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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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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.
Testo completoAbstract (sommario):
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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Teixeira, Ana M., e Pedro Martins. "Mechanical characterisation of an organic phantom candidate for breast tissue". Journal of Biomaterials Applications 34, n. 8 (26 dicembre 2019): 1163–70. http://dx.doi.org/10.1177/0885328219895738.
Testo completoAbstract (sommario):
The aim of this study is to analyse the mechanical properties of agarose, which can be used as a mechanical phantom for breast tissues. In general, tissue mimicking materials may be used to achieve a better understanding of the structure and properties of tissues and organs; this work shares these objectives. The phantom can be used as a tissue surrogate with realistic mechanical behaviour for biomechanical applications. To validate agarose as a suitable mechanical phantom for breast tissues, indentation tests were performed in homogeneous, rectangular agarose blocks. Blocks with different agarose concentrations were moulded and tested. An estimation of the material stiffness was then compared with experimental data on different breast tissues’ types found in literature. The phantom stiffness increased consistently with agarose concentration and stress. The results show that agarose-based mechanical phantoms of stiffer tissues require higher agarose concentrations (0.5% and 0.6%). In contrast, normal tissues can be mimicked with 0.3% and 0.4% of agarose. In addition, it was observed that preconditioning affects the mechanical properties of the gel, as it had already been shown in literature for breast tissues.
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Rennoll, Valerie, Ian McLane, Mounya Elhilali e James E. West. "Optimized Acoustic Phantom Design for Characterizing Body Sound Sensors". Sensors 22, n. 23 (23 novembre 2022): 9086. http://dx.doi.org/10.3390/s22239086.
Testo completoAbstract (sommario):
Many commercial and prototype devices are available for capturing body sounds that provide important information on the health of the lungs and heart; however, a standardized method to characterize and compare these devices is not agreed upon. Acoustic phantoms are commonly used because they generate repeatable sounds that couple to devices using a material layer that mimics the characteristics of skin. While multiple acoustic phantoms have been presented in literature, it is unclear how design elements, such as the driver type and coupling layer, impact the acoustical characteristics of the phantom and, therefore, the device being measured. Here, a design of experiments approach is used to compare the frequency responses of various phantom constructions. An acoustic phantom that uses a loudspeaker to generate sound and excite a gelatin layer supported by a grid is determined to have a flatter and more uniform frequency response than other possible designs with a sound exciter and plate support. When measured on an optimal acoustic phantom, three devices are shown to have more consistent measurements with added weight and differing positions compared to a non-optimal phantom. Overall, the statistical models developed here provide greater insight into acoustic phantom design for improved device characterization.
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Hütter, Larissa, Patrick H. Geoghegan, Paul D. Docherty, Milad S. Lazarjan, Donald Clucas e Mark Jermy. "Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation". Current Directions in Biomedical Engineering 2, n. 1 (1 settembre 2016): 493–97. http://dx.doi.org/10.1515/cdbme-2016-0109.
Testo completoAbstract (sommario):
AbstractCompliant phantoms of the human aortic arch can mimic patient specific cardiovascular dysfunctions in vitro. Hence, phantoms may enable elucidation of haemodynamic disturbances caused by aortic dysfunction. This paper describes the fabrication of a thin-walled silicone phantom of the human ascending aorta and brachiocephalic artery. The model geometry was determined via a meta-analysis and modelled in SolidWorks before 3D printing. The solid model surface was smoothed and scanned with a 3D scanner. An offset outer mould was milled from Ebalta S-Model board. The final phantom indicated that ABS was a suitable material for the internal model, the Ebalta S-Model board yielded a rough external surface. Co-location of the moulds during silicone pour was insufficient to enable consistent wall thickness. The resulting phantom was free of air bubbles but did not have the desired wall thickness consistency.
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Paulsen, Samantha J., Trevor M. Mitcham, Charlene S. Pan, James Long, Bagrat Grigoryan, Daniel W. Sazer, Collin J. Harlan et al. "Projection-based stereolithography for direct 3D printing of heterogeneous ultrasound phantoms". PLOS ONE 16, n. 12 (9 dicembre 2021): e0260737. http://dx.doi.org/10.1371/journal.pone.0260737.
Testo completoAbstract (sommario):
Modern ultrasound (US) imaging is increasing its clinical impact, particularly with the introduction of US-based quantitative imaging biomarkers. Continued development and validation of such novel imaging approaches requires imaging phantoms that recapitulate the underlying anatomy and pathology of interest. However, current US phantom designs are generally too simplistic to emulate the structure and variability of the human body. Therefore, there is a need to create a platform that is capable of generating well-characterized phantoms that can mimic the basic anatomical, functional, and mechanical properties of native tissues and pathologies. Using a 3D-printing technique based on stereolithography, we fabricated US phantoms using soft materials in a single fabrication session, without the need for material casting or back-filling. With this technique, we induced variable levels of stable US backscatter in our printed materials in anatomically relevant 3D patterns. Additionally, we controlled phantom stiffness from 7 to >120 kPa at the voxel level to generate isotropic and anisotropic phantoms for elasticity imaging. Lastly, we demonstrated the fabrication of channels with diameters as small as 60 micrometers and with complex geometry (e.g., tortuosity) capable of supporting blood-mimicking fluid flow. Collectively, these results show that projection-based stereolithography allows for customizable fabrication of complex US phantoms.
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Ansar, Asnaeni, Dahlang Tahir, Bualkar Abdullah, Nurhasmi, Siti Fatimah e Jusmawang. "Physical Characteristics of Soft Tissue Phantom from Silicone Rubber Based Vulcanization System". Materials Science Forum 966 (agosto 2019): 194–99. http://dx.doi.org/10.4028/www.scientific.net/msf.966.194.
Testo completoAbstract (sommario):
Phantom from silicone rubber base material has been synthesized without glycerin and with additional glycerin of 10%, 20%, 30% and 40%. The type of Silicone rubber used is Room Temperature Vulcanized (RTV) 52 with a vulcanization system at room temperature. The concentration of catalyst is 5% from silicone rubber. Sample has characterized by using physical testing, Fourier Transform Infra Red (FTIR) and elastic modulus measurements. Physical testing result shows that phantoms have low degradation and can be applicated in a long time. FTIR data shows a phantom structure is poly (dimethylsiloxane) that has Si-CH3 bond at wavenumber 1261 cm-1 and 802 cm-1 and the Si-O-Si siloxane group at wavenumber 1024 cm-1. The elastic modulus values of phantom are 244 kPa for without glycerin, 210 kPa for 10% glycerin and 126 kPa for 20% glycerin. From the data indicated phantoms has range of the liver elastic modulus value at 0.6-4000 kPa. It means that phantom can be used as a substitute for the soft tissue of the human liver.
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Lee, Jin-Soo, Yong-In Jo, Yeong-Rok Kang, Yong-Uk Kye, Park Il e Dong-Yeon Lee. "Filament material evaluation for breast phantom fabrication using three-dimensional printing". Nuclear Technology and Radiation Protection 35, n. 4 (2020): 372–79. http://dx.doi.org/10.2298/ntrp2004372l.
