion data using the maximum of the time-density curve, its time-to-peak, its width, and FLDA combinations of these parameters, which yield accuracies up to 87%. • For classification of cerebral vasculature, time-to-peak has the best single-parameter accuracy. • Fisher's linear discriminant analysis improves the performance of the individual classifiers. • Combining signal maximum and time-to-peak parameters significantly increased the classifying potential. • Pre-processing of time-density-curves by Gaussian filtering or fitting can improve diagnostic accuracy.

HRCT in cystic fibrosis in patients with CFTR I1234V mutation: Assessment of scoring systems with low dose technique using multidetector system and correlation with pulmonary function tests.

Background and Aims:Pulmonary changes in patients with cystic fibrosis (CF) with CFTR I1234V mutation have not been extensively documented. Impact of geographic influence on phenotypical expression is largely unknown. This descriptive clinical study presents the high-resolution computed tomography (HRCT) pulmonary findings and computed tomography (CT) scoring with respect to pulmonary function tests (PFT) in a small subset of CF group.Materials and Methods:We examined 29 patients between 2 and 31 years of age with CFTR I1234V mutation. HRCT and PFT were performed within 2 weeks of each other. Imaging abnormalities on HRCT were documented and analyzed by utilizing the scoring system described by Bhalla et al., Brody et al., Helbich et al.,and Santamaria et al. Efficacy of the scoring system with respect to PFT was compared.Statistical Analysis:Inter-observer reliability of the scoring systems was tested using intraclass correlation (ICC) between the two observers. Spearman correlation coefficients were calculated between the scoring systems and between the scoring systems and PFT results.Results:In our study, right upper and middle lobes were the most frequently involved sites of involvement. Bronchiectasis and peribronchial thickening were the most frequent imaging findings. Scores with all four scoring systems were reproducible, with good ICC coefficient of 0.69. There was good agreement between senior radiologists in all scoring systems.Conclusion:We noted pulmonary imaging abnormalities in a large majority (96%) of our CF patients. There was no significant difference in the CT scores observed from various systems. The CT evaluation system by Broody is detailed and time consuming, and is ideal for research and academic setup. On the other hand, the systems by Bhalla and Santamaria are easy to use, quick, and equally informative. We found the scoring system by Santamaria preferable over that of Bhalla by virtue of additional points of evaluation and ease of use, and therefore better suited for busy clinical practice.

Spatial resolution measurement for iterative reconstruction by use of image-averaging techniques in computed tomography.

The purpose of our study was to investigate the validity of a spatial resolution measuring method that uses a combination of a bar-pattern phantom and an image-averaging technique, and to evaluate the spatial resolution property of iterative reconstruction (IR) images with middle-contrast (50 HU) objects. We used computed tomography (CT) images of the bar-pattern phantom reconstructed by the IR technology Adaptive Iterative Dose Reduction 3D (AIDR 3D), which was installed in the multidetector CT system Aquilion ONE (Toshiba Medical Systems, Otawara, Japan). The contrast of the bar-pattern image was set to 50 HU, which is considered to be a middle contrast that requires higher spatial resolution clinically. We employed an image-averaging technique to eliminate the influence of image noise, and we obtained averaged images of the bar-pattern phantom with sufficiently low noise. Modulation transfer functions (MTFs) were measured from the images. The conventional wire method was also used for comparison; in this method, AIDR 3D showed MTF values equivalent to those of filtered back projection. For the middle-contrast condition, the results showed that the MTF of AIDR 3D decreased with the strength of IR processing. Further, the MTF of AIDR 3D decreased with dose reduction. The image-averaging technique used was effective for correct evaluation of the spatial resolution for middle-contrast objects in IR images. The results obtained by our method clarified that the resolution preservation of AIDR 3D was not sufficient for middle-contrast objects.

238U and total radioactivity in drinking waters in Van province, Turkey

As part of the national survey to evaluate natural radioactivity in the environment, concentration levels of total radioactivity and natural uranium have been analysed in drinking water samples. A survey to study natural radioactivity in drinking waters was carried out in the Van province, East Turkey. Twenty-three samples of drinking water were collected in the Van province and analysed for total α, total β and 238U activity. The total α and total β activities were counted by using the α/β counter of the multi-detector low background system (PIC MPC-9604), and the 238U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2). The samples were categorised according to origin: tap, spring or mineral supply. The activity concentrations for total α were found to range from 0.002 to 0.030 Bq L−1 and for total β from 0.023 to 1.351 Bq L−1. Uranium concentrations ranging from 0.562 to 14.710 μg L−1 were observed in drinking waters. Following the World Health Organisation rules, all investigated waters can be used as drinking water.

