Digital Commons Network^™

A Silicon Strip Detector Dose Magnifying Glass For Imrt Dosimetry, J.H.D Wong, Martin Carolan, Michael Lerch, Marco Petasecca, Sutinder Khanna, V Perevertaylo, Peter Metcalfe, Anatoly Rosenfeld

Michael L.F. Lerch

Purpose: Intensity modulated radiation therapy (IMRT) allows the delivery of escalated radiation dose to tumor while sparing adjacent critical organs. In doing so, IMRT plans tend to incorporate steep dose gradients at interfaces between the target and the organs at risk. Current quality assurance (QA) verification tools such as 2D diode arrays, are limited by their spatial resolution and conventional films are nonreal time. In this article, the authors describe a novel silicon strip detector (CMRP DMG) of high spatial resolution (200 μm) suitable for measuring the high dose gradients in an IMRT delivery. Methods: A full characterization of the …

Comparison Of The New Moskin Detector And Fiber Optic Dosimetry System For Radiotherapy, Ian Kwan, Bong Soo Lee, Wook Jae Yoo, Donghyun Cho, Kyoungwon Jang, Sanghun Shin, Martin Carolan, Michael Lerch, V Perevertaylo, Anatoly Rosenfeld

Michael L.F. Lerch

In radiotherapy, interest in real-time dosimetry stems from the desire to monitor the dose delivered to the target volume and the surrounding normal tissue to enable clinicians to track the progress of the treatment, and prevent surrounding tissue from receiving too much radiation dose. In this study, the dosimetric performance of the new MOSkin dosimeter and a Bicron BCF-20 scintillating fiber was compared to depth dose measurements taken with a Farmer-type ionization chamber. The performance of the MOSkin and BCF-20 detectors in the build-up region of the depth dose curve, where the dose gradient is steep, is also compared to …

Evaluation Of A Thin Microstrip Detector For High Spatial Resolution Dosimetry, J Kalliopuska, Ashley Cullen, Michael Lerch, Marco Petasecca, M Santala, Anatoly Rosenfeld

Michael L.F. Lerch

VTT and Aalto University have supplied thin microstrip detector prototypes to CMRP for evaluation for the high spatial resolution dosimetry. The evaluation for dosimetry in microbeam radiation therapy (MRT) was done in a synchrotron microbeam at ESRF, France. Measurements studied a response of a single strip on the synchrotron microbeam in face-on and edge-on modes using CMRP designed and developed readout electronics for a parallel readout of single strips. Measurements were done in a passive mode without bias voltage and the detector was scanned through an array of intensive planar microbeams with the nominal width of 50 μm. The face-on …

Real-Time In Vivo Dosimetry With Mosfet Detectors In Serial Tomotherapy For Head And Neck Cancer Patients, Zhen-Yu Qi, Xiao-Wu Deng, Shao-Min Huang, Almon Shiu, Michael Lerch, Peter Metcalfe, Anatoly Rosenfeld, Tomas Kron

Michael L.F. Lerch

Purpose

A real-time dose verification method using a recently designed metal oxide semiconductor field effect transistor (MOSFET) dosimetry system was evaluated for quality assurance (QA) of intensity-modulated radiation therapy (IMRT).

Methods and Materials

Following the investigation of key parameters that might affect the accuracy of MOSFET measurements (i.e., source surface distance [SSD], field size, beam incident angles and radiation energy spectrum), the feasibility of this detector in IMRT dose verification was demonstrated by comparison with ion chamber measurements taken in an IMRT QA phantom. Real-time in vivo measurements were also performed with the MOSFET system during serial tomotherapy …

Evaluation Of Pixellated, Back-Sided Planar Photodetectors For High-Resolution Imaging Instrumentation, Mark Safavi-Naeini, Michael Lerch, Marco Petasecca, Giorgio Pignatel, Mark Reinhard, Anatoly Rosenfeld