Testo completoAbstract (sommario):
In this study, a method of directly evaluating the dose received by the highly radiation-sensitive mammary gland during mammography was investigated, and a corresponding breast phantom was produced that expresses a mammary gland, as an alternative to the existing mixed-form phantom. After designing this breast phantom by performing Monte Carlo simulations, the glandular dose was evaluated and compared with that of a mixed-form phantom. Then, dose evaluation was conducted for current commercial filament materials that could be used to fabricate the phantom by 3-D printing. The results showed that the dose received by the mammary gland was in the range of 1.089-1.237 mGy, and the average difference from that determined using the mixed-form phantom was approximately 1.2 %. Among the filament materials, polylactic acid showed the dose that was the most similar to that of the mammary gland tissue, differing by approximately 2.4 %. Overall, the research results suggest that it is meaningful to evaluate the glandular dose using the developed phantom instead of a mixed-form phantom. Besides, polylactic acid is the most appropriate material for fabricating the mammary gland tissue using a 3-D printer.
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Tseghai, Granch Berhe, Benny Malengier, Kinde Anlay Fante e Lieva Van Langenhove. "A Long-Lasting Textile-Based Anatomically Realistic Head Phantom for Validation of EEG Electrodes". Sensors 21, n. 14 (7 luglio 2021): 4658. http://dx.doi.org/10.3390/s21144658.
Testo completoAbstract (sommario):
During the development of new electroencephalography electrodes, it is important to surpass the validation process. However, maintaining the human mind in a constant state is impossible which in turn makes the validation process very difficult. Besides, it is also extremely difficult to identify noise and signals as the input signals are not known. For that reason, many researchers have developed head phantoms predominantly from ballistic gelatin. Gelatin-based material can be used in phantom applications, but unfortunately, this type of phantom has a short lifespan and is relatively heavyweight. Therefore, this article explores a long-lasting and lightweight (−91.17%) textile-based anatomically realistic head phantom that provides comparable functional performance to a gelatin-based head phantom. The result proved that the textile-based head phantom can accurately mimic body-electrode frequency responses which make it suitable for the controlled validation of new electrodes. The signal-to-noise ratio (SNR) of the textile-based head phantom was found to be significantly better than the ballistic gelatin-based head providing a 15.95 dB ± 1.666 (±10.45%) SNR at a 95% confidence interval.
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Watanabe, Yoichi, Divyajot Sandhu, Leighton Warmington, Sean Moen e Ramachandra Tummala. "Three-dimensional assessment of the effects of high-density embolization material on the absorbed dose in the target for Gamma Knife radiosurgery of arteriovenous malformations". Journal of Neurosurgery 125, Supplement_1 (dicembre 2016): 123–28. http://dx.doi.org/10.3171/2016.7.gks161545.
Testo completoAbstract (sommario):
OBJECTIVEArteriovenous malformation (AVM) is an intracranial vascular disorder. Gamma Knife radiosurgery (GKRS) is used in conjunction with intraarterial embolization to eradicate the nidus of AVMs. Clinical results indicate that patients with prior embolization tend to gain less benefit from GKRS. The authors hypothesized that this was partly caused by dosimetric deficiency. The actual dose delivered to the target may be smaller than the intended dose because of increased photon attenuation by high-density embolic materials. The authors performed a phantom-based study to quantitatively evaluate the 3D dosimetric effect of embolic material on GKRS.METHODSA 16-cm-diameter and 12-cm-long cylindrical phantom with a 16-cm-diameter hemispherical dome was printed by a 3D printer. The phantom was filled with radiologically tissue-equivalent polymer gel. To simulate AVM treatment with embolization, phantoms contained Onyx 18. The material was injected into an AVM model, which was suspended in the polymer gel. The phantom was attached to a Leksell frame by standard GK fixation method, using aluminum screws, for imaging. The phantom was scanned by a Phillips CT scanner with the standard axial-scanning protocol (120 kV and 1.5-mm slice thickness). CT-based treatment planning was performed with the GammaPlan treatment planning system (version 10.1.1). The plan was created to cover a fictitious AVM target volume near the embolization areas with eleven 8-mm shots and a prescription dose of 20 Gy to 50% isodose level. Dose distributions were computed using both tissue maximum ratio (TMR) 10 and convolution dose-calculation algorithms. These two 3D dose distributions were compared using an in-house program. Additionally, the same analysis method was applied to evaluate the dosimetric effects for 2 patients previously treated by GKRS.RESULTSThe phantom-based analyses showed that the mean dose difference between TMR 10 and convolution doses of the AVM target was no larger than 6%. The difference for GKRS cases was 5%. There were small areas where a large dose difference was observed on the isodose line plots, and those differences were mostly at or in the vicinity of the embolization materials.CONCLUSIONSThe results of both the phantom and patient studies showed a dose reduction no larger than 5% due to the embolization material placed near the target. Although the comparison of 3D dose distributions indicated small local effects of the embolic material, the clinical impact on the obliteration rate is expected to be small.
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Passariello, Fausto. "Non-animal ultrasound phantoms for device testing and training". Journal of Theoretical and Applied Vascular Research 2, n. 3 (30 giugno 2018): 119–21. http://dx.doi.org/10.24019/jtavr.26.
Testo completoAbstract (sommario):
A phantom is a physical object to simplify device testing and clinical training. An industrial device is more reliable for device testing in quality control procedures, though it is expensive. When precision requirements are not so strict as it occurs in training, people prefer to use home-made phantoms, though many of these artisanal methods use animal products. The current paper illustrates a few alternative vegetal phantoms. Agar is a widely used material in laboratory investigations and can be used to contain ultrasound targets. Another quick and effective alternative is given by tofu. Target sizes and flow ultrasound measurements can be easily effected using a phantom and training can be planned and repeated as much as required. The current paper shows how low-cost animal phantoms can be perfectly replaced by low-cost vegetal ones for clinical and training purposes. Vegetal phantoms can be classified as possible realizations of the Replace, the 1st of the 3Rs pre-requisites for non-animal experiments.
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Inal, Aysun. "Dosimetric evaluation of two phases of respiratory movement using a lung equivalent material for radiotherapy treatment planning". Journal of Radiotherapy in Practice 19, n. 2 (18 luglio 2019): 157–62. http://dx.doi.org/10.1017/s1460396919000505.
