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Sample records for tissue-mimicking phantom materials

  1. Tissue mimicking materials for a multi-imaging modality prostate phantom

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    D'Souza, Warren D.; Madsen, Ernest L.; Unal, Orhan; Vigen, Karl K.; Frank, Gary R.; Thomadsen, Bruce R.

    2001-01-01

    Materials that simultaneously mimic soft tissue in vivo for magnetic resonance imaging (MRI), ultrasound (US), and computed tomography (CT) for use in a prostate phantom have been developed. Prostate and muscle mimicking materials contain water, agarose, lipid particles, protein, Cu ++ , EDTA, glass beads, and thimerosal (preservative). Fat was mimicked with safflower oil suffusing a random mesh (network) of polyurethane. Phantom material properties were measured at 22 deg. C. (22 deg. C is a typical room temperature at which phantoms are used.) The values of material properties should match, as well as possible, the values for tissues at body temperature, 37 deg. C. For MRI, the primary properties of interest are T1 and T2 relaxations times, for US they are the attenuation coefficient, propagation speed, and backscatter, and for CT, the x-ray attenuation. Considering the large number of parameters to be mimicked, rather good agreement was found with actual tissue values obtained from the literature. Using published values for prostate parenchyma, T1 and T2 at 37 deg. C and 40 MHz are estimated to be about 1100 and 98 ms, respectively. The CT number for in vivo prostate is estimated to be 45 HU (Hounsfield units). The prostate mimicking material has a T1 of 937 ms and a T2 of 88 ms at 22 deg. C and 40 MHz; the propagation speed and attenuation coefficient slope are 1540 m/s and 0.36 dB/cm/MHz, respectively, and the CT number of tissue mimicking prostate is 43 HU. Tissue mimicking (TM) muscle differs from TM prostate in the amount of dry weight agarose, Cu ++ , EDTA, and the quality and quantity of glass beads. The 18 μm glass beads used in TM muscle increase US backscatter and US attenuation; the presence of the beads also has some effect on T1 but no effect on T2. The composition of tissue-mimicking materials developed is such that different versions can be placed in direct contact with one another in a phantom with no long term change in US, MRI, or CT

  2. Paraffin-gel tissue-mimicking material for ultrasound-guided needle biopsy phantom.

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    Vieira, Sílvio L; Pavan, Theo Z; Junior, Jorge E; Carneiro, Antonio A O

    2013-12-01

    Paraffin-gel waxes have been investigated as new soft tissue-mimicking materials for ultrasound-guided breast biopsy training. Breast phantoms were produced with a broad range of acoustical properties. The speed of sound for the phantoms ranged from 1425.4 ± 0.6 to 1480.3 ± 1.7 m/s at room temperature. The attenuation coefficients were easily controlled between 0.32 ± 0.27 dB/cm and 2.04 ± 0.65 dB/cm at 7.5 MHz, depending on the amount of carnauba wax added to the base material. The materials do not suffer dehydration and provide adequate needle penetration, with a Young's storage modulus varying between 14.7 ± 0.2 kPa and 34.9 ± 0.3 kPa. The phantom background material possesses long-term stability and can be employed in a supine position without changes in geometry. These results indicate that paraffin-gel waxes may be promising materials for training radiologists in ultrasound biopsy procedures. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  3. Construction of a preclinical multimodality phantom using tissue-mimicking materials for quality assurance in tumor size measurement.

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    Lee, Yongsook C; Fullerton, Gary D; Goins, Beth A

    2013-07-29

    World Health Organization (WHO) and the Response Evaluation Criteria in Solid Tumors (RECIST) working groups advocated standardized criteria for radiologic assessment of solid tumors in response to anti-tumor drug therapy in the 1980s and 1990s, respectively. WHO criteria measure solid tumors in two-dimensions, whereas RECIST measurements use only one-dimension which is considered to be more reproducible (1, 2, 3,4,5). These criteria have been widely used as the only imaging biomarker approved by the United States Food and Drug Administration (FDA) (6). In order to measure tumor response to anti-tumor drugs on images with accuracy, therefore, a robust quality assurance (QA) procedures and corresponding QA phantom are needed. To address this need, the authors constructed a preclinical multimodality (for ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI)) phantom using tissue-mimicking (TM) materials based on the limited number of target lesions required by RECIST by revising a Gammex US commercial phantom (7). The Appendix in Lee et al. demonstrates the procedures of phantom fabrication (7). In this article, all protocols are introduced in a step-by-step fashion beginning with procedures for preparing the silicone molds for casting tumor-simulating test objects in the phantom, followed by preparation of TM materials for multimodality imaging, and finally construction of the preclinical multimodality QA phantom. The primary purpose of this paper is to provide the protocols to allow anyone interested in independently constructing a phantom for their own projects. QA procedures for tumor size measurement, and RECIST, WHO and volume measurement results of test objects made at multiple institutions using this QA phantom are shown in detail in Lee et al. (8).

  4. Toxicology Analysis of Tissue-Mimicking Phantom Made From Gelatin

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    Dolbashid, A. S.; Hamzah, N.; Zaman, W. S. W. K.; Mokhtar, M. S.

    2017-06-01

    Skin phantom mimics the biological skin tissues as it have the ability to respond to changes in its environment. The development of tissue-mimicking phantom could contributes towards the reduce usage of animal in cosmetics and pharmacokinetics. In this study, the skin phantoms made from gelatin were tested with four different commonly available cosmetic products to determine the toxicity of each substance. The four substances used were; mercury-based whitening face cream, carcinogenic liquid make-up foundation, paraben-based acne cleanser, and organic lip balm. Toxicity test were performed on all of the phantoms. For toxicity testing, topographical and electrophysiological changes of the phantoms were evaluated. The ability of each respective phantom to react with mild toxic substances and its electrical resistance were analysed in to determine the toxicity of all the phantom models. Four-electrode method along with custom made electrical impedance analyser was used to differentiate electrical resistance between intoxicated phantom and non-intoxicated phantom in this study. Electrical resistance values obtained from the phantom models were significantly higher than the control group. The result obtained suggests the phantom as a promising candidate to be used as alternative for toxicology testing in the future.

  5. Full experimental modelling of a liver tissue mimicking phantom for medical ultrasound studies employing different hydrogels.

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    Casciaro, Sergio; Conversano, Francesco; Musio, Stefano; Casciaro, Ernesto; Demitri, Christian; Sannino, Alessandro

    2009-04-01

    Tissue mimicking phantoms have been widely reported to be an important tool for development, optimisation and performance testing of ultrasound-based diagnostic techniques. In particular, modern applications of tissue mimicking phantoms often include characterisation of the nonlinear behaviour of experimental ultrasound contrast agents. In such cases, the tissue-mimicking materials should be chosen not only based on the values of their density, speed of sound and attenuation coefficient, but also considering their effect on the appearance of "native harmonics" due to nonlinear distortion of ultrasound signal during propagation. In a previous paper it was demonstrated that a cellulose-based hydrogel is suitable to simulate nonlinear acoustical behaviour of liver tissue for thicknesses up to 8 cm. In this paper we present the experimental characterisation of the nonlinear acoustical behaviour of a different polyethylene glycol diacrylate (PEGDA)-based hydrogel, in order to assess whether and how it can improve the performances and overcome some limitations of the cellulose-based hydrogel as liver tissue-mimicking material. Samples of pig liver tissue, cellulose-based hydrogel and PEGDA-based hydrogel were insonified in a through-transmission set-up, employing 2.25-MHz pulses with different mechanical index (MI) values. Second harmonic and first harmonic amplitudes were extracted from the spectra of received signals and their difference was then used to compare sample behaviours. Obtained results show how a new more accurate and combined experimental model of linear and nonlinear acoustical behaviour of liver tissue is feasible. In fact, a further confirmation of the cellulose-based hydrogel effectiveness to precisely simulate the liver tissue for penetration depths up to 8 cm was provided, and it was also shown that the employment of the PEGDA-based hydrogel can extend the range of useful tissue-mimicking material thicknesses up to 11 cm, moreover allowing a

  6. A heterogeneous human tissue mimicking phantom for RF heating and MRI thermal monitoring verification.

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    Yuan, Yu; Wyatt, Cory; Maccarini, Paolo; Stauffer, Paul; Craciunescu, Oana; Macfall, James; Dewhirst, Mark; Das, Shiva K

    2012-04-07

    This paper describes a heterogeneous phantom that mimics a human thigh with a deep-seated tumor, for the purpose of studying the performance of radiofrequency (RF) heating equipment and non-invasive temperature monitoring with magnetic resonance imaging (MRI). The heterogeneous cylindrical phantom was constructed with an outer fat layer surrounding an inner core of phantom material mimicking muscle, tumor and marrow-filled bone. The component materials were formulated to have dielectric and thermal properties similar to human tissues. The dielectric properties of the tissue mimicking phantom materials were measured with a microwave vector network analyzer and impedance probe over the frequency range of 80-500 MHz and at temperatures of 24, 37 and 45 °C. The specific heat values of the component materials were measured using a differential scanning calorimeter over the temperature range of 15-55 °C. The thermal conductivity value was obtained from fitting the curves obtained from one-dimensional heat transfer measurement. The phantom was used to verify the operation of a cylindrical four-antenna annular phased array extremity applicator (140 MHz) by examining the proton resonance frequency shift (PRFS) thermal imaging patterns for various magnitude/phase settings (including settings to focus heating in tumors). For muscle and tumor materials, MRI was also used to measure T1/T2* values (1.5 T) and to obtain the slope of the PRFS phase change versus temperature change curve. The dielectric and thermal properties of the phantom materials were in close agreement to well-accepted published results for human tissues. The phantom was able to successfully demonstrate satisfactory operation of the tested heating equipment. The MRI-measured thermal distributions matched the expected patterns for various magnitude/phase settings of the applicator, allowing the phantom to be used as a quality assurance tool. Importantly, the material formulations for the various tissue types

  7. Tissue-mimicking bladder wall phantoms for evaluating acoustic radiation force-optical coherence elastography systems.

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    Ejofodomi, O'tega A; Zderic, Vesna; Zara, Jason M

    2010-04-01

    Acoustic radiation force-optical coherence elastography (ARF-OCE) systems are novel imaging systems that have the potential to simultaneously quantify and characterize the optical and mechanical properties of in vivo tissues. This article presents the construction of bladder wall phantoms for use in ARF-OCE systems. Mechanical, acoustic, and optical properties are reported and compared to published values for the urinary bladder. The phantom consisted of 0.2000 +/- 0.0089 and 6.0000 +/- 0.2830 microm polystyrene microspheres (Polysciences Inc., Warrington, PA, Catalog Nos. 07304 and 07312), 7.5 +/- 1.5 microm copolymer microspheres composed of acrylonitrile and vinylidene chloride, (Expancel, Duluth, GA, Catalog No. 461 DU 20), and bovine serum albumin within a gelatin matrix. Young's modulus was measured by successive compression of the phantom and obtaining the slope of the resulting force-displacement data. Acoustic measurements were performed using the transmission method. The phantoms were submerged in a water bath and placed between transmitting and receiving 13 mm diameter unfocused transducers operating at a frequency of 3.5 MHz. A MATLAB algorithm to extract the optical scattering coefficient from optical coherence tomography (OCT) images of the phantom was used. The phantoms possess a Young's modulus of 17.12 +/- 2.72 kPa, a mass density of 1.05 +/- 0.02 g/cm3, an acoustic attenuation coefficient of 0.66 +/- 0.08 dB/cm/MHz, a speed of sound of 1591 +/- 8.76 m/s, and an optical scattering coefficient of 1.80 +/- 0.23 mm(-1). Ultrasound and OCT images of the bladder wall phantom are presented. A material that mimics the mechanical, optical, and acoustic properties of healthy bladder wall has been developed. This tissue-mimicking bladder wall phantom was developed as a control tool to investigate the feasibility of using ARF-OCE to detect the mechanical and optical changes that may be indicative of the onset or development of cancer in the urinary bladder

  8. Effect of Graphite Concentration on Shear-Wave Speed in Gelatin-Based Tissue-Mimicking Phantoms

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    Anderson, Pamela G.; Rouze, Ned C.; Palmeri, Mark L.

    2011-01-01

    Elasticity-based imaging modalities are becoming popular diagnostic tools in clinical practice. Gelatin-based, tissue mimicking phantoms that contain graphite as the acoustic scattering material are commonly used in testing and validating elasticity-imaging methods to quantify tissue stiffness. The gelatin bloom strength and concentration are used to control phantom stiffness. While it is known that graphite concentration can be modulated to control acoustic attenuation, the impact of graphite concentrationon phantom elasticity has not been characterized in these gelatin phantoms. This work investigates the impact of graphite concentration on phantom shear stiffness as characterized by shear-wave speed measurements using impulsive acoustic-radiation-force excitations. Phantom shear-wave speed increased by 0.83 (m/s)/(dB/(cm MHz)) when increasing the attenuation coefficient slope of the phantom material through increasing graphite concentration. Therefore, gelatin-phantom stiffness can be affected by the conventional ways that attenuation is modulated through graphite concentration in these phantoms. PMID:21710828

  9. Comparison of Ultrasound Attenuation and Backscatter Estimates in Layered Tissue-Mimicking Phantoms among Three Clinical Scanners

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    Nam, Kibo; Rosado-Mendez, Ivan M.; Wirtzfeld, Lauren A.; Ghoshal, Goutam; Pawlicki, Alexander D.; Madsen, Ernest L.; Lavarello, Roberto J.; Oelze, Michael L.; Zagzebski, James A.; O’Brien, William D.; Hall, Timothy J.

    2013-01-01

    Backscatter and attenuation coefficient estimates are needed in many quantitative ultrasound strategies. In clinical applications, these parameters may not be easily obtained because of variations in scattering by tissues overlying a region of interest (ROI). The goal of this study is to assess the accuracy of backscatter and attenuation estimates for regions distal to nonuniform layers of tissue-mimicking materials. In addition, this work compares results of these estimates for “layered” phantoms scanned using different clinical ultrasound machines. Two tissue-mimicking phantoms were constructed, each exhibiting depth-dependent variations in attenuation or backscatter. The phantoms were scanned with three ultrasound imaging systems, acquiring radio frequency echo data for offline analysis. The attenuation coefficient and the backscatter coefficient (BSC) for sections of the phantoms were estimated using the reference phantom method. Properties of each layer were also measured with laboratory techniques on test samples manufactured during the construction of the phantom. Estimates of the attenuation coefficient versus frequency slope, α0, using backscatter data from the different systems agreed to within 0.24 dB/cm-MHz. Bias in the α0 estimates varied with the location of the ROI. BSC estimates for phantom sections whose locations ranged from 0 to 7 cm from the transducer agreed among the different systems and with theoretical predictions, with a mean bias error of 1.01 dB over the used bandwidths. This study demonstrates that attenuation and BSCs can be accurately estimated in layered inhomogeneous media using pulse-echo data from clinical imaging systems. PMID:23160474

  10. Quantitative characterization of viscoelastic behavior in tissue-mimicking phantoms and ex vivo animal tissues.

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    Ashkan Maccabi

    Full Text Available Viscoelasticity of soft tissue is often related to pathology, and therefore, has become an important diagnostic indicator in the clinical assessment of suspect tissue. Surgeons, particularly within head and neck subsites, typically use palpation techniques for intra-operative tumor detection. This detection method, however, is highly subjective and often fails to detect small or deep abnormalities. Vibroacoustography (VA and similar methods have previously been used to distinguish tissue with high-contrast, but a firm understanding of the main contrast mechanism has yet to be verified. The contributions of tissue mechanical properties in VA images have been difficult to verify given the limited literature on viscoelastic properties of various normal and diseased tissue. This paper aims to investigate viscoelasticity theory and present a detailed description of viscoelastic experimental results obtained in tissue-mimicking phantoms (TMPs and ex vivo tissues to verify the main contrast mechanism in VA and similar imaging modalities. A spherical-tip micro-indentation technique was employed with the Hertzian model to acquire absolute, quantitative, point measurements of the elastic modulus (E, long term shear modulus (η, and time constant (τ in homogeneous TMPs and ex vivo tissue in rat liver and porcine liver and gallbladder. Viscoelastic differences observed between porcine liver and gallbladder tissue suggest that imaging modalities which utilize the mechanical properties of tissue as a primary contrast mechanism can potentially be used to quantitatively differentiate between proximate organs in a clinical setting. These results may facilitate more accurate tissue modeling and add information not currently available to the field of systems characterization and biomedical research.

  11. Quantitative characterization of viscoelastic behavior in tissue-mimicking phantoms and ex vivo animal tissues.

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    Maccabi, Ashkan; Shin, Andrew; Namiri, Nikan K; Bajwa, Neha; St John, Maie; Taylor, Zachary D; Grundfest, Warren; Saddik, George N

    2018-01-01

    Viscoelasticity of soft tissue is often related to pathology, and therefore, has become an important diagnostic indicator in the clinical assessment of suspect tissue. Surgeons, particularly within head and neck subsites, typically use palpation techniques for intra-operative tumor detection. This detection method, however, is highly subjective and often fails to detect small or deep abnormalities. Vibroacoustography (VA) and similar methods have previously been used to distinguish tissue with high-contrast, but a firm understanding of the main contrast mechanism has yet to be verified. The contributions of tissue mechanical properties in VA images have been difficult to verify given the limited literature on viscoelastic properties of various normal and diseased tissue. This paper aims to investigate viscoelasticity theory and present a detailed description of viscoelastic experimental results obtained in tissue-mimicking phantoms (TMPs) and ex vivo tissues to verify the main contrast mechanism in VA and similar imaging modalities. A spherical-tip micro-indentation technique was employed with the Hertzian model to acquire absolute, quantitative, point measurements of the elastic modulus (E), long term shear modulus (η), and time constant (τ) in homogeneous TMPs and ex vivo tissue in rat liver and porcine liver and gallbladder. Viscoelastic differences observed between porcine liver and gallbladder tissue suggest that imaging modalities which utilize the mechanical properties of tissue as a primary contrast mechanism can potentially be used to quantitatively differentiate between proximate organs in a clinical setting. These results may facilitate more accurate tissue modeling and add information not currently available to the field of systems characterization and biomedical research.

  12. An examination of the elastic properties of tissue-mimicking phantoms using vibro-acoustography and a muscle motor system

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    Maccabi, A.; Taylor, Z.; Bajwa, N.; Mallen-St. Clair, J.; St. John, M.; Sung, S.; Grundfest, W.; Saddik, G.

    2016-02-01

    Tissue hardness, often quantified in terms of elasticity, is an important differentiating criterion for pathological identity and is extensively used by surgeons for tumor localization. Delineation of malignant regions from benign regions is typically performed by visual inspection and palpation. Although practical, this method is highly subjective and does not provide quantitative metrics. We have previously reported on Vibro-Acoustography (VA) for tumor delineation. VA is unique in that it uses the specific, non-linear properties of tumor tissue in response to an amplitude modulated ultrasound beam to generate spatially resolved, high contrast maps of tissue. Although the lateral and axial resolutions (sub-millimeter and sub-centimeter, respectively) of VA have been extensively characterized, the relationship between static stiffness assessment (palpation) and dynamic stiffness characterization (VA) has not been explicitly established. Here we perform a correlative exploration of the static and dynamic properties of tissue-mimicking phantoms, specifically elasticity, using VA and a muscle motor system. Muscle motor systems, commonly used to probe the mechanical properties of materials, provide absolute, quantitative point measurements of the elastic modulus, analogous to Young's modulus, of a target. For phantoms of varying percent-by-weight concentrations, parallel VA and muscle motor studies conducted on 18 phantoms reveal a negative correlation (p < - 0.85) between mean signal amplitude levels observed with VA and calculated elastic modulus values from force vs. indentation depth curves. Comparison of these elasticity measurements may provide additional information to improve tissue modeling, system characterization, as well as offer valuable insights for in vivo applications, specifically surgical extirpation of tumors.

  13. Mixing formula for tissue-mimicking silicone phantoms in the near infrared

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    Böcklin, C.; Baumann, D.; Stuker, F.; Fröhlich, Jürg

    2015-03-01

    The knowledge of accurate optical parameters of materials is paramount in biomedical optics applications and numerical simulations of such systems. Phantom materials with variable but predefined parameters are needed to optimise these systems. An optimised integrating sphere measurement setup and reconstruction algorithm are presented in this work to determine the optical properties of silicone rubber based phantoms whose absorption and scattering properties are altered with TiO2 and carbon black particles. A mixing formula for all constituents is derived and allows to create phantoms with predefined optical properties.

  14. The effect of magnetic nanoparticles on the acoustic properties of tissue-mimicking agar-gel phantoms

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    Józefczak, A., E-mail: aras@amu.edu.pl [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Kaczmarek, K. [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland); Kubovčíková, M. [Institute of Experimental Physics, Slovak Academy of Sciences, Košice (Slovakia); Rozynek, Z.; Hornowski, T. [Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań (Poland)

    2017-06-01

    In ultrasonic hyperthermia, ultrasound-induced heating is achieved by the absorption of wave energy and its conversion into heat. The effectiveness of ultrasounds can be improved by using sonosensitisers that greatly attenuate ultrasonic waves and then dissipate the acquired energy in the form of heat. One possible candidate for such a sonosensitiser are superparamagnetic iron oxide nanoparticles. Here, we used magnetic nanoparticles embedded in a tissue-mimicking agar-gel matrix. Such tissue-mimicking phantoms possess acoustic properties similar to those of real tissues, and are used as a tool for performance testing and optimisation of medical ultrasound systems. In this work, we studied the effect of magnetic nanoparticles on the acoustic properties of agar-gel phantoms, including the attenuation of ultrasonic waves. - Highlights: • Ultrasonic insertion technique is used to study acoustic properties of agar-gel phantoms with and without magnetic particles. • The addition of magnetic nanoparticles improves effectiveness of ultrasound heating in agar phantoms. • Acoustics properties of a pure agar-gel phantom are altered by adding nanoparticles.

  15. Hydrogel based tissue mimicking phantom for in-vitro ultrasound contrast agents studies.

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    Demitri, Christian; Sannino, Alessandro; Conversano, Francesco; Casciaro, Sergio; Distante, Alessandro; Maffezzoli, Alfonso

    2008-11-01

    Ultrasound medical imaging (UMI) is the most widely used image analysis technique, and often requires advanced in-vitro set up to perform morphological and functional investigations. These studies are based on contrast properties both related to tissue structure and injectable contrast agents (CA). In this work, we present a three-dimensional structure composed of two different hydrogels reassembly the microvascular network of a human tissue. This phantom was particularly suitable for the echocontrastographic measurements in human microvascular system. This phantom has been characterized to present the acoustic properties of an animal liver, that is, acoustic impedance (Z) and attenuation coefficient (AC), in UMI signal analysis in particular; the two different hydrogels have been selected to simulate the target organ and the acoustic properties of the vascular system. The two hydrogels were prepared starting from cellulose derivatives to simulating the target organ parenchyma and using a PEG-diacrylate to reproduce the vascular system. Moreover, harmonic analysis was performed on the hydrogel mimicking the liver parenchyma hydrogel to evaluate the ultrasound (US) distortion during echographic measurement. The phantom was employed in the characterization of an experimental US CA. Perfect agreement was found when comparing the hydrogel acoustical properties materials with the corresponding living reference tissues (i.e., vascular and parenchimal tissue).

  16. Temperature dependence of acoustic harmonics generated by nonlinear ultrasound beam propagation in ex vivo tissue and tissue-mimicking phantoms.

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    Maraghechi, Borna; Kolios, Michael C; Tavakkoli, Jahan

    2015-01-01

    Hyperthermia is a cancer treatment technique that could be delivered as a stand-alone modality or in conjunction with chemotherapy or radiation therapy. Noninvasive and real-time temperature monitoring of the heated tissue improves the efficacy and safety of the treatment. A temperature-sensitive acoustic parameter is required for ultrasound-based thermometry. In this paper the amplitude and the energy of the acoustic harmonics of the ultrasound backscattered signal are proposed as suitable parameters for noninvasive ultrasound thermometry. A commercial high frequency ultrasound imaging system was used to generate and detect acoustic harmonics in tissue-mimicking gel phantoms and ex vivo bovine muscle tissues. The pressure amplitude and the energy content of the backscattered fundamental frequency (p1 and E1), the second (p2 and E2) and the third (p3 and E3) harmonics were detected in pulse-echo mode. Temperature was increased from 26° to 46 °C uniformly through both samples. The amplitude and the energy content of the harmonics and their ratio were measured and analysed as a function of temperature. The average p1, p2 and p3 increased by 69%, 100% and 283%, respectively as the temperature was elevated from 26° to 46 °C in tissue samples. In the same experiment the average E1, E2 and E3 increased by 163%, 281% and 2257%, respectively. A similar trend was observed in tissue-mimicking gel phantoms. The findings suggest that the harmonics generated due to nonlinear ultrasound beam propagation are highly sensitive to temperature and could potentially be used for noninvasive ultrasound tissue thermometry.

  17. Optimizing signal output: effects of viscoelasticity and difference frequency on vibroacoustic radiation of tissue-mimicking phantoms

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    Namiri, Nikan K.; Maccabi, Ashkan; Bajwa, Neha; Badran, Karam W.; Taylor, Zachary D.; St. John, Maie A.; Grundfest, Warren S.; Saddik, George N.

    2018-02-01

    Vibroacoustography (VA) is an imaging technology that utilizes the acoustic response of tissues to a localized, low frequency radiation force to generate a spatially resolved, high contrast image. Previous studies have demonstrated the utility of VA for tissue identification and margin delineation in cancer tissues. However, the relationship between specimen viscoelasticity and vibroacoustic emission remains to be fully quantified. This work utilizes the effects of variable acoustic wave profiles on unique tissue-mimicking phantoms (TMPs) to maximize VA signal power according to tissue mechanical properties, particularly elasticity. A micro-indentation method was utilized to provide measurements of the elastic modulus for each biological replica. An inverse relationship was found between elastic modulus (E) and VA signal amplitude among homogeneous TMPs. Additionally, the difference frequency (Δf ) required to reach maximum VA signal correlated with specimen elastic modulus. Peak signal diminished with increasing Δf among the polyvinyl alcohol specimen, suggesting an inefficient vibroacoustic response by the specimen beyond a threshold of resonant Δf. Comparison of these measurements may provide additional information to improve tissue modeling, system characterization, as well as insights into the unique tissue composition of tumors in head and neck cancer patients.

  18. Preparation of a Carbon Doped Tissue-Mimicking Material with High Dielectric Properties for Microwave Imaging Application

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    Siang-Wen Lan

    2016-07-01

    Full Text Available In this paper, the oil-in-gelatin based tissue-mimicking materials (TMMs doped with carbon based materials including carbon nanotube, graphene ink or lignin were prepared. The volume percent for gelatin based mixtures and oil based mixtures were both around 50%, and the doping amounts were 2 wt %, 4 wt %, and 6 wt %. The effect of doping material and amount on the microwave dielectric properties including dielectric constant and conductivity were investigated over an ultra-wide frequency range from 2 GHz to 20 GHz. The coaxial open-ended reflection technology was used to evaluate the microwave dielectric properties. Six measured values in different locations of each sample were averaged and the standard deviations of all the measured dielectric properties, including dielectric constant and conductivity, were less than one, indicating a good uniformity of the prepared samples. Without doping, the dielectric constant was equal to 23 ± 2 approximately. Results showed with doping of carbon based materials that the dielectric constant and conductivity both increased about 5% to 20%, and the increment was dependent on the doping amount. By proper selection of doping amount of the carbon based materials, the prepared material could map the required dielectric properties of special tissues. The proposed materials were suitable for the phantom used in the microwave medical imaging system.

  19. Piecewise parabolic method for simulating one-dimensional shear shock wave propagation in tissue-mimicking phantoms

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    Tripathi, B. B.; Espíndola, D.; Pinton, G. F.

    2017-11-01

    The recent discovery of shear shock wave generation and propagation in the porcine brain suggests that this new shock phenomenology may be responsible for a broad range of traumatic injuries. Blast-induced head movement can indirectly lead to shear wave generation in the brain, which could be a primary mechanism for injury. Shear shock waves amplify the local acceleration deep in the brain by up to a factor of 8.5, which may tear and damage neurons. Currently, there are numerical methods that can model compressional shock waves, such as comparatively well-studied blast waves, but there are no numerical full-wave solvers that can simulate nonlinear shear shock waves in soft solids. Unlike simplified representations, e.g., retarded time, full-wave representations describe fundamental physical behavior such as reflection and heterogeneities. Here we present a piecewise parabolic method-based solver for one-dimensional linearly polarized nonlinear shear wave in a homogeneous medium and with empirical frequency-dependent attenuation. This method has the advantage of being higher order and more directly extendable to multiple dimensions and heterogeneous media. The proposed numerical scheme is validated analytically and experimentally and compared to other shock capturing methods. A Riemann step-shock problem is used to characterize the numerical dissipation. This dissipation is then tuned to be negligible with respect to the physical attenuation by choosing an appropriate grid spacing. The numerical results are compared to ultrasound-based experiments that measure planar polarized shear shock wave propagation in a tissue-mimicking gelatin phantom. Good agreement is found between numerical results and experiment across a 40 mm propagation distance. We anticipate that the proposed method will be a starting point for the development of a two- and three-dimensional full-wave code for the propagation of nonlinear shear waves in heterogeneous media.

  20. MRI-based morphological modeling, synthesis and characterization of cardiac tissue-mimicking materials.

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    Kossivas, Fotis; Angeli, S; Kafouris, D; Patrickios, C S; Tzagarakis, V; Constantinides, C

    2012-06-01

    This study uses standard synthetic methodologies to produce tissue-mimicking materials that match the morphology and emulate the in vivo murine and human cardiac mechanical and imaging characteristics, with dynamic mechanical analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM) and magnetic resonance imaging. In accordance with such aims, poly(glycerol sebacate) (PGS) elastomeric materials were synthesized (at two different glycerol (G)-sebacic (S) acid molar ratios; the first was synthesized using a G:S molar ratio of 2:2, while the second from a 2:5 G:S molar ratio, resulting in PGS2:2 and PGS2:5 elastomers, respectively). Unlike the synthesized PGS2:2 elastomers, the PGS2:5 materials were characterized by an overall mechanical instability in their loading behavior under the three successive loading conditions tested. An oscillatory response in the mechanical properties of the synthesized elastomers was observed throughout the loading cycles, with measured increased storage modulus values at the first loading cycle, stabilizing to lower values at subsequent cycles. These elastomers were characterized at 4 °C and were found to have storage modulus values of 850 and 1430 kPa at the third loading cycle, respectively, in agreement with previously reported values of the rat and human myocardium. SEM of surface topology indicated minor degradation of synthesized materials at 10 and 20 d post-immersion in the PBS buffer solution, with a noted cluster formation on the PGS2:5 elastomers. AFM nanoindentation experiments were also conducted for the measurement of the Young modulus of the sample surface (no bulk contribution). Correspondingly, the PGS2:2 elastomer indicated significantly decreased surface Young's modulus values 20 d post-PBS immersion, compared to dry conditions (Young's modulus = 1160 ± 290 kPa (dry) and 200 ± 120 kPa (20 d)). In addition to the two-dimensional (2D) elastomers, an integrative platform for accurate construction of

  1. MRI-based morphological modeling, synthesis and characterization of cardiac tissue-mimicking materials

    International Nuclear Information System (INIS)

    Kossivas, Fotis; Angeli, S; Constantinides, C; Kafouris, D; Patrickios, C S; Tzagarakis, V

    2012-01-01

    This study uses standard synthetic methodologies to produce tissue-mimicking materials that match the morphology and emulate the in vivo murine and human cardiac mechanical and imaging characteristics, with dynamic mechanical analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM) and magnetic resonance imaging. In accordance with such aims, poly(glycerol sebacate) (PGS) elastomeric materials were synthesized (at two different glycerol (G)–sebacic (S) acid molar ratios; the first was synthesized using a G:S molar ratio of 2:2, while the second from a 2:5 G:S molar ratio, resulting in PGS2:2 and PGS2:5 elastomers, respectively). Unlike the synthesized PGS2:2 elastomers, the PGS2:5 materials were characterized by an overall mechanical instability in their loading behavior under the three successive loading conditions tested. An oscillatory response in the mechanical properties of the synthesized elastomers was observed throughout the loading cycles, with measured increased storage modulus values at the first loading cycle, stabilizing to lower values at subsequent cycles. These elastomers were characterized at 4 °C and were found to have storage modulus values of 850 and 1430 kPa at the third loading cycle, respectively, in agreement with previously reported values of the rat and human myocardium. SEM of surface topology indicated minor degradation of synthesized materials at 10 and 20 d post-immersion in the PBS buffer solution, with a noted cluster formation on the PGS2:5 elastomers. AFM nanoindentation experiments were also conducted for the measurement of the Young modulus of the sample surface (no bulk contribution). Correspondingly, the PGS2:2 elastomer indicated significantly decreased surface Young's modulus values 20 d post-PBS immersion, compared to dry conditions (Young's modulus = 1160 ± 290 kPa (dry) and 200 ± 120 kPa (20 d)). In addition to the two-dimensional (2D) elastomers, an integrative platform for accurate construction of

  2. Evaluation of temperature rise in a tissue mimicking material during HIFU exposure

    International Nuclear Information System (INIS)

    Maruvada, S; Liu, Y; Herman, B A; Harris, G R

    2011-01-01

    In pre-clinical testing it is essential to characterize clinical high intensity focused ultrasound (HIFU) devices using tissue-mimicking materials (TMMs) with well known characteristics, including temperature rise and cavitation properties. The purpose of this study was to monitor cavitation behavior and correlate its effect with temperature rise in a HIFU TMM containing an embedded thermocouple. A 75-μm fine wire thermocouple was embedded in a hydrogel-based TMM previously developed for HIFU. HIFU at 1.1 and 3.3 MHz was focused at the thermocouple junction. Focal pressures from 1-11 MPa were applied and the temperature profiles were recorded. Three hydrophones were used to monitor cavitation activity during sonication. A hydrophone confocal with the HIFU transducer and a cylindrical hydrophone lateral to the HIFU beam were used as passive cavitation detectors for spectral analysis of signals, and a needle hydrophone placed beyond the HIFU focus was used to record changes in the pressure amplitude due to blockage by bubbles at or near the focus. B-mode imaging scans were employed to visualize bubble presence during sonication. In a separate measurement, schlieren imaging was used to monitor the change in field distribution behind the TMM. All hydrophone methods correlated well with cavitation in the TMM.

  3. Evaluation of temperature rise in a tissue mimicking material during HIFU exposure

    Energy Technology Data Exchange (ETDEWEB)

    Maruvada, S; Liu, Y; Herman, B A; Harris, G R, E-mail: subha.maruvada@fda.hhs.gov [Food and Drug Administration, Center for Devices and Radiological Health, 10903 New Hampshire Ave., Bldg., Silver Spring, MD 20993 (United States)

    2011-02-01

    In pre-clinical testing it is essential to characterize clinical high intensity focused ultrasound (HIFU) devices using tissue-mimicking materials (TMMs) with well known characteristics, including temperature rise and cavitation properties. The purpose of this study was to monitor cavitation behavior and correlate its effect with temperature rise in a HIFU TMM containing an embedded thermocouple. A 75-{mu}m fine wire thermocouple was embedded in a hydrogel-based TMM previously developed for HIFU. HIFU at 1.1 and 3.3 MHz was focused at the thermocouple junction. Focal pressures from 1-11 MPa were applied and the temperature profiles were recorded. Three hydrophones were used to monitor cavitation activity during sonication. A hydrophone confocal with the HIFU transducer and a cylindrical hydrophone lateral to the HIFU beam were used as passive cavitation detectors for spectral analysis of signals, and a needle hydrophone placed beyond the HIFU focus was used to record changes in the pressure amplitude due to blockage by bubbles at or near the focus. B-mode imaging scans were employed to visualize bubble presence during sonication. In a separate measurement, schlieren imaging was used to monitor the change in field distribution behind the TMM. All hydrophone methods correlated well with cavitation in the TMM.

  4. Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials.

    Science.gov (United States)

    Maxwell, Adam D; Cain, Charles A; Hall, Timothy L; Fowlkes, J Brian; Xu, Zhen

    2013-03-01

    In this study, the negative pressure values at which inertial cavitation consistently occurs in response to a single, two-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (P(cav)) for a single pulse as a function of peak negative pressure (p(-)) followed a sigmoid curve, with the probability approaching one when the pressure amplitude was sufficient. The statistical threshold (defined as P(cav) = 0.5) was between p(-) = 26 and 30 MPa in all samples with high water content but varied between p(-) = 13.7 and >36 MPa in other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p(-) = 28.2 megapascals was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at various pressure levels and dimensions of cavitation-induced lesions in tissue. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  5. Polyvinyl chloride as a multimodal tissue-mimicking material with tuned mechanical and medical imaging properties.

    Science.gov (United States)

    Li, Weisi; Belmont, Barry; Greve, Joan M; Manders, Adam B; Downey, Brian C; Zhang, Xi; Xu, Zhen; Guo, Dongming; Shih, Albert

    2016-10-01

    The mechanical and imaging properties of polyvinyl chloride (PVC) can be adjusted to meet the needs of researchers as a tissue-mimicking material. For instance, the hardness can be adjusted by changing the ratio of softener to PVC polymer, mineral oil can be added for lubrication in needle insertion, and glass beads can be added to scatter acoustic energy similar to biological tissue. Through this research, the authors sought to develop a regression model to design formulations of PVC with targeted mechanical and multimodal medical imaging properties. The design of experiment was conducted by varying three factors-(1) the ratio of softener to PVC polymer, (2) the mass fraction of mineral oil, and (3) the mass fraction of glass beads-and measuring the mechanical properties (elastic modulus, hardness, viscoelastic relaxation time constant, and needle insertion friction force) and the medical imaging properties [speed of sound, acoustic attenuation coefficient, magnetic resonance imaging time constants T 1 and T 2 , and the transmittance of the visible light at wavelengths of 695 nm (T λ695 ) and 532 nm (T λ532 )] on twelve soft PVC samples. A regression model was built to describe the relationship between the mechanical and medical imaging properties and the values of the three composition factors of PVC. The model was validated by testing the properties of a PVC sample with a formulation distinct from the twelve samples. The tested soft PVC had elastic moduli from 6 to 45 kPa, hardnesses from 5 to 50 Shore OOO-S, viscoelastic stress relaxation time constants from 114.1 to 191.9 s, friction forces of 18 gauge needle insertion from 0.005 to 0.086 N/mm, speeds of sound from 1393 to 1407 m/s, acoustic attenuation coefficients from 0.38 to 0.61 (dB/cm)/MHz, T 1 relaxation times from 426.3 to 450.2 ms, T 2 relaxation times from 21.5 to 28.4 ms, T λ695 from 46.8% to 92.6%, and T λ532 from 41.1% to 86.3%. Statistically significant factors of each property were

  6. Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers.

    Science.gov (United States)

    Ahn, K J; Kim, B J; Cho, S B

    2017-08-01

    Laser therapy is the treatment of choice in tattoo removal. However, the precise mechanisms of laser-tattoo pigment interactions remain to be evaluated. We evaluated the geometric patterns of laser-tattoo pigment particle interactions using a tattoo pigment-embedded tissue-mimicking (TM) phantom. A Q-switched (QS) neodymium-doped yttrium aluminum garnet laser was used at settings of 532-, 660-, and 1064-nm wavelengths, single-pulse and quick pulse-to-pulse treatment modes, and spot sizes of 4 and 7 mm. Most of the laser-tattoo interactions in the experimental conditions formed cocoon-shaped or oval photothermal and photoacoustic injury zones, which contained fragmented tattoo particles in various sizes depending on the conditions. In addition, a long-pulsed 755-nm alexandrite laser was used at a spot size of 6 mm and pulse widths of 3, 5, and 10 ms. The finer granular pattern of tattoo destruction was observed in TM phantoms treated with 3- and 5-ms pulse durations compared to those treated with a 10-ms pulse. We outlined various patterns of laser-tattoo pigment interactions in a tattoo-embedded TM phantom to predict macroscopic tattoo and surrounding tissue reactions after laser treatment for tattoo removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. 3D conformal MRI-controlled transurethral ultrasound prostate therapy: validation of numerical simulations and demonstration in tissue-mimicking gel phantoms.

    Science.gov (United States)

    Burtnyk, Mathieu; N'Djin, William Apoutou; Kobelevskiy, Ilya; Bronskill, Michael; Chopra, Rajiv

    2010-11-21

    MRI-controlled transurethral ultrasound therapy uses a linear array of transducer elements and active temperature feedback to create volumes of thermal coagulation shaped to predefined prostate geometries in 3D. The specific aims of this work were to demonstrate the accuracy and repeatability of producing large volumes of thermal coagulation (>10 cc) that conform to 3D human prostate shapes in a tissue-mimicking gel phantom, and to evaluate quantitatively the accuracy with which numerical simulations predict these 3D heating volumes under carefully controlled conditions. Eleven conformal 3D experiments were performed in a tissue-mimicking phantom within a 1.5T MR imager to obtain non-invasive temperature measurements during heating. Temperature feedback was used to control the rotation rate and ultrasound power of transurethral devices with up to five 3.5 × 5 mm active transducer elements. Heating patterns shaped to human prostate geometries were generated using devices operating at 4.7 or 8.0 MHz with surface acoustic intensities of up to 10 W cm(-2). Simulations were informed by transducer surface velocity measurements acquired with a scanning laser vibrometer enabling improved calculations of the acoustic pressure distribution in a gel phantom. Temperature dynamics were determined according to a FDTD solution to Pennes' BHTE. The 3D heating patterns produced in vitro were shaped very accurately to the prostate target volumes, within the spatial resolution of the MRI thermometry images. The volume of the treatment difference falling outside ± 1 mm of the target boundary was, on average, 0.21 cc or 1.5% of the prostate volume. The numerical simulations predicted the extent and shape of the coagulation boundary produced in gel to within (mean ± stdev [min, max]): 0.5 ± 0.4 [-1.0, 2.1] and -0.05 ± 0.4 [-1.2, 1.4] mm for the treatments at 4.7 and 8.0 MHz, respectively. The temperatures across all MRI thermometry images were predicted within -0.3 ± 1.6 °C and 0

  8. The response of MRI contrast parameters in in vitro tissues and tissue mimicking phantoms to fractionation by histotripsy

    Science.gov (United States)

    Allen, Steven P.; Vlaisavljevich, Eli; Shi, Jiaqi; Hernandez-Garcia, Luis; Cain, Charles A.; Xu, Zhen; Hall, Timothy L.

    2017-09-01

    Histotripsy is a non-invasive, focused ultrasound lesioning technique that can ablate precise volumes of soft tissue using a novel mechanical fractionation mechanism. Previous research suggests that magnetic resonance imaging (MRI) may be a sensitive image-based feedback mechanism for histotripsy. However, there are insufficient data to form some unified understanding of the response of the MR contrast mechanisms in tissues to histotripsy. In this paper, we investigate the response of the MR contrast parameters R1, R2, and the apparent diffusion coefficient (ADC) to various treatment levels of histotripsy in in vitro porcine liver, kidney, muscle, and blood clot as well in formulations of bovine red blood cells suspended in agar gel. We also make a histological analysis of histotripsy lesions in porcine liver. We find that R2 and the ADC are both sensitive to ablation in all materials tested here, and the degree of response varies with tissue type. Correspondingly, under histologic analysis, the porcine liver exhibited various levels of mechanical disruption and necrotic debris that are characteristic of histotripsy. While the area of intact red blood cells and nuclei found within these lesions both decreased with increasing amounts of treatment, the area of red blood cells decreased much more rapidly than the area of intact nuclei. Additionally, the decrease in area of intact red blood cells saturated at the same treatment levels at which the response of the R2 saturated while the area of intact nuclei appeared to vary linearly with the response of the ADC.

  9. Double-integrating-sphere system at the National Institute of Standards and Technology in support of measurement standards for the determination of optical properties of tissue-mimicking phantoms

    Science.gov (United States)

    Lemaillet, Paul; Bouchard, Jean-Pierre; Hwang, Jeeseong; Allen, David W.

    2015-12-01

    There is a need for a common reference point that will allow for the comparison of the optical properties of tissue-mimicking phantoms. After a brief review of the methods that have been used to measure the phantoms for a contextual backdrop to our approach, this paper reports on the establishment of a standardized double-integrating-sphere platform to measure absorption and reduced scattering coefficients of tissue-mimicking biomedical phantoms. The platform implements a user-friendly graphical user interface in which variations of experimental configurations and model-based analysis are implemented to compute the coefficients based on a modified inverse adding-doubling algorithm allowing a complete uncertainty evaluation. Repeatability and validation of the measurement results of solid phantoms are demonstrated for three samples of different thicknesses, d=5.08 mm, 7.09 mm, and 9.92 mm, with an absolute error estimate of 4.0% to 5.0% for the absorption coefficient and 11% to 12% for the reduced scattering coefficient (k=2). The results are in accordance with those provided by the manufacturer. Measurements with different polarization angles of the incident light are also presented, and the resulting optical properties were determined to be equivalent within the estimated uncertainties.

  10. Pattern analysis of laser-tattoo interactions for picosecond- and nanosecond-domain 1,064-nm neodymium-doped yttrium-aluminum-garnet lasers in tissue-mimicking phantom.

    Science.gov (United States)

    Ahn, Keun Jae; Zheng, Zhenlong; Kwon, Tae Rin; Kim, Beom Joon; Lee, Hye Sun; Cho, Sung Bin

    2017-05-08

    During laser treatment for tattoo removal, pigment chromophores absorb laser energy, resulting in fragmentation of the ink particles via selective photothermolysis. The present study aimed to outline macroscopic laser-tattoo interactions in tissue-mimicking (TM) phantoms treated with picosecond- and nanosecond-domain lasers. Additionally, high-speed cinematographs were captured to visualize time-dependent tattoo-tissue interactions, from laser irradiation to the formation of photothermal and photoacoustic injury zones (PIZs). In all experimental settings using the nanosecond or picosecond laser, tattoo pigments fragmented into coarse particles after a single laser pulse, and further disintegrated into smaller particles that dispersed toward the boundaries of PIZs after repetitive delivery of laser energy. Particles fractured by picosecond treatment were more evenly dispersed throughout PIZs than those fractured by nanosecond treatment. Additionally, picosecond-then-picosecond laser treatment (5-pass-picosecond treatment + 5-pass-picosecond treatment) induced greater disintegration of tattoo particles within PIZs than picosecond-then-nanosecond laser treatment (5-pass-picosecond treatment + 5-pass-nanosecond treatment). High-speed cinematography recorded the formation of PIZs after repeated reflection and propagation of acoustic waves over hundreds of microseconds to a few milliseconds. The present data may be of use in predicting three-dimensional laser-tattoo interactions and associated reactions in surrounding tissue.

  11. A computerized system based on an alternative pulse echo immersion technique for acoustic characterization of non-porous solid tissue mimicking materials

    Science.gov (United States)

    Nazihah Mat Daud, Anis; Jaafar, Rosly; Kadri Ayop, Shahrul; Supar Rohani, Md

    2018-04-01

    This paper discusses the development of a computerized acoustic characterization system of non-porous solid tissue mimicking materials. This system employs an alternative pulse echo immersion technique and consists of a pulser/receiver generator, a transducer used as both a transmitter and a receiver, a digital oscilloscope, and a personal computer with a custom-developed program installed. The program was developed on the LabVIEW 2012 platform and comprises two main components, a user interface and a block diagram. The user interface consists of three panels: a signal acquisition and selection panel, a display panel, and a calculation panel. The block diagram comprises four blocks: a signal acquisition block, a peak signal analysis block, an acoustic properties calculation and display block, and an additional block. Interestingly, the system can be operated in both online and offline modes. For the online mode, the measurements are performed by connecting the system with a Rigol DS2000 Series digital oscilloscope. In contrast, the measurements are carried out by processing the saved data on the computer for the offline mode. The accuracy and consistency of the developed system was validated by a KB-Aerotech Alpha Series transducer with 5 MHz center frequency and a Rigol DS2202 two-channel 200 MHz 2 GSa s-1 digital oscilloscope, based on the measurement of the acoustic properties of three poly(methyl methacrylate) samples immersed in a medium at a temperature of (24.0  ±  0.1) °C. The findings indicated that the accuracy and consistency of the developed system was exceptionally high, within a 1.04% margin of error compared to the reference values. As such, this computerized system can be efficiently used for the acoustic characterization of non-porous solid tissues, given its spontaneous display of results, user-friendly interface, and convenient hardware connection.

  12. Anthropomorphic phantom materials

    International Nuclear Information System (INIS)

    White, D.R.; Constantinou, C.

    1982-01-01

    The need, terminology and history of tissue substitutes are outlined. Radiation properties of real tissues are described and simulation procedures are outlined. Recent tissue substitutes are described and charted, as are calculated radiation classifications. Manufacturing procedures and quality control are presented. Recent phantom studies are reviewed and a discussion recorded. Elemental compositions of the recommended tissue substitutes are charted with elemental composition given for each tissue substitute

  13. Experimental investigation and theoretical modelling of the nonlinear acoustical behaviour of a liver tissue and comparison with a tissue mimicking hydrogel.

    Science.gov (United States)

    Casciaro, Sergio; Demitri, Christian; Conversano, Francesco; Casciaro, Ernesto; Distante, Alessandro

    2008-02-01

    Native harmonics generated by nonlinear distortion of ultrasound during propagation in a medium may cause misinterpretations in spectral analysis when studying contrast agents. The aim of this paper is to quantitatively evaluate nonlinear propagation effects of diagnostic ultrasound pulses in biological tissues and to assess whether a cellulose-based hydrogel can be a suitable material for tissue mimicking purposes. Hydrogel and pig liver tissue samples of various thicknesses were insonified in a through-transmission set-up, employing 2.25-MHz pulses with different mechanical index (MI) values (range 0.06-0.60). Second harmonic and first harmonic amplitudes were extracted from spectra of received signals and their ratio was then used to compare hydrogel and liver behaviours. Resulting trends are very similar for sample thicknesses up to 8 cm and highlight a significant increase in nonlinearity for MI > 0.3, for both liver and hydrogel. A numerical procedure was also employed to calculate pressure distribution along the beam axis: these theoretical results showed a very good agreement with experimental data in the low pressure range, though failed in predicting the MI threshold. In conclusion, the hydrogel resulted to be a suitable material for manufacturing tissue mimicking phantoms, in particular to study contrast agent behaviour with a "low power approach".

  14. Non-invasive ultrasound-based temperature imaging for monitoring radiofrequency heating-phantom results

    International Nuclear Information System (INIS)

    Daniels, M J; Varghese, T; Madsen, E L; Zagzebski, J A

    2007-01-01

    Minimally invasive therapies (such as radiofrequency ablation) are becoming more commonly used in the United States for the treatment of hepatocellular carcinomas and liver metastases. Unfortunately, these procedures suffer from high recurrence rates of hepatocellular carcinoma (∼34-55%) or metastases following ablation therapy. The ability to perform real-time temperature imaging while a patient is undergoing radiofrequency ablation could provide a significant reduction in these recurrence rates. In this paper, we demonstrate the feasibility of ultrasound-based temperature imaging on a tissue-mimicking phantom undergoing radiofrequency heating. Ultrasound echo signals undergo time shifts with increasing temperature, which are tracked using 2D correlation-based speckle tracking methods. Time shifts or displacements in the echo signal are accumulated, and the gradient of these time shifts are related to changes in the temperature of the tissue-mimicking phantom material using a calibration curve generated from experimental data. A tissue-mimicking phantom was developed that can undergo repeated radiofrequency heating procedures. Both sound speed and thermal expansion changes of the tissue-mimicking material were measured experimentally and utilized to generate the calibration curve relating temperature to the displacement gradient. Temperature maps were obtained, and specific regions-of-interest on the temperature maps were compared to invasive temperatures obtained using fiber-optic temperature probes at the same location. Temperature elevation during a radiofrequency ablation procedure on the phantom was successfully tracked to within ±0.5 0 C

  15. A Review on the 3D Printing of Functional Structures for Medical Phantoms and Regenerated Tissue and Organ Applications

    Directory of Open Access Journals (Sweden)

    Kan Wang

    2017-10-01

    Full Text Available Medical models, or “phantoms,” have been widely used for medical training and for doctor-patient interactions. They are increasingly used for surgical planning, medical computational models, algorithm verification and validation, and medical devices development. Such new applications demand high-fidelity, patient-specific, tissue-mimicking medical phantoms that can not only closely emulate the geometric structures of human organs, but also possess the properties and functions of the organ structure. With the rapid advancement of three-dimensional (3D printing and 3D bioprinting technologies, many researchers have explored the use of these additive manufacturing techniques to fabricate functional medical phantoms for various applications. This paper reviews the applications of these 3D printing and 3D bioprinting technologies for the fabrication of functional medical phantoms and bio-structures. This review specifically discusses the state of the art along with new developments and trends in 3D printed functional medical phantoms (i.e., tissue-mimicking medical phantoms, radiologically relevant medical phantoms, and physiological medical phantoms and 3D bio-printed structures (i.e., hybrid scaffolding materials, convertible scaffolds, and integrated sensors for regenerated tissues and organs.

  16. Absolute Ultrasound Perfusion Parameter Quantification of a Tissue-Mimicking Phantom Using Bolus Tracking

    Czech Academy of Sciences Publication Activity Database

    Mézl, M.; Jiřík, Radovan; Harabiš, V.; Kolář, R.; Standara, M.; Nylund, K.; Gilja, O.H.; Taxt, T.

    2015-01-01

    Roč. 62, č. 5 (2015), s. 983-987 ISSN 0885-3010 R&D Projects: GA ČR GAP102/12/2380; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : indicator dilution models * contrast agents * blood-flow * in-vitro * validation Subject RIV: FS - Medical Facilities ; Equipment Impact factor: 2.287, year: 2015

  17. Optical response of the FXG solution to different phantom materials

    International Nuclear Information System (INIS)

    Cavinato, C.C.; Sakuraba, R.K.; Cruz, J.C.; Campos, L.L.

    2011-01-01

    The purpose of this work is to evaluate the performance of the Fricke xylenol gel (FXG) solution developed at IPEN, prepared with 270 Bloom gelatine (made in Brazil), for clinical electron beams to the reference depth, using different phantom materials. The colour change, optical absorption spectra, intra and inter-batches reproducibility, dose-response, lower detection limit, energy and dose rate dependent response and response uniformity were studied. The excellent results obtained indicate the viability of employing this solution in 2D spectrophotometric dosimetry (could be extended to 3D MRI dosimetry) to be applied in quality assurance for clinical radiotherapy treatment planning of superficial tumours being treated with clinical electron beams.

  18. Measurement of guided mode wavenumbers in soft tissue–bone mimicking phantoms using ultrasonic axial transmission

    International Nuclear Information System (INIS)

    Chen Jiangang; Su Zhongqing; Cheng Li; Foiret, Josquin; Minonzio, Jean-Gabriel; Talmant, Maryline; Laugier, Pascal

    2012-01-01

    Human soft tissue is an important factor that influences the assessment of human long bones using quantitative ultrasound techniques. To investigate such influence, a series of soft tissue–bone phantoms (a bone-mimicking plate coated with a layer of water, glycerol or silicon rubber) were ultrasonically investigated using a probe with multi-emitter and multi-receiver arrays in an axial transmission configuration. A singular value decomposition signal processing technique was applied to extract the frequency-dependent wavenumbers of several guided modes. The results indicate that the presence of a soft tissue-mimicking layer introduces additional guided modes predicted by a fluid waveguide model. The modes propagating in the bone-mimicking plate covered by the soft-tissue phantom are only slightly modified compared to their counterparts in the free bone-mimicking plate, and they are still predicted by an elastic transverse isotropic two-dimensional waveguide. Altogether these observations suggest that the soft tissue–bone phantoms can be modeled as two independent waveguides. Even in the presence of the overlying soft tissue-mimicking layer, the modes propagating in the bone-mimicking plate can still be extracted and identified. These results suggest that our approach can be applied for the purpose of the characterization of the material and structural properties of cortical bone. (paper)

  19. A novel composite material specifically developed for ultrasound bone phantoms: cortical, trabecular and skull

    International Nuclear Information System (INIS)

    Wydra, A; Maev, R Gr

    2013-01-01

    In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, help in implementation, testing and calibrations. Phantoms are especially useful in developing new applications and training new doctors in medical schools. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc will require the phantom to be made of different physical properties. In this paper we introduce the properties of recently designed new materials for developing phantoms for ultrasonic human body investigation, which in today's market make up more than 30% in the world of phantoms. We developed a novel composite material which allows fabrication of various kinds of ultrasound bone phantoms to mimic most of the acoustical properties of human bones. In contrast to the ex vivo tissues, the proposed material can maintain the physical and acoustical properties unchanged for long periods of time; moreover, these properties can be custom designed and created to suit specific needs. As a result, we introduce three examples of ultrasound phantoms that we manufactured in our laboratory: cortical, trabecular and skull bone phantoms. The paper also presents the results of a comparison study between the acoustical and physical properties of actual human bones (reported in the referenced literatures) and the phantoms manufactured by us. (note)

  20. ``Phantom'' Modes in Ab Initio Tunneling Calculations: Implications for Theoretical Materials Optimization, Tunneling, and Transport

    Science.gov (United States)

    Barabash, Sergey V.; Pramanik, Dipankar

    2015-03-01

    Development of low-leakage dielectrics for semiconductor industry, together with many other areas of academic and industrial research, increasingly rely upon ab initio tunneling and transport calculations. Complex band structure (CBS) is a powerful formalism to establish the nature of tunneling modes, providing both a deeper understanding and a guided optimization of materials, with practical applications ranging from screening candidate dielectrics for lowest ``ultimate leakage'' to identifying charge-neutrality levels and Fermi level pinning. We demonstrate that CBS is prone to a particular type of spurious ``phantom'' solution, previously deemed true but irrelevant because of a very fast decay. We demonstrate that (i) in complex materials, phantom modes may exhibit very slow decay (appearing as leading tunneling terms implying qualitative and huge quantitative errors), (ii) the phantom modes are spurious, (iii) unlike the pseudopotential ``ghost'' states, phantoms are an apparently unavoidable artifact of large numerical basis sets, (iv) a presumed increase in computational accuracy increases the number of phantoms, effectively corrupting the CBS results despite the higher accuracy achieved in resolving the true CBS modes and the real band structure, and (v) the phantom modes cannot be easily separated from the true CBS modes. We discuss implications for direct transport calculations. The strategy for dealing with the phantom states is discussed in the context of optimizing high-quality high- κ dielectric materials for decreased tunneling leakage.

  1. Laser-generated ultrasound for high-precision cutting of tissue-mimicking gels (Conference Presentation)

    Science.gov (United States)

    Lee, Taehwa; Luo, Wei; Li, Qiaochu; Guo, L. Jay

    2017-03-01

    Laser-generated focused ultrasound has shown great promise in precisely treating cells and tissues by producing controlled micro-cavitation within the acoustic focal volume (30 MPa, negative pressure amplitude). By moving cavitation spots along pre-defined paths through a motorized stage, tissue-mimicking gels of different elastic moduli were cut into different shapes (rectangle, triangle, and circle), leaving behind the same shape of holes, whose sizes are less than 1 mm. The cut line width is estimated to be less than 50 um (corresponding to localized cavitation region), allowing for accurate cutting. This novel approach could open new possibility for in-vivo treatment of diseased tissues in a high-precision manner (i.e., high-precision invisible sonic scalpel).

  2. A theoretical and experimental investigation of nonlinear propagation of ultrasound through tissue mimicking media

    Science.gov (United States)

    Rielly, Matthew Robert

    An existing numerical model (known as the Bergen code) is used to investigate finite amplitude ultrasound propagation through multiple layers of tissue-like media. This model uses a finite difference method to solve the nonlinear parabolic KZK wave equation. The code is modified to include an arbitrary frequency dependence of absorption and transmission effects for wave propagation across a plane interface at normal incidence. In addition the code is adapted to calculate the total intensity loss associated with the absorption of the fundamental and nonlinearly generated harmonics. Measurements are also taken of the axial nonlinear pressure field generated from a circular focused, 2.25 MHz source, through single and multiple layered tissue mimicking fluids, for source pressures in the range from 13 kPa to 310 kPa. Two tissue mimicking fluids are developed to provide acoustic properties similar to amniotic fluid and a typical soft tissue. The values of the nonlinearity parameter, sound velocity and frequency dependence of attenuation for both fluids are presented, and the measurement procedures employed to obtain these characteristics are described in detail. These acoustic parameters, together with the measured source conditions are used as input to the numerical model, allowing the experimental conditions to be simulated. Extensive comparisons are made between the model's predictions and the axial pressure field measurements. Results are presented in the frequency domain showing the fundamental and three subsequent harmonic amplitudes on axis, as a function of axial distance. These show that significant nonlinear distortion can occur through media with characteristics typical of tissue. Time domain waveform comparisons are also made. An excellent agreement is found between theory and experiment indicating that the model can be used to predict nonlinear ultrasound propagation through multiple layers of tissue-like media. The numerical code is also used to model the

  3. ANTHROPOMORPHIC PHANTOMS FOR ASSESSMENT OF STRAIN IMAGING METHODS INVOLVING SALINE-INFUSED SONOHYSTEROGRAPHY

    Science.gov (United States)

    Hobson, Maritza A.; Madsen, Ernest L.; Frank, Gary R.; Jiang, Jingfeng; Shi, Hairong; Hall, Timothy J.; Varghese, Tomy

    2008-01-01

    Two anthropomorphic uterine phantoms were developed which allow assessment and comparison of strain imaging systems adapted for use with saline-infused sonohysterography (SIS). Tissue-mimicking (TM) materials consist of dispersions of safflower oil in gelatin. TM fibroids are stiffer than the TM myometrium/cervix and TM polyps are softer. The first uterine phantom has 3-mm diameter TM fibroids randomly distributed in TM myometrium. The second uterine phantom has a 5-mm and an 8-mm spherical TM fibroid in addition to a 5-mm spherical and a 12.5-mm long (medicine-capsule-shaped) TM endometrial polyp protruding into the endometrial cavity; also, a 10-mm spherical TM fibroid projects from the serosal surface. Strain images using the first phantom show the stiffer 3-mm TM fibroids in the myometrium. Results from the second uterine phantom show that, as expected, parts of inclusions projecting into the uterine cavity will appear very stiff, whether they are stiff or soft. Results from both phantoms show that even though there is a five-fold difference in the Young’s moduli values, there is not a significant difference in the strain in the transition from the TM myometrium to the TM fat. These phantoms allow for realistic comparison and evolution of SIS strain imaging techniques and can aid clinical personnel to develop skills for SIS strain imaging. PMID:18514999

  4. Perturbation correction for alanine dosimeters in different phantom materials in high-energy photon beams.

    Science.gov (United States)

    von Voigts-Rhetz, P; Anton, M; Vorwerk, H; Zink, K

    2016-02-07

    In modern radiotherapy the verification of complex treatments plans is often performed in inhomogeneous or even anthropomorphic phantoms. For dose verification small detectors are necessary and therefore alanine detectors are most suitable. Though the response of alanine for a wide range of clinical photon energies in water is well know, the knowledge about the influence of the surrounding phantom material on the response of alanine is sparse. Therefore we investigated the influence of twenty different surrounding/phantom materials for alanine dosimeters in clinical photon fields via Monte Carlo simulations. The relative electron density of the used materials was in the range [Formula: see text] up to 1.69, covering almost all materials appearing in inhomogeneous or anthropomorphic phantoms used in radiotherapy. The investigations were performed for three different clinical photon spectra ranging from 6 to 25 MV-X and Co-60 and as a result a perturbation correction [Formula: see text] depending on the environmental material was established. The Monte Carlo simulation show, that there is only a small dependence of [Formula: see text] on the phantom material and the photon energy, which is below  ±0.6%. The results confirm the good suitability of alanine detectors for in-vivo dosimetry.

