Copper Buildup Research Articles

Ayurvedic Management of Kampavata w.s.r. to Wilsons Disease: A Case Report

Ayurveda has described various disorders along with its prevention as well as it’s cure for disorders. Also, this was described as main aim of Ayurveda [1]. Wilson’s disease is one of the uncommon recessive autosomal diseases which typically manifests before the age of forty. Here, an excessive buildup of copper occurs in the brain and liver. It can be correlated with Kampavata in Ayurveda science. Since it is characterised by Sarvanga Kampa or Shiro Kampa also, it is one of the Vatavyadhis [2]. As in Kampavata, Chala Guna of Vata Dosha excessively increases which causes Kampa in the body parts. In this case study, Shodhana and Shamana Chikitsa were given to the patient in order to manage Kampavata. Matrabasti, Rajayapan Basti along with Shamana Yoga Dravyas were given for the management of this case.

A rare presentation of Wilson disease: a case report

Wilson Disease results from autosomal recessive mutation in ATP7B gene which leads to reduced formation of ceruloplasmin protein in the body that acts as a copper transporter. Due to its deficiency, there is the build-up of copper in the liver and brain among other organ systems and it leads to the development of various clinical abnormalities but commonly presents either as hepatic dysfunction and/or cirrhosis in young patients with movement disorder. Here we present a case that presented with hypoglycemia and hypothermia in absence of any infection, drug abuse or metabolic abnormality. He was later diagnosed as Wilson disease. Wilson Disease is mostly thought of hepatic /neurological disease. Contrary to this Wilson’s disease is a multisystem disease affecting multiple organ system including, kidneys, endocrine system and musculoskeletal system and can present with manifestations of above-mentioned systems.

Indole-based Fluorometric and Colorimetric Chemosensors for the Selective Detection of Cu2+: A Brief Review From the Year 2011-2021

The development of chemosensors has been driven by concurrently advanced research in fluorescence and colorimetric chemosensing. Over the last few decades, the development of copper ion-selective fluorogenic and chromogenic chemosensors has been extensively studied due to their high sensitivity, low cost, and simplicity. They can interact with the metal ion in a unique manner and create measurable color, fluorescence, or redox potential changes. Copper (Cu2+) ion is deemed the third most prevalent transition metal in human beings owing to its various biological and physiological processes. It has drawn a great deal of attention from many researchers in various disciplines such as biology, medicine, and environmental studies. However, an excessive buildup of copper in the body has been linked to several diseases. Thus, more recent research is being focused on developing fluorometric and colorimetric chemosensors for the selective detection of copper ions. Recently, there have been a lot of studies reported in this field of study that describe highly sensitive and sophisticated indole-based chemosensors for various metal ions of interest. In addition, indole derivatives possess inherent fluorescence properties due to their electron-rich nature caused by the π-excessive system of indole, and therefore they can be employed in chemosensors for metal ion detection. Both cations and anions employ it as a molecular recognition system. This review summarizes selective and sensitive Cu2+ ion detection accomplished byvarious indole-based chemosensors between the years 2011 to 2021. Furthermore, sensor design, sensing methods, ligand-metal binding stoichiometry, association constant, and the detection limit by the chemosensors are all summarized and explored.
 Keywords: Indole, Fluorescent chemosensors, Colorimetric chemosensors, Cu2+, Turn-on, Turn-off

