Comparison of different phantoms used in digital diagnostic imaging

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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.

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)

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

Science.gov (United States)

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.

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

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

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

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

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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.  

Development and application of anthropomorphic voxel phantom of the head for in vivo measurement.

Science.gov (United States)

Vrba, T

2007-01-01

The in vivo measurement of the activity deposited in the skeleton is a very useful source of information on human internal contaminations with transuranic elements, e.g. americium 241, especially for long time periods after intake. Measurements are performed on the skull or the larger joints such as the knee or elbow. The paper deals with the construction of an anthropomorphic numerical phantom based on CT scans, its potential for calibration and the estimation of the uncertainties of the detection system. The density of bones, activity distribution and position of the detectors were changed in individual simulations in order to estimate their effects on the result of the measurement. The results from simulations with the numerical phantom were compared with the results of physical phantoms.

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.

A pneumatic phantom for mimicking respiration-induced artifacts in spinal MRI.

Science.gov (United States)

De Tillieux, Philippe; Topfer, Ryan; Foias, Alexandru; Leroux, Iris; El Maâchi, Imanne; Leblond, Hugues; Stikov, Nikola; Cohen-Adad, Julien

2018-01-01

To design a phantom capable of mimicking human respiration to serve as a testing platform for correction of the static and time-evolving magnetic field distortions typically encountered in MRI of the spinal cord. An inflation system to mimic the air variation of the human lungs was constructed. The inflation system was linked to a phantom containing synthetic lungs and an ex vivo human spine. The relationship between air pressure and phantom lung volume was evaluated via imaging experiment. The geometric distortion (pseudo-displacement) caused by the B0 inhomogeneities was measured on echo planar imaging slices for different air volumes. Linear and quadratic relations linking air pressure to phantom lung volume were observed with a Pearson correlation coefficient of 0.99. Air distribution was uneven across the synthetic lungs, exhibiting a left-to-right lung volume ratio of up to 5/4. The pseudo-displacement artifact of the spine caused by the air-filled lungs was observed. The proposed phantom can reproduce the lung volume variation of human respiration and thus can serve as a reliable testing platform for the correction of the associated time-varying B 0 field distortions. Details of the construction and code for the inflation system microcontroller are available for download as open source. Magn Reson Med 79:600-605, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

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)

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)

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)

The properties of human body phantoms used in calculations of electromagnetic fields exposure by wireless communication handsets or hand-operated industrial devices.

Science.gov (United States)

Zradziński, Patryk

2013-06-01

According to international guidelines, the assessment of biophysical effects of exposure to electromagnetic fields (EMF) generated by hand-operated sources needs the evaluation of induced electric field (E(in)) or specific energy absorption rate (SAR) caused by EMF inside a worker's body and is usually done by the numerical simulations with different protocols applied to these two exposure cases. The crucial element of these simulations is the numerical phantom of the human body. Procedures of E(in) and SAR evaluation due to compliance analysis with exposure limits have been defined in Institute of Electrical and Electronics Engineers standards and International Commission on Non-Ionizing Radiation Protection guidelines, but a detailed specification of human body phantoms has not been described. An analysis of the properties of over 30 human body numerical phantoms was performed which has been used in recently published investigations related to the assessment of EMF exposure by various sources. The differences in applicability of these phantoms in the evaluation of E(in) and SAR while operating industrial devices and SAR while using mobile communication handsets are discussed. The whole human body numerical phantom dimensions, posture, spatial resolution and electric contact with the ground constitute the key parameters in modeling the exposure related to industrial devices, while modeling the exposure from mobile communication handsets, which needs only to represent the exposed part of the human body nearest to the handset, mainly depends on spatial resolution of the phantom. The specification and standardization of these parameters of numerical human body phantoms are key requirements to achieve comparable and reliable results from numerical simulations carried out for compliance analysis against exposure limits or within the exposure assessment in EMF-related epidemiological studies.

Numerical compliance testing of human exposure to electromagnetic radiation from smart-watches.

Science.gov (United States)

Hong, Seon-Eui; Lee, Ae-Kyoung; Kwon, Jong-Hwa; Pack, Jeong-Ki

2016-10-07

In this study, we investigated the electromagnetic dosimetry for smart-watches. At present, the standard for compliance testing of body-mounted and handheld devices specifies the use of a flat phantom to provide conservative estimates of the peak spatial-averaged specific absorption rate (SAR). This means that the estimated SAR using a flat phantom should be higher than the SAR in the exposure part of an anatomical human-body model. To verify this, we numerically calculated the SAR for a flat phantom and compared it with the numerical calculation of the SAR for four anatomical human-body models of different ages. The numerical analysis was performed using the finite difference time domain method (FDTD). The smart-watch models were used in the three antennas: the shorted planar inverted-F antenna (PIFA), loop antenna, and monopole antenna. Numerical smart-watch models were implemented for cellular commutation and wireless local-area network operation at 835, 1850, and 2450 MHz. The peak spatial-averaged SARs of the smart-watch models are calculated for the flat phantom and anatomical human-body model for the wrist-worn and next to mouth positions. The results show that the flat phantom does not provide a consistent conservative SAR estimate. We concluded that the difference in the SAR results between an anatomical human-body model and a flat phantom can be attributed to the different phantom shapes and tissue structures.

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

Detecting breast microcalcifications using super-resolution and wave-equation ultrasound imaging: a numerical phantom study

Energy Technology Data Exchange (ETDEWEB)

Huang, Lianjie [Los Alamos National Laboratory; Simonetti, Francesco [IMPERIAL COLLEGE LONDON; Huthwaite, Peter [IMPERIAL COLLEGE LONDON; Rosenberg, Robert [UNM; Williamson, Michael [UNM

2010-01-01

Ultrasound image resolution and quality need to be significantly improved for breast microcalcification detection. Super-resolution imaging with the factorization method has recently been developed as a promising tool to break through the resolution limit of conventional imaging. In addition, wave-equation reflection imaging has become an effective method to reduce image speckles by properly handling ultrasound scattering/diffraction from breast heterogeneities during image reconstruction. We explore the capabilities of a novel super-resolution ultrasound imaging method and a wave-equation reflection imaging scheme for detecting breast microcalcifications. Super-resolution imaging uses the singular value decomposition and a factorization scheme to achieve an image resolution that is not possible for conventional ultrasound imaging. Wave-equation reflection imaging employs a solution to the acoustic-wave equation in heterogeneous media to backpropagate ultrasound scattering/diffraction waves to scatters and form images of heterogeneities. We construct numerical breast phantoms using in vivo breast images, and use a finite-difference wave-equation scheme to generate ultrasound data scattered from inclusions that mimic microcalcifications. We demonstrate that microcalcifications can be detected at full spatial resolution using the super-resolution ultrasound imaging and wave-equation reflection imaging methods.

Development of Traceable Phantoms for Improved Image Quantification in Positron Emission Tomography

Science.gov (United States)

Zimmerman, Brian

2014-03-01

Clinical trials for new drugs increasingly rely on imaging data to monitor patient response to the therapy being studied. In the case of radiopharmaceutical applications, imaging data are also used to estimate organ and tumor doses in order to arrive at the optimal dosage for safe and effective treatment. Positron Emission Tomography (PET) is one of the most commonly used imaging modalities for these types of applications. In large, multicenter trials it is crucial to minimize as much as possible the variability that arises due to use of different types of scanners and other instrumentation so that the biological response can be more readily evaluated. This can be achieved by ensuring that all the instruments are calibrated to a common standard and that their performance is continuously monitored throughout the trial. Maintaining links to a single standard also enables the comparability of data acquired on a heterogeneous collection of instruments in different clinical settings. As the standards laboratory for the United States, the National Institute of Standards and Technology (NIST) has been developing a suite of phantoms having traceable activity content to enable scanner calibration and performance testing. The configurations range from small solid cylindrical sources having volumes from 1 mL to 23 mL to large cylinders having a total volume of 9 L. The phantoms are constructed with 68Ge as a long-lived substitute for the more clinically useful radionuclide 18F. The contained activity values are traceable to the national standard for 68Ge and are also linked to the standard for 18F through a careful series of comparisons. The techniques that have been developed are being applied to a variety of new phantom configurations using different radionuclides. Image-based additive manufacturing techniques are also being investigated to create fillable phantoms having irregular shapes which can better mimic actual organs and tumors while still maintaining traceability

Development and application of the Chinese adult female computational phantom Rad-HUMAN

International Nuclear Information System (INIS)

Wu, Yican; Cheng, Mengyun; Wang, Wen; Fan, Yanchang; Zhao, Kai; He, Tao; Pei, Xi; Shang, Leiming; Chen, Chaobin; Long, Pengcheng; Cao, Ruifen; Wang, Guozhong; Zhou, Shaoheng; Yu, Shengpeng; Hu, Liqin; Zeng, Q.