  5. Segmentation and quantification of materials with energy discriminating computed tomography: A phantom study

    International Nuclear Information System (INIS)

    Le, Huy Q.; Molloi, Sabee

    2011-01-01

    Purpose: To experimentally investigate whether a computed tomography (CT) system based on CdZnTe (CZT) detectors in conjunction with a least-squares parameter estimation technique can be used to decompose four different materials. Methods: The material decomposition process was divided into a segmentation task and a quantification task. A least-squares minimization algorithm was used to decompose materials with five measurements of the energy dependent linear attenuation coefficients. A small field-of-view energy discriminating CT system was built. The CT system consisted of an x-ray tube, a rotational stage, and an array of CZT detectors. The CZT array was composed of 64 pixels, each of which is 0.8x0.8x3 mm. Images were acquired at 80 kVp in fluoroscopic mode at 50 ms per frame. The detector resolved the x-ray spectrum into energy bins of 22-32, 33-39, 40-46, 47-56, and 57-80 keV. Four phantoms were constructed from polymethylmethacrylate (PMMA), polyethylene, polyoxymethylene, hydroxyapatite, and iodine. Three phantoms were composed of three materials with embedded hydroxyapatite (50, 150, 250, and 350 mg/ml) and iodine (4, 8, 12, and 16 mg/ml) contrast elements. One phantom was composed of four materials with embedded hydroxyapatite (150 and 350 mg/ml) and iodine (8 and 16 mg/ml). Calibrations consisted of PMMA phantoms with either hydroxyapatite (100, 200, 300, 400, and 500 mg/ml) or iodine (5, 15, 25, 35, and 45 mg/ml) embedded. Filtered backprojection and a ramp filter were used to reconstruct images from each energy bin. Material segmentation and quantification were performed and compared between different phantoms. Results: All phantoms were decomposed accurately, but some voxels in the base material regions were incorrectly identified. Average quantification errors of hydroxyapatite/iodine were 9.26/7.13%, 7.73/5.58%, and 12.93/8.23% for the three-material PMMA, polyethylene, and polyoxymethylene phantoms, respectively. The average errors for the four-material

  6. Characterization of Materials for Use as Optical Phantoms

    International Nuclear Information System (INIS)

    Rascon, E. Ortiz; Bruce, N. C.; Flores Flores, J. O.; Berru, R. Sato

    2010-01-01

    We present the results of optical characterization of silicon dioxide nanoparticle solutions. These are spherical particles with a controlled diameter between 100 nm and 600 nm. The importance of this work lies in using these solutions to develop a phantom with optical properties that closely match those of human breast tissue at near-IR wavelengths. Characterization involves illuminating the solution with a laser beam transmitted through a recipient of known width containing the solution. Resulting intensity profiles from the light spot are measured as function of the detector position. The experiments were realized using light with wavelengths 633 nm and 820 nm. Measured intensity profiles were fitted to the calculated profiles obtained from diffusion theory, using the method of images. Fitting results give us the absorption and transport scatter coefficients. These coefficients can be modified by changing the particle concentration of the solution. We found that these coefficients are the same order of magnitude as those of human tissue reported in published studies.

  7. Characterization of tissue-equivalent materials for use in construction of physical phantoms

    International Nuclear Information System (INIS)

    Souza, Edvan V. de; Oliveira, Alex C.H. de; Vieira, Jose W.; Lima, Fernando R.A.

    2013-01-01

    Phantoms are physical or computational models used to simulate the transport of ionizing radiation, their interactions with human body tissues and evaluate the deposition of energy. Depending on the application, you can build phantoms of various types and features. The physical phantoms are made of materials with behavior similar to human tissues exposed to ionizing radiation, the so-called tissue-equivalent materials. The characterization of various tissue-equivalent materials is important for the choice of materials to be used is appropriate, seeking a better cost-benefit ratio. The main objective of this work is to produce tables containing the main characteristics of tissue-equivalent materials. These tables were produced in Microsoft Office Excel. Among the main features of tissue-equivalent materials that were added to the tables, are density, chemical composition, physical state, chemical stability and solubility. The main importance of this work is to contribute to the construction of high-quality physical phantoms and avoid the waste of materials

  8. Quantification of MRI visibility and artifacts at 3T of liquid fiducial marker in a pancreas tissue-mimicking phantom

    DEFF Research Database (Denmark)

    Schneider, Sergej; Jølck, Rasmus Irming; Troost, Esther Gera Cornelia

    2018-01-01

    Purpose: X-ray-based position verification of the target volume in image-guided radiation therapy (IGRT) of patients with pancreatic ductal adenocarcinoma (PDAC) is currently performed on solid fiducial markers that are implanted under endoscopic ultrasonography. A new biodegradable liquid fiduci...

  9. Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

    Science.gov (United States)

    Craciunescu, O I; Howle, L E; Clegg, S T

    1999-01-01

    Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).

  10. Evaluation of water-mimicking solid phantom materials for use in HDR and LDR brachytherapy dosimetry

    Science.gov (United States)

    Schoenfeld, Andreas A.; Thieben, Maike; Harder, Dietrich; Poppe, Björn; Chofor, Ndimofor

    2017-12-01

    In modern HDR or LDR brachytherapy with photon emitters, fast checks of the dose profiles generated in water or a water-equivalent phantom have to be available in the interest of patient safety. However, the commercially available brachytherapy photon sources cover a wide range of photon emission spectra, and the range of the in-phantom photon spectrum is further widened by Compton scattering, so that the achievement of water-mimicking properties of such phantoms involves high requirements on their atomic composition. In order to classify the degree of water equivalence of the numerous commercially available solid water-mimicking phantom materials and the energy ranges of their applicability, the radial profiles of the absorbed dose to water, D w, have been calculated using Monte Carlo simulations in these materials and in water phantoms of the same dimensions. This study includes the HDR therapy sources Nucletron Flexisource Co-60 HDR (60Co), Eckert und Ziegler BEBIG GmbH CSM-11 (137Cs), Implant Sciences Corporation HDR Yb-169 Source 4140 (169Yb) as well as the LDR therapy sources IsoRay Inc. Proxcelan CS-1 (131Cs), IsoAid Advantage I-125 IAI-125A (125I), and IsoAid Advantage Pd-103 IAPd-103A (103Pd). Thereby our previous comparison between phantom materials and water surrounding a Varian GammaMed Plus HDR therapy 192Ir source (Schoenfeld et al 2015) has been complemented. Simulations were performed in cylindrical phantoms consisting of either water or the materials RW1, RW3, Solid Water, HE Solid Water, Virtual Water, Plastic Water DT, Plastic Water LR, Original Plastic Water (2015), Plastic Water (1995), Blue Water, polyethylene, polystyrene and PMMA. While for 192Ir, 137Cs and 60Co most phantom materials can be regarded as water equivalent, for 169Yb the materials Plastic Water LR, Plastic Water DT and RW1 appear as water equivalent. For the low-energy sources 106Pd, 131Cs and 125I, only Plastic Water LR can be classified as water equivalent.

  11. A tissue phantom for visualization and measurement of ultrasound-induced cavitation damage.

    Science.gov (United States)

    Maxwell, Adam D; Wang, Tzu-Yin; Yuan, Lingqian; Duryea, Alexander P; Xu, Zhen; Cain, Charles A

    2010-12-01

    Many ultrasound studies involve the use of tissue-mimicking materials to research phenomena in vitro and predict in vivo bioeffects. We have developed a tissue phantom to study cavitation-induced damage to tissue. The phantom consists of red blood cells suspended in an agarose hydrogel. The acoustic and mechanical properties of the gel phantom were found to be similar to soft tissue properties. The phantom's response to cavitation was evaluated using histotripsy. Histotripsy causes breakdown of tissue structures by the generation of controlled cavitation using short, focused, high-intensity ultrasound pulses. Histotripsy lesions were generated in the phantom and kidney tissue using a spherically focused 1-MHz transducer generating 15 cycle pulses, at a pulse repetition frequency of 100 Hz with a peak negative pressure of 14 MPa. Damage appeared clearly as increased optical transparency of the phantom due to rupture of individual red blood cells. The morphology of lesions generated in the phantom was very similar to that generated in kidney tissue at both macroscopic and cellular levels. Additionally, lesions in the phantom could be visualized as hypoechoic regions on a B-mode ultrasound image, similar to histotripsy lesions in tissue. High-speed imaging of the optically transparent phantom was used to show that damage coincides with the presence of cavitation. These results indicate that the phantom can accurately mimic the response of soft tissue to cavitation and provide a useful tool for studying damage induced by acoustic cavitation. Copyright © 2010 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  12. Temperature dependence of HU values for various water equivalent phantom materials

    International Nuclear Information System (INIS)

    Homolka, P.; Nowotny, R.; Gahleitner, A.

    2002-01-01

    The temperature dependence of water equivalent phantom materials used in radiotherapy and diagnostic imaging has been investigated. Samples of phantom materials based on epoxy resin, polyethylene, a polystyrene-polypropylene mixture and commercially available phantom materials (Solid Water TM , Gammex RMI and Plastic Water TM , Nuclear Associates) were scanned at temperatures from 15 to 40 deg. C and HU values determined. At a reference temperature of 20 deg. C materials optimized for CT applications give HU values close to zero while the commercial materials show an offset of 119.77 HU (Plastic Water) and 27.69 HU (Solid Water). Temperature dependence was lowest for epoxy-based materials (EPX-W: -0.23 HU deg. C -1 ; Solid Water: -0.25 HU deg. C -1 ) and highest for a polyethylene-based material (X0: -0.72 HU deg. C -1 ). A material based on a mixture of polystyrene and polypropylene (PSPP1: -0.27 HU deg. C -1 ) is comparable to epoxy-based materials and water (-0.29 HU deg. C -1 ). (author)

  13. Simulated study of solid materials used as phantoms

    International Nuclear Information System (INIS)

    Belmonte, Eduardo P.; Pinheiro, Christiano J.G.; Pinto, Nivia G.Villela; Braz, Delson; Pereira Junior, Sielso B.; Lima, Gilberto S.

    2005-01-01

    The aim of this study is to analyze the behavior of electrons in water and compares them with the behavior in the materials you want to analyze. It were simulated, using Monte Carlo code EGS4 (MC), 24 irradiation with electrons of 6 and 20 MeV in different materials (polyethylene C 2 H 4 ) n , polystyrene (C 8 H 8 ) n , lucite (C 5 H 8 O 2 ), nylon (C 6 H 11 NO), water (H 2 O) and solid water (55% polyethylene, polystyrene and 5% 40% calcium oxide). The data show that for the two energies most of radiation does not interact with the first 20 mm materials. However, when analyzed plates of 1 cm, most of the energy is deposited in the first 4 plates in case 6 MeV and in the first ten to 20 MeV electrons, for all materials. In case of similarity in behavior of radiation in water and other materials, it is observed that is in polyethylene and polystyrene that the behaviour of electrons more resembles the behavior in water

  14. Material-specific Conversion Factors for Different Solid Phantoms Used in the Dosimetry of Different Brachytherapy Sources

    Directory of Open Access Journals (Sweden)

    Sedigheh Sina

    2015-07-01

    Full Text Available Introduction Based on Task Group No. 43 (TG-43U1 recommendations, water phantom is proposed as a reference phantom for the dosimetry of brachytherapy sources. The experimental determination of TG-43 parameters is usually performed in water-equivalent solid phantoms. The purpose of this study was to determine the conversion factors for equalizing solid phantoms to water. Materials and Methods TG-43 parameters of low- and high-energy brachytherapy sources (i.e., Pd-103, I-125 and Cs-137 were obtained in different phantoms, using Monte Carlo simulations. The brachytherapy sources were simulated at the center of different phantoms including water, solid water, poly(methyl methacrylate, polystyrene and polyethylene. Dosimetric parameters such as dose rate constant, radial dose function and anisotropy function of each source were compared in different phantoms. Then, conversion factors were obtained to make phantom parameters equivalent to those of water. Results Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water. Conclusion Polynomial coefficients of conversion factors were obtained for all sources to quantitatively compare g(r values in different phantom materials and the radial dose function in water.

  15. Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

    International Nuclear Information System (INIS)

    Surry, K J M; Austin, H J B; Fenster, A; Peters, T M

    2004-01-01

    Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s -1 , and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz) -1 . T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process

  16. The Role of Anthropomorphic Phantoms in Diagnostic Ultrasound Imaging for Disease Characterization (abstract)

    Science.gov (United States)

    Cannon, L. M.; King, D. M.; Browne, J. E.

    2009-04-01

    An anthropomorhic phantom is an object that can mimic a region of the human anatomy. Anthropomorphic phantoms have a variety of roles in diagnostic ultrasound. These roles include quality assurance testing of ultrasound machines, calibration and testing of new imaging techniques, training of sonographers, and-most importantly-use as a tool to obtain a better understanding of disease progression in the relevant anatomy. To be anthropomorphic a phantom must accurately mimic the body in terms of its ultrasonic and mechanical properties, as well as anatomically. The acoustic properties are speed of sound, attenuation, and backscatter. The mechanical properties are elasticity and density. Phantoms are constructed from tissue-mimicking materials (TMMs). TMMs are prepared from a variety of ingredients, such as gelatine, agar, safflower oil, and glass beads. These ingredients are then boiled and cooled under controlled conditions to produce a solid TMM. To determine if the TMM has the correct acoustic properties, acoustic measurements are performed using a scanning acoustic macroscope. Mechanical measurements are also performed to test the elasticity and density properties. TMMs with the correct properties are subsequently put through a series of moulding procedures to produce the anthropomorphic phantom.

  17. Patient-specific cardiac phantom for clinical training and preprocedure surgical planning.

    Science.gov (United States)

    Laing, Justin; Moore, John; Vassallo, Reid; Bainbridge, Daniel; Drangova, Maria; Peters, Terry

    2018-04-01

    Minimally invasive mitral valve repair procedures including MitraClip ® are becoming increasingly common. For cases of complex or diseased anatomy, clinicians may benefit from using a patient-specific cardiac phantom for training, surgical planning, and the validation of devices or techniques. An imaging compatible cardiac phantom was developed to simulate a MitraClip ® procedure. The phantom contained a patient-specific cardiac model manufactured using tissue mimicking materials. To evaluate accuracy, the patient-specific model was imaged using computed tomography (CT), segmented, and the resulting point cloud dataset was compared using absolute distance to the original patient data. The result, when comparing the molded model point cloud to the original dataset, resulted in a maximum Euclidean distance error of 7.7 mm, an average error of 0.98 mm, and a standard deviation of 0.91 mm. The phantom was validated using a MitraClip ® device to ensure anatomical features and tools are identifiable under image guidance. Patient-specific cardiac phantoms may allow for surgical complications to be accounted for preoperative planning. The information gained by clinicians involved in planning and performing the procedure should lead to shorter procedural times and better outcomes for patients.

  18. The Role of Anthropomorphic Phantoms in Diagnostic Ultrasound Imaging for Disease Characterization

    International Nuclear Information System (INIS)

    Cannon, L. M.; King, D. M.; Browne, J. E.

    2009-01-01

    An anthropomorhic phantom is an object that can mimic a region of the human anatomy. Anthropomorphic phantoms have a variety of roles in diagnostic ultrasound. These roles include quality assurance testing of ultrasound machines, calibration and testing of new imaging techniques, training of sonographers, and--most importantly--use as a tool to obtain a better understanding of disease progression in the relevant anatomy. To be anthropomorphic a phantom must accurately mimic the body in terms of its ultrasonic and mechanical properties, as well as anatomically. The acoustic properties are speed of sound, attenuation, and backscatter. The mechanical properties are elasticity and density. Phantoms are constructed from tissue-mimicking materials (TMMs). TMMs are prepared from a variety of ingredients, such as gelatine, agar, safflower oil, and glass beads. These ingredients are then boiled and cooled under controlled conditions to produce a solid TMM. To determine if the TMM has the correct acoustic properties, acoustic measurements are performed using a scanning acoustic macroscope. Mechanical measurements are also performed to test the elasticity and density properties. TMMs with the correct properties are subsequently put through a series of moulding procedures to produce the anthropomorphic phantom.

  19. Density scaling of phantom materials for a 3D dose verification system.

    Science.gov (United States)

    Tani, Kensuke; Fujita, Yukio; Wakita, Akihisa; Miyasaka, Ryohei; Uehara, Ryuzo; Kodama, Takumi; Suzuki, Yuya; Aikawa, Ako; Mizuno, Norifumi; Kawamori, Jiro; Saitoh, Hidetoshi

    2018-05-21

    In this study, the optimum density scaling factors of phantom materials for a commercially available three-dimensional (3D) dose verification system (Delta4) were investigated in order to improve the accuracy of the calculated dose distributions in the phantom materials. At field sizes of 10 × 10 and 5 × 5 cm 2 with the same geometry, tissue-phantom ratios (TPRs) in water, polymethyl methacrylate (PMMA), and Plastic Water Diagnostic Therapy (PWDT) were measured, and TPRs in various density scaling factors of water were calculated by Monte Carlo simulation, Adaptive Convolve (AdC, Pinnacle 3 ), Collapsed Cone Convolution (CCC, RayStation), and AcurosXB (AXB, Eclipse). Effective linear attenuation coefficients (μ eff ) were obtained from the TPRs. The ratios of μ eff in phantom and water ((μ eff ) pl,water ) were compared between the measurements and calculations. For each phantom material, the density scaling factor proposed in this study (DSF) was set to be the value providing a match between the calculated and measured (μ eff ) pl,water . The optimum density scaling factor was verified through the comparison of the dose distributions measured by Delta4 and calculated with three different density scaling factors: the nominal physical density (PD), nominal relative electron density (ED), and DSF. Three plans were used for the verifications: a static field of 10 × 10 cm 2 and two intensity modulated radiation therapy (IMRT) treatment plans. DSF were determined to be 1.13 for PMMA and 0.98 for PWDT. DSF for PMMA showed good agreement for AdC and CCC with 6 MV x ray, and AdC for 10 MV x ray. DSF for PWDT showed good agreement regardless of the dose calculation algorithms and x-ray energy. DSF can be considered one of the references for the density scaling factor of Delta4 phantom materials and may help improve the accuracy of the IMRT dose verification using Delta4. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley

  20. A simple method to evaluate the composition of tissue-equivalent phantom materials

    International Nuclear Information System (INIS)

    Geske, G.

    1977-01-01

    A description is given of a method to calculate the composition of phantom materials with given density and radiation-physical parameters mixed of components, of which are known their chemical composition and their effective specific volumes. By an example of a simple composition with three components the method is illustrated. The results of this example and some experimental details that must be considered are discussed. (orig.) [de

  1. Anatomically realistic ultrasound phantoms using gel wax with 3D printed moulds

    Science.gov (United States)

    Maneas, Efthymios; Xia, Wenfeng; Nikitichev, Daniil I.; Daher, Batol; Manimaran, Maniragav; Wong, Rui Yen J.; Chang, Chia-Wei; Rahmani, Benyamin; Capelli, Claudio; Schievano, Silvia; Burriesci, Gaetano; Ourselin, Sebastien; David, Anna L.; Finlay, Malcolm C.; West, Simeon J.; Vercauteren, Tom; Desjardins, Adrien E.

    2018-01-01

    Here we describe methods for creating tissue-mimicking ultrasound phantoms based on patient anatomy using a soft material called gel wax. To recreate acoustically realistic tissue properties, two additives to gel wax were considered: paraffin wax to increase acoustic attenuation, and solid glass spheres to increase backscattering. The frequency dependence of ultrasound attenuation was well described with a power law over the measured range of 3-10 MHz. With the addition of paraffin wax in concentrations of 0 to 8 w/w%, attenuation varied from 0.72 to 2.91 dB cm-1 at 3 MHz and from 6.84 to 26.63 dB cm-1 at 10 MHz. With solid glass sphere concentrations in the range of 0.025-0.9 w/w%, acoustic backscattering consistent with a wide range of ultrasonic appearances was achieved. Native gel wax maintained its integrity during compressive deformations up to 60%; its Young’s modulus was 17.4  ±  1.4 kPa. The gel wax with additives was shaped by melting and pouring it into 3D printed moulds. Three different phantoms were constructed: a nerve and vessel phantom for peripheral nerve blocks, a heart atrium phantom, and a placental phantom for minimally-invasive fetal interventions. In the first, nerves and vessels were represented as hyperechoic and hypoechoic tubular structures, respectively, in a homogeneous background. The second phantom comprised atria derived from an MRI scan of a patient with an intervening septum and adjoining vena cavae. The third comprised the chorionic surface of a placenta with superficial fetal vessels derived from an image of a post-partum human placenta. Gel wax is a material with widely tuneable ultrasound properties and mechanical characteristics that are well suited for creating patient-specific ultrasound phantoms in several clinical disciplines.

  2. Monte Carlo modeling of 60 Co HDR brachytherapy source in water and in different solid water phantom materials

    Directory of Open Access Journals (Sweden)

    Sahoo S

    2010-01-01

    Full Text Available The reference medium for brachytherapy dose measurements is water. Accuracy of dose measurements of brachytherapy sources is critically dependent on precise measurement of the source-detector distance. A solid phantom can be precisely machined and hence source-detector distances can be accurately determined. In the present study, four different solid phantom materials such as polymethylmethacrylate (PMMA, polystyrene, Solid Water, and RW1 are modeled using the Monte Carlo methods to investigate the influence of phantom material on dose rate distributions of the new model of BEBIG 60 Co brachytherapy source. The calculated dose rate constant is 1.086 ± 0.06% cGy h−1 U−1 for water, PMMA, polystyrene, Solid Water, and RW1. The investigation suggests that the phantom materials RW1 and Solid Water represent water-equivalent up to 20 cm from the source. PMMA and polystyrene are water-equivalent up to 10 cm and 15 cm from the source, respectively, as the differences in the dose data obtained in these phantom materials are not significantly different from the corresponding data obtained in liquid water phantom. At a radial distance of 20 cm from the source, polystyrene overestimates the dose by 3% and PMMA underestimates it by about 8% when compared to the corresponding data obtained in water phantom.

  3. Development of an Arm Phantom for Testing Non-Invasive Blood Pressure Monitors

    Science.gov (United States)

    Anderson-Jackson, LaTecia D.

    Approximately one in every three adults age 20 older are diagnosed with high blood pressure or hypertension. It is estimated that hypertension affects 78 million people in the United States, is equally prevalent in both men and woman (Crabtree, Stuart-Shor, & McAllister, 2013). In the United States, around 78% of people suffering from hypertension are aware of their condition, with only 68% using hypertensive medications to control their blood pressure (Writing Group et al., 2010). Clinically, blood pressure measurements may lack accuracy, which can be attributed to various factors, including device limitations, cuff mis-sizing and misplacement, white-coat effect, masked hypertension, and lifestyle factors. The development of an arm phantom to simulate physiologic properties of a human arm and arterial BP waveforms may allow us to better assess the accuracy of non-invasive blood pressure (NIBP) monitors. The objective of this study are to: (1) Develop an arm phantom to replicate physiological properties of the human arm, and (2) Incorporate the arm phantom into a mock circulatory flow loop to simulate different physiological blood pressure readings on the bench. A tissue mimicking material, styrene-ethylene-butylene-styrene (SEBS), a co-block polymer was used to develop the arm phantom for in-vitro testing. To determine the optimal mechanical properties for the arm phantom, individual arm components were isolated and tested. A protocol was developed to evaluate various components for optimal arm phantom development. Mechanical testing was conducted on 10%, 15%, and 20% SEBS gel samples for modulus of elasticity measurements in order to simulate physiological properties of the human arm. As a result of the SEBS polymer being a new material for this application, this investigation will contribute to resolving the limitations that occurred during experimentation. In this study, we demonstrated that although SEBS polymer may be an ideal material to use for simulating

  4. Water equivalence of some plastic-water phantom materials for clinical proton beam dosimetry

    International Nuclear Information System (INIS)

    Al-Sulaiti, L.; Shipley, D.; Thomas, R.; Owen, P.; Kacperek, A.; Regan, P.H.; Palmans, H.

    2012-01-01

    Plastic-water phantom materials are not exactly water equivalent since they have a different elemental composition and different interaction cross sections for protons than water. Several studies of the water equivalence of plastic-water phantom materials have been reported for photon and electron beams, but none for clinical proton beams. In proton beams, the difference between non-elastic nuclear interactions in plastic-water phantom materials compared to those in water should be considered. In this work, the water equivalence of Plastic Water ® (PW) 1 , Plastic Water ® Diagnostic Therapy (PWDT) 1 and solid water (WT1) 2 phantoms was studied for clinical proton energies of 60 MeV and 200 MeV. This was done by evaluating the fluence correction factor at equivalent depths; first with respect to water and then with respect to graphite by experiment and Monte Carlo (MC) simulations using FLUKA. MC simulations showed that the fluence correction with respect to water was less than 0.5% up to the entire penetration depth of the protons at 60 MeV and less than 1% at 200 MeV up to 20 cm depth for PWDT, PW and WT1. With respect to graphite the fluence correction was about 0.5% for 60 MeV and about 4% for 200 MeV. The experimental results for modulated and un-modulated 60 MeV proton beams showed good agreement with the MC simulated fluence correction factors with respect to graphite deviating less than 1% from unity for the three plastic-water phantoms. - Highlights: ► We study plastic-water in clinical proton beams by experiment and Monte Carlo. ► We obtain fluence correction factors for water and graphite. ► The correction factor for water was close to 1 at 60 MeV and <0.990 at 200 MeV. ► The correction factor for graphite was ∼0.5% at 60 MeV and up to 4% at 200 MeV.

  5. Evaluation of two water-equivalent phantom materials for output calibration of photon and electron beams

    International Nuclear Information System (INIS)

    Liu Lizhong; Prasad, Satish C.; Bassano, Daniel A.

    2003-01-01

    Two commercially available water-equivalent solid phantom materials were evaluated for output calibration in both photon (6-15 MV) and electron (6-20 MeV) beams. The solid water 457 and virtual water materials have the same chemical composition but differ in manufacturing process and density. A Farmer-type ionization chamber was used for measuring the output of the photon beams at 5- and 10-cm depth and electron beams at maximum buildup depth in the solid phantoms and in natural water. The water-equivalency correction factor for the solid materials is defined as the ratio of the chamber reading in natural water to that in the solid at the same linear depth. For photon beams, the correction factor was found to be independent of depth and was 0.987 and 0.993 for 6- and 15-MV beams, respectively, for solid water. For virtual water, the corresponding correction factors were 0.993 and 0.998 for 6- and 15-MV beams, respectively. For electron beams, the correction factors ranged from 1.013 to 1.007 for energies of 6 to 20 MeV for both solid materials. This indicated that the water-equivalency of these materials is within ± 1.3%, making them suitable substitutes for natural water in both photon and electron beam output measurements over a wide energy range. These correction factors are slightly larger than the manufacturers' advertised values (± 1.0% for solid water and ± 0.5% for virtual water). We suggest that these corrections are large enough in most cases and should be applied in the calculation of beam outputs

  6. Characterization of the phantom material virtual water in high-energy photon and electron beams.

    Science.gov (United States)

    McEwen, M R; Niven, D

    2006-04-01

    The material Virtual Water has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence-the water/Virtual Water dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement (water and Virtual Water at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Water. However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values.

  7. 3D perfused brain phantom for interstitial ultrasound thermal therapy and imaging: design, construction and characterization

    International Nuclear Information System (INIS)

    Martínez, José M; Jarosz, Boguslaw J

    2015-01-01

    Thermal therapy has emerged as an independent modality of treating some tumors. In many clinics the hyperthermia, one of the thermal therapy modalities, has been used adjuvant to radio- or chemotherapy to substantially improve the clinical treatment outcomes. In this work, a methodology for building a realistic brain phantom for interstitial ultrasound low dose-rate thermal therapy of the brain is proposed. A 3D brain phantom made of the tissue mimicking material (TMM) had the acoustic and thermal properties in the 20–32 °C range, which is similar to that of a brain at 37 °C. The phantom had 10–11% by mass of bovine gelatin powder dissolved in ethylene glycol. The TMM sonicated at 1 MHz, 1.6 MHz and 2.5 MHz yielded the amplitude attenuation coefficients of 62  ±  1 dB m −1 , 115  ±  4 dB m −1 and 175  ±  9 dB m −1 , respectively. The density and acoustic speed determination at room temperature (∼24 °C) gave 1040  ±  40 kg m −3 and 1545  ±  44 m s −1 , respectively. The average thermal conductivity was 0.532 W m −1  K −1 . The T1 and T2 values of the TMM were 207  ±  4 and 36.2  ±  0.4 ms, respectively. We envisage the use of our phantom for treatment planning and for quality assurance in MRI based temperature determination. Our phantom preparation methodology may be readily extended to other thermal therapy technologies. (paper)

  8. Photoacoustic microscopy of bilirubin in tissue phantoms

    Science.gov (United States)

    Zhou, Yong; Zhang, Chi; Yao, Da-Kang; Wang, Lihong V.

    2012-12-01

    Determining both bilirubin's concentration and its spatial distribution are important in disease diagnosis. Here, for the first time, we applied quantitative multiwavelength photoacoustic microscopy (PAM) to detect bilirubin concentration and distribution simultaneously. By measuring tissue-mimicking phantoms with different bilirubin concentrations, we showed that the root-mean-square error of prediction has reached 0.52 and 0.83 mg/dL for pure bilirubin and for blood-mixed bilirubin detection (with 100% oxygen saturation), respectively. We further demonstrated the capability of the PAM system to image bilirubin distribution both with and without blood. Finally, by underlaying bilirubin phantoms with mouse skins, we showed that bilirubin can be imaged with consistent accuracy down to >400 μm in depth. Our results show that PAM has potential for noninvasive bilirubin monitoring in vivo, as well as for further clinical applications.

  9. 'It's All Done With Mirrors': V.S. Ramachandran and the Material Culture of Phantom Limb Research.

    Science.gov (United States)

    Guenther, Katja

    2016-07-01

    This article examines the material culture of neuroscientist Vilayanur S. Ramachandran's research into phantom limbs. In the 1990s Ramachandran used a 'mirror box' to 'resurrect' phantom limbs and thus to treat the pain that often accompanied them. The experimental success of his mirror therapy led Ramachandran to see mirrors as a useful model of brain function, a tendency that explains his attraction to work on 'mirror neurons'. I argue that Ramachandran's fascination with and repeated appeal to the mirror can be explained by the way it allowed him to confront a perennial problem in the mind and brain sciences, that of the relationship between a supposedly immaterial mind and a material brain. By producing what Ramachandran called a 'virtual reality', relating in varied and complex ways to the material world, the mirror reproduced a form of psycho-physical parallelism and dualistic ontology, while conforming to the materialist norms of neuroscience today.

  10. Electrical characterization of bolus material as phantom for use in electrical impedance and computed tomography fusion imaging

    Directory of Open Access Journals (Sweden)

    Parvind Kaur Grewal

    2014-04-01

    Full Text Available 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.

  11. SU-E-T-608: Perturbation Corrections for Alanine Dosimeters in Different Phantom Materials in High-Energy Photon Beams

    International Nuclear Information System (INIS)

    Voigts-Rhetz, P von; Czarnecki, D; Anton, M; Zink, K

    2015-01-01

    Purpose: Alanine dosimeters are often used for in-vivo dosimetry purposes in radiation therapy. In a Monte Carlo study the influence of 20 different surrounding/phantom materials for alanine dosimeters was investigated. The investigations were performed in high-energy photon beams, covering the whole range from 60 Co up to 25 MV-X. The aim of the study is the introduction of a perturbation correction k env for alanine dosimeters accounting for the environmental material. Methods: The influence of different surrounding materials on the response of alanine dosimeters was investigated with Monte Carlo simulations using the EGSnrc code. The photon source was adapted with BEAMnrc to a 60 Co unit and an Elekta (E nom =6, 10, 25 MV-X) linear accelerator. Different tissue-equivalent materials ranging from cortical bone to lung were investigated. In addition to available phantom materials, some material compositions were taken and scaled to different electron densities. The depth of the alanine detectors within the different phantom materials corresponds to 5 cm depth in water, i.e. the depth is scaled according to the electron density (n e /n e,w ) of the corresponding phantom material. The dose was scored within the detector volume once for an alanine/paraffin mixture and once for a liquid water voxel. The relative response, the ratio of the absorbed dose to alanine to the absorbed dose to water, was calculated and compared to the corresponding ratio under reference conditions. Results: For each beam quality the relative response r and the correction factor for the environment kenv was calculated. k env =0.9991+0.0049 *((n e /n e,w )−0.7659) 3 Conclusion: A perturbation correction factor k env accounting for the phantom environment has been introduced. The response of the alanine dosimeter can be considered independent of the surrounding material for relative electron densities (n e /n e,w ) between 1 and 1.4. For denser materials such as bone or much less dense

  12. Passive multi-frequency brain imaging and hyperthermia irradiation apparatus: the use of dielectric matching materials in phantom experiments

    International Nuclear Information System (INIS)

    Gouzouasis, Ioannis; Karathanasis, Konstantinos; Karanasiou, Irene; Uzunoglu, Nikolaos

    2009-01-01

    In this paper a hybrid system able to provide focused microwave radiometry and deep brain hyperthermia is experimentally tested. The system's main module is an ellipsoidal conductive wall cavity which acts as a beam former, focusing the electromagnetic energy on the medium of interest. The system's microwave radiometry component has extensively been studied theoretically and experimentally in the past few years with promising results. In this work, further investigation concerning the improvement of the hybrid system's focusing properties is conducted. Specifically, microwave radiometry and hyperthermia experiments are performed using water phantoms surrounded by dielectric layers used as matching material to enhance detection/penetration depth and spatial resolution. The results showed that the dielectric material reduces the reflected electromagnetic energy on the air–phantom interface, resulting in improved temperature resolution and higher detection or penetration of the energy when microwave radiometry and hyperthermia are applied respectively

  13. Human stem cell based corneal tissue mimicking structures using laser-assisted 3D bioprinting and functional bioinks.

    Science.gov (United States)

    Sorkio, Anni; Koch, Lothar; Koivusalo, Laura; Deiwick, Andrea; Miettinen, Susanna; Chichkov, Boris; Skottman, Heli

    2018-07-01

    stromal structures attached to the host tissue with signs of hASCs migration from the printed structure. This is the first study to demonstrate the feasibility of 3D LaBP for corneal applications using human stem cells and successful fabrication of layered 3D bioprinted tissues mimicking the structure of the native corneal tissue. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Evaluation of some water - equivalent plastics as phantom materials for electron dosimetry

    International Nuclear Information System (INIS)

    Mihailescu, D.; Borcia, C.

    2005-01-01

    In the International Code of Practice for Dosimetry TRS-398 published by the International Atomic Energy Agency (IAEA), water is recommended as the reference medium for the determination of absorbed dose for high-energy electron beams. Plastic phantoms may be used under certain circumstances (electron energy below 10 MeV, R 50 2 ) for electron beam dosimetry. In this case, a depth-scaling factor is required for the conversion of depth in solid phantoms to depth in water. A fluence-scaling factor is also necessary for converting ionization chamber readings in plastic phantom to readings in water. The aim of this paper is to calculate, using Monte Carlo simulations, the depth-scaling factors c pl and fluence-scaling factors h pl of some commercially available water substitute solid phantoms in order to evaluate their water equivalency. Two sets of calculations were performed: one for electron pencil beams and another for 10 x 10 cm 2 parallel beams, both of which are normally incident on water and solid phantoms. We used only mono-energetic beams of 6, 9, 12, 15, and 18 MeV. The results were compared with TRS-398 recommended values. In the case of pencil beams, we found that by applying the TRS-398 protocol, unacceptable uncertainties (up to 10%) were introduced in the dose distribution calculations. By contrast, TRS-398 can safely be used for 10 x 10 cm 2 beams (reference beams). In this case, uncertainties lower than 1% were obtained, what was in agreement with other published data. (authors)

  15. Does standoff material affect acoustic radiation force impulse elastography? A preclinical study of a modified elastography phantom

    Directory of Open Access Journals (Sweden)

    Katharina Hollerieth

    2018-04-01

    Full Text Available Purpose This study was conducted to determine the influence of standoff material on acoustic radiation force impulse (ARFI measurements in an elasticity phantom by using two different probes. Methods Using ARFI elastography, 10 observers measured the shear wave velocity (SWV, m/sec in different lesions of an elasticity phantom with a convex 4C1 probe and a linear 9L4 probe. The experimental setup was expanded by the use of an interposed piece of porcine muscle as standoff material. The probe pressure on the phantom was registered. Results Faulty ARFI measurements occurred more often when quantifying the hardest lesion (74.0 kPa 4.97 m/sec by the 9L4 probe with the porcine muscle as a standoff material interposed between the probe and the phantom. The success rate for ARFI measurements in these series was 52.4%, compared with 99.5% in the other series. The SWV values measured with the 9L4 probe were significantly higher (3.33±1.39 m/sec vs. 2.60±0.74 m/sec, P<0.001 in the group without muscle and were closer to the reference value than those measured with the 4C1 probe (0.25±0.23 m/sec vs. 0.85±1.21 m/sec, P<0.001 in the same group. The SWV values measured when using the muscle as a standoff material were lower than those without the muscle (significant for 9L4, P=0.040. The deviation from the reference value and the variance increased significantly with the 9L4 probe if the muscle was in situ (B=0.27, P=0.004 and B=0.32, P<0.001. In our study, the pressure exerted by the operator had no effect on the SWV values. Conclusion The presence of porcine muscle acting as a standoff material influenced the occurrence of failed measurements as well as the variance and the accuracy of the measured values. The linear high-frequency probe was particularly affected.

  16. Determination of tissue equivalent materials of a physical 8-year-old phantom for use in computed tomography

    International Nuclear Information System (INIS)

    Akhlaghi, Parisa; Miri Hakimabad, Hashem; Rafat Motavalli, Laleh

    2015-01-01

    This paper reports on the methodology applied to select suitable tissue equivalent materials of an 8-year phantom for use in computed tomography (CT) examinations. To find the appropriate tissue substitutes, first physical properties (physical density, electronic density, effective atomic number, mass attenuation coefficient and CT number) of different materials were studied. Results showed that, the physical properties of water and polyurethane (as soft tissue), B-100 and polyvinyl chloride (PVC) (as bone) and polyurethane foam (as lung) agree more with those of original tissues. Then in the next step, the absorbed doses in the location of 25 thermoluminescent dosimeters (TLDs) as well as dose distribution in one slice of phantom were calculated for original and these proposed materials by Monte Carlo simulation at different tube voltages. The comparisons suggested that at tube voltages of 80 and 100 kVp using B-100 as bone, water as soft tissue and polyurethane foam as lung is suitable for dosimetric study in pediatric CT examinations. In addition, it was concluded that by considering just the mass attenuation coefficient of different materials, the appropriate tissue equivalent substitutes in each desired X-ray energy range could be found. - Highlights: • A methodology to select tissue equivalent materials for use in CT was proposed. • Physical properties of different materials were studied. • TLDs dose and dose distribution were calculated for original and proposed materials. • B-100 as bone, and water as soft tissue are best substitute materials at 80 kVp. • Mass attenuation coefficient is determinant for selecting best tissue substitutes

  17. Symbol phantoms

    International Nuclear Information System (INIS)

    Yamaguchi, Hiroshi; Hongo, Syozo; Takeshita, Hiroshi

    1990-01-01

    We have developed Japanese phantoms in two procedures for computation of organ doses exposed to internal and/or external radiation sources. One method is to make mathematical phantoms on the basis of ORNL mathematical phantoms. Parameters to specify organs of Japanese mathematical phantom are determined by interpolations of the ORNL data, which define the organs of Caucasian males and females of various ages, i.e. new born, 1, 5, 10, 15 years and adult, with survey data for Japanese physiques. Another procedure is to build 'symbol phantoms' for the Japanese public. The concept and its method of the symbol phantom enables us to make a phantom for an individual when we have all of his transversal section images obtained by a medical imaging device like MRI, and thus we may achieve more realistic phantoms for Japanese public than the mathematical phantoms. Both studies are in progress in NIRS. (author)

  18. Characterization of the phantom material Virtual WaterTM in high-energy photon and electron beams

    International Nuclear Information System (INIS)

    McEwen, M.R.; Niven, D.

    2006-01-01

    The material Virtual Water TM has been characterized in photon and electron beams. Range-scaling factors and fluence correction factors were obtained, the latter with an uncertainty of around 0.2%. This level of uncertainty means that it may be possible to perform dosimetry in a solid phantom with an accuracy approaching that of measurements in water. Two formulations of Virtual Water TM were investigated with nominally the same elemental composition but differing densities. For photon beams neither formulation showed exact water equivalence--the water/Virtual Water TM dose ratio varied with the depth of measurement with a difference of over 1% at 10 cm depth. However, by using a density (range) scaling factor very good agreement ( TM at all depths was obtained. In the case of electron beams a range-scaling factor was also required to match the shapes of the depth dose curves in water and Virtual Wate TM . However, there remained a difference in the measured fluence in the two phantoms after this scaling factor had been applied. For measurements around the peak of the depth-dose curve and the reference depth this difference showed some small energy dependence but was in the range 0.1%-0.4%. Perturbation measurements have indicated that small slabs of material upstream of a detector have a small (<0.1% effect) on the chamber reading but material behind the detector can have a larger effect. This has consequences for the design of experiments and in the comparison of measurements and Monte Carlo-derived values

  19. Dose Measurements in a Phantom Simulating Neonates by Using Different TL Materials: LiF:Mg,Cu,P and LiF:Mg,Ti

    International Nuclear Information System (INIS)

    Saez-Vergara, J.C.; Romero, A.M.; Fernandez, C.; Gomez, S.; Vazquez, J.; Olivares, M.P.

    1999-01-01

    A study reproducing usual exposure conditions in a special care baby unit has been performed to measure doses using TL materials in a versatile phantom specially designed for neonates having X ray examinations. The phantom offers the possibilities of reproducing different patient thicknesses and representing either a solid or hollow lung region. The results of the dose measurements using TL materials at the entrance, exit and both laterals of the phantom during different chest radiograph conditions are presented. Test conditions were reproduced in both hollow and solid chest cages simulating patient thicknesses of 5, 6 and 7 cm. The study was completed using two types of TL materials, LiF:Mg,Cu,P and LiF:Mg,Ti, in order to analyse and correct the differences on energy response between the two phosphors. (author)

  20. Silicone-based composite materials simulate breast tissue to be used as ultrasonography training phantoms.

    Science.gov (United States)

    Ustbas, Burcin; Kilic, Deniz; Bozkurt, Ayhan; Aribal, Mustafa Erkin; Akbulut, Ozge

    2018-03-02

    A silicone-based composite breast phantom is fabricated to be used as an education model in ultrasonography training. A matrix of silicone formulations is tracked to mimic the ultrasonography and tactile response of human breast tissue. The performance of two different additives: (i) silicone oil and (ii) vinyl-terminated poly (dimethylsiloxane) (PDMS) are monitored by a home-made acoustic setup. Through the use of 75 wt% vinyl-terminated PDMS in two-component silicone elastomer mixture, a sound velocity of 1.29 ± 0.09 × 10 3  m/s and an attenuation coefficient of 12.99 ± 0.08 dB/cm-values those match closely to the human breast tissue-are measured with 5 MHz probe. This model can also be used for needle biopsy as well as for self-exam trainings. Herein, we highlight the fabrication of a realistic, durable, accessible, and cost-effective training platform that contains skin layer, inner breast tissue, and tumor masses. Copyright © 2018. Published by Elsevier B.V.

  1. Characterization of tissue-equivalent materials for use in construction of physical phantoms; Caracterizacao de materiais tecido-equivalentes para uso em construcao de fantomas fisicos

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Edvan V. de, E-mail: edvanmsn@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFFPE), Recife, PE (Brazil); Oliveira, Alex C.H. de, E-mail: oliveira_ach@yahoo.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Vieira, Jose W., E-mail: jose.wilson59@uol.com.br [Escola Politecnica de Pernambuco (UPE), Recife, PE (Brazil); Lima, Fernando R.A., E-mail: falima@cenen.gov.br [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2013-07-01

    Phantoms are physical or computational models used to simulate the transport of ionizing radiation, their interactions with human body tissues and evaluate the deposition of energy. Depending on the application, you can build phantoms of various types and features. The physical phantoms are made of materials with behavior similar to human tissues exposed to ionizing radiation, the so-called tissue-equivalent materials. The characterization of various tissue-equivalent materials is important for the choice of materials to be used is appropriate, seeking a better cost-benefit ratio. The main objective of this work is to produce tables containing the main characteristics of tissue-equivalent materials. These tables were produced in Microsoft Office Excel. Among the main features of tissue-equivalent materials that were added to the tables, are density, chemical composition, physical state, chemical stability and solubility. The main importance of this work is to contribute to the construction of high-quality physical phantoms and avoid the waste of materials.

  2. Potential of gadolinium as contrast material in second generation dual energy computed tomography - An ex vivo phantom study.

    Science.gov (United States)

    Bongers, Malte N; Schabel, Christoph; Krauss, Bernhard; Claussen, Claus D; Nikolaou, Konstantin; Thomas, Christoph

    To evaluate the potential of gadolinium (Gd) as contrast material (CM) in second generation dual energy computed tomography (DECT). In a phantom model, DECT post-processing was used to increase Gd attenuation using advanced monoenergetic extrapolation (MEI), to create virtual non-contrast images (Gd-VNC) and Gd maps and to quantify Gd content. Dilutions of Gd and iodinated CM (7-296 HU) were filled in syringes, placed in an attenuation phantom and scanned with standard DECT protocols (80 &100/Sn140 kV). MEI (40-190 keV) and VNC images as well as Gd maps were computed. The amount of Gd was quantified and the accuracy was compared to iodine images. Linear regression models were calculated to evaluate Gd attenuation of equivolume CM doses and clinical MRI doses. Applying monoenergetic reconstructions and using Gd as contrast agent (Gd MEI 40 keV) doubled Hounsfield-Units (HU) and 90% of the SNR (averaged: 225 HU, SNR3.1) are achievable, as compared to iodinated CM at 120 kV (averaged:110 HU, SNR3.5), at Gd doses of 1.0mmol/kg BW. The accuracies of Gd-VNC (deviation, 6±12 HU) images and Gd quantification (measurement error, 17%) were not significantly different to those of iodine enhanced images (VNC:deviation, 2±11 HU; measurement error,14%). Using monoenergetic extrapolation at 40keV, it is possible to increase Gd-CM attenuation significantly. Thus, equivalent HU and half the SNR in comparison to a standard dose of ICM at 120kV can be expected at a Gd-CM dose of 0.5mmol/kg BW. Post-processing features of iodine based DECT like monoenergetic or VNC images, iodine maps or quantification of CM are feasible with the use of Gd-CM. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Crack phantoms: localized damage correlations and failure in network models of disordered materials

    International Nuclear Information System (INIS)

    Zaiser, M; Moretti, P; Lennartz-Sassinek, S

    2015-01-01

    We study the initiation of failure in network models of disordered materials such as random fuse and spring models, which serve as idealized representations of fracture processes in quasi-two-dimensional, disordered material systems. We consider two different geometries, namely rupture of thin sheets and delamination of thin films, and demonstrate that irrespective of geometry and implementation of the disorder (random failure thresholds versus dilution disorder) failure initiation is associated with the emergence of typical localized correlation structures in the damage patterns. These structures (‘crack phantoms’) exhibit well-defined characteristic lengths, which relate to the failure stress by scaling relations that are typical for critical crack nuclei in disorder-free materials. We discuss our findings in view of the fundamental nature of failure processes in materials with random microstructural heterogeneity. (paper)

  4. SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

    International Nuclear Information System (INIS)

    Mahon, RN; Riblett, MJ; Hugo, GD

    2016-01-01

    Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing on samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical

  5. SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

    Energy Technology Data Exchange (ETDEWEB)

    Mahon, RN; Riblett, MJ; Hugo, GD [Virginia Commonwealth University, Richmond, VA (United States)

    2016-06-15

    Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing on samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical

  6. Doppler ultrasound compatible plastic material for use in rigid flow models.

    Science.gov (United States)

    Wong, Emily Y; Thorne, Meghan L; Nikolov, Hristo N; Poepping, Tamie L; Holdsworth, David W

    2008-11-01

    A technique for the rapid but accurate fabrication of multiple flow phantoms with variations in vascular geometry would be desirable in the investigation of carotid atherosclerosis. This study demonstrates the feasibility and efficacy of implementing numerically controlled direct-machining of vascular geometries into Doppler ultrasound (DUS)-compatible plastic for the easy fabrication of DUS flow phantoms. Candidate plastics were tested for longitudinal speed of sound (SoS) and acoustic attenuation at the diagnostic frequency of 5 MHz. Teflon was found to have the most appropriate SoS (1376 +/- 40 m s(-1) compared with 1540 m s(-1) in soft tissue) and thus was selected to construct a carotid bifurcation flow model with moderate eccentric stenosis. The vessel geometry was machined directly into Teflon using a numerically controlled milling technique. Geometric accuracy of the phantom lumen was verified using nondestructive micro-computed tomography. Although Teflon displayed a higher attenuation coefficient than other tested materials, Doppler data acquired in the Teflon flow model indicated that sufficient signal power was delivered throughout the depth of the vessel and provided comparable velocity profiles to that obtained in the tissue-mimicking phantom. Our results indicate that Teflon provides the best combination of machinability and DUS compatibility, making it an appropriate choice for the fabrication of rigid DUS flow models using a direct-machining method.

  7. Characterization of materials for use in anthropomorphic phantoms produced by 3D printing

    International Nuclear Information System (INIS)

    Solc, J.; Burianova, L.; Vrba, T.

    2018-01-01

    This poster describes the characterization of materials suitable for 3D printing with an emphasis on the determination of photon flux fluctuation factor. Samples of different materials (ABS, HiPS, NYLON, PET, PLA, PVA, PMMA, Polycarbonate, etc.) were obtained from several commercial companies for which the density, Linear Attenuation (LA) and Hounsfield Units (HU) were determined. LA was obtained for photon energies of 59.5 keV, 121.8 and 344.5 keV using collimated volumes of radionuclide sources Am-241 and Eu-152. These energies cover the energy range of CT scanners and the most widely used therapeutic radionuclide I-131. The mean HU was determined from DICOM images obtained on the Philips Brilliance CT Big Bore radiotherapy simulator. Material parameters were compared to water and soft and fat tissues. The results show that the properties of 3D print samples are strongly dependent both on the printer type and its settings, as well as on the print thread. (authors)

  8. Evaluation of 3D printing materials for fabrication of a novel multi-functional 3D thyroid phantom for medical dosimetry and image quality

    International Nuclear Information System (INIS)

    Alssabbagh, Moayyad; Tajuddin, Abd Aziz; Abdulmanap, Mahayuddin; Zainon, Rafidah

    2017-01-01

    Recently, the three-dimensional printer has started to be utilized strongly in medical industries. In the human body, many parts or organs can be printed from 3D images to meet accurate organ geometries. In this study, five common 3D printing materials were evaluated in terms of their elementary composition and the mass attenuation coefficients. The online version of XCOM photon cross-section database was used to obtain the attenuation values of each material. The results were compared with the attenuation values of the thyroid listed in the International Commission on Radiation Units and Measurements - ICRU 44. Two original thyroid models (hollow-inside and solid-inside) were designed from scratch to be used in nuclear medicine, diagnostic radiology and radiotherapy for dosimetry and image quality purposes. Both designs have three holes for installation of radiation dosimeters. The hollow-inside model has more two holes in the top for injection the radioactive materials. The attenuation properties of the Polylactic Acid (PLA) material showed a very good match with the thyroid tissue, which it was selected to 3D print the phantom using open source RepRap, Prusa i3 3D printer. The scintigraphy images show that the phantom simulates a real healthy thyroid gland and thus it can be used for image quality purposes. The measured CT numbers of the PA material after the 3D printing show a close match with the human thyroid CT numbers. Furthermore, the phantom shows a good accommodation of the TLD dosimeters inside the holes. The 3D fabricated thyroid phantom simulates the real shape of the human thyroid gland with a changeable geometrical shape-size feature to fit different age groups. By using 3D printing technology, the time required to fabricate the 3D phantom was considerably shortened compared to the longer conventional methods, where it took only 30 min to print out the model. The 3D printing material used in this study is commercially available and cost

  9. Synthesis and characterization of breast-phantom-based gelatine-glutaraldehyde-TiO2 as a test material for the application of breast cancer diagnosis

    Science.gov (United States)

    Ukhrowiyah, Nuril; Setyaningsih, Novi; Hikmawati, Dyah; Yasin, Moh

    2017-05-01

    Synthesis of breast-phantom-based on gelatine-glutaraldehyde-TiO2 as testing material of breast cancer diagnosis using Near Infrared-Diffuse Optical Tomography (NIR-DOT) is presented. Glutaraldehyde (GA) is added to obtain optimum breast phantom which has same elasticity modulus with mammae. First, synthesis is conducted by mixing gelatine with various amounts of 1 g, 2 g and 3 g with saline solution on 40° C temperature for 30 minutes until they become homogenous. Next, GA with concentration of 0.5 and 1.0% is added. The characterization includes FTIR test, physical test, and mechanical test used to identify group of gelatine’s functions. Elasticity modulus of breast phantom of gelatine composition 2 g and 0.5% GA is obtained at 53.46 kPA which is the approximation of mammae culture elasticity. This composition is chosen to synthesise the next step. In the second step, TiO2 is added with variation of 0.01 g, 0.015 g, 0.02 g, 0.025 g, and 0,03 g. With this variation, it is aimed to get a breast phantom providing image with optimum absorption. The test of this material uses Differential Scanning Calorimetry (DSC), homogeneity test, and analysis of coefficient absorption. The result shows the sample has a good thermal property in the range of 40 - 70° C with a good homogeneity and absorption coefficient of 0.4 mm-1.

  10. Phantom-less bone mineral density (BMD) measurement using dual energy computed tomography-based 3-material decomposition

    Science.gov (United States)

    Hofmann, Philipp; Sedlmair, Martin; Krauss, Bernhard; Wichmann, Julian L.; Bauer, Ralf W.; Flohr, Thomas G.; Mahnken, Andreas H.

    2016-03-01

    Osteoporosis is a degenerative bone disease usually diagnosed at the manifestation of fragility fractures, which severely endanger the health of especially the elderly. To ensure timely therapeutic countermeasures, noninvasive and widely applicable diagnostic methods are required. Currently the primary quantifiable indicator for bone stability, bone mineral density (BMD), is obtained either by DEXA (Dual-energy X-ray absorptiometry) or qCT (quantitative CT). Both have respective advantages and disadvantages, with DEXA being considered as gold standard. For timely diagnosis of osteoporosis, another CT-based method is presented. A Dual Energy CT reconstruction workflow is being developed to evaluate BMD by evaluating lumbar spine (L1-L4) DE-CT images. The workflow is ROI-based and automated for practical use. A dual energy 3-material decomposition algorithm is used to differentiate bone from soft tissue and fat attenuation. The algorithm uses material attenuation coefficients on different beam energy levels. The bone fraction of the three different tissues is used to calculate the amount of hydroxylapatite in the trabecular bone of the corpus vertebrae inside a predefined ROI. Calibrations have been performed to obtain volumetric bone mineral density (vBMD) without having to add a calibration phantom or to use special scan protocols or hardware. Accuracy and precision are dependent on image noise and comparable to qCT images. Clinical indications are in accordance with the DEXA gold standard. The decomposition-based workflow shows bone degradation effects normally not visible on standard CT images which would induce errors in normal qCT results.

  11. Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry in carbon-ion radiotherapy

    International Nuclear Information System (INIS)

    Kanematsu, Nobuyuki; Koba, Yusuke; Ogata, Risa

    2013-01-01

    Purpose: Beam range control is the essence of radiotherapy with heavy charged particles. In conventional broad-beam delivery, fine range adjustment is achieved by insertion of range shifting and compensating materials. In dosimetry, solid phantoms are often used for convenience. These materials should ideally be equivalent to water. In this study, the authors evaluated dosimetric water equivalence of four common plastics, high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polyoxymethylene (POM). Methods: Using the Bethe formula for energy loss, the Gottschalk formula for multiple scattering, and the Sihver formula for nuclear interactions, the authors calculated the effective densities of the plastics for these interactions. The authors experimentally measured variation of the Bragg peak of carbon-ion beams by insertion of HDPE, PMMA, and POM, which were compared with analytical model calculations. Results: The theoretical calculation resulted in slightly reduced multiple scattering and severely increased nuclear interactions for HDPE, compared to water and the other plastics. The increase in attenuation of carbon ions for 20-cm range shift was experimentally measured to be 8.9% for HDPE, 2.5% for PMMA, and 0.0% for POM while PET was theoretically estimated to be in between PMMA and POM. The agreement between the measurements and the calculations was about 1% or better. Conclusions: For carbon-ion beams, POM was dosimetrically indistinguishable from water and the best of the plastics examined in this study. The poorest was HDPE, which would reduce the Bragg peak by 0.45% per cm range shift, although with marginal superiority for reduced multiple scattering. Between the two clear plastics, PET would be superior to PMMA in dosimetric water equivalence.

  12. Evaluation of 3D printing materials for fabrication of a novel multi-functional 3D thyroid phantom for medical dosimetry and image quality

    Science.gov (United States)

    Alssabbagh, Moayyad; Tajuddin, Abd Aziz; Abdulmanap, Mahayuddin; Zainon, Rafidah

    2017-06-01

    Recently, the three-dimensional printer has started to be utilized strongly in medical industries. In the human body, many parts or organs can be printed from 3D images to meet accurate organ geometries. In this study, five common 3D printing materials were evaluated in terms of their elementary composition and the mass attenuation coefficients. The online version of XCOM photon cross-section database was used to obtain the attenuation values of each material. The results were compared with the attenuation values of the thyroid listed in the International Commission on Radiation Units and Measurements - ICRU 44. Two original thyroid models (hollow-inside and solid-inside) were designed from scratch to be used in nuclear medicine, diagnostic radiology and radiotherapy for dosimetry and image quality purposes. Both designs have three holes for installation of radiation dosimeters. The hollow-inside model has more two holes in the top for injection the radioactive materials. The attenuation properties of the Polylactic Acid (PLA) material showed a very good match with the thyroid tissue, which it was selected to 3D print the phantom using open source RepRap, Prusa i3 3D printer. The scintigraphy images show that the phantom simulates a real healthy thyroid gland and thus it can be used for image quality purposes. The measured CT numbers of the PA material after the 3D printing show a close match with the human thyroid CT numbers. Furthermore, the phantom shows a good accommodation of the TLD dosimeters inside the holes. The 3D fabricated thyroid phantom simulates the real shape of the human thyroid gland with a changeable geometrical shape-size feature to fit different age groups. By using 3D printing technology, the time required to fabricate the 3D phantom was considerably shortened compared to the longer conventional methods, where it took only 30 min to print out the model. The 3D printing material used in this study is commercially available and cost

  13. Phantom Pain

    Science.gov (United States)

    ... Because this is yet another version of tangled sensory wires, the result can be pain. A number of other factors are believed to contribute to phantom pain, including damaged nerve endings, scar tissue at the site of the amputation and the physical memory of pre-amputation pain in the affected area. ...

  14. Solid water phantom

    International Nuclear Information System (INIS)

    Arguiropulo, M.Y.; Ghilardi Neto, T.; Pela, C.A.; Ghilardi, A.J.P.

    1992-01-01

    A phantom were developed for simulating water, based in plastics. The material was evaluated for different energies, and the measures of relative transmission showed that the transmission and the water were inside of 0,6% for gamma rays. The results of this new material were presented, showing that it could be used in photon beam calibration with energies on radiotherapy range. (C.G.C.)

  15. Assessment of the accuracy of an ultrasound elastography liver scanning system using a PVA-cryogel phantom with optimal acoustic and mechanical properties.

    Science.gov (United States)

    Cournane, S; Cannon, L; Browne, J E; Fagan, A J

    2010-10-07

    The accuracy of a transient elastography liver-scanning ultrasound system was assessed using a novel application of PVA-cryogel as a tissue-mimicking material with acoustic and shear elasticity properties optimized to best represent those of liver tissue. Although the liver-scanning system has been shown to offer a safer alternative for diagnosing liver cirrhosis through stiffness measurement, as compared to the liver needle biopsy exam, the scanner's accuracy has not been fully established. Young's elastic modulus values of 5-6 wt% PVA-cryogel phantoms, also containing glycerol and 0.3 µm Al(2)O(3) and 3 µm Al(2)O(3), were measured using a 'gold standard' mechanical testing technique and transient elastography. The mechanically measured values and acoustic velocities of the phantoms ranged between 1.6 and 16.1 kPa and 1540 and 1570 m s(-1), respectively, mimicking those observed in liver tissue. The values reported by the transient elastography system overestimated Young's elastic modulus values representative of the progressive stages of liver fibrosis by up to 32%. These results were attributed to the relative rather than absolute nature of the measurement arising from the single-point acoustic velocity calibration of the system, rendering the measurements critically dependent on the speed of sound of the sample under investigation. Given the wide range of acoustic velocities which exist in the liver, spanning healthy tissue to cirrhotic pathology, coupled with the system's assumption that the liver is approximately elastic when it is rather highly viscoelastic, care should be exercised when interpreting the results from this system in patient groups.

  16. Assessment of the accuracy of an ultrasound elastography liver scanning system using a PVA-cryogel phantom with optimal acoustic and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cournane, S; Fagan, A J [Department of Medical Physics and Bioengineering, St James' s Hospital, Dublin 8 (Ireland); Cannon, L; Browne, J E [Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Kevin' s Street, Dublin 8 (Ireland)

    2010-10-07

    The accuracy of a transient elastography liver-scanning ultrasound system was assessed using a novel application of PVA-cryogel as a tissue-mimicking material with acoustic and shear elasticity properties optimized to best represent those of liver tissue. Although the liver-scanning system has been shown to offer a safer alternative for diagnosing liver cirrhosis through stiffness measurement, as compared to the liver needle biopsy exam, the scanner's accuracy has not been fully established. Young's elastic modulus values of 5-6 wt% PVA-cryogel phantoms, also containing glycerol and 0.3 {mu}m Al{sub 2}O{sub 3} and 3 {mu}m Al{sub 2}O{sub 3}, were measured using a 'gold standard' mechanical testing technique and transient elastography. The mechanically measured values and acoustic velocities of the phantoms ranged between 1.6 and 16.1 kPa and 1540 and 1570 m s{sup -1}, respectively, mimicking those observed in liver tissue. The values reported by the transient elastography system overestimated Young's elastic modulus values representative of the progressive stages of liver fibrosis by up to 32%. These results were attributed to the relative rather than absolute nature of the measurement arising from the single-point acoustic velocity calibration of the system, rendering the measurements critically dependent on the speed of sound of the sample under investigation. Given the wide range of acoustic velocities which exist in the liver, spanning healthy tissue to cirrhotic pathology, coupled with the system's assumption that the liver is approximately elastic when it is rather highly viscoelastic, care should be exercised when interpreting the results from this system in patient groups.