New antimicrobials and plant defense inducers for managing citrus canker disease

For over two decades, Florida citrus growers have been heavily using copper sprays to combat citrus canker (Xanthomonas citri subsp. citri; Xcc), but it raises the risk of developing resistant bacterial strains and excessive accumulation in the soil. Alternative methods are needed to reduce copper dependency and better manage Xcc. Therefore, we screened copper-alternative products against canker on young seedlings in the greenhouse and mature trees in a commercial grove in Florida, USA. In the greenhouse, we evaluated the efficacy of single foliar application of new plant defense inducers (PDI), ‘PDI5’, ‘PDI26’, and ‘PDI31’, and a commercially available systemic acquired resistance inducer, Actigard (drench; 2g/tree), applied two days before injection-infiltration with citrus canker bacterium Xcc (104 CFU/ml), on two-year-old Valencia trees. All three PDIs, sprayed at 500 ppm, as well as Actigard (drench), effectively reduced canker severity on the inoculated leaves in the greenhouse (P ≤0.02). In the grove, we tested new antimicrobials, Mastercop ‘MC’ (21.46% copper sulfate pentahydrate; metallic copper equivalent 5.4%) at concentrations of 1.12 kg/ha, 1.68 kg/ha and 2.24 kg/ha, ‘AM’ at 1.68 kg/ha and 2.24 kg/ha, and a nutrient solution (AGRO-MOS) at 1.12 kg/ha for canker suppression on 4–6-year-old Hamlin trees. Kocide 2000 (growers’ standard control; metallic copper equivalent 30%; 3.92 kg/ha) was used as a control check. Although 2021 was not as conducive for citrus canker due to the relatively dry spring months in the field, our results showed that the six sprays of AM (2.24 kg/ha) or MC (1.68 kg/ha, and 2.24 kg/ha), in 2022, provided excellent control of Xcc, with a significant reduction in disease incidence in leaves and fruits, and disease severity in fruits, similar to Kocide 2000. The results indicate that antimicrobials, AM and MC, and plant defense inducers PDI5, PDI26, and PDI31 can be part of an integrated pest management (IPM) program with copper for managing citrus canker. Reducing the frequency and amount of copper applications can help reduce pesticide and application expenses, lower risks of copper buildup in the soil and toxicity for citrus trees and reduce the risk of the emergence of copper-resistant Xcc strains. Further research on these products is needed to assess their long-term effectiveness and potential environmental risks.

Etiology, Histopathology, Staging and Complication of Wilson Disease

Wilsons disease is a disorder that occurs when there are mutations, in the ATP7B gene. This leads to problems with copper transport and metabolism in the body. In this review we explore the causes, effects, symptoms and management of Wilsons disease. We delve into the factors that contribute to the condition and how it affects the livers’ ability to handle copper. A key diagnostic feature is the presence of "sunset glow" hepatocytes indicating a buildup of copper. The disease manifests with symptoms affecting organs such as the liver nervous system, mind, blood, kidneys and eyes. Due to this range of symptoms an accurate diagnosis requires an approach. Prognosis and tailored treatment strategies can be aided by staging using the Leipzig scoring system. We discuss complications associated with Wilsons disease. Highlight its impact on organs underscoring why timely diagnosis is crucial. The management section outlines approaches including medication to remove copper from the body or regulate zinc levels as well as dietary modifications to control copper absorption. Regular monitoring through liver function tests, copper measurements and neurological assessments is essential for managing this condition. Genetic counseling plays a role in helping individuals make decisions about their health when it comes to Wilsons disease. In cases where other treatments have failed or are inadequate, for controlling symptoms or preventing organ damage liver transplantation may be considered as a resort option. Finally, we conclude by highlighting how ongoing research continues to improve our understanding of Wilsons disease and refine methods and treatment strategies.

Cuproptosis-related gene index: A predictor for pancreatic cancer prognosis, immunotherapy efficacy, and chemosensitivity.