Michael L.F. Lerch

Future generations of solid-state high-energy gamma imaging cameras require pixellated semiconductor photodetectors with the greatest possible detection efficiency. In this paper, a new type of planar silicon PIN photodiode is presented, in which both p+ and n+ electrodes are located on the same side of the device. The design offers highly efficient optical coupling between the backside and scintillator, providing a fill factor of close to 100%. The performance of this detector is modelled using the ISE-TCAD simulator and its electrical and spectroscopic characteristics are experimentally investigated for the case of direct interaction of ionising radiation and also with an …

Solid State Diode - Ionization Chamber Method For Measuring Out-Of-Field Neutron Dose In Proton Therapy, Amy Ziebell, B Clasie, Andrew Wroe, Reinhard Schulte, Mark Reinhard, Stephen Dowdell, Michael Lerch, Marco Petasecca, V Perevertaylo, Oleg Zinets, Igor Anokhin, Anatoly Rosenfeld

Michael L.F. Lerch

In proton therapy neutrons are introduced to out-of-field regions inside the patient. Clinicians would like to know the absorbed dose being deposited by neutrons separately to that from protons, so as to be able to directly apply their own dose equivalent weighting factors based on their opinion of the biological risk posed by neutrons in this region. The purpose of this study is to investigate a novel approach to experimentally separating the proton and neutron contributions to the absorbed dose in out-of-field regions. The method pairs specially designed silicon PIN diodes with a standard clinical ionization chamber. The sensitivity of …

In Vivo Verification Of Superficial Dose For Head And Neck Treatments Using Intensity-Modulated Techniques, Zhen-Yu Qi, Xiao-Wu Deng, Shao-Min Huang, Li Zhang, Zhi-Chun He, X. Allen Li, Ian Kwan, Michael Lerch, Dean Cutajar, Peter Metcalfe, Anatoly Rosenfeld

Michael L.F. Lerch

Skin dose is one of the key issues for clinical dosimetry in radiation therapy. Currently planning computer systems are unable to accurately predict dose in the buildup region, leaving ambiguity as to the dose levels actually received by the patient’s skin during radiotherapy. This is one of the prime reasons why in vivo measurements are necessary to estimate the dose in the buildup region. A newly developed metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector designed specifically for dose measurements in rapidly changing dose gradients was introduced for accurate in vivo skin dosimetry. The feasibility of this detector for skin dose measurements was verified in …

Verification Of The Plan Dosimetry For High Dose Rate Brachytherapy Using Metal-Oxide-Semiconductor Field Effect Transistor Detectors, Zhen-Yu Qi, Xiao-Wu Deng, Shao-Min Huang, Jie Lu, Michael Lerch, Dean Cutajar, Anatoly Rosenfeld

Michael L.F. Lerch

The feasibility of a recently designed metal–oxide–semiconductor field effect transistor (MOSFET) dosimetry system for dose verification of high dose rate (HDR) brachytherapy treatment planning was investigated. MOSFET detectors were calibrated with a 0.6 cm3 NE-2571 Farmer-type ionization chamber in water. Key characteristics of the MOSFET detectors, such as the energy dependence, that will affect phantom measurements with HDR 192Ir sources were measured. The MOSFET detector was then applied to verify the dosimetric accuracy of HDR brachytherapy treatments in a custom-made water phantom. Three MOSFET detectors were calibrated independently, with the calibration factors ranging from 0.187 to 0.215 cGy∕mV. A distance …

Monte Carlo Modelling Of A Silicon Strip Detector For Microbeam Radiation Therapy, Ashley Cullen, Michael Lerch, Marco Petasecca, Anatoly Rosenfeld

Michael L.F. Lerch

Microbeam radiation therapy is an experimental technique utilising synchrotron X-rays collimated into a planar array of microbeams. Due to the complex structure of the radiation field and high dose rate, this introduces dosimetric challenges. Current dosimetric methods are inadequate in that they lack either real-time readout, or high spatial resolution. A detector system, consisting of the Silicon Multi-Strip Detector and associated readout system was developed at the University of Wollongong. This system performs online, real-time dosimetry, and is designed for placement upstream of the patient as a transmission detector. The interaction of synchrotron radiation with this detector, both in terms …