  17. SU-E-J-210: Characterizing Tissue Equivalent Materials for the Development of a Dual MRI-CT Heterogeneous Anthropomorphic Phantom Designed Specifically for MRI Guided Radiotherapy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Steinmann, A; Stafford, R; Yung, J; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: MRI guided radiotherapy (MRIgRT) is an emerging technology which will eventually require a proficient quality auditing system. Due to different principles in which MR and CT acquire images, there is a need for a multi-imaging-modality, end-to-end QA phantom for MRIgRT. The purpose of this study is to identify lung, soft tissue, and tumor equivalent substitutes that share similar human-like CT and MR properties (i.e. Hounsfield units and relaxation times). Methods: Materials of interested such as common CT QA phantom materials, and other proprietary gels/silicones from Polytek, SmoothOn, and CompositeOne were first scanned on a GE 1.5T Signa HDxT MR. Materials that could be seen on both T1-weighted and T2-weighted images were then scanned on a GE Lightspeed RT16 CT simulator and a GE Discovery 750HD CT scanner and their HU values were then measured. The materials with matching HU values of lung (−500 to −700HU), muscle (+40HU) and soft tissue (+100 to +300HU) were further scanned on GE 1.5T Signa HDx to measure their T1 and T2 relaxation times from varying parameters of TI and TE. Results: Materials that could be visualized on T1-weighted and T2-weighted images from a 1.5T MR unit and had an appropriate average CT number, −650, −685, 46,169, and 168 HUs were: compressed cork saturated with water, Polytek Platsil™ Gel-00 combined with mini styrofoam balls, radiotherapy bolus material, SmoothOn Dragon-Skin™ and SmoothOn Ecoflex™, respectively. Conclusion: Post processing analysis is currently being performed to accurately map T1 and T2 values for each material tested. From previous MR visualization and CT examinations it is expected that Dragon-Skin™, Ecoflex™ and bolus will have values consistent with tissue and tumor substitutes. We also expect compressed cork statured with water, and Polytek™-styrofoam combination to have approximate T1 and T2 values suitable for lung-equivalent materials.

  18. SU-E-J-210: Characterizing Tissue Equivalent Materials for the Development of a Dual MRI-CT Heterogeneous Anthropomorphic Phantom Designed Specifically for MRI Guided Radiotherapy Systems

    International Nuclear Information System (INIS)

    Steinmann, A; Stafford, R; Yung, J; Followill, D

    2015-01-01

    Purpose: MRI guided radiotherapy (MRIgRT) is an emerging technology which will eventually require a proficient quality auditing system. Due to different principles in which MR and CT acquire images, there is a need for a multi-imaging-modality, end-to-end QA phantom for MRIgRT. The purpose of this study is to identify lung, soft tissue, and tumor equivalent substitutes that share similar human-like CT and MR properties (i.e. Hounsfield units and relaxation times). Methods: Materials of interested such as common CT QA phantom materials, and other proprietary gels/silicones from Polytek, SmoothOn, and CompositeOne were first scanned on a GE 1.5T Signa HDxT MR. Materials that could be seen on both T1-weighted and T2-weighted images were then scanned on a GE Lightspeed RT16 CT simulator and a GE Discovery 750HD CT scanner and their HU values were then measured. The materials with matching HU values of lung (−500 to −700HU), muscle (+40HU) and soft tissue (+100 to +300HU) were further scanned on GE 1.5T Signa HDx to measure their T1 and T2 relaxation times from varying parameters of TI and TE. Results: Materials that could be visualized on T1-weighted and T2-weighted images from a 1.5T MR unit and had an appropriate average CT number, −650, −685, 46,169, and 168 HUs were: compressed cork saturated with water, Polytek Platsil™ Gel-00 combined with mini styrofoam balls, radiotherapy bolus material, SmoothOn Dragon-Skin™ and SmoothOn Ecoflex™, respectively. Conclusion: Post processing analysis is currently being performed to accurately map T1 and T2 values for each material tested. From previous MR visualization and CT examinations it is expected that Dragon-Skin™, Ecoflex™ and bolus will have values consistent with tissue and tumor substitutes. We also expect compressed cork statured with water, and Polytek™-styrofoam combination to have approximate T1 and T2 values suitable for lung-equivalent materials

  19. 3D Printing Openable Imaging Phantom Design

    International Nuclear Information System (INIS)

    Kim, Myoung Keun; Won, Jun Hyeok; Lee, Seung Wook

    2017-01-01

    The purpose of this study is to design an openable phantom that can replace the internal measurement bar used for contrast comparison in order to increase the efficiency of manufacturing imaging phantom used in the medical industry and to improve convenience using 3D printer. Phantom concept design, 3D printing, and Image reconstruction were defined as the scope of the thesis. Also, we study metal artifact reduction with openable phantom. We have designed a Openable phantom using 3D printing, and have investigated metal artifact reduction after inserting a metallic material inside the phantom. The openable phantom can be adjusted at any time to suit the user's experiment and can be easily replaced and useful.

  20. Reflective terahertz (THz) imaging: system calibration using hydration phantoms

    Science.gov (United States)

    Bajwa, Neha; Garritano, James; Lee, Yoon Kyung; Tewari, Priyamvada; Sung, Shijun; Maccabi, Ashkan; Nowroozi, Bryan; Babakhanian, Meghedi; Sanghvi, Sajan; Singh, Rahul; Grundfest, Warren; Taylor, Zachary

    2013-02-01

    Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein, was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with statistically significant hydration sensitivities (p hydration). The THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and intervention of corneal pathologies.

  1. Phantom position dependence

    International Nuclear Information System (INIS)

    Thorson, M.R.; Endres, G.W.R.

    1981-01-01

    Sensitivity of the Hanford dosimeter response to its position relative to the phantom and the neutron source has always been recognized. A thorough investigation was performed to quantify dosimeter response according to: (a) dosimeter position on phantom, (b) dosimeter distance from phantom, and (c) angular relationship of dosimeter relative to neutron source and phantom. Results were obtained for neutron irradiation at several different energies

  2. Spectra from 2.5-15 μm of tissue phantom materials, optical clearing agents and ex vivo human skin: implications for depth profiling of human skin

    International Nuclear Information System (INIS)

    Viator, John A; Choi, Bernard; Peavy, George M; Kimel, Sol; Nelson, J Stuart

    2003-01-01

    Infrared measurements have been used to profile or image biological tissue, including human skin. Usually, analysis of such measurements has assumed that infrared absorption is due to water and collagen. Such an assumption may be reasonable for soft tissue, but introduction of exogenous agents into skin or the measurement of tissue phantoms has raised the question of their infrared absorption spectrum. We used Fourier transform infrared spectroscopy in attenuated total reflection mode to measure the infrared absorption spectra, in the range of 2-15 μm, of water, polyacrylamide, Intralipid, collagen gels, four hyperosmotic clearing agents (glycerol, 1,3-butylene glycol, trimethylolpropane, Topicare TM ), and ex vivo human stratum corneum and dermis. The absorption spectra of the phantom materials were similar to that of water, although additional structure was noted in the range of 6-10 μm. The absorption spectra of the clearing agents were more complex, with molecular absorption bands dominating between 6 and 12 μm. Dermis was similar to water, with collagen structure evident in the 6-10 μm range. Stratum corneum had a significantly lower absorption than dermis due to a lower content of water. These results suggest that the assumption of water-dominated absorption in the 2.5-6 μm range is valid. At longer wavelengths, clearing agent absorption spectra differ significantly from the water spectrum. This spectral information can be used in pulsed photothermal radiometry or utilized in the interpretation of reconstructions in which a constant μ ir is used. In such cases, overestimating μ ir will underestimate chromophore depth and vice versa, although the effect is dependent on actual chromophore depth. (note)

  3. Technical Note: A new phantom design for routine testing of Doppler ultrasound.

    Science.gov (United States)

    Grice, J V; Pickens, D R; Price, R R

    2016-07-01

    The objective of this project is to demonstrate the principle and operation for a simple, inexpensive, and highly portable Doppler ultrasound quality assurance (QA) phantom intended for routine QA testing. A prototype phantom has been designed, fabricated, and evaluated. The phantom described here is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. Many commercially available Doppler ultrasound testing systems can suffer from issues such as a lengthy setup, prohibitive cost, nonportable size, or difficulty in use. This new phantom design aims to address some of these problems and create a phantom appropriate for assessing Doppler ultrasound stability. The phantom was fabricated using a 3D printer. The basic design of the phantom is to provide gravity-powered flow of a Doppler fluid between two reservoirs. The printed components were connected with latex tubing and then seated in a tissue mimicking gel. Spectral Doppler waveforms were sampled to evaluate variations in the data, and the phantom was evaluated using high frame rate video to find an alternate measure of mean fluid velocity flowing in the phantom. The current system design maintains stable flow from one reservoir to the other for approximately 7 s. Color Doppler imaging of the phantom was found to be qualitatively consistent with laminar flow. Using pulsed spectral Doppler, the average fluid velocity from a sample volume approximately centered in the synthetic vessel was measured to be 56 cm/s with a standard deviation of 3.2 cm/s across 118 measurements. An independent measure of the average fluid velocity was measured to be 51.9 cm/s with a standard deviation of 0.7 cm/s over 4 measurements. The developed phantom provides stable fluid flow useful for frequent clinical Doppler ultrasound testing and attempts to address several obstacles facing Doppler phantom testing. Such an ultrasound phantom can make routine

  4. Computer tomographic phantom

    International Nuclear Information System (INIS)

    Lonn, A.H.R.; Jacobsen, D.R.; Zech, D.J.

    1988-01-01

    A reference phantom for computer tomography employs a flexible member with means for urging the flexible member into contact along the curved surface of the lumbar region of a human patient. In one embodiment, the reference phantom is pre-curved in an arc greater than required. Pressure from the weight of a patient laying upon the reference phantom is effective for straightening out the curvature sufficiently to achieve substantial contact along the lumbar region. The curvature of the reference phantom may be additionally distorted by a resilient pad between the resilient phantom and a table for urging it into contact with the lumbar region. In a second embodiment of the invention, a flexible reference phantom is disposed in a slot in the top of a resilient cushion. The resilient cushion and reference phantom may be enclosed in a flexible container. A partially curved reference phantom in a slot in a resilient cushion is also contemplated. (author)

  5. Evolution of dosimetric phantoms

    International Nuclear Information System (INIS)

    Reddy, A.R.

    2010-01-01

    In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

  6. Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data

    International Nuclear Information System (INIS)

    Kiarashi, Nooshin; Nolte, Adam C.; Sturgeon, Gregory M.; Ghate, Sujata V.; Segars, William P.; Nolte, Loren W.; Samei, Ehsan

    2015-01-01

    Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated by high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power

  7. Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data

    Energy Technology Data Exchange (ETDEWEB)

    Kiarashi, Nooshin [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Nolte, Adam C. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Sturgeon, Gregory M.; Ghate, Sujata V. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Segars, William P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Nolte, Loren W. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States); and others

    2015-07-15

    Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated by high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power

  8. Material-Dependent Implant Artifact Reduction Using SEMAC-VAT and MAVRIC: A Prospective MRI Phantom Study.

    Science.gov (United States)

    Filli, Lukas; Jud, Lukas; Luechinger, Roger; Nanz, Daniel; Andreisek, Gustav; Runge, Val M; Kozerke, Sebastian; Farshad-Amacker, Nadja A

    2017-06-01

    The aim of this study was to compare the degree of artifact reduction in magnetic resonance imaging achieved with slice encoding for metal artifact correction (SEMAC) in combination with view angle tilting (VAT) and multiacquisition variable resonance image combination (MAVRIC) for standard contrast weightings and different metallic materials. Four identically shaped rods made of the most commonly used prosthetic materials (stainless steel, SS; titanium, Ti; cobalt-chromium-molybdenum, CoCr; and oxidized zirconium, oxZi) were scanned at 3 T. In addition to conventional fast spin-echo sequences, metal artifact reduction sequences (SEMAC-VAT and MAVRIC) with varying degrees of artifact suppression were applied at different contrast weightings (T1w, T2w, PDw). Two independent readers measured in-plane and through-plane artifacts in a standardized manner. In addition, theoretical frequency-offset and frequency-offset-gradient maps were calculated. Interobserver agreement was assessed using intraclass correlation coefficient. Interobserver agreement was almost perfect (intraclass correlation coefficient, 0.86-0.99). Stainless steel caused the greatest artifacts, followed by CoCr, Ti, and oxZi regardless of the imaging sequence. While for Ti and oxZi rods scanning with weak SEMAC-VAT showed some advantage, for SS and CoCr, higher modes of SEMAC-VAT or MAVRIC were necessary to achieve artifact reduction. MAVRIC achieved better artifact reduction than SEMAC-VAT at the cost of longer acquisition times. Simulations matched well with the apparent geometry of the frequency-offset maps. For Ti and oxZi implants, weak SEMAC-VAT may be preferred as it is faster and produces less artifact than conventional fast spin-echo. Medium or strong SEMAC-VAT or MAVRIC modes are necessary for significant artifact reduction for SS and CoCr implants.

  9. Phantom cosmologies and fermions

    International Nuclear Information System (INIS)

    Chimento, Luis P; Forte, Monica; Devecchi, Fernando P; Kremer, Gilberto M

    2008-01-01

    Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the 'phantomization' process exhibits a new class of possible accelerated regimes. As an application we analyze the cosmological constant group for a fermionic seed fluid

  10. 21. Phantom pain.

    NARCIS (Netherlands)

    Wolff, A.P.; Vanduynhoven, E.; Kleef, M. van; Huygen, F.; Pope, J.E.; Mekhail, N.

    2011-01-01

    Phantom pain is pain caused by elimination or interruption of sensory nerve impulses by destroying or injuring the sensory nerve fibers after amputation or deafferentation. The reported incidence of phantom limb pain after trauma, injury or peripheral vascular diseases is 60% to 80%. Over half the

  11. Fabrication and characterization of a 3-D non-homogeneous tissue-like mouse phantom for optical imaging

    Science.gov (United States)

    Avtzi, Stella; Zacharopoulos, Athanasios; Psycharakis, Stylianos; Zacharakis, Giannis

    2013-11-01

    In vivo optical imaging of biological tissue not only requires the development of new theoretical models and experimental procedures, but also the design and construction of realistic tissue-mimicking phantoms. However, most of the phantoms available currently in literature or the market, have either simple geometrical shapes (cubes, slabs, cylinders) or when realistic in shape they use homogeneous approximations of the tissue or animal under investigation. The goal of this study is to develop a non-homogeneous realistic phantom that matches the anatomical geometry and optical characteristics of the mouse head in the visible and near-infrared spectral range. The fabrication of the phantom consisted of three stages. Initially, anatomical information extracted from either mouse head atlases or structural imaging modalities (MRI, XCT) was used to design a digital phantom comprising of the three main layers of the mouse head; the brain, skull and skin. Based on that, initial prototypes were manufactured by using accurate 3D printing, allowing complex objects to be built layer by layer with sub-millimeter resolution. During the second stage the fabrication of individual molds was performed by embedding the prototypes into a rubber-like silicone mixture. In the final stage the detailed phantom was constructed by loading the molds with epoxy resin of controlled optical properties. The optical properties of the resin were regulated by using appropriate quantities of India ink and intralipid. The final phantom consisted of 3 layers, each one with different absorption and scattering coefficient (μa,μs) to simulate the region of the mouse brain, skull and skin.

  12. Individual virtual phantom reconstruction for organ dosimetry based on standard available phantoms

    International Nuclear Information System (INIS)

    Babapour Mofrad, F.; Aghaeizadeh Zoroofi, R.; Abbaspour Tehran Fard, A.; Akhlaghpoor, Sh.; Chen, Y. W.; Sato, Y.

    2010-01-01

    In nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. Monte Carlo Simulation and phantoms have been used in many works before. The shape, size and volume In organs are varied, and this variation will produce error in dose calculation if no correction is applied. Materials and Methods: A computational framework for constructing individual phantom for dosimetry was performed on five liver CT scan data sets of Japanese normal individuals. The Zubal phantom was used as an original phantom to be adjusted by each individual data set. This registration was done by Spherical Harmonics and Thin-Plate Spline methods. Hausdorff distance was calculated for each case. Results: Result of Hausdorff distance for five lndividual phantoms showed that before registration ranged from 140.9 to 192.1, and after registration it changed to 52.5 to 76.7. This was caused by Index similarity ranged from %56.4 to %70.3. Conclusion: A new and automatic three-dimensional (3D) phantom construction approach was-suggested for individual internal dosimetry simulation via Spherical Harmonics and Thin-Plate Spline methods. The results showed that the Individual comparable phantom can be calculated with acceptable accuracy using geometric registration. This method could be used for race-specific statistical phantom modeling with major application in nuclear medicine for absorbed dose calculation.

  13. Development of a physical 3D anthropomorphic breast phantom

    Energy Technology Data Exchange (ETDEWEB)

    Carton, Ann-Katherine; Bakic, Predrag; Ullberg, Christer; Derand, Helen; Maidment, Andrew D. A. [Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States); XCounter AB, Svaerdvaegen 11, SE-182 33 Danderyd (Sweden); Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States)

    2011-02-15

    Purpose: Develop a technique to fabricate a 3D anthropomorphic breast phantom with known ground truth for image quality assessment of 2D and 3D breast x-ray imaging systems. Methods: The phantom design is based on an existing computer model that can generate breast voxel phantoms of varying composition, size, and shape. The physical phantom is produced in two steps. First, the portion of the voxel phantom consisting of the glandular tissue, skin, and Cooper's ligaments is separated into sections. These sections are then fabricated by high-resolution rapid prototyping using a single material with 50% glandular equivalence. The remaining adipose compartments are then filled using an epoxy-based resin (EBR) with 100% adipose equivalence. The phantom sections are stacked to form the physical anthropomorphic phantom. Results: The authors fabricated a prototype phantom corresponding to a 450 ml breast with 45% dense tissue, deformed to a 5 cm compressed thickness. Both the rapid prototype (RP) and EBR phantom materials are radiographically uniform. The coefficient of variation (CoV) of the relative attenuation between RP and EBR phantom samples was <1% and the CoV of the signal intensity within RP and EBR phantom samples was <1.5% on average. Digital mammography and reconstructed digital breast tomosynthesis images of the authors' phantom were reviewed by two radiologists; they reported that the images are similar in appearance to clinical images, noting there are still artifacts from air bubbles in the EBR. Conclusions: The authors have developed a technique to produce 3D anthropomorphic breast phantoms with known ground truth, yielding highly realistic x-ray images. Such phantoms may serve both qualitative and quantitative performance assessments for 2D and 3D breast x-ray imaging systems.

  14. Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

    International Nuclear Information System (INIS)

    Chatelin, Simon; Bernal, Miguel; Deffieux, Thomas; Papadacci, Clément; Nahas, Amir; Boccara, Claude; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu; Flaud, Patrice

    2014-01-01

    Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305–11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original multimodality imaging characterization of this new transverse isotropic (TI) PVA hydrogel. Multiple properties were investigated using a large variety of techniques at different scales compared with an isotropic PVA hydrogel undergoing similar imaging and rheology protocols. The anisotropic mechanical (dynamic and static) properties were studied using supersonic shear wave imaging technique, full-field optical coherence tomography (FFOCT) strain imaging and classical linear rheometry using dynamic mechanical analysis. The anisotropic optical and ultrasonic spatial coherence properties were measured by FFOCT volumetric imaging and backscatter tensor imaging, respectively. Correlation of mechanical and optical properties demonstrates the complementarity of these techniques for the study of anisotropy on a multi-scale range as well as the potential of this TI phantom as fibrous tissue-mimicking phantom for shear wave elastographic applications. (paper)

  15. Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

    Science.gov (United States)

    Chatelin, Simon; Bernal, Miguel; Deffieux, Thomas; Papadacci, Clément; Flaud, Patrice; Nahas, Amir; Boccara, Claude; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

    2014-11-01

    Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305-11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original multimodality imaging characterization of this new transverse isotropic (TI) PVA hydrogel. Multiple properties were investigated using a large variety of techniques at different scales compared with an isotropic PVA hydrogel undergoing similar imaging and rheology protocols. The anisotropic mechanical (dynamic and static) properties were studied using supersonic shear wave imaging technique, full-field optical coherence tomography (FFOCT) strain imaging and classical linear rheometry using dynamic mechanical analysis. The anisotropic optical and ultrasonic spatial coherence properties were measured by FFOCT volumetric imaging and backscatter tensor imaging, respectively. Correlation of mechanical and optical properties demonstrates the complementarity of these techniques for the study of anisotropy on a multi-scale range as well as the potential of this TI phantom as fibrous tissue-mimicking phantom for shear wave elastographic applications.

  16. Deformable and durable phantoms with controlled density of scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Bisaillon, Charles-Etienne; Lamouche, Guy; Dufour, Marc; Monchalin, Jean-Pierre [Industrial Materials Institute, National Research Council Canada, 75 de Mortagne, Boucherville, Quebec J4B 6Y4 (Canada); Maciejko, Romain [Optoelectronics Laboratory, Engineering Physics, Ecole Polytechnique de Montreal, PO Box 6079, Station ' Centre-ville' Montreal, Quebec H3C 3A7 (Canada)], E-mail: charles-etienne.bisaillon@cnrc-nrc.gc.ca, E-mail: guy.lamouche@cnrc-nrc.gc.ca, E-mail: marc.dufour@cnrc-nrc.gc.ca, E-mail: jean-pierre.monchalin@cnrc-nrc.gc.ca, E-mail: romain.maciejko@polytml.ca

    2008-07-07

    We have developed deformable and durable optical tissue phantoms with a simple and well-defined microstructure including a novel combination of scatterers and a matrix material. These were developed for speckle and elastography investigations in optical coherence tomography, but should prove useful in many other fields. We present in detail the fabrication process which involves embedding silica microspheres in a silicone matrix. We also characterize the resulting phantoms with scanning electron microscopy and optical measurements. To our knowledge, no such phantoms were proposed in the literature before. Our technique has a wide range of applicability and could also be adapted to fabricate phantoms with various optical and mechanical properties. (note)

  17. Influence of Manufacturing Processes on the Performance of Phantom Lungs

    International Nuclear Information System (INIS)

    Traub, Richard J.

    2008-01-01

    Chest counting is an important tool for estimating the radiation dose to individuals who have inhaled radioactive materials. Chest counting systems are calibrated by counting the activity in the lungs of phantoms where the activity in the phantom lungs is known. In the United States a commonly used calibration phantom was developed at the Lawrence Livermore National Laboratory and is referred to as the Livermore Torso Phantom. An important feature of this phantom is that the phantom lungs can be interchanged so that the counting system can be challenged by different combinations of radionuclides and activity. Phantom lungs are made from lung tissue substitutes whose constituents are foaming plastics and various adjuvants selected to make the lung tissue substitute similar to normal healthy lung tissue. Some of the properties of phantom lungs cannot be readily controlled by phantom lung manufacturers. Some, such as density, are a complex function of the manufacturing process, while others, such as elemental composition of the bulk plastic are controlled by the plastics manufacturer without input, or knowledge of the phantom manufacturer. Despite the fact that some of these items cannot be controlled, they can be measured and accounted for. This report describes how manufacturing processes can influence the performance of phantom lungs. It is proposed that a metric that describes the brightness of the lung be employed by the phantom lung manufacturer to determine how well the phantom lung approximates the characteristics of a human lung. For many purposes, the linear attenuation of the lung tissue substitute is an appropriate surrogate for the brightness

  18. The Phantom Menace

    DEFF Research Database (Denmark)

    Vium, Christian

    2013-01-01

    as a phantom menace, which asserts itself through a form of omnipresent fear, nurtured by an inherent opaqueness. As this fundamental fear progressively permeates the nomadic landscape, it engenders a recasting of mobile strategies among the nomadic pastoralist groups who inhabit the interstitial desert spaces....

  19. Phantom crash confirms models

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    To test computer models of how a nuclear reactor's containment building would fare if an airplane crashed into it, the Muto Institute in Tokyo sponsored a 3.2 million dollar project at Sandia National Laboratory to slam an F-4 Phantom jet into a 500 ton concrete wall. The results showed that the computer calculations were accurate

  20. Determination of photon conversion factors relating exposure and dose for several extremity phantom designs

    International Nuclear Information System (INIS)

    Roberson, P.L.; Eichner, F.N.; Reece, W.D.

    1986-09-01

    This report presents the results of measurements of dosimetric properties of simple extremity phantoms suitable for use in extremity dosimeter performance testing. Two sizes of phantoms were used in this study. One size represented the forearm or lower leg and the other size represented the finger or toe. For both phantom sizes, measurements were performed on solid plastic phantoms and on phantoms containing simulated bone material to determine the effect of backscattered radiations from the bone on the surface dose. Exposure-to-dose conversion factors (C/sub x/ factors) were determined for photon energies ranging from 16 to 1250 keV (average for 60 Co). The effect of the presence of a phantom was also measured for a 90 Sr/ 90 Y source. Significant differences in the measured C/sub x/ factors were found among the phantoms investigated. The factors for the finger-sized phantoms were uniformly less than for the arm-sized phantoms

  1. Transorbital therapy delivery: phantom testing

    Science.gov (United States)

    Ingram, Martha-Conley; Atuegwu, Nkiruka; Mawn, Louise; Galloway, Robert L.

    2011-03-01

    We have developed a combined image-guided and minimally invasive system for the delivery of therapy to the back of the eye. It is composed of a short 4.5 mm diameter endoscope with a magnetic tracker embedded in the tip. In previous work we have defined an optimized fiducial placement for accurate guidance to the back of the eye and are now moving to system testing. The fundamental difficulty in testing performance is establishing a target in a manner which closely mimics the physiological task. We have to have a penetrable material which obscures line of sight, similar to the orbital fat. In addition we need to have some independent measure of knowing when a target has been reached to compare to the ideal performance. Lastly, the target cannot be rigidly attached to the skull phantom since the optic nerve lies buried in the orbital fat. We have developed a skull phantom with white cloth stellate balls supporting a correctly sized globe. Placed in the white balls are red, blue, orange and yellow balls. One of the colored balls has been soaked in barium to make it bright on CT. The user guides the tracked endoscope to the target as defined by the images and tells us its color. We record task accuracy and time to target. We have tested this with 28 residents, fellows and attending physicians. Each physician performs the task twice guided and twice unguided. Results will be presented.

  2. A paper sheet phantom for scintigraphic planar imaging. Usefulness of pouch-laminated paper source

    International Nuclear Information System (INIS)

    Takaki, Akihiro; Soma, Tsutomu; Murase, Kenya; Teraoka, Satomi; Murakami, Tomonori; Kojima, Akihiro; Matsumoto, Masanori

    2007-01-01

    In order to perform experimental measurements for evaluation of imaging device's performance, data acquisition technique, and clinical images on scintigraphic imaging, many kinds of phantoms are employed. However, since these materials are acrylic and plastic, the thickness and quality of those materials cause attenuation and scatter in itself. We developed a paper sheet phantom sealed with a pouch laminator, which can be a true radioactive source in air. In this study, the paper sheet phantom was compared to the acrylic liver phantom, with the thickness of 2 cm, which is commercially available. The results showed that although some scatter counts were contained within the image of the acrylic liver phantom, there were few scattered photons in the paper sheet phantom image. Furthermore, this laminated paper sheet phantom made handling of the source and its waste easier. If the paper sheet phantom will be designed more sophisticatedly, it becomes a useful tool for planar imaging experiments. (author)

  3. Phantom pain after eye amputation

    DEFF Research Database (Denmark)

    Rasmussen, Marie L R; Prause, Jan U; Toft, Peter B

    2011-01-01

    Purpose: To characterize the quality of phantom pain, its intensity and frequency following eye amputation. Possible triggers and relievers of phantom pain are investigated. Methods: The hospital database was searched using surgery codes for patients who received ocular evisceration, enucleation...... was conducted by a trained interviewer. Results: Of the 173 patients in the study, 39 experienced phantom pain. The median age of patients who had experienced phantom pain was 45 years (range: 19–88). Follow-up time from eye amputation to participation in the investigation was 4 years (range: 2–46). Phantom...... scale, ranging from 0 to 100, was 36 (range: 1–89). One-third of the patients experienced phantom pain every day. Chilliness, windy weather and psychological stress/fatigue were the most commonly reported triggers for pain. Conclusions: Phantom pain after eye amputation is relatively common. The pain...

  4. Enceladus' 101 Geysers: Phantoms? Hardly

    Science.gov (United States)

    Porco, C.; Nimmo, F.; DiNino, D.

    2015-12-01

    The discovery by the Cassini mission of present-day geysering activity capping the southern hemisphere of Saturn's moon Enceladus (eg, Porco, C. C. et al. Science 311, 1393, 2006) and sourced within a subsurface body of liquid water (eg, Postberg, F. et al. Nature 459, 1098, 2009; Porco, C.C. et al. AJ 148, 45, 2014, hereafter PEA], laced with organic compounds (eg, Waite, J.H. et al. Science 311, 1419, 2006), has been a significant one, with far-reaching astrobiological implications. In an extensive Cassini imaging survey of the moon's south polar terrain (SPT), PEA identified 101 distinct, narrow jets of small icy particles erupting, with varying strengths, from the four major fractures crossing the SPT. A sufficient spread in stereo angles of the 107 images used in that work allowed (in some cases, many) pair-wise triangulations to be computed; precise surface locations were derived for 98 jets. Recently, it has been claimed (Spitale, J.N. et al. Nature 521, 57, 2015) that the majority of the geysers are not true discrete jets, but are "phantoms" that appear in shallow-angle views of a dense continuous curtain of material with acute bends in it. These authors also concluded that the majority of the eruptive material is not in the form of jets but in the form of fissure-style 'curtain' eruptions. We argue below the contrary, that because almost all the moon's geysers were identified by PEA using multiple images with favorable viewing geometries, the vast majority of them, and likely all, are discrete jets. Specifically, out of 98 jets, no fewer than 90 to 95 were identified with viewing geometries that preclude the appearance of phantoms. How the erupting solids (i.e., icy particles) that are seen in Cassini images are partitioned between jets and inter-jet curtains is still an open question.

  5. Speckle tracking in a phantom and feature-based tracking in liver in the presence of respiratory motion using 4D ultrasound

    International Nuclear Information System (INIS)

    Harris, Emma J; Miller, Naomi R; Bamber, Jeffrey C; Symonds-Tayler, J Richard N; Evans, Philip M

    2010-01-01

    We have evaluated a 4D ultrasound-based motion tracking system developed for tracking of abdominal organs during therapy. Tracking accuracy and precision were determined using a tissue-mimicking phantom, by comparing tracked motion with known 3D sinusoidal motion. The feasibility of tracking 3D liver motion in vivo was evaluated by acquiring 4D ultrasound data from four healthy volunteers. For two of these volunteers, data were also acquired whilst simultaneously measuring breath flow using a spirometer. Hepatic blood vessels, tracked off-line using manual tracking, were used as a reference to assess, in vivo, two types of automated tracking algorithm: incremental (from one volume to the next) and non-incremental (from the first volume to each subsequent volume). For phantom-based experiments, accuracy and precision (RMS error and SD) were found to be 0.78 mm and 0.54 mm, respectively. For in vivo measurements, mean absolute distance and standard deviation of the difference between automatically and manually tracked displacements were less than 1.7 mm and 1 mm respectively in all directions (left-right, anterior-posterior and superior-inferior). In vivo non-incremental tracking gave the best agreement. In both phantom and in vivo experiments, tracking performance was poorest for the elevational component of 3D motion. Good agreement between automatically and manually tracked displacements indicates that 4D ultrasound-based motion tracking has potential for image guidance applications in therapy.

  6. Characterization of the materials used in the construction of a physical phantom for calibration of {sup 18}F-FDG internal dosimetry system

    Energy Technology Data Exchange (ETDEWEB)

    Vital, Katia D.; Mendes, Bruno M.; Fonseca, Telma C.F.; Silva, Teógenes A. da, E-mail: katiadvitall@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte - MG (Brazil)

    2017-07-01

    The Internal Dosimetry Laboratory (LDI) of the Nuclear Technology Development Center (CDTN) in Minas Gerais, Brazil, is responsible for the routine monitoring of Occupationally Exposed Individuals (OEIs) to {sup 18}F-FDG and other radiopharmaceuticals produced at CDTN. The monitoring system is usually calibrated using a physical head simulator, since {sup 18}F is usually incorporated into the brain at the time of contamination. However, the geometry of the brain is not adequately represented by the latex pocket, which does not fill the entire volume of the volume skull. In this study, the characterization of the materials regarding the composition, density and attenuation coefficient of the materials used in the production of the new physical head simulator was carried out. An equivalent tissue material containing 97% water, 2.5% agar, 0.5% urea and 8 MBq of {sup 18}F-FDG was produced, the interior of the skull was filled with the material. After solidification, experimental measurements were performed on the NaI(Tl) 3 {sup x}3{sup s}cintillation detector, the density of the simulant material was determined by the flotation method and the attenuation coefficient of the XCOM database software provided by NIST. It was concluded that the PVC skull has acceptable characteristics to simulate a human skull in {sup 18}F-FDG internal dosimetry. The agar gel was shown to be a stable material capable of modeling different geometries and simulating the incorporation of {sup 18}F-FDG into the brain. (author)

  7. Characterization of the materials used in the construction of a physical phantom for calibration of 18F-FDG internal dosimetry system

    International Nuclear Information System (INIS)

    Vital, Katia D.; Mendes, Bruno M.; Fonseca, Telma C.F.; Silva, Teógenes A. da

    2017-01-01

    The Internal Dosimetry Laboratory (LDI) of the Nuclear Technology Development Center (CDTN) in Minas Gerais, Brazil, is responsible for the routine monitoring of Occupationally Exposed Individuals (OEIs) to 18 F-FDG and other radiopharmaceuticals produced at CDTN. The monitoring system is usually calibrated using a physical head simulator, since 18 F is usually incorporated into the brain at the time of contamination. However, the geometry of the brain is not adequately represented by the latex pocket, which does not fill the entire volume of the volume skull. In this study, the characterization of the materials regarding the composition, density and attenuation coefficient of the materials used in the production of the new physical head simulator was carried out. An equivalent tissue material containing 97% water, 2.5% agar, 0.5% urea and 8 MBq of 18 F-FDG was produced, the interior of the skull was filled with the material. After solidification, experimental measurements were performed on the NaI(Tl) 3 x 3 s cintillation detector, the density of the simulant material was determined by the flotation method and the attenuation coefficient of the XCOM database software provided by NIST. It was concluded that the PVC skull has acceptable characteristics to simulate a human skull in 18 F-FDG internal dosimetry. The agar gel was shown to be a stable material capable of modeling different geometries and simulating the incorporation of 18 F-FDG into the brain. (author)

  8. Phantom breast syndrome

    Directory of Open Access Journals (Sweden)

    Ramesh

    2009-01-01

    Full Text Available Phantom breast syndrome is a type of condition in which patients have a sensation of residual breast tissue and can include both non-painful sensations as well as phantom breast pain. The incidence varies in different studies, ranging from approximately 30% to as high as 80% of patients after mastectomy. It seriously affects quality of life through the combined impact of physical disability and emotional distress. The breast cancer incidence rate in India as well as Western countries has risen in recent years while survival rates have improved; this has effectively increased the number of women for whom post-treatment quality of life is important. In this context, chronic pain following treatment for breast cancer surgery is a significantly under-recognized and under-treated problem. Various types of chronic neuropathic pain may arise following breast cancer surgery due to surgical trauma. The cause of these syndromes is damage to various nerves during surgery. There are a number of assumed factors causing or perpetuating persistent neuropathic pain after breast cancer surgery. Most well-established risk factors for developing phantom breast pain and other related neuropathic pain syndromes are severe acute postoperative pain and greater postoperative use of analgesics. Based upon current evidence, the goals of prophylactic strategies could first target optimal peri-operative pain control and minimizing damage to nerves during surgery. There is some evidence that chronic pain and sensory abnormalities do decrease over time. The main group of oral medications studied includes anti-depressants, anticonvulsants, opioids, N-methyl-D-asparate receptor antagonists, mexilitine, topical lidocaine, cannabinoids, topical capsaicin and glysine antagonists. Neuromodulation techniques such as motor cortex stimulation, spinal cord stimulation, and intrathecal drug therapies have been used to treat various neuropathic pain syndromes.

  9. The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

    Science.gov (United States)

    Taylor, Jonathan C; Vennart, Nicholas; Negus, Ian; Holmes, Robin; Bandmann, Oliver; Lo, Christine; Fenner, John

    2018-03-01

    The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

  10. Development of a phantom to test fully automated breast density software – A work in progress

    International Nuclear Information System (INIS)

    Waade, G.G.; Hofvind, S.; Thompson, J.D.; Highnam, R.; Hogg, P.

    2017-01-01

    Objectives: Mammographic density (MD) is an independent risk factor for breast cancer and may have a future role for stratified screening. Automated software can estimate MD but the relationship between breast thickness reduction and MD is not fully understood. Our aim is to develop a deformable breast phantom to assess automated density software and the impact of breast thickness reduction on MD. Methods: Several different configurations of poly vinyl alcohol (PVAL) phantoms were created. Three methods were used to estimate their density. Raw image data of mammographic images were processed using Volpara to estimate volumetric breast density (VBD%); Hounsfield units (HU) were measured on CT images; and physical density (g/cm 3 ) was calculated using a formula involving mass and volume. Phantom volume versus contact area and phantom volume versus phantom thickness was compared to values of real breasts. Results: Volpara recognized all deformable phantoms as female breasts. However, reducing the phantom thickness caused a change in phantom density and the phantoms were not able to tolerate same level of compression and thickness reduction experienced by female breasts during mammography. Conclusion: Our results are promising as all phantoms resulted in valid data for automated breast density measurement. Further work should be conducted on PVAL and other materials to produce deformable phantoms that mimic female breast structure and density with the ability of being compressed to the same level as female breasts. Advances in knowledge: We are the first group to have produced deformable phantoms that are recognized as breasts by Volpara software. - Highlights: • Several phantoms of different configurations were created. • Three methods to assess phantom density were implemented. • All phantoms were identified as breasts by the Volpara software. • Reducing phantom thickness caused a change in phantom density.

  11. Design of a multimodal ({sup 1}H/{sup 23}Na MR/CT) anthropomorphic thorax phantom

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Wiebke; Lietzmann, Florian; Schad, Lothar R.; Zoellner, Frank G. [Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine

    2017-08-01

    This work proposes a modular, anthropomorphic MR and CT thorax phantom that enables the comparison of experimental studies for quantitative evaluation of deformable, multimodal image registration algorithms and realistic multi-nuclear MR imaging techniques. A human thorax phantom was developed with insertable modules representing lung, liver, ribs and additional tracking spheres. The quality of human tissue mimicking characteristics was evaluated for {sup 1}H and {sup 23}Na MR as well as CT imaging. The position of landmarks in the lung lobes was tracked during CT image acquisition at several positions during breathing cycles. {sup 1}H MR measurements of the liver were repeated after seven months to determine long term stability. The modules possess HU, T{sub 1} and T{sub 2} values comparable to human tissues (lung module: -756 ± 148 HU, artificial ribs: 218 ± 56 HU (low CaCO{sub 3} concentration) and 339 ± 121 (high CaCO{sub 3} concentration), liver module: T{sub 1} = 790 ± 28 ms, T{sub 2} = 65 ± 1 ms). Motion analysis showed that the landmarks in the lung lobes follow a 3D trajectory similar to human breathing motion. The tracking spheres are well detectable in both CT and MRI. The parameters of the tracking spheres can be adjusted in the following ranges to result in a distinct signal: HU values from 150 to 900 HU, T{sub 1} relaxation time from 550 ms to 2000 ms, T{sub 2} relaxation time from 40 ms to 200 ms. The presented anthropomorphic multimodal thorax phantom fulfills the demands of a simple, inexpensive system with interchangeable components. In future, the modular design allows for complementing the present set up with additional modules focusing on specific research targets such as perfusion studies, {sup 23}Na MR quantification experiments and an increasing level of complexity for motion studies.

  12. Regional heating patterns of RF hyperthermia applicators in phantoms

    International Nuclear Information System (INIS)

    Kantor, G.; Ruggera, P.S.; Samulski, T.V.

    1984-01-01

    An elliptical phantom (20 cm by 30 cm cross-section and 40 cm long) with a 1 cm fat layer filled with muscle material was used to compare the induced heating patterns of the NCDRH helical coil, a Henry Medical Magnetrode coil, both with a diameter of 35.6 cm, and the BSD Annular Phased Array System (APAS). Temperature profiles were taken in the midplane cross-sectional slice along the major and minor axes of the phantom. These profiles were measured with a Vitek thermistor probe and the associated specific absorption rates (SAR) were determined from this data. SAR curves for each applicator were obtained along the major and minor axes of the phantom. The depths of heating of the Magnetrode applicator are considerably smaller than those for the helical applicator. Heating patterns for the APAS can be highly variable and asymmetric depending on the frequency of operation and the location of the phantom within the APAS aperture. While the APAS requires a water bolus for good coupling, the NCDRH and Magnetrode coils need only to be air coupled for good phantom coupling. Both the helical applicator and APAS can provide significant heating in the central region of the phantom. However, the heating of the helical coil does not critically depend on the phantom loading

  13. Development of realistic chest phantom for calibration of in-vivo plutonium counting facilities

    International Nuclear Information System (INIS)

    Shirotani, Takashi

    1987-06-01

    We have developed realistic chest phantom with removable model organs. The phantom is a torso and is terminated just above the femoral region. Tissue equivalent materials used in the phantom have been made of polyurethane with different amounts of ester of phosphoric acid, in order to simulate human soft tissues such as muscle, muscle-adipose mixtures and cartilage. Lung simulant has been made of foamed polyurethane. Capsulized small sources can be inserted into the holes, drilled in each sliced section of the model organ. Counting efficiencies, obtained with a pair of 12 cm diameter phoswich detectors set above the phantom chest, are 0.195 cpm/nCi for Pu-239 and 44.07 cpm/nCi for Am-241, respectively. The results agree well with efficiencies obtained with IAEA-Phantom. We conclude that the phantom can be used as a standard phantom for the calibration of Pu chest counting equipment. (author)

  14. Determination of optimum filter in myocardial SPECT: A phantom study

    International Nuclear Information System (INIS)

    Takavar, A.; Shamsipour, Gh.; Sohrabi, M.; Eftekhari, M.

    2004-01-01

    Background: In myocardial perfusion SPECT images are degraded by photon attenuation, the distance-dependent collimator, detector response and photons scatter. Filters greatly affect quality of nuclear medicine images. Materials and Methods: A phantom simulating heart left ventricle was built. About 1mCi of 99m Tc was injected into the phantom. Images was taken from this phantom. Some filters including Parzen, Hamming, Hanning, Butter worth and Gaussian were exerted on the phantom images. By defining some criteria such as contrast, signal to noise ratio, and defect size detectability, the best filter can be determined. Results: 0.325 Nyquist frequency and 0.5 nq was obtained as the optimum cut off frequencies respectively for hamming and handing filters. Order 11, cut off 0.45 Nq and order 20 cut off 0.5 Nq obtained optimum respectively for Butter worth and Gaussian filters. Conclusion: The optimum member of every filter's family was obtained

  15. BOMAB phantom manufacturing quality assurance study using Monte Carlo computations

    International Nuclear Information System (INIS)

    Mallett, M.W.

    1994-01-01

    Monte Carlo calculations have been performed to assess the importance of and quantify quality assurance protocols in the manufacturing of the Bottle-Manikin-Absorption (BOMAB) phantom for calibrating in vivo measurement systems. The parameters characterizing the BOMAB phantom that were examined included height, fill volume, fill material density, wall thickness, and source concentration. Transport simulation was performed for monoenergetic photon sources of 0.200, 0.662, and 1,460 MeV. A linear response was observed in the photon current exiting the exterior surface of the BOMAB phantom due to variations in these parameters. Sensitivity studies were also performed for an in vivo system in operation at the Pacific Northwest Laboratories in Richland, WA. Variations in detector current for this in vivo system are reported for changes in the BOMAB phantom parameters studied here. Physical justifications for the observed results are also discussed

  16. Atypical Odontalgia (Phantom Tooth Pain)

    Science.gov (United States)

    ... atypical facial pain, phantom tooth pain, or neuropathic orofacial pain, is characterized by chronic pain in a tooth ... such as a specialist in oral medicine or orofacial pain. The information contained in this monograph is for ...

  17. Shear wave elastography using ultrasound: effects of anisotropy and stretch stress on a tissue phantom and reactive lymph nodes in the neck

    Directory of Open Access Journals (Sweden)

    Ha Young Lee

    2017-01-01

    Full Text Available Purpose The purpose of this study was to evaluate how the anisotropy and the static stretch stress of the cervical musculature influence the measured shear modulus in a tissue-mimicking phantom and in cervical lymph nodes in vivo by using shear wave elastography (SWE. Methods SWE was performed on a phantom using a pig muscle and on the middle jugular cervical lymph nodes in six volunteers. Tissue elasticity was quantified using the shear modulus and a supersonic shear wave imaging technique. For the phantom study, first, the optimal depth for measurement was determined, and then, SWE was performed in parallel and perpendicular to the muscle fiber orientation with and without strain stress. For the in vivo study, SWE was performed on the cervical lymph nodes in parallel and perpendicular to the sternocleidomastoid muscle fiber direction with and without neck stretching. The mean values of the shear modulus (meanSM were then analyzed. Results In the phantom study, the measured depth significantly influenced the meanSM with a sharp decrease at the depth of 1.5 cm (P<0.001. Strain stress increased the meanSM, irrespective of the muscle fiber orientation (P<0.001. In the in vivo study, the meanSM values obtained in parallel to the muscle fiber orientation were greater than those obtained perpendicular to the fiber orientation, irrespective of the stretch stress (P<0.001. However, meanSM was affected significantly by the stretch stress parallel to the muscle fiber orientation (P<0.001. Conclusion The anisotropic nature of the cervical musculature and the applied stretch stress explain the variability of the SWE measurements and should be identified before applying SWE for the interpretation of the measured shear modulus values.

  18. Polyvinyl chloride plastisol breast phantoms for ultrasound imaging.

    Science.gov (United States)

    de Carvalho, Isabela Miller; De Matheo, Lucas Lobianco; Costa Júnior, José Francisco Silva; Borba, Cecília de Melo; von Krüger, Marco Antonio; Infantosi, Antonio Fernando Catelli; Pereira, Wagner Coelho de Albuquerque

    2016-08-01

    Ultrasonic phantoms are objects that mimic some features of biological tissues, allowing the study of their interactions with ultrasound (US). In the diagnostic-imaging field, breast phantoms are an important tool for testing performance and optimizing US systems, as well as for training medical professionals. This paper describes the design and manufacture of breast lesions by using polyvinyl chloride plastisol (PVCP) as the base material. Among the materials available for this study, PVCP was shown to be stable, durable, and easy to handle. Furthermore, it is a nontoxic, nonpolluting, and low-cost material. The breast's glandular tissue (image background) was simulated by adding graphite powder with a concentration of 1% to the base material. Mixing PVCP and graphite powder in differing concentrations allows one to simulate lesions with different echogenicity patterns (anechoic, hypoechoic, and hyperechoic). From this mixture, phantom materials were obtained with speed of sound varying from 1379.3 to 1397.9ms(-1) and an attenuation coefficient having values between 0.29 and 0.94dBcm(-1) for a frequency of 1MHz at 24°C. A single layer of carnauba wax was added to the lesion surface in order to evaluate its applicability for imaging. The images of the phantoms were acquired using commercial ultrasound equipment; a specialist rated the images, elaborating diagnoses representative of both benign and malignant lesions. The results indicated that it was possible to easily create a phantom by using low-cost materials, readily available in the market and stable at room temperature, as the basis of ultrasonic phantoms that reproduce the image characteristics of fatty breast tissue and typical lesions of the breast. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. An improved Virtual Torso phantom

    International Nuclear Information System (INIS)

    Kramer, Gary H; Crowley, Paul

    2000-01-01

    The virtual phantom that was previously designed by the Human Monitoring Laboratory had some limitations. It contained no sternum and the ribs extended all the way round the torso, whereas in reality the central part of the chest is covered with a mixture of cartilage (ribs) and bone (sternum). The ribs were located below the chest wall which added to the thickness of the chest wall. The lungs did not touch the inner surface of the chest wall along their length due to the differences in curvature between the ellipsoidal lungs and the ellipsoidal cylinder that defined the torso. As a result there was extra intervening tissue between the lungs and the chest wall. This was shown to have a noticeable effect on the simulation of low energy photons. The virtual phantom has been redesigned and comparison of measured and calculated counting efficiencies shows that it is a good representation of both of LLNL or JAERI at all photon energies measured. The redesigned virtual phantom agrees to within 11% of the torsos' counting efficiency over the energy range 17 - 240 keV. Before modification, the virtual phantom's counting efficiency was a of factor three lower at 17 keV and a factor of two lower at 20 keV; now it is within 5% at 17 keV and within 10% at 20 keV. This phantom can now be reliably used to simulate lung counting. The virtual phantom still contains no sternum and the ribs extend all the way round the torso, whereas in reality the central part of the chest is covered with cartilage (ribs) and bone (sternum). However, the above results indicate that this is not a major flaw in the design of the virtual phantom, as agreement between the Monte Carlo results and experimental data is good. (author)

  20. Liver phantom for quality control and training in nuclear medicine

    International Nuclear Information System (INIS)

    Lima Ferreira, Fernanda Carla; Nascimento Souza, Divanizia do

    2011-01-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256x256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  1. Liver phantom for quality control and training in nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Lima Ferreira, Fernanda Carla [Departamento de Fisica, Universidade Federal de Sergipe, Sao Cristovao, SE, 49100 000 (Brazil); Nascimento Souza, Divanizia do, E-mail: divanizi@ufs.br [Departamento de Fisica, Universidade Federal de Sergipe, Sao Cristovao, SE, 49100 000 (Brazil)

    2011-10-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256x256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  2. Liver phantom for quality control and training in nuclear medicine

    Science.gov (United States)

    Lima Ferreira, Fernanda Carla; Souza, Divanizia do Nascimento

    2011-10-01

    In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256×256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

  3. A methodology for developing anisotropic AAA phantoms via additive manufacturing.

    Science.gov (United States)

    Ruiz de Galarreta, Sergio; Antón, Raúl; Cazón, Aitor; Finol, Ender A

    2017-05-24

    An Abdominal Aortic Aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta at least 1.5 times its normal diameter. The criterion of maximum diameter is still used in clinical practice, although numerical studies have demonstrated the importance of biomechanical factors for rupture risk assessment. AAA phantoms could be used for experimental validation of the numerical studies and for pre-intervention testing of endovascular grafts. We have applied multi-material 3D printing technology to manufacture idealized AAA phantoms with anisotropic mechanical behavior. Different composites were fabricated and the phantom specimens were characterized by biaxial tensile tests while using a constitutive model to fit the experimental data. One composite was chosen to manufacture the phantom based on having the same mechanical properties as those reported in the literature for human AAA tissue; the strain energy and anisotropic index were compared to make this choice. The materials for the matrix and fibers of the selected composite are, respectively, the digital materials FLX9940 and FLX9960 developed by Stratasys. The fiber proportion for the composite is equal to 0.15. The differences between the composite behavior and the AAA tissue are small, with a small difference in the strain energy (0.4%) and a maximum difference of 12.4% in the peak Green strain ratio. This work represents a step forward in the application of 3D printing technology for the manufacturing of AAA phantoms with anisotropic mechanical behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Quantification of breast density using dual-energy mammography with liquid phantom calibration

    International Nuclear Information System (INIS)

    Lam, Alfonso R; Ding, Huanjun; Molloi, Sabee

    2014-01-01

    Breast density is a widely recognized potential risk factor for breast cancer. However, accurate quantification of breast density is a challenging task in mammography. The current use of plastic breast-equivalent phantoms for calibration provides limited accuracy in dual-energy mammography due to the chemical composition of the phantom. We implemented a breast-equivalent liquid phantom for dual-energy calibration in order to improve the accuracy of breast density measurement. To design these phantoms, three liquid compounds were chosen: water, isopropyl alcohol, and glycerol. Chemical compositions of glandular and adipose tissues, obtained from NIST database, were used as reference materials. Dual-energy signal of the liquid phantom at different breast densities (0% to 100%) and thicknesses (1 to 8 cm) were simulated. Glandular and adipose tissue thicknesses were estimated from a higher order polynomial of the signals. Our results indicated that the linear attenuation coefficients of the breast-equivalent liquid phantoms match those of the target material. Comparison between measured and known breast density data shows a linear correlation with a slope close to 1 and a non-zero intercept of 7%, while plastic phantoms showed a slope of 0.6 and a non-zero intercept of 8%. Breast density results derived from the liquid calibration phantoms showed higher accuracy than those derived from the plastic phantoms for different breast thicknesses and various tube voltages. We performed experimental phantom studies using liquid phantoms and then compared the computed breast density with those obtained using a bovine tissue model. The experimental data and the known values were in good correlation with a slope close to 1 (∼1.1). In conclusion, our results indicate that liquid phantoms are a reliable alternative for calibration in dual-energy mammography and better reproduce the chemical properties of the target material. (paper)

  5. SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

    International Nuclear Information System (INIS)

    Ehler, E; Higgins, P; Dusenbery, K

    2014-01-01

    Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom

  6. SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

    2014-06-15

    Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom.

  7. Construction of Chinese reference female phantom

    International Nuclear Information System (INIS)

    Sheng Yinxiangzi; Liu Lixing; Xia Xiaobin

    2013-01-01

    In this study, a Voxel-based Chinese Reference female Phantom (VCRP-woman) is developed from an individual female phantom which was based on high resolution cross-sectional color photographs. An in-house C ++ program was developed to adjust the phantom. Finally, a reference female phantom with have the same height, weighte and similar organs masses with the Chinese reference adult female data. The adjusted phantom is then imported to MCNPX to calculate the organs absorbed dose and effective dose conversion coefficients. Results are compared between VCRP-woman and the ICRP adult reference female phantom. (authors)

  8. Design, manufacture, and evaluation of an anthropomorphic pelvic phantom purpose-built for radiotherapy dosimetric intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, K. M.; Ebert, M. A.; Kron, T.; Howlett, S. J.; Cornes, D.; Hamilton, C. S.; Denham, J. W. [Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Physics, University of Newcastle, New South Wales 2308 (Australia); Department of Radiation Oncology, Sir Charles Gairdner Hospital, Western Australia, Australia and School of Physics, University of Western Australia, Western Australia 6009 (Australia); Department of Physical Sciences, Peter MacCallum Cancer Centre, Victoria 8006 (Australia); Australiasian College of Physical Scientists and Engineers in Medicine, Sydney, New South Wales 2020 (Australia); Trans-Tasman Radiation Oncology Group, Calvary Mater Newcastle, New South Wales 2298 (Australia); Heidelberg Repatriation Hospital, Victoria 3081 (Australia); Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Medicine and Population Health, University of Newcastle, New South Wales 2308 (Australia)

    2011-10-15

    Purpose: An anthropomorphic pelvic phantom was designed and constructed to meet specific criteria for multicenter radiotherapy dosimetric intercomparison. Methods: Three dimensional external and organ outlines were generated from a computed tomography image set of a male pelvis, forming the basis of design for an anatomically realistic phantom. Clinically relevant points of interest were selected throughout the dataset where point-dose values could be measured with thermoluminescence dosimeters and a small-volume ionization chamber. Following testing, three materials were selected and the phantom was manufactured using modern prototyping techniques into five separate coronal slices. Time lines and resource requirements for the phantom design and manufacture were recorded. The ability of the phantom to mimic the entire treatment chain was tested. Results: The phantom CT images indicated that organ densities and geometries were comparable to those of the original patient. The phantom proved simple to load for dosimetry and rapid to assemble. Due to heat release during manufacture, small air gaps and density heterogeneities were present throughout the phantom. The overall cost for production of the prototype phantom was comparable to other commercial anthropomorphic phantoms. The phantom was shown to be suitable for use as a ''patient'' to mimic the entire treatment chain for typical external beam radiotherapy for prostate and rectal cancer. Conclusions: The phantom constructed for the present study incorporates all characteristics necessary for accurate Level III intercomparison studies. Following use in an extensive Level III dosimetric comparison over a large time scale and geographic area, the phantom retained mechanical stability and did not show signs of radiation-induced degradation.

  9. Monte Carlo-based investigation of water-equivalence of solid phantoms at 137Cs energy

    International Nuclear Information System (INIS)

    Vishwakarma, Ramkrushna S.; Palani Selvam, T.; Sahoo, Sridhar; Mishra, Subhalaxmi; Chourasiya, Ghanshyam

    2013-01-01

    Investigation of solid phantom materials such as solid water, virtual water, plastic water, RW1, polystyrene, and polymethylmethacrylate (PMMA) for their equivalence to liquid water at 137 Cs energy (photon energy of 662 keV) under full scatter conditions is carried out using the EGSnrc Monte Carlo code system. Monte Carlo-based EGSnrc code system was used in the work to calculate distance-dependent phantom scatter corrections. The study also includes separation of primary and scattered dose components. Monte Carlo simulations are carried out using primary particle histories up to 5 x 10 9 to attain less than 0.3% statistical uncertainties in the estimation of dose. Water equivalence of various solid phantoms such as solid water, virtual water, RW1, PMMA, polystyrene, and plastic water materials are investigated at 137 Cs energy under full scatter conditions. The investigation reveals that solid water, virtual water, and RW1 phantoms are water equivalent up to 15 cm from the source. Phantom materials such as plastic water, PMMA, and polystyrene phantom materials are water equivalent up to 10 cm. At 15 cm from the source, the phantom scatter corrections are 1.035, 1.050, and 0.949 for the phantoms PMMA, plastic water, and polystyrene, respectively. (author)

  10. Contrast detail phantom for SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Cabrejas, M.L. de; Arashiro, J G; Giannone, C. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Camuyrano, M; Nohara, G [Universidad de Buenos Aires, Buenos Aires (Argentina). Facultad Ciencias Exactas

    1996-06-01

    A new low variable contrast phantom for single photon emission computed tomography (SPECT) was constructed, tested and compared with other existing phantoms. It contains simulated cylindrical lesions of four different diameters (D{sub i}), embedded in a cylindrical scattering medium and a uniform section to evaluate tomographic uniformity. The concentration of tracer in the simulated lesions and the scattering medium (background) can be varied to simulate hot and cold lesions. Different applications of the phantom were tested, including determination of the minimum object contrast (OCm) necessary to detect lesions as a function of lesion size, lesion type (hot or cold) and acquisition and processing protocols by visual inspection. This parameter allows categorization of instruments comparing an `image quality index` (IQI). Preliminary comparison with the Britten contrast processing method showed that the detectable OCm was of the same order of magnitude, but the presented device seems more suitable for training and intercomparison purposes. The constructed phantom, of simple design, has proved to be useful for acquisition and processing condition evaluation, OCm estimation and external quality control. (author). 11 refs, 4 figs.

  11. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

    NARCIS (Netherlands)

    Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang

    2011-01-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

  12. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; Heijblom, M.; Steenbergen, Wiendelt; van Leeuwen, Ton; Manohar, Srirang

    2011-01-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F–T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

  13. Development of breast phantom for quality assessment of mammographic images

    Energy Technology Data Exchange (ETDEWEB)

    Arvelos, Jeniffer Miranda; Flores, Mabel Bustos; Amaral, Fernando; Rio, Margarita Chevalier del; Mourao, Arnaldo Prata, E-mail: jenifferarvelos00@gmail.com [Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil). Centro de Engenharia Biomedica; Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Universidad Complutense de Madrid (UCM), Madrid (Spain). Faculdad de Medicina. Departmento de Radiologia

    2017-11-01

    Diagnosis of breast cancer in young women may be impaired by the tissue composition of breast in this age group, as fibroglandular tissue is present in greater amount in young women and it has higher density than fibrous and fatty tissues which predominate in women older than 40 years old. The higher density of breast tissue makes it difficult to identify nodules in two-dimensional techniques, due to the overlapping of dense layers. Breast phantoms are used in evaluation and quality control of clinical images, and therefore, it is important to develop non-homogeneous phantoms that may better simulate a real breast. Grouped microcalcifications are often the earliest changes associated with malignant neoplasm of breast. In this work, a phantom was developed in the form of a compressed breast using acrylic resin blend. The resin blend used to fulfill the interior of the phantom has similar mammographic density to the one in fibroglandular tissue, representing a dense breast. The lesions were made of acrylic resin blend and calcium compounds that might simulate breast abnormalities, representing nodules, macrocalcifications and microcalcifications of different dimensions and densities. They were distributed into the ma-terial representing fibroglandular tissue. The developed phantom has a thickness of 1 cm, and it may be matched with other plates to represent a dense breast of thickness between 5 and 6 cm. The main goal of the project is to evaluate the sensitivity of detection of these calcifications in relation to their density and location in the breast in two-dimensional images generated in mammography equipment. Mammographic images allow the visualization of the changes implemented in the phantom. The developed phantom may be used in evaluation of diagnostic images generated through two-dimensional and three-dimensional images. (author)

  14. Development of breast phantom for quality assessment of mammographic images

    International Nuclear Information System (INIS)

    Arvelos, Jeniffer Miranda; Flores, Mabel Bustos; Amaral, Fernando; Rio, Margarita Chevalier del; Mourao, Arnaldo Prata; Universidade Federal de Minas Gerais; Universidad Complutense de Madrid

    2017-01-01

    Diagnosis of breast cancer in young women may be impaired by the tissue composition of breast in this age group, as fibroglandular tissue is present in greater amount in young women and it has higher density than fibrous and fatty tissues which predominate in women older than 40 years old. The higher density of breast tissue makes it difficult to identify nodules in two-dimensional techniques, due to the overlapping of dense layers. Breast phantoms are used in evaluation and quality control of clinical images, and therefore, it is important to develop non-homogeneous phantoms that may better simulate a real breast. Grouped microcalcifications are often the earliest changes associated with malignant neoplasm of breast. In this work, a phantom was developed in the form of a compressed breast using acrylic resin blend. The resin blend used to fulfill the interior of the phantom has similar mammographic density to the one in fibroglandular tissue, representing a dense breast. The lesions were made of acrylic resin blend and calcium compounds that might simulate breast abnormalities, representing nodules, macrocalcifications and microcalcifications of different dimensions and densities. They were distributed into the ma-terial representing fibroglandular tissue. The developed phantom has a thickness of 1 cm, and it may be matched with other plates to represent a dense breast of thickness between 5 and 6 cm. The main goal of the project is to evaluate the sensitivity of detection of these calcifications in relation to their density and location in the breast in two-dimensional images generated in mammography equipment. Mammographic images allow the visualization of the changes implemented in the phantom. The developed phantom may be used in evaluation of diagnostic images generated through two-dimensional and three-dimensional images. (author)

  15. Monte Carlo dose calculations for phantoms with hip prostheses

    International Nuclear Information System (INIS)

    Bazalova, M; Verhaegen, F; Coolens, C; Childs, P; Cury, F; Beaulieu, L

    2008-01-01

    Computed tomography (CT) images of patients with hip prostheses are severely degraded by metal streaking artefacts. The low image quality makes organ contouring more difficult and can result in large dose calculation errors when Monte Carlo (MC) techniques are used. In this work, the extent of streaking artefacts produced by three common hip prosthesis materials (Ti-alloy, stainless steel, and Co-Cr-Mo alloy) was studied. The prostheses were tested in a hypothetical prostate treatment with five 18 MV photon beams. The dose distributions for unilateral and bilateral prosthesis phantoms were calculated with the EGSnrc/DOSXYZnrc MC code. This was done in three phantom geometries: in the exact geometry, in the original CT geometry, and in an artefact-corrected geometry. The artefact-corrected geometry was created using a modified filtered back-projection correction technique. It was found that unilateral prosthesis phantoms do not show large dose calculation errors, as long as the beams miss the artefact-affected volume. This is possible to achieve in the case of unilateral prosthesis phantoms (except for the Co-Cr-Mo prosthesis which gives a 3% error) but not in the case of bilateral prosthesis phantoms. The largest dose discrepancies were obtained for the bilateral Co-Cr-Mo hip prosthesis phantom, up to 11% in some voxels within the prostate. The artefact correction algorithm worked well for all phantoms and resulted in dose calculation errors below 2%. In conclusion, a MC treatment plan should include an artefact correction algorithm when treating patients with hip prostheses

  16. Introduction of a stack-phantom for PET

    International Nuclear Information System (INIS)

    Jonsson, C.; Schnell, P.O.; Jacobsson, H.; Engelin, L.; Danielsson, A.M.; Johansson, L.; Larsson, S.A.; Pagani, M.; Stone-Elander, S.