Testo completoAbstract (sommario):
AbstractBackground/aim:Radiation dosimetry requires special phantoms which are comparable with organs and tissues of a human body. The lung is one of the organs with a low density. Therefore, it is important to create and use lung equivalent phantoms in dosimetric controls. The aim of this study was to investigate the importance of using lung equivalent phantoms for different respiratory phases during measurements with both computed tomography (CT) and linear accelerator.Materials and methods:The maximum lung inhalation phantom (LIP) and lung exhalation phantom (LEP) were created for two respiratory phases. The Hounsfield Unit (HU) values based on the selected slice thickness and CT tube voltages were investigated, as well as the difference between energy and algorithms used in the treatment planning system.Results:It was found that the change in HU values according to slice thickness were more significant in measurements for respiratory phases. The dose difference between LEP and LIP at a point which is located 1 cm below the surface of the phantoms was found as 1·0% for 6 megavolt (MV) and 2·8% for 18 MV. The highest difference between the two algorithms was found to be 7·22% for 6 MV and 10·93% for 18 MV for LIP phantom.Conclusion:It can be said that the LIP and LEP phantoms prepared in accordance with respiratory phases can be a simple and inexpensive method to investigate any difference in dosimetry during respiratory phases. Also, measured and calculated dose values are in good agreement when thinner slice thickness was chosen.
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Boote, Evan J., James A. Zagzebski, Ernest L. Madsen e Timothy J. Hall. "Instrument-Independent Acoustic Backscatter Coefficient Imaging". Ultrasonic Imaging 10, n. 2 (aprile 1988): 121–38. http://dx.doi.org/10.1177/016173468801000204.
Testo completoAbstract (sommario):
This paper presents an adaptation of a method for determining acoustic backscatter coefficients to produce quantitative ultrasound images. Backscattered echo signals are recorded from a region to be imaged and backscatter coefficients are determined and related to spatial position. The values of the backscatter coefficients are then translated into a gray scale image. Testing of this imaging technique has been performed using tissue-mimicking phantoms which contain sections having backscatter coefficients different from that of the surrounding material. The technique has also been tested using a phantom in which a fat-mimicking layer is interposed between the acoustic window and the main body of the phantom. The images produced were found to be quantitatively accurate throughout the phantom, including the sections with differing backscatter. Quantitative accuracy did not suffer when the fat-mimicking layer was present.
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Mendes, Carlos, e Custódio Peixeiro. "Fabrication, Measurement and Time Decay of the Electromagnetic Properties of Semi-Solid Water-Based Phantoms". Sensors 19, n. 19 (4 ottobre 2019): 4298. http://dx.doi.org/10.3390/s19194298.
Testo completoAbstract (sommario):
This paper presents a complete and detailed description of the fabrication and measurement of the electromagnetic properties of water-based semi-solid phantoms with emphasis on the analysis of the time evolution of the complex permittivity of several samples stored in different conditions. A known recipe for a 2/3 muscle equivalent phantom is used as test material, and the several phantom sample properties are measured with an in-house developed coaxial probe technique. It is shown that the storing condition is of paramount importance to extend the lifetime of a given phantom. This behavior stems from the way the storing condition affects the water evaporation rate of the sample. In particular, while an unprotected sample can preserve its electromagnetic properties only for a few days, a very well-sealed one can last at least up to a year.
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Hariyanto, Aditya Prayugo, Kurnia Hastu Christianti, Agus Rubiyanto, Nasori Nasori, Mohammad Haekal e Endarko Endarko. "The Effect of Pattern and Infill Percentage in 3D Printer for Phantom Radiation Applications". Jurnal ILMU DASAR 23, n. 2 (27 luglio 2022): 87. http://dx.doi.org/10.19184/jid.v23i2.27256.
Testo completoAbstract (sommario):
3D printing technology was capable of fabricating phantoms to enhance quality assurance in radiation therapy. The ideal phantom has properties equivalent to the real tissue. However, 3D Printing has the limits to mimicking the attenuation properties of various tissues because during 3D printing there can be only one type of material. The purpose of this study was to evaluate the effect of infill percentage and infill patterns of 3D printing technology to simulate various types of tissue. This study used 25 samples measuring 5 × 5 × 1 cm3 from PETG material. The 20 samples were printed using variations infill percentages from 5 - 100% and the infill pattern in lines. The five samples were then printed with the infill percentage constant at 50% and used the infill pattern triangles, grid, gyroid, octet, and concentric. We used Computed Tomography (CT) to determine the Hounsfield Unit (HU) value for each sample and evaluated the suitability of each sample for phantom applications in radiation therapy and radiology. However, none of the samples was able to simulate compact bone. As a result, we found that PETG material could simulate the properties of soft tissue, fat, lung, kidney, liver, pancreas, and spongy bone. Thus, the study had shown promising potential for the fabrication of the anthropomorphic phantom of radiation therapy.
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Hoy, Carlton FO, Hani E. Naguib e Narinder Paul. "Fabrication and characterization of polymeric cellular foams for low-density computed tomography phantom applications". Journal of Cellular Plastics 55, n. 1 (24 ottobre 2018): 73–87. http://dx.doi.org/10.1177/0021955x18806833.
Testo completoAbstract (sommario):
Computed tomography imaging phantom devices have proven to be beneficial in improving computed tomography diagnostic techniques. Though commercial phantoms are available with tissue mimicking properties, there is a lack of low-density tissue specificity and variety. This study proposes a method for the fabrication of various low-density tissue mimicking computed tomography imaging phantoms. By illustrating the fabrication technique, material properties can be shown to be controlled and assessed against characteristic computed tomography imaging properties, most particularly, the computed tomography number in Hounsfield Units. A batch cellular foaming technique was utilized on thermoplastic polyurethane with ranging heated water bath foaming times from 0.5 to 10 min to fabricate polymeric computed tomography phantoms of controlled foam material properties. Computed tomography number values were experimentally measured. Additionally, separate experimental measurements were made on the foam characteristic properties of fabricated thermoplastic polyurethane foams. A relative decreasing trend was exhibited between the foam characteristic properties of cell density, average cell size, and material density to computed tomography number.
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Samson, Damilola Oluwafemi, Ahmad Shukri, Nurul Ab Aziz Hashikin, Siti Hajar Zuber, Mohd Zahri Abdul Aziz, Rokiah Hashim, Mohd Fahmi Mohd Yusof, Nor Ain Rabaiee e Sylvester Jande Gemanam. "Dosimetric Characterization of DSF/NaOH/IA-PAE/R. spp. Phantom Material for Radiation Therapy". Polymers 15, n. 1 (3 gennaio 2023): 244. http://dx.doi.org/10.3390/polym15010244.
Testo completoAbstract (sommario):
Background: Different compositions of DSF/NaOH/IA-PAE/R. spp. composite particleboard phantoms were constructed. Methods: Photon attenuation characteristics were ascertained using gamma rays from 137Cs and 60Co. Absorbed doses at the location of an ionization chamber and Gafchromic EBT3 radiochromic films were calculated for high-energy photons (6 and 10 MV) and electrons (6, 9, 12, and 15 MeV). Results: The calculated TPR20,10 values indicate that the percentage discrepancy for 6 and 10 MV was in the range of 0.29–0.72% and 0.26–0.65%. It was also found that the relative difference in the dmax to water and solid water phantoms was between 1.08–1.28% and 5.42–6.70%. The discrepancies in the determination of PDD curves with 6, 9, 12, and 15 MeV, and those of water and solid water phantoms, ranged from 2.40–4.84%. Comparable results were found using the EBT3 films with variations of 2.0–7.0% for 6 and 10 MV photons. Likewise, the discrepancies for 6, 9, 12, and 15 MeV electrons were within an acceptable range of 2.0–4.5%. Conclusions: On the basis of these findings, the DSF/NaOH/IA-PAE/R. spp. particleboard phantoms with 15 wt% IA-PAE addition level can be effectively used as alternative tissue-equivalent phantom material for radiation therapy applications.