2013-01-01

Rad-HUMAN is a whole-body numerical phantom of a Chinese adult woman which contains 46 organs and tissues and was created by MCAM6 software using the color photographs of the Chinese Visible Human dataset. This dataset was obtained from a 22-year old Chinese female cadaver judged to represent normal human anatomy as much as possible. The density and elemental composition recommended in the ICRP Publication 89 and in the ICRU report 44 were assigned to the organ and tissue in Rad-HUMAN for radiation protection purpose. The last step was to implement the anatomical data into a Monte Carlo code. Rad-HUMAN contains more than 28.8 billion tiny volume units, which produces an accurately whole-body numerical phantom of a Chinese adult female

Application of Voxel Phantoms to Study the Influence of Heterogeneous Distribution of Actinides in Lungs on In Vivo Counting Calibration Factors Using Animal Experimentations

Energy Technology Data Exchange (ETDEWEB)

Lamart, S.; Pierrat, N.; De Carlan, L.; Franck, D. [IRSN/DRPH/SDI/LEDI, BP 17, F-92 262 Fontenay-aux-Roses (France); Dudoignon, N. [IRSN/DRPH/SRBE/LRPAT, BP 17, F-92 262 Fontenay-aux-Roses (France); Rateau, S.; Van der Meeren, A.; Rouit, E. [CEA/DSV/DRR/SRCA/LRT BP no 12, F-91680 Bruyeres-le-Chatel (France); Bottlaender, M. [CEA/SHFJ, 4, place du General Leclerc F-91400 Orsay (France)

2006-07-01

Calibration of lung counting system dedicated to retention assessment of actinides in the lungs remains critical due to large uncertainties in calibration factors. Among them, the detector positioning, the chest wall thickness and composition (muscle/fat) assessment, and the distribution of the contamination are the main parameters influencing the detector response. In order to reduce these uncertainties, a numerical approach based on the application of voxel phantoms (numerical phantoms based on tomographic images, CT or MRI) associated to a Monte-Carlo code (namely M.C.N.P.) was developed. It led to the development of a dedicated tool, called O.E.D.I.P.E., that allows to easily handle realistic voxel phantoms for the simulation of in vivo measurement (or dose calculation, application that will not be presented in this paper). The goal of this paper is to present our study of the influence of the lung distribution on calibration factors using both animal experimentations and our numerical method. Indeed, physical anthropomorphic phantoms used for calibration always consider a uniform distribution of the source in the lungs, which is not true in many contamination conditions. The purpose of the study is to compare the response of the measurement detectors using a real distribution of actinide particles in the lungs, obtained from animal experimentations, with the homogeneous one considered as the reference. This comparison was performed using O.E.D.I.P.E. that can almost simulate any source distribution. A non human primate was contaminated heterogeneously by intra-tracheal administration of actinide oxide. After euthanasia, gamma spectrometry measurements were performed on the pulmonary lobes to obtain the distribution of the contamination in the lungs. This realistic distribution was used to simulate an heterogeneous contamination in the numerical phantom of the non human primate, which was compared with a simulation of an homogeneous contamination presenting the

Application of Voxel Phantoms to Study the Influence of Heterogeneous Distribution of Actinides in Lungs on In Vivo Counting Calibration Factors Using Animal Experimentations

International Nuclear Information System (INIS)

Lamart, S.; Pierrat, N.; De Carlan, L.; Franck, D.; Dudoignon, N.; Rateau, S.; Van der Meeren, A.; Rouit, E.; Bottlaender, M.

2006-01-01

Calibration of lung counting system dedicated to retention assessment of actinides in the lungs remains critical due to large uncertainties in calibration factors. Among them, the detector positioning, the chest wall thickness and composition (muscle/fat) assessment, and the distribution of the contamination are the main parameters influencing the detector response. In order to reduce these uncertainties, a numerical approach based on the application of voxel phantoms (numerical phantoms based on tomographic images, CT or MRI) associated to a Monte-Carlo code (namely M.C.N.P.) was developed. It led to the development of a dedicated tool, called O.E.D.I.P.E., that allows to easily handle realistic voxel phantoms for the simulation of in vivo measurement (or dose calculation, application that will not be presented in this paper). The goal of this paper is to present our study of the influence of the lung distribution on calibration factors using both animal experimentations and our numerical method. Indeed, physical anthropomorphic phantoms used for calibration always consider a uniform distribution of the source in the lungs, which is not true in many contamination conditions. The purpose of the study is to compare the response of the measurement detectors using a real distribution of actinide particles in the lungs, obtained from animal experimentations, with the homogeneous one considered as the reference. This comparison was performed using O.E.D.I.P.E. that can almost simulate any source distribution. A non human primate was contaminated heterogeneously by intra-tracheal administration of actinide oxide. After euthanasia, gamma spectrometry measurements were performed on the pulmonary lobes to obtain the distribution of the contamination in the lungs. This realistic distribution was used to simulate an heterogeneous contamination in the numerical phantom of the non human primate, which was compared with a simulation of an homogeneous contamination presenting the

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).

Phantom sensation as experienced by people with a spinal cord injury

OpenAIRE

Drysdale, Daren

2012-01-01

All the approaches in this thesis are linked by a common query: What is the meaning, structure and essence of the lived experience for a person with a Spinal Cord Injury (SCI) who perceives phantom sensation and/or pain? (See Figure 1). The thesis will allow you to form an accurate impression of phantom sensation in the population of people with a spinal cord injury and it highlights some of the confusion surrounding the terms now in common use. As the thesis progresses, the review of the lit...

Balloon sheaths for gastrointestinal guidance and access: a preliminary phantom study

International Nuclear Information System (INIS)

He, Xu; Shin, Ji Hoon; Kim, Hyo Cheol; Woo, Cheol Woong; Woo, Sung Ha; Choi, Won Chan; Kim, Jong Gyu; Lim, Jin Oh; Kim, Tae Hyung; Yoon, Chang Jin; Song, Ho Young; Kang, Wee Chang

2005-01-01

We wanted to evaluate the feasibility and usefulness of a newly designed balloon sheath for gastrointestinal guidance and access by conducting a phantom study. The newly designed balloon sheath consisted of an introducer sheath and a supporting balloon. A coil catheter was advanced over a guide wire into two gastroduodenal phantoms (one was with stricture and one was without stricture); group I was without a balloon sheath, group II was with a deflated balloon sheath, and groups III and IV were with an inflated balloon and with the balloon in the fundus and body, respectively. Each test was performed for 2 minutes and it was repeated 10 times in each group by two researchers, and the positions reached by the catheter tip were recorded. Both researchers had better performances with both phantoms in order of group IV, III, II and I. In group IV, both researchers advanced the catheter tip through the fourth duodenal segment in both the phantoms. In group I, however, the catheter tip never reached the third duodenal segment in both the phantoms by both the researchers. The numeric values for the four study groups were significantly different for both the phantoms (ρ < 0.001). A significant difference was also found between group III and IV for both phantoms (ρ < 0.001). The balloon sheath seems to be feasible for clinical use, and it has good clinical potential for gastrointestinal guidance and access, particularly when the inflated balloon is placed in the gastric body

A quantitative evaluation of multiple biokinetic models using an assembled water phantom: A feasibility study.

Directory of Open Access Journals (Sweden)

Da-Ming Yeh

Full Text Available This study examined the feasibility of quantitatively evaluating multiple biokinetic models and established the validity of the different compartment models using an assembled water phantom. Most commercialized phantoms are made to survey the imaging system since this is essential to increase the diagnostic accuracy for quality assurance. In contrast, few customized phantoms are specifically made to represent multi-compartment biokinetic models. This is because the complicated calculations as defined to solve the biokinetic models and the time-consuming verifications of the obtained solutions are impeded greatly the progress over the past decade. Nevertheless, in this work, five biokinetic models were separately defined by five groups of simultaneous differential equations to obtain the time-dependent radioactive concentration changes inside the water phantom. The water phantom was assembled by seven acrylic boxes in four different sizes, and the boxes were linked to varying combinations of hoses to signify the multiple biokinetic models from the biomedical perspective. The boxes that were connected by hoses were then regarded as a closed water loop with only one infusion and drain. 129.1±24.2 MBq of Tc-99m labeled methylene diphosphonate (MDP solution was thoroughly infused into the water boxes before gamma scanning; then the water was replaced with de-ionized water to simulate the biological removal rate among the boxes. The water was driven by an automatic infusion pump at 6.7 c.c./min, while the biological half-life of the four different-sized boxes (64, 144, 252, and 612 c.c. was 4.8, 10.7, 18.8, and 45.5 min, respectively. The five models of derived time-dependent concentrations for the boxes were estimated either by a self-developed program run in MATLAB or by scanning via a gamma camera facility. Either agreement or disagreement between the practical scanning and the theoretical prediction in five models was thoroughly discussed. The

Evaluating phantom image quality parameters to optimise patient radiation dose in dental digital radiology.