    2002-01-01

    Aim: We have previously developed a new flexible phantom system for SPECT, i.e. 'the stack phantom' (Eur. J. Nucl. Med. 27, No.2, 131-139, 2000). The unique feature of this phantom system is that it allows studies with, as well as without major degrading impacts from photon attenuation and Compton scattering. The specific aim of this work was to further develop the system with special reference to PET. Material and methods: The principle of the phantom concept is discrete sampling of 3D objects by a series of equidistant 2D planes. The 2D planes are a digitised set of 2D sections, representing the radioactivity distribution in the object of interest. Using a grey scale related to the radioactivity concentration, selected images are printed by radioactive ink on thin paper sheets and stacked into the 3D structure with low-density or with tissue equivalent material in between. Using positron emitting radionuclides, the paper sheets alone may not be sufficiently thick to avoid annihilation losses due to escaping positrons. In order to investigate the amount of additional material needed, a spot of radioactivity ( 18 F) was printed out and subsequently covered by adding thin plastic films (0.055mm) on both sides of the paper. Short PET scans (ECAT 921) were performed and the count-rate was registered after each additional layer of plastic cover. A first prototype, a cylindrical cold-spot phantom was constructed on the basis of these results. Nine identical sheets were printed out and first mounted in between 4 mm plates of polystyrene (density 1.04 g/cm 3 ). After a PET-scan, the paper sheets were re-mounted in between a low-density material (Divinycell, H30, density 0.03 g/cm 3 ) before repeating the PET scan. Results: For 18 F, the number of registered annihilation photons increased with increasing number of plastic sheets from 70% for the pure paper sheet to about 100% with 0.5 mm plastic cover on each side. PET of the low-density stacked cold spot phantom

  17. A comparative study on patient specific absolute dosimetry using slab phantom, acrylic body phantom and goat head phantom

    Directory of Open Access Journals (Sweden)

    Om Prakash Gurjar

    2015-01-01

    Full Text Available Purpose: To compare the results of patient specific absolute dosimetry using slab phantom, acrylic body phantom and goat head phantom. Methods: Fifteen intensity modulated radiotherapy (IMRT plans already planned on treatment planning system (TPS for head-and-neck cancer patients were exported on all three kinds of phantoms viz. slab phantom, acrylic body phantom and goat head phantom, and dose was calculated using anisotropic analytic algorithm (AAA. All the gantry angles were set to zero in case of slab phantom while set to as it is in actual plan in case of other two phantoms. All the plans were delivered by linear accelerator (LA and dose for each plan was measured by 0.13 cc ion chamber. The percentage (% variations between planned and measured doses were calculated and analyzed. Results: The mean % variations between planned and measured doses of all IMRT quality assurance (QA plans were as 0.65 (Standard deviation (SD: 0.38 with confidence limit (CL 1.39, 1.16 (SD: 0.61 with CL 2.36 and 2.40 (SD: 0.86 with CL 4.09 for slab phantom, acrylic head phantom and goat head phantom respectively. Conclusion: Higher dose variations found in case of real tissue phantom compare to results in case of slab and acrylic body phantoms. The algorithm AAA does not calculate doses in heterogeneous medium as accurate as it calculates in homogeneous medium. Therefore the patient specific absolute dosimetry should be done using heterogeneous phantom mimicking density wise as well as design wise to the actual human body.  

  18. The design and fabrication of two portal vein flow phantoms by different methods

    Energy Technology Data Exchange (ETDEWEB)

    Yunker, Bryan E., E-mail: bryan.yunker@ucdenver.edu; Lanning, Craig J.; Shandas, Robin; Hunter, Kendall S. [Department of Bioengineering, University of Colorado – Denver/Anschutz, 12700 East 19th Avenue, MS 8607, Aurora, Colorado 80045 (United States); Dodd, Gerald D., E-mail: gerald.dodd@ucdenver.edu; Chang, Samuel; Scherzinger, Ann L. [Department of Radiology, University of Colorado – SOM, 12401 East 17th Avenue, Mail Stop L954, Aurora, Colorado 80045 (United States); Chen, S. James, E-mail: james.chen@ucdenver.edu [Department of Medicine, University of Colorado Denver, Colorado 80045 and Department of Medicine/Cardiology, University of Colorado – SOM, 12401 East 17th Avenue, Mail Stop B132, Aurora, Colorado 80045 (United States); Feng, Yusheng, E-mail: yusheng.feng@utsa.edu [Department of Mechanical Engineering, University of Texas – San Antonio, One UTSA Circle, Mail Stop: AET 2.332, San Antonio, Texas 78249–0670 (United States)

    2014-02-15

    Purpose: This study outlines the design and fabrication techniques for two portal vein flow phantoms. Methods: A materials study was performed as a precursor to this phantom fabrication effort and the desired material properties are restated for continuity. A three-dimensional portal vein pattern was created from the Visual Human database. The portal vein pattern was used to fabricate two flow phantoms by different methods with identical interior surface geometry using computer aided design software tools and rapid prototyping techniques. One portal flow phantom was fabricated within a solid block of clear silicone for use on a table with Ultrasound or within medical imaging systems such as MRI, CT, PET, or SPECT. The other portal flow phantom was fabricated as a thin walled tubular latex structure for use in water tanks with Ultrasound imaging. Both phantoms were evaluated for usability and durability. Results: Both phantoms were fabricated successfully and passed durability criteria for flow testing in the next project phase. Conclusions: The fabrication methods and materials employed for the study yielded durable portal vein phantoms.

  19. NMR-CT image and symbol phantoms

    International Nuclear Information System (INIS)

    Hongo, Syozo; Yamaguchi, Hiroshi; Takeshita, Hiroshi

    1990-01-01

    We have developed Japanese phantoms in two procedures. One is described as a mathematical expression. Another is 'symbol phantoms' in 3 dimensional picture-elements, each of which symbolize an organ name. The concept and the algorithm of the symbol phantom enables us to make a phantom for a individual in terms of all his transversal section images. We got 85 transversal section images of head and trunk parts, and those of 40 legs parts by using NMR-CT. We have made the individual phantom for computation of organ doses. The transversal section images were not so clear to identify all organs needed to dose estimation that we had to do hand-editing the shapes of organs with viewing a typical section images: we could not yet make symbol phantom in a automatic editing. Symbols were coded to be visual cords as ASCII characters. After we got the symbol phantom of the first stage, we can edit it easily using a word-processor. Symbol phantom could describe more freely the shape of organs than mathematical phantom. Symbol phantom has several advantages to be an individual phantom, but the only difficult point is how to determine its end-point as a reference man when we apply the method to build the reference man. (author)

  20. Design and evaluation of corn starch-bonded Rhizophora spp. particleboard phantoms for SPECT/CT imaging

    Science.gov (United States)

    Hamid, Puteri Nor Khatijah Abd; Yusof, Mohd Fahmi Mohd; Aziz Tajuddin, Abd; Hashim, Rokiah; Zainon, Rafidah

    2018-01-01

    The aim of this study was to design and evaluate of corn starch-bonded Rhizophora spp. particleboards as phantom for SPECT/CT imaging. The phantom was designed according to the Jaszczak phantom commonly used in SPECT imaging with dimension of 22 cm diameter and 18 cm length. Six inserts with different diameter were made for insertion of vials filled with 1.6 µCi/ml of 99mTc unsealed source. The particleboard phantom was scanned using SPECT/CT imaging protocol. The contrast of each vial for particleboards phantom were calculated based on the ratio of counts in radionuclide volume and phantom background and compared to Perspex® and water phantom. The results showed that contrast values for each vial in particleboard phantomis near to 1.0 and in good agreement with Perspex® and water phantoms as common phantom materials for SPECT/CT. The paired sample t-test result showed no significant difference of contrast values between images in particleboard phantoms and that in water. The overall results showed the potential of corn starch-bonded Rhizophora spp. as phantom for quality control and dosimetry works in SPECT/CT imaging.

  1. Estimation of computed tomography dose in various phantom shapes and compositions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Lae [Dept. of Radiological Science, Yonsei University, Seoul (Korea, Republic of)

    2017-03-15

    The purpose of this study was to investigate CTDI (computed tomography dose index at center) for various phantom shapes, sizes, and compositions by using GATE (geant4 application for tomographic emission) simulations. GATE simulations were performed for various phantom shapes (cylinder, elliptical, and hexagonal prism PMMA phantoms) and phantom compositions (water, PMMA, polyethylene, polyoxymethylene) with various diameters (1-50 cm) at various kVp and mAs levels. The CTDI100center values of cylinder, elliptical, and hexagonal prism phantom at 120 kVp, 200 mAs resulted in 11.1, 13.4, and 12.2 mGy, respectively. The volume is the same, but CTDI{sub 100center} values are different depending on the type of phantom. The water, PMMA, and polyoxymethylene phantom CTDI{sub 100center} values were relatively low as the material density increased. However, in the case of Polyethylene, the CTDI{sub 100center} value was higher than that of PMMA at diameters exceeding 15 cm (CTDI{sub 100center} : 35.0 mGy). And a diameter greater than 30 cm (CTDI{sub 100center} : 17.7 mGy) showed more CTDI{sub 100center} than Water. We have used limited phantoms to evaluate CT doses. In this study, CTDI{sub 100center} values were estimated and simulated by GATE simulation according to the material and shape of the phantom. CT dosimetry can be estimated more accurately by using various materials and phantom shapes close to human body.

  2. Conversion of ICRP male reference phantom to polygon-surface phantom

    Science.gov (United States)

    Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

    2013-10-01

    The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (original ICRP reference phantoms, it is believed that the polygon-surface version of ICRP reference phantoms properly developed will not only provide the same or similar dose values (say, difference <5 or 10%) for highly penetrating radiations, but also provide correct dose values for the weakly penetrating

  3. Effect of phantom voxelization in CT simulations

    International Nuclear Information System (INIS)

    Goertzen, Andrew L.; Beekman, Freek J.; Cherry, Simon R.

    2002-01-01

    In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors are introduced due to the phantom voxelization. To study effects of phantom discretization, analytical CT simulations were run for a fan-beam geometry with phantom voxel sizes ranging from 0.0625 to 2 times the reconstructed pixel size and noise levels corresponding to 10 3 -10 7 photons per detector pixel prior to attenuation. The number of rays traced per detector element was varied from 1 to 16. Differences in the filtered backprojection images caused by changing the phantom matrix sizes and number of rays traced were assessed by calculating the difference between reconstructions based on the finest matrix and coarser matrix simulations. In noise free simulations, all phantom matrix sizes produced a measurable difference in comparison with the finest phantom matrix used. When even a small amount of noise was added to the projection data, the differences due to the phantom discretization were masked by the noise, and in all cases there was almost no improvement by using a phantom matrix that was more than twice as fine as the reconstruction matrix. No substantial improvement was achieved by tracing more than 4 rays per detector pixel

  4. Spherical phantom for research of radiation situation in outer space. Design-structural special features

    International Nuclear Information System (INIS)

    Kartsev, I.S.; Eremenko, V.G.; Petrov, V.I.; Polenov, B.V.; Yudin, V.N.; Akatov, Yu.A.; Petrov, V.M.; Shurshakov, V.A.

    2005-01-01

    The design-structural features of the updated spherical phantom applied within the frameworks of the space experiment Matreshka-R at the Russian segment of International space station during ISS-8 and ISS-9 expeditions are described. The replacement of 48 polyethylene containers with TLD and STD assemblies by 16 cases installed from external side of the phantom and 4 tissue-equivalent caps of the central disk by 4 cases with detector assemblies is carried out. The updated tissue-equivalent phantom contains the active dosemeter based on 5 MOS detectors. The phantom cover is made from the non-flammable material NT-7. The basic characteristics of the flight specimen of the phantom are presented. The results of its on-Earth testing and real space flights are analyzed [ru

  5. A Software Phantom : Application in Digital Tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Lazos, D; Kolitsi, Z; Badea, C; Pallikarakis, N [Medical Physics Laboratory, School of Medicine, Univercity of Patras (Greece)

    1999-12-31

    A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author) 4 refs., 3 figs

  6. A Software Phantom : Application in Digital Tomosynthesis

    International Nuclear Information System (INIS)

    Lazos, D.; Kolitsi, Z.; Badea, C.; Pallikarakis, N.

    1998-01-01

    A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author)

  7. MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

    International Nuclear Information System (INIS)

    Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D

    2015-01-01

    Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647

  8. MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

    Energy Technology Data Exchange (ETDEWEB)

    Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647.

  9. SU-C-209-07: Phantoms for Digital Breast Tomosynthesis Imaging System Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D; Liu, Y [Medical College of Wisconsin, Milwaukee, WI (United States)

    2016-06-15

    Purpose: Digital Breast Tomosynthesis (DBT) is gaining importance in breast imaging. There is a need for phantoms that can be used for image evaluation and comparison. Existing commercially available phantoms for DBT are expensive and may lack clinically relevant test objects. The purpose of this study is to develop phantoms for DBT evaluation. Methods Four phantoms have been designed and constructed to assess the image quality (IQ) of two DBT systems. The first contains a spiral of 0.3 mm SiC beads in gelatin to measure the tomographic slice thickness profile and uniformity of coverage in a series of tomographic planes. The second contains simulated tumors inclined with respect to the phantom base to assess tomographic image quality. The third has a tilted array of discs with varying contrast and diameter. This phantom was imaged alone and in a stack of TE slabs giving 2 to 10 cm thickness. The fourth has a dual wedge of glandular and adipose simulating materials. One wedge contains discs with varying diameter and thickness; the other supports a mass with six simulated spicules of varying size and a cluster of simulated calcifications. The simulated glandular tissue material varies between 35 and 100% of the total thickness (5.5 cm). Results: All phantoms were scanned successfully. The best IQ comparison was achieved with the dual wedge phantom as demonstrated by the spiculated mass and calcifications. Images were evaluated by two radiologists and one physicist. The projection images and corresponding set of tomographic planes were comparable and the synthesized projection images were inferior to the projection images for both systems. Conclusion: Four phantoms were designed, constructed and imaged on two DBT systems. They successfully demonstrated performance differences between two systems, and between true and synthesized projection images. Future work will incorporate these designs into a single phantom.

  10. Characterisation of an anthropomorphic chest phantom for dose measurements in radiology beams

    Science.gov (United States)

    Henriques, L. M. S.; Cerqueira, R. A. D.; Santos, W. S.; Pereira, A. J. S.; Rodrigues, T. M. A.; Carvalho Júnior, A. B.; Maia, A. F.

    2014-02-01

    The objective of this study was to characterise an anthropomorphic chest phantom for dosimetric measurements of conventional radiology beams. This phantom was developed by a previous research project at the Federal University of Sergipe for image quality control tests. As the phantom consists of tissue-equivalent material, it is possible to characterise it for dosimetric studies. For comparison, a geometric chest phantom, consisting of PMMA (polymethylmethacrylate) with dimensions of 30×30×15 cm³ was used. Measurements of incident air kerma (Ki) and entrance surface dose (ESD) were performed using ionisation chambers. From the results, backscatter factors (BSFs) of the two phantoms were determined and compared with values estimated by CALDose_X software, based on a Monte Carlo simulation. For the technical parameters evaluated in this study, the ESD and BSF values obtained experimentally showed a good similarity between the two phantoms, with minimum and maximum difference of 0.2% and 7.0%, respectively, and showed good agreement with the results published in the literature. Organ doses and effective doses for the anthropomorphic phantom were also estimated by the determination of conversion coefficients (CCs) using the visual Monte Carlo (VMC) code. Therefore, the results of this study prove that the anthropomorphic thorax phantom proposed is a good tool to use in dosimetry and can be used for risk evaluation of X-ray diagnostic procedures.

  11. Evaluation of tomosynthesis elastography in a breast-mimicking phantom

    International Nuclear Information System (INIS)

    Engelken, Florian Jan; Sack, Ingolf; Klatt, Dieter; Fischer, Thomas; Fallenberg, Eva Maria; Bick, Ulrich; Diekmann, Felix

    2012-01-01

    Objective: To evaluate whether measurement of strain under static compression in tomosynthesis of a breast-mimicking phantom can be used to distinguish tumor-simulating lesions of different elasticities and to compare the results to values predicted by rheometric analysis as well as results of ultrasound elastography. Materials and methods: We prepared three soft breast-mimicking phantoms containing simulated tumors of different elasticities. The phantoms were imaged using a wide angle tomosynthesis system with increasing compression settings ranging from 0 N to 105 N in steps of 15 N. Strain of the inclusions was measured in two planes using a commercially available mammography workstation. The elasticity of the phantom matrix and inclusion material was determined by rheometric analysis. Ultrasound elastography of the inclusions was performed using two different ultrasound elastography algorithms. Results: Strain at maximal compression was 24.4%/24.5% in plane 1/plane 2, respectively, for the soft inclusion, 19.6%/16.9% for the intermediate inclusion, and 6.0%/10.2% for the firm inclusion. The strain ratios predicted by rheometrical testing were 0.41, 0.83 and 1.26 for the soft, intermediate, and firm inclusions, respectively. The strain ratios obtained for the soft, intermediate, and firm inclusions were 0.72 ± 0.13, 1.02 ± 0.21 and 2.67 ± 1.70, respectively for tomosynthesis elastography, 0.91, 1.64 and 2.07, respectively, for ultrasound tissue strain imaging, and 0.97, 2.06 and 2.37, respectively, for ultrasound real-time elastography. Conclusions: Differentiation of tumor-simulating inclusions by elasticity in a breast mimicking phantom may be possible by measuring strain in tomosynthesis. This method may be useful for assessing elasticity of breast lesions tomosynthesis of the breast

  12. Do you believe in phantoms?

    CERN Multimedia

    Rosaria Marraffino

    2015-01-01

    “Phantoms” are tools that simulate a therapy’s response by mimicking the conditions of the human body. They are required in hadron therapy in order to optimise and verify the therapy before performing it on the patient. The better the phantom, the more accurate the treatment plan and the more effective the therapy. In the framework of the EU-funded project ENTERVISION*, a team of CERN researchers has designed an innovative piece of equipment able to evaluate radiobiology-related parameters in a very accurate way.   The ENTERVISION phantom being tested at HIT. A key challenge in hadron therapy – i.e. the medical use of hadrons to treat cancer – is to evaluate the biological effect of the delivered radiation. This can be achieved by using accurate dosimetry techniques to study the biological response in terms of the dose deposited and other physical parameters of the beam, such as the Linear Energy Transfer (LET). The job of the “phan...

  13. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited.

    Science.gov (United States)

    Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

    2011-07-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

  14. An investigation of the effects from a urethral warming system on temperature distributions during cryoablation treatment of the prostate: a phantom study.

    Science.gov (United States)

    Favazza, C P; Gorny, K R; King, D M; Rossman, P J; Felmlee, J P; Woodrum, D A; Mynderse, L A

    2014-08-01

    Introduction of urethral warmers to aid cryosurgery in the prostate has significantly reduced the incidence of urethral sloughing; however, the incidence rate still remains as high as 15%. Furthermore, urethral warmers have been associated with an increase of cancer recurrence rates. Here, we report results from our phantom-based investigation to determine the impact of a urethral warmer on temperature distributions around cryoneedles during cryosurgery. Cryoablation treatments were simulated in a tissue mimicking phantom containing a urethral warming catheter. Four different configurations of cryoneedles relative to urethral warming catheter were investigated. For each configuration, the freeze-thaw cycles were repeated with and without the urethral warming system activated. Temperature histories were recorded at various pre-arranged positions relative to the cryoneedles and urethral warming catheter. In all configurations, the urethral warming system was effective at maintaining sub-lethal temperatures at the simulated surface of the urethra. The warmer action, however, was additionally demonstrated to potentially negatively impact treatment lethality in the target zone by elevating minimal temperatures to sub-lethal levels. In all needle configurations, rates of freezing and thawing were not significantly affected by the use of the urethral warmer. The results indicate that the urethral warming system can protect urethral tissue during cryoablation therapy with cryoneedles placed as close as 5mm to the surface of the urethra. Using a urethral warming system and placing multiple cryoneedles within 1cm of each other delivers lethal cooling at least 5mm from the urethral surface while sparing urethral tissue. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Radiographic test phantom for computed tomographic lung nodule analysis

    International Nuclear Information System (INIS)

    Zerhouni, E.A.

    1987-01-01

    This patent describes a method for evaluating a computed tomograph scan of a nodule in a lung of a human or non-human animal. The method comprises generating a computer tomograph of a transverse section of the animal containing lung and nodule tissue, and generating a second computer tomograph of a test phantom comprising a device which simulates the transverse section of the animal. The tissue simulating portions of the device are constructed of materials having radiographic densities substantially identical to those of the corresponding tissue in the simulated transverse section of the animal and have voids therein which simulate, in size and shape, the lung cavities in the transverse section and which contain a test reference nodule constructed of a material of predetermined radiographic density which simulates in size, shape and position within a lung cavity void of the test phantom the nodule in the transverse section of the animal and comparing the respective tomographs

  16. Three-dimensional printer-generated patient-specific phantom for artificial in vivo dosimetry in radiotherapy quality assurance.

    Science.gov (United States)

    Kamomae, Takeshi; Shimizu, Hidetoshi; Nakaya, Takayoshi; Okudaira, Kuniyasu; Aoyama, Takahiro; Oguchi, Hiroshi; Komori, Masataka; Kawamura, Mariko; Ohtakara, Kazuhiro; Monzen, Hajime; Itoh, Yoshiyuki; Naganawa, Shinji

    2017-12-01

    Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material. Radiophotoluminescence glass dosimeters can be inserted in the 3D-printed phantom. The phantom shape, CT value, and absorbed doses are compared between the actual and 3D-printed phantoms. The shape difference between the actual and printed phantoms is less than 1 mm except in the bottom surface region. The average CT value of the infill region in the 3D-printed phantom is -6 ± 18 Hounsfield units (HU) and that of the vertical shell region is 126 ± 18 HU. When the same plans were irradiated, the dose differences were generally less than 2%. These results demonstrate the feasibility of the 3D-printed phantom for artificial in vivo dosimetry in radiotherapy quality assurance. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Phantom pain and phantom sensations in upper limb amputees : an epidemiological study

    NARCIS (Netherlands)

    Kooijman, CM; Dijkstra, PU; Geertzen, JHB; Elzinga, A; van der Schans, CP

    Phantom pain in subjects with an amputated limb is a well-known problem. However, estimates of the prevalence of phantom pain differ considerably in the literature. Various factors associated with phantom pain have been described including pain before the amputation, gender, dominance, and time

  18. Advanced Radiation DOSimetry phantom (ARDOS): a versatile breathing phantom for 4D radiation therapy and medical imaging

    Science.gov (United States)

    Kostiukhina, Natalia; Georg, Dietmar; Rollet, Sofia; Kuess, Peter; Sipaj, Andrej; Andrzejewski, Piotr; Furtado, Hugo; Rausch, Ivo; Lechner, Wolfgang; Steiner, Elisabeth; Kertész, Hunor; Knäusl, Barbara

    2017-10-01

    A novel breathing phantom was designed for being used in conventional and ion-beam radiotherapy as well as for medical imaging. Accurate dose delivery and patient safety are aimed to be verified for four-dimensional (4D) treatment techniques compensating for breathing-induced tumor motion. The phantom includes anthropomorphic components representing an average human thorax. It consists of real tissue equivalent materials to fulfill the requirements for dosimetric experiments and imaging purposes. The different parts of the torso (lungs, chest wall, and ribs) and the tumor can move independently. Simple regular movements, as well as more advanced patient-specific breathing cycles are feasible while a reproducible setup can be guaranteed. The phantom provides the flexibility to use different types of dosimetric devices and was designed in a way that it is robust, transportable and easy to handle. Tolerance levels and the reliability of the phantom setup were determined in combination with tests on motion accuracy and reproducibility by using infrared optical tracking technology. Different imaging was performed including positron emission tomography imaging, 4D computed tomography as well as real-time in-room imaging. The initial dosimetric benchmarking studies were performed in a photon beam where dose parameters are predictable and the dosimetric procedures well established.

  19. Advanced Radiation DOSimetry phantom (ARDOS): a versatile breathing phantom for 4D radiation therapy and medical imaging.

    Science.gov (United States)

    Kostiukhina, Natalia; Georg, Dietmar; Rollet, Sofia; Kuess, Peter; Sipaj, Andrej; Andrzejewski, Piotr; Furtado, Hugo; Rausch, Ivo; Lechner, Wolfgang; Steiner, Elisabeth; Kertész, Hunor; Knäusl, Barbara

    2017-10-04

    A novel breathing phantom was designed for being used in conventional and ion-beam radiotherapy as well as for medical imaging. Accurate dose delivery and patient safety are aimed to be verified for four-dimensional (4D) treatment techniques compensating for breathing-induced tumor motion. The phantom includes anthropomorphic components representing an average human thorax. It consists of real tissue equivalent materials to fulfill the requirements for dosimetric experiments and imaging purposes. The different parts of the torso (lungs, chest wall, and ribs) and the tumor can move independently. Simple regular movements, as well as more advanced patient-specific breathing cycles are feasible while a reproducible setup can be guaranteed. The phantom provides the flexibility to use different types of dosimetric devices and was designed in a way that it is robust, transportable and easy to handle. Tolerance levels and the reliability of the phantom setup were determined in combination with tests on motion accuracy and reproducibility by using infrared optical tracking technology. Different imaging was performed including positron emission tomography imaging, 4D computed tomography as well as real-time in-room imaging. The initial dosimetric benchmarking studies were performed in a photon beam where dose parameters are predictable and the dosimetric procedures well established.

  20. Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

    Science.gov (United States)

    Albanese, Kathryn Elizabeth

    Scatter in medical imaging is typically cast off as image-related noise that detracts from meaningful diagnosis. It is therefore typically rejected or removed from medical images. However, it has been found that every material, including cancerous tissue, has a unique X-ray coherent scatter signature that can be used to identify the material or tissue. Such scatter-based tissue-identification provides the advantage of locating and identifying particular materials over conventional anatomical imaging through X-ray radiography. A coded aperture X-ray coherent scatter spectral imaging system has been developed in our group to classify different tissue types based on their unique scatter signatures. Previous experiments using our prototype have demonstrated that the depth-resolved coherent scatter spectral imaging system (CACSSI) can discriminate healthy and cancerous tissue present in the path of a non-destructive x-ray beam. A key to the successful optimization of CACSSI as a clinical imaging method is to obtain anatomically accurate phantoms of the human body. This thesis describes the development and fabrication of 3D printed anatomical scatter phantoms of the breast and lung. The purpose of this work is to accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Tissue-equivalent anatomical phantoms were designed to assess the capability of the CACSSI system to classify different types of breast tissue (adipose, fibroglandular, malignant). These phantoms were 3D printed based on DICOM data obtained from CT scans of prone breasts. The phantoms were tested through comparison of measured scatter signatures with those of adipose and fibroglandular tissue from literature. Tumors in the phantom were modeled using a variety of biological tissue including actual surgically excised benign and malignant tissue specimens. Lung based phantoms have also been printed for future

  1. Low cost phantom for computed radiology; Objeto de teste de baixo custo para radiologia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Travassos, Paulo Cesar B.; Magalhaes, Luis Alexandre G., E-mail: pctravassos@ufrj.br [Universidade do Estado do Rio de Janeiro (IBRGA/UERJ), RJ (Brazil). Laboratorio de Ciencias Radiologicas; Augusto, Fernando M.; Sant' Yves, Thalis L.A.; Goncalves, Elicardo A.S. [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil); Botelho, Marina A. [Hospital Universitario Pedro Ernesto (UERJ), Rio de Janeiro, RJ (Brazil)

    2012-08-15

    This article presents the results obtained from a low cost phantom, used to analyze Computed Radiology (CR) equipment. The phantom was constructed to test a few parameters related to image quality, as described in [1-9]. Materials which can be easily purchased were used in the construction of the phantom, with total cost of approximately U$100.00. A bar pattern was placed only to verify the efficacy of the grids in the spatial resolution determination, and was not included in the budget because the data was acquired from the grids. (author)

  2. A deformable head and neck phantom with in-vivo dosimetry for adaptive radiotherapy quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Graves, Yan Jiang [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Physics, University of California San Diego, La Jolla, California 92093 (United States); Smith, Arthur-Allen; Mcilvena, David; Manilay, Zherrina; Lai, Yuet Kong [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States); Rice, Roger; Mell, Loren; Cerviño, Laura, E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 (United States); Jia, Xun; Jiang, Steve B., E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75235 (United States)

    2015-04-15

    Purpose: Patients’ interfractional anatomic changes can compromise the initial treatment plan quality. To overcome this issue, adaptive radiotherapy (ART) has been introduced. Deformable image registration (DIR) is an important tool for ART and several deformable phantoms have been built to evaluate the algorithms’ accuracy. However, there is a lack of deformable phantoms that can also provide dosimetric information to verify the accuracy of the whole ART process. The goal of this work is to design and construct a deformable head and neck (HN) ART quality assurance (QA) phantom with in vivo dosimetry. Methods: An axial slice of a HN patient is taken as a model for the phantom construction. Six anatomic materials are considered, with HU numbers similar to a real patient. A filled balloon inside the phantom tissue is inserted to simulate tumor. Deflation of the balloon simulates tumor shrinkage. Nonradiopaque surface markers, which do not influence DIR algorithms, provide the deformation ground truth. Fixed and movable holders are built in the phantom to hold a diode for dosimetric measurements. Results: The measured deformations at the surface marker positions can be compared with deformations calculated by a DIR algorithm to evaluate its accuracy. In this study, the authors selected a Demons algorithm as a DIR algorithm example for demonstration purposes. The average error magnitude is 2.1 mm. The point dose measurements from the in vivo diode dosimeters show a good agreement with the calculated doses from the treatment planning system with a maximum difference of 3.1% of prescription dose, when the treatment plans are delivered to the phantom with original or deformed geometry. Conclusions: In this study, the authors have presented the functionality of this deformable HN phantom for testing the accuracy of DIR algorithms and verifying the ART dosimetric accuracy. The authors’ experiments demonstrate the feasibility of this phantom serving as an end

  3. Characterization and validation of the thorax phantom Lungman for dose assessment in chest radiography optimization studies.

    Science.gov (United States)

    Rodríguez Pérez, Sunay; Marshall, Nicholas William; Struelens, Lara; Bosmans, Hilde

    2018-01-01

    This work concerns the validation of the Kyoto-Kagaku thorax anthropomorphic phantom Lungman for use in chest radiography optimization. The equivalence in terms of polymethyl methacrylate (PMMA) was established for the lung and mediastinum regions of the phantom. Patient chest examination data acquired under automatic exposure control were collated over a 2-year period for a standard x-ray room. Parameters surveyed included exposure index, air kerma area product, and exposure time, which were compared with Lungman values. Finally, a voxel model was developed by segmenting computed tomography images of the phantom and implemented in PENELOPE/penEasy Monte Carlo code to compare phantom tissue-equivalent materials with materials from ICRP Publication 89 in terms of organ dose. PMMA equivalence varied depending on tube voltage, from 9.5 to 10.0 cm and from 13.5 to 13.7 cm, for the lungs and mediastinum regions, respectively. For the survey, close agreement was found between the phantom and the patients' median values (deviations lay between 8% and 14%). Differences in lung doses, an important organ for optimization in chest radiography, were below 13% when comparing the use of phantom tissue-equivalent materials versus ICRP materials. The study confirms the value of the Lungman for chest optimization studies.

  4. SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

    International Nuclear Information System (INIS)

    Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D

    2016-01-01

    Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

  5. SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

    Energy Technology Data Exchange (ETDEWEB)

    Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

  6. The Japanese adult, child and infant phantoms

    International Nuclear Information System (INIS)

    Cristy, Mark; Egbert, Stephen D.

    1987-01-01

    The mathematical phantom for adult Japanese atomic-bomb survivors is a modification of the 57-kg ORNL (Oak Ridge National Laboratory) phantom for Western 15-year-old males and adult females. For younger Japanese survivors mathematical phantoms were similarly modified from the 18 and 9 kg ORNL phantoms for Western 5- and 1-year-olds, respectively. To make the phantom correspond more closely with dimensions and organ sizes recommended for Japanese adults by Maruyama and coworkers (cf E184), changes were made in the size of the lungs, the pancreas, the thyroid, and the testes and in the length of the legs. Also, the head-and-neck region was modified to improve the dose estimates for the thyroid from external radiation, after the ideas of Nagarajan et al. The arms were separated from the trunk to represent more accurately the shielding by the phantom in external exposures. Furthermore, provisions were made to provide a phantom in a kneeling posture. The elemental composition of the tissues was changed to that given by Kerr. The resulting phantom is slightly smaller in mass (55 kg). Details of these changes are given

  7. Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy.

    Directory of Open Access Journals (Sweden)

    Min-Joo Kim

    Full Text Available Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP and Polyjet has been purposed to utilize in patient-specific quality assurance (QA of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient's age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed

  8. Characterization of 3D printing techniques: Toward patient specific quality assurance spine-shaped phantom for stereotactic body radiation therapy.

    Science.gov (United States)

    Kim, Min-Joo; Lee, Seu-Ran; Lee, Min-Young; Sohn, Jason W; Yun, Hyong Geon; Choi, Joon Yong; Jeon, Sang Won; Suh, Tae Suk

    2017-01-01

    Development and comparison of spine-shaped phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet has been purposed to utilize in patient-specific quality assurance (QA) of stereotactic body radiation treatment. The developed 3D-printed spine QA phantom consisted of an acrylic body phantom and a 3D-printed spine shaped object. DLP and Polyjet 3D printers using a high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield units (HUs) were measured based on each CT image. Two different intensity-modulated radiotherapy plans based on both CT phantom image sets from the two printed spine-shaped phantoms with acrylic body phantoms were designed to deliver 16 Gy dose to the planning target volume (PTV) and were compared for target coverage and normal organ-sparing. Image fusion demonstrated good reproducibility of the developed phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than that for the Polyjet-generated phantom. The organs at risk received a lower dose for the 3D printed spine-shaped phantom image using the DLP technique than for the phantom image using the Polyjet technique. Despite using the same material for printing the spine-shaped phantom, these phantoms generated by different 3D printing techniques, DLP and Polyjet, showed different HU values and these differently appearing HU values according to the printing technique could be an extra consideration for developing the 3D printed spine-shaped phantom depending on the patient's age and the density of the spinal bone. Therefore, the 3D printing technique and materials should be carefully chosen by taking into account the condition of the patient in order to accurately produce 3D printed patient-specific QA

  9. A phantom for quality control in mammography

    International Nuclear Information System (INIS)

    Gambaccini, M.; Rimondi, O.; Marziani, M.; Toti, A.

    1989-01-01

    A phantom for evaluating image quality in mammography has been designed and will be used in the Italian national programme ''Dose and Quality in Mammography''. The characteristics of the phantom are (a) about the same X-ray transmission as a 5 cm 50% fat and 50% water breast for energies between 15 and 50 keV and (b) optimum energies for imaging of the test objects (included in the phantom) in very close agreement with the optimum energies for imaging of calcifications and tumours in a 5 cm 50% fat and 50% water breast. An experimental comparison between the prototype and some commercial phantoms was carried out. Measurements are in progress to test the phantom's ability to evaluate the performances of mammographic systems quantitatively. (author)

  10. SU-E-T-124: Anthropomorphic Phantoms for Confirmation of Linear Accelerator Based Small Animal Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Perks, J; Benedict, S [UC Davis Cancer Center, Sacramento, CA (United States); Lucero, S [UC Davis, Davis, CA (United States)

    2015-06-15

    Purpose: To document the support of radiobiological small animal research by a modern radiation oncology facility. This study confirms that a standard, human use linear accelerator can cover the range of experiments called for by researchers performing animal irradiation. A number of representative, anthropomorphic murine phantoms were made. The phantoms confirmed the small field photon and electron beams dosimetry validated the use of the linear accelerator for rodents. Methods: Laser scanning a model, CAD design and 3D printing produced the phantoms. The phantoms were weighed and CT scanned to judge their compatibility to real animals. Phantoms were produced to specifically mimic lung, gut, brain, and othotopic lesion irradiations. Each phantom was irradiated with the same protocol as prescribed to the live animals. Delivered dose was measured with small field ion chambers, MOS/FETs or TLDs. Results: The density of the phantom material compared to density range across the real mice showed that the printed material would yield sufficiently accurate measurements when irradiated. The whole body, lung and gut irradiations were measured within 2% of prescribed doses with A1SL ion chamber. MOSFET measurements of electron irradiations for the orthotopic lesions allowed refinement of the measured small field output factor to better than 2% and validated the immunology experiment of irradiating one lesion and sparing another. Conclusion: Linacs are still useful tools in small animal bio-radiation research. This work demonstrated a strong role for the clinical accelerator in small animal research, facilitating standard whole body dosing as well as conformal treatments down to 1cm field. The accuracy of measured dose, was always within 5%. The electron irradiations of the phantom brain and flank tumors needed adjustment; the anthropomorphic phantoms allowed refinement of the initial output factor measurements for these fields which were made in a large block of solid water.

  11. FABRICATION OF TISSUE-SIMULATIVE PHANTOMS AND CAPILLARIES AND THEIR INVESTIGATION BY OPTICAL COHERENCE TOMOGRAPHY TECHNIQUES

    Directory of Open Access Journals (Sweden)

    A. V. Bykov

    2013-03-01

    Full Text Available Methods of tissue-simulative phantoms and capillaries fabrication from PVC-plastisol and silicone for application as test-objects in optical coherence tomography (OCT and skin and capillary emulation are considered. Comparison characteristics of these materials and recommendations for their application are given. Examples of phantoms visualization by optical coherence tomography method are given. Possibility of information using from B-scans for refractive index evaluation is shown.

  12. A statistically defined anthropomorphic software breast phantom

    International Nuclear Information System (INIS)

    Lau, Beverly A.; Reiser, Ingrid; Nishikawa, Robert M.; Bakic, Predrag R.

    2012-01-01

    Purpose: Digital anthropomorphic breast phantoms have emerged in the past decade because of recent advances in 3D breast x-ray imaging techniques. Computer phantoms in the literature have incorporated power-law noise to represent glandular tissue and branching structures to represent linear components such as ducts. When power-law noise is added to those phantoms in one piece, the simulated fibroglandular tissue is distributed randomly throughout the breast, resulting in dense tissue placement that may not be observed in a real breast. The authors describe a method for enhancing an existing digital anthropomorphic breast phantom by adding binarized power-law noise to a limited area of the breast. Methods: Phantoms with (0.5 mm) 3 voxel size were generated using software developed by Bakic et al. Between 0% and 40% of adipose compartments in each phantom were replaced with binarized power-law noise (β = 3.0) ranging from 0.1 to 0.6 volumetric glandular fraction. The phantoms were compressed to 7.5 cm thickness, then blurred using a 3 × 3 boxcar kernel and up-sampled to (0.1 mm) 3 voxel size using trilinear interpolation. Following interpolation, the phantoms were adjusted for volumetric glandular fraction using global thresholding. Monoenergetic phantom projections were created, including quantum noise and simulated detector blur. Texture was quantified in the simulated projections using power-spectrum analysis to estimate the power-law exponent β from 25.6 × 25.6 mm 2 regions of interest. Results: Phantoms were generated with total volumetric glandular fraction ranging from 3% to 24%. Values for β (averaged per projection view) were found to be between 2.67 and 3.73. Thus, the range of textures of the simulated breasts covers the textures observed in clinical images. Conclusions: Using these new techniques, digital anthropomorphic breast phantoms can be generated with a variety of glandular fractions and patterns. β values for this new phantom are comparable

  13. Construction of an Anthropomorphic Phantom for Use in Evaluating Pediatric Airway Digital Tomosynthesis Protocols

    Directory of Open Access Journals (Sweden)

    Nima Kasraie

    2018-01-01

    Full Text Available Interpretation of radiolucent foreign bodies (FBs is a common task charged to pediatric radiologists. The use of a motion compensated technique to decrease breathing motion on images would greatly decrease overall exposure to ionizing radiation and increase access to treatment yielding a great impact on clinical care. This study reports on the methodology and materials used to construct an in-house anthropomorphic phantom for investigating image quality in digital tomosynthesis protocols for volumetric imaging of the pediatric airway. Availability and cost of possible substitute materials were considered and simplifying assumptions were made. Two different modular phantoms were assembled in coronal slab layers using materials designed to approximate a one- and three-year-old thorax at diagnostic photon energies for use with digital tomosynthesis protocols such as those offered on GE’s VolumeRAD application. Exposures were made using both phantoms with inserted food particles inside an oscillating airway. The goal of the phantom is to help evaluate (1 whether the currently used protocol is sufficient to image the airway despite breathing motion and (2 whether it is not, to find the optimal protocol by testing various commercially available protocols using this phantom. The affordable construction of the pediatric sized phantom aimed at optimizing GE’s VolumeRAD protocol for airway foreign body imaging is demonstrated in this study which can be used to test VolumeRAD’s ability to image the airways with and without a low-density foreign body within the airways.

  14. Skin and cutaneous melanocytic lesion simulation in biomedical optics with multilayered phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Urso, P [Department of Occupational and Environmental Health, Hospital L. Sacco Unit, University of Milan, Via G B Grassi, 74-20157 Milan (Italy); Lualdi, M [Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1-20133 Milan (Italy); Colombo, A [Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1-20133 Milan (Italy); Carrara, M [Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1-20133 Milan (Italy); Tomatis, S [Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1-20133 Milan (Italy); Marchesini, R [Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1-20133 Milan (Italy)

    2007-05-21

    The complex inner layered structure of skin influences the photon diffusion inside the cutaneous tissues and determines the reflectance spectra formation. Phantoms are very useful tools to understand the biophysical meaning of parameters involved in light propagation through the skin. To simulate the skin reflectance spectrum, we realized a multilayered skin-like phantom and a multilayered skin phantom with a melanoma-like phantom embedded inside. Materials used were Al{sub 2}O{sub 3} particles, melanin of sepia officinalis and a calibrator for haematology systems dispersed in transparent silicon. Components were optically characterized with indirect techniques. Reflectance phantom spectra were compared with average values of in vivo spectra acquired on a sample of 573 voluntary subjects and 132 pigmented lesions. The phantoms' reflectance spectra agreed with those measured in vivo, mimicking the optical behaviour of the human skin. Further, the phantoms were optically stable and easily manageable, and represented a valid resource in spectra formation comprehension, in diagnostic laser applications and simulation model implementation, such as the Monte Carlo code for non-homogeneous media. (note)

  15. Skin and cutaneous melanocytic lesion simulation in biomedical optics with multilayered phantoms

    International Nuclear Information System (INIS)

    Urso, P; Lualdi, M; Colombo, A; Carrara, M; Tomatis, S; Marchesini, R

    2007-01-01

    The complex inner layered structure of skin influences the photon diffusion inside the cutaneous tissues and determines the reflectance spectra formation. Phantoms are very useful tools to understand the biophysical meaning of parameters involved in light propagation through the skin. To simulate the skin reflectance spectrum, we realized a multilayered skin-like phantom and a multilayered skin phantom with a melanoma-like phantom embedded inside. Materials used were Al 2 O 3 particles, melanin of sepia officinalis and a calibrator for haematology systems dispersed in transparent silicon. Components were optically characterized with indirect techniques. Reflectance phantom spectra were compared with average values of in vivo spectra acquired on a sample of 573 voluntary subjects and 132 pigmented lesions. The phantoms' reflectance spectra agreed with those measured in vivo, mimicking the optical behaviour of the human skin. Further, the phantoms were optically stable and easily manageable, and represented a valid resource in spectra formation comprehension, in diagnostic laser applications and simulation model implementation, such as the Monte Carlo code for non-homogeneous media. (note)

  16. Monte Carlo simulation of a mammographic test phantom

    International Nuclear Information System (INIS)

    Hunt, R. A.; Dance, D. R.; Pachoud, M.; Carlsson, G. A.; Sandborg, M.; Ullman, G.

    2005-01-01

    A test phantom, including a wide range of mammographic tissue equivalent materials and test details, was imaged on a digital mammographic system. In order to quantify the effect of scatter on the contrast obtained for the test details, calculations of the scatter-to-primary ratio (S/P) have been made using a Monte Carlo simulation of the digital mammographic imaging chain, grid and test phantom. The results show that the S/P values corresponding to the imaging conditions used were in the range 0.084-0.126. Calculated and measured pixel values in different regions of the image were compared as a validation of the model and showed excellent agreement. The results indicate the potential of Monte Carlo methods in the image quality-patient dose process optimisation, especially in the assessment of imaging conditions not available on standard mammographic units. (authors)

  17. Development of digital phantom for DRR evaluation

    International Nuclear Information System (INIS)

    Ikeda, Tsuyoshi; Katsuta, Shoichi; Oyama, Masaya; Ogino, Takashi

    2009-01-01

    Generally, digitally reconstructed radiograph (DRR) is evaluated by physical phantom. The CT image is camouflaged by the performance of the radiation treatment planning system and contains a variety of error factors. The CT image (as follows the digital phantom), where an arbitrary CT value is arranged in the matrix, is necessary to evaluate the pure performance of the radiation treatment planning system. In this study, the development of a digital phantom is described, and the utility is discussed. CTport and the radiation treatment planning system are evaluated with the use of a digital phantom as follows: geometrical accuracy evaluation of DRR, consisting of the center position, size of irradiation field, distortion, extension of X-ray, and beam axis, and the image quality evaluation of DRR, which consists of the contrast resolution. As for DRR made with CTport and the treatment planning system, the part that shifted geometrically was confirmed. In the image quality evaluation, there was a remarkable difference. Because the making accuracy and the installation accuracy of the phantom do not influence the digital phantom, the geometrical accuracy of the DRR is reliable. Because the CT conditions and the phantom factor have no influence, the peculiar DRR image quality can be evaluated and used to evaluate the best image processing parameters. (author)

  18. Analytical expression for the phantom generated bremsstrahlung background in high energy electron beams

    International Nuclear Information System (INIS)

    Sorcini, B.B.; Hyoedynmaa, S; Brahme, A.

    1995-01-01

    Qualification of the bremsstrahlung photon background generated by an electron beam in a phantom is important for accurate high energy electron beam dosimetry in radiation therapy. An analytical expression has been derived for the background of phantom generated bremsstrahlung photons in plane parallel electron beams normally incident on phantoms of any atomic number between 4 and 92 (Be, C, H 2 O, Al, Cu, Ag, Pb and U). The expression can be used with fairly good accuracy in the energy range between 1 and 50 MeV. The expression is globally based on known scattering power and radiation and collision stopping power data for the phantom material at the mean energy of the incident electrons. The depth dose distribution due to the bremsstrahlung generated in the phantom is derived by folding the bremsstrahlung energy fluence with a simple analytical one-dimensional photon energy deposition kernel. The energy loss of the primary electrons and the generation, attenuation and absorption of bremsstrahlung photons are taken into account in the analytical formula. The photon energy deposition kernel is used to account for the bremsstrahlung produced at one depth that will contribute to the down stream dose. A simple analytical expression for photon energy deposition kernel is consistent with the classical analytical relation describing the photon depth dose distribution. From the surface to the practical range the photon dose increases almost linearly due to accumulation and buildup of the photon produced at different phantom layers. At depths beyond the practical range a simple exponential function can be use to describe the bremsstrahlung attenuation in the phantom. For comparison Monte Carlo calculated distributions using ITS3 Monte Carlo Code were used. Good agreement is found between the analytical expression and Monte Carlo calculation. Deviations of 5% from Monte Carlo calculated bremmstrahlung background are observed for high atomic number materials. The method can

  19. Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

    Directory of Open Access Journals (Sweden)

    Jalil Pirayesh Islamian

    2012-03-01

    Full Text Available Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. Materials and Methods The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. Results The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. Conclusion This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection

  20. Charged black holes in phantom cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Mubasher; Qadir, Asghar; Rashid, Muneer Ahmad [National University of Sciences and Technology, Center for Advanced Mathematics and Physics, Rawalpindi (Pakistan)

    2008-11-15

    In the classical relativistic regime, the accretion of phantom-like dark energy onto a stationary black hole reduces the mass of the black hole. We have investigated the accretion of phantom energy onto a stationary charged black hole and have determined the condition under which this accretion is possible. This condition restricts the mass-to-charge ratio in a narrow range. This condition also challenges the validity of the cosmic-censorship conjecture since a naked singularity is eventually produced due to accretion of phantom energy onto black hole. (orig.)

  1. Wormholes supported by phantom energy

    International Nuclear Information System (INIS)

    Gonzalez, J. A.; Guzman, F. S.; Montelongo-Garcia, N.; Zannias, T.

    2009-01-01

    By a combination of analytical and numerical techniques, we demonstrate the existence of spherical, asymptotically flat traversable wormholes supported by exotic matter whose stress tensor relative to the orthonormal frame of Killing observers takes the form of a perfect fluid possessing anisotropic pressures and subject to linear equations of state: τ=λρc 2 , P=μρc 2 . We show that there exists a four parameter family of asymptotically flat spherical wormholes parametrized by the area of the throat A(0), the gradient Λ(0) of the red shift factor evaluated on the throat as well as the values of (λ,μ). The latter are subject to restrictions: λ>1 and 2μ>λ or λ<0 and 2μ<-|λ|. For particular values of (λ,μ), the stress tensor may be interpreted as representing a phantom configuration, while for other values represents exotic matter. All solutions have the property that the two asymptotically flat ends possess finite Arnowitt-Deser-Misner mass.

  2. The role of phantom parameters on the response of the AEOI Neutriran Albedo Neutron Personnel Dosemeter

    International Nuclear Information System (INIS)

    Sohrabi, M.; Katouzi, M.

    1992-01-01

    The response of the AEOI Neutriran Albedo Neutron Personnel Dosemeter (NANPD) which can also be used for other albedo dosemeter types was determined on 18 different phantom configurations. The effects of type, geometry, material, thickness, dosemeter-to-phantom angle in particular with the presence of legs were investigated using a Pu-Be neutron source. It was concluded that the slab phantoms (single or double) and circular and elliptical cylinder phantoms seemed to provide a better response, whereas the ICRU sphere geometry does not seem to be appropriate for the calibration of albedo dosemeters. It is interesting to note that the presence of legs maintains the constancy of the response in a situation when a radiation worker bends down during work. (author)

  3. Calibration of lung counter using a CT model of Torso phantom and Monte Carlo method

    International Nuclear Information System (INIS)

    Zhang Binquan; Ma Jizeng; Yang Duanjie; Liu Liye; Cheng Jianping

    2006-01-01

    Tomography image of a Torso phantom was obtained from CT-Scan. The Torso phantom represents the trunk of an adult man that is 170 cm high and weight of 65 kg. After these images were segmented, cropped, and resized, a 3-dimension voxel phantom was created. The voxel phantom includes more than 2 million voxels, which size was 2.73 mm x 2.73 mm x 3 mm. This model could be used for the calibration of lung counter with Monte Carlo method. On the assumption that radioactive material was homogeneously distributed throughout the lung, counting efficiencies of a HPGe detector in different positions were calculated as Adipose Mass fraction (AMF) was different in the soft tissue in chest. The results showed that counting efficiencies of the lung counter changed up to 67% for 17.5 keV γ ray and 20% for 25 keV γ ray when AMF changed from 0 to 40%. (authors)

  4. Construction of realistic phantoms from patient images and a commercial three-dimensional printer.

    Science.gov (United States)

    Leng, Shuai; Chen, Baiyu; Vrieze, Thomas; Kuhlmann, Joel; Yu, Lifeng; Alexander, Amy; Matsumoto, Jane; Morris, Jonathan; McCollough, Cynthia H

    2016-07-01

    The purpose of this study was to use three-dimensional (3-D) printing techniques to construct liver and brain phantoms having realistic pathologies, anatomic structures, and heterogeneous backgrounds. Patient liver and head computed tomography (CT) images were segmented into tissue, vessels, liver lesion, white and gray matter, and cerebrospinal fluid (CSF). Stereolithography files of each object were created and imported into a commercial 3-D printer. Printing materials were assigned to each object after test scans, which showed that the printing materials had CT numbers ranging from 70 to 121 HU at 120 kV. Printed phantoms were scanned on a CT scanner and images were evaluated. CT images of the liver phantom had measured CT numbers of 77.8 and 96.6 HU for the lesion and background, and 137.5 to 428.4 HU for the vessels channels, which were filled with iodine solutions. The difference in CT numbers between lesions and background (18.8 HU) was representative of the low-contrast values needed for optimization tasks. The liver phantom background was evaluated with Haralick features and showed similar texture between patient and phantom images. CT images of the brain phantom had CT numbers of 125, 134, and 108 HU for white matter, gray matter, and CSF, respectively. The CT number differences were similar to those in patient images.

  5. Phantom cosmology without Big Rip singularity

    Energy Technology Data Exchange (ETDEWEB)

    Astashenok, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation); Nojiri, Shin' ichi, E-mail: nojiri@phys.nagoya-u.ac.jp [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Nagoya 464-8602 (Japan); Odintsov, Sergei D. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Institucio Catalana de Recerca i Estudis Avancats - ICREA and Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Facultat de Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra (Barcelona) (Spain); Tomsk State Pedagogical University, Tomsk (Russian Federation); Yurov, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation)

    2012-03-23

    We construct phantom energy models with the equation of state parameter w which is less than -1, w<-1, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time ('phantom energy' without 'Big Rip' singularity) and (ii) energy density tends to constant value with time ('cosmological constant' with asymptotically de Sitter evolution). The disintegration of bound structure is confirmed in Little Rip cosmology. Surprisingly, we find that such disintegration (on example of Sun-Earth system) may occur even in asymptotically de Sitter phantom universe consistent with observational data. We also demonstrate that non-singular phantom models admit wormhole solutions as well as possibility of Big Trip via wormholes.

  6. Phantom inflation and the 'Big Trip'

    International Nuclear Information System (INIS)

    Gonzalez-Diaz, Pedro F.; Jimenez-Madrid, Jose A.

    2004-01-01

    Primordial inflation is regarded to be driven by a phantom field which is here implemented as a scalar field satisfying an equation of state p=ωρ, with ω-1. Being even aggravated by the weird properties of phantom energy, this will pose a serious problem with the exit from the inflationary phase. We argue, however, in favor of the speculation that a smooth exit from the phantom inflationary phase can still be tentatively recovered by considering a multiverse scenario where the primordial phantom universe would travel in time toward a future universe filled with usual radiation, before reaching the big rip. We call this transition the 'Big Trip' and assume it to take place with the help of some form of anthropic principle which chooses our current universe as being the final destination of the time transition

  7. Phantom cosmology without Big Rip singularity

    International Nuclear Information System (INIS)

    Astashenok, Artyom V.; Nojiri, Shin'ichi; Odintsov, Sergei D.; Yurov, Artyom V.

    2012-01-01

    We construct phantom energy models with the equation of state parameter w which is less than -1, w<-1, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time (“phantom energy” without “Big Rip” singularity) and (ii) energy density tends to constant value with time (“cosmological constant” with asymptotically de Sitter evolution). The disintegration of bound structure is confirmed in Little Rip cosmology. Surprisingly, we find that such disintegration (on example of Sun-Earth system) may occur even in asymptotically de Sitter phantom universe consistent with observational data. We also demonstrate that non-singular phantom models admit wormhole solutions as well as possibility of Big Trip via wormholes.

  8. Analysis of biological tissues in infant chest for the development of an equivalent radiographic phantom

    International Nuclear Information System (INIS)

    Pina, D. R.; Souza, Rafael T. F.; Duarte, Sergio B.; Alvarez, Matheus; Miranda, Jose R. A.

    2012-01-01

    Purpose: The main purpose of the present study was to determine the amounts of different tissues in the chest of the newborn patient (age ≤1 year), with the aim of developing a homogeneous phantom chest equivalent. This type of phantom is indispensable in the development of optimization procedures for radiographic techniques, including dosimetric control, which is a crucial aspect of pediatric radiology. The authors present a systematic set of procedures, including a computational algorithm, to estimate the amounts of tissues and thicknesses of the corresponding simulator material plates used to construct the phantom. Methods: The Gaussian fit of computed tomographic (CT) analysis was applied to classify and quantify different biological tissues. The methodology is summarized with a computational algorithm, which was used to quantify tissues through automated CT analysis. The thicknesses of the equivalent homogeneous simulator material plates were determined to construct the phantom. Results: A total of 180 retrospective CT examinations with anterior-posterior diameter values ranging 8.5-13.0 cm were examined. The amounts of different tissues were evaluated. The results provided elements to construct a phantom to simulate the infant chest in the posterior-anterior or anterior-posterior (PA/AP) view. Conclusions: To our knowledge, this report represents the first demonstration of an infant chest phantom dedicated to the radiology of children younger than one year. This phantom is a key element in the development of clinical charts for optimizing radiographic technique in pediatric patients. Optimization procedures for nonstandard patients were reported previously [Pina et al., Phys. Med. Biol. 49, N215-N226 (2004) and Pina et al., Appl. Radiat. Isot. 67, 61-69 (2009)]. The constructed phantom represents a starting point to obtain radiologic protocols for the infant patient.

  9. 3D printed cardiac phantom for procedural planning of a transcatheter native mitral valve replacement

    Science.gov (United States)

    Izzo, Richard L.; O'Hara, Ryan P.; Iyer, Vijay; Hansen, Rose; Meess, Karen M.; Nagesh, S. V. Setlur; Rudin, Stephen; Siddiqui, Adnan H.; Springer, Michael; Ionita, Ciprian N.

    2016-03-01

    3D printing an anatomically accurate, functional flow loop phantom of a patient's cardiac vasculature was used to assist in the surgical planning of one of the first native transcatheter mitral valve replacement (TMVR) procedures. CTA scans were acquired from a patient about to undergo the first minimally-invasive native TMVR procedure at the Gates Vascular Institute in Buffalo, NY. A python scripting library, the Vascular Modeling Toolkit (VMTK), was used to segment the 3D geometry of the patient's cardiac chambers and mitral valve with severe stenosis, calcific in nature. A stereolithographic (STL) mesh was generated and AutoDesk Meshmixer was used to transform the vascular surface into a functioning closed flow loop. A Stratasys Objet 500 Connex3 multi-material printer was used to fabricate the phantom with distinguishable material features of the vasculature and calcified valve. The interventional team performed a mock procedure on the phantom, embedding valve cages in the model and imaging the phantom with a Toshiba Infinix INFX-8000V 5-axis Carm bi-Plane angiography system. Results: After performing the mock-procedure on the cardiac phantom, the cardiologists optimized their transapical surgical approach. The mitral valve stenosis and calcification were clearly visible. The phantom was used to inform the sizing of the valve to be implanted. Conclusion: With advances in image processing and 3D printing technology, it is possible to create realistic patientspecific phantoms which can act as a guide for the interventional team. Using 3D printed phantoms as a valve sizing method shows potential as a more informative technique than typical CTA reconstruction alone.

  10. Pediatric phantoms for use in dosimetric calculations

    International Nuclear Information System (INIS)

    Shoup, R.L.; Hwang, J.L.; Poston, J.W.; Warner, G.G.

    1976-01-01

    Estimating absorbed doses to children from external and internal radiation sources has become important to the nuclear industry and pediatric nuclear medicine. The Medical Physics and Internal Dosimetry Section at ORNL has recently completed the design of mathematical representations of children of ages newborn, 1 year, and 5 years old. These mathematical representations will be referred to as pediatric phantoms. Using these phantoms, relevant energy deposition data have been developed which establish a meaningful model for use in estimating radiation dose to children

  11. Conversion of ICRP male reference phantom to polygon-surface phantom

    International Nuclear Information System (INIS)

    Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

    2013-01-01

    The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (<2 man-months), we were able to construct the polygon-surface phantom with the organ masses perfectly matching the ICRP reference values. The analysis of the calculated dose values also implies that the dose values are indeed not very sensitive to the detailed morphology of the organ models in the phantom

  12. Mammography dosimetry using an in-house developed polymethyl methacrylate phantom

    International Nuclear Information System (INIS)

    Sharma, R.; Sharma, S. D.; Mayya, Y. S.; Chourasiya, G.

    2012-01-01

    Phantom-based measurements in mammography are well-established for quality assurance (QA) and quality control (QC) procedures involving equipment performance and comparisons of X-ray machines. Polymethyl methacrylate (PMMA) is among the best suitable materials for simulation of the breast. For carrying out QA/QC exercises in India, a mammographic PMMA phantom with engraved slots for keeping thermoluminescence dosemeters (TLD) has been developed. The radiation transmission property of the developed phantom was compared with the commercially available phantoms for verifying its suitability for mammography dosimetry. The breast entrance exposure (BEE), mean glandular dose (MGD), percentage depth dose (PDD), percentage surface dose distribution (PSDD), calibration testing of automatic exposure control (AEC) and density control function of a mammography machine were measured using this phantom. MGD was derived from the measured BEE following two different methodologies and the results were compared. The PDD and PSDD measurements were carried out using LiF: Mg, Cu, P chips. The in-house phantom was found comparable with the commercially available phantoms. The difference in the MGD values derived using two different methods were found in the range of 17.5-32.6 %. Measured depth ranges in the phantom lie between 0.32 and 0.40 cm for 75 % depth dose, 0.73 and 0.92 cm for 50 % depth dose, and 1.54 and 1.78 cm for 25 % depth dose. Higher PSDD value was observed towards chest wall edge side of the phantom, which is due to the orientation of cathode-anode axis along the chest wall to the nipple direction. Results obtained for AEC configuration testing shows that the observed mean optical density (O.D) of the phantom image was 1.59 and O.D difference for every successive increase in thickness of the phantom was within ±0.15 O.D. Under density control function testing, at -2 and -1 density settings, the variation in film image O.D was within ±0.15 O.D of the normal density

  13. Verification of gamma knife based fractionated radiosurgery with newly developed head-thorax phantom

    International Nuclear Information System (INIS)

    Bisht, Raj Kishor; Kale, Shashank Sharad; Natanasabapathi, Gopishankar; Singh, Manmohan Jit; Agarwal, Deepak; Garg, Ajay; Rath, Goura Kishore; Julka, Pramod Kumar; Kumar, Pratik; Thulkar, Sanjay; Sharma, Bhawani Shankar

    2016-01-01

    Objective: Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods: Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results: RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film

  14. Preparing a voxel-simulator of Alderson Rando physical phantom

    International Nuclear Information System (INIS)

    Boia, Leonardo S.; Martins, Maximiano C.; Silva, Ademir X.; Salmon Junior, Helio A.; Soares, Alessandro F.N.S.