AimThe term “Cuproptosis” was coined to describe a novel type of cell death triggered by intracellular copper buildup that is fundamentally distinct from other recognized types such as autophagy, ferroptosis, and pyroptosis in recent days. As the underlying mechanism was newly identified, its potential connection to pancreatic adenocarcinoma (PAAD) is still an open issue.MethodsA set of machine learning algorithms was used to develop a Cuproptosis-related gene index (CRGI). Its immunological characteristics were studied by exploring its implications on the expression of the immunological checkpoints, prospective immunotherapy responses, etc. Moreover, the sensitivity to chemotherapeutic drugs was predicted. Unsupervised consensus clustering was performed to more precisely identify different CRGI-based molecular subtypes and investigate the immunotherapy and chemotherapy efficacy. The expression of DLAT, LIPT1 and LIAS were also investigated, through real-time quantitative polymerase chain reaction (RT-qPCR), western blot, and immunofluorescence staining (IFS).ResultsA novel CRGI was identified and validated. Additionally, correlation analysis revealed major changes in tumor immunology across the high- and low-CRGI groups. Through an in-depth study of each medication, it was determined that the predictive chemotherapeutic efficacy of 32 regularly used anticancer drugs differed between high- and low-CRGI groups. The results of the molecular subtyping provided more support for such theories. Expressional assays performed at transcriptomic and proteomic levels suggested that the aforementioned Cuproptosis-related genes might serve as reliable diagnostic biomarkers in PAAD.SignificanceThis is, to the best of our knowledge, the first study to examine prognostic prediction in PAAD from the standpoint of Cuproptosis. These findings may benefit future immunotherapy and chemotherapeutic therapies.

Epidemiology, Evaluation and Management of Wilson Disease: Review Article

Wilson disease (hepatolenticular degeneration) is a rare autosomal recessive ailment characterized by aberrant copper buildup in the body, with the brain, liver, and cornea being notably affected. Wilson illness is caused by a mutation in the ATP7B gene on chromosome 13, which regulates the protein transporter that excretes excess copper into the bile and out of the body. So far, over 500 mutations have been discovered. The most common treatment for WD is D-penicillamine (D-PCA). Patients with severe spasms, deformities, or dysphonia, as well as those who are allergic to D-PCA, should avoid it. Early Diagnosis is a key factor in saving patient’s live, and thus prober investigation should be done as soon as possible. Family screening is a must when a patient is diagnosed to role out any other patients in the family with the disease and because of the strong genetic factor impacting the disease. early detection is critical for initiating therapy in the early, asymptomatic stages of the disease, rather than when liver decompensation or extensive neurological irreversible harm has already occurred. In this circumstance, the optimum technique is to finish copper investigations in the index patient's first- and second-degree relatives. In the present article we’ll be discussing disease prevalence, etiology and more importantly diagnosis and management.

Interpretation of In-air Output Ratio of Wedged Fields in Different Measurement Conditions

Introduction: The head scatter factor (Sc) is one of the important parameters for monitor unit (MU) calculation. There are multiple factors that impact the Sc values, such as, head structures, back scattering in to dose monitoring chambers, wedges and so on. This study aimed to investigate the variations of SC with different build-up cap materials, wall thickness, Source to Skin Distance (SSDs), ionization chambers and variation of the SC with wedge angles in 6MV photon beam. Materials and Methods: In this study, Copper and Perspex build-up caps were designed and fabricated with two different thicknesses for each build-up cap. Measurements were performed on an Elekta Compact medical linear accelerator (6 MV) using RK with sensitive volume of 0.12 cc and Farmer-type ion chamber with sensitive volume of 0.65 cc. In all measurements, build-up caps and ionization chambers were positioned in a stand vertical to the beam central axis. It is also investigated the effect of different SSDs on SC. Results: The presence of wedge influences the SC values significantly. Variation of SC in open and wedged fields had maximum deviation of 0.9% and 6.8% and minimum of 0.4% and 2.7% for 30° and 60° angles of wedge, respectively. different SSD and type of ion chamber had no significant influence on the SC. In small field sizes, the SC values in copper build-up cap is higher than Perspex and in large field sizes, measured SC in perspex build-up cap is higher than copper. Conclusion: It was found that the presence of internal wedge has significant contribution to head scatter factor and it increases with increasing wedge angle. Therefore, it should be takes into account in manually MU calculations.

Apolipoprotein E deletion has no effect on copper-induced oxidative stress in the mice brain.

