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Letteratura scientifica selezionata sul tema "Phantom material"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 20 febbraio 2023

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Articoli di riviste sul tema "Phantom material"

Yin, Jun, Manqi Li, Guangli Dai, Hongzhao Zhou, Liang Ma e Yixiong Zheng. "3D Printed Multi-material Medical Phantoms for Needle-tissue Interaction Modelling of Heterogeneous Structures". Journal of Bionic Engineering 18, n. 2 (marzo 2021): 346–60. http://dx.doi.org/10.1007/s42235-021-0031-1.

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AbstractThe fabrication of multi-material medical phantoms with both patient-specificity and realistic mechanical properties is of great importance for the development of surgical planning and medical training. In this work, a 3D multi-material printing system for medical phantom manufacturing was developed. Rigid and elastomeric materials are firstly combined in such application for an accurate tactile feedback. The phantom is designed with multiple layers, where silicone ink, Thermoplastic Polyurethane (TPU), and Acrylonitrile Butadiene Styrene (ABS) were chosen as printing materials for skin, soft tissue, and bone, respectively. Then, the printed phantoms were utilized for the investigation of needle-phantom interaction by needle insertion experiments. The mechanical needle-phantom interaction was characterized by skin-soft tissue interfacial puncture force, puncture depth, and number of insertion force peaks. The experiments demonstrated that the manufacturing conditions, i.e. the silicone grease ratio, interfacial thickness and the infill rate, played effective roles in regulating mechanical needle-phantom interaction. Moreover, the influences of material properties, including interfacial thickness and ultimate stress, on needle-phantom interaction were studied by finite element simulation. Also, a patient-specific forearm phantom was printed, where the anatomical features were acquired from Computed Tomography (CT) data. This study provided a potential manufacturing method for multi-material medical phantoms with tunable mechanical properties and offered guidelines for better phantom design.

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Zou, Jing, Xiaodong Hu, Hanyu Lv e Xiaotang Hu. "An Investigation of Calibration Phantoms for CT Scanners with Tube Voltage Modulation". International Journal of Biomedical Imaging 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/563571.

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The effects of calibration phantoms on the correction results of the empirical artifacts correction method (ECCU) for the case of tube modulation were investigated. To improve the validity of the ECCU method, the effect of the geometry parameter of a typical single-material calibration phantom (water calibration phantom) on the ECCU algorithm was investigated. Dual-material calibration phantoms (such as water-bone calibration phantom), geometry arrangement, and the area-ratio of dual-material calibration phantoms were also studied. Preliminary results implied that, to assure the effectiveness of the ECCU algorithm, the polychromatic projections of calibration phantoms must cover the polychromatic projection data of the scanning object. However, the projection range of a water calibration phantom is limited by the scan field of view (SFOV), thus leading to methodological limitations. A dual-material phantom of a proper size and material can overcome the limitations of a single-material phantom and achieve good correction effects.

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Manson, Eric Naab, Abdul Nashirudeen Mumuni, Issahaku Shirazu, Francis Hasford, Stephen Inkoom, Edem Sosu, Mark Pokoo Aikins e Gedel Ahmed Mohammed. "Development of a standard phantom for diffusion-weighted magnetic resonance imaging quality control studies: A review". Polish Journal of Medical Physics and Engineering 28, n. 4 (1 settembre 2022): 169–79. http://dx.doi.org/10.2478/pjmpe-2022-0020.

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Abstract Various materials and compounds have been used in the design of diffusion-weighted magnetic resonance imaging (DWMRI) phantoms to mimic biological tissue properties, including diffusion. This review thus provides an overview of the preparations of the various DW-MRI phantoms available in relation to the limitations and strengths of materials/solutions used to fill them. The narrative review conducted from relevant databases shows that synthesizing all relevant compounds from individual liquids, gels, and solutions based on their identified strengths could contribute to the development of a novel multifunctional DW-MRI phantom. The proposed multifunctional material at varied concentrations, when filled into a multi-compartment Perspex container of cylindrical or spherical geometry, could serve as a standard DW-MRI phantom. The standard multifunctional phantom could potentially provide DW-MRI quality control test parameters in one study session.

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Sofyan, Muhammad, Alpha Olivia Hidayati e Anita Nur Mayani. "Pembuatan Phantom dari Gips Sebagai Pengganti Tulang Manusia dan Bahan Akrilik Sebagai Pengganti Soft Tissue". Journal of Health 4, n. 2 (31 luglio 2017): 107. http://dx.doi.org/10.30590/vol4-no2-p107-113.

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Background: Phantom is very important in radiodiagnostic teaching method, especially in the laboratory of radiography. Exposing object in making radiograph have to consider the amount of radiation which is received by the object. In addition, phantoms price are relatively expensive. To resolve this issue, researcher made phantom using gypsum as subtitute material for bone and acrylic for soft tissue. Objective: This research is done to know how to make a genu phantom using gypsum as subtitute material for bone and acrylic for soft tissue. Methods: Research methods are images draft, draft procedures, procedures of use and testing. Phantom testing is done by making radiograph using phantom genu and human genu as object and the the result is compared to know the equation between genu phantom and genu of the human object Results: The result of testing radiograph showed that phantom structure is almost similar to human bone structure, however there are no bone trabecular. While soft tissue between genu phantom and human genu are almost similar. Based on descriptive analysis of densitometry measurement between genu phantom and human genu evidently there are no differences. Conclusion: Gypsum can be used as subtitute material for bone and acrylic as subtitute material for soft tissue, however could not show bone trabecular.

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Engers, Marius, Kent W. Stewart, Jan Liu e Peter P. Pott. "Development of a realistic venepuncture phantom". Current Directions in Biomedical Engineering 6, n. 3 (1 settembre 2020): 402–5. http://dx.doi.org/10.1515/cdbme-2020-3104.