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Shakhov, P. V., G. V. Tikhonowski, E. A. Popova-Kuznetsova, A. Yu Zakharkiv, E. V. Gromushkina, S. M. Klimentov e A. A. Popov. "Studying IR Photohyperthermia Sensitized by Titanium Nitride Nanoparticles Using Tissue-Equivalent Phantoms". Meditsinskaya Fizika 94, n. 2 (12 luglio 2022): 85–95. http://dx.doi.org/10.52775/1810-200x-2022-94-2-85-95.
Testo completoAbstract (sommario):
Purpose: To use tissue-equivalent phantom for studies of thermal fields in biological tissues during IR photo hyperthermia with plasmonic titanium nitride nanoparticles (TiN NPs). Material and methods: Gel phantom based on polyacrylamide (PAA) with addition of naphtol green dye and intralipid 10% was created. Optical properties (reduced scattering coefficient) of phantom ingredients were determined using added absorber technique. Thermal field distribution was studied with IR thermal imaging technique. 50 nm plasmonic TiN NPs, synthetized by laser ablation in liquids, were used as sensitizers of photothermic action. Photothermal experiments were performed using two phantoms: a phantom with homogeneous optical parameters, which are relevant to biological tissues (absorption coefficient µa=0.35 сm-1, reduced scattering coefficient µ's=30 сm-1), and a phantom containing 0.02 mg/ml of TiN NPs, which increased absorption coefficient by Dµa=0.65 сm-1. The part of phantom with the NPs was located under 5 mm layer of NPs-free phantom. Photothermal effect was excited by CW laser irradiation of 830 nm wavelength and 16 W/cm2 intensity (900 mW, beam diameter: 1.3 mm) for 2 min. Thermal field distribution inside the phantom was measured by IR thermal camera. Results: A tissue-equivalent gel phantom with independently tunable absorption and scattering coefficients was designed. The phantom had cubic shape with 30 30 30 mm size. Results of photothermal experiments showed that the use of TiN NPs as sensitizers IR photohyperthermia leads to a significant increase in tissue temperature (up to 5 degrees Celsius) at distances up to 15 mm under the phantom surface. In addition, a simple experimental setup for measuring scattering coefficient of a liquid phantom ingredients was described. Conclusion: A simple method for preparation of PAA phantom for modelling photothermal heating of biological tissues and studying thermal fields distributions was described. The phantom is handy and allows one to quickly experimentally simulate the photothermal response of biological tissues, including tissues containing various spatial distributions of photosensitive NPs. TiN NPs experimentally confirmed to be an effective sensitizer of IR photothermal effect.
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Fukuchi, T., S. Takeda, M. Katsuragawa, G. Yabu, S. Watanabe, T. Takahashi e Y. Watanabe. "Gamma-ray computed tomography system with a double-sided strip detector". Journal of Instrumentation 18, n. 01 (1 gennaio 2023): P01030. http://dx.doi.org/10.1088/1748-0221/18/01/p01030.
Testo completoAbstract (sommario):
Abstract We have developed a γ-ray computed tomography system using a CdTe double-sided strip detector. Owing to a 250 μm fine strip pitch and high energy resolution with photon-counting capability, the system provides highly accurate images, with which the materials and their distributions inside the target can be determined according to the photon transmittances. We evaluated the key performance of the system, conducting transmission measurements for Al, Cu, and Pb plates and also for Al, Fe, Cu, and Pb rod-phantoms, both using X-rays (∼30 keV) and γ-rays (∼80 keV) from a 133Ba source. The measured transmittances agreed well with the calculated values from simulations. We successfully reconstructed the three-dimensional structure of the rod-phantom and distinguished the elements inside the phantom. Compared with the simulated photon transmittances, we found that material identification based on tomographic images obtained with the system is efficient as long as the target object does not contain thick high-Z elements.
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Tins, Bernhard, e Jan Herman Kuiper. "Building an orthopaedic CT phantom for under £50". British Journal of Radiology 92, n. 1094 (febbraio 2019): 20180279. http://dx.doi.org/10.1259/bjr.20180279.
Testo completoAbstract (sommario):
Objective: In procuring a CT scanner for orthopaedic imaging, the ability of the scanner to cope with metal artefacts for visualising bone and bone lesions around orthopaedic implants is an important feature. A durable and easily transportable CT phantom would help to compare this feature between CT scanners.The aims of this study were to develop a CT phantom that is easy to build, easily transportable, stable over time, cheap and challenging CT scanner performance. Methods: A CT phantom resembling a femur and tibia with a total knee replacement was constructed from spare components of a knee replacement, wall filler and polystyrene. A number of plastic strips and cylinders were placed between metal implant and bone substitute during construction to act as “bone lesions”. The phantom was fixed in a watertight acrylic box with epoxy resin. Results: The total manufacturing time was below 3 h staggered over several days and the total cost was below £50. When empty, the phantom is easily transportable. The box can be filled with water on site visits ensuring a reproducible attenuation. This phantom is stable (i.e. not affected by decay of biological tissue). Conclusion: The phantom was easy to construct and is well transportable and stable in time. The phantom can be used in a procurement process allowing direct comparison of different scanners regarding technical factors and software performance. It can further be used for quality assurance, scan parameter optimisation and research. We conclude that a simple and transportable CT phantom can be built using few resources that allows to compare CT scanners with respect to their ability to visualise bone lesions around metal implants. Advances in knowledge: It is possible to build a CT knee replacement phantom in a few hours and for less than £50. Other than the total knee implant, this CT phantom can be built with material available from any DIY store and simple tools. This CT phantoms allows objective comparisons in CT procurement. This CT phantom allows objective assessment of imaging protocols for clinical practice.
29
Lu, Z. F., J. A. Zagzebski, E. L. Madsen e F. Dong. "A Method for Estimating an Overlying Layer Correction in Quantitative Ultrasound Imaging". Ultrasonic Imaging 17, n. 4 (ottobre 1995): 269–90. http://dx.doi.org/10.1177/016173469501700402.
Testo completoAbstract (sommario):
A new method is tested to compensate for attenuation losses through the intervening layers in quantitative ultrasound imaging. The method subtracts the echo signal power spectrum acquired from a uniform region beneath the overlying layers from the signal power spectrum obtained from a reference phantom using the same instrumentation system settings. Changes in spectral components with frequency are then used to estimate the attenuation of the overlying layers. Several phantoms were used to test the method, among which was a phantom having three windows, one with no overlying layers and the other two with fat and muscle mimicking layers of different degrees of irregularity. Attenuation losses through the windows were compensated for using the technique, producing backscatter estimator images of a simulated tumor inside the phantom. After applying the method, consistent results for the backscatter estimator of the tumor, as well as the backscatter coefficient of the background material, were obtained from the various windows.