Sugar As An Optimal Carbon Source For The Enhanced Performance Of Mgb2 Superconductors At High Magnetic Fields, Olga Shcherbakova, Alexey Pan, Jianli Wang, Andrey Shcherbakov, S. Dou, David Wexler, E Babic, M Jercinovic, O Husnjak

Jianli Wang

In this paper we report the results of an extended study of the effect of sugar doping on the structural and electromagnetic properties of MgB2 superconductors. High values of the upper critical field (Bc2) of 36 T and the irreversibility field (Birr) of 27 T have been estimated at the temperature of 5 K in a bulk MgB2 sample with the addition of 10 wt% of sugar. The critical current density (Jc(Ba)) of sugar-doped samples has been significantly improved in the high field region. The value of transport Jc has reached as high as 108 A m-2 at 10 T …

Micro-Patterned Surface Modification Of Poly(Dimethylsiloxane) (Pdms) Substrates For Tissue Engineering, Brad Winton, Mihail Ionescu, Chris Lukey, Mark Wilson, Ivan Nevirkovets, S. Dou

Mark R Wilson

Low energy metal ion implantation of poly(dimethylsiloxane) (PDMS) films simultaneously allows for the creation of complex and tuneable topographical features at the surface, while also enhancing the biocompatibility of the surface for biological applications. PDMS thick films were implanted with Mg, Ta, and Fe at constant dose. Cells cultured on all of the modified surfaces enjoyed an increase in viable cell count of over 440% when compared to the pristine surface, with the Fe implanted surface showing a 600% increase with a substantial increase in surface energy, which was reflected by the increased contact angle. This was achieved without any …

Flexible Free-Standing Graphene-Silicon Composite Film For Lithium-Ion Batteries, Jiazhao Wang, Chao Zhong, Shulei Chou, Hua Liu

Shulei Chou

Flexible, free-standing, paper-like, graphene-silicon composite materials have been synthesized by a simple, one-step, in-situ filtration method. The Si nanoparticles are highly encapsulated in a graphene nanosheet matrix. The electrochemical results show that graphene-Si composite film has much higher discharge capacity beyond 100 cycles (708 mAh g− 1) than that of the cell with pure graphene (304 mAh g− 1). The graphene functions as a flexible mechanical support for strain release, offering an efficient electrically conducting channel, while the nanosized silicon provides the high capacity.

Nanocrystalline Nio Hollow Spheres In Conjunction With Cmc For Lithium-Ion Batteries, Chao Zhong, Jiazhao Wang, Shulei Chou, Konstantin Konstantinov, Mokhlesur Rahman, Hua Liu

Shulei Chou

Hollow spherical NiO particles were prepared using the spray pyrolysis method with different concentrations of precursor. The electrochemical properties of the NiO electrodes, which contained a new type of binder, carboxymethyl cellulose (CMC), were examined for comparison with NiO electrodes with polyvinylidene fluoride (PVDF) binder. The electrochemical performance of NiO electrodes using CMC binder was significantly improved. For the cell made from 0.3 mol L−1 precursor, the irreversible capacity loss between the first discharge and charge is about 43 and 24% for the electrode with PVDF and CMC binder, respectively. The cell with NiO–CMC electrode has a much higher discharge …

Reducing Wave-Based Teleoperator Reflections For Unknown Environments, Laurence Bate, Christopher Cook, Zheng Li

Christopher Cook

Wave variables guarantee stability for delayed teleoperation. They also introduce reflections which can prove very disorientating for an operator. This paper presents a new method for reducing the wave reflections when operating in unknown environments. The new method does not only guarantee stability but also laboratory experiments show it also reduces wave reflections allowing for improved velocity tracking and force feedback in complex and unknown operating environments.

Treatment Of Coal Seam Gas Produced Water For Beneficial Use In Australia: A Review Of Best Practices, Long Nghiem, Ting Ren, Najdat Aziz, Ian Porter, Gyanendra Regmi

Long D Nghiem

There has been an exponential increase in both the production and exploration of coal seam gas (CSG) in Australia and many other regions in the world. A major issue associated with the production of CSG is the management of produced water. CSG is usually mixed with water in the coal seam, to recover the gas, the water must be first extracted from the coal seam to reduce pressure. This water — known as co-produced water or CSG water — is typically quite saline, large in volume and may contain heavy metals and other trace elements of concern. The management of …

Transmitter Diversity Antenna Selection Techniques For Wireless Channels Utilizing Differential Space-Time Block Codes, Jennifer Seberry, A. Mertins, Tadeusz Wysocki, Le Chung Tran

Dr Le Chung Tran

No abstract provided.

