A Monte Carlo simulation study of the impact of novel scintillation crystals on performance characteristics of PET scanners

© 2018 Associazione Italiana di Fisica Medica Objective: The purpose of this study is to validate a Monte Carlo simulation model for the clinical Siemens Biograph mCT PET scanner using the GATE simulation toolkit, and to evaluate the performance of six different scintillation materials in this model using the National Electrical Manufactures Association (NEMA) NU 2-2007 protocol. Methods: A model of the Biograph mCT PET detection system and its geometry was developed. NEMA NU 2-2007 phantoms were also modelled. The accuracy of the developed scanner model was validated through a comparison of the simulation results from GATE, SimSET and PeneloPET toolkits, and experimental data obtained using the NEMA NU 2-2007 protocols. The evaluated performance metrics included count rate performance, spatial resolution, sensitivity, and scatter fraction (SF). Thereafter, the mCT PET scanner was simulated with six different candidate high-performance scintillation materials, including LSO, LaBr3, CeBr3, LuAP, GLuGAG and LFS-3, and its performance evaluated according to the NEMA NU 2-2007 specifications. Results: The Monte Carlo simulation model demonstrates good agreement with the experimental data and results from other simulation packages. For instance, the scatter fraction calculated using GATE simulation is 34.35% while the experimentally measured value is 33.2%, 38.48% for the SimSET, and 34.8% for the PeneloPET toolkit. The best-performing scintillation materials were found to be LuAP, LSO and LFS-3, while GLuGAG offers acceptable performance if cost is the dominant concern. Conclusion: The main performance characteristics of the Biograph mCT PET scanner can be simulated accurately using GATE with a good agreement with other Monte Carlo simulation packages and experimental measurements. Newly developed scintillators show promise and offer alternative options for the design of novel generation PET scanners

Missile Guidance Law Design via Backstepping Technique

In this paper a Back-stepping Control technique is proposed for command to line-of-sight missile guidance law design. In this design, the three-dimensional (3-D) CLOS guidance problem is formulated as a tracking problem of a time-varying nonlinear system. Simulation results for different engagement scenarios illustrate the validity of the proposed Backstepping-based Guidance Law

Organically modified nanoclay filled thin-film nanocomposite membranes for reverse osmosis application

This study validates, for the first time, the effectiveness of two nanoclays, that is, cloisite (CS)-15A and montmorillonite (MNT) at the polyamide (PA) active layer in the reverse osmosis (RO) membrane. Cloisite-15A is natural montmorillonite modified with dimethyl dihydrogenated tallow quaternary ammonium salt. Thin-film composite (TFC) membranes were fabricated by the interfacial polymerization (IP) process between the trimesoylchloride (TMC)–n-hexane solution and m-phenylenediamine (MPD)–aqueous solution; the IP process took place on a polysulfone support sheet. The two types of nanoparticles were added in various weight ratios (0.005 wt.%–0.04 wt.%) in the n-hexane solution of TMC. Different characterizations like X-ray diffraction (XRD), contact angle, transmission electron microscopy (TEM), and membrane performance tests were performed to analyse the membrane properties. Both XRD and TEM studies proved that the two nanoclays are successfully anchored at the different sites of the PA layer. CS-15A could accelerate the water flux from 15 to 18.65 L/m2·h with NaCl rejection enhancement from 72% to 80%, relative to the control membrane. Conversely, MNT also enhanced the flux from 15 to 40 L/m2·h, but NaCl rejection reduced from 70% to 23%. The mechanism of water uptake in nanoclays was also discussed. The results pave the way for a complete future study, in which these phenomena should be studied in great detail.This research was funded by Qatar University, grant number IRCC-2019-004.The authors would like to acknowledge the support of Qatar University through project number IRCC-2019-004. Also, the authors acknowledge the assistance granted by KACST through the National Science, Technology, and Innovation Plan (NSTIP) unit of King Fahd University of Petroleum and Minerals (KFUPM) through NSTIP research grant number 08WAT-80-4. The assistance in membrane preparation by Matsuura group, Ottawa University, Canada and Rasel Das, Kyushu University Japan for discussion on the results are highly appreciated.Scopu