30
Kraft, K. A., P. P. Fatouros, G. D. Clarke e P. R. S. Kishore. "An MRI phantom material for quantitative relaxometry". Magnetic Resonance in Medicine 5, n. 6 (dicembre 1987): 555–62. http://dx.doi.org/10.1002/mrm.1910050606.
Testo completo
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Neidhardt, M., J. Ohlsen, N. Hoffmann e A. Schlaefer. "Parameter Identification for Ultrasound Shear Wave Elastography Simulation". Current Directions in Biomedical Engineering 7, n. 1 (1 agosto 2021): 35–38. http://dx.doi.org/10.1515/cdbme-2021-1008.
Testo completoAbstract (sommario):
Abstract Elasticity of soft tissue is a valuable information to physicians in treatment and diagnosis of diseases. The elastic properties of tissue can be estimated with ultrasound (US) shear wave imaging (SWEI). In US-SWEI, a force push is applied inside the tissue and the resulting shear wave is detected by high-frequency imaging. The properties of the wave such as the shear wave velocity can be mapped to tissue elasticity. Commonly, wave features are extracted by tracking the peak of the shear wave, estimating the phase velocity or with machine learning methods. To tune and test these methods, often simulation data is employed since material properties and excitation can be accurately controlled. Subsequent validation on real US-SWEI data is in many cases performed on tissue phantoms such as gelatine. Clearly, validation performance of these procedures is dependent on the accuracy of the simulated tissue phantom and a thorough comparison of simulation and experimental data is needed. In this work, we estimate wave parameters from 400 US-SWEI data sets acquired in various homogeneous gelatine phantoms. We tune a linear material model to these parameters. We report an absolute percentage error for the shear wave velocity between simulation and phantom experiment of <2.5%. We validate our material model on unknown gelatine concentrations and estimate the shear wave velocity with an error <3.4% for in-range concentrations indicating that our material model is in good agreement with US-SWEI measurements.
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de Korte, C. L., E. I. Céspedes, A. F. W. van der Steen, B. Norder e K. te Nijenhuis. "Elastic and Acoustic Properties of Vessel Mimicking Material for Elasticity Imaging". Ultrasonic Imaging 19, n. 2 (aprile 1997): 112–26. http://dx.doi.org/10.1177/016173469701900202.
Testo completoAbstract (sommario):
The mechanical and acoustic properties of agar-gelatin gels, used to construct vessel mimicking phantoms for ultrasonic elasticity studies, were investigated. Gels with varying compression moduli were made using a gelatin solution (8% by weight) with a variable amount of agar(1%-3% by weight). Carborundum particles were added as scattering material. The compression modulus was determined using a dynamic mechanical analyzer. The dependence of the compression modulus and the acoustic parameters on the agar concentration, as well as on the age and the temperature of the samples, was investigated. The results show that the compression modulus is strongly influenced by these factors, while the effect on the acoustic parameters is less. Compression moduli spanning a useful range for vascular phantom construction with realistic acoustic parameters can be achieved by varying the amount of agar. Phantoms constructed from these gels are well suited to serve as a model for plaque containing vessels.
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Monzari, Shaghayegh F., Ghazale Geraily, Tahereh Hadisi nia, Soraya Salmanian, Heydar Toolee e Mostafa Farzin. "Fabrication of anthropomorphic phantoms for use in total body irradiations studies". Journal of Radiotherapy in Practice 19, n. 3 (7 ottobre 2019): 242–47. http://dx.doi.org/10.1017/s1460396919000591.
Testo completoAbstract (sommario):
AbstractPurpose:The aim of this study was to produce a low-cost anatomical model of adult male including lower limbs to evaluate the three-dimensional dose distribution for dosimetry measurements, especially in total body irradiation (TBI) and total skin electron therapy (TSET).Materials and methods:Computed tomography (CT) scan images of the atomic energy organisation RANDO phantom and lower limb CT scan images of 20 healthy persons were averaged. Selections of different body tissues substitute materials and phantom validation were performed according to previous studies worked on construction of radiation therapy phantoms.Results:The dosimetry aspect of the selected substitute materials from all considered methods showed that they were in good agreement with real human tissue, especially bone, with a percentage error of 0·5%. The results show that the electron densities obtained from the linear attenuation coefficient (reDLAC) for the tissue equivalent material used in the phantom is a better option for validation.Conclusions:This validated phantom has numerous advantages over the origin type of RANDO phantom. Therefore, using it in TBI and TSET dosimetry is recommendable.
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Fiser, Ondrej, Sebastian Ley, Marko Helbig, Jürgen Sachs, Michaela Kantova e Jan Vrba. "Temperature dependent dielectric spectroscopy of muscle tissue phantom". International Journal of Microwave and Wireless Technologies 12, n. 9 (19 marzo 2020): 885–91. http://dx.doi.org/10.1017/s1759078720000203.
Testo completoAbstract (sommario):
AbstractThe temperature dependence of the dielectric parameters of tissues and tissue-mimicking phantoms is very important for non-invasive temperature measurement in medical applications using microwaves. We performed measurements of this dependence in the temperature range of 25–50°C using distilled water as a reference liquid commonly used in dielectric property studies. The results were compared with the literature model in the frequency range of 150–3000 MHz. Using this method, the temperature dependence of dielectric parameters of a new muscle tissue-mimicking phantom based on agar, polyethylene powder, and polysaccharide material TX-151 was measured in the temperature range of 25–50°C. The temperature dependence of the dielectric properties of this new muscle phantom was fitted to that of the two-pole Cole–Cole model and the deviation of the results between measured and modeled data was quantified.
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Dukov, Nikolay, Kristina Bliznakova, Nikiforos Okkalidis, Tsvetelina Teneva, Elitsa Encheva e Zhivko Bliznakov. "Thermoplastic 3D printing technology using a single filament for producing realistic patient-derived breast models". Physics in Medicine & Biology 67, n. 4 (10 febbraio 2022): 045008. http://dx.doi.org/10.1088/1361-6560/ac4c30.