The current study was designed to investigate effect of copper administration on oxidative damage to the brain in ApoE−/− mice and to explore the putative neuroprotective effects rendered by apolipoprotein E (ApoE). Male C57BL/6 ApoE−/− and wild-type mice were randomly assigned into four groups, ApoE−/− mice wild-type mice treated with either copper or saline. Copper sulphate pentahydrate or saline (200 µl) were administered intragastrically daily for 12 weeks. Expression of malondialdehyde, superoxide dismutase (SOD), hemeoxygenase 1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO1) were determined by a combination of biochemical assays. The concentration of copper in the brain of C57BL/6 mice and ApoE−/− mice treated by copper significantly increased compared with mice treated by saline (P=0.0099 and P=0.0443). Compared with the C57BL/6 mice treated by copper, the level of the ApoE−/− mice treated by copper was higher (P=0.018). TBARS and SOD activities or the expressions of NQO1 and HO-1 in the brain were not significantly different amongst the four experimental groups of mice. The relative value of NQO1/β-actin expression in the brain of the ApoE−/− mice was similar in both saline and copper administration experimental groups. However, Western blot analysis showed that NQO1 expression was significantly higher in the ApoE−/− mice brain treated with saline compared with saline treated wild-type mice (P=0.0449). ApoE does not function in protecting the brain from oxidative damage resulting from copper build-up in Wilson’s disease, but may play a role in regulating copper accumulation in the brain.

A novel multilayer MV imager computational model for component optimization

A novel Megavoltage (MV) multilayer imager (MLI) design featuring higher detective quantum efficiency and lower noise than current conventional MV imagers in clinical use has been recently reported. Optimization of the MLI design for multiple applications including tumor tracking, MV-CBCT and portal dosimetry requires a computational model that will provide insight into the physics processes that affect the overall and individual components' performance. The purpose of the current work was to develop and validate a comprehensive computational model that can be used for MLI optimization. The MLI model was built using the Geant4 Application for Tomographic Emission (GATE) application. The model includes x-ray and charged-particle interactions as well as the optical transfer within the phosphor. A first prototype MLI device featuring a stack of four detection layers was used for model validation. Each layer of the prototype contains a copper buildup plate, a phosphor screen and photodiode array. The model was validated against measured data of Modulation Transfer Function (MTF), Noise-Power Spectrum (NPS), and Detective Quantum Efficiency (DQE). MTF was computed using a slanted slit with 2.3° angle and 0.1mm width. NPS was obtained using the autocorrelation function technique. DQE was calculated from MTF and NPS data. The comparison metrics between simulated and measured data were the Pearson's correlation coefficient (r) and the normalized root-mean-square error (NRMSE). Good agreement between measured and simulated MTF and NPS values was observed. Pearson's correlation coefficient for the combined signal from all layers of the MLI was equal to 0.9991 for MTF and 0.9992 for NPS; NRMSE was 0.0121 for MTF and 0.0194 for NPS. Similarly, the DQE correlation coefficient for the combined signal was 0.9888 and the NRMSE was 0.0686. A comprehensive model of the novel MLI design was developed using the GATE toolkit and validated against measured MTF, NPS, and DQE data acquired with a prototype device featuring four layers. This model will be used for further optimization of the imager components and configuration for clinical radiotherapy applications.

Controlling Legionella in a UK hospital using copper and silver ionisation—A case study