Science.gov (United States)

Gonzalez, Luciano; Vano, Eliseo; Fernandez, Ramon; Ziraldo, Viviana; Delgado, Jaime; Delgado, Victor; Moro, Javier; Ubeda, Carlos

2012-08-01

Our objective was to obtain images of a predictable level of quality using an intraoral X-ray system with digital imaging, avoiding patient overexposure. A polymethylmethacrylate (PMMA) physical test phantom was imaged at different exposure times and at various PMMA thicknesses using a dental imaging coupled charge device. Two identical regions of interest (ROIs) were chosen in every image file, and quality was numerically evaluated by measuring high-contrast spatial resolutions, low-contrast thresholds and signal-to-noise ratios. In addition, three practitioners proposed personal quality scores by image inspection. Numerical contents in the ROIs, related to the image quality, were plotted against exposure time. From here, a simple expression linking the exposure time with the thickness to obtain images of comparable quality was deduced. As a result, the optimum exposure time for imaging with a predictable level of quality can be inferred. The potential effect could imply savings above 1000 man Sv, roughly 20 % of the collective dose due to dental imaging, over a population of 1540 millions.

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

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.

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.)

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...

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.

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

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

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)

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.

CT images of an anthropomorphic and anthropometric male pelvis phantom

Energy Technology Data Exchange (ETDEWEB)

Matos, Andrea S.D. de; Campos, Tarcisio P.R. de, E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares

2009-07-01

Actually, among of the most often neoplasm types are the cancer of prostate, bladder and intestine. The incidence of the intestine neoplasm in Brazil is at fourth among the most frequent tumors of the male sex, barely close to the stomach, lung and prostate incidences. Phantoms are objects used as simulators for investigating ionizing radiation transport on humans, especially during radiation therapy or radiological diagnostic. The purpose of this work is the achievement of a set of computerized tomography (CT) images of a male pelvis phantom, with anthropomorphic and anthropometric features. It investigates and analyses the set of phantom CT images in according to a correspondent human pelvis one. The reason to develop a pelvis phantom is the needs of reproducing well established spatial dose distribution in radiation therapy, especially during calibration and protocol setup for various pelvis neoplasms. It aims to produce dose optimization on radiation therapy, improving health tissue protection and keeping control tumor dose. A male pelvis phantom with similar shape made of equivalent tissues was built for simulating the ionizing radiation transport to the human body. At the phantom, pelvis organs were reproduced including the bladder, the intestine, the prostate, the muscular and greasy tissue, as well as the bone tissue and the skin. A set of CT images was carried out in axial thin sections of 2mm thickness. As results, the constituent tissues had a tomography response on Hounsfield scale similar to values found on the human pelvis. Each tissue has its respective Hounsfield value, demonstrated here. The CT images also show that the organs have equivalent anthropometric measures and anthropomorphic features of the radiological human anatomy. The anatomical physical arrangement of the organs is also similar to of the pelvis human male, having the scales of gray and numerical scale of Hounsfield compatible with the scale of the human tissue. The phantom presents

CT images of an anthropomorphic and anthropometric male pelvis phantom

International Nuclear Information System (INIS)

Matos, Andrea S.D. de; Campos, Tarcisio P.R. de

2009-01-01

Actually, among of the most often neoplasm types are the cancer of prostate, bladder and intestine. The incidence of the intestine neoplasm in Brazil is at fourth among the most frequent tumors of the male sex, barely close to the stomach, lung and prostate incidences. Phantoms are objects used as simulators for investigating ionizing radiation transport on humans, especially during radiation therapy or radiological diagnostic. The purpose of this work is the achievement of a set of computerized tomography (CT) images of a male pelvis phantom, with anthropomorphic and anthropometric features. It investigates and analyses the set of phantom CT images in according to a correspondent human pelvis one. The reason to develop a pelvis phantom is the needs of reproducing well established spatial dose distribution in radiation therapy, especially during calibration and protocol setup for various pelvis neoplasms. It aims to produce dose optimization on radiation therapy, improving health tissue protection and keeping control tumor dose. A male pelvis phantom with similar shape made of equivalent tissues was built for simulating the ionizing radiation transport to the human body. At the phantom, pelvis organs were reproduced including the bladder, the intestine, the prostate, the muscular and greasy tissue, as well as the bone tissue and the skin. A set of CT images was carried out in axial thin sections of 2mm thickness. As results, the constituent tissues had a tomography response on Hounsfield scale similar to values found on the human pelvis. Each tissue has its respective Hounsfield value, demonstrated here. The CT images also show that the organs have equivalent anthropometric measures and anthropomorphic features of the radiological human anatomy. The anatomical physical arrangement of the organs is also similar to of the pelvis human male, having the scales of gray and numerical scale of Hounsfield compatible with the scale of the human tissue. The phantom presents

Design and Construction of a Test Phantom for Screen/Film Mammography Quality Control

International Nuclear Information System (INIS)

Galvan, Hector; Grabski, Varlen; Ruiz, Cesar; Brandan, Maria-Ester; Villasenor, Yolanda

2006-01-01

A 10 x 10 x 4 cm Lucite phantom for quality control tests in mammography has been designed and built. It contains internal elements to quantify contrast and resolution, a mixture of talc and Lucite fibers to simulate the breast architecture, a 9-step aluminum wedge to verify the constancy of the film developing process, and metallic foils to evaluate kVp. Associated with an ionization chamber, the mean glandular dose can be evaluated. Its performance has been compared against the phantom accredited by the American College of Radiology. For a series of kV, both phantoms OD are similar within 5%. The step wedge can detect developer temperature changes of ±1 deg. C. Relative metal foils/acrylic OD permits to calculate kVp with precision of ±0.43 kV. Radiological measurements have been interpreted by numerical calculations

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)

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.

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

An improved MCNP version of the NORMAN voxel phantom for dosimetry studies.

Science.gov (United States)

Ferrari, P; Gualdrini, G

2005-09-21

In recent years voxel phantoms have been developed on the basis of tomographic data of real individuals allowing new sets of conversion coefficients to be calculated for effective dose. Progress in radiation studies brought ICRP to revise its recommendations and a new report, already circulated in draft form, is expected to change the actual effective dose evaluation method. In the present paper the voxel phantom NORMAN developed at HPA, formerly NRPB, was employed with MCNP Monte Carlo code. A modified version of the phantom, NORMAN-05, was developed to take into account the new set of tissues and weighting factors proposed in the cited ICRP draft. Air kerma to organ equivalent dose and effective dose conversion coefficients for antero-posterior and postero-anterior parallel photon beam irradiations, from 20 keV to 10 MeV, have been calculated and compared with data obtained in other laboratories using different numerical phantoms. Obtained results are in good agreement with published data with some differences for the effective dose calculated employing the proposed new tissue weighting factors set in comparison with previous evaluations based on the ICRP 60 report.

Development of Phantom Limb Pain after Femoral Nerve Block

Directory of Open Access Journals (Sweden)

Sadiah Siddiqui

2014-01-01

Full Text Available Historically, phantom limb pain (PLP develops in 50–80% of amputees and may arise within days following an amputation for reasons presently not well understood. Our case involves a 29-year-old male with previous surgical amputation who develops PLP after the performance of a femoral nerve block. Although there have been documented cases of reactivation of PLP in amputees after neuraxial technique, there have been no reported events associated with femoral nerve blockade. We base our discussion on the theory that symptoms of phantom limb pain are of neuropathic origin and attempt to elaborate the link between regional anesthesia and PLP. Further investigation and understanding of PLP itself will hopefully uncover a relationship between peripheral nerve blocks targeting an affected limb and the subsequent development of this phenomenon, allowing physicians to take appropriate steps in prevention and treatment.

``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.

Temporal analysis of reflected optical signals for short pulse laser interaction with nonhomogeneous tissue phantoms

International Nuclear Information System (INIS)

Trivedi, Ashish; Basu, Soumyadipta; Mitra, Kunal

2005-01-01

The use of short pulse laser for minimally invasive detection scheme has become an indispensable tool in the technological arsenal of modern medicine and biomedical engineering. In this work, a time-resolved technique has been used to detect tumors/inhomogeneities in tissues by measuring transmitted and reflected scattered temporal optical signals when a short pulse laser source is incident on tissue phantoms. A parametric study involving different scattering and absorption coefficients of tissue phantoms and inhomogeneities, size of inhomogeneity as well as the detector position is performed. The experimental measurements are validated with a numerical solution of the transient radiative transport equation obtained by using discrete ordinates method. Thus, both simultaneous experimental and numerical studies are critical for predicting the optical properties of tissues and inhomogeneities from temporal scattered optical signal measurements

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

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

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.

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.