Testo completoAbstract (sommario):
Abstract Objective. This work describes an approach for producing physical anthropomorphic breast phantoms from clinical patient data using three-dimensional (3D) fused-deposition modelling (FDM) printing. Approach. The source of the anthropomorphic model was a clinical Magnetic Resonance Imaging (MRI) patient image set, which was segmented slice by slice into adipose and glandular tissues, skin and tumour formations; thus obtaining a four component computational breast model. The segmented tissues were mapped to specific Hounsfield Units (HU) values, which were derived from clinical breast Computed Tomography (CT) data. The obtained computational model was used as a template for producing a physical anthropomorphic breast phantom using 3D printing. FDM technology with only one polylactic acid filament was used. The physical breast phantom was scanned at Siemens SOMATOM Definition CT. Quantitative and qualitative evaluation were carried out to assess the clinical realism of CT slices of the physical breast phantom. Main results. The comparison between selected slices from the computational breast phantom and CT slices of the physical breast phantom shows similar visual x-ray appearance of the four breast tissue structures: adipose, glandular, tumour and skin. The results from the task-based evaluation, which involved three radiologists, showed a high degree of realistic clinical radiological appearance of the modelled breast components. Measured HU values of the printed structures are within the range of HU values used in the computational phantom. Moreover, measured physical parameters of the breast phantom, such as weight and linear dimensions, agreed very well with the corresponding ones of the computational breast model. Significance. The presented approach, based on a single FDM material, was found suitable for manufacturing of a physical breast phantom, which mimics well the 3D spatial distribution of the different breast tissues and their x-ray absorption properties. As such, it could be successfully exploited in advanced x-ray breast imaging research applications.
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Xie, Tianci, Bo He, Qieming Shi, Jinqian Qian, Wenjing Hao, Song Li, Elfed Lewis e Weimin Sun. "Measurement of scattered rays from different materials using an inorganic scintillator based optical fiber sensor and its application in radiotherapy". Biomedical Physics & Engineering Express 8, n. 2 (21 gennaio 2022): 025004. http://dx.doi.org/10.1088/2057-1976/ac48e3.
Testo completoAbstract (sommario):
Abstract Measurements using an Optical Fiber OFS including an inorganic scintillator placed on the surface of a phantom show that the particle energy distribution inside the phantom remains unchanged. The backscattered intensity measured using an Optical Fiber Sensor (OFS) exhibits a linear relationship with the total radiation dose delivered to the phantom, and this relationship shows that the OFS can be used for indirect dose measurement when located on the surface of the phantom i.e. that arising from the energetic backscattered electrons and photons. Such a device can therefore be used as a clinical in-vivo dosimeter, being located on the patient’s body surface. In addition, the measurement results for the same OFS located inside and outside the radiation field of a compound water based phantom are analyzed. The differences in measurement of the fluorescence signal in response to various tissue materials representing bone or tumor tissue in the irradiation field are strongly related to the material’s ability to block the scattered rays from the water phantom, as well as the scattered x-rays generated by the material located within the phantom.
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Chew, Kim Mey, Rubita Sudirman, Norhudah Seman e Ching Yee Yong. "Human Brain Phantom Modeling: Concentration and Temperature Effects on Relative Permittivity". Advanced Materials Research 646 (gennaio 2013): 191–96. http://dx.doi.org/10.4028/www.scientific.net/amr.646.191.
Testo completoAbstract (sommario):
This paper discusses on selecting the most appropriate material for developing human-like brain phantom. It aims to investigate the effect of concentration and temperature to relative permittivity of a sample. This phantom was developed as a human-like brain for tumour detection using microwave signal. Result shows that plant gelatine is a stable and appropriate material for building phantom than agar-agar. A few models were developed based on the proposed ratio of mixture.
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Radojcic, Đeni Smilovic, David Rajlic, Bozidar Casar, Manda Svabic Kolacio, Nevena Obajdin, Dario Faj e Slaven Jurkovic. "Evaluation of two-dimensional dose distributions for pre-treatment patient-specific IMRT dosimetry". Radiology and Oncology 52, n. 3 (30 aprile 2018): 346–52. http://dx.doi.org/10.2478/raon-2018-0019.
Testo completoAbstract (sommario):
Abstract Background The accuracy of dose calculation is crucial for success of the radiotherapy treatment. One of the methods that represent the current standard for patient-specific dosimetry is the evaluation of dose distributions measured with an ionization chamber array inside a homogeneous phantom using gamma method. Nevertheless, this method does not replicate the realistic conditions present when a patient is undergoing therapy. Therefore, to more accurately evaluate the treatment planning system (TPS) capabilities, gamma passing rates were examined for beams of different complexity passing through inhomogeneous phantoms. Materials and methods The research was performed using Siemens Oncor Expression linear accelerator, Siemens Somatom Open CT simulator and Elekta Monaco TPS. A 2D detector array was used to evaluate dose distribution accuracy in homogeneous, semi-anthropomorphic and anthropomorphic phantoms. Validation was based on gamma analysis with 3%/3mm and 2%/2mm criteria, respectively. Results Passing rates of the complex dose distributions degrade depending on the thickness of non-water equivalent material. They also depend on dose reporting mode used. It is observed that the passing rate decreases with plan complexity. Comparison of the data for all set-ups of semi-anthropomorphic and anthropomorphic phantoms shows that passing rates are higher in the anthropomorphic phantom. Conclusions Presented results raise a question of possible limits of dose distribution verification in assessment of plan delivery quality. Consequently, good results obtained using standard patient specific dosimetry methodology do not guarantee the accuracy of delivered dose distribution in real clinical cases.
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Khattak, M. A., Abdoulhdi A. Borhana, Lailatul Fitriyah A. Shafii e Rustam Khan. "MCNPX’S Water Equivalent Thickness Simulation of Material with Different Density via Proton Beam Irradiation". International Journal of Engineering & Technology 7, n. 4.35 (30 novembre 2018): 678. http://dx.doi.org/10.14419/ijet.v7i4.35.23088.
Testo completoAbstract (sommario):
The radiological thickness of materials and beam penetration range is often referred as the water equivalent thickness (WET). In the clinical application of radiotherapy it is mandatory to obtain a WET calculation with high accuracies to ensure the beam that penetrated the human tissues is capable to deliver high dose of radiation into the deep-rooted tumors and kill the malignant cancerous cell without any major damages to the healthy tissues. Nevertheless, the present method of calculation that is available needs either intensive numerical method or approximation techniques with unknown precision. Hence, the purpose of this research is to study the depth of proton beam irradiation penetration range of materials with arbitrary density & elemental composition and modeled the water equivalent thickness (WET) calculation by using the Monte Carlo N Particle Transport Code Extension (MCNPX). There are several type of material with different density that are utilize in this project which are water phantom (ρ =1.0 g cm-3), PMMA (ρ =1.19 g cm-3) aluminum (ρ = 2.70 g cm-3 lead (ρ =11.3g cm-3). The water phantom represent reference material whilst PMMA, Aluminum and Lead each represent low, medium and high density respectively. Based from the result produced in output file, Bragg curves for each material were reproduced, analyzed and compared with the Bragg curve of water phantom. The WET of water phantom was successfully modelled by using MCNPX. Apart from the short computing time, modelling WET via MCNPX was more efficient compare to analytical calculation
40
Mami-Zadeh, H., R. Solgi, J. F. Carrier e H. Ghadiri. "Material classification based on Dual-Energy Micro-CT images by the Gaussian mixture model." Journal of Instrumentation 17, n. 02 (1 febbraio 2022): P02001. http://dx.doi.org/10.1088/1748-0221/17/02/p02001.