Linear Predictive Perceptual Filtering For Acoustic Vector Sensors: Exploiting Directional Recordings For High Quality Speech Enhancement, Muawiyath Shujau, Christian Ritz, Ian Burnett

Dr Muawiyath Shujau

This paper investigates the performance of a new technique for speech enhancement which combines Linear Predictive (LP) spectrum-based perceptual filtering to the recordings obtained from an Acoustic Vector Sensor (AVS). The technique takes advantage of the directional polar responses of the AVS to obtain a significantly more accurate representation of the LP spectrum of a target speech signal in the presence of noise when compared to single channel, omni-directional recordings. Comparisons between the speech quality obtained from the proposed technique and existing beamforming-based speech enhancement techniques for the AVS are made through Perceptual Evaluation of Speech Quality (PESQ) tests and …

Coupling Biophysical And Socioeconomic Models For Coral Reef Systems In Quintana Roo, Mexican Caribbean, Deborah Cleland, Jess Melbourne-Thomas, Craig Johnson, Pascal Perez, Jeremy Eustache, Elizabeth Fulton

Professor Pascal Perez

No abstract provided.

Verification Of The Plan Dosimetry For High Dose Rate Brachytherapy Using Metal-Oxide-Semiconductor Field Effect Transistor Detectors, Zhen-Yu Qi, Xiao-Wu Deng, Shao-Min Huang, Jie Lu, Michael Lerch, Dean Cutajar, Anatoly Rosenfeld

Dean Cutajar

The feasibility of a recently designed metal–oxide–semiconductor field effect transistor (MOSFET) dosimetry system for dose verification of high dose rate (HDR) brachytherapy treatment planning was investigated. MOSFET detectors were calibrated with a 0.6 cm3 NE-2571 Farmer-type ionization chamber in water. Key characteristics of the MOSFET detectors, such as the energy dependence, that will affect phantom measurements with HDR 192Ir sources were measured. The MOSFET detector was then applied to verify the dosimetric accuracy of HDR brachytherapy treatments in a custom-made water phantom. Three MOSFET detectors were calibrated independently, with the calibration factors ranging from 0.187 to 0.215 cGy∕mV. A distance …

In Vivo Verification Of Superficial Dose For Head And Neck Treatments Using Intensity-Modulated Techniques, Zhen-Yu Qi, Xiao-Wu Deng, Shao-Min Huang, Li Zhang, Zhi-Chun He, X. Allen Li, Ian Kwan, Michael Lerch, Dean Cutajar, Peter Metcalfe, Anatoly Rosenfeld

Dean Cutajar

Skin dose is one of the key issues for clinical dosimetry in radiation therapy. Currently planning computer systems are unable to accurately predict dose in the buildup region, leaving ambiguity as to the dose levels actually received by the patient’s skin during radiotherapy. This is one of the prime reasons why in vivo measurements are necessary to estimate the dose in the buildup region. A newly developed metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector designed specifically for dose measurements in rapidly changing dose gradients was introduced for accurate in vivo skin dosimetry. The feasibility of this detector for skin dose measurements was verified in …

Rapid Synthesis Of Li4ti5o12 Microspheres As Anode Materials And Its Binder Effect For Lithium-Ion Battery, Shulei Chou, Jiazhao Wang, Hua Liu, S. Dou

Shulei Chou

Li4Ti5O12 microspheres composed of nanoflakes were synthesized within 1 h by a combination of a microwave-assisted hydrothermal method and a microwave postannealing process. The Li4Ti5O12 microspheres were characterized by X-ray diffraction, Brunauer–Emmett–Teller N2 adsorption, scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. Sodium carboxymethyl cellulose (CMC) was also investigated as a low-cost green binder. The electrochemical tests, including constant current charge–discharge, cyclic voltammetry, and electrochemical impedance spectroscopy, demonstrated that the electrode using CMC as binder had better high-rate capability than the one with polyvinylidene fluoride (PVDF) binder. The electrode using CMC and PVDF as binder had the same lithium …