This paper describes work that evaluated a copper and silver ionisation system, comprising 99.99% copper and 99.99% silver electrodes, installed as a replacement to a low performing chlorine dioxide (ClO2) system for the control of Legionella in a UK hospital. The system was used in conjunction with the existing temperature regime and was installed upstream of the water storage tanks to allow adequate build-up of copper and silver in tanks so that good levels were available for distribution to outlets. Samples were taken monthly and analyzed for Legionella, by the culture method, and for copper and silver by Inductively Coupled Plasma-Optical Emission Spectroscopy/Mass Spectrometry over a four-year period. The results showed that water temperature above 55°C did not control L. pneumophila in 25 out of 140 outlets. The copper and silver ionisation system had initial problems during the commissioning stage and up to four months after commissioning, owing to deadlegs, deadends and low-use outlets. Once these problems were solved, Legionella was controlled consistently and monthly monitoring of outlets has showed no positive result for 15 months. It was concluded that: Legionella could not be effectively controlled using a temperature regime alone, even when temperature was maintained at below 20°C or at above 55°C; and that copper and silver ionisation was effective for Legionella control provided the system was regularly monitored to ensure the required concentration of ions was maintained, so that potential Legionella sources, such as build-up of biofilms in rubber-lined hoses, were dealt with as soon as detected.

Copper deficiency can limit nitrification in biological rapid sand filters for drinking water production

Incomplete nitrification in biological filters during drinking water treatment is problematic, as it compromises drinking water quality. Nitrification problems can be caused by a lack of nutrients for the nitrifying microorganisms. Since copper is an important element in one of the essential enzymes in nitrification, we investigated the effect of copper dosing on nitrification in different biological rapid sand filters treating groundwater. A lab-scale column assay with filter material from a water works demonstrated that addition of a trace metal mixture, including copper, increased ammonium removal compared to a control without addition. Subsequently, another water works was investigated in full-scale, where copper influent concentrations were below 0.05 μg Cu L−1 and nitrification was incomplete. Copper dosing of less than 5 μg Cu L−1 to a full-scale filter stimulated ammonium removal within one day, and doubled the filter's removal from 0.22 to 0.46 g NH4-N m−3 filter material h−1 within 20 days. The location of ammonium and nitrite oxidation shifted upwards in the filter, with an almost 14-fold increase in ammonium removal rate in the filter's top 10 cm, within 57 days of dosing. To study the persistence of the stimulation, copper was dosed to another filter at the water works for 42 days. After dosing was stopped, nitrification remained complete for at least 238 days. Filter effluent concentrations of up to 1.3 μg Cu L−1 confirmed that copper fully penetrated the filters, and determination of copper content on filter media revealed a buildup of copper during dosing. The amount of copper stored on filter material gradually decreased after dosing stopped; however at a slower rate than it accumulated. Continuous detection of copper in the filter effluent confirmed a release of copper to the bulk phase. Overall, copper dosing to poorly performing biological rapid sand filters increased ammonium removal rates significantly, achieving effluent concentrations of below 0.01 mg NH4-N L−1, and had a long-term effect on nitrification performance.

A piecewise-focused high DQE detector for MV imaging.