Testo completoAbstract (sommario):
Abstract This study aimed to implement an unsupervised classification method through the Gaussian mixture model to classify different materials using the scatter diagram of the linear attenuation coefficients acquired from dual-energy micro-CT imaging. This method estimates each cluster's distribution parameters and performs classification based on the posterior probability with a pre-determined cluster number. Our studies on dual-energy images of a phantom showed that the distribution of linear attenuation coefficient of different materials on the scatter diagram has a Gaussian distribution, and clusters can be classified using model-based clustering. The result of this classification method is related to the actual materials in the phantom, where a specific cluster represents each material. This classification method can be potentially used when the clusters are overlapped and the material is separated with high accuracy.
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Olsen, J. B., A. Skretting e A. Widmark. "Assessment of image quality and total performance in norwegian mammography laboratories". Acta Radiologica 39, n. 5 (settembre 1998): 507–13. http://dx.doi.org/10.1080/02841859809172216.
Testo completoAbstract (sommario):
Purpose: to assess the image quality at different mammography laboratories Material and Methods: Two commercial mammographic test phantoms and one phantom based on excised mammary tissue were used in an assessment of the imaging chain and total performance at 45 Norwegian mammography laboratories. the breast-tissue phantom was used for a receiver operating characteristics (ROC) analysis. This was carried out by putting overlays with identifiable regions (some of which contained a cluster of simulated calcifications) on top of the mammary tissue, and then having a radiologist report the confidence of a finding for each region Results and Conclusion: the areas under the ROC curves were in general high. in nearly all the laboratories, performance was improved when a magnification technique was applied. There were wide variations among the laboratories in total performance as measured by the area under the ROC curve, and also in the physical parameters derived by means of the commercial phantoms. in general, a good ROC performance was associated with a good physical performance in the imaging chain
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Abd Rahman, Nurul Huda, Yoshihide Yamada e Muhammad Shakir Amin Nordin. "Analysis on the Effects of the Human Body on the Performance of Electro-Textile Antennas for Wearable Monitoring and Tracking Application". Materials 12, n. 10 (19 maggio 2019): 1636. http://dx.doi.org/10.3390/ma12101636.
Testo completoAbstract (sommario):
Previous works have shown that wearable antennas can operate ideally in free space; however, degradation in performance, specifically in terms of frequency shifts and efficiency was observed when an antenna structure was in close proximity to the human body. These issues have been highlighted many times yet, systematic and numerical analysis on how the dielectric characteristics may affect the technical behavior of the antenna has not been discussed in detail. In this paper, a wearable antenna, developed from a new electro-textile material has been designed, and the step-by-step manufacturing process is presented. Through analysis of the frequency detuning effect, the on-body behavior of the antenna is evaluated by focusing on quantifying the changes of its input impedance and near-field distribution caused by the presence of lossy dielectric material. When the antenna is attached to the top of the body fat phantom, there is an increase of 17% in impedance, followed by 19% for the muscle phantom and 20% for the blood phantom. These phenomena correlate with the electric field intensities (V/m) observed closely at the antenna through various layers of mediums (z-axis) and along antenna edges (y-axis), which have shown significant increments of 29.7% in fat, 35.3% in muscle and 36.1% in blood as compared to free space. This scenario has consequently shown that a significant amount of energy is absorbed in the phantoms instead of radiated to the air which has caused a substantial drop in efficiency and gain. Performance verification is also demonstrated by using a fabricated human muscle phantom, with a dielectric constant of 48, loss tangent of 0.29 and conductivity of 1.22 S/m.
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Muellensiefen, Mara, Bernhard Tins, Jan-Herman Kuiper, Marc-André Weber e Holger Krakowski-Roosen. "Development of a total hip replacement phantom for the assessment of CT-image quality". Acta Radiologica 61, n. 12 (9 marzo 2020): 1644–52. http://dx.doi.org/10.1177/0284185120907981.
Testo completoAbstract (sommario):
Background The quality of computed tomography (CT) imaging is important when used to judge the success of joint replacement surgery. Metal artefacts are a known source of error, typically compensated by noise reduction software. Purpose To develop a transportable and stable system for the assessment of image quality of bone lesions around orthopedic implants. Material and Methods The design and manufacture of a bone-implant-phantom is described, which is based on a calf acetabulum with surrounding pelvic bone structures. Bone lesions of several sizes were created in the acetabulum before implanting the cup of an uncemented hip prosthesis, which was fixed with a stainless-steel bone screw. Plastic strips were placed on a cobalt–chromium stemmed femoral component, simulating typical bone lesions around loosening or infected prostheses, before embedding the stem in material similar to bone and shaped like a femur. The head of the femoral component was then placed in the acetabular cup and CT scans were produced. Results It was possible to construct a durable CT hip phantom for quality assurance work. The usability of different materials and the choices made for the phantom are discussed. Conclusion It is possible to construct a durable joint implant phantom for quality assurance and scanner hardware and software assessment with limited resources. The phantom was successfully used in the assessment of the hardware and software performance of different CT scanners.
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Grewal, Parvind K., Majid Shokoufi, Jeff Liu, Krishnan Kalpagam e Kirpal S. Kohli. "Electrical characterization of bolus material as phantom for use in electrical impedance and computed tomography fusion imaging". Journal of Electrical Bioimpedance 5, n. 1 (8 agosto 2019): 34–39. http://dx.doi.org/10.5617/jeb.781.
Testo completoAbstract (sommario):
Abstract Phantoms are widely used in medical imaging to predict image quality prior to clinical imaging. This paper discusses the possible use of bolus material, as a conductivity phantom, for validation and interpretation of electrical impedance tomography (EIT) images. Bolus is commonly used in radiation therapy to mimic tissue. When irradiated, it has radiological characteristics similar to tissue. With increased research interest in CT/EIT fusion imaging there is a need to find a material which has both the absorption coefficient and electrical conductivity similar to biological tissues. In the present study the electrical properties, specifically resistivity, of various commercially available bolus materials were characterized by comparing their frequency response with that of in-vivo connective adipose tissue. It was determined that the resistivity of Gelatin Bolus is similar to in-vivo tissue in the frequency range 10 kHz to 1MHz and therefore has potential to be used in EIT/CT fusion imaging studies.
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Belmont, Barry, Robert E. Dodde e Albert J. Shih. "Impedance of tissue-mimicking phantom material under compression". Journal of Electrical Bioimpedance 4, n. 1 (28 luglio 2019): 2–12. http://dx.doi.org/10.5617/jeb.443.
Testo completoAbstract (sommario):
Abstract The bioimpedance of tissues under compression is a field in need of study. While biological tissues can become compressed in a myriad of ways, very few experiments have been conducted to describe the relationship between the passive electrical properties of a material (impedance/admittance) and its underlying mechanical properties (stress and strain) during deformation. Of the investigations that have been conducted, the exodus of fluid from samples under compression has been thought to be the cause of changes in impedance, though until now was not measured directly. Using a soft tissue-mimicking phantom material (tofu) whose passive electrical properties are a function of the conducting fluid held within its porous structure, we have shown that the mechanical behavior of a sample under compression can be measured through bioimpedance techniques.