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AbstractVenepuncture is one of the most common invasive procedures performed worldwide, however, complications still occur. Currently, commercial single layer silicone phantoms used for venepuncture training do not accurately imitate the geometry and mechanical properties seen in the various patient groups. This paper presents the development of a realistic artificial venepuncture phantom. Three multilayered tissue phantoms are developed simulating venepuncture sites of paediatric, adult and geriatric patients. Silicone materials of different stiffnesses were selected to imitate the epidermis, dermis, subcutaneous fat, muscle and superficial veins. Singleaxis indentation tests were carried out on silicone samples and the multi-layered phantom inserts to characterize the material properties. The measured Young's moduli for the artificial dermis, fat and muscle show sufficient agreement with corresponding literature values. However, characterization of the complete phantom inserts showed stiffnesses four times larger than prior in-vivo studies. Future studies will work on developing a more comparable in-vivo study.

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Kariyawasam, Lakna N., Curtise K. C. Ng, Zhonghua Sun e Catherine S. Kealley. "Use of Three-Dimensional Printing in Modelling an Anatomical Structure with a High Computed Tomography Attenuation Value: A Feasibility Study". Journal of Medical Imaging and Health Informatics 11, n. 8 (1 agosto 2021): 2149–54. http://dx.doi.org/10.1166/jmihi.2021.3664.

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Introduction: Three-dimensional (3D) printing provides an opportunity to develop anthropomorphic computed tomography (CT) phantoms with anatomical and radiological features mimicking a range of patients’ conditions, thus allowing development of individualised, low dose scanning protocols. However, previous studies of 3D printing in CT phantom development could only create anatomical structures using potassium iodide with attenuation values up to 1200 HU which is insufficient to mimic the radiological features of some high attenuation structures such as cortical bone. This study aimed at investigating the feasibility of using 3D printing in modelling cortical bone with a non-iodinated material. Methods: This study had 2 stages. Stage 1 involved a vat photopolymerisation 3D printer to directly print cube phantoms with different percentage compositions of calcium phosphate (CP) and resin (approach 1), and approach 2 using a material extrusion 3D printer to develop a cube mould for infilling of the CP with hardener as the phantom. The approach able to create the cube phantom with the CT attenuation value close to that of a tibial mid-diaphysis cortex of a real patient, 1475±205 HU was employed to develop a tibial mid-diaphysis phantom. The mean CT numbers of the cube and tibia phantoms were measured and compared with that of the original CT dataset through unpaired t-test. Results: All phantoms were scanned by CT using a lower extremity scanning protocol. The moulding approach was selected to develop the tibia middiaphysis phantom with CT attenuation value, 1434±184 HU which was not statistically significantly different from the one of the original dataset (p = 0.721). Conclusion: This study demonstrates the feasibility to use the material extrusion 3D printer to create a tibial mid-diaphysis mould for infilling of the CP as an anthropomorphic CT phantom and the attenuation value of its cortex matches the real patient’s one.

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Rahman, M. A., Md Tofajjol Hoseen Bhuiyan, M. M. Rahman e M. N. Chowdhury. "Comparative Study of Absorbed Doses in Different Phantom Materials and Fabrication of a Suitable Phantom". Malaysian Journal of Medical and Biological Research 5, n. 1 (30 giugno 2018): 19–24. http://dx.doi.org/10.18034/mjmbr.v5i1.444.

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In Cancer treatment (radiotherapy) centers, Phantom is important in Quality Assurance routine check and absolute dosimetry conformation. Water is IAEA standard phantom material. But it has some technical difficulty in practical uses and other solid phantoms such as Polystyrene, PMMA is very expensive and locally not available. Hence, the purpose of this paper is to find out a phantom that will be technically very sound, cost effective and locally available. This study reveals that paraffin wax, which has some approximately similar properties (i.e. chemical composition, mass density and number of electrons/gram) to water, can be used as alternative of solid water phantom because of their proximity to the dose absorption property of water which is even better than some of the conventional solid phantoms used in radiation dosimetry. It is also found that paraffin wax phantom with air-bubble inside behaves differently to the radiation absorbing dose and therefore in dose absorption and dose conversion (scaling) factor.

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Mufida, Widya, Asih Puji Utami e Sofie Nornalita Dewi. "PEMBUATAN PHANTOM RADIOLOGI BERBAHAN DASAR KAYU LOKAL SEBAGAI PENGGANTI TULANG MANUSIA". Jurnal Imejing Diagnostik (JImeD) 6, n. 1 (5 febbraio 2020): 7–10. http://dx.doi.org/10.31983/jimed.v6i1.5404.

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Background: Phantom radiology is used as a medium of learning as a substitute for human bones. In its use this phantom radiology has economic value high enough to be an obstacle to the learning process. Therefore, it is necessary to make a phantom with basic materials that are easily accessible and have the same density value as human bones.Methods: the method used throughout this study is through an experimental approach. The research stage involves testing the density of wood by comparing the density value of the sample used, determining the composition of the mixture between wood, contrast media and adhesives that produces phantom with the density that most closely resembles bone phantom.Results: From the results of the research, the density value of the anthropomorphic phantom humerus was 9034, and the information obtained for the density value of the four wood phantoms with basal values. Based on the results of the calculation of the density value obtained the highest value on phantom 1 with a density value of 12775, phantom with the lowest density value of 7682, namely the second phantom, the value of wood phantom density is quite close to the density value of anthropomorphic humerus phantom, namely phantom 3 with a density of 8986 and Phantom 4 density which is slightly above the wood Phantom 2 density value is 7773.Conclusions: In this study to produce wood phantom with a density that resembles bone phantom is carried out with local wood base material mixed with BaSO4 contrast media, so that the average density value is 8986 close to the density value in anthropomorphic bone phantom humerus.

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Radaideh, Khaldoon M., Laila M. Matalqah, A. A. Tajuddin, W. I. Fabian Lee, S. Bauk e E. M. Eid Abdel Munem. "Development and evaluation of a Perspex anthropomorphic head and neck phantom for three dimensional conformal radiation therapy (3D-CRT)". Journal of Radiotherapy in Practice 12, n. 3 (22 aprile 2013): 272–80. http://dx.doi.org/10.1017/s1460396912000453.

