Scanning Room Research Articles

Optimization of MRI Turnaround Times Through the Use of Dockable Tables and Innovative Architectural Design Strategies.

The purpose of this study is to increase the value of MRI by reengineering the MRI workflow at a new imaging center to shorten the interval (i.e., turnaround time) between each patient examination by at least 5 minutes. The elements of the MRI workflow that were optimized included the use of dockable tables, the location of patient preparation rooms, the number of doors per scanning room, and the storage location and duplication of coils. Turnaround times at the new center and at two existing centers were measured both for all patients and for situations when the next patient was ready to be brought into the scanner room after the previous patient's examination was completed. Workflow optimizations included the use of dockable tables, dedicated patient preparation rooms, two doors in each MRI room, positioning the scanner to provide the most direct path to the scanner, and coil storage in the preparation rooms, with duplication of the most frequently used coils. At the new imaging center, the median and mean (± SD) turnaround times for situations in which patients were ready for scanning were 115 seconds (95% CI, 113-117 seconds) and 132 ± 72 seconds (95% CI, 129-135 seconds), respectively, and the median and mean turnaround times for all situations were 141 seconds (95% CI, 137-146 seconds) and 272 ± 270 seconds (95% CI, 263-282 seconds), respectively. For existing imaging centers, the median and mean turnaround times for situations in which patients were ready for scanning were 430 seconds (95% CI, 424-434 seconds) and 460 ± 156 seconds (95% CI, 455-465 seconds), respectively, and the median and mean turnaround times for all situations were 481 seconds (95% CI, 474-486 seconds) and 537 ± 219 seconds (95% CI, 532-543 seconds), respectively. The optimized MRI workflow resulted in a mean time savings of 5 minutes 28 seconds per patient.

Roles of contrast-enhanced ultrasound and diffusion-weighted magnetic resonance imaging and their comparison in solid space-occupying lesions of the liver – Microbubbles and micromovements in imaging

Aims: This study aims to establish the role of contrast-enhanced ultrasound (CEUS) and diffusion-weighted (DW) magnetic resonance imaging (MRI) in the characterization of solid liver lesions. Settings and Design: An analysis of 22 patients undergoing CEUS and DW MRI following identification of 1 or more solid liver lesions on conventional ultrasonography. Subjects and Methods: The study is carried in a standard Doppler ultrasound machine with contrast ultrasound capabilities and 1.5T MRI machine over a period of 2 years from July 2015 to June 2017. After baseline US examination, a bolus of 1.0–2.4 ml of ultrasound contrast agent was administered intravenously followed by 10 ml of saline flush. CEUS images were obtained during arterial, portal venous, and delayed phases. After CEUS, patient is transferred to MRI scanning room where the DW imaging (DWI) sequence is taken. The CEUS and DW MRI diagnosis were compared to other imaging modalities, histopathology, and/or clinical follow-up after 12 months. Statistical Analysis Used: Sensitivity, specificity, positive predictive value, negative predictive value, accuracy rate and receiver operating characteristic analysis curve was performed using Statistical Package – SPSS ver. 17.0. Statistical evaluation of qualitative analysis between benign and malignant lesions was performed using the Fisher's exact test. Results: CEUS correctly identified malignant liver lesions in 13 out of 14 cases, with the final diagnosis confirmed by histopathology in 6 cases, by other imaging modalities in 7 cases and follow-up in 1 case. Eight patients were correctly identified as benign liver lesions on CEUS imaging, with all these cases confirmed on other imaging modalities and/or follow-up and two cases by histopathology. In the detection of malignancy, the sensitivity is 86.7% and specificity is 100%. On the DW images the Mean apparent diffusion coefficient (ADC) value for benign lesions is 1.5 and mean ADC value for malignant lesions is 0.7. The ADC was significantly higher in benign lesions than in malignant lesions (P < 0.01). Conclusions: In our experience, CEUS and DWI with ADC values are highly accurate in confirming benign lesions, early detection of malignant lesions, and metastases in known primary malignancy patients. Other advantage of CEUS and DW MRI is that it is also cost-effective as compared to simultaneously performing individual investigations and can be performed in renal insufficiency patients. Hence, we conclude that CEUS and DW MRI sequence should be used in routine practice.