    2011-01-01

    There are, nowadays, sorts of anthropomorphycal phantoms which are used for simulation of radiation transport by the matter and also the deposition of energy in such radiation in human tissues and organs, because an in-vitro dosimetry becomes very either complicated or even impossible in some cases. In the present work we prepared a computational phantom in voxels based on computational tomography of Rando-Alderson. This phantom is one of the most known human body simulators on the scope of ionizing radiation dosimetry, and it is used for radioprotection issues and dosimetry from radiotherapy and brachytherapy treatments as well. The preparation of a voxel simulator starts with the image acquisition by a tomograph found at COI/RJ (Clinicas Oncologicas Integradas). The images were generated with 1mm cuts and collected for analysis. After that step the images were processed in SAPDI (Sistema Automatizado de Processamento Digital de Imagem) in order to amplify the images regions intending to facilitate the task in their segmentation. SAPDI is based on parameters described by Hounsfield scale. After that, it has begun discretization of elements in IDs voxels using Scan2MCNP software - which converts images to a sequential text file containing the voxels' IDs ready to be introduced into MCNPX input; however, this set can be turned to a voxel's IDs matrix and used in other Monte Carlo codes, such as Geant4, PENELOPE and EGSnrc. Finished this step, the simulator is able to simulate with accurate geometry the physical phantom. It's possible to study a large number of cases by computational techniques of geometry's insertions of tumors and TLDs, which makes this simulator a research material useful for a lot of subjects. (author)

  15. Preparing a voxel-simulator of Alderson Rando physical phantom

    Energy Technology Data Exchange (ETDEWEB)

    Boia, Leonardo S.; Martins, Maximiano C.; Silva, Ademir X., E-mail: lboia@con.ufrj.br, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear (PEN/COPPE/UFRJ). Universidade Federal do Rio de Janeiro, RJ (Brazil); Salmon Junior, Helio A., E-mail: heliosalmon@coinet.com.br [COI - Clinicas Oncologicas Integradas, MD.X Barra Medical Center, Rio de Janeiro, RJ (Brazil); Soares, Alessandro F.N.S., E-mail: afacure@cnen.gov.br [Comissao Nacional de Engenharia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    There are, nowadays, sorts of anthropomorphycal phantoms which are used for simulation of radiation transport by the matter and also the deposition of energy in such radiation in human tissues and organs, because an in-vitro dosimetry becomes very either complicated or even impossible in some cases. In the present work we prepared a computational phantom in voxels based on computational tomography of Rando-Alderson. This phantom is one of the most known human body simulators on the scope of ionizing radiation dosimetry, and it is used for radioprotection issues and dosimetry from radiotherapy and brachytherapy treatments as well. The preparation of a voxel simulator starts with the image acquisition by a tomograph found at COI/RJ (Clinicas Oncologicas Integradas). The images were generated with 1mm cuts and collected for analysis. After that step the images were processed in SAPDI (Sistema Automatizado de Processamento Digital de Imagem) in order to amplify the images regions intending to facilitate the task in their segmentation. SAPDI is based on parameters described by Hounsfield scale. After that, it has begun discretization of elements in IDs voxels using Scan2MCNP software - which converts images to a sequential text file containing the voxels' IDs ready to be introduced into MCNPX input; however, this set can be turned to a voxel's IDs matrix and used in other Monte Carlo codes, such as Geant4, PENELOPE and EGSnrc. Finished this step, the simulator is able to simulate with accurate geometry the physical phantom. It's possible to study a large number of cases by computational techniques of geometry's insertions of tumors and TLDs, which makes this simulator a research material useful for a lot of subjects. (author)

  16. Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry

    International Nuclear Information System (INIS)

    Bosi, Stephen; Naseri, Pourandokht; Puran, Alicia; Davies, Justin; Baldock, Clive

    2007-01-01

    There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters

  17. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV experimentation

    Directory of Open Access Journals (Sweden)

    Hütter Larissa

    2016-09-01

    Full Text Available Compliant 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.

  18. A dynamic phantom for radionuclide renography

    International Nuclear Information System (INIS)

    Heikkinen, J.O.

    1999-01-01

    The aim of the study was to develop and test a dynamic phantom simulating radionuclide renography. The phantom consisted of five partly lead covered plastic containers simulating kidneys, heart, bladder and background (soft tissues, liver and spleen). Dynamics were performed with multiple movable steel plates between containers and a gamma camera. Control of the plates is performed manually with a stopwatch following exact time schedules. The containers were filled with activities ( 99m Tc) which produce count rates close to clinical situations. Count rates produced by the phantom were compared with ten clinical renography cases: five 99m Tc MAG3 and five 99m Tc DTPA examinations. Two phantom simulations were repeated three times with separate fillings, acquisitions and analyses. Precision errors as a coefficient of variation (CV) of repeated measurements were calculated and theoretical values were compared with the corresponding measured ones. A multicentre comparison was made between 19 nuclear medicine laboratories and three clinical cases were simulated with the phantom. Correlations between count rates produced by the phantom and clinical studies were r=0.964 for 99m Tc MAG3 (p 99m Tc DTPA (p max was 4.0±1.6%. Images and curves of the scanned phantom were close to a real patient in all 19 laboratories but calculated parameters varied: the difference between theoretical and measured values for T max was 6.8±6.2%. The difference between laboratories is most probably due to variations in acquisition protocols and analysis programs: 19 laboratories with 18 different protocols and 8 different programs. The dynamics were found to be repeatable and suitable for calibration purposes for radionuclide renography programs and protocols as well as for multicentre comparisons. (author)

  19. Quantitative computed tomography derived structural geometric accuracy using custom built anthropometric phantom of the proximal femur

    International Nuclear Information System (INIS)

    Khoo, B.C.C.; Price, R.; Hicks, N.

    2011-01-01

    Full text: Material and structural properties influence bone strength. Structural strength may be determined through imaging methods, though currently there is no commercially available phantom to assess structural geometrical (SG) accuracy. This paper describes the design of an anthropometric SG phantom of the proximal femur and the performance testing on quantitative computed tomography (QCT) derived SG outcomes. Aims of study were to determine accuracy of QCT-derived SG outcomes and its effects from kYp. The phantom consists of three basic components; femoral head, a modular and interchangeable neck insert and shaft. The interchangeable neck modules were designed with different cortical thickness and shape. QCT scans were performed with Mindways QA (Mindways Software Inc., USA) phantom, then with anthropometric phantom in water bath together with Mindways calibration phantom. All QCT scans were done on Philips 64 MDCT (Philips Healthcare, USA). Three neck modules were selected and scanned. Each neck module was repeated scanned five times at 120 mAs, 0.67 mm slice thickness and 0.33 mm increment and at 80, 120 and 140 kYps. SG parameters analysed included bone mineral density(aBMD) and outer-diameter (OD).

  20. Construction of voxel head phantom and application to BNCT dose calculation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choon Sik; Lee, Choon Ik; Lee, Jai Ki [Hanyang Univ., Seoul (Korea, Republic of)

    2001-06-15

    Voxel head phantom for overcoming the limitation of mathematical phantom in depicting anatomical details was constructed and example dose calculation for BNCT was performed. The repeated structure algorithm of the general purpose Monte Carlo code, MCNP4B was applied for voxel Monte Carlo calculation. Simple binary voxel phantom and combinatorial geometry phantom composed of two materials were constructed for validating the voxel Monte Carlo calculation system. The tomographic images of VHP man provided by NLM(National Library of Medicine) were segmented and indexed to construct voxel head phantom. Comparison od doses for broad parallel gamma and neutron beams in AP and PA directions showed decrease of brain dose due to the attenuation of neutron in eye balls in case of voxel head phantom. The spherical tumor volume with diameter, 5cm was defined in the center of brain for BNCT dose calculation in which accurate 3 dimensional dose calculation is essential. As a result of BNCT dose calculation for downward neutron beam of 10keV and 40keV, the tumor dose is about doubled when boron concentration ratio between the tumor to the normal tissue is 30{mu}g/g to 3 {mu}g/g. This study established the voxel Monte Carlo calculation system and suggested the feasibility of precise dose calculation in therapeutic radiology.

  1. A Chinese Visible Human-based computational female pelvic phantom for radiation dosimetry simulation

    International Nuclear Information System (INIS)

    Nan, H.; Jinlu, S.; Shaoxiang, Z.; Qing, H.; Li-wen, T.; Chengjun, G.; Tang, X.; Jiang, S. B.; Xiano-lin, Z.

    2010-01-01

    Accurate voxel phantom is needed for dosimetric simulation in radiation therapy for malignant tumors in female pelvic region. However, most of the existing voxel phantoms are constructed on the basis of Caucasian or non-Chinese population. Materials and Methods: A computational framework for constructing female pelvic voxel phantom for radiation dosimetry was performed based on Chinese Visible Human datasets. First, several organs within pelvic region were segmented from Chinese Visible Human datasets. Then, polygonization and voxelization were performed based on the segmented organs and a 3D computational phantom is built in the form of a set of voxel arrays. Results: The generated phantom can be converted and loaded into treatment planning system for radiation dosimetry calculation. From the observed dosimetric results of those organs and structures, we can evaluate their absorbed dose and implement some simulation studies. Conclusion: A voxel female pelvic phantom was developed from Chinese Visible Human datasets. It can be utilized for dosimetry evaluation and planning simulation, which would be very helpful to improve the clinical performance and reduce the radiation toxicity on organ at risk.

  2. 3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method

    International Nuclear Information System (INIS)

    Abella, V.; Miro, R.; Juste, B.; Verdu, G.

    2010-01-01

    The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) 60 Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm 2 . Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized.

  3. Dose distribution in organs: patient-specific phantoms versus reference phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, I.V.B., E-mail: isabelle.lacerda@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Vieira, J.W. [Instituto Federal de Pernambuco (IFPE), Recife (Brazil); Oliveira, M.L.; Lima, F.R.A. [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PB), Recife (Brazil)

    2017-07-01

    Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

  4. Dose distribution in organs: patient-specific phantoms versus reference phantoms

    International Nuclear Information System (INIS)

    Lacerda, I.V.B.; Vieira, J.W.; Oliveira, M.L.; Lima, F.R.A.

    2017-01-01

    Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

  5. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    Energy Technology Data Exchange (ETDEWEB)

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E. [Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland); Centre for Advanced Medical Imaging (CAMI), St James' s Hospital, Dublin 8 (Ireland); Department of Medical Physics, University of Edinburgh, Edinburgh EH16 4TJ (United Kingdom); Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland)

    2011-02-15

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T{sub 1},T{sub 2}) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast

  6. Diffusion Capillary Phantom vs. Human Data: Outcomes for Reconstruction Methods Depend on Evaluation Medium

    Directory of Open Access Journals (Sweden)

    Sarah D. Lichenstein

    2016-09-01

    Full Text Available Purpose: Diffusion MRI provides a non-invasive way of estimating structural connectivity in the brain. Many studies have used diffusion phantoms as benchmarks to assess the performance of different tractography reconstruction algorithms and assumed that the results can be applied to in vivo studies. Here we examined whether quality metrics derived from a common, publically available, diffusion phantom can reliably predict tractography performance in human white matter tissue. Material and Methods: We compared estimates of fiber length and fiber crossing among a simple tensor model (diffusion tensor imaging, a more complicated model (ball-and-sticks and model-free (diffusion spectrum imaging, generalized q-sampling imaging reconstruction methods using a capillary phantom and in vivo human data (N=14. Results: Our analysis showed that evaluation outcomes differ depending on whether they were obtained from phantom or human data. Specifically, the diffusion phantom favored a more complicated model over a simple tensor model or model-free methods for resolving crossing fibers. On the other hand, the human studies showed the opposite pattern of results, with the model-free methods being more advantageous than model-based methods or simple tensor models. This performance difference was consistent across several metrics, including estimating fiber length and resolving fiber crossings in established white matter pathways. Conclusions: These findings indicate that the construction of current capillary diffusion phantoms tends to favor complicated reconstruction models over a simple tensor model or model-free methods, whereas the in vivo data tends to produce opposite results. This brings into question the previous phantom-based evaluation approaches and suggests that a more realistic phantom or simulation is necessary to accurately predict the relative performance of different tractography reconstruction methods. Acronyms: BSM: ball-and-sticks model; d

  7. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    International Nuclear Information System (INIS)

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E.

    2011-01-01

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T 1 ,T 2 ) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow

  8. MCNPX simulation of proton dose distribution in homogeneous and CT phantoms

    International Nuclear Information System (INIS)

    Lee, C.C.; Lee, Y.J.; Tung, C.J.; Cheng, H.W.; Chao, T.C.

    2014-01-01

    A dose simulation system was constructed based on the MCNPX Monte Carlo package to simulate proton dose distribution in homogeneous and CT phantoms. Conversion from Hounsfield unit of a patient CT image set to material information necessary for Monte Carlo simulation is based on Schneider's approach. In order to validate this simulation system, inter-comparison of depth dose distributions among those obtained from the MCNPX, GEANT4 and FLUKA codes for a 160 MeV monoenergetic proton beam incident normally on the surface of a homogeneous water phantom was performed. For dose validation within the CT phantom, direct comparison with measurement is infeasible. Instead, this study took the approach to indirectly compare the 50% ranges (R 50% ) along the central axis by our system to the NIST CSDA ranges for beams with 160 and 115 MeV energies. Comparison result within the homogeneous phantom shows good agreement. Differences of simulated R 50% among the three codes are less than 1 mm. For results within the CT phantom, the MCNPX simulated water equivalent R eq,50% are compatible with the CSDA water equivalent ranges from the NIST database with differences of 0.7 and 4.1 mm for 160 and 115 MeV beams, respectively. - Highlights: ► Proton dose simulation based on the MCNPX 2.6.0 in homogeneous and CT phantoms. ► CT number (HU) conversion to electron density based on Schneider's approach. ► Good agreement among MCNPX, GEANT4 and FLUKA codes in a homogeneous water phantom. ► Water equivalent R 50 in CT phantoms are compatible to those of NIST database

  9. Application of phantoms of the human body for solving radiation protection problems

    International Nuclear Information System (INIS)

    Poulheim, K.F.; Steuer, J.; Fasten, C.

    1977-01-01

    In order to assess the usefulness of various materials (such as polystyrene, crystal sugar and ethanol) as phantom materials for the mean soft tissue, the lung and the skeleton of the ICRP Reference Man, the linear attenuation coefficients for 20, 60, 100 and 134 keV photons have been calculated using an empirical formula. Furthermore, the design and properties of the phantoms used in the Staatliches Amt fuer Atomsicherheit und Strahlenschutz der DDR (SAAS) for calibration and training purposes have been described including some examples of application. (author)

  10. Analysis of the Dose Distribution of Moving Organ using a Moving Phantom System

    International Nuclear Information System (INIS)

    Kim, Yon Lae; Park, Byung Moon; Bae, Yong Ki; Kang, Min Young; Bang, Dong Wan; Lee, Gui Won

    2006-01-01

    Few researches have been performed on the dose distribution of the moving organ for radiotherapy so far. In order to simulate the organ motion caused by respiratory function, multipurpose phantom and moving device was used and dosimetric measurements for dose distribution of the moving organs were conducted in this study. The purpose of our study was to evaluate how dose distributions are changed due to respiratory motion. A multipurpose phantom and a moving device were developed for the measurement of the dose distribution of the moving organ due to respiratory function. Acryl chosen design of the phantom was considered the most obvious choice for phantom material. For construction of the phantom, we used acryl and cork with density of 1.14 g/cm 3 , 0.32 g/cm 3 respectively. Acryl and cork slab in the phantom were used to simulate the normal organ and lung respectively. The moving phantom system was composed of moving device, moving control system, and acryl and cork phantom. Gafchromic film and EDR2 film were used to measure dose distributions. The moving device system may be driven by two directional step motors and able to perform 2 dimensional movements (x, z axis), but only 1 dimensional movement(z axis) was used for this study. Larger penumbra was shown in the cork phantom than in the acryl phantom. The dose profile and isodose curve of Gafchromic EBT film were not uniform since the film has small optical density responding to the dose. As the organ motion was increased, the blurrings in penumbra, flatness, and symmetry were increased. Most of measurements of dose distributions, Gafchromic EBT film has poor flatness and symmetry than EDR2 film, but both penumbra distributions were more or less comparable. The Gafchromic EBT film is more useful as it does not need development and more radiation dose could be exposed than EDR2 film without losing film characteristics. But as response of the optical density of Gafchromic EBT film to dose is low, beam profiles

  11. Cosmological perturbations in transient phantom inflation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Richarte, Martin G. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil); Universidad de Buenos Aires, Ciudad Universitaria 1428, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Kremer, Gilberto M. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil)

    2017-01-15

    We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era. (orig.)

  12. Designing a compact MRI motion phantom

    Directory of Open Access Journals (Sweden)

    Schmiedel Max

    2016-09-01

    Full Text Available Even today, dealing with motion artifacts in magnetic resonance imaging (MRI is a challenging task. Image corruption due to spontaneous body motion complicates diagnosis. In this work, an MRI phantom for rigid motion is presented. It is used to generate motion-corrupted data, which can serve for evaluation of blind motion compensation algorithms. In contrast to commercially available MRI motion phantoms, the presented setup works on small animal MRI systems. Furthermore, retrospective gating is performed on the data, which can be used as a reference for novel motion compensation approaches. The motion of the signal source can be reconstructed using motor trigger signals and be utilized as the ground truth for motion estimation. The proposed setup results in motion corrected images. Moreover, the importance of preprocessing the MRI raw data, e.g. phase-drift correction, is demonstrated. The gained knowledge can be used to design an MRI phantom for elastic motion.

  13. Development and application of a pediatric head phantom for dosimetry in computed tomography

    International Nuclear Information System (INIS)

    Martins, Elaine Wirney

    2016-01-01

    To determine the exposure levels and the absorbed dose in patients undergoing CT scans, is necessary to calculate the CT dose index in measurements with a PMMA or water phantom. The phantom must be enough to simulate the attenuation and scattering characteristics of a human body or parts in a radiation field. The CT specific quantities : CT air kerma index (Ca,100) , weighted CT air kerma index (CW ), a total volume CT air kerma index (Cvol) and the CT air kerma-length product (PKL) must be determined and compared to literature reference levels. In this work a head pediatric phantom was developed, considering that the Brazilian published Diagnostic Reference Levels (DRL) are based on adult phantom measurements. This developed phantom shows a construction innovation using materials to simulate the skullcap, cortical bone (aluminum) and cancellous bone (PVC), and it was filled with distilled water. The phantom dimension follows the recommendations of the World Health Organization and the International Commission on Radiation Units for children from 0 to 5 years old head size: diameter of 160 mm and height of 155 mm. The skullcap has 4 mm of thickness and 111.9 mm of internal diameter. In order to evaluate its behavior, tests were carried out in calibration laboratories and in clinical beams. The results showed attenuation up to 23% when different materials are used as skullcap, demonstrating that the DRLs adopted could be overestimating the dose received by pediatric patients. It is observed that the dose received by CT skull scans presents different distribution, due to the skullcap partially attenuation and/or backscattering which is not considered when the PMMA phantom is used.

  14. Electron beam absorption in solid and in water phantoms: depth scaling and energy-range relations

    International Nuclear Information System (INIS)

    Grosswendt, B.; Roos, M.

    1989-01-01

    In electron dosimetry energy parameters are used with values evaluated from ranges in water. The electron ranges in water may be deduced from ranges measured in solid phantoms. Several procedures recommended by national and international organisations differ both in the scaling of the ranges and in the energy-range relations for water. Using the Monte Carlo method the application of different procedures for electron energies below 10 MeV is studied for different phantom materials. It is shown that deviations in the range scaling and in the energy-range relations for water may accumulate to give energy errors of several per cent. In consequence energy-range relations are deduced for several solid phantom materials which enable a single-step energy determination. (author)

  15. Methodology for the construction of a physical phantom for quality control of images in digital radiography

    International Nuclear Information System (INIS)

    Santos, Tayline T.; Vieira, Jose Wilson; Oliveira, Alex Cristovao H. de; Lima, Fernando R. de Andrade

    2013-01-01

    The advancement of technology in recent years has provided the production of increasingly sophisticated devices, aiming to acquire medical images with high technical level and also facilitate the operational readiness of the equipment. In order to ensure the most accurate diagnosis with minimum dose without exposing patients to obtain data and verify the performance of a radiographic system for quality control purposes we use the so-called phantoms. Phantoms are physical or computational models used to simulate the transport of ionizing radiation, their interactions in the tissues of the human body and evaluate the deposition of energy. Besides, they are made from materials with behavior similar to human tissues when exposed to ionizing radiation - the so-called tissue-equivalent materials. This paper describes the construction of a physical phantom that allows the execution of the main acceptance tests of the quality control protocols in digital radiography

  16. New mechanism to cross the phantom divide

    OpenAIRE

    Du, Yunshuang; Zhang, Hongsheng; Li, Xin-Zhou

    2010-01-01

    Recently, type Ia supernovae data appear to support a dark energy whose equation of state $w$ crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in the gravity with an additional inverse power-law term of Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. So...

  17. Dose evaluation of three-dimensional small animal phantom with film dosimetry

    International Nuclear Information System (INIS)

    Han, Su Chul; Park, Seung Woo

    2017-01-01

    The weight of small animal dosimetry has been continuously increased in pre-clinical studies using radiation in small animals. In this study, three-dimensional(3D) small animal phantom was fabricated using 3D printer which has been continuously used and studied in the various fields. The absorbed dose of 3D animal phantom was evaluated by film dosimetry. Previously, the response of film was obtained from the materials used for production of 3D small animal phantom and compared with the bolus used as the tissue equivalent material in the radiotherapy. When irradiated with gamma rays from 0.5 Gy to 6 Gy, it was confirmed that there was a small difference of less than 1% except 0.5 Gy dose. And when small animal phantom was irradiated with 5 Gy, the difference between the irradiated dose and calculated dose from film was within 2%. Based on this study, it would be possible to increase the reliability of dose in pre-clinical studies using irradiation in small animals by evaluating dose of 3D small animal phantom

  18. Dose evaluation of three-dimensional small animal phantom with film dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Han, Su Chul [Div. of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Park, Seung Woo [Radilogcial and Medico-Oncological Sciences, University of Sciences and Technology, Daejeon (Korea, Republic of)

    2017-03-15

    The weight of small animal dosimetry has been continuously increased in pre-clinical studies using radiation in small animals. In this study, three-dimensional(3D) small animal phantom was fabricated using 3D printer which has been continuously used and studied in the various fields. The absorbed dose of 3D animal phantom was evaluated by film dosimetry. Previously, the response of film was obtained from the materials used for production of 3D small animal phantom and compared with the bolus used as the tissue equivalent material in the radiotherapy. When irradiated with gamma rays from 0.5 Gy to 6 Gy, it was confirmed that there was a small difference of less than 1% except 0.5 Gy dose. And when small animal phantom was irradiated with 5 Gy, the difference between the irradiated dose and calculated dose from film was within 2%. Based on this study, it would be possible to increase the reliability of dose in pre-clinical studies using irradiation in small animals by evaluating dose of 3D small animal phantom.

  19. A phantom for verification of dwell position and time of a high dose rate brachytherapy source

    International Nuclear Information System (INIS)

    Madebo, M.; Kron, T.; Pillainayagam, J.; Franich, R.

    2012-01-01

    Accuracy of dwell position and reproducibility of dwell time are critical in high dose rate (HDR) brachytherapy. A phantom was designed to verify dwell position and dwell time reproducibility for an Ir-192 HDR stepping source using Computed Radiography (CR). The central part of the phantom, incorporating thin alternating strips of lead and acrylic, was used to measure dwell positions. The outer part of the phantom features recesses containing different absorber materials (lead, aluminium, acrylic and polystyrene foam), and was used for determining reproducibility of dwell times. Dwell position errors of <1 mm were easily detectable using the phantom. The effect of bending a transfer tube was studied with this phantom and no change of clinical significance was observed when varying the curvature of the transfer tube in typical clinical scenarios. Changes of dwell time as low as 0.1 s, the minimum dwell time of the treatment unit, could be detected by choosing dwell times over the four materials that produce identical exposure at the CR detector.

  20. WE-D-18A-05: Construction of Realistic Liver Phantoms From Patient Images and a Commercial 3D Printer

    International Nuclear Information System (INIS)

    Leng, S; Vrieze, T; Kuhlmann, J; Yu, L; Matsumoto, J; Morris, J; McCollough, C

    2014-01-01

    Purpose: To assess image quality and radiation dose reduction in abdominal CT imaging, physical phantoms having realistic background textures and lesions are highly desirable. The purpose of this work was to construct a liver phantom with realistic background and lesions using patient CT images and a 3D printer. Methods: Patient CT images containing liver lesions were segmented into liver tissue, contrast-enhanced vessels, and liver lesions using commercial software (Mimics, Materialise, Belgium). Stereolithography (STL) files of each segmented object were created and imported to a 3D printer (Object350 Connex, Stratasys, MN). After test scans were performed to map the eight available printing materials into CT numbers, printing materials were assigned to each object and a physical liver phantom printed. The printed phantom was scanned on a clinical CT scanner and resulting images were compared with the original patient CT images. Results: The eight available materials used to print the liver phantom had CT number ranging from 62 to 117 HU. In scans of the liver phantom, the liver lesions and veins represented in the STL files were all visible. Although the absolute value of the CT number in the background liver material (approx. 85 HU) was higher than in patients (approx. 40 HU), the difference in CT numbers between lesions and background were representative of the low contrast values needed for optimization tasks. Future work will investigate materials with contrast sufficient to emulate contrast-enhanced arteries. Conclusion: Realistic liver phantoms can be constructed from patient CT images using a commercial 3D printer. This technique may provide phantoms able to determine the effect of radiation dose reduction and noise reduction techniques on the ability to detect subtle liver lesions in the context of realistic background textures

  1. WE-D-18A-05: Construction of Realistic Liver Phantoms From Patient Images and a Commercial 3D Printer

    Energy Technology Data Exchange (ETDEWEB)

    Leng, S; Vrieze, T; Kuhlmann, J; Yu, L; Matsumoto, J; Morris, J; McCollough, C [Mayo Clinic, Rochester, MN (United States)

    2014-06-15

    Purpose: To assess image quality and radiation dose reduction in abdominal CT imaging, physical phantoms having realistic background textures and lesions are highly desirable. The purpose of this work was to construct a liver phantom with realistic background and lesions using patient CT images and a 3D printer. Methods: Patient CT images containing liver lesions were segmented into liver tissue, contrast-enhanced vessels, and liver lesions using commercial software (Mimics, Materialise, Belgium). Stereolithography (STL) files of each segmented object were created and imported to a 3D printer (Object350 Connex, Stratasys, MN). After test scans were performed to map the eight available printing materials into CT numbers, printing materials were assigned to each object and a physical liver phantom printed. The printed phantom was scanned on a clinical CT scanner and resulting images were compared with the original patient CT images. Results: The eight available materials used to print the liver phantom had CT number ranging from 62 to 117 HU. In scans of the liver phantom, the liver lesions and veins represented in the STL files were all visible. Although the absolute value of the CT number in the background liver material (approx. 85 HU) was higher than in patients (approx. 40 HU), the difference in CT numbers between lesions and background were representative of the low contrast values needed for optimization tasks. Future work will investigate materials with contrast sufficient to emulate contrast-enhanced arteries. Conclusion: Realistic liver phantoms can be constructed from patient CT images using a commercial 3D printer. This technique may provide phantoms able to determine the effect of radiation dose reduction and noise reduction techniques on the ability to detect subtle liver lesions in the context of realistic background textures.

  2. Finite-element modeling of compression and gravity on a population of breast phantoms for multimodality imaging simulation.

    Science.gov (United States)

    Sturgeon, Gregory M; Kiarashi, Nooshin; Lo, Joseph Y; Samei, E; Segars, W P

    2016-05-01

    The authors are developing a series of computational breast phantoms based on breast CT data for imaging research. In this work, the authors develop a program that will allow a user to alter the phantoms to simulate the effect of gravity and compression of the breast (craniocaudal or mediolateral oblique) making the phantoms applicable to multimodality imaging. This application utilizes a template finite-element (FE) breast model that can be applied to their presegmented voxelized breast phantoms. The FE model is automatically fit to the geometry of a given breast phantom, and the material properties of each element are set based on the segmented voxels contained within the element. The loading and boundary conditions, which include gravity, are then assigned based on a user-defined position and compression. The effect of applying these loads to the breast is computed using a multistage contact analysis in FEBio, a freely available and well-validated FE software package specifically designed for biomedical applications. The resulting deformation of the breast is then applied to a boundary mesh representation of the phantom that can be used for simulating medical images. An efficient script performs the above actions seamlessly. The user only needs to specify which voxelized breast phantom to use, the compressed thickness, and orientation of the breast. The authors utilized their FE application to simulate compressed states of the breast indicative of mammography and tomosynthesis. Gravity and compression were simulated on example phantoms and used to generate mammograms in the craniocaudal or mediolateral oblique views. The simulated mammograms show a high degree of realism illustrating the utility of the FE method in simulating imaging data of repositioned and compressed breasts. The breast phantoms and the compression software can become a useful resource to the breast imaging research community. These phantoms can then be used to evaluate and compare imaging

  3. Results From the Imaging and Radiation Oncology Core Houston's Anthropomorphic Phantoms Used for Proton Therapy Clinical Trial Credentialing

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Paige A., E-mail: pataylor@mdanderson.org; Kry, Stephen F.; Alvarez, Paola; Keith, Tyler; Lujano, Carrie; Hernandez, Nadia; Followill, David S.

    2016-05-01

    Purpose: The purpose of this study was to summarize the findings of anthropomorphic proton phantom irradiations analyzed by the Imaging and Radiation Oncology Core Houston QA Center (IROC Houston). Methods and Materials: A total of 103 phantoms were irradiated by proton therapy centers participating in clinical trials. The anthropomorphic phantoms simulated heterogeneous anatomy of a head, liver, lung, prostate, and spine. Treatment plans included those for scattered, uniform scanning, and pencil beam scanning beam delivery modalities using 5 different treatment planning systems. For every phantom irradiation, point doses and planar doses were measured using thermoluminescent dosimeters (TLD) and film, respectively. Differences between measured and planned doses were studied as a function of phantom, beam delivery modality, motion, repeat attempt, treatment planning system, and date of irradiation. Results: The phantom pass rate (overall, 79%) was high for simple phantoms and lower for phantoms that introduced higher levels of difficulty, such as motion, multiple targets, or increased heterogeneity. All treatment planning systems overestimated dose to the target, compared to TLD measurements. Errors in range calculation resulted in several failed phantoms. There was no correlation between treatment planning system and pass rate. The pass rates for each individual phantom are not improving over time, but when individual institutions received feedback about failed phantom irradiations, pass rates did improve. Conclusions: The proton phantom pass rates are not as high as desired and emphasize potential deficiencies in proton therapy planning and/or delivery. There are many areas for improvement with the proton phantom irradiations, such as treatment planning system dose agreement, range calculations, accounting for motion, and irradiation of multiple targets.

  4. I-125 seed dose estimates in heterogeneous phantom

    International Nuclear Information System (INIS)

    Branco, Isabela S.L.; Antunes, Paula C.G.; Cavalieri, Tassio A.; Moura, Eduardo S.; Zeituni, Carlos A.; Yoriyaz, Helio

    2015-01-01

    Brachytherapy plays an important role in the healing process involving tumors in a variety of diseases. Several studies are currently conducted to examine the heterogeneity effects of different tissues and organs in brachytherapy clinical situations and a great effort has been made to incorporate new methodologies to estimate doses with greater accuracy. The objective of this study is to contribute to the assessment of heterogeneous effects on dose due to I-125 brachytherapy source in the presence of different materials with different densities and chemical compositions. The study was performed in heterogeneous phantoms using materials that simulate human tissues. Among these is quoted: breast, fat, muscle, lungs (exhaled and inhaled) and bones with different densities. Monte Carlo simulations for dose calculation in these phantoms were held and subsequently validated. The model 6711 I-125 seed was considered because it is widely used as a brachytherapy permanent implant and the one used in clinics and hospitals in Brazil. Thermoluminescent dosimeters TLD-700 (LiF: Mg, Ti) were simulated for dose assess. Several tissue configurations and positioning of I-125 sources were studied by simulations for future dose measurements. The methodology of this study so far shall be suitable for accurate dosimetric evaluation for different types of brachytherapy treatments, contributing to brachytherapy planning systems complementation allowing a better assessment of the dose actually delivered to the patient. (author)

  5. I-125 seed dose estimates in heterogeneous phantom

    Energy Technology Data Exchange (ETDEWEB)

    Branco, Isabela S.L.; Antunes, Paula C.G.; Cavalieri, Tassio A.; Moura, Eduardo S.; Zeituni, Carlos A.; Yoriyaz, Helio, E-mail: isabela.slbranco@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Brachytherapy plays an important role in the healing process involving tumors in a variety of diseases. Several studies are currently conducted to examine the heterogeneity effects of different tissues and organs in brachytherapy clinical situations and a great effort has been made to incorporate new methodologies to estimate doses with greater accuracy. The objective of this study is to contribute to the assessment of heterogeneous effects on dose due to I-125 brachytherapy source in the presence of different materials with different densities and chemical compositions. The study was performed in heterogeneous phantoms using materials that simulate human tissues. Among these is quoted: breast, fat, muscle, lungs (exhaled and inhaled) and bones with different densities. Monte Carlo simulations for dose calculation in these phantoms were held and subsequently validated. The model 6711 I-125 seed was considered because it is widely used as a brachytherapy permanent implant and the one used in clinics and hospitals in Brazil. Thermoluminescent dosimeters TLD-700 (LiF: Mg, Ti) were simulated for dose assess. Several tissue configurations and positioning of I-125 sources were studied by simulations for future dose measurements. The methodology of this study so far shall be suitable for accurate dosimetric evaluation for different types of brachytherapy treatments, contributing to brachytherapy planning systems complementation allowing a better assessment of the dose actually delivered to the patient. (author)

  6. Computational anthropomorphic phantoms for radiation protection dosimetry: evolution and prospects

    International Nuclear Information System (INIS)

    Lee, Choonsik; Lee, Jaiki

    2006-01-01

    Computational anthropomorphic phantoms are computer models of human anatomy used in the calculation of radiation dose distribution in the human body upon exposure to a radiation source. Depending on the manner to represent human anatomy, they are categorized into two classes: stylized and tomographic phantoms. Stylized phantoms, which have mainly been developed at the Oak Ridge National Laboratory (ORNL), describe human anatomy by using simple mathematical equations of analytical geometry. Several improved stylized phantoms such as male and female adults, pediatric series, and enhanced organ models have been developed following the first hermaphrodite adult stylized phantom, Medical Internal Radiation Dose (MIRD)-5 phantom. Although stylized phantoms have significantly contributed to dosimetry calculation, they provide only approximations of the true anatomical features of the human body and the resulting organ dose distribution. An alternative class of computational phantom, the tomographic phantom, is based upon three-dimensional imaging techniques such as Magnetic Resonance (MR) imaging and Computed Tomography (CT). The tomographic phantoms represent the human anatomy with a large number of voxels that are assigned tissue type and organ identity. To date, a total of around 30 tomographic phantoms including male and female adults, pediatric phantoms, and even a pregnant female, have been developed and utilized for realistic radiation dosimetry calculation. They are based on MRI/CT images or sectional color photos from patients, volunteers or cadavers. Several investigators have compared tomographic phantoms with stylized phantoms, and demonstrated the superiority of tomographic phantoms in terms of realistic anatomy and dosimetry calculation. This paper summarizes the history and current status of both stylized and tomographic phantoms, including Korean computational phantoms. Advantages, limitations, and future prospects are also discussed

  7. Ultrasonographic Quantification of Fat Content in Fatty Liver Phantoms

    International Nuclear Information System (INIS)

    Kim, Il Young; Kim, Pyo Nyun; Joo, Gyung Soo; Kim, Ho Jung; Kim, Young Beom; Lee, Byoung Ho

    1995-01-01

    Assuming that the fat content of certain tissue might be quantified by measurirrg the ultrasound echo level, we analyzed the ultrasound histograms obtained from the fatty liver phantoms that contained various amount of fat. Various amount of margarine(Mazola. Cliff wood. USA) was mixed with 2% of agarin solution state to produce fatty liver phantoms that contained 5, 10, 20, 30 and 40% of fat. We obtained ultrasound histogram from each fatty liver phantom in gel state. We used 2% agar gel as a control. The ultrasound histograms from the control phantom showed gradual increase in echo level as the depth from the surface increased. The echo level from the phantom that contained 5% of fat showed gradual increase and subsequent decrease with the peak echo level at the depth of 3cm. The echo levels from the phantoms that contained more in 5% of fat gradually decreased as the depth from the surface increased; the change becoming more pronounced as the fat content of the phantom increased. The echo levels measured at the depth of 1cm were 9.3(control), 29.6(5%phantom), 3l.3 (10% phantom), 26.3 (20% phantom), l8.8 (30% phantom), and l6dB (40% phantom). Fat content of fatty phantoms can not be quantified by measuring only echo level. Simultaneous measurement of attenuation of ultrasound, which is not easy to do and not done in this study, is prerequisite to quantify fat content

  8. Tissue quantification for development of pediatric phantom

    International Nuclear Information System (INIS)

    Alves, A.F.F.; Miranda, J.R.A.; Pina, D.R.

    2013-01-01

    The optimization of the risk- benefit ratio is a major concern in the pediatric radiology, due to the greater vulnerability of children to the late somatic effects and genetic effects of exposure to radiation compared to adults. In Brazil, it is estimated that the causes of death from head trauma are 18 % for the age group between 1-5 years and the radiograph is the primary diagnostic test for the detection of skull fracture . Knowing that the image quality is essential to ensure the identification of structures anatomical and minimizing errors diagnostic interpretation, this paper proposed the development and construction of homogeneous phantoms skull, for the age group 1-5 years. The construction of the phantoms homogeneous was performed using the classification and quantification of tissue present in the skull of pediatric patients. In this procedure computational algorithms were used, using Matlab, to quantify distinct biological tissues present in the anatomical regions studied , using pictures retrospective CT scans. Preliminary data obtained from measurements show that between the ages of 1-5 years, assuming an average anteroposterior diameter of the pediatric skull region of the 145.73 ± 2.97 mm, can be represented by 92.34 mm ± 5.22 of lucite and 1.75 ± 0:21 mm of aluminum plates of a provision of PEP (Pacient equivalent phantom). After its construction, the phantoms will be used for image and dose optimization in pediatric protocols process to examinations of computerized radiography

  9. PHANTOM: Smoothed particle hydrodynamics and magnetohydrodynamics code

    Science.gov (United States)

    Price, Daniel J.; Wurster, James; Nixon, Chris; Tricco, Terrence S.; Toupin, Stéven; Pettitt, Alex; Chan, Conrad; Laibe, Guillaume; Glover, Simon; Dobbs, Clare; Nealon, Rebecca; Liptai, David; Worpel, Hauke; Bonnerot, Clément; Dipierro, Giovanni; Ragusa, Enrico; Federrath, Christoph; Iaconi, Roberto; Reichardt, Thomas; Forgan, Duncan; Hutchison, Mark; Constantino, Thomas; Ayliffe, Ben; Mentiplay, Daniel; Hirsh, Kieran; Lodato, Giuseppe

    2017-09-01

    Phantom is a smoothed particle hydrodynamics and magnetohydrodynamics code focused on stellar, galactic, planetary, and high energy astrophysics. It is modular, and handles sink particles, self-gravity, two fluid and one fluid dust, ISM chemistry and cooling, physical viscosity, non-ideal MHD, and more. Its modular structure makes it easy to add new physics to the code.

  10. Homemade ultrasound phantom for simulation of hydronephrosis

    Directory of Open Access Journals (Sweden)

    Ana Karine Brandao Novaes

    2018-05-01

    Full Text Available Abstract In this article, we describe the development of a simple and inexpensive simulation phantom as a surrogate of human hydronephrosis for the identification of urinary tract obstruction at bedside to be used in undergraduate training of medical students.

  11. The "Phantom Costs" of Florida's Citrus Industry

    OpenAIRE

    Muraro, Ronald P.; Roka, Fritz M.; Spreen, Thomas H.

    2006-01-01

    Regulatory compliance, the "phantom costs of production," is an increasingly "fact-of-life" for U.S. agriculture. A survey was developed and implemented to enumerate regulatory compliance costs for Florida's 748,500 acres citrus industry. Complying with 61 production related regulations, 643,757 hours were expended at a total annual cost of over $24.3 million.

  12. IMRT delivery verification using a spiral phantom

    International Nuclear Information System (INIS)

    Richardson, Susan L.; Tome, Wolfgang A.; Orton, Nigel P.; McNutt, Todd R.; Paliwal, Bhudatt R.

    2003-01-01

    In this paper we report on the testing and verification of a system for IMRT delivery quality assurance that uses a cylindrical solid water phantom with a spiral trajectory for radiographic film placement. This spiral film technique provides more complete dosimetric verification of the entire IMRT treatment than perpendicular film methods, since it samples a three-dimensional dose subspace rather than using measurements at only one or two depths. As an example, the complete analysis of the predicted and measured spiral films is described for an intracranial IMRT treatment case. The results of this analysis are compared to those of a single field perpendicular film technique that is typically used for IMRT QA. The comparison demonstrates that both methods result in a dosimetric error within a clinical tolerance of 5%, however the spiral phantom QA technique provides a more complete dosimetric verification while being less time consuming. To independently verify the dosimetry obtained with the spiral film, the same IMRT treatment was delivered to a similar phantom in which LiF thermoluminescent dosimeters were arranged along the spiral trajectory. The maximum difference between the predicted and measured TLD data for the 1.8 Gy fraction was 0.06 Gy for a TLD located in a high dose gradient region. This further validates the ability of the spiral phantom QA process to accurately verify delivery of an IMRT plan

  13. Phantom breast sensations are frequent after mastectomy

    DEFF Research Database (Denmark)

    Hansen, Dorthe Marie Helbo; Kehlet, Henrik; Gærtner, Rune

    2011-01-01

    Phantom breast sensation (PBS) following mastectomy has been recognized for many years. PBS is a feeling that the removed breast is still there. The reported prevalence and risk factors have not been established in large well-defined patient series. The purpose of this study was to examine...... the prevalence of PBS following mastectomy and associated risk factors....

  14. Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy

    International Nuclear Information System (INIS)

    Thompson, Larissa

    2013-01-01

    Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

  15. Materialism.

    Science.gov (United States)

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website. Copyright © 2012 John Wiley & Sons, Ltd.

  16. Development and implementation of an anthropomorphic pediatric spine phantom for the assessment of craniospinal irradiation procedures in proton therapy

    OpenAIRE

    Dana J Lewis; Paige A Summers; David S Followill; Narayan Sahoo; Anita Mahajan; Francesco C Stingo; Stephen F Kry

    2014-01-01

    Purpose: To design an anthropomorphic pediatric spine phantom for use in the evaluation of proton therapy facilities for clinical trial participation by the Imaging and Radiation Oncology Core (IROC) Houston QA Center (formerly RPC).Methods: This phantom was designed to perform an end-to-end audit of the proton spine treatment process, including simulation, dose calculation by the treatment planning system (TPS), and proton treatment delivery. The design incorporated materials simulating the ...

  17. Challenges and limitations of patient-specific vascular phantom fabrication using 3D Polyjet printing

    Science.gov (United States)

    Ionita, Ciprian N.; Mokin, Maxim; Varble, Nicole; Bednarek, Daniel R.; Xiang, Jianping; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui; Rudin, Stephen

    2014-03-01

    Additive manufacturing (3D printing) technology offers a great opportunity towards development of patient-specific vascular anatomic models, for medical device testing and physiological condition evaluation. However, the development process is not yet well established and there are various limitations depending on the printing materials, the technology and the printer resolution. Patient-specific neuro-vascular anatomy was acquired from computed tomography angiography and rotational digital subtraction angiography (DSA). The volumes were imported into a Vitrea 3D workstation (Vital Images Inc.) and the vascular lumen of various vessels and pathologies were segmented using a "marching cubes" algorithm. The results were exported as Stereo Lithographic (STL) files and were further processed by smoothing, trimming, and wall extrusion (to add a custom wall to the model). The models were printed using a Polyjet printer, Eden 260V (Objet-Stratasys). To verify the phantom geometry accuracy, the phantom was reimaged using rotational DSA, and the new data was compared with the initial patient data. The most challenging part of the phantom manufacturing was removal of support material. This aspect could be a serious hurdle in building very tortuous phantoms or small vessels. The accuracy of the printed models was very good: distance analysis showed average differences of 120 μm between the patient and the phantom reconstructed volume dimensions. Most errors were due to residual support material left in the lumen of the phantom. Despite the post-printing challenges experienced during the support cleaning, this technology could be a tremendous benefit to medical research such as in device development and testing.

  18. Deep brain stimulation for phantom limb pain.

    Science.gov (United States)

    Bittar, Richard G; Otero, Sofia; Carter, Helen; Aziz, Tipu Z

    2005-05-01

    Phantom limb pain is an often severe and debilitating phenomenon that has been reported in up to 85% of amputees. Its pathophysiology is poorly understood. Peripheral and spinal mechanisms are thought to play a role in pain modulation in affected individuals; however central mechanisms are also likely to be of importance. The neuromatrix theory postulates a genetically determined representation of body image, which is modified by sensory input to create a neurosignature. Persistence of the neurosignature may be responsible for painless phantom limb sensations, whereas phantom limb pain may be due to abnormal reorganisation within the neuromatrix. This study assessed the clinical outcome of deep brain stimulation of the periventricular grey matter and somatosensory thalamus for the relief of chronic neuropathic pain associated with phantom limb in three patients. These patients were assessed preoperatively and at 3 month intervals postoperatively. Self-rated visual analogue scale pain scores assessed pain intensity, and the McGill Pain Questionnaire assessed the quality of the pain. Quality of life was assessed using the EUROQOL EQ-5D scale. Periventricular gray stimulation alone was optimal in two patients, whilst a combination of periventricular gray and thalamic stimulation produced the greatest degree of relief in one patient. At follow-up (mean 13.3 months) the intensity of pain was reduced by 62% (range 55-70%). In all three patients, the burning component of the pain was completely alleviated. Opiate intake was reduced in the two patients requiring morphine sulphate pre-operatively. Quality of life measures indicated a statistically significant improvement. This data supports the role for deep brain stimulation in patients with phantom limb pain. The medical literature relating to the epidemiology, pathogenesis, and treatment of this clinical entity is reviewed in detail.

  19. Image fusion tool: Validation by phantom measurements

    International Nuclear Information System (INIS)

    Zander, A.; Geworski, L.; Richter, M.; Ivancevic, V.; Munz, D.L.; Muehler, M.; Ditt, H.

    2002-01-01

    Aim: Validation of a new image fusion tool with regard to handling, application in a clinical environment and fusion precision under different acquisition and registration settings. Methods: The image fusion tool investigated allows fusion of imaging modalities such as PET, CT, MRI. In order to investigate fusion precision, PET and MRI measurements were performed using a cylinder and a body contour-shaped phantom. The cylinder phantom (diameter and length 20 cm each) contained spheres (10 to 40 mm in diameter) which represented 'cold' or 'hot' lesions in PET measurements. The body contour-shaped phantom was equipped with a heart model containing two 'cold' lesions. Measurements were done with and without four external markers placed on the phantoms. The markers were made of plexiglass (2 cm diameter and 1 cm thickness) and contained a Ga-Ge-68 core for PET and Vitamin E for MRI measurements. Comparison of fusion results with and without markers was done visually and by computer assistance. This algorithm was applied to the different fusion parameters and phantoms. Results: Image fusion of PET and MRI data without external markers yielded a measured error of 0 resulting in a shift at the matrix border of 1.5 mm. Conclusion: The image fusion tool investigated allows a precise fusion of PET and MRI data with a translation error acceptable for clinical use. The error is further minimized by using external markers, especially in the case of missing anatomical orientation. Using PET the registration error depends almost only on the low resolution of the data

  20. Reconstruction of voxel phantoms for skin dosimetry

    International Nuclear Information System (INIS)

    Antunes, Paula Cristina Guimaraes

    2010-01-01

    Radiotherapy is a therapeutic modality that utilizes ionizing radiation for the destruction of neoplastic human cells. One of the requirements for this treatment methodology success lays on the appropriate use of planning systems, which performs, among other information, the patient's dose distribution estimate. Nowadays, transport codes have been providing huge subsidies to these planning systems, once it enables specific and accurate patient organ and tissue dosimetry. The model utilized by these codes to describe the human anatomy in a realistic way is known as voxel phantoms, which are represented by discrete volume elements (voxels) directly associated to tomographic data. Nowadays, voxel phantoms doable of being inserted and processed by the transport code MCNP (Monte Carlo N-Particle) presents a 3-4 mm image resolution; however, such resolution limits some thin body structure discrimination, such as skin. In this context, this work proposes a calculus routine that discriminates this region with thickness and localization in the voxel phantoms similar to the real, leading to an accurate dosimetric skin dose assessment by the MCNP code. Moreover, this methodology consists in manipulating the voxel phantoms volume elements by segmenting and subdividing it in different skin thickness. In addition to validate the skin dose calculated data, a set of experimental evaluations with thermoluminescent dosimeters were performed in an anthropomorphic phantom. Due to significant differences observed on the dose distribution of several skin representations, it was found that is important to discriminate the skin thickness similar to the real. The presented methodology is useful to obtain an accurate skin dosimetric evaluation for several radiotherapy procedures, with particular interest on the electron beam radiotherapy, in which highlights the whole body irradiation therapy (TSET), a procedure under implementation at the Hospital das Clinicas da Faculdade de Medicina da

  1. Phantom Sensations, Supernumerary Phantom Limbs and Apotemnophilia: Three Body Representation Disorders.

    Science.gov (United States)

    Tatu, Laurent; Bogousslavsky, Julien

    2018-01-01

    Body representation disorders continue to be mysterious and involve the anatomical substrate that underlies the mental representation of the body. These disorders sit on the boundaries of neurological and psychiatric diseases. We present the main characteristics of 3 examples of body representation disorders: phantom sensations, supernumerary phantom limb, and apotemnophilia. The dysfunction of anatomical circuits that regulate body representation can sometimes have paradoxical features. In the case of phantom sensations, the patient feels the painful subjective sensation of the existence of the lost part of the body after amputation, surgery or trauma. In case of apotemnophilia, now named body integrity identity disorder, the subject wishes for the disappearance of the existing and normal limb, which can occasionally lead to self-amputation. More rarely, a brain-damaged patient with 4 existing limbs can report the existence of a supernumerary phantom limb. © 2018 S. Karger AG, Basel.

  2. Biopsy guided by real-time sonography fused with MRI: a phantom study

    DEFF Research Database (Denmark)

    Ewertsen, C.; Grossjohann, Hanne Sønder; Nielsen, Kristina Rue

    2008-01-01

    OBJECTIVE: The purpose of our study was to test the accuracy of sonographically guided biopsies in a phantom of structures not visible on sonography but shown on MRI by using commercially available sonography systems with image fusion software. MATERIALS AND METHODS: A previously recorded MRI...

  3. Intercomparison of JAERI Torso Phantom lung sets

    International Nuclear Information System (INIS)

    Kramer, Gary H.; Hauck, Barry M.

    2000-01-01

    During the course of an IAEA sponsored In Vivo intercomparison using the JAERI phantom the Human Monitoring Laboratory was able to intercompare thirteen lung sets made by three suppliers. One set consisted of sliced lungs with planar inserts containing different radionuclides. The others consisted of whole lung sets with the activity homogeneously distributed throughout the tissue substitute material. Radionuclides in the study were: natural uranium, 3% enriched uranium, 241 Am, 238 Pu, 239 Pu, 152 Eu, and 232 Th Except for the 241 Am (59.5 keV) and occasionally one of the 232 Th (209 keV) photopeaks, the lung sets that had radioactivity homogeneously distributed throughout the tissue equivalent lung tissue material showed good agreement. The 241 Am lung set gave a counting efficiency that appeared 25% too high for all overlay plate configurations. This was observed by other participants. It exemplifies that the manufacture of tissue substitute lung sets is still something of a black art. Despite all precautions, this lung set is either inhomogeneous or has had the wrong activity added. Heterogeneity can lead to an error in the activity estimate of a factor of three if the activity was severely localised due to improper mixing. A factor of 1.25, which appears to be the discrepancy, could easily be explained in this way. It will not be known for some time, however, what the true reason is as the participants are still waiting for the destructive analysis of this lung set to determine the 'true' activity. The sliced lungs ( 241 Am, 152 Eu, and U-nat) manufactured by the Human Monitoring Laboratory are in excellent agreement with the other lung sets. The advantages of sliced lung sets and planar sources are manifold. Activity can be distributed in a known and reproducible manner to mimic either a homogeneous or heterogeneous distribution in the lung. Short lived radionuclides can be used. Cost is much less than purchasing or manufacturing lung sets that have the

  4. MRI quality assurance using the ACR phantom in a multi-unit imaging center

    International Nuclear Information System (INIS)

    Ihalainen, Toni M.; Kuusela, Linda J.; Savolainen, Sauli E.; Loennroth, Nadja T.; Peltonen, Juha I.; Uusi-Simola, Jouni K.; Timonen, Marjut H.; Sipilae, Outi E.

    2011-01-01

    Background. Magnetic resonance imaging (MRI) instrumentation is vulnerable to technical and image quality problems, and quality assurance is essential. In the studied regional imaging center the long-term quality assurance has been based on MagNET phantom measurements. American College of Radiology (ACR) has an accreditation program including a standardized image quality measurement protocol and phantom. The ACR protocol includes recommended acceptance criteria for clinical sequences and thus provides possibility to assess the clinical relevance of quality assurance. The purpose of this study was to test the ACR MRI phantom in quality assurance of a multi-unit imaging center. Material and methods. The imaging center operates 11 MRI systems of three major manufacturers with field strengths of 3.0 T, 1.5 T and 1.0 T. Images of the ACR phantom were acquired using a head coil following the ACR scanning instructions. Both ACR T1- and T2-weighted sequences as well as T1- and T2-weighted brain sequences in clinical use at each site were acquired. Measurements were performed twice. The images were analyzed and the results were compared with the ACR acceptance levels. Results. The acquisition procedure with the ACR phantom was faster than with the MagNET phantoms. On the first and second measurement rounds 91% and 73% of the systems passed the ACR test. Measured slice thickness accuracies were not within the acceptance limits in site T2 sequences. Differences in the high contrast spatial resolution between the ACR and the site sequences were observed. In 3.0 T systems the image intensity uniformity was slightly lower than the ACR acceptance limit. Conclusion. The ACR method was feasible in quality assurance of a multi-unit imaging center and the ACR protocol could replace the MagNET phantom tests. An automatic analysis of the images will further improve cost-effectiveness and objectiveness of the ACR protocol

  5. Experimental study on representation of flow on the bifurcated carotid arterial phantoms using magnetic resonance angiography

    International Nuclear Information System (INIS)

    Chung, Tae Sub; Rhim, Yoon Chul; Kim, Kyung Oh; Suh, Sang Ho; Jin, En Hao

    1995-01-01

    A common finding of carotid artery on magnetic resonance angiograms(MRAs) is a signal dropout along the posterior wall of carotid bulb due to reverse flow. The purpose of this study is to evaluate variable flow patterns on bifurcated carotid arterial phantoms using steady-state flow. We designed phantoms of a bifurcated carotid artery with acrylic materials. Flow patterns were evaluated with axial and coronal imaging of MRA(2D-TOF, 3D-TOF), color Doppler imaging, and computational fluid dynamics (CFD) within the phantoms constructed of an automated closed-type circulatory system filled with 4% sugar solution. These findings were compared with findings obtained from normal volunteers. Axial 3D-TOF MRA images exhibited closer resemblance to the contour of the inner wall of phantoms when compared to coronal 2D-TOF MRA imaging. However, 2D-TOF MRA showed good contrast difference of signal intensities between forward flow area and reverse flow area. Dark zones with reduced signal intensities due to reversed flow were separated from the outer wall of the internal and external carotid arteries by a thin layer of forward flow along the wall on the source slice image of MRA. The general hemodynamics of the phantoms on MRA were identical to hemodynamics on color Doppler imaging and CFD. The results obtained with the phantoms matched the findings on normal volunteers. Although representations of bifurcated carotid arterial phantoms on axial 3D-TOF MRA were excellent if ideally designed, the zone of reversed flow could be a significant factor in creating distorted image when the zone of reversed flow contacted directly with curved or deformed arterial wall

  6. Image based Monte Carlo modeling for computational phantom

    International Nuclear Information System (INIS)

    Cheng, M.; Wang, W.; Zhao, K.; Fan, Y.; Long, P.; Wu, Y.

    2013-01-01

    Full text of the publication follows. The evaluation on the effects of ionizing radiation and the risk of radiation exposure on human body has been becoming one of the most important issues for radiation protection and radiotherapy fields, which is helpful to avoid unnecessary radiation and decrease harm to human body. In order to accurately evaluate the dose on human body, it is necessary to construct more realistic computational phantom. However, manual description and verification of the models for Monte Carlo (MC) simulation are very tedious, error-prone and time-consuming. In addition, it is difficult to locate and fix the geometry error, and difficult to describe material information and assign it to cells. MCAM (CAD/Image-based Automatic Modeling Program for Neutronics and Radiation Transport Simulation) was developed as an interface program to achieve both CAD- and image-based automatic modeling. The advanced version (Version 6) of MCAM can achieve automatic conversion from CT/segmented sectioned images to computational phantoms such as MCNP models. Imaged-based automatic modeling program(MCAM6.0) has been tested by several medical images and sectioned images. And it has been applied in the construction of Rad-HUMAN. Following manual segmentation and 3D reconstruction, a whole-body computational phantom of Chinese adult female called Rad-HUMAN was created by using MCAM6.0 from sectioned images of a Chinese visible human dataset. Rad-HUMAN contains 46 organs/tissues, which faithfully represented the average anatomical characteristics of the Chinese female. The dose conversion coefficients (Dt/Ka) from kerma free-in-air to absorbed dose of Rad-HUMAN were calculated. Rad-HUMAN can be applied to predict and evaluate dose distributions in the Treatment Plan System (TPS), as well as radiation exposure for human body in radiation protection. (authors)

  7. A trial preparation of phantom for use in both x-ray computed tomography and ultrasonography

    International Nuclear Information System (INIS)

    Kimura, Kazue; Katakura, Toshihiko; Ito, Masami; Suzuki, Kenji; Hoshi, Koji

    1983-01-01

    Effective clinical diagnosis by XCT and US may be assisted by prior evaluation of basic data with an experimental phantom that can be used in both XCT and US. This paper describes a phantom prepared for this purpose. Materials are warm water, gelatine powder, powder soap (containing 98% surface active agent) and salad oil. Table 1 shows the recipe. Gelatine powder is first dissolved in warm water, to which powder soap and salad oil are added. After sufficient stirring, the mixture is placed into a vessel and allowed to stand 24 hours for solidification. (author)

  8. Phantom energy accretion onto black holes in a cyclic universe

    International Nuclear Information System (INIS)

    Sun Chengyi

    2008-01-01

    Black holes pose a serious problem in cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by phantom energy prior to turnaround before they can create any problems. In this paper, using the mechanism of phantom accretion onto black holes, we find that black holes do not disappear before phantom turnaround. But the remanent black holes will not cause any problems due to Hawking evaporation.

  9. Hybrid pregnant reference phantom series based on adult female ICRP reference phantom

    Science.gov (United States)

    Rafat-Motavalli, Laleh; Miri-Hakimabad, Hashem; Hoseinian-Azghadi, Elie

    2018-03-01

    This paper presents boundary representation (BREP) models of pregnant female and her fetus at the end of each trimester. The International Commission on Radiological Protection (ICRP) female reference voxel phantom was used as a base template in development process of the pregnant hybrid phantom series. The differences in shape and location of the displaced maternal organs caused by enlarging uterus were also taken into account. The CT and MR images of fetus specimens and pregnant patients of various ages were used to replace the maternal abdominal pelvic organs of template phantom and insert the fetus inside the gravid uterus. Each fetal model contains 21 different organs and tissues. The skeletal model of the fetus also includes age-dependent cartilaginous and ossified skeletal components. The replaced maternal organ models were converted to NURBS surfaces and then modified to conform to reference values of ICRP Publication 89. The particular feature of current series compared to the previously developed pregnant phantoms is being constructed upon the basis of ICRP reference phantom. The maternal replaced organ models are NURBS surfaces. With this great potential, they might have the feasibility of being converted to high quality polygon mesh phantoms.

  10. Electrical Impedance Spectroscopic Studies on Broiler Chicken Tissue Suitable for the Development of Practical Phantoms in Multifrequency EIT

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bera

    2011-06-01

    Full Text Available Phantoms are essential for assessing the system performance in Electrical Impedance Tomography (EIT. Saline phantoms with insulator inhomogeneity fail to mimic the physiological structure of real body tissue in several aspects. Saline or any other salt solutions are purely resistive and hence studying multifrequency EIT systems cannot be assessed with saline phantoms because the response of the purely resistive materials do not change over frequency. Animal tissues show a variable response over a wide band of signal frequency due to their complex physiological and physiochemical structures and hence they can suitably be used as bathing medium and inhomogeneity in the phantoms of multifrequency EIT system. An efficient assessment of a multifrequency EIT system with real tissue phantom needs a prior knowledge of the impedance profile of the bathing medium as well as the inhomogeneity. In this direction Electrical Impedance Spectroscopy (EIS of broiler chicken muscle tissue paste and broiler chicken fat tissue is conducted from 10 Hz to 2 MHz using an impedance analyzer and their impedance profiles are thoroughly studied. Results show that the broiler chicken muscle tissue paste is less resistive than the fat tissue and hence it can be successfully used as the bathing medium of the phantoms for resistivity imaging in multifrequency EIT. Fat tissue is found more resistive than the muscle tissue which makes it more suitable for the inhomogeneity in phantoms of resistivity imaging study. doi:10.5617/jeb.174 J Electr Bioimp, vol. 2, pp. 48-63, 2011

  11. ICRU activity in the field of phantoms in diagnostic radiology

    International Nuclear Information System (INIS)

    Wambersie, A.