Silver-Coated Tio2 Nanostructured Anode Materials For Lithium Ion Batteries, - Md. Mokhlesur Rahman, Jiazhao Wang, David Wexler, Yuyuan Zhang, Xinjun Li, Shulei Chou, Hua Liu

Shulei Chou

Anatase TiO₂ nanoribbons/nanotubes (TiO₂-NRTs) have been synthesised successfully via a reflux method followed by drying in a vacuum oven, and then, silver-coated TiO₂ NRTs (Ag/TiO₂-NRTs) were prepared by coating silver particles onto the TiO₂-NRTs surface by the traditional silver mirror reaction. The physical properties of the synthesised products were examined in detail using X-ray diffraction, field emission gun scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy, respectively. The results indicated that the Ag nanoparticles were uniformly deposited on the surface of the TiO₂ nanoribbons/nanotubes. The electrochemical properties were investigated …

Nanocrystalline Porous A-Life02-C Composite-An Environmentally Friendly Cathode For The Lithium-Ion Battery, Md Mokhlesur Rahman, Jiazhao Wang, Mohd Faiz Hassan, Shulei Chou, Zhixin Chen, Hua Liu

Shulei Chou

A novel nanocrystalline porous α-LiFeO2–C composite with a high surface area of around 115 m2 g−1 has been synthesized by a simple molten salt method, followed by a carbon coating process. The structure and morphology were confirmed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FE-SEM observations demonstrated that the morphology consists of α-LiFeO2–C nanoclusters composed of very tiny nanoparticles joined together by a porous architecture. TEM investigations revealed that amorphous carbon was incorporated into the pores among the nanoparticles and that some nanoparticles were covered by a thin layer of carbon as well. …

Electrodeposition Of Mno2 Nanowires On Carbon Nanotube Paper As Free-Standing, Flexible Electrode For Supercapacitors, Shulei Chou, Jia-Zhao Wang, Sau-Yen Chew, Hua Liu, S Dou

Shulei Chou

MnO2 nanowires were electrodeposited onto carbon nanotube (CNT) paper by a cyclic voltametric technique. The as-prepared MnO2 nanowire/CNT composite paper (MNCCP) can be used as a flexible electrode for electrochemical supercapacitors. Electrochemical measurements showed that the MNCCP electrode displayed specific capacitances as high as 167.5 F g-1 at a current density of 77 mA g-1. After 3000 cycles, the composite paper can retain more than 88% of initial capacitance, showing good cyclability. The CNT paper in the composite acted as a good conductive and active substrate for flexible electrodes in supercapacitors, and the nanowire structure of the MnO2 could facilitate …

Nickel Sulfide Cathode In Combination With An Ionic Liquid-Based Electrolyte For Rechargeable Lithium Batteries, Jiazhao Wang, Shulei Chou, Sau Yen Chew, Jiazeng Sun, Maria Forsyth, Douglas Macfarlane, Hua Liu

Shulei Chou

Nickel sulfides, pure Ni3S2 and a mixture of Ni7S6-NiS, were synthesized through a solvothermal process. The nickel sulphide powders were characterised by X-ray diffraction, scanning electron microscopy, and electrochemical testing. The results showed that the capacity of NiS-Ni7S6 is much higher than that of Ni3S2, when used as the cathode in a lithium cell with an organic solvent-based electrolyte, 1 M lithium bis (trifluoromethanesulfonyl)amide (LiNTf2) in poly(ethylene glycol) dimethyl either 500. The NiS-Ni7S6 electrodes were also tested with an ionic liquid electrolyte consisting of 1 M LiNTf2 in N-methyl-N-propyl pyrrolidinium bis(trifioromethanesulfonyl)amide ([C3mpyr][NTf2]) to compare with organic-solvent based electrolytes. The result …