Do heat and moisture exchangers in the anaesthesia breathing circuit preserve body temperature in dogs undergoing anaesthesia for magnetic resonance imaging?

ObjectiveTo investigate whether the use of a heat and moisture exchanger (HME) preserves body temperature in dogs weighing <10 kg anaesthetised for magnetic resonance imaging (MRI). Study designProspective, randomised, clinical trial. AnimalsThirty-one client-owned dogs. MethodsDogs were assigned randomly to a treatment group [HME (n = 16) or no HME (n = 15)]. Dogs were pseudorandomised according to the premedication they were administered, either dexmedetomidine or no dexmedetomidine. Induction agents were not standardised. General anaesthesia was maintained with isoflurane vaporised in 100% oxygen delivered using a T-piece and a fresh gas flow of 600 mL kg−1 minute−1. Rectal temperature was measured before premedication (T1), after induction (T2), before moving to the MRI unit (T3) and at the end of the MRI scan (T4). Ambient temperatures were measured in the induction room, outside and inside the MRI unit. Data were analysed using a general linear model with T4 as the outcome variable. Linear correlations were performed between T1, T2, T3 and T4, and variables that predicted T4 were investigated. ResultsSex, age and body mass were not significantly different between groups. There were no significant differences in rectal temperature between groups at any time point (group with HME at the end of MRI = 36.3 ± 1.1 °C; group with no HME at the end of MRI = 36.2 ± 1.4 °C) but at the end of the MRI, dogs administered dexmedetomidine (36.6 ± 0.7 °C) had a higher rectal temperature compared with dogs not administered dexmedetomidine (35.9 ± 1.6 °C) for premedication. Rectal temperature varied directly with ambient temperature in MRI scanning room and inversely with anaesthetic duration. Conclusions and clinical relevanceUsing an HME did not alter body temperature in dogs weighing <10 kg undergoing an MRI, but including dexmedetomidine in the premedication regimen seemed to preserve the body temperature during anaesthesia.

Measurement of radiation doses to occupational workers in nuclear medicine

Aims: The study aimed at measuring the external radiation doses to workers from patients who were administered radiopharmaceuticals in the nuclear medicine department. The purpose of this study was to evaluate the radiation safety procedures in the department of nuclear medicine. Methods: A total of 80 patients were randomly selected for the study. These patients were injected with either 99mTcpertechnetate or 99mTc-MDP (methylene diphosphonate). The dose rate was measured in hot lab, waiting room and in the scanning room at distances of 10, 50 and 100 cm from the patient at different time intervals by using a radiation survey meter. The absorbed dose from radioactive patient to radiation workers was calculated by using RADAR software and mathematical formulae from the measured dose rate. Results: The mean dose rate from thyroid scan atients at a distance of 10, 50 and 100 cm, after administration of injection was found to be 41 μSv/h, 31 μSv/h and 22 μSv/h respectively; whereas the dose rate from bone scan patients was calculated at 62 μSv/h, 31 μSv/h and 28 μSv/h. The dose rate was also measured after 15 min and 30 min in waiting and scanning room for the same patients. The mean absorbed dose to nuclear medicine occupational workers calculated both manually and using RADAR software came out to be less than 1mSv/year. Conclusion: The external doses to radiation workers were within permissible level. The results obtained in the present study are comparable to the previous studies conducted world wide. The radiation dose level to occupational workers in our nuclear medicine department does not exceed the recommended dose limits for workers.

Neurophysiologic Changes in Resting State Connectivity Induced by Differing Qualities of Beef Stimuli