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AbstractPurposesTo design, construct and evaluate an anthropomorphic head and neck phantom for the dosimetric evaluation of 3D-conformal radiotherapy (3D-CRT) dose planning and delivery, for protocols developed by the Radiation Therapy Oncology Group (RTOG).Materials and methodsAn anthropomorphic head and neck phantom was designed and fabricated using Perspex material with delineated planning target volumes (PTVs) and organs at risk (OARs) regions. The phantom was imaged, planned and irradiated conformally by a 3D-CRT plan. Dosimetry within the phantom was assessed using thermoluminescent dosimeters (TLDs). The reproducibility of phantoms and TLD readings were checked by three repeated identical irradiations. Subsequent three clinical 3D-CRT plans for nasopharyngeal patients have been verified using the phantom. Measured doses from each dosimeter were compared with those acquired from the treatment planning system (TPS).ResultsPhantom's measured doses were reproducible with <3·5% standard deviation between the three TLDs’ repeated measurements. Verification of three head and neck 3D-CRT patients’ plans was implemented, and good agreement between measured values and those predicted by TPS was found. The percentage dose difference for TLD readings matched those corresponding to the calculated dose to within 4%.ConclusionThe good agreement between predicted and measured dose shows that the phantom is a useful and efficient tool for 3D-CRT technique dosimetric verification.

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Geso, Moshi, Salem Saeed Alghamdi, Abdulrahman Tajaldeen, Rowa Aljondi, Hind Alghamdi, Ali Zailae, Essam H. Mattar et al. "Modified Contrast-Detail Phantom for Determination of the CT Scanners Abilities for Low-Contrast Detection". Applied Sciences 11, n. 14 (20 luglio 2021): 6661. http://dx.doi.org/10.3390/app11146661.

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Computerised tomography (CT) continues to be a corner stone medical and radiologic imaging modalities in radiology and radiotherapy departments. Its importance lies in its efficiency in low contrast detectability (LCD). The assessment of such capabilities requires rigorous image quality analysis using special designed phantoms with different densities as well as variation in atomic mass numbers (A) of the material. Absence of such ranges of densities and atomic mass numbers, limits the dynamic range of assessment. An example is Catphan phantom which represents only three subject contrast levels 0.3, 0.5 and 1 per cent. This project aims to present a phantom with extended range of available subject contrast to include very low-level values and to increase its dynamic scale. With this design, a relatively large number of different contrast objects (holes) can be presented for imaging by a CT scanner to assess its LCD ability. We shall thus introduce another LCD phantom to complement the existing ones, such as Catphan. The cylindrical phantom is constructed using Poly (methyl methacrylate) (PMMA), with craters (holes) having dimensions that gradually increase from 1.0 to 12.5 mm penetrated in configuration that extend from the centre to the corner. Each line of the drilled holes in the phantom is filled with contrast material of specific concentrations. As opposed to the phantom of low detail contrast used in planar imaging, the iodine (contrast material) in this phantom replaces the depth of the phantom holes. The iodine could be reduced to 0.2 l milli-Molar (mM) and can be varied for the next line of holes by a small increment depending on the required level of contrast detectability assessment required.

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Più fonti

Tesi sul tema "Phantom material"

Bauk, Sabar. "Hydrophilic copolymer material characterisation in the mammographic energy region by transmission tomography". Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/843517/.

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Mammographic techniques used for screening programmes need to be of the highest quality; hence, the need of a good phantom to mimic breast response to radiation. The phantom materials must be sensitive to small changes in the mammography system and provide a means of evaluating the absorbed dose to the breast. These materials have to provide the same attenuation properties as the real tissues being simulated, for the radiation modalities being investigated. Cross-linked hydrophilic copolymers have the potential to be good phantom materials for the breast as their elemental compositions are similar to soft tissue. Two types of hydrophilic copolymer materials used in this study were designated as ED1S and ED4C. They were made from a certain proportionate mixture of methyl methacrylate and vinyl pyrrolidone. The physical properties of the materials such as liquid uptake and dimensional changes in hydration and dehydration processes were studied. The equilibrium water content of ED1S and ED4C fully hydrated in water was 55% and 70% respectively. The samples underwent distortion when dehydrated and a volume approximation formula for the dehydrated samples was derived. The linear attenuation coefficient and the mass attenuation coefficient of the hydrophilic copolymer materials at photon energies in the mammographic energy region were determined. Both a single beam transmission method and a photon transmission tomography method were used. The results were compared with XCOM calculated attenuation coefficients of water and average breasts using the elemental composition found in the literature. It was found that the mass attenuation coefficient of dry hydrophilic copolymer samples closely fit the XCOM calculated old-age breast (Breast 3) and samples fully hydrated in water fit the calculated young-age breast (Breast 1). Measurements were also carried out to determine the linear attenuation coefficient of normal and abnormal breast tissues at four photon energies in the mammographic energy region. The values found were in good accord with calculated average breast values. However, more studies need to be done as only three samples were used. The electron density of the hydrophilic copolymer materials was determined by using the Compton scattering technique. The electron density for dry ED1S sample was (3.1 +/- 0.4) x 1023 electrons per cm3 and for dry ED4C was (4.4 +/- 0.4) x 1023 electrons per cm3.

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Aldousari, Hanan. "Study of 2-to-3 photon annihilation using hydrophilic material as hypoxic tumour phantom". Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616952.