An innovative phantom for quantitative and qualitative investigation of advanced x-ray imaging technologies

International Nuclear Information System (INIS)

Chiarot, C B; Siewerdsen, J H; Haycocks, T; Moseley, D J; Jaffray, D A

2005-01-01

Development, characterization, and quality assurance of advanced x-ray imaging technologies require phantoms that are quantitative and well suited to such modalities. This note reports on the design, construction, and use of an innovative phantom developed for advanced imaging technologies (e.g., multi-detector CT and the numerous applications of flat-panel detectors in dual-energy imaging, tomosynthesis, and cone-beam CT) in diagnostic and image-guided procedures. The design addresses shortcomings of existing phantoms by incorporating criteria satisfied by no other single phantom: (1) inserts are fully 3D-spherically symmetric rather than cylindrical; (2) modules are quantitative, presenting objects of known size and contrast for quality assurance and image quality investigation; (3) features are incorporated in ideal and semi-realistic (anthropomorphic) contexts; and (4) the phantom allows devices to be inserted and manipulated in an accessible module (right lung). The phantom consists of five primary modules: (1) head, featuring contrast-detail spheres approximate to brain lesions; (2) left lung, featuring contrast-detail spheres approximate to lung modules; (3) right lung, an accessible hull in which devices may be placed and manipulated; (4) liver, featuring conrast-detail spheres approximate to metastases; and (5) abdomen/pelvis, featuring simulated kidneys, colon, rectum, bladder, and prostate. The phantom represents a two-fold evolution in design philosophy-from 2D (cylindrically symmetric) to fully 3D, and from exclusively qualitative or quantitative to a design accommodating quantitative study within an anatomical context. It has proven a valuable tool in investigations throughout our institution, including low-dose CT, dual-energy radiography, and cone-beam CT for image-guided radiation therapy and surgery. (note)

Development of a pregnant woman phantom using polygonal mesh, for dosimetric evaluations

Energy Technology Data Exchange (ETDEWEB)

Cabral, Manuela O.M.; Vieira, Jose W., E-mail: manuela.omc@gmail.com [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear; Leal Neto, Viriato, E-mail: viriatoleal@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil); Lima, Fernando R.A., E-mail: falima@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

2014-07-01

Due to the embryo/fetus radiosensitivity the accurate estimation of the absorbed dose distribution in the abdominal area is an additional problem caused by the exposure of pregnant women to ionizing radiation in medical applications. This paper reports the construction and insertion of a fetal representation in a female geometry by means of 3D modeling techniques. In order to characterize an ECM the Grupo de Dosimetria Numerica (GDN) is using, mainly, simulators emitting gamma sources and voxel phantoms coupled to a MC code. The phantoms are predominantly constructed from stacks of magnetic resonance images (MRI), computed tomography (CT) (obtained from scans of real patients) or from 3D modeling techniques. Due to the difficulty of obtaining medical images of pregnant women, 3D objects in several formats (.obj, .max, .blend, etc.) were acquired for anatomical representation of a non-pregnant adult. To construct a fetal representation, the 3D modeling technique called Poly Modeling (polygon mesh) was used inside of the software Autodesk 3ds Max 2014 (free student version). Information about the radiosensibility of organs included in the abdominal area will be used to fit and use the pregnant phantom in numerical dosimetry. For this, the phantom will be voxelized and the masses of organs of interest will be adjusted according to data provided by International Commission on Radiological Protection (ICRP). Finally, the phantom will be coupled to a MC code creating a MCE that will serve as base for the construction of several other models involving pregnant women submitted to ionizing radiation. (author)

Development of a pregnant woman phantom using polygonal mesh, for dosimetric evaluations

International Nuclear Information System (INIS)

Cabral, Manuela O.M.; Vieira, Jose W.; Lima, Fernando R.A.

2014-01-01

Due to the embryo/fetus radiosensitivity the accurate estimation of the absorbed dose distribution in the abdominal area is an additional problem caused by the exposure of pregnant women to ionizing radiation in medical applications. This paper reports the construction and insertion of a fetal representation in a female geometry by means of 3D modeling techniques. In order to characterize an ECM the Grupo de Dosimetria Numerica (GDN) is using, mainly, simulators emitting gamma sources and voxel phantoms coupled to a MC code. The phantoms are predominantly constructed from stacks of magnetic resonance images (MRI), computed tomography (CT) (obtained from scans of real patients) or from 3D modeling techniques. Due to the difficulty of obtaining medical images of pregnant women, 3D objects in several formats (.obj, .max, .blend, etc.) were acquired for anatomical representation of a non-pregnant adult. To construct a fetal representation, the 3D modeling technique called Poly Modeling (polygon mesh) was used inside of the software Autodesk 3ds Max 2014 (free student version). Information about the radiosensibility of organs included in the abdominal area will be used to fit and use the pregnant phantom in numerical dosimetry. For this, the phantom will be voxelized and the masses of organs of interest will be adjusted according to data provided by International Commission on Radiological Protection (ICRP). Finally, the phantom will be coupled to a MC code creating a MCE that will serve as base for the construction of several other models involving pregnant women submitted to ionizing radiation. (author)

PID - 3D: a software to develop mathematical human phantoms for use in computational dosimetry

International Nuclear Information System (INIS)

Lima Filho, Jose de Melo; Vieira, Jose Wilson; Lima, Vanildo Junior de Melo; Lima, Fernando Roberto de Andrade

2009-01-01

The PID-3D software, written in Visual C++, contains tools developed for building and editing of three-dimensional geometric figures formed of voxels (volume pixels). These tools were projected to be used, together with those already developed by the Grupo de Dosimetria Numerica (GDN/CNPq), such as the FANTOMAS and DIP software, in computational dosimetry of ionizing radiation. The main objective of this paper is to develop various voxel-based geometric solids to build voxel phantoms (meaning models), anthropomorphic or not. The domain of this technique of development of geometric solids is important for the GDN/CNPq, because it allows the use of just one Monte Carlo code to simulate the transportation, interaction and deposition of radiation in tomographic and mathematical phantoms. Building a particular geometric solid the user needs to inform to the PID-3D software, the location and the size of the parallelepiped that involves it. Each built solid can be saved in a binary file of the type SGI (file containing the size and the numeric values that constitutes the 3D matrix that represents the solid, commonly used by GDN/CNPq). The final mathematical phantom is built starting from these SGI files and the SGI file resulting constitutes a voxel phantom. With this approach the software's user does not have to manipulate the equations and inequalities of the solids that represent the organs and tissues of the phantom. The 3D-PID software, associated with the FANTOMAS and DIP software are tools produced by GDN/CNPq, providing a new technique for building of 3D scenes in dosimetric evaluations using voxel phantoms. To validate the PID-3D software one built, step by step, a phantom similar to the MIRD-5 stylized phantom. (author)

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

Using case-based reasoning for the reconstitution and manipulation of voxelized phantoms

International Nuclear Information System (INIS)

Henriet, J.; Fontaine, E.; Bopp, M.; Makovicka, L.; Farah, J.; Broggio, D.; Franck, D.; Chebel-Morello, B.

2010-01-01

The authors reports the development of the EquiVox platform, the aim of which is to allow a radioprotection expert (physician, biologist or other) to work with a phantom which will be the closest possible to the examined person in order to make an as precise as possible dosimetric assessment. The objective is to help to select the best phantom among those the expert knows depending on the assessment type he wants to make. First, they present the general principles of the case-based reasoning, and then the EquiVox platform which proposes all the steps: formalization, elaboration, comparison, and so on. Based on typical numerical values associated with different morphological characteristics, they present and discuss graphical results obtained by the platform. They also discuss their validity and reliability

NOTE: An innovative phantom for quantitative and qualitative investigation of advanced x-ray imaging technologies

Science.gov (United States)

Chiarot, C. B.; Siewerdsen, J. H.; Haycocks, T.; Moseley, D. J.; Jaffray, D. A.

2005-11-01

Development, characterization, and quality assurance of advanced x-ray imaging technologies require phantoms that are quantitative and well suited to such modalities. This note reports on the design, construction, and use of an innovative phantom developed for advanced imaging technologies (e.g., multi-detector CT and the numerous applications of flat-panel detectors in dual-energy imaging, tomosynthesis, and cone-beam CT) in diagnostic and image-guided procedures. The design addresses shortcomings of existing phantoms by incorporating criteria satisfied by no other single phantom: (1) inserts are fully 3D—spherically symmetric rather than cylindrical; (2) modules are quantitative, presenting objects of known size and contrast for quality assurance and image quality investigation; (3) features are incorporated in ideal and semi-realistic (anthropomorphic) contexts; and (4) the phantom allows devices to be inserted and manipulated in an accessible module (right lung). The phantom consists of five primary modules: (1) head, featuring contrast-detail spheres approximate to brain lesions; (2) left lung, featuring contrast-detail spheres approximate to lung modules; (3) right lung, an accessible hull in which devices may be placed and manipulated; (4) liver, featuring conrast-detail spheres approximate to metastases; and (5) abdomen/pelvis, featuring simulated kidneys, colon, rectum, bladder, and prostate. The phantom represents a two-fold evolution in design philosophy—from 2D (cylindrically symmetric) to fully 3D, and from exclusively qualitative or quantitative to a design accommodating quantitative study within an anatomical context. It has proven a valuable tool in investigations throughout our institution, including low-dose CT, dual-energy radiography, and cone-beam CT for image-guided radiation therapy and surgery.