ObjectivesFunctional magnetic resonance imaging (fMRI) has unveiled how many foods and basic rewards are processed, but imaging has not been widely used to investigate stimulation of solid foods, like steak, due to safety and quality issues that can arise. Resting state fMRI scans allow for administration of a stimulus before scanning, and literature has shown resting state networks reflect functional connectivity between brain regions. Resting state scans show connected regions by evaluating downstream effects of neural connectivity that are correlated to other regions of interest. We believe that hedonic circuits will be activated while eating steak, similar to other rewards. The objective of this experiment was to evaluate functional connectivity after consuming different qualities of steak.Materials and MethodsResting state scans of trained participants (n = 8) were taken prior to, directly after, and an extended time (25 to 30 minutes) after receiving high or low quality steak samples. Participants were re-scanned on a separate day, when they were fed the other quality steak. Blood oxygen level dependant imaging displayed hemodynamic fluctuation through the brain during fMRI procedures. Initial images were taken in the scanner before consumption. Participants left the scanning room to eat their sample, and marked a 152.4 mm anchored visual analog scale (VAS) at any point along the line as a subjective evaluation of tenderness, juiciness, flavor, and overall liking. The VAS was anchored as terrible, very poor, poor, fair, good, very good, and excellent at 0, 25.4, 50.8, 76.2, 101.6, 127.0, and 152.4 mm, respectively. After re-entry scans were taken as soon as possible, then participants cleansed their palates in a separate room before a final resting state scan was taken. Analysis of fMRI data was conducted using fMRI Expert Analysis Tool. A priori analysis investigated connectivity to the right and left amygdala, as well as the right and left anterior insula. Analysis of VAS data was conducted using SAS (SAS Inst. Inc., Cary, NC).ResultsImaging data showed that high quality steak resulted in greater functional connectivity between the left and right anterior insula as well as the left and right amygdala to the striatum, medial orbitofrontal cortex, and insular cortex directly after consumption (P ≥ 0.05). There was also greater functional connectivity between the left and right anterior insula as well as the left and right amygdala to the striatum, orbitofrontal cortex, and hippocampus an extended time after consumption (P ≤ 0.05). High quality steak was perceived superior for each palatability trait, having mean VAS measurements of 140.46, 134.37, 142.75, and 139.19, for tenderness, juiciness, flavor, and overall liking, respectively. Low quality steak had mean VAS measurements of 49.28, 49.53, 49.02, and 52.58, for tenderness, juiciness, flavor, and overall liking, respectively (P ° 0.01).ConclusionThese results suggest that resting state fMRI may be useful for evaluating neural processes following sensory experience, paprticularly steak consumption. We observed variation in functional connectivity of steak, due to quality. This novel technique has potential to bring about new methods of sensory evaluation for meat products that incorporate use of neuroimaging. This research adds knowledge and understanding to many areas of study about neural responses to hedonic stimuli.

Improving Radiation Awareness and Feeling of Personal Security of Non-Radiological Medical Staff by Implementing a Traffic Light System in Computed Tomography.

Non-radiological medical professionals often need to remain in the scanning room during computed tomography (CT) examinations to supervise patients in critical condition. Independent of protective devices, their position significantly influences the radiation dose they receive. The purpose of this study was to assess if a traffic light system indicating areas of different radiation exposure improves non-radiological medical staff's radiation awareness and feeling of personal security. Phantom measurements were performed to define areas of different dose rates and colored stickers were applied on the floor according to a traffic light system: green = lowest, orange = intermediate, and red = highest possible radiation exposure. Non-radiological medical professionals with different years of working experience evaluated the system using a structured questionnaire. Kruskal-Wallis and Spearman's correlation test were applied for statistical analysis. Fifty-six subjects (30 physicians, 26 nursing staff) took part in this prospective study. Overall rating of the system was very good, and almost all professionals tried to stand in the green stickers during the scan. The system significantly increased radiation awareness and feeling of personal protection particularly in staff with ≤ 5 years of working experience (p < 0.05). The majority of non-radiological medical professionals stated that staying in the green stickers and patient care would be compatible. Knowledge of radiation protection was poor in all groups, especially among entry-level employees (p < 0.05). A traffic light system in the CT scanning room indicating areas with lowest, intermediate, and highest possible radiation exposure is much appreciated. It increases radiation awareness, improves the sense of personal radiation protection, and may support endeavors to lower occupational radiation exposure, although the best radiation protection always is to re-main outside the CT room during the scan. • A traffic light system indicating areas with different radiation exposure within the computed tomography scanner room is much appreciated by non-radiological medical staff. • The traffic light system increases non-radiological medical staff's radiation awareness and feeling of personal protection. • Knowledge on radiation protection was poor in non-radiological medical staff, especially in those with few working experience.