Characterization of atherosclerotic plaque: a contrast‐detail study using multidetector and cone‐beam computed tomography

A Hindmarsh‐Rose model perceptibility phantom containing inserts with various in vitro atherosclerotic plaque compositions was constructed and imaged on a clinical 64 slice multidetector (MDCT) system using 80 and 120 kVp settings and two other cone‐beam (CBCT) systems at 80 kVp. Perceptibility of the simulated lipid‐fibrotic plaque solutions in the images was evaluated by six observers. The effective doses of the protocols employed were estimated using phantom CTDI‐vol measurements placed at identical settings. The CBCT system allowed reduction in effective dose in comparison with the conventional MDCT system for imaging of the carotid plaque phantoms without degrading image quality. The CBCT dose was less than MDCT, with a mean dose of 1.14±0.01 mSv and 1.11±0.02 mSv for MDCT using two measuring techniques vs. 0.35±0.01 mSv for CBCT. The image quality analysis showed no significant differences in the contrast‐detail (C‐D) curves of the best performing CBCT vs. clinical MDCT (p>0.05) using a Mann‐Whitney U test. Results indicate that low‐tube‐potential CBCT may produce comparable C‐D resolution for phantom‐based representations of soft plaque types with respect to MDCT systems. This study suggests that the utility of low kVp CT techniques for evaluating carotid vulnerable atherosclerotic plaque merits further study.PACS numbers: 87.53.Bn, 87.57.N‐, 87.57.Q‐, 87.57.cj

A Multi-detector NaI(Tl) Gamma-ray Spectrometry System for Investigation of Neutron Induced Capture and Fission Reactions

At the Joint Institute for Nuclear Research (JINR) Frank Laboratory of Neutron Physics (FLNP), a new multi-detector gamma-ray spectrometry system (MDGRSS) was constructed. It consists of 24 hexagonal NaI(Tl) detectors, arranged in two cylindrical arrays of variable diameter and distance between them. Test measurements with the MDGRSS are going on at one of the neutron beam-lines of the pulsed white-spectrum neutron source IREN. Some preliminary results from a measurement of the resonance-neutron flux density at IREN 60m flight-path station, using 181Ta(n,γ) reaction, are reported. In combination with a multi-section parallel-plate gas-ionization chamber as a fission fragment detector, positioned in the centre of the system, it is possible to investigate the neutron-induced capture and fission reactions on a number of heavy isotopes, important for fundamental and applied neutron and nuclear physics.

Investigation of the disappearance of collective motion in nuclei of mass A~120-130

A study of hot Giant Dipole Resonance (GDR) in nuclei of mass A=120130 in an excitation energy range from 150 to 330 MeV, where the GDR quenching is expected to arise, has been undertaken using the MEDEA multi-detector system. Hot nuclei were populated using complete and incomplete fusion reactions. The characterization of hot system was performed through the study of residue time of flight combined with the analysis of light charged energy spectra detected in coincidence. Gamma-ray energy spectra show an evolution of the GDR main features both in terms of width and multiplicity. Evidences of a saturation of gamma multiplicity appear at high excitation energy at variance with predictions of statistical model calculations. Gamma- ray energy spectra can been reproduced in a phenomenological way introducing in the statistical model a sharp suppression of the gamma-ray emission above E* = 240 MeV. A comparison of experimental data to models describing the GDR disappearance will be presented.

CT signs of right ventricular dysfunction correlated with echocardiography-derived pulmonary arterial systolic pressure: incremental value of the pulmonary arterial diameter index

To investigate and compare the potential of right to left ventricular volume (RVV/LVV) and diameter ratios (RVD/LVD) for the prediction of pulmonary arterial hypertension (PH) over 40 mmHg, and then to evaluate the incremental value of the pulmonary artery diameter index (PADi; PAD/body surface area) in the prediction of PH over 40 mHg. We correlated the followings on chest CT with same-day echocardiography-derived pulmonary arterial systolic pressure (PASP) in 139 patients (64.8 ± 15.4 years; 63 male): PADi, RVD/LVD on axial (RVD axial/LVD axial) and four chamber (RVD 4CH/LVD 4CH) views, and RVV/LVV. Those were then adjusted (multiplied) by PADi. Areas under the curves (AUC) for predicting PASP > 40 mmHg were calculated. All patients had undergone non-ECG-gated, contrast enhanced chest CT on a 64-slice multi-detector CT system. The correlation of PASP with RVV/LVV (R(2) = 0.45) was stronger than with RVD axial/LVD axial (R(2) = 0.28) and RVD 4CH/LVD 4CH (R(2) = 0.34). When adjusted by PADi, the correlation improved; R(2) = 0.55, 0.41 and 0.47, respectively. The AUC of adjusted RVV/LVV was significantly higher than those of other CT measurements (P < 0.05) excluding adjusted RVD 4CH/LVD 4CH (P = 0.08). With 18.80 as the cutoff, its sensitivity and specificity for predicting PH > 40 mmHg were 83 and 87 %, respectively. Ventricular volume is superior to ventricular diameter ratios in the prediction of PH > 40 mmHg with better correlation with PASP. PADi adds incremental value to these measurements in the prediction of PH > 40 mmHg. Of those, adjusted RVV/LVV is most reliable and predicts PH > 40 mmHg with fairly high sensitivity and specificity.