Cancer Patterns in Karachi Division (1998-1999)

Objective: A minimal cancer incidence data for Karachi, the largest city of Pakistan, is being presented here, for the years 1998-1999. The city has a population of 9,802,134; males 5,261,712 (52.6%) and females 4,540,422 (47.4%); census 19981. Methodology: A predominantly mixed (passive and active) registration system has evolved in Karachi, the data sources being the hospitals within the Karachi Division. The reported/retrieved cancer data sets at the Karachi Cancer Registry are checked, coded, computerised in an analytical format and analysed. Results: The incident cancer cases registered in Karachi, during the 2-year period, 1st January 1998 to 31st December 1999 were analysed. The age-standardised incidence rate (ASR) of cancer, all sites was 132.4/100,000 for the males. Cancer of the lung 10.8%; ASR 17.3 was the most frequently recorded malignancy, followed by oral cavity 10.5%; ASR 13.2 and larynx 5.0%; ASR 7.4. The age-standardised incidence rate (ASR) of cancer, all sites was 133.0/100,000 in the females. Cancer of the breast, 32.0%; ASR 40.7 was the most frequently recorded malignancy, followed by oral cavity 8.1%; ASR 11.7 and gall bladder 3.6%; ASR 5.5. Conclusion: The present data has been calculated with an estimated 15-20% probable under ascertainment. Tobacco-associated cancers in Karachi were responsible for 38.3% of the tumours diagnosed amongst the males. Two principal cancers, breast and oral cavity were responsible for 40.1% of the cancers in females. A rare finding was the high incidence of gall bladder cancer in the females. At present it is difficult to determine whether this indicates a genuine high risk or a selection bias. A continuous process of cancer registration to study the trends in the incidence and an adequate cancer control program are possible and essential for Pakistan and can be based on the pattern being practiced in Karachi

Pneumatosis Intestinalis in COVID-19: Case Series.

OBJECTIVE:To describe the clinical characteristics and outcomes of patients with coronavirus disease 2019 (COVID-19) who developed pneumatosis intestinalis (PI). METHODS:This case series was conducted in intensive care units at two large tertiary care centers within the Northwell Health System, located in New York State. Patients were included if they were identified as having confirmed COVID-19 as well as pneumatosis intestinalis from March 16, 2020 to July 31, 2020. Patient demographics, clinical characteristics, vasopressor use, anticoagulation use, opiate use, paralytic use, COVID-19 treatment regimen, serum lactate, arterial pH, serum bicarbonate, subsequent intervention, and outcomes during hospitalization were collected. Results: A total of nine patients were identified. Average serum lactate was 4.33 mmol/L at time of diagnosis. Portal venous gas (56%) and bowel dilation (56%) were common radiographic findings. Subsequent morbidity (increased vasopressor requirements - 67%, acute kidney injury - 67%, increased oxygen requirements - 44%) and mortality (78%) were high. PI occurred despite a majority of patients being on anticoagulation (78%). Interleukin-6 (IL-6) inhibitors were commonly administered (56%) prior to development of PI. CONCLUSION:Pneumatosis intestinalis in COVID-19 is clinically significant, with high morbidity and mortality, and is also likely underdiagnosed

Hydatid cyst of ovary: an unusual site

Discovering a hydatid cyst in pelvic region, especially as primary localization, is a rare event; as a matter of fact according to data provided by literature the incidence is between 0.2 and 2.25%. The ovarian involvement is often secondary to a cyst's dissemination localized in a different site. When possible the optimal treatment is represented by radical laparotomic cystectomy. We report a case of an old postmenopausal woman presented with intermittent dull aching pain with 16 weeks cystic pelvic mass which mimicked the ovarian malignancy even after imaging techniques. We treated the case with laprotomic cystectom