Gammeltoft, T. M. Haunting Images: A Cultural Account of Selective Reproduction in Vietnam. Berkeley, CA: University of California Press. 2014. ix + 315pp £24.95 (pbk) ISBN 978‐0‐520‐27843‐1

Gammeltoft, T. M. Haunting Images: A Cultural Account of Selective Reproduction in Vietnam. Berkeley, CA: University of California Press. 2014. ix + 315pp £24.95 (pbk) ISBN 978‐0‐520‐27843‐1

Low temperature decomposition of U(IV) and Th(IV) oxalates to nanograined oxide powders

Oxalate precipitation is a powerful technique for actinide oxide preparation at either laboratory or industrial scales. In this study we focus on the low temperature decomposition of Th(C2O4)2⋅2H2O and (N2H5)2U2(C2O4)5⋅nH2O into nanograined ThO2 and UO2 powders, which will be used later as precursors for the generation of materials emulating the nuclear fuel high burn up structure (HBS). The evolution with temperature of the nanoparticles properties has been investigated using several solid state analytical techniques (transmission and scanning electron microscopy, room and high temperature powder X-ray diffraction, Raman spectroscopy, thermogravimetry). Oxide powders with a high degree of crystallinity and grain size from ∼10nm were prepared. Their purity was examined with special focus on the presence of carbonates. It was found that carbonate content in the final powder did not exceed 3.4wt.%, for the powder treated at 600°C for 1h.

A MEMS based acetone sensor incorporating ZnO nanowires synthesized by wet oxidation of Zn film

In this work, we report a simple and efficient method for synthesis of ZnO nanowires by thermal oxidation of Zn film and their integration with MEMS technologies to fabricate a sensor for acetone vapour detection. ZnO nanowires were prepared by thermal oxidation of sputter deposited Zn film. The nanostructured ZnO was characterized by x-ray diffraction, a scanning electron microscope and room temperature photoluminescence measurements. The ZnO nanowires synthesis process was integrated with MEMS technologies to obtain a sensor for volatile organic compounds, incorporating an on-chip Ni microheater and an interdigited electrode structure. To reduce the heat loss from the on-chip microheater, the sensor was made on a thin silicon diaphragm obtained via a modified reactive ion etching process. This resulted in considerable power saving during sensor operation. For this, a three-mask process was used. The performance of the microheater was simulated on COMSOL and validated experimentally. The sensor has been tested for acetone vapour sensing and the operating parameters were optimized. The sensor has the ability to detect acetone vapour at 5 parts per million (ppm) concentrations when operated at 100 °C. The sensor consumed only 36 mW power and showed a high-sensitivity value of 26.3% for 100 ppm of acetone vapour.

SU-C-144-03: Validation of Ceiling Shielding in CT/PET Room with RADEYE

Purpose: The purpose of this study was two-fold: (a) to measure the magnitude of scattered radiation levels in CT/PET room; and (b) to evaluate the effectiveness of shielding of the ceiling of a PET/CT suite. Methods: Six RadEye detectors were placed in the CT/PET room, four in the ceiling, and two at one meter above floor. A RadEye detector recorded data every 25 seconds throughout the day. The detector was turned on at the beginning of the day and the doses were transferred to a laptop for analysis at the end of the day. The dose to a non-radiation worker above the CT/PET room was estimated based on the ceiling data. The dose build up factor was used in the dose estimate. The magnitude of transmitted CT radiation in the room above was measured separately with RadEye. Results: The CT component of the scattered radiations showed approximately cone beam shape of the iso-dose curve. The CT dose contributed about 80% of the total dose while the PET contributed 20% within the scanning room. The combined dose to a person upstairs sitting in a chair at 0.5 meter high above the PET/CT suite was 4×10−6 mSv per week. In addition, the physical measurement at the interstitial space above the ceiling recorded only 0.12 mR per day, which was the background dose. Conclusion: This study has quantified the CT and PET doses contributions separately in the clinical CT/PET room. An analytical model was developed to calculate the non-occupational personnel dose above the CT/PET room and the calculated results were confirmed by physical measurements. The actual physical dose was 50 times smaller than the NCRP design goals of 0.02 mSv/wk.