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

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

Limiting CT radiation dose in children with craniosynostosis: phantom study using model-based iterative reconstruction

Energy Technology Data Exchange (ETDEWEB)

Kaasalainen, Touko; Lampinen, Anniina [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); University of Helsinki, Department of Physics, Helsinki (Finland); Palmu, Kirsi [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); School of Science, Aalto University, Department of Biomedical Engineering and Computational Science, Helsinki (Finland); Reijonen, Vappu; Kortesniemi, Mika [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); Leikola, Junnu [University of Helsinki and Helsinki University Hospital, Department of Plastic Surgery, Helsinki (Finland); Kivisaari, Riku [University of Helsinki and Helsinki University Hospital, Department of Neurosurgery, Helsinki (Finland)

2015-09-15

Medical professionals need to exercise particular caution when developing CT scanning protocols for children who require multiple CT studies, such as those with craniosynostosis. To evaluate the utility of ultra-low-dose CT protocols with model-based iterative reconstruction techniques for craniosynostosis imaging. We scanned two pediatric anthropomorphic phantoms with a 64-slice CT scanner using different low-dose protocols for craniosynostosis. We measured organ doses in the head region with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Numerical simulations served to estimate organ and effective doses. We objectively and subjectively evaluated the quality of images produced by adaptive statistical iterative reconstruction (ASiR) 30%, ASiR 50% and Veo (all by GE Healthcare, Waukesha, WI). Image noise and contrast were determined for different tissues. Mean organ dose with the newborn phantom was decreased up to 83% compared to the routine protocol when using ultra-low-dose scanning settings. Similarly, for the 5-year phantom the greatest radiation dose reduction was 88%. The numerical simulations supported the findings with MOSFET measurements. The image quality remained adequate with Veo reconstruction, even at the lowest dose level. Craniosynostosis CT with model-based iterative reconstruction could be performed with a 20-μSv effective dose, corresponding to the radiation exposure of plain skull radiography, without compromising required image quality. (orig.)

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

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)

Development and validation of two phantoms for quality control in cone-beam CT

International Nuclear Information System (INIS)

Gomes B, W. O.

2016-10-01

The cone beam computed tomography (CBCT) was introduced into the market in the late 90 s and being a relatively new technology, also no well-established quality control protocols. There are currently projects to standardize the use of CBCT. The SEDENTEXCT project was created with the goal of developing guidelines for CBCT, including the development of a phantom for quality control it is proposed. This study aimed at the development and validation of the models of phantom: CQ_IFBA_01 e CQ_IFBA_02, the first filled with water and the second fully with solid structure in PMMA. Both models allow, otherwise the European phantom - SEDENTEXCT, its use in various models of CBCT, independent of the size of the field of view. The two phantoms used to evaluate seven parameters of quality control are: intensity or average value of pixels of five different plastics, signal to noise ratio, resolution, low contrast, spatial resolution, the accuracy of distances on the z axis, the geometric distortion and image uniformity. The spatial resolution is a critical parameter that differs significantly from the other types of scan, and in these two phantom can be evaluated by two different methods: MTF obtained by Fourier transformation of the function LSF (line spread function) and/or by analysis visual image to a pattern of bars up to 16 pl/cm. Validation was performed in three models CBCT: Kodak 9000, i-CAT Classical and Orthophos XG 3-dimensional. All imaging protocols were characterized dosimetric ally with solid state sensors to correlate with the perfect operation. These models were selected by different manufacturers have different characteristics as FOV, maximum voltage, slice thickness and patient positioning mode. The two of phantom models were viable and also showed compliance with the specifications and data available in the literature. We conclude the feasibility of the two phantom models, and model option will be linked to the practicality positioning equipment. (Author)

Development and validation of two phantoms for quality control in cone-beam CT

Energy Technology Data Exchange (ETDEWEB)

Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho 40301-015, Salvador de Bahia (Brazil)

2016-10-15

The cone beam computed tomography (CBCT) was introduced into the market in the late 90 s and being a relatively new technology, also no well-established quality control protocols. There are currently projects to standardize the use of CBCT. The SEDENTEXCT project was created with the goal of developing guidelines for CBCT, including the development of a phantom for quality control it is proposed. This study aimed at the development and validation of the models of phantom: CQ{sub I}FBA{sub 0}1 e CQ{sub I}FBA{sub 0}2, the first filled with water and the second fully with solid structure in PMMA. Both models allow, otherwise the European phantom - SEDENTEXCT, its use in various models of CBCT, independent of the size of the field of view. The two phantoms used to evaluate seven parameters of quality control are: intensity or average value of pixels of five different plastics, signal to noise ratio, resolution, low contrast, spatial resolution, the accuracy of distances on the z axis, the geometric distortion and image uniformity. The spatial resolution is a critical parameter that differs significantly from the other types of scan, and in these two phantom can be evaluated by two different methods: MTF obtained by Fourier transformation of the function LSF (line spread function) and/or by analysis visual image to a pattern of bars up to 16 pl/cm. Validation was performed in three models CBCT: Kodak 9000, i-CAT Classical and Orthophos XG 3-dimensional. All imaging protocols were characterized dosimetric ally with solid state sensors to correlate with the perfect operation. These models were selected by different manufacturers have different characteristics as FOV, maximum voltage, slice thickness and patient positioning mode. The two of phantom models were viable and also showed compliance with the specifications and data available in the literature. We conclude the feasibility of the two phantom models, and model option will be linked to the practicality positioning

Comparison of methods for individualized astronaut organ dosimetry: Morphometry-based phantom library versus body contour autoscaling of a reference phantom

Science.gov (United States)

Sands, Michelle M.; Borrego, David; Maynard, Matthew R.; Bahadori, Amir A.; Bolch, Wesley E.

2017-11-01

One of the hazards faced by space crew members in low-Earth orbit or in deep space is exposure to ionizing radiation. It has been shown previously that while differences in organ-specific and whole-body risk estimates due to body size variations are small for highly-penetrating galactic cosmic rays, large differences in these quantities can result from exposure to shorter-range trapped proton or solar particle event radiations. For this reason, it is desirable to use morphometrically accurate computational phantoms representing each astronaut for a risk analysis, especially in the case of a solar particle event. An algorithm was developed to automatically sculpt and scale the UF adult male and adult female hybrid reference phantom to the individual outer body contour of a given astronaut. This process begins with the creation of a laser-measured polygon mesh model of the astronaut's body contour. Using the auto-scaling program and selecting several anatomical landmarks, the UF adult male or female phantom is adjusted to match the laser-measured outer body contour of the astronaut. A dosimetry comparison study was conducted to compare the organ dose accuracy of both the autoscaled phantom and that based upon a height-weight matched phantom from the UF/NCI Computational Phantom Library. Monte Carlo methods were used to simulate the environment of the August 1972 and February 1956 solar particle events. Using a series of individual-specific voxel phantoms as a local benchmark standard, autoscaled phantom organ dose estimates were shown to provide a 1% and 10% improvement in organ dose accuracy for a population of females and males, respectively, as compared to organ doses derived from height-weight matched phantoms from the UF/NCI Computational Phantom Library. In addition, this slight improvement in organ dose accuracy from the autoscaled phantoms is accompanied by reduced computer storage requirements and a more rapid method for individualized phantom generation

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

Toxicology Analysis of Tissue-Mimicking Phantom Made From Gelatin

Science.gov (United States)

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.

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

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)

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.

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

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.

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)

Phantoms in artists: the lost limbs of Blaise Cendrars,Arthur Rimbaud, and Paul Wittgenstein.

Science.gov (United States)

Tatu, Laurent; Bogousslavsky, Julien; Boller, François

2014-01-01

There have been an increasing number of reports of postamputation pain and problems linked to phantom limbs over recent years, particularly in relation to war-related amputations. These problems, which are often poorly understood and considered rather mysterious, are still relevant because they are difficult to treat medically. Functional neuroimaging techniques now enable us to better understand their pathophysiology and to consider new rehabilitation techniques. Phantom limbs have often been a source of inspiration to writers, particularly in the period following the First World War, which was responsible for thousands of amputees. Some artists have suffered from postamputation complications themselves and have expressed them through their artistic works. Blaise Cendrars (1887-1961), one of the greatest authors of the twentieth century, suffered from stump pain and phantom limb phenomena for almost half a century following the amputation of his right arm during the First World War. He suffered from these phenomena until the end of his life and his literary work and personal correspondence are peppered with references to them. Arthur Rimbaud (1854-1891), one of the most famous poets in world literature, developed severe stump pain after his right leg was amputated due to a tumor. He survived for only six months after the procedure but left behind an account of the pain he experienced in correspondence to his family. The famous pianist Paul Wittgenstein (1887-1961), whose right arm was amputated during the First World War, became a famous left-handed concert pianist. The phantom movements of his right hand helped him to develop the dexterity of his left hand. The impact on the artistic life of these three men provides an original illustration of the various postamputation complications, specifically phantom limbs, stump pain, and moving phantom.