Detection and identification of large fragments from the partitioning of the 197Au + 197Au system at 23A MeV

First results of a study of partitioning of the nonfusing 197Au + 197Au system at an energy of 23A MeV are reported. A variety of light, medium and heavy fragments were detected and identified by using the 4π multidetector system CHIMERA (Charged Heavy Ion Mass and Energy Resolving Array). A new method of identification of low-energy fragments stopped in the silicon detectors, based on a precise time-of-flight analysis, is proposed. The method has been applied in a preliminary analysis of the 197Au + 197Au partitioning processes leading to the neck emission of intermediate mass fragments and sequential breakup of projectile-like or target-like fragments.

Performance of a high‐sensitivity dedicated cardiac SPECT scanner for striatal uptake quantification in the brain based on analysis of projection data

The authors have previously reported the advantages of high-sensitivity single-photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I-123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkinson disease (PD), as well as for monitoring progression of the disease. Realizing the full potential of DaTscan requires efficient estimation of striatal uptake from SPECT images. They have evaluated two SPECT systems, a conventional dual-head gamma camera with low-energy high-resolution collimators (conventional) and a dedicated high-sensitivity multidetector cardiac imaging system (dedicated) for imaging tasks related to PD. Cramer-Rao bounds (CRB) on precision of estimates of striatal and background activity concentrations were calculated from high-count, separate acquisitions of the compartments (right striata, left striata, background) of a striatal phantom. CRB on striatal and background activity concentration were calculated from essentially noise-free projection datasets, synthesized by scaling and summing the compartment projection datasets, for a range of total detected counts. They also calculated variances of estimates of specific-to-nonspecific binding ratios (BR) and asymmetry indices from these values using propagation of error analysis, as well as the precision of measuring changes in BR on the order of the average annual decline in early PD. Under typical clinical conditions, the conventional camera detected 2 M counts while the dedicated camera detected 12 M counts. Assuming a normal BR of 5, the standard deviation of BR estimates was 0.042 and 0.021 for the conventional and dedicated system, respectively. For an 8% decrease to BR = 4.6, the signal-to-noise ratio were 6.8 (conventional) and 13.3 (dedicated); for a 5% decrease, they were 4.2 (conventional) and 8.3 (dedicated). This implies that PD can be detected earlier with the dedicated system than with the conventional system; therefore, earlier identification of PD progression should be possible with the high-sensitivity dedicated SPECT camera.

산사 및 마늘 분말이 한우암소의 이산화탄소 및 메탄 발생량에 미치는 영향

ABSTRACT This study was conducted to investigate the effects of dietary garlic and may flower powder on CO 2 and CH 4 emission by Hanwoo cows fed TMR (Total Mixed Ration) based diet. Animals were housed in a hood-type respiration chamber and the environmental temperature was maintained at 20℃. Gases were measured for 24 hours using the multi-detector instrument gas monitoring system (Mamos-300, Australia). The treatments composed of groups with no intake of garlic and may flower powder (Control), with intake of garlic at 0.5% of DM (T1), with intake of garlic at 1% of DM (T2), with intake of may flower at 0.5% of DM (T3), with intake of may flower at 1% of DM (T4), with intake of garlic and may flower at 0.5% of DM (T5) and with intake of garlic and may flower at 1% of DM (T6). The results indicated that CO 2 emission in T3 was 53% lower than that of control (p<0.05), and CH 4 emissions was 57% lower than control (p<0.05). Also, the hourly pattern of CO 2 and CH 4 emissions in T3 showed the least difference with all treatments. Gas emissions pattern peaked after 1 hour of feeding and this gap was wider in the afternoon than in the morning hours.(

238U and 222Rn activity concentrations and total radioactivity levels in lake waters