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The use of three gamma annihilation as a new PET molecular imaging modality which can predict tumour hypoxia was proposed by Kacperski and Spyrou in 2004. The positronium and its annihilation, could then serve as an oxygen-sensitive marker. The relative magnitude of three photon annihilation is increased in an oxygen deficient environment. The main questions addressed in this thesis are the potential use of the lanthanum bromide LaBr3: Ce (5%) scintillator detector for three-photon positron annihilation measurements. Also, the optimum source-to-detector distance that achieves good efficiency and sensitivity of the measurements. The other question is finding the best method to prepare in vitro three types of hypoxic samples (mineral water, defibrinated horse blood and semm). In addition, the suitability of the hydrophilic material is examined in terms of hydration behaviour, radiation and physical properties, for use as a phantom that represents the hypoxic tumour in the three-photon positron annihilation measurements. The main critical question is which the best method that could be used to measure the three-photon positron annihilation yields. Also, how does the 3y/2y ratio vary with different oxygen concentrations in different hydrophilic materials? Lanthanum bromide LaBr3: Ce (5%) scintillator detectors have good fast timing resolution, good stopping power and large light output. The LaBr3:Ce (5%) has very good scintillator characteristics, combining high effective Z and density, fast decay time, light emission wavelengths matching that of commonly available photon detectors and excellent energy resolution (~3% at 662 keY). However, it is highly hygroscopic in nature, making it difficult to produce, but its commercial availability has been gradually increasing in recent times. LaBr3: Ce (5%) has come to be accepted for the superior energy resolution it offers. Therefore, LaBr3: Ce (5%) detectors can be considered as the scintillators of choice for determining the yield of 2-and3-y positron annihilation. The characterisation of the detector used was can-ied out in terms of energy resolution and efficiency. The effect of amplifier parameters on the energy resolution was also studied. The 'geometrical solid angles subtended by the source-to-detector distances play an important role in the sensitivity and accuracy of the detector efficiency measurements. Therefore, the efficiency measurements were investigated at various distances to optimise the geometrical solid angle for the LaBr3: Ce (5%) detector for the three photon annihilation measurements. The experimental data were compared with the GATE simulated results obtained. The objective to study the factors that affect dissolved oxygen (DO) in three types of samples (mineral water, defibrinated horse blood and semm) was to investigate the 3y/2y ratio in hypoxic, nOlIDoxic and hyperoxic conditions of tissues for future application in oncology in the detection and quantification of tumour hypoxia. This was achieved by measuring the DO, pH and temperature before, during and after treating the samples with nitrogen, carbon dioxide and ascorbic acid (AnaeroGen). Two methods for the preparation of the in vitro hypoxic samples were investigated and evaluated. Carbon dioxide proved to be most effective for the reduction of DO in the samples. Blood tended to resist DO reduction since it decreased at a much slower rate than in water and semm. Together with the fact that the oxygen level in blood remained low after the end of exposure to the gases and ascorbic acid suggests that the solubility of oxygen in blood depends upon the concentration of haemoglobin as well as upon ligands such as CO2 • CO2 combines with haemoglobin affecting oxygen binding and fonns bicarbonate which further decreases the affinity of haemoglobin to oxygen Hydrophilic materials.

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Waiter, Gordon David. "The NMR proton relaxation effectiveness of paramagnetic metal ions and their potential as MRI contrast agents". Thesis, University of Aberdeen, 1995. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU077829.

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Paramagnetic lanthanide ions have been investigated as possible MIR phantom materials and contrast agents. The aim of this study is to determine if it is possible to apply the well known Solomon-Bloembergen equations to solutions of paramagnetic lanthanide ions that have fast electron spin relaxation times, compared to Gadolinium, the most widely used ion for NMR. Studies of the relaxivity, frequency and temperature dependence, show that there is a considerable difference in those properties over the series. Chelation of the ions to EDTA and DTPA resulted in a decrease in the relaxivity which was directly proportional to the decrease in the number of water molecules in the inner co-ordination sphere. The fit of the Solomon-Bloembergen equations to the variable frequency and temperature relaxation times showed that theory is valid for the fast electron spin ions and allowed the calculation of the electron spin relaxation times. This showed that there is a difference of 5 orders of magnitude between Gadolinium, the ion demonstrated to have a slow electron spin relaxation time, and the remaining ions. The addition of EDTA chelated forms of these ions to agarose gels produced NMR phantom materials with relaxation time characteristics that could be chosen to fulfil a desired application. The biodistribution of Gd-DTPA was investigated using ESR and NMR. The concentration of Gd-DTPA in excised rat tissue, 20 minutes after intraperitoneal injection, was determined, by the change in NMR water proton relaxation time from that of a control tissue, and by ESR from direct measurement of the microwave power absorbed by the sample, which is directly proportional to the number of unpaired electron spins in the sample. The results from these two methods of determining contrast agent concentration agree well with each other both in the order of biodistribution and on the absolute concentrations.

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Pakleppa, Markus. "Development of a colonoscopy simulator for the evaluation of colonoscopy devices". Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/33a20ce1-cb9e-4f55-8714-3f6762a16b75.

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Colonoscopy is the current standard for colorectal cancer screening. This procedure requires improvement since it causes patient pain and can even result in injury. Novel colonoscopy devices have to be evaluated to gain information about their performance. At the preclinical stage of the device development the evaluation is typically performed in laboratory experiments. For these experiments an artificial environment is required which can recreate the anatomical and biomechanical features of the colon. A colonoscopy simulator for the evaluation of colonoscopy devices was developed within the ERC funded CoDIR project (Colonic Disease Investigation by Robotic Hydrocolonoscopy). The here developed simulator had to provide a colon phantom with realistic biomechanical properties as well as a sensor setup to measure signals which can be used to quantify the performance of devices which are tested within the simulator. Related literature was reviewed and possible tissue mimicking materials were selected. The suitability of the selected materials was evaluated by testing the frictional and elastic properties of the materials and subsequently comparing the results to those of colon tissue. PVA cryogel was selected as the most suitable material as it exhibits comparable elasticity and coefficients of friction. The tissue mimicking materials were mould casted into phantoms which were designed to represent the anatomical features of the colon. A simulator environment was developed which integrates the phantom as well as force and pressure sensors into a functional system. The sensors measure mesenteric forces and intraluminal pressures which can be related to the performance of tested devices. The simulator allows the arrangement of the sensors and the phantoms in an adjustable, modular approach. The simulator environment was successfully applied in the evaluation of a novel colonoscopy device. The results indicate that PVA cryogels exhibit unique mechanical properties which can be compared to those of colon tissue. The developed colonoscopy simulator provides a promising tool which can aid the development of novel colonoscopy devices.