    1992-01-01

    The ICRU Report on 'Phantoms and Computational Models in Radiation Therapy, Diagnosis and Protection' is presented. Different types of phantoms may be defined. They may be broadly categorized according to their primary function: dosimetry, calibration and imaging. Within each functional category, there are 3 types or designs of phantoms: body phantoms (anthropomorphic), standard phantoms and reference phantoms (used in the definition and specification of certain radiation quantities). In radiological imaging, anthropomorphic body phantoms are used for measuring the absorbed dose distribution resulting from imaging procedures. Standard phantoms have simple reproducible geometry and are used for comparing measurements under standard conditions of exposure. Imaging phantoms are useful for evaluating a given imaging system; they contain different types of test pieces. The report contains a major section on human anatomy, from fetus to adult with the variations due to ethnic origin. Tolerance levels for the phantoms (composition, dimensions) are proposed and quality assurance programs are outlined. The report contains extensive appendices; human anatomical data and full specification of over 80 phantoms and computational models. ICRU Report 46 on 'Photon, electron, proton and neutron interaction data for body tissues' is closely related to the field of phantoms. It is a logical continuation on ICRU Report 44 (1989) on 'Tissue substitutes in radiation dosimetry and measurements' and contains the interaction data for more than 100 tissues, from fetal to adult, including some diseased tissues

  12. A multileaf collimator phantom for the quality assurance of radiation therapy planning systems and CT simulators

    International Nuclear Information System (INIS)

    McNiven, Andrea; Kron, Tomas; Van Dyk, Jake

    2004-01-01

    Purpose: The evolution of three-dimensional conformal radiation treatment has led to the use of multileaf collimators (MLCs) in intensity-modulated radiation therapy (IMRT) and other treatment techniques to increase the conformity of the dose distribution. A new quality assurance (QA) phantom has been designed to check the handling of MLC settings in treatment planning and delivery. Methods and materials: The phantom consists of a Perspex block with stepped edges that can be rotated in all planes. The design allows for the assessment of several MLC and micro-MLC types from various manufacturers, and is therefore applicable to most radiation therapy institutions employing MLCs. The phantom is computed tomography (CT) scanned as is a patient, and QA assessments can be made of field edge display for a variety of shapes and orientations on both radiation treatment planning systems (RTPS) and computed tomography simulators. Results: The dimensions of the phantom were verified to be physically correct within an uncertainty range of 0-0.7 mm. Errors in leaf position larger than 1 mm were easily identified by multiple observers. Conclusions: The MLC geometry phantom is a useful tool in the QA of radiation therapy with application to RTPS, CT simulators, and virtual simulation packages with MLC display capabilities

  13. Analysis of translational errors in frame-based and frameless cranial radiosurgery using an anthropomorphic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Taynna Vernalha Rocha [Faculdades Pequeno Principe (FPP), Curitiba, PR (Brazil); Cordova Junior, Arno Lotar; Almeida, Cristiane Maria; Piedade, Pedro Argolo; Silva, Cintia Mara da, E-mail: taynnavra@gmail.com [Centro de Radioterapia Sao Sebastiao, Florianopolis, SC (Brazil); Brincas, Gabriela R. Baseggio [Centro de Diagnostico Medico Imagem, Florianopolis, SC (Brazil); Marins, Priscila; Soboll, Danyel Scheidegger [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2016-03-15

    Objective: To evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom. Materials and Methods: We initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART)-210 anthropomorphic head phantom, into which we inserted four 5- mm metal balls to simulate target treatment volumes. Computed tomography images were the taken with the head phantom properly positioned for frameless and frame-based radiosurgery. Results: For the frameless technique, the mean error magnitude was 0.22 ± 0.04 mm for setup errors and 0.14 ± 0.02 mm for residual errors, the combined uncertainty being 0.28 mm and 0.16 mm, respectively. For the frame-based technique, the mean error magnitude was 0.73 ± 0.14 mm for setup errors and 0.31 ± 0.04 mm for residual errors, the combined uncertainty being 1.15 mm and 0.63 mm, respectively. Conclusion: The mean values, standard deviations, and combined uncertainties showed no evidence of a significant differences between the two techniques when the head phantom ART-210 was used. (author)

  14. Quantitative analysis of multiple biokinetic models using a dynamic water phantom: A feasibility study

    Science.gov (United States)

    Chiang, Fu-Tsai; Li, Pei-Jung; Chung, Shih-Ping; Pan, Lung-Fa; Pan, Lung-Kwang

    2016-01-01

    ABSTRACT This study analyzed multiple biokinetic models using a dynamic water phantom. The phantom was custom-made with acrylic materials to model metabolic mechanisms in the human body. It had 4 spherical chambers of different sizes, connected by 8 ditches to form a complex and adjustable water loop. One infusion and drain pole connected the chambers to an auxiliary silicon-based hose, respectively. The radio-active compound solution (TC-99m-MDP labeled) formed a sealed and static water loop inside the phantom. As clean feed water was infused to replace the original solution, the system mimicked metabolic mechanisms for data acquisition. Five cases with different water loop settings were tested and analyzed, with case settings changed by controlling valve poles located in the ditches. The phantom could also be changed from model A to model B by transferring its vertical configuration. The phantom was surveyed with a clinical gamma camera to determine the time-dependent intensity of every chamber. The recorded counts per pixel in each chamber were analyzed and normalized to compare with theoretical estimations from the MATLAB program. Every preset case was represented by uniquely defined, time-dependent, simultaneous differential equations, and a corresponding MATLAB program optimized the solutions by comparing theoretical calculations and practical measurements. A dimensionless agreement (AT) index was recommended to evaluate the comparison in each case. ATs varied from 5.6 to 48.7 over the 5 cases, indicating that this work presented an acceptable feasibility study. PMID:27286096

  15. Evaluation of the water equivalence of solid phantoms using gamma ray transmission measurements

    International Nuclear Information System (INIS)

    Hill, R.F.; Brown, S.; Baldock, C.

    2008-01-01

    Gamma ray transmission measurements have been used to evaluate the water equivalence of solid phantoms. Technetium-99m was used in narrow beam geometry and the transmission of photons measured, using a gamma camera, through varying thickness of the solid phantom material and water. Measured transmission values were compared with Monte Carlo calculated transmission data using the EGSnrc Monte Carlo code to score fluence in a geometry similar to that of the measurements. The results indicate that the RMI457 Solid Water, CMNC Plastic Water and PTW RW3 solid phantoms had similar transmission values as compared to water to within ±1.5%. However, Perspex had a greater deviation in the transmission values up to ±4%. The agreement between the measured and EGSnrc calculated transmission values agreed to within ±1% over the range of phantom thickness studied. The linear attenuation coefficients at the gamma ray energy of 140.5 keV were determined from the measured and EGSnrc calculated transmission data and compared with predicted values derived from data provided by the National Institute of Standards and Technology (NIST) using the XCOM program. The coefficients derived from the measured data were up to 6% lower than those predicted by the XCOM program, while the coefficients determined from the Monte Carlo calculations were between measured and XCOM values. The results indicate that a similar process can be followed to determine the water equivalency of other solid phantoms and at other photon energies

  16. A custom made phantom for dosimetric audit and quality assurance of three-dimensional conformal radiotherapy

    International Nuclear Information System (INIS)

    Radaideh, K.M.; Matalqah, L.M.; Matalqah, L.M.; Tajuddin, A.A.; Luen, F.W.L.; Bauk, S.; Abdel Munem, E.M.E.

    2012-01-01

    The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg, Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5 %. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3 %. The phantom's preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification. (author)

  17. Development of a contrast phantom for active millimeter-wave imaging systems

    Science.gov (United States)

    Barber, Jeffrey; Weatherall, James C.; Brauer, Carolyn S.; Smith, Barry T.

    2011-06-01

    As the development of active millimeter wave imaging systems continues, it is necessary to validate materials that simulate the expected response of explosives. While physics-based models have been used to develop simulants, it is desirable to image both the explosive and simulant together in a controlled fashion in order to demonstrate success. To this end, a millimeter wave contrast phantom has been created to calibrate image grayscale while controlling the configuration of the explosive and simulant such that direct comparison of their respective returns can be performed. The physics of the phantom are described, with millimeter wave images presented to show successful development of the phantom and simulant validation at GHz frequencies.

  18. Performance of an automatic dose control system for CT. Specifications and basic phantom tests

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, H.D. [Wissenschaft und Technik fuer die Radiolgoe, Dr. HD Nagel, Buchholz (Germany); Stumpp, P.; Kahn, T.; Gosch, D. [Universitaetsklinikum Leipzig (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie

    2011-01-15

    Purpose: To assess the performance and to provide more detailed insight into the characteristics and limitations of devices for automatic dose control (ADC) in CT. Materials and Methods: A comprehensive study on DoseRight 2.0, the ADC system provided by Philips for its Brilliance CT scanners, was conducted. Phantom tests were carried out on a 64-slice scanner (Brilliance 64) using assorted quality control (QC) phantoms that allowed verification of the basic specifications. If feasible, the findings were verified by model calculations based on known specifications. Results: For all tests, the dose reductions and modulation characteristics fully met the values expected from the specifications. Adverse effects due to increased image noise were only moderate as a result of the 'adequate noise system' design that employs comparatively gentle modulation, and the additional use of adaptive filtration. Conclusion: Simple tests with QC phantoms allow evaluation of the most relevant characteristics of devices for ADC in CT. (orig.)

  19. γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

    Science.gov (United States)

    Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

    2017-11-01

    We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Materials

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2009-02-01

    Full Text Available . It is generally included as part of a structurally insulated panel (SIP) where the foam is sandwiched between external skins of steel, wood or cement. Cement composites Cement bonded composites are an important class of building materials. These products... for their stone buildings, including the Egyptians, Aztecs and Inca’s. As stone is a very dense material it requires intensive heating to become warm. Rocks were generally stacked dry but mud, and later cement, can be used as a mortar to hold the rocks...

  1. Design and manufacturing of anthropomorphic thyroid-neck phantom for use in nuclear medicine centres in Chile

    International Nuclear Information System (INIS)

    Hermosilla, A.; Diaz Londono, G.; Garcia, M.; Ruiz, F.; Andrade, P.; Perez, A.

    2014-01-01

    Anthropomorphic phantoms are used in nuclear medicine for imaging quality control, calibration of gamma spectrometry system for the study of internal contamination with radionuclides and for internal dosimetric studies. These are constructed of materials that have radiation attenuation coefficients similar to those of the different organs and tissues of the human body. The material usually used for the manufacture of phantoms is polymethyl methacrylate. Other materials used for this purpose are polyethylene, polystyrene and epoxy resin. This project presents the design and manufacture of an anthropomorphic thyroid-neck phantom that includes the cervical spine, trachea and oesophagus, using a polyester resin (ρ 1.1 g cm -3 ). Its linear and mass attenuation coefficients were experimentally determined and simulated by means of XCOM software, finding that this material reproduces the soft tissue ICRU-44 in a range of energies between 80 keV and 11 MeV, with less than a 5 % difference. (authors)

  2. New mechanism to cross the phantom divide

    International Nuclear Information System (INIS)

    Du, Yunshuang; Zhang, Hongsheng; Li, Xin-Zhou

    2011-01-01

    Recently, type Ia supernova data appear to support a dark energy whose equation of state w crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in gravity with an additional inverse power-law term of the Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. Some analytical solutions with w -1 are obtained. A minimally coupled scalar with different potentials, including quadratic, cubic, quantic, exponential and logarithmic potentials are investigated via numerical methods, respectively. All these potentials lead to the crossing behavior. We show that it is a robust result which is hardly dependent on the concrete form of the potential of the scalar. (orig.)

  3. Development of a patient-specific two-compartment anthropomorphic breast phantom

    International Nuclear Information System (INIS)

    Prionas, Nicolas D; Burkett, George W; McKenney, Sarah E; Chen, Lin; Boone, John M; Stern, Robin L

    2012-01-01

    distribution for a specific patient. The modular design of the phantom allows for studies of a single breast segment and the entire breast volume. Insertion of other devices, materials and tissues of interest into the phantom provide a robust platform for future breast imaging and dosimetry studies. (paper)

  4. Phantoms for Radiation Measurements of Mobile Phones

    DEFF Research Database (Denmark)

    Pedersen, Gert Frølund

    2001-01-01

    Measurements of radiation efficiency for a handheld phone equipped with a patch and a helical antenna operated near the human user have been performed. Both measurements include a simple head plus hand phantom and live persons are considered. The position of the hand on the phone is found...... to be the main reason for the large variation in radiation efficiency among persons. The tilt angle of the phone and the distance between the head and phone only play a minor role...

  5. Implementation of Japanese male and female tomographic phantoms to multi-particle Monte Carlo code for ionizing radiation dosimetry

    International Nuclear Information System (INIS)

    Lee, Choonsik; Nagaoka, Tomoaki; Lee, Jai-Ki

    2006-01-01

    Japanese male and female tomographic phantoms, which have been developed for radio-frequency electromagnetic-field dosimetry, were implemented into multi-particle Monte Carlo transport code to evaluate realistic dose distribution in human body exposed to radiation field. Japanese tomographic phantoms, which were developed from the whole body magnetic resonance images of Japanese average adult male and female, were processed as follows to be implemented into general purpose multi-particle Monte Carlo code, MCNPX2.5. Original array size of Japanese male and female phantoms, 320 x 160 x 866 voxels and 320 x 160 x 804 voxels, respectively, were reduced into 320 x 160 x 433 voxels and 320 x 160 x 402 voxels due to the limitation of memory use in MCNPX2.5. The 3D voxel array of the phantoms were processed by using the built-in repeated structure algorithm, where the human anatomy was described by the repeated lattice of tiny cube containing the information of material composition and organ index number. Original phantom data were converted into ASCII file, which can be directly ported into the lattice card of MCNPX2.5 input deck by using in-house code. A total of 30 material compositions obtained from International Commission on Radiation Units and Measurement (ICRU) report 46 were assigned to 54 and 55 organs and tissues in the male and female phantoms, respectively, and imported into the material card of MCNPX2.5 along with the corresponding cross section data. Illustrative calculation of absorbed doses for 26 internal organs and effective dose were performed for idealized broad parallel photon and neutron beams in anterior-posterior irradiation geometry, which is typical for workers at nuclear power plant. The results were compared with the data from other Japanese and Caucasian tomographic phantom, and International Commission on Radiological Protection (ICRP) report 74. The further investigation of the difference in organ dose and effective dose among tomographic

  6. Development of phantom periapical for control quality

    International Nuclear Information System (INIS)

    Mendes, J.M.S.; Sales Junior, E.S.; Ferreira, F.C.L.; Paschoal, C.M.M.

    2015-01-01

    This study aimed to develop a dental phantom with cysts for evaluation of periapical radiographs that was tested in private dental offices in the city of Maraba, northern Brazil. Through some tests with the object simulator (phantom) were obtained 12 periapical radiographs (one in each of the offices visited) that waking up to the standards of Ordinance No. 453 were visually evaluated by observing the physical parameters of exposure (kVp and mA), time revelation of the radiographic film, later the other radiographs were visually compared with C6 ray set as the default. Among the results, it was found that only two of the twelve rays cysts could not be viewed and, therefore, these two images were deemed unsuitable for accurate diagnosis in the 10 images the cysts could be displayed, however according the images have different qualities comparisons. In addition, it can be concluded that the performance of the phantom was highly satisfactory showing to be efficient for use in quality control testing of dental X-rays, the quality control of radiographs and continuing education of dental professionals for a price much more accessible. (authors)

  7. Patient specific 3D printed phantom for IMRT quality assurance

    International Nuclear Information System (INIS)

    Ehler, Eric D; Higgins, Patrick D; Dusenbery, Kathryn E; Barney, Brett M

    2014-01-01

    The purpose of this study was to test the feasibility of a patient specific phantom for patient specific dosimetric verification. Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. Calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was compared for a parallel-opposed head and neck field geometry to establish tissue equivalence. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom as well as traditional standard phantoms. The maximum difference in calculated dose was 1.8% for the parallel-opposed configuration. Passing rates of various dosimetric parameters were compared for the IMRT plan measurements; the 3D printed phantom results showed greater disagreement at superficial depths than other methods. A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine use. (paper)

  8. Composition of MRI phantom equivalent to human tissues

    International Nuclear Information System (INIS)

    Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Yoshida, Atsushi; Hanamoto, Katsumi; Kawasaki, Shoji; Shibuya, Koichi; Kanazawa, Susumu

    2005-01-01

    We previously developed two new MRI phantoms (called the CAG phantom and the CAGN phantom), with T1 and T2 relaxation times equivalent to those of any human tissue at 1.5 T. The conductivity of the CAGN phantom is equivalent to that of most types of human tissue in the frequency range of 1 to 130 MHz. In this paper, the relaxation times of human tissues are summarized, and the composition of the corresponding phantoms are provided in table form. The ingredients of these phantoms are carrageenan as the gelling agent, GdCl 3 as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN 3 as an antiseptic, and distilled water. The phantoms have T1 values of 202-1904 ms and T2 values of 38-423 ms when the concentrations of GdCl 3 and agarose are varied from 0-140 μmol/kg, and 0%-1.6%, respectively, and the CAGN phantom has a conductivity of 0.27-1.26 S/m when the NaCl concentration is varied from 0%-0.7%. These phantoms have sufficient strength to replicate a torso without the use of reinforcing agents, and can be cut by a knife into any shape. We anticipate the CAGN phantom to be highly useful and practical for MRI and hyperthermia-related research

  9. Reproducing 2D breast mammography images with 3D printed phantoms

    Science.gov (United States)

    Clark, Matthew; Ghammraoui, Bahaa; Badal, Andreu

    2016-03-01

    Mammography is currently the standard imaging modality used to screen women for breast abnormalities and, as a result, it is a tool of great importance for the early detection of breast cancer. Physical phantoms are commonly used as surrogates of breast tissue to evaluate some aspects of the performance of mammography systems. However, most phantoms do not reproduce the anatomic heterogeneity of real breasts. New fabrication technologies, such as 3D printing, have created the opportunity to build more complex, anatomically realistic breast phantoms that could potentially assist in the evaluation of mammography systems. The primary objective of this work is to present a simple, easily reproducible methodology to design and print 3D objects that replicate the attenuation profile observed in real 2D mammograms. The secondary objective is to evaluate the capabilities and limitations of the competing 3D printing technologies, and characterize the x-ray properties of the different materials they use. Printable phantoms can be created using the open-source code introduced in this work, which processes a raw mammography image to estimate the amount of x-ray attenuation at each pixel, and outputs a triangle mesh object that encodes the observed attenuation map. The conversion from the observed pixel gray value to a column of printed material with equivalent attenuation requires certain assumptions and knowledge of multiple imaging system parameters, such as x-ray energy spectrum, source-to-object distance, compressed breast thickness, and average breast material attenuation. A detailed description of the new software, a characterization of the printed materials using x-ray spectroscopy, and an evaluation of the realism of the sample printed phantoms are presented.

  10. The role of phantom and treatment head generated bremsstrahlung in high-energy electron beam dosimetry

    International Nuclear Information System (INIS)

    Sorcini, B.B.; Hyoedynmaa, S.; Brahme, A.

    1996-01-01

    An analytical expression has been derived for the phantom generated bremsstrahlung photons in plane-parallel monoenergetic electron beams normally incident on material of any atomic number (Be, H 2 O, Al, Cu and U). The expression is suitable for the energy range from 1 to 50 MeV and it is solely based on known scattering power and radiative and collision stopping power data for the material at the incident electron energy. The depth dose distribution due to the bremsstrahlung generated by the electrons in the phantom is derived by convolving the bremsstrahlung energy fluence produced in the phantom with a simple analytical energy deposition kernel. The kernel accounts for both electrons and photons set in motion by the bremsstrahlung photons. The energy loss by the primary electrons, the build-up of the electron fluence and the generation, attenuation and absorption of bremsstrahlung photons are all taken into account in the analytical formula. The longitudinal energy deposition kernel is derived analytically and it is consistent with both the classical biexponential relation describing the photon depth dose distribution and the exponential attenuation of the primary photons. For comparison Monte Carlo calculated energy deposition distributions using ITS3 code were used. Good agreement was found between the results with the analytical expression and the Monte Carlo calculation. For tissue equivalent materials, the maximum total energy deposition differs by less than 0.2% from Monte Carlo calculated dose distributions. The result can be used to estimate the depth dependence of phantom generated bremsstrahlung in different materials in therapeutic electron beams and the bremsstrahlung production in different electron absorbers such as scattering foils, transmission monitors and photon and electron collimators. By subtracting the phantom generated bremsstrahlung from the total bremsstrahlung background the photon contamination generated in the treatment head can be

  11. MO-B-BRD-01: Creation of 3D Printed Phantoms for Clinical Radiation Therapy

    International Nuclear Information System (INIS)

    Ehler, E.

    2015-01-01

    This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus and compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data

  12. MO-B-BRD-01: Creation of 3D Printed Phantoms for Clinical Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ehler, E. [University of Minnesota (United States)

    2015-06-15

    This session is designed so that the learning objectives are practical. The intent is that the attendee may take home an understanding of not just the technology, but also the logistical steps necessary to execute these 3D printing techniques in the clinic. Four practical 3D printing topics will be discussed: (i) Creating bolus and compensators for photon machines; (ii) tools for proton therapy; (iii) clinical applications in imaging; (iv) custom phantom design for clinic and research use. The use of 3D printers within the radiation oncology setting is proving to be a useful tool for creating patient specific bolus and compensators with the added benefit of cost savings. Creating the proper protocol is essential to ensuring that the desired effect is achieved and modeled in the treatment planning system. The critical choice of printer material (since it determines the interaction with the radiation) will be discussed. Selection of 3D printer type, design methods, verification of dose calculation, and the printing process will be detailed to give the basis for establishing your own protocol for electron and photon fields. A practical discussion of likely obstacles that may be encountered will be included. The diversity of systems and techniques in proton facilities leads to different facilities having very different requirements for beam modifying hardware and quality assurance devices. Many departments find the need to design and fabricate facility-specific equipment, making 3D printing an attractive technology. 3D printer applications in proton therapy will be discussed, including beam filters and compensators, and the design of proton therapy specific quality assurance tools. Quality control specific to 3D printing in proton therapy will be addressed. Advantages and disadvantages of different printing technology for these applications will also be discussed. 3D printing applications using high-resolution radiology-based imaging data will be presented. This data

  13. A computer-simulated liver phantom (virtual liver phantom) for multidetector computed tomography evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Funama, Yoshinori [Kumamoto University, Department of Radiological Sciences, School of Health Sciences, Kumamoto (Japan); Awai, Kazuo; Nakayama, Yoshiharu; Liu, Da; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Miyazaki, Osamu; Goto, Taiga [Hitachi Medical Corporation, Tokyo (Japan); Hori, Shinichi [Gate Tower Institute of Image Guided Therapy, Osaka (Japan)

    2006-04-15

    The purpose of study was to develop a computer-simulated liver phantom for hepatic CT studies. A computer-simulated liver phantom was mathematically constructed on a computer workstation. The computer-simulated phantom was calibrated using real CT images acquired by an actual four-detector CT. We added an inhomogeneous texture to the simulated liver by referring to CT images of chronically damaged human livers. The mean CT number of the simulated liver was 60 HU and we added numerous 5-to 10-mm structures with 60{+-}10 HU/mm. To mimic liver tumors we added nodules measuring 8, 10, and 12 mm in diameter with CT numbers of 60{+-}10, 60{+-}15, and 60{+-}20 HU. Five radiologists visually evaluated similarity of the texture of the computer-simulated liver phantom and a real human liver to confirm the appropriateness of the virtual liver images using a five-point scale. The total score was 44 in two radiologists, and 42, 41, and 39 in one radiologist each. They evaluated that the textures of virtual liver were comparable to those of human liver. Our computer-simulated liver phantom is a promising tool for the evaluation of the image quality and diagnostic performance of hepatic CT imaging. (orig.)

  14. MOSFET dosimeter depth-dose measurements in heterogeneous tissue-equivalent phantoms at diagnostic x-ray energies

    International Nuclear Information System (INIS)

    Jones, A.K.; Pazik, F.D.; Hintenlang, D.E.; Bolch, W.E.

    2005-01-01

    The objective of the present study was to explore the use of the TN-1002RD metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter for measuring tissue depth dose at diagnostic photon energies in both homogeneous and heterogeneous tissue-equivalent materials. Three cylindrical phantoms were constructed and utilized as a prelude to more complex measurements within tomographic physical phantoms of pediatric patients. Each cylindrical phantom was constructed as a stack of seven 5-cm-diameter and 1-cm-thick discs of materials radiographically representative of either soft tissue (S), bone (B), or lung tissue (L) at diagnostic photon energies. In addition to a homogeneous phantom of soft tissue (SSSSSSS), two heterogeneous phantoms were constructed: SSBBSSS and SBLLBSS. MOSFET dosimeters were then positioned at the interface of each disc, and the phantoms were then irradiated at 66 kVp and 200 mAs. Measured values of absorbed dose at depth were then compared to predicated values of point tissue dose as determined via Monte Carlo radiation transport modeling. At depths exceeding 2 cm, experimental results matched the computed values of dose with high accuracy regardless of the dosimeter orientation (epoxy bubble facing toward or away from the x-ray beam). Discrepancies were noted, however, between measured and calculated point doses near the surface of the phantom (surface to 2 cm depth) when the dosimeters were oriented with the epoxy bubble facing the x-ray beam. These discrepancies were largely eliminated when the dosimeters were placed with the flat side facing the x-ray beam. It is therefore recommended that the MOSFET dosimeters be oriented with their flat sides facing the beam when they are used at shallow depths or on the surface of either phantoms or patients

  15. Hydra phantom applicability for carrying out tests of field uniformity in gamma cameras

    International Nuclear Information System (INIS)

    Aragao Filho, Geraldo L.; Oliveira, Alex C.H.

    2014-01-01

    Nuclear Medicine is a medical modality that makes use of radioactive material 'in vivo' in humans, making them a temporary radioactive source. The radiation emitted by the patient's body is detected by a specific equipment, called a gamma camera, creates an image showing the spatial and temporal biodistribution of radioactive material administered to the patient. Therefore, it's of fundamental importance a number of specific measures to make sure that procedure be satisfactory, called quality control. To Nuclear Medicine, quality control of gamma camera has the purpose of ensuring accurate scintillographic imaging, truthful and reliable for the diagnosis, guaranteeing visibility and clarity of details of structures, and also to determine the frequency and the need for preventive maintenance of equipment. To ensure the quality control of the gamma camera it's necessary to use some simulators, called phantom, used in Nuclear Medicine to evaluate system performance, system calibration and simulation of injuries. The goal of this study was to validate a new simulator for nuclear medicine, the Hydra phantom. The phantom was initially built for construction of calibration curves used in radiotherapy planning and quality control in CT. It has similar characteristics to specific phantoms in nuclear medicine, containing inserts and water area. Those inserts are regionally sourced materials, many of them are already used in the literature and based on information about density and interaction of radiation with matter. To verify its efficiency in quality control in Nuclear Medicine, was performed a test for uniformity field, one of the main tests performed daily, so we can verify the ability of the gamma camera to reproduce a uniform distribution of the administered activity in the phantom, been analysed qualitatively, through the image, and quantitatively, through values established for Central Field Of View (CFOV) and Useful Field Of View (UFOV). Also, was evaluated their

  16. Homogeneous Canine Chest Phantom Construction: A Tool for Image Quality Optimization.

    Directory of Open Access Journals (Sweden)

    Ana Luiza Menegatti Pavan

    Full Text Available Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air. Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05 quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures.

  17. 3D printing X-Ray Quality Control Phantoms. A Low Contrast Paradigm

    Science.gov (United States)

    Kapetanakis, I.; Fountos, G.; Michail, C.; Valais, I.; Kalyvas, N.

    2017-11-01

    Current 3D printing technology products may be usable in various biomedical applications. Such an application is the creation of X-ray quality control phantoms. In this work a self-assembled 3D printer (geeetech i3) was used for the design of a simple low contrast phantom. The printing material was Polylactic Acid (PLA) (100% printing density). Low contrast scheme was achieved by creating air-holes with different diameters and thicknesses, ranging from 1mm to 9mm. The phantom was irradiated at a Philips Diagnost 93 fluoroscopic installation at 40kV-70kV with the semi-automatic mode. The images were recorded with an Agfa cr30-x CR system and assessed with ImageJ software. The best contrast value observed was approximately 33%. In low contrast detectability check it was found that the 1mm diameter hole was always visible, for thickness larger or equal to 4mm. A reason for not being able to distinguish 1mm in smaller thicknesses might be the presence of printing patterns on the final image, which increased the structure noise. In conclusion the construction of a contrast resolution phantom with a 3D printer is feasible. The quality of the final product depends upon the printer accuracy and the material characteristics.

  18. Model of optical phantoms thermal response upon irradiation with 975 nm dermatological laser

    Science.gov (United States)

    Wróbel, M. S.; Bashkatov, A. N.; Yakunin, A. N.; Avetisyan, Yu. A.; Genina, E. A.; Galla, S.; Sekowska, A.; Truchanowicz, D.; Cenian, A.; Jedrzejewska-Szczerska, M.; Tuchin, V. V.

    2018-04-01

    We have developed a numerical model describing the optical and thermal behavior of optical tissue phantoms upon laser irradiation. According to our previous studies, the phantoms can be used as substitute of real skin from the optical, as well as thermal point of view. However, the thermal parameters are not entirely similar to those of real tissues thus there is a need to develop mathematical model, describing the thermal and optical response of such materials. This will facilitate the correction factors, which would be invaluable in translation between measurements on skin phantom to real tissues, and gave a good representation of a real case application. Here, we present the model dependent on the data of our optical phantoms fabricated and measured in our previous preliminary study. The ambiguity between the modeling and the thermal measurements depend on lack of accurate knowledge of material's thermal properties and some exact parameters of the laser beam. Those parameters were varied in the simulation, to provide an overview of possible parameters' ranges and the magnitude of thermal response.

  19. Performance of an automatic dose control system for CT. Anthropomorphic phantom studies

    Energy Technology Data Exchange (ETDEWEB)

    Gosch, D.; Stumpp, P.; Kahn, T. [Universitaetsklinikum Leipzig (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie; Nagel, H.D. [Wissenschaft und Technik fuer die Radiologie, Dr. HD Nagel, Buchholz (Germany)

    2011-02-15

    Purpose: To assess the performance and to provide more detailed insight into characteristics and limitations of devices for automatic dose control (ADC) in CT. Materials and Methods: A comprehensive study on DoseRight 2.0, the ADC system provided by Philips for its Brilliance CT scanners, was conducted with assorted tests using an anthropomorphic phantom that allowed simulation of the operation of the system under almost realistic conditions. The scan protocol settings for the neck, chest and abdomen with pelvis were identical to those applied in the clinical routine. Results: Using the appropriate ADC functionalities, dose reductions equal 40 % for the neck, 20 % for the chest and 10 % for the abdomen with pelvis. Larger dose reductions can be expected for average patients, since their attenuating properties differ significantly from the anthropomorphic phantom. Adverse effects due to increased image noise were only moderate as a consequence of the 'adequate noise system' design and the complementary use of adaptive filtration. The results of specific tests also provided deeper insight into the operation of the ADC system that helps to identify the causes of suspected malfunctions and to prevent potential pitfalls. Conclusion: Tests with anthropomorphic phantoms allow verification of the characteristics of devices for ADC in CT under almost realistic conditions. However, differences in phantom shape and material composition require supplementary patient studies on representative patient groups. (orig.)

  20. Experience with the Alderson Rando phantom. [17-MeV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Somerwil, A; Kleffens, H.J. Van [Rotterdams Radio Therapeutisch Instituut (Netherlands)

    1977-04-01

    The dose delivered to the spinal cord is of particular interest in electron beam therapy of medulloblastoma. Lithium fluoride thermoluminescent dosimetry has been used in an assessment of the dose distributions from a 17 MeV electron beam in an Alderson Rando Phantom (Alderson, S.W., Lanzl, L.H., Rollins, M., and Spira, J., 1962, American J. of Roentgenology, Radium Therapy and Nuclear Medicine, vol. 87, 185). Measurements were also made on three autopsy specimens immersed in water. There were substantial differences between the two sets of results. The density of the bony part of the phantom seemed to be markedly lower than that of the water; radiographs of various parts of the phantom confirmed that large areas of low density existed. The manufacturers have stated that in order to simulate true in vivo conditions, an artificial skeleton would have to be introduced into the tissue-like material of the phantom, and that the real skeletons now used appear to be unsuitable for electron beam dosimetry. It is therefore doubtful whether this electron beam dosimetry justifies the expense associated with the insertion of these unsatisfactory skeletons into the soft tissue-equivalent material.

  1. A capillary-based perfusion phantom for simulation of brain perfusion for MRI; Ein kapillarbasiertes Phantom zur Simulation der Gehirnperfusion mit der Magnet-Resonanz-Tomografie

    Energy Technology Data Exchange (ETDEWEB)

    Maciak, A.; Kronfeld, A.; Mueller-Forell, W. [Universitaetsklinikum Mainz (Germany). Inst. fuer Neuroradiologie; Wille, C. [Fachhochschule Bingen (Germany). Inst. fuer Informatik; Kempski, O. [Universitaetsklinikum Mainz (Germany). Inst. fuer Neurochirurgische Pathophysiologie; Stoeter, P. [CEDIMAT, Santo Domingo (Dominican Republic). Inst. of Neuroradiology

    2010-10-15

    Purpose: The measurement of the CBF is a non-standardized procedure and there are no reliable gold standards. This abstract shows a capillary-based perfusion-phantom for CE-DSC-MRI. It has equivalent flow properties to those within the tissue capillary system of the human brain and allows the validation of the Siemens Perfusion (MR) software. Materials and Methods: The perfusion phantom consists of a dialyzer for the simulation of the capillary system, a feeding tube for simulation of the AIF and a pulsatile pump for simulation of the heart. Using this perfusion phantom, the exact determination of the gold standard CBF due to the well-known geometry of the phantom is easy. It was validated based on different perfusion measurements. These measurements were investigated with standard software (Siemens Perfusion MR). The software determined the CBF within the capillary system. Based on this CBF, a comparison to the gold standard was made with several different flow speeds. After AIF selection, a total of 726 CBF data points were automatically extracted by the software. Results: This results in a comparison of the gold standard CBF to these 726 CBF values. Therefore, a reproducible and reliable deviation estimation between gold standard CBF and measured CBF using the software was computed. It can be shown that the deviation between gold standard and software-based evaluation ranges between 1 and 31 %. Conclusion: There is no significance for any correlation between flow speed and amount of deviation. The mean measured CBF is 11.4 % higher than the gold standard CBF (p-value < 0.001). Using this kind of perfusion-phantom, the validation of different software systems allows reliable conclusions about their quality. (orig.)

  2. Porous silicon phantoms for high-resolution scintillation imaging

    Energy Technology Data Exchange (ETDEWEB)

    Di Francia, G. [Portici Research Centre, ENEA, Via Vecchio Macello, 80055 Portici, Naples (Italy); Scafe, R. [Casaccia Research Centre, ENEA, 00060 S.Maria di Galeria, Rome (Italy)]. E-mail: scafe@casaccia.enea.it; De Vincentis, G. [Department of Radiological Sciences, University of Rome ' La Sapienza' , V.le Regina Elena, 324, 00161 Rome (Italy); La Ferrara, V. [Portici Research Centre, ENEA, Via Vecchio Macello, 80055 Portici, Naples (Italy); Iurlaro, G. [Casaccia Research Centre, ENEA, 00060 S.Maria di Galeria, Rome (Italy); Nasti, I. [Portici Research Centre, ENEA, Via Vecchio Macello, 80055 Portici, Naples (Italy); Montani, L. [Casaccia Research Centre, ENEA, 00060 S.Maria di Galeria, Rome (Italy); Pellegrini, R. [Department of Experimental Medicine, University of Rome ' La Sapienza' , V.le Regina Elena, 324, 00161 Rome (Italy); Betti, M. [Department of Experimental Medicine, University of Rome ' La Sapienza' , V.le Regina Elena, 324, 00161 Rome (Italy); Martucciello, N. [Portici Research Centre, ENEA, Via Vecchio Macello, 80055 Portici, Naples (Italy); Pani, R. [Department of Experimental Medicine, University of Rome ' La Sapienza' , V.le Regina Elena, 324, 00161 Rome (Italy)

    2006-12-20

    High resolution radionuclide imaging requires phantoms with precise geometries and known activities using either Anger cameras equipped with pinhole collimators or dedicated small animal devices. Porous silicon samples, having areas of different shape and size, can be made and loaded with a radioactive material, obtaining: (a) precise radio-emitting figures corresponding to the porous areas geometry (b) a radioactivity of each figure depending on the pore's specifications, and (c) the same emission energy to be used in true exams. To this aim a sample with porous circular areas has been made and loaded with a {sup 99m}TcO{sub 4} {sup -} solution. Imaging has been obtained using both general purpose and pinhole collimators. This first sample shows some defects that are analyzed and discussed.

  3. An evaluation of three simple phantoms used in quality assurance of automatic exposure control

    International Nuclear Information System (INIS)

    Reynolds, S.E.; Rofe, S.

    2000-01-01

    Full text: Different attenuators are used to assess the performance of x-ray systems with automatic exposure control (AEC). Three attenuators, copper, water and hardboard, were compared in this assessment. The Health Physics Service (HPS), which is part of the Department of Medical Physics and Bioengineering at Christchurch Hospital, New Zealand, has chosen to use hardboard as its patient equivalent phantom when testing x-ray equipment simply because it is generally easier to handle compared to water phantoms. Tests were conducted on the hardboard phantom in order to evaluate its effect on radiation in terms of attenuation equivalence, production of scatter and sensitivity to different kilovoltages compared to water or copper. Entrance and exit dose comparison tests were conducted using the AEC on a Philips Optimus 50 x-ray machine. A Keithley Triad Field Service Kit Model 10100A was used to record doses. The first set of tests were designed to ascertain the thickness of water and copper required to produce a similar mAs to the particular thickness of hardboard being examined. The tests were repeated with a film in a cassette which was placed in the bucky tray. Film optical densities were then measured. The hardboard phantom shows a very similar response to radiation as water and hence the human body and is therefore a suitable material for use in the construction of phantoms. Copper produces a very different radiation spectrum and its scattering effects are quite different to water or hardboard. For these reasons we consider copper to be unsuitable for use as a phantom when programming AECs. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine

  4. Contrast reference values in panoramic radiographic images using an arch-form phantom stand

    International Nuclear Information System (INIS)

    Shin, Jae Myung; Lee, Che Na; Kim, Jo Eun; Huh, Kyung Hoe; Yi, Won Jin; Heo, Min Suk; Choi, Soon Chul; Lee, Sam Sun

    2016-01-01

    The purpose of this study was to investigate appropriate contrast reference values (CRVs) by comparing the contrast in phantom and clinical images. Phantom contrast was measured using two methods: (1) counting the number of visible pits of different depths in an aluminum plate, and (2) obtaining the contrast-to-noise ratio (CNR) for 5 tissue-equivalent materials (porcelain, aluminum, polytetrafluoroethylene [PTFE], polyoxymethylene [POM], and polymethylmethacrylate [PMMA]). Four panoramic radiographs of the contrast phantom, embedded in the 4 different regions of the arch-form stand, and 1 real skull phantom image were obtained, post-processed, and compared. The clinical image quality evaluation chart was used to obtain the cut-off values of the phantom CRV corresponding to the criterion of being adequate for diagnosis. The CRVs were obtained using 4 aluminum pits in the incisor and premolar region, 5 aluminum pits in the molar region, and 2 aluminum pits in the temporomandibular joint (TMJ) region. The CRVs obtained based on the CNR measured in the anterior region were: porcelain, 13.95; aluminum, 9.68; PTFE, 6.71; and POM, 1.79. The corresponding values in the premolar region were: porcelain, 14.22; aluminum, 8.82; PTFE, 5.95; and POM, 2.30. In the molar region, the following values were obtained: porcelain, 7.40; aluminum, 3.68; PTFE, 1.27; and POM, - 0.18. The CRVs for the TMJ region were: porcelain, 3.60; aluminum, 2.04; PTFE, 0.48; and POM, - 0.43. CRVs were determined for each part of the jaw using the CNR value and the number of pits observed in phantom images

  5. Establishing High-Quality Prostate Brachytherapy Using a Phantom Simulator Training Program

    Energy Technology Data Exchange (ETDEWEB)

    Thaker, Nikhil G. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Kudchadker, Rajat J. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Swanson, David A. [Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Albert, Jeffrey M. [Department of Radiation Oncology, Banner Health, Loveland/Greeley, Colorado (United States); Mahmood, Usama; Pugh, Thomas J.; Boehling, Nicholas S. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Bruno, Teresa L. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Prestidge, Bradley R. [Department of Radiation Oncology, Bon Secours Health System, Norfolk, Virginia (United States); Crook, Juanita M. [Department of Radiation Oncology, Cancer Center for the Southern Interior, Kelowna, British Columbia (Canada); Cox, Brett W.; Potters, Louis [Department of Radiation Medicine, North Shore-LIJ Health System, New Hyde Park, New York (United States); Moran, Brian J. [Chicago Prostate Center, Westmont, Illinois (United States); Keyes, Mira [Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver Center, Vancouver, British Columbia (Canada); Kuban, Deborah A. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Frank, Steven J., E-mail: sjfrank@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2014-11-01

    Purpose: To design and implement a unique training program that uses a phantom-based simulator to teach the process of prostate brachytherapy (PB) quality assurance and improve the quality of education. Methods and Materials: Trainees in our simulator program were practicing radiation oncologists, radiation oncology residents, and fellows of the American Brachytherapy Society. The program emphasized 6 core areas of quality assurance: patient selection, simulation, treatment planning, implant technique, treatment evaluation, and outcome assessment. Using the Iodine 125 ({sup 125}I) preoperative treatment planning technique, trainees implanted their ultrasound phantoms with dummy seeds (ie, seeds with no activity). Pre- and postimplant dosimetric parameters were compared and correlated using regression analysis. Results: Thirty-one trainees successfully completed the simulator program during the period under study. The mean phantom prostate size, number of seeds used, and total activity were generally consistent between trainees. All trainees met the V100 >95% objective both before and after implantation. Regardless of the initial volume of the prostate phantom, trainees' ability to cover the target volume with at least 100% of the dose (V100) was not compromised (R=0.99 pre- and postimplant). However, the V150 had lower concordance (R=0.37) and may better reflect heterogeneity control of the implant process. Conclusions: Analysis of implants from this phantom-based simulator shows a high degree of consistency between trainees and uniformly high-quality implants with respect to parameters used in clinical practice. This training program provides a valuable educational opportunity that improves the quality of PB training and likely accelerates the learning curve inherent in PB. Prostate phantom implantation can be a valuable first step in the acquisition of the required skills to safely perform PB.

  6. Establishing High-Quality Prostate Brachytherapy Using a Phantom Simulator Training Program

    International Nuclear Information System (INIS)

    Thaker, Nikhil G.; Kudchadker, Rajat J.; Swanson, David A.; Albert, Jeffrey M.; Mahmood, Usama; Pugh, Thomas J.; Boehling, Nicholas S.; Bruno, Teresa L.; Prestidge, Bradley R.; Crook, Juanita M.; Cox, Brett W.; Potters, Louis; Moran, Brian J.; Keyes, Mira; Kuban, Deborah A.; Frank, Steven J.

    2014-01-01

    Purpose: To design and implement a unique training program that uses a phantom-based simulator to teach the process of prostate brachytherapy (PB) quality assurance and improve the quality of education. Methods and Materials: Trainees in our simulator program were practicing radiation oncologists, radiation oncology residents, and fellows of the American Brachytherapy Society. The program emphasized 6 core areas of quality assurance: patient selection, simulation, treatment planning, implant technique, treatment evaluation, and outcome assessment. Using the Iodine 125 ( 125 I) preoperative treatment planning technique, trainees implanted their ultrasound phantoms with dummy seeds (ie, seeds with no activity). Pre- and postimplant dosimetric parameters were compared and correlated using regression analysis. Results: Thirty-one trainees successfully completed the simulator program during the period under study. The mean phantom prostate size, number of seeds used, and total activity were generally consistent between trainees. All trainees met the V100 >95% objective both before and after implantation. Regardless of the initial volume of the prostate phantom, trainees' ability to cover the target volume with at least 100% of the dose (V100) was not compromised (R=0.99 pre- and postimplant). However, the V150 had lower concordance (R=0.37) and may better reflect heterogeneity control of the implant process. Conclusions: Analysis of implants from this phantom-based simulator shows a high degree of consistency between trainees and uniformly high-quality implants with respect to parameters used in clinical practice. This training program provides a valuable educational opportunity that improves the quality of PB training and likely accelerates the learning curve inherent in PB. Prostate phantom implantation can be a valuable first step in the acquisition of the required skills to safely perform PB

  7. Evaluation of the distribution of absorbed dose in child phantoms exposed to diagnostic medical x rays

    International Nuclear Information System (INIS)

    Chen, W.L.

    1977-01-01

    The purpose of the study was to determine, by theoretical calculation and experimental measurement, the absorbed dose distributions in two heterogeneous phantoms representing one-year- and five-year-old children from typical radiographic examinations for those ages. Theoretical work included the modification of an existing internal dose code which used Monte Carlo methods to determine doses within the Snyder-Fisher mathematical phantom. A Ge(Li) detector and a pinhole collimator were used to measure x-ray spectra which served as input (i.e., the source routine) to the modified Monte Carlo codes which were used to calculate organ doses in children. Experimental work included the fabrication of child phantoms to match the existing mathematical models. These phantoms were constructed of molded lucite shells filled with differing materials to simulate lung, skeletal, and soft-tissue regions. The skeleton regions of phantoms offered the opportunity to perform meaningful measurements of absorbed dose to bone marrow and bone. Thirteen to fourteen sites in various bones of the skeleton were chosen for placement of TLDs. These sites represented important regions in which active bone marrow is located. Sixteen typical radiographic examinations were performed representing common pediatric diagnostic procedures. The calculated and measured tissue-air values were compared for a number of organs. For most organs, the results of the calculated absorbed doses agreed with the measured absorbed doses within twice the coefficient of variation of the calculated value. The absorbed dose to specific organs for several selected radiological examinations are given for one-year-old, five-year-old, and adult phantoms. For selected radiological exposures, the risk factors of leukemia, thyroid cancer, and genetic death are estimated for one-year- and five-year-old children

  8. Multimodal, 3D pathology-mimicking bladder phantom for evaluation of cystoscopic technologies (Conference Presentation)

    Science.gov (United States)

    Smith, Gennifer T.; Lurie, Kristen L.; Zlatev, Dimitar V.; Liao, Joseph C.; Ellerbee, Audrey K.

    2016-02-01

    Optical coherence tomography (OCT) and blue light cystoscopy (BLC) have shown significant potential as complementary technologies to traditional white light cystoscopy (WLC) for early bladder cancer detection. Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing new technology designs, the diagnostic potential of systems, and novel image processing algorithms prior to validation in real tissue. Importantly, the phantom should mimic features of healthy and diseased tissue as they appear under WLC, BLC, and OCT, which are sensitive to tissue color and structure, fluorescent contrast, and optical scattering of subsurface layers, respectively. We present a phantom posing the hollow shape of the bladder and fabricated using a combination of 3D-printing and spray-coating with Dragon Skin (DS) (Smooth-On Inc.), a highly elastic polymer to mimic the layered structure of the bladder. Optical scattering of DS was tuned by addition of titanium dioxide, resulting in scattering coefficients sufficient to cover the human bladder range (0.49 to 2.0 mm^-1). Mucosal vasculature and tissue coloration were mimicked with elastic cord and red dye, respectively. Urethral access was provided through a small hole excised from the base of the phantom. Inserted features of bladder pathology included altered tissue color (WLC), fluorescence emission (BLC), and variations in layered structure (OCT). The phantom surface and underlying material were assessed on the basis of elasticity, optical scattering, layer thicknesses, and qualitative image appearance. WLC, BLC, and OCT images of normal and cancerous features in the phantom qualitatively matched corresponding images from human bladders.

  9. Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Ken, E-mail: k-ueda@radiol.med.osaka-u.ac.jp [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Yanagawa, Masahiro [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Ueguchi, Takashi [Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan); Satoh, Yukihisa; Kawai, Misa; Gyobu, Tomoko; Sumikawa, Hiromitsu; Honda, Osamu; Tomiyama, Noriyuki [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871 (Japan)

    2014-06-15

    Purpose: To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images. Materials and methods: A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured. Results: The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test). Conclusions: Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions.

  10. Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

    International Nuclear Information System (INIS)

    Ueda, Ken; Yanagawa, Masahiro; Ueguchi, Takashi; Satoh, Yukihisa; Kawai, Misa; Gyobu, Tomoko; Sumikawa, Hiromitsu; Honda, Osamu; Tomiyama, Noriyuki

    2014-01-01

    Purpose: To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images. Materials and methods: A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured. Results: The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test). Conclusions: Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions

  11. Contrast reference values in panoramic radiographic images using an arch-form phantom stand

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae Myung [Dept. of Oral and Maxillofacial Surgery, Ilsan Paik Hospital, Inje University College of Medicine, Goyang (Korea, Republic of); Lee, Che Na; Kim, Jo Eun; Huh, Kyung Hoe; Yi, Won Jin; Heo, Min Suk; Choi, Soon Chul; Lee, Sam Sun [Dept. of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    2016-09-15

    The purpose of this study was to investigate appropriate contrast reference values (CRVs) by comparing the contrast in phantom and clinical images. Phantom contrast was measured using two methods: (1) counting the number of visible pits of different depths in an aluminum plate, and (2) obtaining the contrast-to-noise ratio (CNR) for 5 tissue-equivalent materials (porcelain, aluminum, polytetrafluoroethylene [PTFE], polyoxymethylene [POM], and polymethylmethacrylate [PMMA]). Four panoramic radiographs of the contrast phantom, embedded in the 4 different regions of the arch-form stand, and 1 real skull phantom image were obtained, post-processed, and compared. The clinical image quality evaluation chart was used to obtain the cut-off values of the phantom CRV corresponding to the criterion of being adequate for diagnosis. The CRVs were obtained using 4 aluminum pits in the incisor and premolar region, 5 aluminum pits in the molar region, and 2 aluminum pits in the temporomandibular joint (TMJ) region. The CRVs obtained based on the CNR measured in the anterior region were: porcelain, 13.95; aluminum, 9.68; PTFE, 6.71; and POM, 1.79. The corresponding values in the premolar region were: porcelain, 14.22; aluminum, 8.82; PTFE, 5.95; and POM, 2.30. In the molar region, the following values were obtained: porcelain, 7.40; aluminum, 3.68; PTFE, 1.27; and POM, - 0.18. The CRVs for the TMJ region were: porcelain, 3.60; aluminum, 2.04; PTFE, 0.48; and POM, - 0.43. CRVs were determined for each part of the jaw using the CNR value and the number of pits observed in phantom images.

  12. Development of an organ-specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols.

    Science.gov (United States)

    Abdullah, Kamarul A; McEntee, Mark F; Reed, Warren; Kench, Peter L

    2018-04-30

    An ideal organ-specific insert phantom should be able to simulate the anatomical features with appropriate appearances in the resultant computed tomography (CT) images. This study investigated a 3D printing technology to develop a novel and cost-effective cardiac insert phantom derived from volumetric CT image datasets of anthropomorphic chest phantom. Cardiac insert volumes were segmented from CT image datasets, derived from an anthropomorphic chest phantom of Lungman N-01 (Kyoto Kagaku, Japan). These segmented datasets were converted to a virtual 3D-isosurface of heart-shaped shell, while two other removable inserts were included using computer-aided design (CAD) software program. This newly designed cardiac insert phantom was later printed by using a fused deposition modelling (FDM) process via a Creatbot DM Plus 3D printer. Then, several selected filling materials, such as contrast media, oil, water and jelly, were loaded into designated spaces in the 3D-printed phantom. The 3D-printed cardiac insert phantom was positioned within the anthropomorphic chest phantom and 30 repeated CT acquisitions performed using a multi-detector scanner at 120-kVp tube potential. Attenuation (Hounsfield Unit, HU) values were measured and compared to the image datasets of real-patient and Catphan ® 500 phantom. The output of the 3D-printed cardiac insert phantom was a solid acrylic plastic material, which was strong, light in weight and cost-effective. HU values of the filling materials were comparable to the image datasets of real-patient and Catphan ® 500 phantom. A novel and cost-effective cardiac insert phantom for anthropomorphic chest phantom was developed using volumetric CT image datasets with a 3D printer. Hence, this suggested the printing methodology could be applied to generate other phantoms for CT imaging studies. © 2018 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical

  13. Experimental phantom verification studies for simulations of light interactions with skin: liquid phantoms

    CSIR Research Space (South Africa)

    Karsten, A

    2010-09-01

    Full Text Available stream_source_info Karsten_2010_P.pdf.txt stream_content_type text/plain stream_size 5080 Content-Encoding UTF-8 stream_name Karsten_2010_P.pdf.txt Content-Type text/plain; charset=UTF-8 Experimental phantom verification... studies for simulations of light interactions with skin: Solid Phantoms Aletta E Karsten, A Singh Presented by: J E Smit National Laser Center CSIR South Africa akarsten@csir.co.za Slide 2 © CSIR 2009 www.csir.co.za Where...

  14. Mathematical human phantoms and their application to radiation protection

    International Nuclear Information System (INIS)

    Yamaguchi, Yasuhiro

    1998-01-01

    This review described the characteristics of mathematical phantoms, their history over 30 years and their application. Mathematical phantoms are classified into two models of formula and voxel types. In the former, human body and organs are described by 2- and/or 3-D mathematical formula and can be seen as a combination of solid bodies like spheres, cubes and ovals. The phantom is composed from three tissue components (bone, lung and soft tissue) and made on data on Reference Man in ICRP Publ. 23. The latter voxel (volume pixel) phantom consists from a number of small cubes based on CT and MRI images of a certain man. For instance, the phantom CHILD, 1.54 x 1.54 x 8.00 mm 3 in size, is based on a 7-year old child, which consisting from about one million voxels. The mathematical phantom was first made in Oak Ridge National Laboratory in the middle of the nineteen-sixties, which have undergone various improvements to reach MIRD-5 phantom. Thereafter, many similitude phantoms have been made as a variation of MIRD-5, depending on age and sex (e.g., ADAM and EVA). Voxel phantom was made in the middle of nineteen-eighties and have undergone improvements which are continued even currently in Japan, U.S. etc. The mathematical phantoms are used for calculation of radiation transport program by Monte Carlo method in the field of radiation protection. Also in the field of medicine, the phantom is used for calculation of internal and external exposure doses, of correction constants of externally measuring instruments, of doses for neutron capture therapy and of A-bomb exposure doses in Hiroshima and Nagasaki for reevaluation. Recently, the development of phantom is in the current from formula phantom to voxel one due to the purpose of precision and standardization. (K.H.)

  15. SU-E-J-49: Design and Fabrication of Custom 3D Printed Phantoms for Radiation Therapy Research and Quality Assurance

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, C; Xing, L [Stanford University, Stanford, CA (United States)

    2015-06-15

    Purpose The rapid proliferation of affordable 3D printing techniques has enabled the custom fabrication of items ranging from paper weights to medical implants. This study investigates the feasibility of utilizing the technology for developing novel phantoms for use in radiation therapy quality assurance (QA) procedures. Methods A phantom for measuring the geometric parameters of linear accelerator (LINAC) on-board imaging (OBI) systems was designed using SolidWorks. The design was transferred to a 3D printer and fabricated using a fused deposition modeling (FDM) technique. Fiducials were embedded in the phantom by placing 1.6 mm diameter steel balls in predefined holes and securing them with silicone. Several MV and kV images of the phantom were collected and the visibility and geometric accuracy were evaluated. A second phantom, for use in the experimental evaluation of a high dose rate (HDR) brachytherapy dosimeter, was designed to secure several applicator needles in water. The applicator was fabricated in the same 3D printer and used for experiments. Results The general accuracy of printed parts was determined to be 0.1 mm. The cost of materials for the imaging and QA phantoms were $22 and $5 respectively. Both the plastic structure and fiducial markers of the imaging phantom were visible in MV and kV images. Fiducial marker locations were determined to be within 1mm of desired locations, with the discrepancy being attributed to the fiducial attachment process. The HDR phantom secured the applicators within 0.5 mm of the desired locations. Conclusion 3D printing offers an inexpensive method for fabricating custom phantoms for use in radiation therapy quality assurance. While the geometric accuracy of such parts is limited compared to more expensive methods, the phantoms are still highly functional and provide a unique opportunity for rapid fabrication of custom phantoms for use in radiation therapy QA and research.

  16. SU-E-J-49: Design and Fabrication of Custom 3D Printed Phantoms for Radiation Therapy Research and Quality Assurance

    International Nuclear Information System (INIS)

    Jenkins, C; Xing, L

    2015-01-01

    Purpose The rapid proliferation of affordable 3D printing techniques has enabled the custom fabrication of items ranging from paper weights to medical implants. This study investigates the feasibility of utilizing the technology for developing novel phantoms for use in radiation therapy quality assurance (QA) procedures. Methods A phantom for measuring the geometric parameters of linear accelerator (LINAC) on-board imaging (OBI) systems was designed using SolidWorks. The design was transferred to a 3D printer and fabricated using a fused deposition modeling (FDM) technique. Fiducials were embedded in the phantom by placing 1.6 mm diameter steel balls in predefined holes and securing them with silicone. Several MV and kV images of the phantom were collected and the visibility and geometric accuracy were evaluated. A second phantom, for use in the experimental evaluation of a high dose rate (HDR) brachytherapy dosimeter, was designed to secure several applicator needles in water. The applicator was fabricated in the same 3D printer and used for experiments. Results The general accuracy of printed parts was determined to be 0.1 mm. The cost of materials for the imaging and QA phantoms were $22 and $5 respectively. Both the plastic structure and fiducial markers of the imaging phantom were visible in MV and kV images. Fiducial marker locations were determined to be within 1mm of desired locations, with the discrepancy being attributed to the fiducial attachment process. The HDR phantom secured the applicators within 0.5 mm of the desired locations. Conclusion 3D printing offers an inexpensive method for fabricating custom phantoms for use in radiation therapy quality assurance. While the geometric accuracy of such parts is limited compared to more expensive methods, the phantoms are still highly functional and provide a unique opportunity for rapid fabrication of custom phantoms for use in radiation therapy QA and research

  17. Phantom models for neutron capture therapy

    International Nuclear Information System (INIS)

    Storr, G.J.

    1990-08-01

    The development of a two-dimensional phantom model using the neutron and photon transport code DOT-IV is detailed. The effects of varying basic parameters such as aperture width, neutron source energy and tissue composition have been studied. One important conclusion from the study is that narrow beam apertures will give little or no advantage for tumour dose over tissue dose even in the 'ideal beam' range of 2-7 keV. The model may be used for future filter and beam studies with confidence. 10 refs., 7 tabs., 13 figs

  18. Getting started with PhantomJS

    CERN Document Server

    Beltran, Aries

    2013-01-01

    The book will follow aA standard tutorial approach, and will beas a complete guide detailing the major aspects of PhantomJS with particular focus on Website website Testingtesting.This book is written forIf you are a JavaScript developers who are is interested in developing applications that interact with various web services, and doing that using a headless browser, then this book is ideal for you. This book iswill also be good for you if you are planning to create a headless browser testing for your web application. Basic understanding of JavaScript is assumed.

  19. Dynamics of coupled phantom and tachyon fields

    Energy Technology Data Exchange (ETDEWEB)

    Shahalam, M. [Zhejiang University of Technology, Institute for Advanced Physics and Mathematics, Hangzhou (China); Pathak, S.D.; Li, Shiyuan [Shandong University, School of Physics, Jinan (China); Myrzakulov, R. [Eurasian National University, Department of General and Theoretical Physics, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan); Wang, Anzhong [Zhejiang University of Technology, Institute for Advanced Physics and Mathematics, Hangzhou (China); Baylor University, Department of Physics, GCAP-CASPER, Waco, TX (United States)

    2017-10-15

    In this paper, we apply the dynamical analysis to a coupled phantom field with scaling potential taking particular forms of the coupling (linear and combination of linear), and present phase space analysis. We investigate if there exists a late time accelerated scaling attractor that has the ratio of dark energy and dark matter densities of the order one. We observe that the scrutinized couplings cannot alleviate the coincidence problem, however, they acquire stable late time accelerated solutions. We also discuss a coupled tachyon field with inverse square potential assuming linear coupling. (orig.)

  20. Digital luminescence radiography using a chest phantom

    International Nuclear Information System (INIS)

    Lyttkens, K.; Kehler, M.; Andersson, B.; Carlsen, S.; Ebbesen, A.; Hochbergs, P.; Stroembaeck, A.

    1993-01-01

    With the introduction of picture and archiving communicating systems an alternative image display for the wards might be a personal computer (PC). The intention with this study was to evaluate the diagnostic image quality of the monitor of a PC compared to that of a workstation. Eighty-five digital radiographs of a chest phantom with simulated tumors in the mediastinum and right lung were saved on optical discs. The examinations were reviewed by 4 radiologists on a monitor at a workstation and at a PC, and receiver operating characteristic (ROC) curves were constructed. No significant difference was found between performance of the PC and the workstation. (orig.)

  1. Dynamics of coupled phantom and tachyon fields

    International Nuclear Information System (INIS)

    Shahalam, M.; Pathak, S.D.; Li, Shiyuan; Myrzakulov, R.; Wang, Anzhong

    2017-01-01

    In this paper, we apply the dynamical analysis to a coupled phantom field with scaling potential taking particular forms of the coupling (linear and combination of linear), and present phase space analysis. We investigate if there exists a late time accelerated scaling attractor that has the ratio of dark energy and dark matter densities of the order one. We observe that the scrutinized couplings cannot alleviate the coincidence problem, however, they acquire stable late time accelerated solutions. We also discuss a coupled tachyon field with inverse square potential assuming linear coupling. (orig.)

  2. Can fruits and vegetables be used as substitute phantoms for normal human brain tissues in magnetic resonance imaging?

    International Nuclear Information System (INIS)

    Teramoto, Daisuke; Ushioda, Yuichi; Sasaki, Ayaka; Sakurai Yuki; Nagahama, Hiroshi; Nakamura, Manami; Sugimori, Hiroyuki; Sakata, Motomichi

    2013-01-01

    Various custom-made phantoms designed to optimize magnetic resonance imaging (MRI) sequences have been created and subsequently reported in Japanese Society of Radiological Technology (JSRT). However, custom-made phantoms that correctly match the T 1 -value and T 2 -values of human brain tissue (gray matter and white matter) cannot be made easily or quickly. The aim of this project was to search for alternative materials, such as fruits and vegetables, for optimizing MRI sequences. The following eight fruits and vegetables were investigated: apple, tomato, melon, apple mango (Mangifera indica), banana, avocado, peach, and eggplant. Their potential was studied for use in modeling phantoms of normal human brain tissues. MRI (T 1 - and T 2 -weighted sequences) was performed on the human brain and the fruits and vegetables using various concentrations of contrast medium (gadolinium) in the same size tubes as the custom-made phantom. The authors compared the signal intensity (SI) in human brain tissue (gray matter and white matter) with that of the fruits and the custom-made phantom. The T 1 and T 2 values were measured for banana tissue and compared with those for human brain tissue in the literature. Our results indicated that banana tissue is similar to human brain tissue (both gray matter and white matter). Banana tissue can thus be employed as an alternative phantom for the human brain for the purpose of MRI. (author)

  3. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

    International Nuclear Information System (INIS)

    Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen; Jaekel, Oliver

    2015-01-01

    With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

  4. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Jaekel, Oliver [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Heidelberg University Hospital (Germany). Dept. of Radiation Oncology; Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg (Germany)

    2015-07-01

    With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

  5. An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy.

    Science.gov (United States)

    Gallas, Raya R; Hünemohr, Nora; Runz, Armin; Niebuhr, Nina I; Jäkel, Oliver; Greilich, Steffen

    2015-12-01

    With the increasing complexity of external beam therapy "end-to-end" tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification. Copyright © 2015. Published by Elsevier GmbH.