The concentrations and distributions of natural radioactivity, uranium and radon in lake waters from around Van, Turkey were investigated with an aim of evaluating the environmental radioactivity. Fourteen lake waters were collected from different six lakes around Van (Turkey) to determine 238U, 222Rn and total alpha and total beta distributions in 2009. The total α and total β activities were counted by using α/β counter of the multi-detector low background system (PIC-MPC-9604) and the 238U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2) and radon concentrations were measured with the solid state nuclear track detector technique. The activity concentrations ranging from ND to 0.039 Bq L−1 and from 0.026 to 3.728 Bq L−1 for total alpha and beta, respectively, and uranium concentrations ranging from 0.083 to 3.078 μg L−1, and radon concentrations varying between 47.80 and 354.86 Bq m−3 were observed in the lake waters.

Spatial Distribution of Submarine Groundwater Discharge and Associated Nutrients within a Local Coastal Area

To understand the local-scale distribution of submarine groundwater discharge (SGD) and dissolved nutrients, a multiple-detector (222)Rn monitoring survey was undertaken along the Mt. Chokai volcanic coast in northern Japan. The surveys revealed that the highest SGD (calculated to be 6.2 × 10(4) m(3) d(-1), within an area of 2 × 10(4) m(2)) with the greatest nutrient fluxes (sum of NO(3)(-), NO(2)(-), and NH(4)(+) (DIN): 9.2 × 10(2) mol d(-1); PO(4)(3-) (DIP): 56 mol d(-1)) is present at the edge of the youngest volcanic lava flow in the area. Recharged groundwater transports nutrients through porous volcanic flows and discharges as SGD near shore. Our results demonstrate that the spatial distribution of SGD in the study area is closely regulated by the local geology and topography. Furthermore, we show that continuous (222)Rn monitoring with a multidetector system at boat speeds of 1-2 knots provides details at a scale one order of magnitude greater than has been reported previously. In addition, the results of our study suggest that SGD-borne DIP may play an important role in the important local oyster production.

Characterization of Silver Nanoparticle Products Using Asymmetric Flow Field Flow Fractionation with a Multidetector Approach – a Comparison to Transmission Electron Microscopy and Batch Dynamic Light Scattering

Due to the already prevalent and increasing use of silver-nanoparticle (Ag-NP) products and the raised concerns in particular for the aquatic environment, analytical techniques for the characterization of such products are of need. However, because Ag-NP products are of different compositions and polydispersities, analysis especially of the size distribution is challenging. In this work, an asymmetric flow field flow fractionation (A4F) multidetector system (UV/vis, light scattering, inductively coupled plasma mass spectrometry - ICPMS), in combination with a method to distinguish and quantify the particle and dissolved Ag fractions (ICPMS after ultracentrifugation), for the characterization of Ag-NP products with different degrees of polydispersities is presented. For validation and to outline benefits and limitations, results obtained from batch dynamic light scattering (batch-DLS) and transmission electron microscopy (TEM) were compared. With the developed method a comprehensive understanding in terms of dissolved Ag and Ag-NP concentration as well as an element selective, mass- and number particle size distribution (PSD) was obtained. In relation to batch-DLS, the reliability of the data was improved significantly. In comparison to TEM, faster measurement times and the ability to determine the samples directly in dispersions are clearly advantageous. The proposed setup shows potential for a rapid- and reliable characterization method of virtually any polydisperse metallic NP dispersion, many of them available on the market already.

Spatial- and Time-Correlated Detection of Fission Fragments

With the goal to measure angular correlations of fission fragments in rare fission decay (e.g. ternary and quaternary fission), a multi-detector coincidence system based on two and up to four position sensitive pixel detectors Timepix has been built. In addition to the high granularity, wide dynamic range and per pixel signal threshold, these devices are equipped with per pixel energy and time sensitivity providing more information (position, energy, time), enhances particle-type identification and selectivity of event-by-event detection. Operation of the device with the integrated USB 2.0 based readout interface FITPix and the control and data acquisition software tool Pixelman enables online visualization and flexible/adjustable operation for a different type of experiments. Spatially correlated fission fragments can be thus registered in coincidence. Similarly triggered measurements are performed using an integrated spectrometric module with analogue signal chain electronics. The current status of development together with demonstration of the technique with a 252 Cf source is presented. 1 Motivation

Are contrast media required for (68)Ga-DOTATOC PET/CT in patients with neuroendocrine tumours of the abdomen?