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Gagne, Matthew P. "The design and implementation of a CT and MRI compatible multipurpose phantom: testing the effectiveness of multiple contrast material concentrations for CTA". Thesis, Boston University, 2013. https://hdl.handle.net/2144/12103.

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Thesis (M.A.)--Boston University
The purpose of our study was to determine if it is possible to acquire CTA images of small vessels using lower concentrations of iodinated contrast material without substantially diminishing image quality. A custom designed multi-purpose phantom was used to test multiple concentrations of iodinated contrast material using low x-ray tube voltage experimental CTA protocols. A single scan using 120 kVp and Noise Index at a setting of 23 was compared to scans using 100 kVp and 80 kVp tube voltages and Noise Index settings of 23, 21, and 19. Lower tube voltages did produce increased attenuation in contrast material regions of interest, however, increased image noise caused the CNR and FOM for the currently established imaging protocol to be superior to the experimental protocols tested. Despite minor decreases in image quality, the experimental imaging protocols were able to produce images utilizing significantly decrease levels of radiation dose. Given minor changes in imaging quality, the ability to substantially reduce dose while maintaining a satisfactory level of image quality was positive. Further experimentation with low kVp CTA imaging utilizing additional NI settings is warranted to measure possible further improvements in image quality while still maintaining low radiation dose.

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Chan, Kin Wa (Karl), University of Western Sydney, of Science Technology and Environment College e School of Computing and Information Technology. "Lateral electron disequilibrium in radiation therapy". THESIS_CSTE_CIT_Chan_K.xml, 2002. http://handle.uws.edu.au:8081/1959.7/538.

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The radiation dose in radiation therapy is mainly measured by ion chamber. The ion chamber measurement will not be accurate if there is not enough phantom material surrounding the ion chamber to provide the electron equilibrium condition. The lack of electron equilibrium will cause a reduction of dose. This may introduce problems in treatment planning. Because some planning algorithms cannot predict the reduction, they over estimate the dose in the region. Electron disequilibrium will happen when the radiation field size is too small or the density of irradiated material is too low to provide sufficient electrons going into the dose volume. The amount of tissue required to provide electron equilibrium in a 6MV photon beam by three methods: direct calculation from Klein-Nisina equation, measurement in low density material phantom and a Monte Carlo simulation is done to compare with the measurement, an indirect method from a planning algorithm which does not provide an accurate result under lateral electron disequilibrium. When the error starts to happen in such planning algorithm, we know that the electron equilibrium conditions does not exist. Only the 6MV photon beam is investigated. This is because in most cases, a 6MV small fields are used for head and neck (larynx cavity) and 6MV fields are commonly used for lung to minimise uncertainity due to lateral electron at higher energies.
Master of Science (Hons)

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Westin, Robin. "Three material decomposition in dual energy CT for brachytherapy using the iterative image reconstruction algorithm DIRA : Performance of the method for an anthropomorphic phantom". Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-91297.

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Brachytherapy is radiation therapy performed by placing a radiation source near or inside a tumor. Difference between the current water-based brachytherapy dose formalism (TG-43) and new model based dose calculation algorithms (MBSCAs) can differ by more than a factor of 10 in the calculated doses. There is a need for voxel-by-voxel cross-section assignment, ideally, both the tissue composition and mass density of every voxel should be known for individual patients. A method for determining tissue composition via three material decomposition (3MD) from dual energy CT scans was developed at Linköping university. The method (named DIRA) is a model based iterative reconstruction algorithm that utilizes two photon energies for image reconstruction and 3MD for quantitative tissue classification of the reconstructed volumetric dataset. This thesis has investigated the accuracy of the 3MD method applied on prostate tissue in an anthropomorphic phantom when using two different approximations of soft tissues in DIRA. Also the distributions of CT-numbers for soft tissues in a contemporary dual energy CT scanner have been determined. An investigation whether these distributions can be used for tissue classification of soft tissues via thresholding has been conducted. It was found that the relative errors of mass energy absorption coefficient (MEAC) and linear attenuation coefficient (LAC) of the approximated mixture as functions of photon energy were less than 6 \% in the energy region from 1 keV to 1 MeV. This showed that DIRA performed well for the selected anthropomorphic phantom and that it was relatively insensitive to choice of base materials for the approximation of soft tissues. The distributions of CT-numbers of liver, muscle and kidney tissues overlapped. For example a voxel containing muscle could be misclassified as liver in 42 cases of 100. This suggests that pure thresholding is insufficient as a method for tissue classification of soft tissues and that more advanced methods should be used.

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Cabrelli, Luciana Camargo. "Desenvolvimento de materiais mimetizadores de tecidos aplicados a técnicas ópticas e ultrassônicas de imagem". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-28102015-135333/.