A study of frequency and pulses for stepper motor controller system by using programmable logic controller

The stepper motor movement process produced different frequency and pulses. This research explained about the frequency and pulses for the stepper motor movement by using Programmable Logic Controller (PLC) as research method. The study was done to find the suitable frequency and pulses for stepper motor movement by developing a prototype stepper motor controller system. The pulse frequency used did not affected the distance of moving load in the stepper motor operations. The increasing number of pulse frequency only will affect the time taken for the stepper motor to complete its operations. The result showed that number of pulse frequency at high operation was 5000 Hz. Pulse number reacted as a manipulated variable that affected both factor which is time taken of stepper motor operation and the distance of moving load

Transition Metal Complexes of a-Naphthylamine Dithiocarbamate

a-Naphthylamine dithiocarbamate and its complexes with Co(II), Ni(U), Cu(II), Ru(III) , Rh(III), Pd(II), Pt(IV), Zn(II), Cd(II) and Hg(II) have been prepared and characterized by chemical analysis, IR - and reflectance spectral studies and magnetic susceptibili ty measurements. In all these complexes the dithiocarbamato moiety acts as a chelate. The Ni(II), Cu(II) and Pd(Il) complexes have been found to be square planar while those of Ru(III), Rh(III) and Pt(IV) were proposed to be octahedral in nature. The Co(II) ion seems to have a tetrahedral geometry, unlike the other known square planar dithiocarbamato complexes of Co(II). No definite structure, however, could be proposed for Zn(II), Cd(II) and Hg(II) on the basis of limited studies

Design of the Security Mechanism for a BPO Cloud Computing Platform

The security of a Cloud Computing Platform (CCP)is a key factor in its ability to operate successfully. Currently, the security issues of the physical resource layer and the user application layer of the cloud computing platform have been significantly studied in the field of information security and have already mature products and solutions. This research is aimed at the complex Business Process Outsourcing Cloud Computing Platform (BPO-CCP)for the banking and insurance industries. In particular we are concerned with the BPO-CCP`s virtualization security, cloud data security, access control, user authentication and authorization, and cloud computing auditing. This paper analyzes the specific needs of the platform's security. Then the Security Mechanism of the BPO Cloud Computing Platform (SM-BPO-CCP)is designed. During its implementation (around five years at the time of writing)this SM-BPO-CCP that we have designed has efficiently provided security protection for up to twenty BPO companies with each having more than 1000 employees. This SM-BPO-CCP linked to ten large banks and insurance companies, none of which experienced any security issues due to the protection offered by the SM-BPO-CCP

Why do families of sick newborns accept hospital care? a community-based cohort study in Karachi, Pakistan

Objective: Sick young infants are at high risk of mortality in developing countries, but families often decline hospital referral. Our objective was to identify the predictors of acceptance of referral for hospital care among families of severely ill newborns and infants Karachi, Pakistan. Study Design: A cohort of 541 newborns and infants referred from home by community health workers conducting household surveillance, and diagnosed with a serious illness at local community clinics between 1 January and 31 December 2007, was followed-up within 1 month of referral to the public hospital. Result: Only 24% of families accepted hospital referral. Major reasons for refusal were financial difficulties (67%) and father/elder denying permission (65%). Religious/cultural beliefs were cited by 20% of families. Referral acceptance was higher with recognition of severity of the illness by mother (odds ratio = 12.7, 95% confidence interval = 4.6 to 35.2), family\u27s ability to speak the dominant language at hospital (odds ratio = 2.0, 95% confidence interval = 1.3-3.1), presence of grunting in the infant (odds ratio = 3.3, 95% confidence interval = 1.2-9.0) and infant temperature Conclusion: Refusal of hospital referral for sick young infants is very common. Interventions that encourage appropriate care seeking, as well as community-based management of young infant illnesses when referral is not feasible are needed to improve neonatal survival in low-income countries