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Sato, Fuminobu, Tatsuro Maekawa, Tomoki Sakiyama, Naoki Zushi, Kikuo Shimizu, Yushi Kato, Isao Murata, Takayoshi Yamamoto e Toshiyuki Iida. "Development of human hand phantom containing radiophotoluminescence material". Radiation Measurements 85 (febbraio 2016): 18–25. http://dx.doi.org/10.1016/j.radmeas.2015.12.006.
Testo completo
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Arenas, Maria Alejandra Ardila, Dirk Gutkelch, Olaf Kosch, Rüdiger Brühl, Frank Wiekhorst e Norbert Löwa. "Development of Phantoms for Multimodal Magnetic Resonance Imaging and Magnetic Particle Imaging". Polymers 14, n. 19 (20 settembre 2022): 3925. http://dx.doi.org/10.3390/polym14193925.
Testo completoAbstract (sommario):
Phantoms are crucial for the development of imaging techniques based on magnetic nanoparticles (MNP). They serve as test objects to simulate application scenarios but are also used for quality assurance and interlaboratory comparisons. Magnetic particle imaging (MPI) is excellent for specifically detecting magnetic nanoparticles (MNP) without any background signals. To obtain information about the surrounding soft tissue, MPI is often used in combination with magnetic resonance imaging (MRI). For such application scenarios, this poses a challenge for phantom fabrication, as they need to accommodate MNP as well as provide MR visibility. Recently, layer-by-layer fabrication of parts using Additive Manufacturing (AM) has emerged as a powerful tool for creating complex and patient-specific phantoms, but these are characterized by poor MR visibility of the AM material. We present the systematic screening of AM materials as candidates for multimodal MRI/MPI imaging. Of all investigated materials, silicone (Dreve, Biotec) exhibited the best properties with sufficient MR-signal performance and the lowest absorption of MNP at the interface of AM materials. With the help of AM and the selection of appropriate materials, we have been able to produce suitable MRI/MPI phantoms.
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Saini, Amit, V. P. Pandey, Avtar Singh e Pankaj Kumar. "Evaluating impact of medium variation on dose calculated through planning system in a low cost in-house phantom". Biomedical Physics & Engineering Express 8, n. 2 (22 febbraio 2022): 025022. http://dx.doi.org/10.1088/2057-1976/ac53bc.
Testo completoAbstract (sommario):
Abstract Purpose: In radiotherapy, accuracy in dose estimation of dose calculation methods is critical. The influence of deformity on radiation dose calculations derived by planning system is evaluated in present study. The goal of study was to create a low-cost inhomogeneous phantom for measuring absorbed dose using an Ionisation chamber and Gafchromic film, which was validated using treatment planning system (TPS) dose outcome. Methods:and Materials: The central axis dose calculations were computed using Pencil Beam Convolution algorithm (PBC), Collapsed Cone Convolution (CCC) and Monte Carlo (MC) algorithm in the Monaco treatment planning system using an In-house phantom (20 × 20 × 20cm3) made up of acrylic sheet containing water and inhomogeneous material wooden powder equivalent to lung. Phantom was scanned in Computed Tomography (CT) scanner and image set was sent to the planning workstation. The depth dose evaluations were performed using ionization chamber and Gafchromic film with same beam settings and monitor units in every setup. Following that, the calculated doses obtained from TPS and measured depth doses were compared. Results: The results was reported for photon energies 6MV, 10MV, 15MV, 6FFF and 10FFF at varying field sizes of 4 × 4 cm2, 5 × 5 cm2, 10 × 10 cm2, and 15 × 15 cm2. MC maximum dose variation predicted was 2.06% in 15MV of measured chamber dose and −2.06% of measured gafchromic film dose in 6MVFFF. CCC maximum dose variation predicted was 2.68% of measured chamber dose in 6MV and 3.31% of measured gafchromic film dose in 6MV whereas PB maximum dose variation predicted was −5.94% in 15MV of measured chamber dose and −11.6% of measured gafchromic film dose in 6MVFFF. Conclusion: Low-cost in-house phantoms can be utilised to assess point and planar doses during patient-specific quality assurance in centres that don’t have accessibility to phantoms due to the high cost of commercially available tools.
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Hunold, Alexander, Daniel Strohmeier, Patrique Fiedler e Jens Haueisen. "Head phantoms for electroencephalography and transcranial electric stimulation: a skull material study". Biomedical Engineering / Biomedizinische Technik 63, n. 6 (27 novembre 2018): 683–89. http://dx.doi.org/10.1515/bmt-2017-0069.
Testo completoAbstract (sommario):
Abstract Physical head phantoms allow the assessment of source reconstruction procedures in electroencephalography and electrical stimulation profiles during transcranial electric stimulation. Volume conduction in the head is strongly influenced by the skull, which represents the main conductivity barrier. Realistic modeling of its characteristics is thus important for phantom development. In the present study, we proposed plastic clay as a material for modeling the skull in phantoms. We analyzed five clay types varying in granularity and fractions of fire clay, each with firing temperatures from 550°C to 950°C. We investigated the conductivity of standardized clay samples when immersed in a 0.9% sodium chloride solution with time-resolved four-point impedance measurements. To test the reusability of the clay model, these measurements were repeated after cleaning the samples by rinsing in deionized water for 5 h. We found time-dependent impedance changes for approximately 5 min after immersion in the solution. Thereafter, the conductivities stabilized between 0.0716 S/m and 0.0224 S/m depending on clay type and firing temperatures. The reproducibility of the measurement results proved the effectiveness of the rinsing procedure. Clay provides formability, is permeable to ions, can be adjusted in conductivity value and is thus suitable for the skull modeling in phantoms.
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Clark, Peter J., Giuseppe Forte, Mark J. H. Simmons e E. Hugh Stitt. "Towards 3D-Electrical Capacitance Tomography for Interface Detection". Johnson Matthey Technology Review 60, n. 2 (1 aprile 2016): 164–75. http://dx.doi.org/10.1595/205651316x691537.
Testo completoAbstract (sommario):
The application of three-dimensional electrical capacitance tomography (3D-ECT) for the in situ monitoring of a hard boundary or interface has been investigated using imaged phantoms that simulate real-life processes. A cylinder-in-tube phantom manufactured from polyethylene (PE), a low di-electric and non-conductive material, was imaged using the linear back projection (LBP) algorithm with the larger tube immersed at varying intervals to test the ability of the technique to image interfaces axially through the sensor. The interface between PE and air is clearly imaged and correlates to the known tube penetration within the sensor. The cylinder phantom is imaged in the centre of the sensor; however, the reduction in measurement density towards the centre of the ECT sensor results in reduced accuracy. A thresholding method, previously applied to binary systems to improve the imaged accuracy of a hard boundary between two separate phases, has been applied to the 3D-ECT tomograms that represent the PE phantom. This approach has been shown to improve the accuracy of the acquired image of a cylinder of air within a non-conductive PE tube.