Phantom cosmology without Big Rip singularity

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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.

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.

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)

Concept design and simulation study on a "phantom" anvil for circular stapler.

Science.gov (United States)

Rulli, Francesco; Kartheuser, Alex; Amirhassankhani, Sasan; Mourad, Michel; Stefani, Mario; de Ferrá Aureli, Andrés; Sileri, Pierpaolo; Valentini, Pier Paolo

2015-04-01

Complications and challenges arising from the intraoperative double-stapling technique are seldom reported in colorectal surgery literature. Partial or full-thickness rectal injuries can occur during the introduction and the advancement of the circular stapler along the upper rectum. The aim of this study is to address some of these issues by designing and optimizing a "phantom" anvil manufactured to overcome difficulties throughout the rectal introduction and advancement of the circular stapler for the treatment of benign and malignant colon disease. The design of the "phantom" anvil has been performed using computer-aided modeling techniques, finite element investigations, and 2 essential keynotes in mind. The first one is the internal shape of the anvil, which is used for the connection to the gun. The second is the shape of the cap, which makes possible the insertion of the gun through the rectum. The "phantom" anvil has 2 functional requirements, which have been taken into account. The design has been optimized to avoid colorectal injuries, neoplastic dissemination (ie, mechanical seeding) and to reduce the fecal contamination. Numerical simulations show that a right combination of both top and bottom fillet radii of the shape of the anvil can reduce the stress for the considered anatomic configuration of >90%. Both the fillet radii at the top and the bottom of the device influence the local stress of the colon rectum. A dismountable device, which is used only for the insertion and advancement of the stapler, allows a dedicated design of its shape, keeping the remainder of the stapler unmodified. Computer-aided simulations are useful to perform numerical investigations to optimize the design of this auxiliary part for both the safety of the patient and the ease of the stapler advancement through the rectum.

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.

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.

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.

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

WE-D-303-00: Computational Phantoms

Energy Technology Data Exchange (ETDEWEB)

Lewis, John [Duke University Medical Center, Durham, NC (United States); Brigham and Women’s Hospital and Dana-Farber Cancer Institute, Boston, MA (United States)

2015-06-15

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems.

WE-D-303-00: Computational Phantoms

International Nuclear Information System (INIS)

Lewis, John

2015-01-01

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems

[Mirror, mirror of the wall: mirror therapy in the treatment of phantom limbs and phantom limb pain].

Science.gov (United States)

Casale, Roberto; Furnari, Anna; Lamberti, Raul Coelho; Kouloulas, Efthimios; Hagenberg, Annegret; Mallik, Maryam

2015-01-01

Phantom limb and phantom limb pain control are pivotal points in the sequence of intervention to bring the amputee to functional autonomy. The alterations of perception and sensation, the pain of the residual limb and the phantom limb are therefore aspects of amputation that should be taken into account in the "prise en charge" of these patients. Within the more advanced physical therapies to control phantom and phantom limb pain there is the use of mirrors (mirror therapy). This article willfocus on its use and on the possible side effects induced by the lack of patient selection and a conflict of body schema restoration through mirror therapy with concurrent prosthetic training and trauma acceptance. Advice on the need to select patients before treatment decisions, with regard to their psychological as well as clinical profile (including time since amputation and clinical setting), and the need to be aware of the possible adverse effects matching different and somehow conflicting therapeutic approaches, are put forward. Thus a coordinated sequence of diagnostic, prognostic and therapeutic procedures carried out by an interdisciplinary rehabilitation team that works globally on all patients' problems is fundamental in the management of amputees and phantom limb pain. Further studies and the development of a multidisciplinary network to study this and other applications of mirror therapy are needed.

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.

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.)

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)

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

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.

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.)

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

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...

Apparent motion perception in lower limb amputees with phantom sensations: "obstacle shunning" and "obstacle tolerance".

Science.gov (United States)

Saetta, Gianluca; Grond, Ilva; Brugger, Peter; Lenggenhager, Bigna; Tsay, Anthony J; Giummarra, Melita J

2018-03-21

Phantom limbs are the phenomenal persistence of postural and sensorimotor features of an amputated limb. Although immaterial, their characteristics can be modulated by the presence of physical matter. For instance, the phantom may disappear when its phenomenal space is invaded by objects ("obstacle shunning"). Alternatively, "obstacle tolerance" occurs when the phantom is not limited by the law of impenetrability and co-exists with physical objects. Here we examined the link between this under-investigated aspect of phantom limbs and apparent motion perception. The illusion of apparent motion of human limbs involves the perception that a limb moves through or around an object, depending on the stimulus onset asynchrony (SOA) for the two images. Participants included 12 unilateral lower limb amputees matched for obstacle shunning (n = 6) and obstacle tolerance (n = 6) experiences, and 14 non-amputees. Using multilevel linear models, we replicated robust biases for short perceived trajectories for short SOA (moving through the object), and long trajectories (circumventing the object) for long SOAs in both groups. Importantly, however, amputees with obstacle shunning perceived leg stimuli to predominantly move through the object, whereas amputees with obstacle tolerance perceived leg stimuli to predominantly move around the object. That is, in people who experience obstacle shunning, apparent motion perception of lower limbs was not constrained to the laws of impenetrability (as the phantom disappears when invaded by objects), and legs can therefore move through physical objects. Amputees who experience obstacle tolerance, however, had stronger solidity constraints for lower limb apparent motion, perhaps because they must avoid co-location of the phantom with physical objects. Phantom limb experience does, therefore, appear to be modulated by intuitive physics, but not in the same way for everyone. This may have important implications for limb experience post

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

International Nuclear Information System (INIS)

Pirayesh Islamian, J.; Bahreyni Toosi, M. T.; Momennezhad, M.; Naseri, Sh.; Ljungberg, M.

2012-01-01

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. 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. 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. 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 characteristics when a new similar clinical SPECT procedure is being simulated.

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

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)

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

Development and evaluation of a phantom for multi-purpose dosimetry in intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Jeong, Hae Sun; Kim, Chan Hyeong; Park, Joo Hwan; Han, Young Yih; Kum, O Yeon

2011-01-01

A LEGO-type multi-purpose dosimetry phantom was developed for intensity-modulated radiation therapy (IMRT), which requires various types of challenging dosimetry. Polystyrene, polyethylene, polytetrafluoroethylene (PTFE), and polyurethane foam (PU-F) were selected to represent muscle, fat, bone, and lung tissue, respectively, after considering the relevant mass densities, elemental compositions, effective atomic numbers, and photon interaction coefficients. The phantom, which is composed of numerous small pieces that are similar to LEGO blocks, provides dose and dose distribution measurements in homogeneous and heterogeneous media. The phantom includes dosimeter holders for several types of dosimeters that are frequently used in IMRT dosimetry. An ion chamber and a diode detector were used to test dosimetry in heterogeneous media under radiation fields of various sizes. The data that were measured using these dosimeters were in disagreement when the field sizes were smaller than 1.5 x 1.5 cm 2 for polystyrene and PTFE, or smaller than 3 x 3 cm 2 for an air cavity. The discrepancy was as large as 41% for the air cavity when the field size was 0.7 x 0.7 cm 2 , highlighting one of the challenges of IMRT small field dosimetry. The LEGO-type phantom is also very useful for two-dimensional dosimetry analysis, which elucidates the electronic dis-equilibrium phenomena on or near the heterogeneity boundaries

Development and evaluation of a phantom for multi-purpose dosimetry in intensity-modulated radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae Sun; Kim, Chan Hyeong [Hanyang University, Seoul (Korea, Republic of); Park, Joo Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, Young Yih [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kum, O Yeon [Yonsei University College of Medicine, Seoul (Korea, Republic of)

2011-08-15

A LEGO-type multi-purpose dosimetry phantom was developed for intensity-modulated radiation therapy (IMRT), which requires various types of challenging dosimetry. Polystyrene, polyethylene, polytetrafluoroethylene (PTFE), and polyurethane foam (PU-F) were selected to represent muscle, fat, bone, and lung tissue, respectively, after considering the relevant mass densities, elemental compositions, effective atomic numbers, and photon interaction coefficients. The phantom, which is composed of numerous small pieces that are similar to LEGO blocks, provides dose and dose distribution measurements in homogeneous and heterogeneous media. The phantom includes dosimeter holders for several types of dosimeters that are frequently used in IMRT dosimetry. An ion chamber and a diode detector were used to test dosimetry in heterogeneous media under radiation fields of various sizes. The data that were measured using these dosimeters were in disagreement when the field sizes were smaller than 1.5 x 1.5 cm{sup 2} for polystyrene and PTFE, or smaller than 3 x 3 cm{sup 2} for an air cavity. The discrepancy was as large as 41% for the air cavity when the field size was 0.7 x 0.7 cm{sup 2}, highlighting one of the challenges of IMRT small field dosimetry. The LEGO-type phantom is also very useful for two-dimensional dosimetry analysis, which elucidates the electronic dis-equilibrium phenomena on or near the heterogeneity boundaries

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)

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

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

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

Theoretical assessment of whole body counting performances using numerical phantoms of different gender and sizes.