  6. TU-H-CAMPUS-IeP2-05: Breast and Soft Tissue-Equivalent 3D Printed Phantoms for Imaging and Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hintenlang, D; Terracino, B [University Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: The study has the goal to demonstrate that breast and soft tissue-equivalent phantoms for dosimetry applications in the diagnostic energy range can be fabricated using common 3D printing methods. Methods: 3D printing provides the opportunity to rapidly prototype uniquely designed objects from a variety of materials. Common 3D printers are usually limited to printing objects based on thermoplastic materials such as PLA, or ABS. The most commonly available plastic is PLA, which has a density significantly greater than soft tissue. We utilized a popular 3D printer to demonstrate that tissue specific phantom materials can be generated through the careful selection of 3D printing parameters. A series of stepwedges were designed and printed using a Makerbot Replicator2 3D printing system. The print file provides custom adjustment of the infill density, orientation and position of the object on the printer stage, selection of infill patterns, and other control parameters. The x-ray attenuation and uniformity of fabricated phantoms were evaluated and compared to common tissue-equivalent phantom materials, acrylic and BR12. X-ray exposure measurements were made using narrow beam geometry on a clinical mammography unit at 28 kVp on the series of phantoms. The 3D printed phantoms were imaged at 28 kVp to visualize the internal structure and uniformity in different planes of the phantoms. Results: By utilizing specific in-fill density and patterns we are able to produce a phantom closely matching the attenuation characteristics of BR12 at 28 kVp. The in-fill patterns used are heterogeneous, so a judicious selection of fill pattern and the orientation of the fill pattern must be made in order to obtain homogenous attenuation along the intended direction of beam propagation. Conclusions: By careful manipulation of the printing parameters, breast and soft tissue-equivalent phantoms appropriate for use at imaging energies can be fabricated using 3D printing techniques.

  7. TU-H-CAMPUS-IeP2-05: Breast and Soft Tissue-Equivalent 3D Printed Phantoms for Imaging and Dosimetry

    International Nuclear Information System (INIS)

    Hintenlang, D; Terracino, B

    2016-01-01

    Purpose: The study has the goal to demonstrate that breast and soft tissue-equivalent phantoms for dosimetry applications in the diagnostic energy range can be fabricated using common 3D printing methods. Methods: 3D printing provides the opportunity to rapidly prototype uniquely designed objects from a variety of materials. Common 3D printers are usually limited to printing objects based on thermoplastic materials such as PLA, or ABS. The most commonly available plastic is PLA, which has a density significantly greater than soft tissue. We utilized a popular 3D printer to demonstrate that tissue specific phantom materials can be generated through the careful selection of 3D printing parameters. A series of stepwedges were designed and printed using a Makerbot Replicator2 3D printing system. The print file provides custom adjustment of the infill density, orientation and position of the object on the printer stage, selection of infill patterns, and other control parameters. The x-ray attenuation and uniformity of fabricated phantoms were evaluated and compared to common tissue-equivalent phantom materials, acrylic and BR12. X-ray exposure measurements were made using narrow beam geometry on a clinical mammography unit at 28 kVp on the series of phantoms. The 3D printed phantoms were imaged at 28 kVp to visualize the internal structure and uniformity in different planes of the phantoms. Results: By utilizing specific in-fill density and patterns we are able to produce a phantom closely matching the attenuation characteristics of BR12 at 28 kVp. The in-fill patterns used are heterogeneous, so a judicious selection of fill pattern and the orientation of the fill pattern must be made in order to obtain homogenous attenuation along the intended direction of beam propagation. Conclusions: By careful manipulation of the printing parameters, breast and soft tissue-equivalent phantoms appropriate for use at imaging energies can be fabricated using 3D printing techniques.

  8. Experimental 16-row CT evaluation of in-stent restenosis using new stationary and moving cardiac stent phantoms: experimental examination

    International Nuclear Information System (INIS)

    Yamamura, J.; Adam, G.; Begemann, P.G.; Stevendaal, U. van; Grass, M.; Koester, R.

    2006-01-01

    Purpose: The aim of this study was to evaluate in-stent restenosis using a newly developed stationary and moving cardiac stent phantom with three built-in artificial stenoses and a 16-row MDCT. Materials and Methods: A newly developed coronary stent phantom with three artificial stenoses - low (approx. 30%), medium (approx. 50%) and high (approx. 70%) - was attached to a moving heart phantom and used to evaluate the ability of 16-row MDCT to visualize in-stent restenosis. High resolution scans (16 x 0.75 mm, 250 mm FOV) were made to identify the baseline for image quality. The non-moving phantom was scanned (16 x 0.75 mm, routine cardiac scan protocol) first without and then with implementation of an ECG signal at various simulated heart rates (HR 40 to 120 bpm) and pitches (0.15 to 0.3). The moving cardiac phantom was scanned at the same simulated heart rates but at a pitch of 0.15. Images were reconstructed at every 10% of the RR interval using a multi-cycle real cone-beam reconstruction algorithm. Multi-planar reformations (MPR) were made for the image evaluation. The image quality was assessed using a three-point scale, and stent patency and stenoses detection were evaluated using a four-point scale. To evaluate the image quality and to grade the stent stenoses, the median values were calculated while considering the reconstruction interval. Results: The image quality for the static phantom was adequate in 97% of the measurements. In this phantom, every stenosis was detected independent of the pitch and heart rate used. The dynamic stent phantom yielded the best results at 0%, 40%, and 50% of the RR interval at a pitch of 0.15. The low stenosis was visible at a simulated heart rate of up to 80 bpm. Patency can be detected at heart rates greater than 80 bpm. (orig.)

  9. Mathematical phantoms for evaluation of age-specific internal dose

    International Nuclear Information System (INIS)

    Cristy, M.

    1980-01-01

    A series of mathematical phantoms representing children has been developed for use with photon transport codes. These phantoms, patterned after the Fisher-Snyder adult phantom, consist of simple mathematical expressions for the boundaries of the major organs and body sections. The location and shape of the organs are consistent with drawings depicting developmental anatomy, with the organ volumes assigned such that the masses at the various ages conform closely with the data presented in Reference Man. The explicit mathematical expressions for the various ages overcome the potential misrepresentation of organ sizes that occurred in phantoms derived from simple mathematical transformations of the adult phantom. Female breast tissue has been added to the phantoms, including the adult, now allowing assessment of doses to this organ

  10. Development of thyroid anthropomorphic phantoms for use in nuclear medicine

    Science.gov (United States)

    Cerqueira, R. A. D.; Maia, A. F.

    2014-02-01

    The objective of this study was to develop thyroid anthropomorphic phantoms to be used in control tests of medical images in scintillation cameras. The main difference among the phantoms was the neck shape: in the first, called OSCT, it was geometrically shaped, while in the second, called OSAP, it was anthropomorphically shaped. In both phantoms, thyroid gland prototypes, which were made of acrylic and anthropomorphically shaped, were constructed to allow the simulation of a healthy thyroid and of thyroids with hyperthyroidism and hypothyroidism. Images of these thyroid anthropomorphic phantoms were obtained using iodine 131 with an activity of 8.695 MBq. The iodine 131 was chosen because it is widely used in studies of thyroid scintigraphy. The images obtained proved the effectiveness of the phantoms to simulate normal or abnormal thyroids function. These phantoms can be used in medical imaging quality control programs and, also in the training of professionals involved in the analysis of images in nuclear medicine centers.

  11. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    International Nuclear Information System (INIS)

    Yusof, Mohd Fahmi Mohd; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz; Bauk, Sabar; Hashim, Rokiah

    2015-01-01

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ 2 value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ 2 value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies

  12. Determination of CT number and density profile of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using computed tomography imaging and electron density phantom

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Mohd Fahmi Mohd, E-mail: mfahmi@usm.my; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Bauk, Sabar [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Hashim, Rokiah [School of Industrial Technologies, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-29

    Plug density phantoms were constructed in accordance to CT density phantom model 062M CIRS using binderless, pre-treated and tannin-based Rhizophora Spp. particleboards. The Rhizophora Spp. plug phantoms were scanned along with the CT density phantom using Siemens Somatom Definition AS CT scanner at three CT energies of 80, 120 and 140 kVp. 15 slices of images with 1.0 mm thickness each were taken from the central axis of CT density phantom for CT number and CT density profile analysis. The values were compared to water substitute plug phantom from the CT density phantom. The tannin-based Rhizophora Spp. gave the nearest value of CT number to water substitute at 80 and 120 kVp CT energies with χ{sup 2} value of 0.011 and 0.014 respectively while the binderless Rhizphora Spp. gave the nearest CT number to water substitute at 140 kVp CT energy with χ{sup 2} value of 0.023. The tannin-based Rhizophora Spp. gave the nearest CT density profile to water substitute at all CT energies. This study indicated the suitability of Rhizophora Spp. particleboard as phantom material for the use in CT imaging studies.

  13. SU-G-BRB-01: A Novel 3D Printed Patient-Specific Phantom for Spine SBRT Quality Assurance: Comparison of 3D Printing Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Kim, M; Lee, M; Suh, T [Research Institute of Biomedical Engineering, The Catholic University of Korea, Seoul (Korea, Republic of); Department of Biomedical Engineering, The Catholic University of Korea, Seoul (Korea, Republic of)

    2016-06-15

    Purpose: The novel 3 dimensional (3D)-printed spine quality assurance (QA) phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet, were developed and evaluated for spine stereotactic body radiation treatment (SBRT). Methods: The developed 3D-printed spine QA phantom consisted of an acrylic body and a 3D-printed spine phantom. DLP and Polyjet 3D printers using the high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. To verify dosimetric effects, the novel phantom was made it enable to insert films between each slabs of acrylic body phantom. Also, for measuring internal dose of spine, 3D-printed spine phantom was designed as divided laterally exactly in half. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield unit (HU) was measured based on each CT image. Intensity-modulated radiotherapy plans to deliver a fraction of a 16 Gy dose to a planning target volume (PTV) based on the two 3D-printing techniques were compared for target coverage and normal organ-sparing. Results: Image fusion demonstrated good reproducibility of the fabricated spine QA phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than for the Polyjet-generated phantom. The organs at risk received a lower dose when the DLP technique was used than when the Polyjet technique was used. Conclusion: This study confirmed that a novel 3D-printed phantom mimicking a high-density organ can be created based on CT images, and that a developed 3D-printed spine phantom could be utilized in patient-specific QA for SBRT. Despite using the same main material, DLP and Polyjet yielded different HU values. Therefore, the printing technique and materials must be carefully chosen in order to accurately produce a patient-specific QA phantom.

  14. SU-G-BRB-01: A Novel 3D Printed Patient-Specific Phantom for Spine SBRT Quality Assurance: Comparison of 3D Printing Techniques

    International Nuclear Information System (INIS)

    Lee, S; Kim, M; Lee, M; Suh, T

    2016-01-01

    Purpose: The novel 3 dimensional (3D)-printed spine quality assurance (QA) phantoms generated by two different 3D-printing technologies, digital light processing (DLP) and Polyjet, were developed and evaluated for spine stereotactic body radiation treatment (SBRT). Methods: The developed 3D-printed spine QA phantom consisted of an acrylic body and a 3D-printed spine phantom. DLP and Polyjet 3D printers using the high-density acrylic polymer were employed to produce spine-shaped phantoms based on CT images. To verify dosimetric effects, the novel phantom was made it enable to insert films between each slabs of acrylic body phantom. Also, for measuring internal dose of spine, 3D-printed spine phantom was designed as divided laterally exactly in half. Image fusion was performed to evaluate the reproducibility of our phantom, and the Hounsfield unit (HU) was measured based on each CT image. Intensity-modulated radiotherapy plans to deliver a fraction of a 16 Gy dose to a planning target volume (PTV) based on the two 3D-printing techniques were compared for target coverage and normal organ-sparing. Results: Image fusion demonstrated good reproducibility of the fabricated spine QA phantom. The HU values of the DLP- and Polyjet-printed spine vertebrae differed by 54.3 on average. The PTV Dmax dose for the DLP-generated phantom was about 1.488 Gy higher than for the Polyjet-generated phantom. The organs at risk received a lower dose when the DLP technique was used than when the Polyjet technique was used. Conclusion: This study confirmed that a novel 3D-printed phantom mimicking a high-density organ can be created based on CT images, and that a developed 3D-printed spine phantom could be utilized in patient-specific QA for SBRT. Despite using the same main material, DLP and Polyjet yielded different HU values. Therefore, the printing technique and materials must be carefully chosen in order to accurately produce a patient-specific QA phantom.

  15. Coupled oscillators as models of phantom and scalar field cosmologies

    International Nuclear Information System (INIS)

    Faraoni, Valerio

    2004-01-01

    We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model

  16. Creating 3D gelatin phantoms for experimental evaluation in biomedicine

    Directory of Open Access Journals (Sweden)

    Stein Nils

    2015-09-01

    Full Text Available We describe and evaluate a setup to create gelatin phantoms by robotic 3D printing. Key aspects are the large workspace, reproducibility and resolution of the created phantoms. Given its soft tissue nature, the gelatin is kept fluid during inside the system and we present parameters for additive printing of homogeneous, solid objects. The results indicate that 3D printing of gelatin can be an alternative for quickly creating larger soft tissue phantoms without the need for casting a mold.

  17. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Rulon [Henry Jackson Foundation, Bethesda, Maryland 20817 (United States); Liacouras, Peter [Walter Reed National Military Medical Center, Bethesda, Maryland 20899 (United States); Thomas, Andrew [ATC Healthcare, Washington, District of Columbia 20006 (United States); Kang, Minglei; Lin, Liyong; Simone, Charles B. [Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2015-07-15

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor’s trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between

  18. 3D printing of microtube in solid phantom to simulate tissue oxygenation and perfusion (Conference Presentation)

    Science.gov (United States)

    Lv, Xiang; Xue, Yue; Wang, Haili; Shen, Shu Wei; Zhou, Ximing; Liu, Guangli; Dong, Erbao; Xu, Ronald X.

    2017-03-01

    Tissue-simulating phantoms with interior vascular network may facilitate traceable calibration and quantitative validation of many medical optical devices. However, a solid phantom that reliably simulates tissue oxygenation and blood perfusion is still not available. This paper presents a new method to fabricate hollow microtubes for blood vessel simulation in solid phantoms. The fabrication process combines ultraviolet (UV) rapid prototyping technique with fluid mechanics of a coaxial jet flow. Polydimethylsiloxane (PDMS) and a UV-curable polymer are mixed at the designated ratio and extruded through a coaxial needle device to produce a coaxial jet flow. The extruded jet flow is quickly photo-polymerized by ultraviolet (UV) light to form vessel-simulating solid structures at different sizes ranging from 700 μm to 1000 μm. Microtube structures with adequate mechanical properties can be fabricated by adjusting material compositions and illumination intensity. Curved, straight and stretched microtubes can be formed by adjusting the extrusion speed of the materials and the speed of the 3D printing platform. To simulate vascular structures in biologic tissue, we embed vessel-simulating microtubes in a gel wax phantom of 10 cm x10 cm x 5 cm at the depth from 1 to 2 mm. Bloods at different oxygenation and hemoglobin concentration levels are circulated through the microtubes at different flow rates in order to simulate different oxygenation and perfusion conditions. The simulated physiologic parameters are detected by a tissue oximeter and a laser speckle blood flow meter respectively and compared with the actual values. Our experiments demonstrate that the proposed 3D printing process is able to produce solid phantoms with simulated vascular networks for potential applications in medical device calibration and drug delivery studies.

  19. Initial quality performance results using a phantom to simulate chest computed radiography

    Directory of Open Access Journals (Sweden)

    Muhogora Wilbroad

    2011-01-01

    Full Text Available The aim of this study was to develop a homemade phantom for quantitative quality control in chest computed radiography (CR. The phantom was constructed from copper, aluminium, and polymenthylmethacrylate (PMMA plates as well as Styrofoam materials. Depending on combinations, the literature suggests that these materials can simulate the attenuation and scattering characteristics of lung, heart, and mediastinum. The lung, heart, and mediastinum regions were simulated by 10 mm x 10 mm x 0.5 mm, 10 mm x 10 mm x 0.5 mm and 10 mm x 10 mm x 1 mm copper plates, respectively. A test object of 100 mm x 100 mm and 0.2 mm thick copper was positioned to each region for CNR measurements. The phantom was exposed to x-rays generated by different tube potentials that covered settings in clinical use: 110-120 kVp (HVL=4.26-4.66 mm Al at a source image distance (SID of 180 cm. An approach similar to the recommended method in digital mammography was applied to determine the CNR values of phantom images produced by a Kodak CR 850A system with post-processing turned off. Subjective contrast-detail studies were also carried out by using images of Leeds TOR CDR test object acquired under similar exposure conditions as during CNR measurements. For clinical kVp conditions relevant to chest radiography, the CNR was highest over 90-100 kVp range. The CNR data correlated with the results of contrast detail observations. The values of clinical tube potentials at which CNR is the highest are regarded to be optimal kVp settings. The simplicity in phantom construction can offer easy implementation of related quality control program.

  20. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry

    International Nuclear Information System (INIS)

    Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B.

    2015-01-01

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor’s trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between

  1. 3D printer generated thorax phantom with mobile tumor for radiation dosimetry.

    Science.gov (United States)

    Mayer, Rulon; Liacouras, Peter; Thomas, Andrew; Kang, Minglei; Lin, Liyong; Simone, Charles B

    2015-07-01

    This article describes the design, construction, and properties of an anthropomorphic thorax phantom with a moving surrogate tumor. This novel phantom permits detection of dose both inside and outside a moving tumor and within the substitute lung tissue material. A 3D printer generated the thorax shell composed of a chest wall, spinal column, and posterior regions of the phantom. Images of a computed tomography scan of the thorax from a patient with lung cancer provided the template for the 3D printing. The plastic phantom is segmented into two materials representing the muscle and bones, and its geometry closely matches a patient. A surrogate spherical plastic tumor controlled by a 3D linear stage simulates a lung tumor's trajectory during normal breathing. Sawdust emulates the lung tissue in terms of average and distribution in Hounsfield numbers. The sawdust also provides a forgiving medium that permits tumor motion and sandwiching of radiochromic film inside the mobile surrogate plastic tumor for dosimetry. A custom cork casing shields the film and tumor and eliminates film bending during extended scans. The phantom, lung tissue surrogate, and radiochromic film are exposed to a seven field plan based on an ECLIPSE plan for 6 MV photons from a Trilogy machine delivering 230 cGy to the isocenter. The dose collected in a sagittal plane is compared to the calculated plan. Gamma analysis finds 8.8% and 5.5% gamma failure rates for measurements of large amplitude trajectory and static measurements relative to the large amplitude plan, respectively. These particular gamma analysis results were achieved using parameters of 3% dose and 3 mm, for regions receiving doses >150 cGy. The plan assumes a stationary detection grid unlike the moving radiochromic film and tissues. This difference was experimentally observed and motivated calculated dose distributions that incorporated the phase of the tumor periodic motion. These calculations modestly improve agreement between

  2. Multilayered phantoms with tunable optical properties for a better understanding of light/tissue interactions

    Science.gov (United States)

    Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Vignoud, Séverine; Lavaud, Jonathan; Manfait, Michel; Dinten, Jean-Marc

    2015-03-01

    Light/tissue interactions, like diffuse reflectance, endogenous fluorescence and Raman scattering, are a powerful means for providing skin diagnosis. Instrument calibration is an important step. We thus developed multilayered phantoms for calibration of optical systems. These phantoms mimic the optical properties of biological tissues such as skin. Our final objective is to better understand light/tissue interactions especially in the case of confocal Raman spectroscopy. The phantom preparation procedure is described, including the employed method to obtain a stratified object. PDMS was chosen as the bulk material. TiO2 was used as light scattering agent. Dye and ink were adopted to mimic, respectively, oxy-hemoglobin and melanin absorption spectra. By varying the amount of the incorporated components, we created a material with tunable optical properties. Monolayer and multilayered phantoms were designed to allow several characterization methods. Among them, we can name: X-ray tomography for structural information; Diffuse Reflectance Spectroscopy (DRS) with a homemade fibered bundle system for optical characterization; and Raman depth profiling with a commercial confocal Raman microscope for structural information and for our final objective. For each technique, the obtained results are presented and correlated when possible. A few words are said on our final objective. Raman depth profiles of the multilayered phantoms are distorted by elastic scattering. The signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties, obtained here with DRS, is crucial to properly correct Raman depth profiles. Thus, it would be permitted to consider quantitative studies on skin for drug permeation follow-up or hydration assessment, for instance.

  3. The phantoms of medical and health physics devices for research and development

    CERN Document Server

    Kissick, Michael

    2014-01-01

    A comprehensive overview of all types of phantoms used in medical imaging, therapy, nuclear medicine and health physics is provided in this title. For ionizing radiation, dosimetry with respect to issues of material composition, shape, and motion/position effects are all highlighted. For medical imaging, each type of technology will need specific materials and designs, and the physics and indications will be explored for each type. Health physics phantoms are concerned with some of the same issues such as material heterogeneity, but also unique issues such as organ-specific radiation dose from sources distributed in other organs. Though some of the information enclosed is found in other sources, divided especially along the three categories of imaging, therapy, and health physics, many medical physicists as well as professionals need to bridge these three catagories. Readers will be able to use this book to select the appropriate phantom from a vendor at a clinic, to learn from as a student, to choose materi...

  4. Phantom black holes and critical phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Azreg-Aïnou, Mustapha [Engineering Faculty, Başkent University, Bağlıca Campus, Ankara (Turkey); Marques, Glauber T. [Universidade Federal Rural da Amazônia ICIBE-LASIC, Av. Presidente Tancredo Neves 2501, CEP 66077-901—Belém/PA (Brazil); Rodrigues, Manuel E., E-mail: azreg@baskent.edu.tr, E-mail: gtadaiesky@hotmail.com, E-mail: esialg@gmail.com [Faculdade de Ciências Exatas e Tecnologia, Universidade Federal do Pará, Campus Universitário de Abaetetuba, CEP 68440-000, Abaetetuba, Pará (Brazil)

    2014-07-01

    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.

  5. Dual Energy Tomosynthesis breast phantom imaging

    Science.gov (United States)

    Koukou, V.; Martini, N.; Fountos, G.; Messaris, G.; Michail, C.; Kandarakis, I.; Nikiforidis, G.

    2017-12-01

    Dual energy (DE) imaging technique has been applied to many theoretical and experimental studies. The aim of the current study is to evaluate dual energy in breast tomosynthesis using commercial tomosynthesis system in terms of its potential to better visualize microcalcifications (μCs). The system uses a tungsten target X-ray tube and a selenium direct conversion detector. Low-energy (LE) images were acquired at different tube voltages (28, 30, 32 kV), while high-energy images at 49 kV. Fifteen projections, for the low- and high-energy respectively, were acquired without grid while tube scanned continuously. Log-subtraction algorithm was used in order to obtain the DE images with the weighting factor, w, derived empirically. The subtraction was applied to each pair of LE and HE slices after reconstruction. The TORMAM phantom was imaged with the different settings. Four regions-of-interest including μCs were identified in the inhomogeneous part of the phantom. The μCs in DE images were more clearly visible compared to the low-energy images. Initial results showed that DE tomosynthesis imaging is a promising modality, however more work is required.

  6. Characterization of tracked radiofrequency ablation in phantom

    International Nuclear Information System (INIS)

    Chen, Chun-Cheng R.; Miga, Michael I.; Galloway, Robert L.

    2007-01-01

    In radiofrequency ablation (RFA), successful therapy requires accurate, image-guided placement of the ablation device in a location selected by a predictive treatment plan. Current planning methods rely on geometric models of ablations that are not sensitive to underlying physical processes in RFA. Implementing plans based on computational models of RFA with image-guided techniques, however, has not been well characterized. To study the use of computational models of RFA in planning needle placement, this work compared ablations performed with an optically tracked RFA device with corresponding models of the ablations. The calibration of the tracked device allowed the positions of distal features of the device, particularly the tips of the needle electrodes, to be determined to within 1.4±0.6 mm of uncertainty. Ablations were then performed using the tracked device in a phantom system based on an agarose-albumin mixture. Images of the sliced phantom obtained from the ablation experiments were then compared with the predictions of a bioheat transfer model of RFA, which used the positional data of the tracked device obtained during ablation. The model was demonstrated to predict 90% of imaged pixels classified as being ablated. The discrepancies between model predictions and observations were analyzed and attributed to needle tracking inaccuracy as well as to uncertainties in model parameters. The results suggest the feasibility of using finite element modeling to plan ablations with predictable outcomes when implemented using tracked RFA

  7. Phantom Eye Syndrome: A Review of the Literature

    Directory of Open Access Journals (Sweden)

    Agda M. Andreotti

    2014-01-01

    Full Text Available The purpose of this literature review was to describe the main features of phantom eye syndrome in relation to their possible causes, symptoms, treatments, and influence of eye amputation on quality of life of anophthalmic patients. For this, a bibliographical research was performed in Pubmed database using the following terms: “eye amputation,” “eye trauma,” “phantom eye syndrome,” “phantom pain,” and “quality of life,” associated or not. Thirteen studies were selected, besides some relevant references contained in the selected manuscripts and other studies hallowed in the literature. Thus, 56 articles were included in this review. The phantom eye syndrome is defined as any sensation reported by the patient with anophthalmia, originated anophthalmic cavity. In phantom eye syndrome, at least one of these three symptoms has to be present: phantom vision, phantom pain, and phantom sensations. This syndrome has a direct influence on the quality of life of the patients, and psychological support is recommended before and after the amputation of the eyeball as well as aid in the treatment of the syndrome. Therefore, it is suggested that, for more effective treatment of phantom eye syndrome, drug therapy should be associated with psychological approach.

  8. Phantoms for IMRT dose distribution measurement and treatment verification

    International Nuclear Information System (INIS)

    Low, Daniel A.; Gerber, Russell L.; Mutic, Sasa; Purdy, James A.

    1998-01-01

    Background: The verification of intensity-modulated radiation therapy (IMRT) patient treatment dose distributions is currently based on custom-built or modified dose measurement phantoms. The only commercially available IMRT treatment planning and delivery system (Peacock, NOMOS Corp.) is supplied with a film phantom that allows accurate spatial localization of the dose distribution using radiographic film. However, measurements using other dosimeters are necessary for the thorough verification of IMRT. Methods: We have developed a phantom to enable dose measurements using a cylindrical ionization chamber and the localization of prescription isodose curves using a matrix of thermoluminescent dosimetry (TLD) chips. The external phantom cross-section is identical to that of the commercial phantom, to allow direct comparisons of measurements. A supplementary phantom has been fabricated to verify the IMRT dose distributions for pelvis treatments. Results: To date, this phantom has been used for the verification of IMRT dose distributions for head and neck and prostate cancer treatments. Designs are also presented for a phantom insert to be used with polymerizing gels (e.g., BANG-2) to obtain volumetric dose distribution measurements. Conclusion: The phantoms have proven useful in the quantitative evaluation of IMRT treatments

  9. Development of thyroid anthropomorphic phantoms for use in nuclear medicine

    International Nuclear Information System (INIS)

    Cerqueira, R.A.D.; Maia, A.F.

    2014-01-01

    The objective of this study was to develop thyroid anthropomorphic phantoms to be used in control tests of medical images in scintillation cameras. The main difference among the phantoms was the neck shape: in the first, called OSCT, it was geometrically shaped, while in the second, called OSAP, it was anthropomorphically shaped. In both phantoms, thyroid gland prototypes, which were made of acrylic and anthropomorphically shaped, were constructed to allow the simulation of a healthy thyroid and of thyroids with hyperthyroidism and hypothyroidism. Images of these thyroid anthropomorphic phantoms were obtained using iodine 131 with an activity of 8.695 MBq. The iodine 131 was chosen because it is widely used in studies of thyroid scintigraphy. The images obtained proved the effectiveness of the phantoms to simulate normal or abnormal thyroids function. These phantoms can be used in medical imaging quality control programs and, also in the training of professionals involved in the analysis of images in nuclear medicine centers. - Highlights: ► Two thyroid phantoms were developed (OSCT and OSAP) with different types of acrylics. ► Thyroid glands were represented anthropomorphically in the both phantoms. ► Different prototypes of thyroid were built of simulate healthy or unhealthy glands. ► Images indicate that anthropomorphic phantoms correctly simulate the thyroid gland

  10. Breast phantom for mammary tissue characterization by near infrared spectroscopy

    International Nuclear Information System (INIS)

    Miranda, D A; Cristiano, K L; Gutiérrez, J C

    2013-01-01

    Breast cancer is a disease associated to a high morbidity and mortality in the entire world. In the study of early detection of breast cancer the development of phantom is so important. In this research we fabricate a breast phantom using a ballistic gel with special modifications to simulate a normal and abnormal human breast. Optical properties of woman breast in the near infrared region were modelled with the phantom we developed. The developed phantom was evaluated with near infrared spectroscopy in order to study its relation with breast tissue. A good optical behaviour was achieved with the model fabricated

  11. A multimodality vascular imaging phantom of an abdominal aortic aneurysm with a visible thrombus

    Energy Technology Data Exchange (ETDEWEB)

    Allard, Louise; Chayer, Boris; Qin Zhao [Laboratory of Biorheology and Medical Ultrasonics, Research Center, University of Montreal Hospital (CRCHUM), Quebec H2L 2W5 (Canada); Soulez, Gilles [Department of Radiology, University of Montreal Hospital (CHUM), Quebec H2L 2M1 (Canada); Department of Radiology, Radio-Oncology and Nuclear Medicine, University of Montreal, Quebec H3T 1J4 (Canada); Institute of Biomedical Engineering, University of Montreal, Quebec H3T 1J4 (Canada); Roy, David [Institute of Biomedical Engineering, University of Montreal, Quebec H3T 1J4 (Canada); Cloutier, Guy [Laboratory of Biorheology and Medical Ultrasonics, Research Center, University of Montreal Hospital (CRCHUM), Quebec H2L 2W5 (Canada); Department of Radiology, Radio-Oncology and Nuclear Medicine, University of Montreal, Quebec H3T 1J4 (Canada); Institute of Biomedical Engineering, University of Montreal, Quebec H3T 1J4 (Canada)

    2013-06-15

    Purpose: With the continuous development of new stent grafts and implantation techniques, it has now become technically feasible to treat abdominal aortic aneurysms (AAA) with challenging anatomy using endovascular repair with standard, fenestrated, or branched stent-grafts. In vitro experimentations are very useful to improve stent-graft design and conformability or imaging guidance for stent-graft delivery or follow-up. Vascular replicas also help to better understand the limitation of endovascular approaches in challenging anatomy and possibly improve surgical planning or training by practicing high risk clinical procedures in the laboratory to improve outcomes in the operating room. Most AAA phantoms available have a very basic anatomy, which is not representative of the clinical reality. This paper presents a method of fabrication of a realistic AAA phantom with a visible thrombus, as well as some mechanical properties characterizing such phantom. Methods: A realistic AAA geometry replica of a real patient anatomy taken from a multidetector computed tomography (CT) scan was manufactured. To demonstrate the multimodality imaging capability of this new phantom with a thrombus visible in magnetic resonance (MR) angiography, CT angiography (CTA), digital subtraction angiography (DSA), and ultrasound, image acquisitions with all these modalities were performed by using standard clinical protocols. Potential use of this phantom for stent deployment was also tested. A rheometer allowed defining hyperelastic and viscoelastic properties of phantom materials. Results: MR imaging measurements of SNR and CNR values on T1 and T2-weighted sequences and MR angiography indicated reasonable agreement with published values of AAA thrombus and abdominal components in vivo. X-ray absorption also lay within normal ranges of AAA patients and was representative of findings observed on CTA, fluoroscopy, and DSA. Ultrasound propagation speeds for developed materials were also in

  12. A multimodality vascular imaging phantom of an abdominal aortic aneurysm with a visible thrombus

    International Nuclear Information System (INIS)

    Allard, Louise; Chayer, Boris; Qin Zhao; Soulez, Gilles; Roy, David; Cloutier, Guy

    2013-01-01

    Purpose: With the continuous development of new stent grafts and implantation techniques, it has now become technically feasible to treat abdominal aortic aneurysms (AAA) with challenging anatomy using endovascular repair with standard, fenestrated, or branched stent-grafts. In vitro experimentations are very useful to improve stent-graft design and conformability or imaging guidance for stent-graft delivery or follow-up. Vascular replicas also help to better understand the limitation of endovascular approaches in challenging anatomy and possibly improve surgical planning or training by practicing high risk clinical procedures in the laboratory to improve outcomes in the operating room. Most AAA phantoms available have a very basic anatomy, which is not representative of the clinical reality. This paper presents a method of fabrication of a realistic AAA phantom with a visible thrombus, as well as some mechanical properties characterizing such phantom. Methods: A realistic AAA geometry replica of a real patient anatomy taken from a multidetector computed tomography (CT) scan was manufactured. To demonstrate the multimodality imaging capability of this new phantom with a thrombus visible in magnetic resonance (MR) angiography, CT angiography (CTA), digital subtraction angiography (DSA), and ultrasound, image acquisitions with all these modalities were performed by using standard clinical protocols. Potential use of this phantom for stent deployment was also tested. A rheometer allowed defining hyperelastic and viscoelastic properties of phantom materials. Results: MR imaging measurements of SNR and CNR values on T1 and T2-weighted sequences and MR angiography indicated reasonable agreement with published values of AAA thrombus and abdominal components in vivo. X-ray absorption also lay within normal ranges of AAA patients and was representative of findings observed on CTA, fluoroscopy, and DSA. Ultrasound propagation speeds for developed materials were also in

  13. Experimental phantom lesion detectability study using a digital breast tomosynthesis prototype system

    International Nuclear Information System (INIS)

    Schulz-Wendtland, R.; Wenkel, E.; Lell, M.; Boehner, C.; Bautz, W.A.; Mertelmeier, T.

    2006-01-01

    Purpose: To compare the sensitivity of conventional two-dimensional (2D) projection imaging with tomosynthesis with respect to the detectability of mammographic phantom lesions. Materials and Methods: Using a breast tomosynthesis prototype based on a commercial FFDM system (Siemens MAMMOMAT Novation DR ), but modified for a wide angle tube motion and equipped with a fast read-out amorphous selenium detector, we acquired standard 2D images and tomosynthesis series of projection views. We used the Wisconsin mammographic random phantom, model RMI 152A. The anode filter combinations Mo/Mo and W/Rh at two different doses were used as typical radiographic techniques. Slice images through the phantom parallel to the detector were reconstructed with a distance of 1 mm employing a filtered back-projection algorithm. The image data sets were read by five radiologists and evaluated with respect to the detectability of the phantom details. Results: For all studied radiographic techniques, the detection rate in the tomosynthesis mode was 100%, i.e. 75 true positive findings out of 75 possible hits. In contrast, the conventional projection mode yielded a detection rate between 80 and 93% (corresponding to 60 and 70 detected details) depending on the dose and X-ray spectrum. Conclusion: Tomosynthesis has the potential to increase the sensitivity of digital mammography. Overlapping structures from out-of-plane tissue can be removed in the tomosynthesis reconstruction process, thereby enhancing the diagnostic accuracy. (orig.)

  14. Construction of pediatric homogeneous phantoms for optimization of chest and skull radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Allan Felipe Fattori, E-mail: allan@ibb.unesp.br [Instituto de Biociências de Botucatu, P.O. BOX 510, Departamento de Física e Biofísica, UNESP—Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo (Brazil); Miranda, José Ricardo de Arruda, E-mail: jmiranda@ibb.unesp.br [Instituto de Biociências de Botucatu, Departamento de Física e Biofísica, UNESP—Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo (Brazil); Bacchim Neto, Fernando Antonio, E-mail: fernando.bacchim@gmail.com [Instituto de Biociências de Botucatu, Departamento de Física e Biofísica, UNESP—Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo (Brazil); Duarte, Sérgio Barbosa, E-mail: sbd@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Laboratório de Altas Energias, Dr. Xavier Sigaud, 150, Rio de Janeiro, 22290-180 Rio de Janeiro (Brazil); Pina, Diana Rodrigues de, E-mail: drpina@fmb.unesp.br [Departamento de Doenças Tropicais e Diagnóstico por Imagem, Faculdade de Medicina de Botucatu, UNESP—Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Botucatu, 18618-000 São Paulo (Brazil)

    2015-08-15

    Highlights: • We developed two pediatric patient-equivalent phantoms. • Our phantoms were used in the optimization process of computed radiography systems. • We evaluated physical quantities such as effective detective quantum efficiency and contrast-to-noise ratio. • We determined optimized techniques for pediatric protocols. - Abstract: Objectives: To develop two pediatric patient-equivalent phantoms, the Pediatric Chest Equivalent Patient (PCEP) and the Pediatric Skull Equivalent Patient (PSEP) for children aged 1 to 5 years. We also used both phantoms for image quality evaluations in computed radiography systems to determine Gold Standard (GS) techniques for pediatric patients. Methods: To determine the simulator materials thickness (Lucite and aluminum), we quantified biological tissues (lung, soft, and bone) using an automatic computational algorithm. To objectively establish image quality levels, two physical quantities were used: effective detective quantum efficiency and contrast-to-noise ratio. These quantities were associated to values obtained for standard patients from previous studies. Results: For chest radiographies, the GS technique applied was 81 kVp, associated to 2.0 mAs and 83.6 μGy of entrance skin dose (ESD), while for skull radiographies, the GS technique was 70 kVp, associated to 5 mAs and 339 μGy of ESD. Conclusion: This procedure allowed us to choose optimized techniques for pediatric protocols, thus improving quality of diagnosis for pediatric population and reducing diagnostic costs to our institution. These results could also be easily applied to other services with different equipment technologies.

  15. A comparison of digital and screen-film mammography using quality control phantoms

    International Nuclear Information System (INIS)

    Undrill, Peter E.; O'Kane, Arlene D.; Gilbert, Fiona J.

    2000-01-01

    AIM: To compare the performance of a direct digital mammography system with normal-view and magnified-view conventional screen-film methods using quality control phantoms. MATERIALS AND METHODS: Using a Siemens Mammomat [reg] 3000 and an Opdima [reg] digital spot imaging and biopsy attachment, film and direct digital images of two phantoms [DuPont and TOR (MAM)] were obtained under normal operating conditions. These were assessed by three groups of observers with differing expertise -- radiologists, radiographers and medical physicists. Each observer was asked to compare the direct digital image with films taken in standard view and magnified view, providing scores for object visibility and confidence. For the digital images, observers were allowed to vary the image presentation parameters. RESULTS: Both phantoms showed that overall the direct digital view and the magnified view film performed significantly better (P < 0.05) than standard view film. For certain small or low contrast objects the differences became very highly significant (P < 0.001). CONCLUSION: Only the TOR (MAM) phantom showed any significant difference between digital and magnified modalities, with magnified views performing better for fine, faint filaments and digital acquisition better for low contrast objects. Almost no difference existed between the three observer groups. Undrill, P.E. (2000). Clinical Radiology 53, 782-790

  16. Development of a realistic, dynamic digital brain phantom for CT perfusion validation

    Science.gov (United States)

    Divel, Sarah E.; Segars, W. Paul; Christensen, Soren; Wintermark, Max; Lansberg, Maarten G.; Pelc, Norbert J.

    2016-03-01

    Physicians rely on CT Perfusion (CTP) images and quantitative image data, including cerebral blood flow, cerebral blood volume, and bolus arrival delay, to diagnose and treat stroke patients. However, the quantification of these metrics may vary depending on the computational method used. Therefore, we have developed a dynamic and realistic digital brain phantom upon which CTP scans can be simulated based on a set of ground truth scenarios. Building upon the previously developed 4D extended cardiac-torso (XCAT) phantom containing a highly detailed brain model, this work consisted of expanding the intricate vasculature by semi-automatically segmenting existing MRA data and fitting nonuniform rational B-spline surfaces to the new vessels. Using time attenuation curves input by the user as reference, the contrast enhancement in the vessels changes dynamically. At each time point, the iodine concentration in the arteries and veins is calculated from the curves and the material composition of the blood changes to reflect the expected values. CatSim, a CT system simulator, generates simulated data sets of this dynamic digital phantom which can be further analyzed to validate CTP studies and post-processing methods. The development of this dynamic and realistic digital phantom provides a valuable resource with which current uncertainties and controversies surrounding the quantitative computations generated from CTP data can be examined and resolved.

  17. Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

    Science.gov (United States)

    Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

    2006-11-01

    The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

  18. Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner

    International Nuclear Information System (INIS)

    Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

    2006-01-01

    The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections. (author)

  19. Design, fabrication and evaluation of a new calibration phantom for in vivo measurement of bone-seeking radionuclides (invited paper)

    International Nuclear Information System (INIS)

    Spitz, H.B.; Lodwick, J.

    2000-01-01

    A new anthropometric phantom has been developed for use in calibrating in vivo measurements of bone-seeking radionuclides. The phantom has the external shape and appearance of the human adult knee and contains a realistic femur, patella, tibia, and fibula. Unique formulations of polyurethanes, CaCo 3 , and other trace materials are used in construction of the phantom to produce substitutes for human tissue having the same density, attenuation coefficient, and effective Z as that of human muscle and trabecular bone. The formulation for trabecular bone includes provision for a precisely known quantity of radioactive material that is either uniformly distributed throughout the bone matrix or deposited on the exterior surface. The knee phantom is assembled in three interlocking sections that simplify inserting the skeletal structures and prevent streaming. One or more detectors can easily be positioned on the top or sides of the phantom. Intercomparison measurements of 241 Am in bone using separate arrays of phoswich and germanium detectors demonstrate that a single knee phantom exhibits the same detection efficiency as that using the skull. In vivo measurement of the knee is a desirable alternative to the head if facial contamination is present or when evaluating recent exposure to bone seeking radionuclides, since bones of the knee exhibit more rapid uptake than the skull. In practice, greater measurement efficiency can be obtained by placing detectors over both knees since a larger fraction of the total body activity is observed. Calibration measurements using the new anthropometric knee phantom demonstrate that it is durable, easy to use, and provides consistent results over repeated measurements. (author)

  20. The design and evaluation of a phantom for the audit of the treatment chain for prostate radiotherapy

    International Nuclear Information System (INIS)

    Perrin, Bruce A.; Jordan, Thomas J.; Hounsell, Alan R.

    2001-01-01

    Background and Purpose: A phantom has been designed and built for a multi-institutional technique audit of the planning and delivery for radiotherapy to the prostate. The phantom was designed to test both the geometric and dosimetric accuracy of each aspect of the process. Materials and Methods: The phantom consists of two curved water filled perspex tanks either side of a central block of solid water equivalent material. There are two options for the central section; a target defining block and a dose measurement block. The target defining block uses air holes to define a 3-D target volume for imaging via a CT scanner or a simulator. These holes can subsequently be filled with steel pins to allow megavoltage imaging. The dose measurement block allows thimble chamber measurements to be made at pre-selected points in a 5x5mm array. Five dose measurement points, typical for a prostate planning target volume (PTV) were selected. Initial evaluation of the phantom was performed by auditing the prostate radiotherapy planning and treatment chain at one institution. Results: Agreement between the phantom and planned geometry confirmed that the stages of image acquisition, transfer and manipulation were accurately performed. Agreement within 0.5% was found between phantom and water tank measurements for dose calibration at a reference point. The measured dose delivered was within 2% of the dose calculated by the planning computer for all of the selected measurement points. The target volume marked by the steel pins was visible using electronic portal imaging. Conclusions: The phantom is a useful tool for the technique audit of prostate radiotherapy

  1. Usefulness of a functional tracheobronchial phantom for interventional procedure

    International Nuclear Information System (INIS)

    Kim, Tae Hyung; Lim, Cheong Hwan; Kim, Jeong Koo

    2003-01-01

    To evaluate usefulness of a functional tracheobronchial phantom for interventional procedure. The functional phantom was made as a actual size with human normal anatomy used silicone and a paper clay mold. A tracheobronchial-shape clay mold was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed. We measured film density and tracheobronchial angle at the human, animal and phantom respectively. The film density of trachea part were 0.76 (± 0.011) in human, 0.97 (± 0.015) in animal, 0.45 (± 0.016) in phantom. The tracheobronchial bifurcation part measured 0.51 (± 0.006) in human, 0.65 (± 0.005) in animal, 0.65 (± 0.008) in phantom. The right bronchus part measured 0.14 (± 0.008) in human, 0.59 (± 0.014) in animal and 0.04 (± 0.007) in phantom. The left bronchus were 0.54 (± 0.004) in human, 0.54 (± 0.008) in animal and 0.08 (± 0.008) in phantom. At the stent part were 0.54 (± 0.004) in human, 0.59 (± 0.011) in animal and 0.04 (± 0.007) in phantom, respectively. The tracheobronchial angle of the left bronchus site were 42.6 (± 2.07).deg. in human, 43.4 (± 2.40).deg. in animal and 35 (± 2.00).deg. in phantom, respectively. The right bronchus site were 32.8 (± 2.77).deg. in human, 34.6 (± 1.94).deg. in animal and 50.2 (± 1.30).deg. in phantom, respectively. The phantom was useful for in-vitro testing of tracheobronchial interventional procedure, since it was easy to reproduce

  2. Computational voxel phantom, associated to anthropometric and anthropomorphic real phantom for dosimetry in human male pelvis radiotherapy

    International Nuclear Information System (INIS)

    Silva, Cleuza Helena Teixeira; Campos, Tarcisio Passos Ribeiro de

    2005-01-01

    This paper addresses a computational model of voxels through MCNP5 Code and the experimental development of an anthropometric and anthropomorphic phantom for dosimetry in human male pelvis brachytherapy focusing prostatic tumors. For elaboration of the computational model of the human male pelvis, anatomical section images from the Visible Man Project were applied. Such selected and digital images were associated to a numeric representation, one for each section. Such computational representation of the anatomical sections was transformed into a bi-dimensional mesh of equivalent tissue. The group of bidimensional meshes was concatenated forming the three-dimensional model of voxels to be used by the MCNP5 code. In association to the anatomical information, data from the density and chemical composition of the basic elements, representatives of the organs and involved tissues, were setup in a material database for the MCNP-5. The model will be applied for dosimetric evaluations in situations of irradiation of the human masculine pelvis. Such 3D model of voxel is associated to the code of transport of particles MCNP5, allowing future simulations. It was also developed the construction of human masculine pelvis phantom, based on anthropometric and anthropomorphic dates and in the use of representative equivalent tissues of the skin, fatty, muscular and glandular tissue, as well as the bony structure.This part of work was developed in stages, being built the bony cast first, later the muscular structures and internal organs. They were then jointly mounted and inserted in the skin cast. The representative component of the fatty tissue was incorporate and accomplished the final retouchings in the skin. The final result represents the development of two important essential tools for elaboration of computational and experimental dosimetry. Thus, it is possible its use in calibrations of pre-existent protocols in radiotherapy, as well as for tests of new protocols, besides

  3. Measurement of hard tissue density of head phantom based on the HU by using CBCT

    International Nuclear Information System (INIS)

    Kim, Moon Sun; Kang, Dong Wan; Kim, Jae Duk

    2009-01-01

    The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density (g cm -3 ) obtained from cone-beam computed tomography (CBMercuRay TM ) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the CBMercuRay TM (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using CBWorks TM . Linear regression analysis and Student t-test were performed statistically. There was no significant difference (P>0.54) between real densities and measured densities. A linear regression was performed using the density, ρ (g cm -3 ), as the dependent variable in terms of the HU (H). The regression equation obtained was ρ=0.00072 H-0.01588 with an R2 value of 0.9968. Density values based on the Hounsfield scale was 1697.1 ± 24.9 HU in cortical bone, 526.5 ± 44.4 HU in trabecular bone, 2639.1 ± 48.7 HU in enamel, 1246.1 ± 39.4 HU in dentin of dental head phantom. CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

  4. Use of a modified natural-rubber phantom for radiotherapy dosimetry measurements

    International Nuclear Information System (INIS)

    Bradley, D.A.; Ng, K.-H.; Aziz, Y.B.

    1988-01-01

    The utility of a phantom material, based on SMR(L) [Standard Malaysian Rubber] grade natural rubber and a formulation used for the proprietary rubber phantom-material, Temex, has been examined for the 1-MeV photon-energy range using γ radiation from a 60 Co source. Measurement has also been performed with 60-keV photons using the radionuclide 241 Am. At photon-therapy energy levels the measured response, when compared with tabulated central-axis percentage depth doses for defined measuring conditions, produces everywhere (in the range 1-19 cm depth) better than 2% deviation. The favourable measured response characteristics combined with the ease of processing and casting the phantom material provide the basis for useful radiotherapy machine calibration and anthropomorphic dosimetry measurements. The measured mass-attenuation coefficient, at 60 keV, of 0.204 cm 2 g -1 (± 3%) is in close agreement with tabulated values for water (0.2055 cm 2 g -1 ). (author)

  5. Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy; Resposta radiologica e dosimetria em phantom fisico de cabeca e pescoco para radioterapia conformacional 3D

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Larissa

    2013-07-01

    Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

  6. Digital subtraction angiography system evaluation with phantoms

    International Nuclear Information System (INIS)

    Wenstrup, R.S.; Sweeney, K.P.; Scholz, F.J.

    1985-01-01

    Advances in digital subtraction angiography imaging demonstrate the need for critical evaluation of the performance of digital subtraction equipment. The design of a phantom set for noninvasive assessment of the imaging quality of digital subtraction equipment is described; components include a remotely controlled transport system and individual patterns to evaluate the contrast and detail properties of the image intensifier, low-contrast sensitivity and resolution of the system, geometric distortion of image, linearity, mechanical and electronic stability of equipment, and effects of bone and bowel gas on iodine perception. The performance of an add-on digital radiographic system is presented, along with radiation exposure levels at the image intensifier for a range of radiographic techniques

  7. Phantom Limb Pain in Pediatric Oncology

    Directory of Open Access Journals (Sweden)

    Patrick DeMoss

    2018-04-01

    Full Text Available Phantom limb pain (PLP is a prevalent problem for children and adolescents undergoing amputation due to cancer treatment. The symptoms are wide ranging from sharp to tingling. PLP in children typically lasts for a few minutes but can be almost constant and can be highly distressing. This focused review describes the characteristics, epidemiology, mechanisms, and evidence-based treatment of PLP in pediatric populations, focusing on pediatric cancer. In pediatric oncology, the administration of chemotherapy is a risk factor that potentially sensitizes the nervous system and predisposes pediatric cancer patients to develop PLP after amputation. Gabapentin, tricyclic antidepressants, opiates, nerve blocks, and epidural catheters have shown mixed success in adults and case reports document potential utility in pediatric patients. Non-pharmacologic treatments, such as mirror therapy, psychotherapy, and acupuncture have also been used in pediatric PLP with success. Prospective controlled trials are necessary to advance care for pediatric patients with PLP.

  8. Comparison of different phantoms used in digital diagnostic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bor, Dogan, E-mail: bor@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics. Tandogan, 06100 Ankara (Turkey); Unal, Elif, E-mail: elf.unall@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey); Uslu, Anil, E-mail: m.aniluslu@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey)

    2015-09-21

    The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

  9. Anisotropic Bianchi-I universe with phantom field and cosmological ...

    Indian Academy of Sciences (India)

    India. *Corresponding author. E-mail: bcpaul@iucaa.ernet.in. MS received 23 May ... We study an anisotropic Bianchi-I universe in the presence of a phantom ... The phantom cosmology has been analysed adopting phase space analysis ... the second part we study the critical points corresponding to the set of autonomous.

  10. Phantom jam avoidance through in-car speed advice

    NARCIS (Netherlands)

    Suijs, L.C.W.; Wismans, Luc Johannes Josephus; Krol, L.; van Berkum, Eric C.

    2015-01-01

    The existence of phantom jams can be explained following the definition of Kerner & Konhäuser (1993) who state that a phantom jam occurs without the existence of a physical bottleneck and is caused by the imperfect driving style of road users under metastable traffic conditions. In order to prevent

  11. Phantom limb phenomenon as an example of body image distortion

    Directory of Open Access Journals (Sweden)

    Razmus Magdalena

    2017-06-01

    Full Text Available Introduction: The perception of one’s own body, its mental representation, and emotional attitude to it are the components of so-called “body image” [1]. The aim of the research was to analyse phantom pain and non-painful phantom sensations as results of limb loss and to explain them in terms of body image distortion.

  12. Nonvisualized ('Phantom') renal calyx: Causes and radiological approach to diagnosis

    International Nuclear Information System (INIS)

    Brennan, R.E.; Pollack, H.M.

    1979-01-01

    A calyx which fails completely to opacify on excretory urography (phantom calyx) is often the harbinger of serious underlying renal disease. Causes of a phantom calyx include tuberculosis, tumor, calculus, ischemia, trauma, and congenital anomaly. The pathololgic basis for the radiographic findings in each of these entities is described and an overall approach to diagnosis is set forth. (orig.) [de

  13. Evaluation of DQA for tomography using 3D volumetric phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Uk [Dept. of Radiation Oncology, Catholic University of Incheon St. Mary' s Hospital, Incheon (Korea, Republic of); Kim, Jeong Koo [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of)

    2016-12-15

    The study investigates the necessity of 3 dimensional dose distribution evaluation instead of point dose and 2 dimensional dose distribution evaluation. Treatment plans were generated on the RANDO phantom to measure the precise dose distribution of the treatment site 0.5, 1, 1.5, 2, 2.5, 3 cm with the prescribed dose; 1,200 cGy, 5 fractions. Gamma analysis (3%/3 mm, 2%/2 mm) of dose distribution was evaluated with gafchromic EBT2 film and ArcCHECK phantom. The average error of absolute dose was measured at 0.76±0.59% and 1.37±0.76% in cheese phantom and ArcCHECK phantom respectively. The average passing ratio for 3%/3 mm were 97.72±0.02% and 99.26±0.01% in gafchromic EBT2 film and ArcCHECK phantom respectively. The average passing ratio for 2%/2 mm were 94.21±0.02% and 93.02±0.01% in gafchromic EBT2 film and ArcCHECK phantom respectively. There was a more accurate dose distribution of 3D volume phantom than cheese phantom in patients DQA using tomotherapy. Therefor it should be evaluated simultaneously 3 dimensional dose evaluation on target and peripheral area in rotational radiotherapy such as tomotherapy.

  14. Anisotropic Bianchi-I universe with phantom field and cosmological ...

    Indian Academy of Sciences (India)

    We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the ...

  15. Development of the Reference Korean Female Voxel Phantom

    International Nuclear Information System (INIS)

    Ham, Bo Kyoung; Cho, Kun Woo; Yeom, Yoen Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol

    2012-01-01

    The objective of this study is for development of the reference Korean female phantom, HDRK-Woman. The phantom was constructed by adjusting a Korean woman voxel phantom to the Reference Korean data. The Korean woman phantom had been developed based on the high-resolution color slice images obtained from an adult Korean female cadaver. There were a total of 39 organs including the 27 organs specified in ICRP 103 for effective dose calculation. The voxel resolution of the phantom was 1.967 X 1.967 X X 2.0619 mm 3 and the voxel array size is 261 X 109 X 825 in the x, y and z directions. Then, the voxel resolution was changed to 2.0351 X 2.0351 X 2.0747 mm 3 for adjustment of the height and total bone mass of the phantom to the Reference Korean data. Finally, the internal organs and tissue were adjusted using in-house software program developed for 3D volume adjustment of the organs and tissue. The effective dose values of HDRK phantoms were calculated for broad parallel photon beams using MCNPX Monte Carlo code and compared with those of ICRP phantoms.

  16. Development of the Reference Korean Female Voxel Phantom

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Bo Kyoung; Cho, Kun Woo [University of Science and Technology, Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Yeom, Yoen Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol [Hanyang University, Seoul (Korea, Republic of)

    2012-03-15

    The objective of this study is for development of the reference Korean female phantom, HDRK-Woman. The phantom was constructed by adjusting a Korean woman voxel phantom to the Reference Korean data. The Korean woman phantom had been developed based on the high-resolution color slice images obtained from an adult Korean female cadaver. There were a total of 39 organs including the 27 organs specified in ICRP 103 for effective dose calculation. The voxel resolution of the phantom was 1.967 X 1.967 X X 2.0619 mm{sup 3} and the voxel array size is 261 X 109 X 825 in the x, y and z directions. Then, the voxel resolution was changed to 2.0351 X 2.0351 X 2.0747 mm{sup 3} for adjustment of the height and total bone mass of the phantom to the Reference Korean data. Finally, the internal organs and tissue were adjusted using in-house software program developed for 3D volume adjustment of the organs and tissue. The effective dose values of HDRK phantoms were calculated for broad parallel photon beams using MCNPX Monte Carlo code and compared with those of ICRP phantoms.

  17. The impact of anthropometric patient-phantom matching on organ dose: A hybrid phantom study for fluoroscopy guided interventions

    International Nuclear Information System (INIS)

    Johnson, Perry B.; Geyer, Amy; Borrego, David; Ficarrotta, Kayla; Johnson, Kevin; Bolch, Wesley E.

    2011-01-01

    Purpose: To investigate the benefits and limitations of patient-phantom matching for determining organ dose during fluoroscopy guided interventions. Methods: In this study, 27 CT datasets representing patients of different sizes and genders were contoured and converted into patient-specific computational models. Each model was matched, based on height and weight, to computational phantoms selected from the UF hybrid patient-dependent series. In order to investigate the influence of phantom type on patient organ dose, Monte Carlo methods were used to simulate two cardiac projections (PA/left lateral) and two abdominal projections (RAO/LPO). Organ dose conversion coefficients were then calculated for each patient-specific and patient-dependent phantom and also for a reference stylized and reference hybrid phantom. The coefficients were subsequently analyzed for any correlation between patient-specificity and the accuracy of the dose estimate. Accuracy was quantified by calculating an absolute percent difference using the patient-specific dose conversion coefficients as the reference. Results: Patient-phantom matching was shown most beneficial for estimating the dose to heavy patients. In these cases, the improvement over using a reference stylized phantom ranged from approximately 50% to 120% for abdominal projections and for a reference hybrid phantom from 20% to 60% for all projections. For lighter individuals, patient-phantom matching was clearly superior to using a reference stylized phantom, but not significantly better than using a reference hybrid phantom for certain fields and projections. Conclusions: The results indicate two sources of error when patients are matched with phantoms: Anatomical error, which is inherent due to differences in organ size and location, and error attributed to differences in the total soft tissue attenuation. For small patients, differences in soft tissue attenuation are minimal and are exceeded by inherent anatomical differences

  18. Cosmological perturbations on the phantom brane

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Satadru; Sahni, Varun [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Viznyuk, Alexander; Shtanov, Yuri, E-mail: satadru@iucaa.in, E-mail: viznyuk@bitp.kiev.ua, E-mail: shtanov@bitp.kiev.ua, E-mail: varun@iucaa.in [Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine)

    2016-07-01

    We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, w {sub eff} < −1, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom—the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which results in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch ( z ∼< 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.

  19. Development of anatomically and dielectrically accurate breast phantoms for microwave imaging applications

    Science.gov (United States)

    O'Halloran, M.; Lohfeld, S.; Ruvio, G.; Browne, J.; Krewer, F.; Ribeiro, C. O.; Inacio Pita, V. C.; Conceicao, R. C.; Jones, E.; Glavin, M.

    2014-05-01

    Breast cancer is one of the most common cancers in women. In the United States alone, it accounts for 31% of new cancer cases, and is second only to lung cancer as the leading cause of deaths in American women. More than 184,000 new cases of breast cancer are diagnosed each year resulting in approximately 41,000 deaths. Early detection and intervention is one of the most significant factors in improving the survival rates and quality of life experienced by breast cancer sufferers, since this is the time when treatment is most effective. One of the most promising breast imaging modalities is microwave imaging. The physical basis of active microwave imaging is the dielectric contrast between normal and malignant breast tissue that exists at microwave frequencies. The dielectric contrast is mainly due to the increased water content present in the cancerous tissue. Microwave imaging is non-ionizing, does not require breast compression, is less invasive than X-ray mammography, and is potentially low cost. While several prototype microwave breast imaging systems are currently in various stages of development, the design and fabrication of anatomically and dielectrically representative breast phantoms to evaluate these systems is often problematic. While some existing phantoms are composed of dielectrically representative materials, they rarely accurately represent the shape and size of a typical breast. Conversely, several phantoms have been developed to accurately model the shape of the human breast, but have inappropriate dielectric properties. This study will brie y review existing phantoms before describing the development of a more accurate and practical breast phantom for the evaluation of microwave breast imaging systems.

  20. A capillary-based perfusion phantom for simulation of brain perfusion for MRI

    International Nuclear Information System (INIS)

    Maciak, A.; Kronfeld, A.; Mueller-Forell, W.; Wille, C.; Kempski, O.; Stoeter, P.

    2010-01-01

    Purpose: The measurement of the CBF is a non-standardized procedure and there are no reliable gold standards. This abstract shows a capillary-based perfusion-phantom for CE-DSC-MRI. It has equivalent flow properties to those within the tissue capillary system of the human brain and allows the validation of the Siemens Perfusion (MR) software. Materials and Methods: The perfusion phantom consists of a dialyzer for the simulation of the capillary system, a feeding tube for simulation of the AIF and a pulsatile pump for simulation of the heart. Using this perfusion phantom, the exact determination of the gold standard CBF due to the well-known geometry of the phantom is easy. It was validated based on different perfusion measurements. These measurements were investigated with standard software (Siemens Perfusion MR). The software determined the CBF within the capillary system. Based on this CBF, a comparison to the gold standard was made with several different flow speeds. After AIF selection, a total of 726 CBF data points were automatically extracted by the software. Results: This results in a comparison of the gold standard CBF to these 726 CBF values. Therefore, a reproducible and reliable deviation estimation between gold standard CBF and measured CBF using the software was computed. It can be shown that the deviation between gold standard and software-based evaluation ranges between 1 and 31 %. Conclusion: There is no significance for any correlation between flow speed and amount of deviation. The mean measured CBF is 11.4 % higher than the gold standard CBF (p-value < 0.001). Using this kind of perfusion-phantom, the validation of different software systems allows reliable conclusions about their quality. (orig.)

  1. Developing a mailed phantom to implement a local QA program in Egypt radiotherapy centers

    Science.gov (United States)

    Soliman, H. A.; Aletreby, M.