To determine the value of intravenous contrast medium in (68)Ga-DOTA-Phe(1)-Tyr(3)-octreotide - (68)Ga-DOTATOC - PET/CT for the detection of abdominal neuroendocrine tumours (NET). In fifty-five patients with known or suspected NETs of the abdomen PET/CT was performed on a 64-row multi-detector hybrid system. For PET, 150 MBq of (68)Ga-DOTATOC were injected intravenously. Full-dose unenhanced, and arterial- and venous-phase contrast-enhanced CT images were obtained. Unenhanced and contrast-enhanced PET/CT images were evaluated separately for the presence of NETs on a per-region basis, by two separate teams with different experience levels. On unenhanced PET/CT, sensitivity and specificity ranged from 89.3% (junior team) to 92% (senior team), and 99.1% (junior team) to 99.2% (senior team), respectively. On contrast-enhanced PET/CT, sensitivity and specificity ranged from 92.3% (junior team) to 98.5% (senior team), and 99.4% (junior team) to 99.5% (senior team), respectively. These increases in sensitivity and specificity, due to the use of contrast-enhanced images, were statistically significant (P < 0.05). Intravenous contrast medium only moderately, aleit significantly, improves the sensitivity of (68)Ga-DOTATOC PET/CT for the detection of abdominal NETs, and hardly affects specificity. Thus, while contrast enhancement is justified to achieve maximum sensitivity, unenhanced images may be sufficient for routine PET/CT in NET patients. Contrast media moderately improve the sensitivity of (68)Ga-DOTATOC PET/CT for neuroendocrine tumours. Contrast media hardly affect the specificity of (68)Ga-DOTATOC PET/CT for neuroendocrine tumours. Unenhanced PET/CT is sufficient for routine imaging of patients with neuroendocrine tumours.

Special nuclear material detection with a mobile multi-detector system

The detection of special nuclear material has been studied with a mobile inspection system used both as a high sensitivity passive neutron/gamma spectroscopic tool and as an active inspection device using tagged neutrons. The detection of plutonium samples seems to be possible with passive interrogation, even for small samples, thanks to the yield of gamma ray and neutrons. Moreover the gamma ray spectrum shows clear signatures related to 239Pu. The passive detection of uranium is much more difficult because of the low neutron yield and of the easiness of shielding the gamma ray yield of highly enriched U samples. However, we show that active interrogation with tagged neutrons is able to provide signatures for the discrimination of uranium against other heavy metals.

Analysis of branched polymers by high resolution multidetector size exclusion chromatography: Separation of the effects of branching and molecular weight distribution

AbstractThis article presents the SEC analysis of branched polyisobutylene PIB and polystyrene PS with high molecular weight and broad multimodal molecular weight distribution. Both polymers were synthesized using an inimer technique, which results in long‐chain branched polymers with statistical branching and broad multimodal distributions. Using high resolution multidetector Size Exclusion Chromatography SEC the polymers were analyzed based on three branching factors: g = (Rz,br/Rz,lin)Mw; h = (〈Rh〉z,br/〈Rh〉z,lin)Mw ; and ρ = (R 1/2/〈Rh〉z). It is generally accepted that for monodisperse branched polymers g and h &lt; 1. In the case of our polydisperse PIB and PS, it was seen that g and h &gt; 1, and ρ increases with molar mass and the number of chain ends as predicted earlier. The multidetector SEC system allowed for the separation of branching and polydispersity, reported here for the first time experimentally. The g parameter as a function of DPi was compared to the theory developed by Zimm and Stockmayer. The plots followed a similar trend, but were shifted by a factor related to the average chain length between branching points. The ρ parameter decreased with increasing DPi, as predicted theoretically by Kajiwara. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Tests of the MICE Electron Muon Ranger frontend electronics with a small scale prototype

The MICE experiment is being commissioned at RAL to demonstrate the feasibility of the muon ionization cooling technique for future applications such as the Neutrino Factory and the Muon Collider. The cooling will be evaluated by measuring the emittance before and after the cooling channel with two 4 T spectrometers; to distinguish muons from the background, a multi-detector particle identification system is foreseen: three Time of Flight stations, two Cherenkov counters and a calorimetric system consisting of a pre-shower layer and a fully active scintillator detector (EMR) are used to discriminate muons from pions and electrons. EMR consists of 48 planes of triangular scintillating bars coupled to WLS fibers readout by single PMTs on one side and MAPMTs on the other; each plane sensible area is 1 m 2. This article deals with a small scale prototype of the EMR detector which has been used to test the MAPMT frontend electronics based on the MAROC ASIC; the tests with cosmic rays using both an analog mode and a digital readout mode are presented. A very preliminary study on the cross talk problem is also shown.