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Um mimetizador de tecido, mais conhecido como phantom, é um objeto que mimetiza tecidos biológicos e são importantes para caracterização e calibração de equipamentos de imagens médicas como ultrassonografia, e no desenvolvimento de novas modalidades de imagens como a fotoacústica. Este trabalho aborda o desenvolvimento de um gel à base de óleo mineral e polímeros para phantom para aplicações em técnicas acústicas e ópticas. Os polímeros utilizados foram o elastômero tribloco tipo estireno-etileno/butileno-estireno (SEBS) e o polietileno de baixa densidade (PEBD). Foram confeccionados três grupos géis poliméricos com porcentagem de SEBS entre 5%-15% de SEBS, 0%-9% de PEBD. Os géis foram caracterizados acusticamente pela velocidade do som e coeficiente de atenuação através de transdutores de imersão com frequências entre 2,25 MHz-10 MHz, e opticamente entre 400-1200 nm pelos coeficientes de absorção, espalhamento e Albedo. Foi observada velocidade do som entre 1458,6 ± 3,1 m/s e 1480,7 ± 1,9 m/s, sendo compatíveis com valores para gordura; coeficiente de atenuação entre 0,6 ± 0,1 dB/cm a 2,25 MHz e 11,3 ± 0,1 dB/cm a 10 MHz, compatíveis para tecidos moles; coeficiente de absorção em 532 nm entre 0,11-2,62 cm-1 e em 1064 nm entre 0,09-1,70 cm-1, e uma banda de absorção em torno de 930 nm com gordura; o coeficiente de espalhamento em 532 nm entre 0,15 -3,96 cm-1 e em 1064 nm entre 0,17- 3,20 cm-1, valores inferiores para tecidos moles. O coeficiente Albedo mostrou que os géis apresentam caráter absorvedor entre 400-1200 nm. Foi desenvolvido um phantom para imagem por fotoacústica com um dos géis estudados (7%SEBS/5%PEBD) e com uma inclusão com pigmento de urucum e foram feitas imagens fotoacústicas em 532 nm e 1024 nm. Foi observado o sinal fotoacústico mais intenso para a imagem em 532 nm. Com este trabalho pode-se obter uma boa caracterização acústica e óptica de géis formados a partir de polímeros do tipo SEBS em conjunto com o PEBD ainda não descritos na literatura. Os materiais desenvolvidos se mostraram bons mimetizadores para tecidos compostos de gordura e com potencial para aplicações em fotoacústica.
Phantoms are structures composed by materials that mimic specific properties of biological tissues and they are commonly used to calibrate and characterize current medical imaging techniques such as ultrasound and optical imaging, and new imaging modalities such as photoacoustics. In this dissertation we developed an oil-based tissue mimicking gel material with mineral oil, triblock copolymer styrene-ethylene/butylene styrene (SEBS) and low-density polyethylene (LDPE). The gel phantoms were prepared mixing SEBS and LDPE in mineral oil at room temperature, varying the SEBS concentration between 5%15%, and low-density polyethylene (LDPE) between 0%-9% and glass microspheres. Acoustic properties such speed of sound and attenuation coefficient were measured using five unfocused ultrasound transducers with frequencies ranging between 2.2510 MHz. Optical properties such albedo, scattering and absorption coefficients ranging from 400-1200 nm were measured. Speed of sound from 1458.6 ± 3.1m/s and 1480.7 ± 1.9 m/s, and attenuation from 0.6 ± 0.1 dB/cm at 2.25 MHz and 11.3 ± 0.1 dB/cm at 10 MHz were observed. Absorption coefficient at 532 nm between 0.11-2.62 cm-1; at 1064 nm between 0.09-1.70 cm-1 were observed. Peak absorption around 930 nm was observed for all gels. Scattering coefficient at 532 nm between 0.15 -3.96 cm-1 and at 1064 nm between 0.17-3.20 cm-1 were found. Albedo coefficient showed that gels are absorptive characteristic for the selected range of wavelength. A phantom made with a 7% SEBS/5% LDPE gel containing an optical-absorber spherical inclusion made with the same material and annatto were developed. Photoacoustic spectroscopic images of the phantom were acquired using a laser operating at 532 nm and 1064 nm. The photoacoustic signal from the inclusion showed the highest intensities at 532 nm with as expected according to the measured absorption spectrum of annatto. With this dissertation we obtained a suitable acoustic and optical characterization of the SEBS/LDPE gels that was not described in the literature. The materials developed seem suitable to mimic fat tissue and have potential for applications in photoacoustics.

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Hutchinson, Jesson. "Handheld gamma-ray spectrometry for assaying radioactive materials in lungs". Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-11102005-164303/.

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Abrahão, Michelle Ferreira da Costa. "Desenvolvimento de blendas reticuladas de gelatina e PVA para uso em phantoms para treinamento em procedimentos médicos guiados por ultrassom". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-02012018-165534/.

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Abstract (sommario):

Mimetizadores do tecido biológico são objetos capazes de simular as propriedades mecânicas e acústicas do tecido biológico e são comumente chamados de phantoms. São utilizados para avaliar e calibrar equipamentos de ultrassom, auxiliar no desenvolvimento de transdutores, sistemas computacionais ou técnicas de diagnóstico e para treinamento em procedimentos médicos guiados por ultrassom, tais como biópsia de tireóide e mama, anestesia regional, entre outros. O objetivo deste trabalho foi avaliar o efeito da reticulação com glutaraldeído sobre as propriedades das blendas gelatina/poli (álcool vinílico) visando à produção de um material para ser usado como mimetizador do tecido biológico para ultrassonografia (phantoms). Inicialmente blendas de gelatina/PVA com diferentes concentrações dos polímeros na mistura (80/20, 60/40 e 40/60) foram preparadas e caracterizadas. Posteriormente, estas blendas foram reticuladas com 0,5% de glutaraldeído em pH 4 e 5 durante 5, 15, 30 e 60 min, e também com 1,0% de glutaraldeído em pH 5 durante 5min, pois observou-se que este tempo foi suficiente para obter um material com boas propriedades. As blendas foram caracterizadas em função de suas propriedades mecânicas, ângulo de contato, perda de umidade, velocidade de propagação do som e coeficiente de atenuação acústica. A concentração dos polímeros na blenda influenciou nas propriedades mecânicas, higroscópicidade e na perda de umidade dos géis formados. Assim, um aumento na concentração de PVA diminuiu a rigidez e o módulo de Young, e aumentou a velocidade do som das blendas gelatina/PVA. Acima de 60% de PVA houve separação de fases nas blendas com e sem reticulação. A reticulação com glutaraldeído aumentou a rigidez e diminuiu a hidrofilicidade da blenda. A blenda gelatina/PVA 80/20 reticulada com 0,5% de glutaraldeído em pH 5 apresentou as características mais promissoras para o desenvolvimento de materiais mimetizadores do tecido biológico.
Tissue mimicking materials are objects capable of mimic mechanical and acoustic properties of biological tissues and are commonly called phantoms. These objects are used to evaluate and calibrate ultrasound machines, development ultrasound transducer, informatics system or diagnostic techniques and for ultrasound-guided procedures training such as thyroid and breast biopsy, regional anesthesia, and others. The aim of this study was to evaluate the effect of the cross-linked of gelatin/polyvinyl alcohol (PVA) blends utilizing glutaraldehyde, resulting in a material for applications in ultrasound guided training phantoms. Gelatin/PVA blends were prepared with different concentrations of each polymer (80/20, 60/40, and 40/60) and characterized. Also, the same concentrations of the blends were cross-linked using 0.5% glutaraldehyde at pH4 and 5 for 5, 15, 30 and 60 minutes, and 1.0 % of glutaraldehyde at pH 5 for 5 minutes. The resulting blends were characterized by mechanical properties, contact angle, moisture loss, speed of sound and acoustic attenuation. The concentration of the polymers influenced over the mechanical properties, hygroscopicity e moisture loss of the manufactured blends. The increase of the amount of the PVA in the manufactured blends decreased the stiffness and increased the acoustic attenuation, moisture loss, hygroscopicity and speed of sound. Blends with more than 60% of PVA resulting in phase separation of the material. Glutaraldehyde cross-linked gelatin/PVA blend with a proportion of 80/20 with 0.5% of glutaraldehyde at pH 5 presented the most suitable properties for ultrasound-guided training phantoms.