Electronic portal imagers (EPIDs) with high detective quantum efficiencies (DQEs) are sought to facilitate the use of the megavoltage (MV) radiotherapy treatment beam for image guidance. Potential advantages include high quality (treatment) beam's eye view imaging, and improved cone-beam computed tomography (CBCT) generating images with more accurate electron density maps with immunity to metal artifacts. One approach to increasing detector sensitivity is to couple a thick pixelated scintillator array to an active matrix flat panel imager (AMFPI) incorporating amorphous silicon thin film electronics. Cadmium tungstate (CWO) has many desirable scintillation properties including good light output, a high index of refraction, high optical transparency, and reasonable cost. However, due to the 0 1 0 cleave plane inherent in its crystalline structure, the difficulty of cutting and polishing CWO has, in part, limited its study relative to other scintillators such as cesium iodide and bismuth germanate (BGO). The goal of this work was to build and test a focused large-area pixelated "strip" CWO detector. A 361 × 52 mm scintillator assembly that contained a total of 28 072 pixels was constructed. The assembly comprised seven subarrays, each 15 mm thick. Six of the subarrays were fabricated from CWO with a pixel pitch of 0.784 mm, while one array was constructed from BGO for comparison. Focusing was achieved by coupling the arrays to the Varian AS1000 AMFPI through a piecewise linear arc-shaped fiber optic plate. Simulation and experimental studies of modulation transfer function (MTF) and DQE were undertaken using a 6 MV beam, and comparisons were made between the performance of the pixelated strip assembly and the most common EPID configuration comprising a 1 mm-thick copper build-up plate attached to a 133 mg/cm(2) gadolinium oxysulfide scintillator screen (Cu-GOS). Projection radiographs and CBCT images of phantoms were acquired. The work also introduces the use of a lightweight edge phantom to generate MTF measurements at MV energies and shows its functional equivalence to the more cumbersome slit-based method. Measured and simulated DQE(0)'s of the pixelated CWO detector were 22% and 26%, respectively. The average measured and simulated ratios of CWO DQE(f) to Cu-GOS DQE(f) across the frequency range of 0.0-0.62 mm(-1) were 23 and 29, respectively. 2D and 3D imaging studies confirmed the large dose efficiency improvement and that focus was maintained across the field of view. In the CWO CBCT images, the measured spatial resolution was 7 lp/cm. The contrast-to-noise ratio was dramatically improved reflecting a 22 × sensitivity increase relative to Cu-GOS. The CWO scintillator material showed significantly higher stability and light yield than the BGO material. An efficient piecewise-focused pixelated strip scintillator for MV imaging is described that offers more than a 20-fold dose efficiency improvement over Cu-GOS.

Regional Distribution of Copper, Zinc and Iron in Brain of Wistar Rat Model for Non-Wilsonian Brain Copper Toxicosis.

In previous studies, we have reported first in vivo evidence of copper deposition in the choroid plexus, cognitive impairments, astrocytes swelling (Alzheimer type II cells) and astrogliosis (increase in number of astrocytes), and degenerated neurons coupled with significant increase in the hippocampus copper and zinc content in copper-intoxicated Wistar rats. Nonetheless, hippocampus iron levels were not affected by chronic copper-intoxication. Notwithstanding information on distribution of copper, zinc and iron status in different regions of brain due to chronic copper exposure remains fragmentary. In continuation with our previous study, the aim of this study was to investigate the effects of intraperitoneally injected copper lactate (0.15mg Cu/100g body weight) daily for 90days on copper, zinc and iron levels in different regions of the brain using atomic absorption spectrophotometry. Copper-intoxicated group showed significantly increased cortex, cerebellum and striatum copper content (76, 46.8 and 80.7% increase, respectively) compared to control group. However, non-significant changes were observed for the zinc and iron content in cortex, cerebellum and striatum due to chronic copper exposure. In conclusion, the current study demonstrates that chronic copper toxicity causes differential copper buildup in cortex, cerebellum and striatum region of central nervous system of male Wistar rats; signifying the critical requirement to discretely evaluate the effect of copper neurotoxicity in different brain regions, and ensuing neuropathological and cognitive dysfunctions.

Transit dosimetry in dynamic IMRT with an a-Si EPID.

Using an amorphous silicon (a-Si) EPID for transit dosimetry requires detailed characterization of its dosimetric response in a variety of conditions. In this study, a measurement-based model was developed to calibrate an a-Si EPID response to dose for transit dosimetry by comparison with a reference ionization chamber. The ionization chamber reference depth and the required additional buildup thickness for electronic portal imaging devices (EPID) transit dosimetry were determined. The combined effects of changes in radiation field size, phantom thickness, and the off-axis distance on EPID transit dosimetry were characterized. The effect of scattered radiation on out-of-field response was investigated for different field sizes and phantom thicknesses by evaluation of the differences in image profiles and in-water measured profiles. An algorithm was developed to automatically apply these corrections to EPID images based on the user-specified field size and phantom thickness. The average phantom thickness and an effective field size were used for IMRT fields, and images were acquired in cine mode in the presence of an anthropomorphic phantom. The effective field size was defined as the percentage of the jaw-defined field that was involved during the delivery. Nine head and neck dynamic IMRT fields were tested by comparison with a MatriXX two-dimensional array dosimeter using the Gamma (3%, 3 mm) evaluation. A depth of 1.5 cm was selected as the ionization chamber reference depth. An additional 2.2 mm of copper buildup was added to the EPID. Comparison of EPID and MatriXX dose images for the tested fields showed that using a 10% threshold, the average number of points with Gamma index <1 was 96.5%. The agreement in the out-of field area was shown by selection of a 2% threshold which on average resulted in 94.8% of points with a Gamma index <1. The suggested method is less complicated than previously reported techniques and can be used for all a-Si EPIDs regardless of the manufacturer.