Bifunctional Gd2O3:Er3+ particles with enhanced visible upconversion luminescence

This study examined the enhanced upconversion luminescence emission of bimodal Gd2O3:Er3+ particles by codoping with a trace amount of Li+ ions. Gd2O3:Er3+/Li3+ composite particles with enhanced upconversion luminescence emission were synthesized by using a simple urea homogeneous precipitation method. The effect of the particle size and Er3+/Li+ concentration ratio on the structural, morphological and optical properties of Gd2O3:Er3+/Li+ particles were studied systematically by X-ray powder diffraction, field emission scanning electron microscopy and room temperature photoluminescence. Strong upconversion eye-visible green light emission was observed from the Gd2O3:Er3+/Li+ particles under continuous near-infrared pump excitation from a commercially available diode laser. Monodisperse bimodal Gd2O3:Er3+/Li+ particles show a good potential for biomedical and solid state lighting applications.

Fabrication and characterization of ZnO nanostructures on Si(111) substrate using a thin AlN buffer layer

In the present work, radio-frequency (RF) nitrogen plasma-assisted molecular beam epitaxy (PA-MBE) technique was used to grow AlN thin layers on Si(111) substrate. Subsequently, the thermal evaporation technique was used to deposit the zinc films on Si(111) substrates with AlN as buffer layer. ZnO nanostructures were obtained from zinc granulated (99.99%) by thermal oxidation from 400 °C to 600 °C in air for 1 hours without any catalysts. The effect of annealing temperatures were studied ranging from 400 °C to 600 °C in air for 1 hours. The AlN was introduced to accommodate the lattice mismatch and thermal expansion mismatch between ZnO layer and Si substrate. The structural and optical properties of ZnO nanostructures are studied through scanning electron microscopy (SEM), X-ray diffraction (XRD) and room temperature photoluminescence (PL) spectroscopy. The films show a polycrystalline hexagonal wurtzite structure without preferred (0002) orientation. The mean grain sizes are calculated to be about 18 nm, 22 nm and 50 nm for the ZnO films prepared at temperatures of 400 °C, 500 °C and 600 °C. The structure of the fabricated nanomaterials were characterized by scanning electron microscopy (SEM). The PL spectra of the ZnO nanostructures having a sharp excitonic ultraviolet (UV) emission and very weak defect-related deep level visible emissions. It is showed that the ZnO nanostructures thermal annealed treatment was performed at 600 °C shows the strongest UV emission intensity among the temperatures ranges studied. In addition, from the one-dimensional ZnO nanostructures thermal annealed at 600 °C, the stronger UV emission is assigned to the best crystalline quality of the ZnO film

Propofol Drip Infusion Anesthesia for MRI Scanning: Two Case Reports

The magnetic resonance imaging (MRI) room is a special environment. The required intense magnetic fields create unique problems with the use of standard anesthesia machines, syringe pumps, and physiologic monitors. We have recently experienced 2 oral maxillofacial surgery cases requiring MRI: a 15-year-old boy with developmental disability and a healthy 5-year-old boy. The patients required complete immobilization during the scanning for obtaining high-quality images for the best diagnosis. Anesthesia was started in the MRI scanning room. An endotracheal intubation was performed after induction with intravenous administration of muscle relaxant. Total intravenous anesthesia via propofol drip infusion (4-7 mg/kg/h) was used during the scanning. Standard physiologic monitors were used during scan pauses, but special monitors were used during scanning. In MRI scanning for oral maxillofacial surgery, general anesthesia, with the added advantage of having a secured airway, is recommended as a safe alternative to sedation especially in cases of patients with disability and precooperative chidren.