Science.gov (United States)

Marzocchi, O; Breustedt, B; Mostacci, D; Zankl, M; Urban, M

2011-03-01

A goal of whole body counting (WBC) is the estimation of the total body burden of radionuclides disregarding the actual position within the body. To achieve the goal, the detectors need to be placed in regions where the photon flux is as independent as possible from the distribution of the source. At the same time, the detectors need high photon fluxes in order to achieve better efficiency and lower minimum detectable activities. This work presents a method able to define the layout of new WBC systems and to study the behaviour of existing ones using both detection efficiency and its dependence on the position of the source within the body of computational phantoms.

Theoretical assessment of whole body counting performances using numerical phantoms of different gender and sizes

International Nuclear Information System (INIS)

Marzocchi, O.; Breustedt, B.; Mostacci, D.; Zankl, M.; Urban, M.

2011-01-01

A goal of whole body counting (WBC) is the estimation of the total body burden of radionuclides disregarding the actual position within the body. To achieve the goal, the detectors need to be placed in regions where the photon flux is as independent as possible from the distribution of the source. At the same time, the detectors need high photon fluxes in order to achieve better efficiency and lower minimum detectable activities. This work presents a method able to define the layout of new WBC systems and to study the behaviour of existing ones using both detection efficiency and its dependence on the position of the source within the body of computational phantoms. (authors)

Paul Wittgenstein's right arm and his phantom: the saga of a famous concert pianist and his amputation.

Science.gov (United States)

Boller, François; Bogousslavsky, Julien

2015-01-01

Reports of postamputation pain and problems linked to phantom limbs have increased in recent years, particularly in relation to war-related amputations. These problems are still poorly understood and are considered rather mysterious, and they are difficult to treat. In addition, they may shed light on brain physiology and neuropsychology. Functional neuroimaging techniques now enable us to better understand their pathophysiology and to consider new rehabilitation techniques. Several artists have suffered from postamputation complications and this has influenced not only their personal life but also their artistic work. Paul Wittgenstein (1887-1961), a pianist whose right arm was amputated during the First World War, became a famous left-handed concert performer. His case provides insight into Post-World War I musical and political history. More specifically, the impact on the artistic life of this pianist illustrates various postamputation complications, such as phantom limb, stump pain, and especially moving phantom. The phantom movements of his right hand helped him develop the dexterity of his left hand. Wittgenstein played piano works that were written especially for him (the most famous being Ravel's Concerto for the Left Hand) and composed some of his own. Additionally, several famous composers had previously written for the left hand. © 2015 Elsevier B.V. All rights reserved.

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. ...

Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas.

Science.gov (United States)

van Wyk, Marnus J; Bingle, Marianne; Meyer, Frans J C

2005-09-01

International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines. (c) 2005 Wiley-Liss, Inc.

Energy Efficient Resource Allocation for Phantom Cellular Networks

KAUST Repository

Abdelhady, Amr

2016-04-01

Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Meanwhile, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for the recently proposed two-tier network architecture known as phantom cellular networks. The optimization framework includes both EE and SE. First, we consider sparsely deployed cells experiencing negligible interference and assume perfect channel state information (CSI). For this setting, we propose an algorithm that finds the SE and EE resource allocation strategies. Then, we compare the performance of both design strategies versus number of users, and phantom cells share of the total available resource units (RUs). We aim to investigate the effect of some system parameters to achieve improved SE performance at a non-significant loss in EE performance, or vice versa. It is found that increasing phantom cells share of RUs decreases the SE performance loss due to EE optimization when compared with the optimized SE performance. Second, we consider the densely deployed phantom cellular networks and model the EE optimization problem having into consideration the inevitable interference and imperfect channel estimation. To this end, we propose three resource allocation strategies aiming at optimizing the EE performance metric of this network. Furthermore, we investigate the effect of changing some of the system parameters on the performance of the proposed strategies, such as phantom cells share of RUs, number of deployed phantom cells within a macro cell coverage, number of pilots and the maximum power available for transmission by the phantom cells BSs. It is found that increasing the number of pilots deteriorates the EE performance of the whole setup, while increasing maximum power available for phantom cells transmissions reduces the EE of the whole setup in a

[Psychotherapies for the Treatment of Phantom Limb Pain].

Science.gov (United States)

Cárdenas, Katherine; Aranda, Mariana

The phantom limb pain has been described as a condition in which patients experience a feeling of itching, spasm or pain in a limb or body part that has been previously amputated. Such pain can be induced by a conflict between the representation of the visual and proprioceptive feedback of the previously healthy limb. The phantom limb pain occurs in at least 42 to 90% of amputees. Regular drug treatment of phantom limb pain is almost never effective. A systematic review of the literature was conducted in Medline and Cochrane using the MESH terms "phantom limb pain" and "psychotherapy", published in the last 10 years, in English and Spanish, finding 49 items. After reviewing the abstracts, 25 articles were excluded for not being related to the objective of the research. Additionally cross references of included articles and literature were reviewed. To describe the psychotherapies used in the management of phantom limb pain, their effectiveness and clinical application reported in the literature. The mechanisms underlying phantom limb pain were initially explained, as were the published studies on the usefulness of some psychotherapies such as mirror visual feedback and immersive virtual reality, visual imagery, desensitization and reprocessing eye movements and hypnosis. The phantom limb pain is a complex syndrome that requires pharmacological and psychotherapeutic intervention. The psychotherapies that have been used the most as adjuvants in the treatment of phantom limb pain are mirror visual feedback, desensitization and reprocessing eye movements, imagery and hypnosis. Studies with more representative samples, specifically randomized trials are required. Copyright © 2016 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

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....

SU-E-I-94: Automated Image Quality Assessment of Radiographic Systems Using An Anthropomorphic Phantom

International Nuclear Information System (INIS)

Wells, J; Wilson, J; Zhang, Y; Samei, E; Ravin, Carl E.

2014-01-01

Purpose: In a large, academic medical center, consistent radiographic imaging performance is difficult to routinely monitor and maintain, especially for a fleet consisting of multiple vendors, models, software versions, and numerous imaging protocols. Thus, an automated image quality control methodology has been implemented using routine image quality assessment with a physical, stylized anthropomorphic chest phantom. Methods: The “Duke” Phantom (Digital Phantom 07-646, Supertech, Elkhart, IN) was imaged twice on each of 13 radiographic units from a variety of vendors at 13 primary care clinics. The first acquisition used the clinical PA chest protocol to acquire the post-processed “FOR PRESENTATION” image. The second image was acquired without an antiscatter grid followed by collection of the “FOR PROCESSING” image. Manual CNR measurements were made from the largest and thickest contrast-detail inserts in the lung, heart, and abdominal regions of the phantom in each image. An automated image registration algorithm was used to estimate the CNR of the same insert using similar ROIs. Automated measurements were then compared to the manual measurements. Results: Automatic and manual CNR measurements obtained from “FOR PRESENTATION” images had average percent differences of 0.42%±5.18%, −3.44%±4.85%, and 1.04%±3.15% in the lung, heart, and abdominal regions, respectively; measurements obtained from “FOR PROCESSING” images had average percent differences of -0.63%±6.66%, −0.97%±3.92%, and −0.53%±4.18%, respectively. The maximum absolute difference in CNR was 15.78%, 10.89%, and 8.73% in the respective regions. In addition to CNR assessment of the largest and thickest contrast-detail inserts, the automated method also provided CNR estimates for all 75 contrast-detail inserts in each phantom image. Conclusion: Automated analysis of a radiographic phantom has been shown to be a fast, robust, and objective means for assessing radiographic

The UF family of reference hybrid phantoms for computational radiation dosimetry

International Nuclear Information System (INIS)

Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L; Bolch, Wesley E

2010-01-01

Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms-those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR(TM). NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros(TM). The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference

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

Measurement of TLD Albedo response on various calibration phantoms

International Nuclear Information System (INIS)

Momose, T.; Tsujimura, N.; Shinohara, K.; Ishiguro, H.; Nakamura, T.

1996-01-01

The International Commission on Radiation Units and Measurements (ICRU) has recommended that individual dosemeter should be calibrated on a suitable phantom and has pointed out that the calibration factor of a neutron dosemeter is strongly influenced by the the exact size and shape of the body and the phantom to which the dosemeter is attached. As the principle of an albedo type thermoluminescent personal dosemeter (albedo TLD) is essentially based on a detection of scattered and moderated neutron from a human body, the sensitivity of albedo TLD is strongly influenced by the incident neutron energy and the calibration phantom. (1) Therefore for albedo type thermoluminescent personal dosemeter (albedo TLD), the information of neutron albedo response on the calibration phantom is important for appropriate dose estimation. In order to investigate the effect of phantom type on the reading of the albedo TLD, measurement of the TLD energy response and angular response on some typical calibration phantoms was performed using dynamitron accelerator and 252 Cf neutron source. (author)

Agency over Phantom Limb Enhanced by Short-Term Mirror Therapy.