The Modern Treatment of Wilson’s Disease

Wilson’s disease is an inherited defect in biliary copper excretion, causing a buildup of copper and copper toxicity, primarily in liver and brain. Presentation with liver disease and/or neurological disease usually occurs in the second and third decades of life. Recognition of the disease is often delayed, which is unfortunate, because once appropriate treatment is started, progression of the disease can be halted, and further damage avoided. Regarding current treatment, many physicians are only aware of penicillamine, because it was the first orally effective drug developed. However, penicillamine has outlived its usefulness, being more toxic than more recently developed drugs. For the hepatic presentation, a combination of trientine and zinc should be used for 4-6 months, then trientine stopped and zinc used for lifelong maintenance therapy. For the neurological presentation, tetrathiomolybdate should be used if available for 8-16 weeks, then zinc for maintenance. If tetrathiomolybdate is not available, zinc should be used. For presymptomatic patients, zinc should be used from the beginning. Zinc should also be used for pregnant and pediatric patients, with a reduced dose for the latter. Zinc causes gastric intolerance in some patients, so in all cases where zinc is the favored therapy, if it is not tolerated, then trientine should be used as second choice. In too many cases, patients are put on zinc, compliance not monitored, and then papers are written about “zinc failures”. There are no zinc failures, just noncompliance problems.

Alzheimer's disease linked to brain copper buildup

Alzheimer's disease linked to brain copper buildup

Radiation induced current in the RF coils of integrated linac‐MR systems: The effect of buildup and magnetic field

In integrated linac-MRI systems, a measurable radiation induced current (RIC) is caused in RF coils by pulsed irradiation. This work (1) tests a buildup method of RIC removal in planar conductors; (2) validates a Monte Carlo method of RIC calculation in metal conductors; and (3) uses the Monte Carlo method to examine the effects of magnetic fields on both planar conductor and practical cylindrical coil geometries. The RIC was measured in copper and aluminum plates, taken as the RF coil conductor surrogates, as a function of increasing thickness of buildup materials (teflon and copper). Based on the Penelope Monte Carlo code, a method of RIC calculation was implemented and validated against measurements. This method was then used to calculate the RIC in cylindrical coil geometries with various air gaps between the coil conductor and the enclosed water phantom. Magnetic fields, both parallel and perpendicular to the radiation beam direction, were then included in the simulation program. The effect of magnetic fields on the effectiveness of RIC removal with the application of buildup material was examined in both the planar and the cylindrical geometries. Buildup reduced RIC in metal plate conductors. For copper detector∕copper buildup case, the RIC amplitude was reduced to zero value with 0.15 cm copper buildup. However, when the copper is replaced with teflon as buildup atop the copper conductor, the RIC was only reduced to 80% of its value at zero buildup since the true electronic equilibrium cannot be obtained in this case. For the aluminum detector∕teflon buildup case, the initial amplitude of the RIC was reduced by 90% and 92% in planar aluminum conductor and a surface coil, respectively. In case of cylindrical coils made of aluminum, teflon buildup around the coil's outer surface was generally effective but failed to remove RIC when there was an air gap between the coil and the phantom. Stronger magnetic fields (>0.5 T) perpendicular to the beam direction showed a modest decrease in the RIC for planar conductors with buildup. In the cylindrical geometries, the effect of magnetic fields was very small compared to the effect of introducing air gaps. Loss in signal-to-noise ratio (SNR) due to RIC was reduced from 11% to 5% when a simple buildup was applied to the solenoid in a preliminary experiment. The RIC in RF coils results from the lack of electronic equilibrium in the coil conductor as the RIC in planar conductor was completely removed by identical buildup of adequate thickness to create electronic equilibrium. The buildup method of RIC removal is effective in cylindrical coil geometry when the coil conductor is in direct contact with the patient. The presence of air makes this method of RIC removal less effective although placing buildup still reduces the RIC by up to 60%. The RIC Monte Carlo simulation is a useful tool for practical coil design where radiation effects must be considered. The SNR is improved in the images obtained concurrently withradiation if buildup is applied to the coil.