The Impact of Tandem-and-Ovoids Displacements on High-dose-rate (HDR) Plans

A Comparison of Outcomes Between Concurrent Chemoradiation Therapy and Radiation Therapy Alone in Cancer of the Uterine Cervix: A Single Institutional Experience J. Kim, S. Byun, O. Kim, S. Park, E. Choi, Y. Oh, and C. Cho; Department of Radiation Oncology, Keimyung University, School of Medicine, Dongsan Medical Center, Daegu, Korea, Republic of Korea, Department of Obstetrics and Gynecology, Keimyung University, School of Medicine, Dongsan Medical Center, Daegu, Korea, Republic of Korea

Standardized assessment of new electromagnetic field generators in an interventional radiology setting

Two of the main challenges associated with electromagnetic (EM) tracking in computer-assisted interventions (CAIs) are (1) the compensation of systematic distance errors arising from the influence of metal near the field generator (FG) or the tracked sensor and (2) the optimized setup of the FG to maximize tracking accuracy in the area of interest. Recently, two new FGs addressing these issues were proposed for the well-established Aurora(®) tracking system [Northern Digital, Inc. (NDI), Waterloo, Canada]: the Tabletop 50-70 FG, a planar transmitter with a built-in shield that compensates for metal distortions emanating from treatment tables, and the prototypical Compact FG 7-10, a mobile generator designed to be attached to mobile imaging devices. The purpose of this paper was to assess the accuracy and precision of these new FGs in an interventional radiology setting. A standardized assessment protocol, which uses a precisely machined base plate to measure relative error in position and orientation, was applied to the two new FGs as well as to the well-established standard Aurora(®) Planar FG. The experiments were performed in two different settings: a reference laboratory environment and a computed tomography (CT) scanning room. In each setting, the protocol was applied to three different poses of the measurement plate within the tracking volume of the three FGs. The two new FGs provided higher precision and accuracy within their respective measurement volumes as well as higher robustness with respect to the CT scanner compared to the established FG. Considering all possible 5 cm distances on the grid, the error of the Planar FG was increased by a factor of 5.94 in the clinical environment (4.4 mm) in comparison to the error in the laboratory environment (0.8 mm). In contrast, the mean values for the two new FGs were all below 1 mm with an increase in the error by factors of only 2.94 (Reference: 0.3 mm; CT: 0.9 mm) and 1.04 (both: 0.5 mm) in the case of the Tabletop FG and the Compact FG, respectively. Due to their high accuracy and robustness, the Tabletop FG and the Compact FG could eliminate the need for compensation of EM field distortions in certain CT-guided interventions.

Early computed tomography scanning in multisystem trauma: The evidence

The utility of computed tomography as a radiological investigation following multisystem trauma is already well established in current practice. This article examines the existing evidence and rationale behind the use of early computed tomography scanning in the management of the multisystem trauma patient, with a particular emphasis on the use of ‘whole body’ computed tomography scanning as a component of their initial management in the Emergency Department. The use of computed tomography has been shown to be superior to plain radiography for the detection of injuries in important body regions including the spine, thorax, abdomen and pelvis. Computed tomography scan of the head and cervical spine is also well established as the first investigation of choice for significant traumatic brain injury. The potential benefits of whole body computed tomography include reduced time to diagnosis and intervention, as well as significant improvements in clinical outcome and survival. Concerns regarding a whole body computed tomography approach relate to the increased ionising radiation dosage that patients will be exposed to, and perceived risks of the secondary transfer and scanning room environment itself. Potential barriers to the use of whole body computed tomography are also explored and discussed. This article also presents a proposed clinical algorithm derived from the results of a recent Delphi study into whole body computed tomography following blunt multitrauma, along with conclusions and recommendations from the subject matter panel review process.

Recoilless Fraction in Amorphous and Nanocrystalline FeCuNbSiB System

ABSTRACTDifferential scanning calorimetry, X-ray diffraction, and room temperature Mössbauer spectrum measurements of Fe73.5Cu1Nb3Si13.5B9 (Finemet) alloy have been carried out in order to study its structural and magnetic properties as a function of annealing temperature. The Mössbauer spectra of annealed Finemet alloy could be fitted with 4 or 5 sextets and one doublet at higher annealing temperatures, revealing the appearance of different crystalline phases corresponding to the different Fe sites above the crystallization temperature. The appearance of the nanocrystalline phases at different annealing temperatures was further confirmed by the recoilless fraction measurements. These made use of our recently-developed dual absorber method, which made it possible to determine precisely the recoilless fractions of the amorphous, nanocrystalline and grain boundary phases separately.