    2016-07-01

    In this work, a simple method that differs from the IAEA/WHO Thermoluminescent dosimeters (TLD) postal quality assurance (QA) program is developed. A small perspex; polymethyl methacrylate (PMMA), phantom measured 50 mm × 50 mm × 50 mm is constructed to be used for absorbed dose verification of high-energy photon beams in some major radiotherapy centers in Egypt. The phantom weighted only 140.7 g with two buildup covers weighted 14.8 and 43.19 g for the Cobalt-60 and the 6-MV X-ray beams, respectively. This phantom is aimed for use in the future's external audit/QA services in Egypt for the first time. TLD-700 chips are used for testing and investigating a convenient and national dosimetry QA program. Although the used methodology is comparable to previously introduced but new system; it has smaller size, less weight, and different more available material. Comparison with the previous similar designs is introduced. Theoretical calculations were done by the commercial Eclipse treatment planning system, implementing the pencil beam convolution algorithm to verify the accuracy of the experimental calculation of the dose conversion factor of water to the perspex phantom. The new constructed small phantom and methodology was applied in 10 participating radiotherapy centers. The absorbed dose was verified under the reference conditions for both 60Co and 6-MV high-energy photon beams. The checked beams were within the 5% limit except for four photon beams. There was an agreement of 0.2% between our experimental data and those previously published confirming the validity of the applied method in verifying radiotherapy absorbed dose.

  2. TU-G-BRD-05: Results From Multi-Institutional Measurements with An Anthropomorphic Spine Phantom

    International Nuclear Information System (INIS)

    Molineu, A; Hernandez, N; Alvarez, P; Followill, D

    2015-01-01

    Purpose: To analyze the results from an anthropomorphic spine phantom used for credentialing institutions for National Cancer Institute (NCI) sponsored clinical trial. Methods: An anthropomorphic phantom that contains left and right lungs, a heart, an esophagus, spinal cord, bony material and a PTV was sent to institutions wishing to be credentialed for NCI trials. The PTV holds 4 TLD and radiochromic film in the axial and sagittal planes. The heart holds one TLD. Institutions created IMRT plans to cover ≥90% of the PTV with 6 Gy and limit the cord dose to <0.35cc receiving 3.75 Gy and <1.2cc receiving 2.63 Gy. They were instructed to treat the phantom as they would a patient, including making plan specific IMRT/SBRT QA measurements before treatment. The TLD results in the PTV were required to be within ±7% of the plan dose. A gamma calculation was performed using the film results and the submitted DICOM plan. ≥85% of the analyzed region was required to pass a 5%/3 mm criteria. Results: 176 institutions irradiated the spine phantom for a total of 255 results. The pass rate was 73% (187 irradiations) overall. 44 irradiations failed only the gamma criteria, 2 failed only the dose criteria and 22 failed both. The most used planning systems were Eclipse (116) and Pinnacle (52) and they had pass rates of 76% and 71%, respectively. The AAA algorithm had a pass rate of 77% while superposition type algorithms had a 71% pass rate. The average TLD measurement to institution calculation ratio was 0.99 (0.04 std dev.). The average percent pixels passing the gamma criteria for films was 89% (12% std dev.) Conclusion: Results show that this phantom is an important part of credentialing and that we have room for improvement in IMRT/SBRT spine treatments. This work was supported by PHS CA180803 and CA037422 awarded by NCI, DHHS

  3. Benchmark calculations with simple phantom for neutron dosimetry (2)

    International Nuclear Information System (INIS)

    Yukio, Sakamoto; Shuichi, Tsuda; Tatsuhiko, Sato; Nobuaki, Yoshizawa; Hideo, Hirayama

    2004-01-01

    Benchmark calculations for high-energy neutron dosimetry were undertaken after SATIF-5. Energy deposition in a cylindrical phantom with 100 cm radius and 30 cm depth was calculated for the irradiation of neutrons from 100 MeV to 10 GeV. Using the ICRU four-element loft tissue phantom and four single-element (hydrogen, carbon, nitrogen and oxygen) phantoms, the depth distributions of deposition energy and those total at the central region of phantoms within l cm radius and at the whole region of phantoms within 100 cm radius were calculated. The calculated results of FLUKA, MCNPX, MARS, HETC-3STEP and NMTC/JAM codes were compared. It was found that FLUKA, MARS and NMTC/JAM showed almost the same results. For the high-energy neutron incident, the MCNP-X results showed the largest ones in the total deposition energy and the HETC-3STEP results show'ed smallest ones. (author)

  4. Simplified spinal cord phantom for evaluation of SQUID magnetospinography

    International Nuclear Information System (INIS)

    Adachi, Y; Oyama, D; Uehara, G; Somchai, N; Kawabata, S

    2014-01-01

    Spinal cord functional imaging by magnetospinography (MSG) is a noninvasive diagnostic method for spinal cord diseases. However, the accuracy and spatial resolution of lesion localization by MSG have barely been evaluated in detail so far. We developed a simplified spinal cord phantom for MSG evaluation. The spinal cord phantom is composed of a cylindrical vessel filled with saline water, which acts as a model of a neck. A set of modeled vertebrae is arranged in the cylindrical vessel, which has a neural current model made from catheter electrodes. The neural current model emulates the current distribution around the activated site along the axon of the spinal cord nerve. Our MSG system was used to observe the magnetic field from the phantom; a quadrupole-like pattern of the magnetic field distribution, which is a typical distribution pattern for spinal cord magnetic fields, was successfully reproduced by the phantom. Hence, the developed spinal cord phantom can be used to evaluate MSG source analysis methods.

  5. Construction of cardiac anthropomorphic phantom for simulation of radiological exams

    International Nuclear Information System (INIS)

    Bandeira, C.K.; Vieira Neto, H.; Vieira, M.P.M.M.

    2017-01-01

    Phantoms are simulating objects of structures of the human body and can be applied in the quality control and calibration of radiological equipment. The aim of the work is the development of a cardiac anthropomorphic phantom to assist in the elaboration of protocols of dynamic studies that demonstrate the blood circulation inside the cardiac chambers. For the construction of the phantom was used latex, applied in layers on an anatomical model of heart, having been constructed the cardiac chambers and atrioventricular valves. Cardiac chambers were connected to the cannulas for fluid injection and simulation of the circulatory system. The constructed phantom presents anthropomorphic characteristics and allows the circulation of the fluid without reflux, but the thickness of the catheters used does not yet allow flows of greater order of magnitude. This phantom has the potential to be used in the dynamic simulation of cardiac exams, contributing to the elaboration and adequacy of computed tomography protocols

  6. Assembling of a phantom for quality control in pediatric radiodiagnosis

    International Nuclear Information System (INIS)

    Oliveira, Silvana Carvalho de; Ghilardi Netto, Thomaz; Trad, Clovis Simao; Brochi, Marco Aurelio Corte; Rocha, Sergio Luis

    1996-01-01

    The adaptation of an homogeneous phantom equivalent to an adult patient is presented for the valuation of pediatric radiologic images. The phantom consists basically of two plastic (methyl methacrylate) slabs, each 2.5 cm tick and two aluminium slabs, 0.5 and 1.0 mm thick. The system can simulate the chest, the skull or pelvis, and the extremities. The phantom also enables the equipment calibration, in order to reach the best radiographic image. After calibration of the equipment for several kVp and m As combinations, a phantom with known details and equivalent thickness was used to produce images. These radiographs allowed the choice of the best combination to be used. The entrance surface doses are presented for several combinations used with the pelvis and chest phantoms

  7. Monte Carlo Simulations for Homeland Security Using Anthropomorphic Phantoms

    International Nuclear Information System (INIS)

    Burns, Kimberly A.

    2008-01-01

    A radiological dispersion device (RDD) is a device which deliberately releases radioactive material for the purpose of causing terror or harm. In the event that a dirty bomb is detonated, there may be airborne radioactive material that can be inhaled as well as settle on an individuals leading to external contamination. Monte Carlo calculations were performed to simulate healthcare workers in the operating room or trauma room at a hospital. The Monte Carlo Neutral Particle transport code MCNP5 was used for the modeling. The human body was modeled using Medical Internal Radiation Dose (MIRD-V) anthropomorphic phantoms originally developed at Oak Ridge National Laboratory (ORNL) under the specifications of International Commission on Radiation Protection (ICRP) Publication 23 and later altered at Georgia Tech (17). This study considered two possible contamination scenarios: uniform external contamination with no internal contamination and inhaled radioactive material without any external contamination. For both scenarios, the patients isotopes considered were 60 Co, 137 Cs, 131 I, 192 Ir, and 241 Am. For the externally contaminated patient, a uniform volume source two millimeters thick was placed around the skin of each anthropomorphic phantom to simulate a uniform source on the surface of the body. For the internally contaminated patients, the Dose and Risk Calculation software, DCAL, was used to determine the distribution of the isotopes in the internal organs. For both of the scenarios, the healthcare provider was placed 20-cm from the middle of the torso of the contaminated patient. The amount of energy deposited to the tissues and organs of the healthcare provider due to the internally and externally contaminated patients and in the patient in the case of external contamination was determined. The effective dose rate was calculated using the masses of the tissues and organ and tissue weighting factors from ICRP Publication 60. The effective dose rate for the

  8. Quantitative magnetic resonance imaging phantoms: A review and the need for a system phantom.

    Science.gov (United States)

    Keenan, Kathryn E; Ainslie, Maureen; Barker, Alex J; Boss, Michael A; Cecil, Kim M; Charles, Cecil; Chenevert, Thomas L; Clarke, Larry; Evelhoch, Jeffrey L; Finn, Paul; Gembris, Daniel; Gunter, Jeffrey L; Hill, Derek L G; Jack, Clifford R; Jackson, Edward F; Liu, Guoying; Russek, Stephen E; Sharma, Samir D; Steckner, Michael; Stupic, Karl F; Trzasko, Joshua D; Yuan, Chun; Zheng, Jie

    2018-01-01

    The MRI community is using quantitative mapping techniques to complement qualitative imaging. For quantitative imaging to reach its full potential, it is necessary to analyze measurements across systems and longitudinally. Clinical use of quantitative imaging can be facilitated through adoption and use of a standard system phantom, a calibration/standard reference object, to assess the performance of an MRI machine. The International Society of Magnetic Resonance in Medicine AdHoc Committee on Standards for Quantitative Magnetic Resonance was established in February 2007 to facilitate the expansion of MRI as a mainstream modality for multi-institutional measurements, including, among other things, multicenter trials. The goal of the Standards for Quantitative Magnetic Resonance committee was to provide a framework to ensure that quantitative measures derived from MR data are comparable over time, between subjects, between sites, and between vendors. This paper, written by members of the Standards for Quantitative Magnetic Resonance committee, reviews standardization attempts and then details the need, requirements, and implementation plan for a standard system phantom for quantitative MRI. In addition, application-specific phantoms and implementation of quantitative MRI are reviewed. Magn Reson Med 79:48-61, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  9. SU-F-I-59: Quality Assurance Phantom for PET/CT Alignment and Attenuation Correction

    International Nuclear Information System (INIS)

    Lin, T; Hamacher, K

    2016-01-01

    Purpose: This study utilizes a commercial PET/CT phantom to investigate two specific properties of a PET/CT system: the alignment accuracy of PET images with those from CT used for attenuation correction and the accuracy of this correction in PET images. Methods: A commercial PET/CT phantom consisting of three aluminum rods, two long central cylinders containing uniform activity, and attenuating materials such as air, water, bone and iodine contrast was scanned using a standard PET/CT protocol. Images reconstructed with 2 mm slice thickness and a 512 by 512 matrix were obtained. The center of each aluminum rod in the PET and CT images was compared to evaluate alignment accuracy. ROIs were drawn on transaxial images of the central rods at each section of attenuating material to determine the corrected activity (in BQML). BQML values were graphed as a function of slice number to provide a visual representation of the attenuation-correction throughout the whole phantom. Results: Alignment accuracy is high between the PET and CT images. The maximum deviation between the two in the axial plane is less than 1.5 mm, which is less than the width of a single pixel. BQML values measured along different sections of the large central rods are similar among the different attenuating materials except iodine contrast. Deviation of BQML values in the air and bone sections from the water section is less than 1%. Conclusion: Accurate alignment of PET and CT images is critical to ensure proper calculation and application of CT-based attenuation correction. This study presents a simple and quick method to evaluate the two with a single acquisition. As the phantom also includes spheres of increasing diameter, this could serve as a straightforward means to annually evaluate the status of a modern PET/CT system.

  10. SU-F-I-59: Quality Assurance Phantom for PET/CT Alignment and Attenuation Correction

    Energy Technology Data Exchange (ETDEWEB)

    Lin, T; Hamacher, K [Columbia University Medical Center, New York, NY (United States)

    2016-06-15

    Purpose: This study utilizes a commercial PET/CT phantom to investigate two specific properties of a PET/CT system: the alignment accuracy of PET images with those from CT used for attenuation correction and the accuracy of this correction in PET images. Methods: A commercial PET/CT phantom consisting of three aluminum rods, two long central cylinders containing uniform activity, and attenuating materials such as air, water, bone and iodine contrast was scanned using a standard PET/CT protocol. Images reconstructed with 2 mm slice thickness and a 512 by 512 matrix were obtained. The center of each aluminum rod in the PET and CT images was compared to evaluate alignment accuracy. ROIs were drawn on transaxial images of the central rods at each section of attenuating material to determine the corrected activity (in BQML). BQML values were graphed as a function of slice number to provide a visual representation of the attenuation-correction throughout the whole phantom. Results: Alignment accuracy is high between the PET and CT images. The maximum deviation between the two in the axial plane is less than 1.5 mm, which is less than the width of a single pixel. BQML values measured along different sections of the large central rods are similar among the different attenuating materials except iodine contrast. Deviation of BQML values in the air and bone sections from the water section is less than 1%. Conclusion: Accurate alignment of PET and CT images is critical to ensure proper calculation and application of CT-based attenuation correction. This study presents a simple and quick method to evaluate the two with a single acquisition. As the phantom also includes spheres of increasing diameter, this could serve as a straightforward means to annually evaluate the status of a modern PET/CT system.

  11. Construction of average adult Japanese voxel phantoms for dose assessment

    International Nuclear Information System (INIS)

    Sato, Kaoru; Takahashi, Fumiaki; Satoh, Daiki; Endo, Akira

    2011-12-01

    The International Commission on Radiological Protection (ICRP) adopted the adult reference voxel phantoms based on the physiological and anatomical reference data of Caucasian on October, 2007. The organs and tissues of these phantoms were segmented on the basis of ICRP Publication 103. In future, the dose coefficients for internal dose and dose conversion coefficients for external dose calculated using the adult reference voxel phantoms will be widely used for the radiation protection fields. On the other hand, the body sizes and organ masses of adult Japanese are generally smaller than those of adult Caucasian. In addition, there are some cases that the anatomical characteristics such as body sizes, organ masses and postures of subjects influence the organ doses in dose assessment for medical treatments and radiation accident. Therefore, it was needed to use human phantoms with average anatomical characteristics of Japanese. The authors constructed the averaged adult Japanese male and female voxel phantoms by modifying the previously developed high-resolution adult male (JM) and female (JF) voxel phantoms. It has been modified in the following three aspects: (1) The heights and weights were agreed with the Japanese averages; (2) The masses of organs and tissues were adjusted to the Japanese averages within 10%; (3) The organs and tissues, which were newly added for evaluation of the effective dose in ICRP Publication 103, were modeled. In this study, the organ masses, distances between organs, specific absorbed fractions (SAFs) and dose conversion coefficients of these phantoms were compared with those evaluated using the ICRP adult reference voxel phantoms. This report provides valuable information on the anatomical and dosimetric characteristics of the averaged adult Japanese male and female voxel phantoms developed as reference phantoms of adult Japanese. (author)

  12. Characterization of paraffin based breast tissue equivalent phantom using a CdTe detector pulse height analysis.

    Science.gov (United States)

    Cubukcu, Solen; Yücel, Haluk

    2016-12-01

    In this study, paraffin was selected as a base material and mixed with different amounts of CaSO 4 ·2H 2 O and H 3 BO 3 compounds in order to mimic breast tissue. Slab phantoms were produced with suitable mixture ratios of the additives in the melted paraffin. Subsequently, these were characterized in terms of first half-value layer (HVL) in the mammographic X-ray range using a pulse-height spectroscopic analysis with a CdTe detector. Irradiations were performed in the energy range of 23-35 kV p under broad beam conditions from Mo/Mo and Mo/Rh target/filter combinations. X-ray spectra were acquired with a CdTe detector without and with phantom material interposition in increments of 1 cm thickness and then evaluated to obtain the transmission data. The net integral areas of the spectra for the slabs were used to plot the transmission curves and these curves were fitted to the Archer model function. The results obtained for the slabs were compared with those of standard mammographic phantoms such as CIRS BR series phantoms and polymethylmethacrylate plates (PMMA). From the evaluated transmission curves, the mass attenuation coefficients and HVLs of some mixtures are close to those of the commercially available standard mammography phantoms. Results indicated that when a suitable proportion of H 3 BO 3 and CaSO 4 ·2H 2 O is added to the paraffin, the resulting material may be a good candidate for a breast tissue equivalent phantom.

  13. Measurement of dose distribution in the spherical phantom onboard the ISS-KIBO module -MATROSHKA-R in KIBO-

    Science.gov (United States)

    Kodaira, Satoshi; Kawashima, Hajime; Kurano, Mieko; Uchihori, Yukio; Nikolaev, Igor; Ambrozova, Iva; Kitamura, Hisashi; Kartsev, Ivan; Tolochek, Raisa; Shurshakov, Vyacheslav

    The measurement of dose equivalent and effective dose during manned space missions on the International Space Station (ISS) is important for evaluating the risk to astronaut health and safety when exposed to space radiation. The dosimetric quantities are constantly changing and strongly depend on the level of solar activity and the various spacecraft- and orbit-dependent parameters such as the shielding distribution in the ISS module, location of the spacecraft within its orbit relative to the Earth, the attitude (orientation) and altitude. Consequently, the continuous monitoring of dosimetric quantities is required to record and evaluate the personal radiation dose for crew members during spaceflight. The dose distributions in the phantom body and on its surface give crucial information to estimate the dose equivalent in the human body and effective dose in manned space mission. We have measured the absorbed dose and dose equivalent rates using passive dosimeters installed in the spherical phantom in Japanese Experiment Module (“KIBO”) of the ISS in the framework of Matroshka-R space experiment. The exposure duration was 114 days from May 21 to September 12, 2012. The phantom consists of tissue-equivalent material covered with a poncho jacket with 32 pockets on its surface and 20 container rods inside of the phantom. The phantom diameter is 35 cm and the mass is 32 kg. The passive dosimeters consisted of a combination of luminescent detectors of Al _{2}O _{3};C OSL and CaSO _{4}:Dy TLD and CR-39 plastic nuclear track detectors. As one of preliminary results, the dose distribution on the phantom surface measured with OSL detectors installed in the jacket pockets is found to be ranging from 340 muGy/day to 260 muGy/day. In this talk, we will present the detail dose distributions, and variations of LET spectra and quality factor obtained outside and inside of the spherical phantom installed in the ISS-KIBO.

  14. An open source, 3D printed preclinical MRI phantom for repeated measures of contrast agents and reference standards.

    Science.gov (United States)

    Cox, B L; Ludwig, K D; Adamson, E B; Eliceiri, K W; Fain, S B

    2018-03-01

    In medical imaging, clinicians, researchers and technicians have begun to use 3D printing to create specialized phantoms to replace commercial ones due to their customizable and iterative nature. Presented here is the design of a 3D printed open source, reusable magnetic resonance imaging (MRI) phantom, capable of flood-filling, with removable samples for measurements of contrast agent solutions and reference standards, and for use in evaluating acquisition techniques and image reconstruction performance. The phantom was designed using SolidWorks, a computer-aided design software package. The phantom consists of custom and off-the-shelf parts and incorporates an air hole and Luer Lock system to aid in flood filling, a marker for orientation of samples in the filled mode and bolt and tube holes for assembly. The cost of construction for all materials is under $90. All design files are open-source and available for download. To demonstrate utility, B 0 field mapping was performed using a series of gadolinium concentrations in both the unfilled and flood-filled mode. An excellent linear agreement (R 2 >0.998) was observed between measured relaxation rates (R 1 /R 2 ) and gadolinium concentration. The phantom provides a reliable setup to test data acquisition and reconstruction methods and verify physical alignment in alternative nuclei MRI techniques (e.g. carbon-13 and fluorine-19 MRI). A cost-effective, open-source MRI phantom design for repeated quantitative measurement of contrast agents and reference standards in preclinical research is presented. Specifically, the work is an example of how the emerging technology of 3D printing improves flexibility and access for custom phantom design.

  15. A quantitative experimental phantom study on MRI image uniformity.

    Science.gov (United States)

    Felemban, Doaa; Verdonschot, Rinus G; Iwamoto, Yuri; Uchiyama, Yuka; Kakimoto, Naoya; Kreiborg, Sven; Murakami, Shumei

    2018-05-02

    Our goal was to assess MR image uniformity by investigating aspects influencing said uniformity via a method laid out by the National Electrical Manufacturers Association (NEMA). Six metallic materials embedded in a glass phantom were scanned (i.e., Au, Ag, Al, Au-Ag-Pd alloy, Ti and Co-Cr alloy) as well as a reference image. Sequences included Spin Echo (SE) and gradient echo (GRE) scanned in three planes (i.e., Axial, Coronal, and Sagittal). Moreover, three surface coil types (i.e., Head and Neck or HN, Brain, and TMJ coils) and two image correction methods (i.e., Surface Coil Intensity Correction or SCIC, Phased array Uniformity Enhancement or PURE) were employed to evaluate their effectiveness on image uniformity. Image uniformity was assessed using the NEMA peak-deviation non-uniformity method. Results showed that TMJ coils elicited the least uniform image and Brain coils outperformed HN coils when metallic materials were present. Additionally, when metallic materials were present, SE outperformed GRE especially for Co-Cr (particularly in the axial plane). Furthermore, both SCIC and PURE improved image uniformity compared to uncorrected images, and SCIC slightly surpassed PURE when metallic metals were present. Lastly, Co-Cr elicited the least uniform image while other metallic materials generally showed similar patterns (i.e., no significant deviation from images without metallic metals). Overall, a quantitative understanding of the factors influencing MR image uniformity (e.g., coil type, imaging method, metal susceptibility, and post-hoc correction method) is advantageous to optimize image quality, assists clinical interpretation, and may result in improved medical and dental care.

  16. Optimization of a novel large field of view distortion phantom for MR-only treatment planning.

    Science.gov (United States)

    Price, Ryan G; Knight, Robert A; Hwang, Ken-Pin; Bayram, Ersin; Nejad-Davarani, Siamak P; Glide-Hurst, Carri K

    2017-07-01

    MR-only treatment planning requires images of high geometric fidelity, particularly for large fields of view (FOV). However, the availability of large FOV distortion phantoms with analysis software is currently limited. This work sought to optimize a modular distortion phantom to accommodate multiple bore configurations and implement distortion characterization in a widely implementable solution. To determine candidate materials, 1.0 T MR and CT images were acquired of twelve urethane foam samples of various densities and strengths. Samples were precision-machined to accommodate 6 mm diameter paintballs used as landmarks. Final material candidates were selected by balancing strength, machinability, weight, and cost. Bore sizes and minimum aperture width resulting from couch position were tabulated from the literature (14 systems, 5 vendors). Bore geometry and couch position were simulated using MATLAB to generate machine-specific models to optimize the phantom build. Previously developed software for distortion characterization was modified for several magnet geometries (1.0 T, 1.5 T, 3.0 T), compared against previously published 1.0 T results, and integrated into the 3D Slicer application platform. All foam samples provided sufficient MR image contrast with paintball landmarks. Urethane foam (compressive strength ∼1000 psi, density ~20 lb/ft 3 ) was selected for its accurate machinability and weight characteristics. For smaller bores, a phantom version with the following parameters was used: 15 foam plates, 55 × 55 × 37.5 cm 3 (L×W×H), 5,082 landmarks, and weight ~30 kg. To accommodate > 70 cm wide bores, an extended build used 20 plates spanning 55 × 55 × 50 cm 3 with 7,497 landmarks and weight ~44 kg. Distortion characterization software was implemented as an external module into 3D Slicer's plugin framework and results agreed with the literature. The design and implementation of a modular, extendable distortion phantom was optimized for several bore

  17. Evaluation of image uniformity and radiolucency for computed tomography phantom made of 3-dimensional printing of fused deposition modeling technology by using acrylonitrile but audience styrene resin

    Energy Technology Data Exchange (ETDEWEB)

    Seoung, Youl Hun [Dept. of of Radiological Science, Cheongju University, Cheongju (Korea, Republic of)

    2016-09-15

    The purpose of this study was to evaluate the radiolucency for the phantom output to the 3D printing technology. The 3D printing technology was applied for FDM (fused deposition modeling) method and was used the material of ABS (acrylonitrile butadiene styrene) resin. The phantom was designed in cylindrical uniformity. An image uniformity was measured by a cross-sectional images of the 3D printed phantom obtained from the CT equipment. The evaluation of radiolucency was measured exposure dose by the inserted ion-chamber from the 3D printed phantom. As a results, the average of uniformity in the cross-sectional CT image was 2.70 HU and the correlation of radiolucency between PMMA CT phantom and 3D printed ABS phantom is found to have a high correlation to 0.976. In the future, this results will be expected to be used as the basis for the phantom production of the radiation quality control by used 3D printing technology.

  18. Evaluation of image uniformity and radiolucency for computed tomography phantom made of 3-dimensional printing of fused deposition modeling technology by using acrylonitrile but audience styrene resin

    International Nuclear Information System (INIS)

    Seoung, Youl Hun

    2016-01-01

    The purpose of this study was to evaluate the radiolucency for the phantom output to the 3D printing technology. The 3D printing technology was applied for FDM (fused deposition modeling) method and was used the material of ABS (acrylonitrile butadiene styrene) resin. The phantom was designed in cylindrical uniformity. An image uniformity was measured by a cross-sectional images of the 3D printed phantom obtained from the CT equipment. The evaluation of radiolucency was measured exposure dose by the inserted ion-chamber from the 3D printed phantom. As a results, the average of uniformity in the cross-sectional CT image was 2.70 HU and the correlation of radiolucency between PMMA CT phantom and 3D printed ABS phantom is found to have a high correlation to 0.976. In the future, this results will be expected to be used as the basis for the phantom production of the radiation quality control by used 3D printing technology

  19. Electrical impedance spectroscopy (EIS)-based evaluation of biological tissue phantoms to study multifrequency electrical impedance tomography (Mf-EIT) systems

    KAUST Repository

    Bera, Tushar Kanti

    2016-03-18

    Abstract: Electrical impedance tomography (EIT) phantoms are essential for the calibration, comparison and evaluation of the EIT systems. In EIT, the practical phantoms are typically developed based on inhomogeneities surrounded by a homogeneous background to simulate a suitable conductivity contrast. In multifrequency EIT (Mf-EIT) evaluation, the phantoms must be developed with the materials which have recognizable or distinguishable impedance variations over a wide range of frequencies. In this direction the impedance responses of the saline solution (background) and a number vegetable and fruit tissues (inhomogeneities) are studied with electrical impedance spectroscopy (EIS) and the frequency responses of bioelectrical impedance and conductivity are analyzed. A number of practical phantoms with different tissue inhomogeneities and different inhomogeneity configurations are developed and the multifrequency impedance imaging is studied with the Mf-EIT system to evaluate the phantoms. The conductivity of the vegetable inhomogeneities reconstructed from the EIT imaging is compared with the conductivity values obtained from the EIS studies. Experimental results obtained from multifrequency EIT reconstruction demonstrate that the electrical impedance of all the biological tissues inhomogenity decreases with frequency. The potato tissue phantom produces better impedance image in high frequency ranges compared to the cucumber phantom, because the cucumber impedance at high frequency becomes lesser than that of the potato at the same frequency range. Graphical Abstract: [Figure not available: see fulltext.] © 2016 The Visualization Society of Japan

  20. Application of Electron Dose Kernels to account for heterogeneities in voxelized phantoms

    International Nuclear Information System (INIS)

    Al-Basheer, A. K.; Sjoden, G. E.; Ghita, M.; Bolch, W.

    2009-01-01

    In this paper, we present work on the application of the Electron Dose Kernel discrete ordinates method (EDK-S N ) to compute doses and account for material heterogeneities using high energy external photon beam irradiations in voxelized human phantoms. EDKs are pre-computed using photon pencil 'beamlets' that lead to dose delivery in tissue using highly converged Monte Carlo. Coupling the EDKs to accumulate dose scaled by integral photon fluences computed using S N methods in dose driving voxels (DDVs) allows for the full charged particle physics computed dose to be accumulated throughout the voxelized phantom, and is the basis of the EDK-S N method, which is fully parallelized. For material heterogeneities, a density scaling correction factor is required to yield good agreement. In a fully voxelized phantom, all doses were in agreement with those determined by independent Monte Carlo computations. We are continuing to expand upon the development of this robust approach for rapid and accurate determination of whole body and out of field organ doses due to high energy x-ray beams. (authors)

  1. Study on quantities of radiation protection in medical X-rays radiation field with polyhedron phantom

    International Nuclear Information System (INIS)

    Yuan Shuyu; Dai Guangfu; Zhang Liangan

    1997-01-01

    The author have studied tissue-equivalent material with the elemental composition recommended by report No.44 of ICRU. Three different calibration phantoms in shape have been prepared with the tissue-equivalent material in order to study the influence of the angular dependence factor R(d,α) in the radiation field of X-rays on the calibration of individual dose equivalent Hp(d). The requirement of mono-genous radiation field to calibrate several dosimeters on one phantom at the same time can be met by application of dodecahedron phantom, which is difficult on ICRU sphere. Angular dependence factor R(d,α) of 0 degree∼90 degree and conversion coefficients between individual dose equivalent Hp(0.07, α) and the exposure of radiation of different energies and different angles have been established by taking advantage of the dodecahedron. Besides, the authors have studied the variation relation between the individual dose equivalent Hp (10,α) and Hp(0.07,α) in the medical X-rays radiation field

  2. Development of a voxel phantom specific for simulation of eye brachytherapy

    International Nuclear Information System (INIS)

    Santos, Marcilio S.; Lima, Fernando R.A.

    2013-01-01

    The ophthalmic brachytherapy involves inserting a plate with seeds of radioactive material in the patient's eye for the treatment of tumors. The radiation dose to be taken by the patient is prescribed by physicians and time of application of the material is calculated from calibration curves supplied by the manufacturers of the plates. To estimate the dose absorbed by the patient, in a series of diagnostic tests, it is necessary to perform simulations using a computational model of exposure. These models are composed primarily by a anthropomorphic phantom, and a Monte Carlo code. The coupling of a phantom voxel whole body to a Monte Carlo code is a complex process because the computer model simulations with exposure takes time, knowledge of the code used and various adjustments to be implemented. The problem is aggravated even more complex when you want to radiate one region of the body. In this work we developed a phantom, specifically the region containing the eyeball, from MASH (Male Adult voxel). This model was coupled to the Monte Carlo code EGSnrc (Electron Gamma Shower) together with an algorithm simulator source of I-125 , considering only its effect of higher energy range

  3. Monte Carlo simulation of a stand-up type whole body counter using different sized BOMAB phantoms

    International Nuclear Information System (INIS)

    Park, Minjung; Yoo, Jaeryong; Park, Seyoung; Ha, Wiho; Lee, Seungsook; Park, Minjung; Yoo, Jaeryong; Kim, Kwangpyo

    2013-01-01

    It is necessary to assess internal contamination level to determine the need for medical intervention. Whole Body Counter (WBC) is used to measure incorporated radioactive materials inside the human body. Also, WBC is standard in vivo method and used for preparedness of response to radiological emergencies. To operate this equipment correctly, proper energy and efficiency calibrations must be performed. WBC is usually calibrated using a Bottle Manikin ABsorber (BOMAB) Phantom, which is the industrial standard. The problem occurs when the subjects to be measured have different physical characteristics (height or weight) from a phantom used in calibration. In radiation emergency situations, this problem is expected to worsen because there are special populations whose physical characteristics are different from reference male, for example children and women. The aim of this study is to resolve this problem by simulating counting efficiency of different sized BOMAB phantoms using Monte Carlo techniques. The counting efficiency response of the WBC has been modeled for different sized four BOMAB phantoms using MCNPX. The stand-up type WBC has different efficiency response on phantom size since this WBC has different geometry from other scanning-type or non-linear geometry WBC. In emergency monitoring situations, it is important to estimate activity of various sized persons. Therefore, it is necessary to apply appropriate counting efficiency according to person size. Further investigations are needed to optimize methodology for measuring small object in the stand-up type WBC

  4. A new test phantom with different breast tissue compositions for image quality assessment in conventional and digital mammography

    International Nuclear Information System (INIS)

    Pachoud, Marc; Lepori, D; Valley, Jean-Francois; Verdun, Francis R

    2004-01-01

    Our objective is to describe a new test phantom that permits the objective assessment of image quality in conventional and digital mammography for different types of breast tissue. A test phantom, designed to represent a compressed breast, was made from tissue equivalent materials. Three separate regions, with different breast tissue compositions, are used to evaluate low and high contrast resolution, spatial resolution and image noise. The phantom was imaged over a range of kV using a Contour 2000 (Bennett) mammography unit with a Kodak MinR 2190-MinR L screen-film combination and a Senograph 2000D (General Electric) digital mammography unit. Objective image quality assessments for different breast tissue compositions were performed using the phantom for conventional and digital mammography. For a similar mean glandular dose (MGD), the digital system gives a significantly higher contrast-to-noise ratio (CNR) than the screen-film system for 100% glandular tissue. In conclusion, in mammography, a range of exposure conditions is used for imaging because of the different breast tissue compositions encountered clinically. Ideally, the patient dose-image quality relationship should be optimized over the range of exposure conditions. The test phantom presented in this work permits image quality parameters to be evaluated objectively for three different types of breast tissue. Thus, it is a useful tool for optimizing the patient dose-image quality relationship

  5. Calculation of dose distribution for 252Cf fission neutron source in tissue equivalent phantoms using Monte Carlo method

    International Nuclear Information System (INIS)

    Ji Gang; Guo Yong; Luo Yisheng; Zhang Wenzhong

    2001-01-01

    Objective: To provide useful parameters for neutron radiotherapy, the author presents results of a Monte Carlo simulation study investigating the dosimetric characteristics of linear 252 Cf fission neutron sources. Methods: A 252 Cf fission source and tissue equivalent phantom were modeled. The dose of neutron and gamma radiations were calculated using Monte Carlo Code. Results: The dose of neutron and gamma at several positions for 252 Cf in the phantom made of equivalent materials to water, blood, muscle, skin, bone and lung were calculated. Conclusion: The results by Monte Carlo methods were compared with the data by measurement and references. According to the calculation, the method using water phantom to simulate local tissues such as muscle, blood and skin is reasonable for the calculation and measurements of dose distribution for 252 Cf

  6. Computation of a voxelized anthropomorphic phantom from Computer Tomography slices and 3D dose distribution calculation utilizing the MCNP5 Code

    International Nuclear Information System (INIS)

    Abella, V.; Miro, R.; Juste, B.; Verdu, G.

    2008-01-01

    Full text: The purpose of this work is to obtain the voxelization of a series of tomography slices in order to provide a voxelized human phantom throughout a MatLab algorithm, and the consequent simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) 60 Co radiotherapy unit, using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project provides as results dose mapping calculations inside the voxelized anthropomorphic phantom. Prior works have validated the cobalt therapy model utilizing a simple heterogeneous water cube-shaped phantom. The reference phantom model utilized in this work is the Zubal phantom, which consists of a group of pre-segmented CT slices of a human body. The CT slices are to be input into the Matlab program which computes the voxelization by means of two-dimensional pixel and material identification on each slice, and three-dimensional interpolation, in order to depict the phantom geometry via small cubic cells. Each slice is divided in squares with the size of the desired voxelization, and then the program searches for the pixel intensity with a predefined material at each square, making a subsequent three-dimensional interpolation. At the end of this process, the program produces a voxelized phantom in which each voxel defines the mixture of the different materials that compose it. In the case of the Zubal phantom, the voxels result in pure organ materials due to the fact that the phantom is presegmented. The output of this code follows the MCNP input deck format and is integrated in a full input model including the 60 Co radiotherapy unit. Dose rates are calculated using the MCNP5 tool FMESH, superimposed mesh tally. This feature allows to tally particles on an independent mesh over the problem geometry, and to obtain the length estimation of the particle flux, in units of particles/cm 2 (tally F4). Furthermore, the particle flux is transformed into dose by

  7. Hubungan Phantom Vibration Syndrome Terhadap Sleep Disorder dan Kondisi Stress

    Directory of Open Access Journals (Sweden)

    Ajeng Yeni Setianingrum

    2017-10-01

    Full Text Available Phantom vibration syndrome is a condition where a person would feel the sensation of vibration of a cell phone as if there were incoming notification but the fact is not. This research investigated the relationship between phantom vibration syndromes, sleep disorder and stress condition. Questionnaires were distributed to 120 participants with age range 18 to 23 years old. Data of participants showed that all of participants using a smart mobile phone and 24% of them have more than one cell phone. Time usage of cell phone is at least 1 hour. 23% of participants using a cell phone for social media activity, followed by 21% related to entertainment (music, video and games. The results showed a positive relationship between phantom vibration syndrome, sleep disorder and stress condition. Insomnia contributed a greater influence on stress condition. However, the phantom vibration syndrome is more directly affecting the sleep apnea compared to insomnia and stress condition. Therefore, the phantom vibration syndrome more affects stress condition indirectly, through sleep disorder (sleep apnea and insomnia. Consequently, phantom vibration syndrome has a strong relationship with stress condition at the time of the phantom vibration syndrome can cause sleep disorder.

  8. Studies on Phantom Vibration and Ringing Syndrome among Postgraduate Students

    Directory of Open Access Journals (Sweden)

    Atul Kumar Goyal

    2015-03-01

    Full Text Available Phantom vibrations and ringing of mobile phones are prevalent hallucinations in the general population. They might be considered as a normal brain mechanism. The aim of this study was to establish the prevalence of Phantom vibrations and ringing syndrome among students and to assess factors associated it. The survey of 300 postgraduate students belonging to different field of specialization was conducted at Kurukshetra University. 74% of students were found to have both Phantom vibrations and ringing syndrome. Whereas 17% of students felt Phantom vibration exclusively and 4% students face only Phantom ringing syndrome. Both the syndrome occurs more fervent in students who kept their mobile phone in shirt or jean pocket than to who kept mobile in handbag. 75% of students felt vibration or ringing even when the phone is switched off or phone was not in their pocket. Also the frequency of both the syndrome is directly proportional to the duration of mobile phone use and person emotional behavior. Although most of students agree that the Phantom syndrome did not bother them but some students deals with anxiety when they feel symptoms associated with Phantom syndrome. By using mobile phones in proper way, one can avoid these syndromes, or at least can ameliorate the symptoms.

  9. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-12-01

    The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements-including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth-were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light-tissue interactions and characterizing biophotonic system performance.

  10. Puzzles of dark energy in the Universe—phantom

    International Nuclear Information System (INIS)

    Dabrowski, Mariusz P

    2015-01-01

    This paper is devoted to some simple approach based on general physics tools to describe the physical properties of a hypothetical particle which can be the source of dark energy in the Universe known as phantom. Phantom is characterized by the fact that it possesses negative momentum and kinetic energy and that it gives dominant negative pressure which acts as antigravity. We consider a phantom harmonic oscillator in comparison to a standard harmonic oscillator. By using the first law of thermodynamics we explain why the energy density of the Universe grows when it is filled with phantom. We also show how the collision of phantom with a standard particle leads to extraction of energy from the former by the latter (i.e. from phantom to the standard) if their masses are different. The most striking of our conclusions is that the collision of phantom and standard particles of the same mass is impossible unless both of them are at rest and suddenly start moving with opposite velocities and kinetic energies. This effect is a classic analog of quantum mechanical particle pair creation in a strong electric field or physical vacuum. (paper)

  11. Fabrication of subcutaneous veins phantom for vessel visualization system

    Science.gov (United States)

    Cheng, Kai; Narita, Kazuyuki; Morita, Yusuke; Nakamachi, Eiji; Honda, Norihiro; Awazu, Kunio

    2013-09-01

    The technique of subcutaneous veins imaging by using NIR (Near Infrared Radiation) is widely used in medical applications, such as the intravenous injection and the blood sampling. In the previous study, an automatic 3D blood vessel search and automatic blood sampling system was newly developed. In order to validate this NIR imaging system, we adopted the subcutaneous vein in the human arm and its artificial phantom, which imitate the human fat and blood vessel. The human skin and subcutaneous vein is characterized as the uncertainty object, which has the individual specificity, non-accurate depth information, non-steady state and hardly to be fixed in the examination apparatus. On the other hand, the conventional phantom was quite distinct from the human's characteristics, such as the non-multilayer structure, disagreement of optical property. In this study, we develop a multilayer phantom, which is quite similar with human skin, for improvement of NIR detection system evaluation. The phantom consists of three layers, such as the epidermis layer, the dermis layer and the subcutaneous fat layer. In subcutaneous fat layer, we built a blood vessel. We use the intralipid to imitate the optical scattering characteristics of human skin, and the hemoglobin and melanin for the optical absorption characteristics. In this study, we did two subjects. First, we decide the fabrication process of the phantom. Second, we compared newly developed phantoms with human skin by using our NIR detecting system, and confirm the availability of these phantoms.

  12. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-01-01

    Abstract. The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements—including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth—were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light–tissue interactions and characterizing biophotonic system performance. PMID:26662064

  13. TH-AB-209-12: Tissue Equivalent Phantom with Excised Human Tissue for Assessing Clinical Capabilities of Coherent Scatter Imaging Applications

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, K; Morris, R; Spencer, J [Medical Physics Graduate Program, Duke University, Durham, NC (United States); Greenberg, J [Dept. of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Kapadia, A [Carl E Ravin Advanced Imaging Laboratories, Durham, NC (United States)

    2016-06-15

    Purpose: Previously we reported the development of anthropomorphic tissue-equivalent scatter phantoms of the human breast. Here we present the first results from the scatter imaging of the tissue equivalent breast phantoms for breast cancer diagnosis. Methods: A breast phantom was designed to assess the capability of coded aperture coherent x-ray scatter imaging to classify different types of breast tissue (adipose, fibroglandular, tumor). The phantom geometry was obtained from a prone breast geometry scanned on a dedicated breast CT system. The phantom was 3D printed using the segmented DICOM breast CT data. The 3D breast phantom was filled with lard (as a surrogate for adipose tissue) and scanned in different geometries alongside excised human breast tissues (obtained from lumpectomy and mastectomy procedures). The raw data were reconstructed using a model-based reconstruction algorithm and yielded the location and form factor (i.e., momentum transfer (q) spectrum) of the materials that were imaged. The measured material form factors were then compared to the ground truth measurements acquired by x-ray diffraction (XRD) imaging. Results: Our scatter imaging system was able to define the location and composition of the various materials and tissues within the phantom. Cancerous breast tissue was detected and classified through automated spectral matching and an 86% correlation threshold. The total scan time for the sample was approximately 10 minutes and approaches workflow times for clinical use in intra-operative or other diagnostic tasks. Conclusion: This work demonstrates the first results from an anthropomorphic tissue equivalent scatter phantom to characterize a coherent scatter imaging system. The functionality of the system shows promise in applications such as intra-operative margin detection or virtual biopsy in the diagnosis of breast cancer. Future work includes using additional patient-derived tissues (e.g., human fat), and modeling additional organs

  14. Development and implementation of an anthropomorphic pediatric spine phantom for the assessment of craniospinal irradiation procedures in proton therapy

    Directory of Open Access Journals (Sweden)

    Dana J Lewis

    2014-03-01

    Full Text Available Purpose: To design an anthropomorphic pediatric spine phantom for use in the evaluation of proton therapy facilities for clinical trial participation by the Imaging and Radiation Oncology Core (IROC Houston QA Center (formerly RPC.Methods: This phantom was designed to perform an end-to-end audit of the proton spine treatment process, including simulation, dose calculation by the treatment planning system (TPS, and proton treatment delivery. The design incorporated materials simulating the thoracic spinal column of a pediatric patient, along with two thermoluminescent dosimeter (TLD-100 capsules and radiochromic film embedded in the phantom for dose evaluation. Fourteen potential materials were tested to determine relative proton stopping power (RSP and Hounsfield unit (HU values. Each material was CT scanned at 120 kVp, and the RSP was obtained from depth ionization scans using the Zebra multi-layer ion chamber (MLIC at two energies: 160 MeV and 250 MeV. To determine tissue equivalency, the measured RSP for each material was compared to the RSP calculated by the Eclipse TPS for a given HU.Results: The materials selected as bone, tissue, and cartilage substitutes were Techron HPV Bearing Grade (Boedeker Plastics, Inc., solid water, and blue water, respectively. The RSP values did not differ by more than 1.8% between the two energies. The measured RSP for each selected material agreed with the RSP calculated by the Eclipse TPS within 1.2%.Conclusion: An anthropomorphic pediatric proton spine phantom was designed to evaluate proton therapy delivery. The inclusion of multiple tissue substitutes increases heterogeneity and the level of difficulty for institutions to successfully treat the phantom. The following attributes will be evaluated: absolute dose agreement, distal range, field width, junction match and right/left dose profile alignment. The phantom will be tested at several institutions using a 5% dose agreement criterion, and a 5%/3mm gamma

  15. Neutron production in a spherical phantom aboard ISS

    International Nuclear Information System (INIS)

    Tasbaz, A.; Machrafi, R.

    2012-01-01

    As part of an ongoing research program on radiation monitoring on International Space Station (ISS) that was established to analyze the radiation exposure levels onboard the ISS using different radiation instruments and a spherical phantom to simulate human body. Monte Carlo transport code was used to simulate the interaction of high energy protons and neutrons with the spherical phantom currently onboard ISS. The phantom has been exposed to individual proton energies and to a spectrum of neutrons. The internal to external neutron flux ratio was calculated and compared to the experimental data, recently, measured on the ISS. (author)

  16. Phantom shocks in patients with implantable cardioverter defibrillator

    DEFF Research Database (Denmark)

    Berg, Selina Kikkenborg; Moons, Philip; Zwisler, Ann-Dorthe

    2013-01-01

    of phantom shocks.METHODS AND RESULTS: The design was secondary explorative analyses of data from a randomized controlled trial. One hundred and ninety-six patients with first-time ICD implantation (79% male, mean age 58 years) were randomized (1 : 1) to either combined rehabilitation or a control group...... questions regarding the experience of phantom shocks, date, time, and place. Twelve patients (9.4%) experienced a phantom shock, 7 in the intervention group and 5 in the control group (NS). Neither age, sex, quality of life nor perceived health at baseline was significantly related to the probability...

  17. Water phantom explorer regulated by computer

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, G [Centre Henri Becquerel, 76 - Rouen (France); Sarrau, J M; Bouet, M [ERA CNRS, UER Sciences et Techniques de Rouen, 76 - Mont-Saint-Aignan (France)

    1983-01-01

    A water phantom device is meant to work directly with a Hewlett-Packard 9825 T small computer. The purpose of this work is to read the distribution of absorbed dose released into a perspex container of water with the help of a semiconductor detector which can move in the three dimensions of space. Above the container a second detector situated on the edge of the beam is used as a monitor. The execution of the programmes written in HPL (Hewlett-Packard Language) offers the possibility either to carry out a preprogrammed cycle of displacements and measures or to work in interacting mode. The collected measures (space, co-ordinates and dose measures) are visualized by a plotter and recorded on a cassette tape. The signals delivered by the detectors are amplified separately then a dividing circuit delivers a tension in proportion with the ratio of these two signals. This tension is independent of the dose rate fluctuations of the irradiation beam and can be read by the computer. The examples of study of photon and electron beams that are described hereafter are meant to show the interest of a command that can be programmed.

  18. Segmented phantoms reconstruction for skin dosimetry

    International Nuclear Information System (INIS)

    Antunes, Paula C.G.; Siqueira, Paulo T.D.; Yoriyaz, Helio; Fonseca, Gabriel P.; Furnari, Laura; Reis, Gabriela S.

    2009-01-01

    There are several radio-sensitive skin diseases. Skin dosimetry is a difficult task to be properly performed, not only due to skin extension and small thickness, but also because it is usually submitted to high dose gradients. High-resolution medical images along with methods that simulate the interaction of radiation with matter, as the Monte Carlo radiation transport codes, have been widely used in medical physics procedures. These images provide the construction of realistic computational anatomical models, which after being coupled to these codes, retrieve reliable dosimetric assessments. However, present day regular images are unsuitable to correctly perform skin dose distribution evaluations. This inability is due to improper skin discrimination in most of current medical images, once its thickness stands below image resolution, i.e. pixel characteristic sizes are larger than skin thickness. This paper proposes a methodology of voxelized phantom reconstruction and segmentation, by subdividing their basic elements - voxels. It is done in order to better discriminate the skin by assigning more adequate value for skin thickness and its actual localization. Aiming at a more realistic skin modeling one is expected to get more accurate skin dose evaluations. This task is an important issue in many radiotherapy procedures. A particular interest lays in Total Skin Electron Therapy (TSET), which highlights the treatment of the whole body irradiation, a radiotherapy procedure under implementation in the Hospital das Clinicas da Universidade de Sao Paulo (HC-USP). (author)

  19. Doses mammography: from phantom to the patient

    Energy Technology Data Exchange (ETDEWEB)

    Cross, P [Gammasonic Radiological Services, Pty., Ltd., Five Dock, NSW (Australia)

    1994-02-01

    While the use of a reference phantom is essential for dosimetry in acceptance testing and in regular quality control checks of a mammographic X-ray unit, it is also of importance to be able to estimate the patient dose in each individual investigation. Radiographic and physical data were analysed for a total of 212 women who were screened at three locations participating in a breast screening programme. The radiologists made estimates of the individual breast composition (%glandular/adipose ratio) at the film reporting sessions, and then the glandular doses were calculated by the auditor according to the NCRP 85 methodology. Arising from the data analysis of this dosimetry survey, a method is proposed to determine objectively patient breast composition from the photo-timed mAs for a given film optical density setting. This permits the NCRP calculations to be extended from breasts of 'average' (50/50) composition to breasts of individually determined composition. The diversity of the results between the three locations emphasises the need for regular audits of a mammographic X-ray unit's performance by an experienced radiological physicists, at least annually or after any major interventional service on the unit. 11 refs., 6 tabs., 4 figs.

  20. SU-F-I-37: How Fat Distribution and Table Height Affect Estimates of Patient Size in CT Scanning: A Phantom Study

    Energy Technology Data Exchange (ETDEWEB)

    Silosky, M; Marsh, R [University of Colorado School of Medicine, Aurora, CO (United States)

    2016-06-15

    Purpose: Localizer projection radiographs acquired prior to CT scans are used to estimate patient size, affecting the function of Automatic Tube Current Modulation (ATCM) and hence CTDIvol and SSDE. Due to geometric effects, the projected patient size varies with scanner table height and with the orientation of the localizer (AP versus PA). This study sought to determine if patient size estimates made from localizer scans is affected by variations in fat distribution, specifically when the widest part of the patient is not at the geometric center of the patient. Methods: Lipid gel bolus material was wrapped around an anthropomorphic phantom to simulate two different body mass distributions. The first represented a patient with fairly rigid fat and had a generally oval shape. The second was bell-shaped, representing corpulent patients more susceptible to gravity’s lustful tug. Each phantom configuration was imaged using an AP localizer and then a PA localizer. This was repeated at various scanner table heights. The width of the phantom was measured from the localizer and diagnostic images using in-house software. Results: 1) The projected phantom width varied up to 39% as table height changed.2) At some table heights, the width of the phantom, designed to represent larger patients, exceeded the localizer field of view, resulting in an underestimation of the phantom width.3) The oval-shaped phantom approached a normalized phantom width of 1 at a table height several centimeters lower (AP localizer) or higher (PA localizer) than did the bell-shaped phantom. Conclusion: Accurate estimation of patient size from localizer scans is dependent on patient positioning with respect to scanner isocenter and is limited in large patients. Further, patient size is more accurately measured on projection images if the widest part of the patient, rather than the geometric center of the patient, is positioned at scanner isocenter.

  1. Bismuth Infusion of ABS Enables Additive Manufacturing of Complex Radiological Phantoms and Shielding Equipment

    Directory of Open Access Journals (Sweden)

    Justin Ceh

    2017-02-01

    Full Text Available Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene filaments infused with varied concentrations of bismuth (1.2–2.7 g/cm3, a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT experiments of these filaments indicated that a density of 1.2 g/cm3 of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm3 created a stable material that could attenuate 50% of 99mTechnetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization.

  2. 3D printed phantoms mimicking cortical bone for the assessment of ultrashort echo time magnetic resonance imaging.

    Science.gov (United States)

    Rai, Robba; Manton, David; Jameson, Michael G; Josan, Sonal; Barton, Michael B; Holloway, Lois C; Liney, Gary P

    2018-02-01

    bone. The multicompartment anthropomorphic head phantom was successfully produced and able to simulate realistic air cavities, bony anatomy, and soft tissue. Image quality assessment in the tibia phantom using the PETRA sequence showed the suitability of the resin to mimic human anatomy with high SNR and contrast making it suitable for tissue segmentation. A solid resin material, which can be 3D printed, has been found to have similar magnetic resonance signal properties to human cortical bone. Phantoms replicating skeletal anatomy were successfully produced using this resin and demonstrated their use for image quality and segmentation assessment of ultrashort echo time sequences. © 2017 American Association of Physicists in Medicine.

  3. Design and characterization of a device to quantify the magnetic drug targeting efficiency of magnetic nanoparticles in a tube flow phantom by magnetic particle spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Radon, Patricia, E-mail: patricia.radon@ptb.de; Löwa, Norbert; Gutkelch, Dirk; Wiekhorst, Frank

    2017-04-01

    The aim of magnetic drug targeting (MDT) is to transfer a therapeutic drug coupled to magnetic nanoparticles (MNP) to desired disease locations (e.g. tumor region) with the help of magnetic field gradients. To transfer the MDT approach into clinical practice a number of important issues remain to be solved. We developed and characterized an in-vitro flow phantom to provide a defined and reproducible MDT environment. The tube system of the flow phantom is directed through the detection coil of a magnetic particle spectroscopy (MPS) device to determine the targeting efficiency. MPS offers an excellent temporal resolution of seconds and an outstanding specific sensitivity of some nanograms of iron. In the flow phantom different MNP types, magnet geometries and tube materials can be employed to vary physical parameters like diameter, flow rate, magnetic targeting gradient, and MNP properties. - Highlights: • Flow phantom for magnetic targeting. • MPS for quantitative MNP detection. • ng detection limit for MNP.

  4. Primary motor cortex changes after amputation correlate with phantom limb pain and the ability to move the phantom limb

    DEFF Research Database (Denmark)

    Raffin, Estelle; Richard, Nathalie; Giraux, Pascal

    2016-01-01

    A substantial body of evidence documents massive reorganization of primary sensory and motor cortices following hand amputation, the extent of which is correlated with phantom limb pain. Many therapies for phantom limb pain are based upon the idea that plastic changes after amputation...... for the maladaptative plasticity model, we demonstrate for the first time that motor capacities of the phantom limb correlate with post-amputation reorganization, and that this reorganization is not limited to the face and hand representations but also includes the proximal upper-limb....

  5. [Phantoms for the collection of genital secretions in stallions].

    Science.gov (United States)

    Klug, E; Brinkhoff, D; Flüge, A; Scherbarth, R; Essich, G; Kienzler, M

    1977-10-05

    Practical experiences of the phantom method for collection of genital secretions from stallions are reported. Taking a phantom used in the Richard-Götze-Haus Tierärztliche Hochschule Hannover as a prototype two further models slightly modified have been constructed, baring a flat hollow in the right side of the caudal phantom body for manual inserting of the Artificial Vagina. These three models fulfill four important conditions for routine use: (1) sufficient sexual attractivity for the stallions; 80-85% successful collections of presecretions out of a total of 1050 using the dummy and 70% successful semen collections from more than 240 in total; (2) solid and resistant construction; (3) easy cleaning and desinfection of the surface of the phantom to get representative samples; (4) firm installation on a hygienic floor.

  6. A solid tissue phantom for photon migration studies

    International Nuclear Information System (INIS)

    Cubeddu, Rinaldo; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Valentini, Gianluca

    1997-01-01

    A solid tissue phantom made of agar, Intralipid and black ink is described and characterized. The preparation procedure is fast and easily implemented with standard laboratory equipment. An instrumentation for time-resolved transmittance measurements was used to determine the optical properties of the phantom. The absorption and the reduced scattering coefficients are linear with the ink and Intralipid concentrations, respectively. A systematic decrease of the reduced scattering coefficient dependent on the agar content is observed, but can easily be managed. The phantom is highly homogeneous and shows good repeatability among different preparations. Moreover, agar inclusions can be easily embedded in either solid or liquid matrixes, and no artefacts are caused by the solid - solid or solid - liquid interfaces. This allows one to produce reliable and realistic inhomogeneous phantoms with known optical properties, particularly interesting for studies on optical imaging through turbid media. (author)

  7. Bioassay Phantoms Using Medical Images and Computer Aided Manufacturing

    International Nuclear Information System (INIS)

    Xu, X. Geroge

    2011-01-01

    A radiation bioassay program relies on a set of standard human phantoms to calibrate and assess radioactivity levels inside a human body for radiation protection and nuclear medicine imaging purposes. However, the methodologies in the development and application of anthropomorphic phantoms, both physical and computational, had mostly remained the same for the past 40 years. We herein propose a 3-year research project to develop medical image-based physical and computational phantoms specifically for radiation bioassay applications involving internally deposited radionuclides. The broad, long-term objective of this research was to set the foundation for a systematic paradigm shift away from the anatomically crude phantoms in existence today to realistic and ultimately individual-specific bioassay methodologies. This long-term objective is expected to impact all areas of radiation bioassay involving nuclear power plants, U.S. DOE laboratories, and nuclear medicine clinics.

  8. Phantom inflation and the 'Big Trip'

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, Pedro F. [Colina de los Chopos, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)]. E-mail: p.gonzalezdiaz@imaff.cfmac.csic.es; Jimenez-Madrid, Jose A. [Colina de los Chopos, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)

    2004-08-19

    Primordial inflation is regarded to be driven by a phantom field which is here implemented as a scalar field satisfying an equation of state p={omega}{rho}, with {omega}-1. Being even aggravated by the weird properties of phantom energy, this will pose a serious problem with the exit from the inflationary phase. We argue, however, in favor of the speculation that a smooth exit from the phantom inflationary phase can still be tentatively recovered by considering a multiverse scenario where the primordial phantom universe would travel in time toward a future universe filled with usual radiation, before reaching the big rip. We call this transition the 'Big Trip' and assume it to take place with the help of some form of anthropic principle which chooses our current universe as being the final destination of the time transition.

  9. A model for ultrasound contrast agent in a phantom vessel

    KAUST Repository

    Qamar, Adnan; Samtaney, Ravi

    2014-01-01

    A theoretical framework to model the dynamics of Ultrasound Contrast Agent (UCA) inside a phantom vessel is presented. The model is derived from the reduced Navier-Stokes equation and is coupled with the evolving flow field solution inside

  10. ICRU activity in the field of phantoms in diagnostic radiology

    International Nuclear Information System (INIS)

    Wambersie, A.; White, D.R.

    1992-01-01

    The ICRU Report on 'Phantoms and Computational Models in Radiation Therapy, Diagnosis and Protection' is presented. The Report contains a major section on human anatomy, from fetus to adult with the variations due to ethnic origin. Tolerance levels for the phantoms (composition, dimensions) are proposed and quality assurance programs are outlined. The report contains extensive appendices: human anatomical data and full specification of over 80 phantoms and computational models. ICRU Report 46 on 'Photon, electron, proton and neutron interaction data for body tissues' is closely related to the field of phantoms. It is a logical continuation on ICRU Report 44 (1989) on 'Tissue substitutes in radiation dosimetry and measurements' and contains the interaction data for more than 100 tissues, from fetal to adult, including some diseased tissues. (author)

  11. Phantom dark ghost in Einstein-Cartan gravity

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Chiao [National Taiwan University, Department of Physics, Taipei (China); National Taiwan University, LeCosPA, Taipei (China); Bouhmadi-Lopez, Mariam [University of the Basque Country UPV/EHU, Department of Theoretical Physics, P.O. Box 644, Bilbao (Spain); Basque Foundation for Science, IKERBASQUE, Bilbao (Spain); Chen, Pisin [National Taiwan University, Department of Physics, Taipei (China); National Taiwan University, LeCosPA, Taipei (China); National Taiwan University, Graduate Institute of Astrophysics, Taipei (China); SLAC National Accelerator Laboratory, Stanford University, Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA (United States)

    2017-05-15

    A class of dynamical dark energy models is constructed through an extended version of fermion fields corresponding to phantom dark ghost spinors, which are spin 1/2 with mass dimension 1. We find that if these spinors interact with torsion fields in a homogeneous and isotropic universe, then it does not imply any future dark energy singularity or any abrupt event, though the fermion has a negative kinetic energy. In fact, the equation of state of this dark energy model will asymptotically approach the value w = -1 from above without crossing the phantom divide and inducing therefore a de Sitter state. Consequently, we expect the model to be stable because no real phantom fields will be created. At late time, the torsion fields will vanish as the corresponding phantom dark ghost spinors dilute. As would be expected, intuitively, this result is unaffected by the presence of cold dark matter although the proof is not as straightforward as in general relativity. (orig.)

  12. Phantom's construction for dose measurement in brachytherapy

    International Nuclear Information System (INIS)

    Tri Harjanto; Hidayat Joko Puspito; Joko Triyanto

    2009-01-01

    In nuclear medicine, dose rate validation is the key for a successful process in therapy and diagnose of any deases. Therefore, the brachytherapy equipment being designed and constructed is to be validated its dose rate received by the radiated object. A phantom for such validation purpose is designed and constructed as a correct as if on site geometrical position of sources. The design of phantom consists of seven layers of flexi glass plates: 10 mm thick, 105 mm wide, and 280 mm length. All the plates are to be holed according to the size of the applicator to be used. Every surface of the flexi glass layers is grooved 1 mm wide, 1 mm depth, and 10 mm distance between the groove. The applicator inside the phantom is positioned at a certain reference for measurement. Every TLD installed has a fix position toward the reference coordinate and has an index number. By this system of phantom, the isodose system can be plotted. (author)

  13. Validation of a Monte Carlo model used for simulating tube current modulation in computed tomography over a wide range of phantom conditions/challenges

    Energy Technology Data Exchange (ETDEWEB)

    Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Cagnon, Chris H.; McNitt-Gray, Michael F. [Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90024 (United States); DeMarco, John J. [Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, California 90095 (United States)

    2014-11-01

    Purpose: Monte Carlo (MC) simulation methods have been widely used in patient dosimetry in computed tomography (CT), including estimating patient organ doses. However, most simulation methods have undergone a limited set of validations, often using homogeneous phantoms with simple geometries. As clinical scanning has become more complex and the use of tube current modulation (TCM) has become pervasive in the clinic, MC simulations should include these techniques in their methodologies and therefore should also be validated using a variety of phantoms with different shapes and material compositions to result in a variety of differently modulated tube c