Direct dose to water dosimetry for pretreatment IMRT verification using a modified EPID

Electronic portal imaging devices (EPIDs) are high resolution systems that produce electronic dose maps with minimal time required for equipment setup, and therefore potentially present a time-saving alternative for intensity modulated radiation therapy (IMRT) pretreatment verification. A modified commercial EPID was investigated operated with an opaque sheet blocking the optical signal produced in the phosphor layer as a precursor to a switched mode dual dosimetry-imaging EPID system. The purpose of this study was to investigate the feasibility of using this system for direct dose to water dosimetry for pretreatment IMRT verification. A Varian amorphous silicon EPID was modified by placing an opaque sheet between the Gd(2)S(2)O:Tb phosphor layer and the photodiode array to block the optical photons. The EPID was thus converted to a direct-detecting system (dEPID), in which the high energy radiation deposits energy directly in the photodiode array. The copper build-up was replaced with d(max) solid water. Sixty-one IMRT beams of varying complexity were delivered to the EPID, to EDR2 dosimetric film and to a 2D ion chamber array (MapCheck). EPID data was compared to film and MapCheck data using gamma analysis with 3%, 3mm pass criteria. The fraction of points that passed the gamma test was on average 98.1% and 98.6%, for the EPID versus film and EPID versus MapCheck comparisons, respectively. In the case of comparison with film, the majority of observed discrepancies were associated with problems related to film sensitivity or processing. The very close agreement between EPID and both film and MapCheck data demonstrates that the modified EPID is suitable for direct dose to water measurement for pretreatment IMRT verification. These results suggest a reconfigured EPID could be an efficient and accurate dosimeter. Alternatively, optical switching methods could be developed to produce a dual-mode EPID with both dosimetry and imaging capabilities.

Managing copper in leach solution at the Çöpler gold mine: laboratory testing and process design

Alacer Gold Corporation is constructing the Copler Gold Mine in eastern Turkey. Mining commenced in the fourth quarter of 2009 and gold production started in the fourth quarter of 2010. The mine is a 15,500 t/day oxide heap leach with three-stage crushing, agglomeration, carbon adsorption and electrowinning for final metal recovery. Leach solution copper levels are expected to be relatively low during the first two years of production, but will increase in later years due to higher copper content in the mined and processed ore. Over the mine life, approximately 40 Mt of ore will be placed on the leach pad, which will contain about 35,000 t of copper. Metallurgical testing indicates copper extraction will vary by ore type and, if controls are not implemented, may lead to copper levels exceeding 1,000 mg/L in pregnant solution. High copper levels in leach solution have the deleterious effect of increasing cyanide consumption and potentially overwhelming the ability of the carbon circuit to effectively adsorb the principal economic metals, which in this case are gold and silver. Using data obtained from laboratory leach column testwork, the heap leach facility was modeled using METSIM process simulation software to estimate the build-up of copper in leach solution over the life of the mine. Laboratory testwork was also performed to evaluate process conditions for treating a portion of pregnant leach solution via sulfide addition to precipitate saleable copper as copper sulfide (Cu2S).