Partnering with Engineers to Identify and Empirically Evaluate Delays in Magnetic Resonance Imaging: Laying the Foundations for Quality Improvement and System-based Practice in Radiology

The aim of this study was to evaluate the feasibility of partnering with engineering students and critically examining the merit of the problem identification and analyses students generated in identifying sources impeding effective turnaround in a large university department of diagnostic radiology. Turnaround involves the time and activities beginning when a patient enters the magnetic resonance scanner room until the patient leaves, minus the time the scanner is conducting the protocol. A prospective observational study was conducted, in which four senior undergraduate industrial and operations engineering students interviewed magnetic resonance staff members and observed all shifts. On the basis of 150 hours of observation, the engineering students identified 11 process steps (eg, changing coils). They charted machine use for all shifts, providing a breakdown of turnaround time between appropriate process and non-value-added time. To evaluate the processes occurring in the scanning room, the students used a work-sampling schedule in which a beeper sounded 2.5 times per hour, signaling the technologist to identify which of 11 process steps was occurring. This generated 2147 random observations over a 3-week period. The breakdown of machine use over 105 individual studies showed that non-value-added time accounted for 62% of turnaround time. Analysis of 2147 random samples of work showed that scanners were empty and waiting for patients 15% of the total time. Analyses showed that poor communication delayed the arrival of patients and that no one had responsibility for communicating when scanning was done. Engineering students used rigorous study design and sampling methods to conduct interviews and observations. This led to data-driven definition of problems and potential solutions to guide systems-based improvement.

Nylon 6/TiO2 Composites by in situ Anionic Ring-Opening Polymerization of ϵ-Caprolactam: Synthesis, Characterization, and Properties

Two series of nylon 6/TiO2 composites were obtained via anionic ring opening polymerization of ϵ-caprolactam in the presence of untreated and surface-treated TiO2 with 3-aminopropyltriethoxysilane (APTEOS) as coupling agent by the rotational molding technique. The polymerization process was carried out using a system initiator/activator based on sodium dicaprolactamato-bis(2-methoxyethoxo)aluminate and N,N′-[methylene-di(4,4′-phenylene)bis-carbamoyl]bis-ϵ-caprolactam. All tests were performed at the initial polymerization temperature of 160° ± 2°C. The influence of both untreated and treated TiO2 particle concentration on the degree of conversion (DC), intrinsic viscosity [η], weight-average molecular weight , and water absorption of pure nylon 6 and its composite materials was investigated in the range of 0.0 to 8.0 wt.% TiO2. The thermal behavior and crystalline structures of pure nylon 6 and its composites have been studied in correlation with filler concentration by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and room temperature wide-angle X-ray diffraction (WAXD). The mechanical characteristics, including tensile and flexural properties, elongation at break, and notched Izod impact strength, of nylon 6 and its composites as a function of TiO2 filler content were investigated for all samples. Experimental results revealed that the unmodified and surface-modified TiO2 as fillers had distinct influence on the degree of conversion, weight-average molecular weight, crystallization behavior, thermal stability, mechanical properties, and water absorption of nylon 6 matrix.

Synthesis of CoFe2O4 powder via PVA assisted sol–gel process

CoFe2O4 ferrites were synthesized by sol–gel method, having metal nitrates as precursors and PVA as surfactant, followed by a heat treatment at 960 °C for 2 h. The ultrafine ferrite powders obtained have been characterized by X-ray diffraction, thermal gravimetry, differential scanning calorimetry and room temperature magnetic measurement studies. The morphology of the powder was identified by high resolution-scanning electron microscopy. X-ray diffraction results indicate that the resultant CoFe2O4 crystallites consist of spinel phase. Significant differences in magnetic properties of CoFe2O4 samples synthesized with various concentrations of PVA were observed. The magnetisation measurements show that when the PVA concentration increased, coercivity initially decreased and then increased where as retentivity and magnetisation decreased. The optimum concentration of PVA for the synthesis of CoFe2O4 ferrites is obtained from this investigation. Obviously this material can be used as an efficient candidate for practical recording purpose.