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Libri sul tema "Phantom material"

Juster, Norton. The Phantom Tollbooth. New York, USA: Bullseye Books, 2000.

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Juster, Norton. The phantom tollbooth. 5^a ed. New York: Alfred A. Knopf, 2011.

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Juster, Norton. The phantom tollbooth. Bath: Chivers, 1989.

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Juster, Norton. The phantom tollbooth. London: Collins, 1987.

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Juster, Norton. The Phantom Tollbooth. 3^a ed. New York: Random House, 1996.

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Juster, Norton. The Phantom Tollbooth. London: Lions, 1992.

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Juster, Norton. The phantom tollbooth. London: Collins, 1995.

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Juster, Norton. The Phantom Tollbooth. London: Collins, 1999.

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Juster, Norton. The phantom tollbooth. New York: Random House, 1989.

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Juster, Norton. The Phantom Tollbooth. 5^a ed. New York: Alfred A. Knopf, 1996.

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Capitoli di libri sul tema "Phantom material"

Rigauts, H., G. Marchal, A. L. Baert e R. Hupke. "Spiral Scanning: Phantom Studies and Patient Material". In Advances in CT, 65–76. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-95617-1_6.

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Sari, Ayu Wita, Putri Winda Loja Bimantari e Nadela Putri Sakhia. "Development of Phantom Radiology Using Eggshells Powder as Bone Genu Material". In Proceedings of the 1st International Conference on Electronics, Biomedical Engineering, and Health Informatics, 549–55. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6926-9_48.

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Chen, Feiyu, David D. Pokrajac, Xiquan Shi, Fengshan Liu, Andrew D. A. Maidment e Predrag R. Bakic. "Simulation of Three Material Partial Volume Averaging in a Software Breast Phantom". In Breast Imaging, 149–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31271-7_20.

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Cygan, Szymon, Jakub Żmigrodzki, Beata Leśniak-Plewińska, Maciej Karny, Zbigniew Pakieła e Krzysztof Kałużyński. "Influence of Polivinylalcohol Cryogel Material Model in FEM Simulations on Deformation of LV Phantom". In Functional Imaging and Modeling of the Heart, 313–20. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-20309-6_36.

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Kiel-Jamrozik, Marta, Wojciech Jamrozik, Mateusz Pawlik e Jakub Goczyla. "Impact of 3D Printing Materials on Bone Phantom Features". In Innovations in Biomedical Engineering, 179–86. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99112-8_19.

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Dewi, Dyah Ekashanti Octorina, e Nurul Shafiqa Mohd Yusof. "Tissue-Mimicking Materials for Cardiac Imaging Phantom—Section 1: From Conception to Materials Selection". In Cardiovascular Engineering, 3–33. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-8405-8_1.

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Kairn, T., S. B. Crowe e T. Markwell. "Use of 3D Printed Materials as Tissue-Equivalent Phantoms". In IFMBE Proceedings, 728–31. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19387-8_179.

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Ling, Hang Yin, P. Carrie Choi, Y. P. Zheng e Alan Kin Tak Lau. "Study on the Mechanical Properties of Tissue-Mimicking Phantom Composites Using Ultrasound Indentation". In Advances in Composite Materials and Structures, 133–36. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-427-8.133.

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Yusof, Nurul Shafiqa Mohd, e Dyah Ekashanti Octorina Dewi. "Tissue-Mimicking Materials for Cardiac Imaging Phantom—Section 2: From Fabrication to Optimization". In Cardiovascular Engineering, 35–63. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-8405-8_2.

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Stich, Manuel, Karina Schuller, Anne Slawig, Klaus Detmar, Michael Lell, Sebastian Buhl e Ralf Ringler. "Material Analysis for a New Kind of Hybrid Phantoms Utilized in Multimodal Imaging". In IFMBE Proceedings, 21–28. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-9035-6_4.

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Atti di convegni sul tema "Phantom material"

Meral, Faik Can, Thomas J. Royston e Richard L. Magin. "Fractional Order Models for Viscoelasticity of Soft Biological Tissues". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68137.

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Dynamic mechanical properties of soft tissues provide information that may be used in medical diagnosis. Developing a better fundamental understanding of the governing constitutive relations could improve diagnostic techniques. The mechanical behavior of soft tissues and tissue mimicking phantoms, such as gels, can be represented by viscoelastic material models. Static loading of viscoelastic materials yields information related to elasticity, creep and stress relaxation. However, a broader measure of rate-dependent properties that affect mechanical wave propagation and wave attenuation in such materials can only be extracted from measured response to dynamic excitation. The well known linear viscoelastic material models of Voigt, Maxwell and Kelvin cannot represent the more complicated frequency dependency of these materials over a broad spectral range. Therefore, fractional calculus methods have been considered to model the viscoelastic behavior of soft tissue-like materials. Fractional order models capture the viscoelastic material behavior using fractional orders of differential equations that may yield a more accurate representation of viscoelastic material behavior. This paper focuses on experimental measurements on the tissue mimicking phantom, CF11. Surface waves on the phantom material are studied experimentally and theoretically. Theoretical calculations using linear and fractional order methods are compared with experimental measurements.