Electrochemical Deposition Of Porous Co3o4 Nanostructured Thin Film For Lithium-Ion Battery, Shulei Chou, Jiazhao Wang, Hua Liu, S. Dou

Shulei Chou

Porous Co3O4 nanostructured thin films are electrodeposited by controlling the concentration of Co(NO3)2 aqueous solution on nickel sheets, and then sintered at 300C for 3 h. The as-prepared thin films are characterised by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The electrochemical measurements show that the highly porous Co3O4 thin film with the highest electrochemically active specific surface area (68.64 m2 g-1) yields the best electrochemical performance compared with another, less-porous film and with a non-porous film. The highest specific capacity (513 mAh g-1 after 50 cycles) is obtained from the thinnest film with Co3O4 loaded …

The Compatibility Of Transition Metal Oxide/Carbon Composite Anode And Ionic Liquid Electrolyte For The Lithium-Ion Battery, Shulei Chou, Lin Lu, Jiazhao Wang, Md Mokhlesur Rahman, Chao Zhong, Hua Liu

Shulei Chou

Three types of transition metal oxide/carbon composites including Fe2O3/C, NiO/C and CuO/Cu2O/C synthesized via spray pyrolysis were used as anode for lithium ion battery application in conjunction with two types of ionic liquid: 1 M LiN(SO2CF3)2 (LiTFSI) in 1-ethyl-3-methyl-imidazolium bis(fluorosulfonlyl)imide (EMI-FSI) or 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (Py13-FSI). From the electrochemical measurements, the composite electrodes using Py13-FSI as electrolyte show much better electrochemical performance than those using EMI-FSI as electrolyte in terms of reversibility. The Fe2O3/C composite shows the highest specific capacity and the best capacity retention (425 mAh g−1) under a current density of 50 mA g−1 for up to 50 cycles, …

Sno2-Coated Multiwall Carbon Nanotube Composite Anode Materials For Rechargeable Lithium-Ion Batteries, Lukman Noerochim, Jiazhao Wang, Shulei Chou, Huijun Li, Hua Liu

Shulei Chou

SnO₂-coated multiwall carbon nanotube (MWCNT) nanocomposites were synthesized by a facile hydrothermal method. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The SnO₂/MWCNT composites, when combined with carboxymethyl cellulose (CMC) as a binder, show excellent cyclic retention, with the high specific capacity of 473 mAh g⁻¹ beyond 100 cycles, much greater than that of the bare SnO₂ which was also prepared by the hydrothermal method in the absence of MWCNTs. The enhanced capacity retention could be mainly attributed to …

Highly Flexible And Bendable Free-Standing Thin Film Polymer For Battery Application, Jiazhao Wang, Shulei Chou, Hao Liu, Guoxiu Wang, Chao Zhong, Sau Yen Chew, Hua Liu

Shulei Chou

Highly flexible and bendable free-standing polypyrrole (PPy) films were prepared using the electrochemical polymerization method. The paper-like films are soft, lightweight, mechanically robust, and highly electrically conductive. The morphologies and electrochemical behaviour of the free-standing pure PPy films were affected by the electrochemical polymerization conditions. The free-standing films show promise as cathodes for flexible and bendable batteries.

Basic Molten Salt Process-A New Route For Synthesis Of Nanocrystalline Li4ti5o12-Tio2 Anode Material For Li-Ion Batteries Using Eutectic Mixture Of Lino3-Lioh-Li2o2, Md Mokhlesur Rahman, Jiazhao Wang, Mohd Hassan, Shulei Chou, David Wexler, Hua Liu

Shulei Chou

A nanocrystalline Li₄Ti₅O₁₂–TiO₂ duplex phase has been synthesized by a simple basic molten salt process (BMSP) using an eutectic mixture of LiNO₃–LiOH–Li₂O₂ at 400–500 °C. The microstructure and morphology of the Li₄Ti₅O₁₂–TiO₂ product are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The sample prepared by heat-treating at 300 °C for 3 h (S-1) reveals dense agglomerates of ultra-fine nanocrystalline Li₄Ti₅O₁₂; with heat treatment at …