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Fivez, Christiaan M., Patrick Wambacq, Paul Suetens e Emile P. Schoeters. "Calibration phantom for dual-energy basis material absorption measurements". In Medical Imaging 1996, a cura di Richard L. Van Metter e Jacob Beutel. SPIE, 1996. http://dx.doi.org/10.1117/12.237822.

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Yan, Karen Chang, Mary Kate McDonough, James J. Pilla e Chun Xu. "Stiffness Characterization Using a Dynamic Heart Phantom and Magnetic Resonance Imaging". In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65222.

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Heart disease is the number one cause of death in the United States [1]. Cardiac Magnetic Resonance Imaging (MRI) technology can be used to diagnose and evaluate a number of diseases and conditions such as coronary artery disease, damage caused by a heart attack, heart failure, and heart valve problems etc. Given the inherent difficulty in imaging the heart in motion, many efforts have been made to improve cardiac motion tracking and eliminate motion related artifacts. A dynamic heart phantom (DHP) capable of simulating true physiological motions is a valuable research tool for improving quality of MR images and determining critical diagnostic information. For instance, MR images have been used to quantify myocardial strain and estimate soft tissue material parameters and in turn to learn about cardiac structure and function [2–4]. In these studies, heart phantoms made of rubber like materials with known material properties are often used as a mean of validation.

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Francis, Alex, Ilya Avdeev, Calvin Berceau, Hugo Pires Lage Martins, Luke Steinbach, Justin Mursch e Vincent Kanack. "Phantom Battery Pack for Destructive Testing of Li-Ion Batteries". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67881.

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The objective of this study is to find a structural alternative to jellyroll in order to safely conduct experimental crash testing of lithium-ion battery packs in academic laboratory environment. A procedure for lateral impact experiments has been developed and conducted on cylindrical cells and phantom cells using a flat rigid drop cart in a custom-built impact test apparatus. The main component of a cylindrical cell, jellyroll, is a layered spiral structure which consists of thin layers of electrodes and separator material. We investigate various phantom materials — candidates to replace the layered jellyroll with a homogeneous anisotropic material. During our experimentation with various phantom cells, material properties and internal geometries of additively manufactured components such as in-fill pattern, density and voids were adjusted in order to develop accurate deformation response. The deformation of the phantom cell was characterized and compared after impact testing with the actual lithium-ion cells. The experimental results were also compared with explicit simulations (LS-DYNA). This work shows progress toward an accurate and safe experimental procedure for structural impact testing on the entire battery pack consisting of thousands of volatile cells. Understanding battery and battery pack structural response can influence design and improve safety of electric vehicles.

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Liu, Yanzhen, Sutuke Yibulayimu, Zhibin Sun, Yuneng Wang, Yu Wang e Facheng Li. "Design of Novel Adipose Tissue Mimicking Phantom Material for Liposuction Training". In 2021 14th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics (CISP-BMEI). IEEE, 2021. http://dx.doi.org/10.1109/cisp-bmei53629.2021.9624375.

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Beblo, Richard V., e Lisa Mauck Weiland. "Using Multiscale Modeling to Predict Material Response of Polymeric Materials". In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1333.

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Presented is a multiscale modeling method applied to light activated shape memory polymers (LASMP). LASMP are a new class of shape memory polymer (SMP) being developed for applications where a thermal stimulus is undesired. Rotational Isomeric State (RIS) theory is used to build a molecular scale model of the polymer chain yielding a list of distances between the predicted cross-link locations, or r-values. The r-values are then fit with Johnson probability density functions and used with Boltzmann statistical mechanics to predict stress as a function of strain of the phantom network. Junction constraint theory is then used to calculate the stress contribution due to interactions with neighboring chains, resulting in previously unattainable numerically accurate Young’s modulus predictions based on the molecular formula of the polymer. The system is modular in nature and thus lends itself well to being adapted for specific applications. The results of the model are presented with experimental data for confirmation of correctness along with discussion of the potential of the model to be used to computationally adjust the chemical composition of LASMP to achieve specified material characteristics, greatly reducing the time and resources required for formula development.

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Lee, Jungyub, Juhyang Lee, Kihong Min, Yonghun Cheon e Seungkee Yang. "Reducing effects of hand phantom on mobile antennas using magneto-dielectric material". In 2013 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting. IEEE, 2013. http://dx.doi.org/10.1109/aps.2013.6710918.

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Morscher, Stefan, e James Joseph. "International photoacoustic standardisation consortium (IPASC): evolving a standardized PA phantom material composition". In Photons Plus Ultrasound: Imaging and Sensing 2021, a cura di Alexander A. Oraevsky e Lihong V. Wang. SPIE, 2021. http://dx.doi.org/10.1117/12.2578287.

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Bussod, S., J. F. P. J. Abascal, N. Ducros, C. Olivier, S. Si-Mohamed, P. Douek, C. Chappard e F. Peyrin. "Human Knee Phantom for Spectral CT: Validation of a Material Decomposition Algorithm". In 2019 IEEE 16th International Symposium on Biomedical Imaging (ISBI). IEEE, 2019. http://dx.doi.org/10.1109/isbi.2019.8759192.

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Prokhorova, Alexandra, Sebastian Ley, Ondrej Fiser, Jan Vrba, Jurgen Sachs e Marko Helbig. "Temperature Dependent Dielectric Properties of Tissue Mimicking Phantom Material in the Microwave Frequency Range". In 2020 14th European Conference on Antennas and Propagation (EuCAP). IEEE, 2020. http://dx.doi.org/10.23919/eucap48036.2020.9135466.

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