Science.gov (United States)

Imaizumi, Shu; Asai, Tomohisa; Koyama, Shinichi

2017-01-01

Most amputees experience phantom limb, whereby they feel that the amputated limb is still present. In some cases, these experiences include pain that can be alleviated by "mirror therapy." Mirror therapy consists of superimposing a mirrored image of the moving intact limb onto the phantom limb. This therapy provides a closed loop between the motor command to the amputated limb and its predicted visual feedback. This loop is also involved in the sense of agency, a feeling of controlling one's own body. However, it is unclear how mirror therapy is related to the sense of agency over a phantom limb. Using mirror therapy, we investigated phantom limb pain and the senses of agency and ownership (i.e., a feeling of having one's own body) of the phantom limb. Nine upper-limb amputees, five of whom reported recent phantom limb pain, underwent a single 15-min trial of mirror therapy. Before and after the trial, the participants completed a questionnaire regarding agency, ownership, and pain related to their phantom limb. They reported that the sense of agency over the phantom limb increased following the mirror therapy trial, while the ownership slightly increased but not as much as did the agency. The reported pain did not change; that is, it was comparably mild before and after the trial. These results suggest that short-term mirror therapy can, at least transiently, selectively enhance the sense of agency over a phantom limb, but may not alleviate phantom limb pain.

Technical Note: Characterization of custom 3D printed multimodality imaging phantoms

International Nuclear Information System (INIS)

Bieniosek, Matthew F.; Lee, Brian J.; Levin, Craig S.

2015-01-01

Purpose: Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial “Micro Deluxe” phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. Methods: CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results: Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. Conclusions: This work shows that 3D printed

Technical Note: Characterization of custom 3D printed multimodality imaging phantoms

Energy Technology Data Exchange (ETDEWEB)

Bieniosek, Matthew F. [Department of Electrical Engineering, Stanford University, 350 Serra Mall, Stanford, California 94305 (United States); Lee, Brian J. [Department of Mechanical Engineering, Stanford University, 440 Escondido Mall, Stanford, California 94305 (United States); Levin, Craig S., E-mail: cslevin@stanford.edu [Departments of Radiology, Physics, Bioengineering and Electrical Engineering, Stanford University, 300 Pasteur Dr., Stanford, California 94305-5128 (United States)

2015-10-15

Purpose: Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial “Micro Deluxe” phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. Methods: CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results: Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. Conclusions: This work shows that 3D printed

Technical Note: Characterization of custom 3D printed multimodality imaging phantoms.

Science.gov (United States)

Bieniosek, Matthew F; Lee, Brian J; Levin, Craig S

2015-10-01

Imaging phantoms are important tools for researchers and technicians, but they can be costly and difficult to customize. Three dimensional (3D) printing is a widely available rapid prototyping technique that enables the fabrication of objects with 3D computer generated geometries. It is ideal for quickly producing customized, low cost, multimodal, reusable imaging phantoms. This work validates the use of 3D printed phantoms by comparing CT and PET scans of a 3D printed phantom and a commercial "Micro Deluxe" phantom. This report also presents results from a customized 3D printed PET/MRI phantom, and a customized high resolution imaging phantom with sub-mm features. CT and PET scans of a 3D printed phantom and a commercial Micro Deluxe (Data Spectrum Corporation, USA) phantom with 1.2, 1.6, 2.4, 3.2, 4.0, and 4.8 mm diameter hot rods were acquired. The measured PET and CT rod sizes, activities, and attenuation coefficients were compared. A PET/MRI scan of a custom 3D printed phantom with hot and cold rods was performed, with photon attenuation and normalization measurements performed with a separate 3D printed normalization phantom. X-ray transmission scans of a customized two level high resolution 3D printed phantom with sub-mm features were also performed. Results show very good agreement between commercial and 3D printed micro deluxe phantoms with less than 3% difference in CT measured rod diameter, less than 5% difference in PET measured rod diameter, and a maximum of 6.2% difference in average rod activity from a 10 min, 333 kBq/ml (9 μCi/ml) Siemens Inveon (Siemens Healthcare, Germany) PET scan. In all cases, these differences were within the measurement uncertainties of our setups. PET/MRI scans successfully identified 3D printed hot and cold rods on PET and MRI modalities. X-ray projection images of a 3D printed high resolution phantom identified features as small as 350 μm wide. This work shows that 3D printed phantoms can be functionally equivalent to

Design of a tracked ultrasound calibration phantom made of LEGO bricks

Science.gov (United States)

Walsh, Ryan; Soehl, Marie; Rankin, Adam; Lasso, Andras; Fichtinger, Gabor

2014-03-01

PURPOSE: Spatial calibration of tracked ultrasound systems is commonly performed using precisely fabricated phantoms. Machining or 3D printing has relatively high cost and not easily available. Moreover, the possibilities for modifying the phantoms are very limited. Our goal was to find a method to construct a calibration phantom from affordable, widely available components, which can be built in short time, can be easily modified, and provides comparable accuracy to the existing solutions. METHODS: We designed an N-wire calibration phantom made of LEGO® bricks. To affirm the phantom's reproducibility and build time, ten builds were done by first-time users. The phantoms were used for a tracked ultrasound calibration by an experienced user. The success of each user's build was determined by the lowest root mean square (RMS) wire reprojection error of three calibrations. The accuracy and variance of calibrations were evaluated for the calibrations produced for various tracked ultrasound probes. The proposed model was compared to two of the currently available phantom models for both electromagnetic and optical tracking. RESULTS: The phantom was successfully built by all ten first-time users in an average time of 18.8 minutes. It cost approximately $10 CAD for the required LEGO® bricks and averaged a 0.69mm of error in the calibration reproducibility for ultrasound calibrations. It is one third the cost of similar 3D printed phantoms and takes much less time to build. The proposed phantom's image reprojections were 0.13mm more erroneous than those of the highest performing current phantom model The average standard deviation of multiple 3D image reprojections differed by 0.05mm between the phantoms CONCLUSION: It was found that the phantom could be built in less time, was one third the cost, compared to similar 3D printed models. The proposed phantom was found to be capable of producing equivalent calibrations to 3D printed phantoms.

Radiation dose verification using real tissue phantom in modern radiotherapy techniques

International Nuclear Information System (INIS)

Gurjar, Om Prakash; Mishra, S.P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima

2014-01-01

In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as 'head phantom' and goat meat as 'tissue phantom'. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. (author)

Radiation dose verification using real tissue phantom in modern radiotherapy techniques

Directory of Open Access Journals (Sweden)

Om Prakash Gurjar

2014-01-01

Full Text Available In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as "head phantom" and goat meat as "tissue phantom". The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD: 0.74, 2.36 (SD: 0.77, 3.62 (SD: 1.05, and 3.31 (SD: 0.78 for three-dimensional conformal radiotherapy (3DCRT (head phantom, intensity modulated radiotherapy (IMRT; head phantom, 3DCRT (tissue phantom, and IMRT (tissue phantom, respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%, but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body.

NURBS-based 3-d anthropomorphic computational phantoms for radiation dosimetry applications

International Nuclear Information System (INIS)

Lee, Choonsik; Lodwick, Daniel; Lee, Choonik; Bolch, Wesley E.

2007-01-01

Computational anthropomorphic phantoms are computer models used in the evaluation of absorbed dose distributions within the human body. Currently, two classes of the computational phantoms have been developed and widely utilised for dosimetry calculation: (1) stylized (equation-based) and (2) voxel (image-based) phantoms describing human anatomy through the use of mathematical surface equations and 3-D voxel matrices, respectively. However, stylized phantoms have limitations in defining realistic organ contours and positioning as compared to voxel phantoms, which are themselves based on medical images of human subjects. In turn, voxel phantoms that have been developed through medical image segmentation have limitations in describing organs that are presented in low contrast within either magnetic resonance or computed tomography image. The present paper reviews the advantages and disadvantages of these existing classes of computational phantoms and introduces a hybrid approach to a computational phantom construction based on non-uniform rational B-Spline (NURBS) surface animation technology that takes advantage of the most desirable features of the former two phantom types. (authors)

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

Beyond body experiences: phantom limbs, pain and the locus of sensation.

Science.gov (United States)

Wade, Nicholas J

2009-02-01

Reports of perceptual experiences are found throughout history. However, the phenomena considered worthy of note have not been those that nurture our survival (the veridical features of perception) but the oddities or departures from the common and commonplace accuracies of perception. Some oddities (like afterimages) could be experienced by everyone, whereas others were idiosyncratic. Such phenomena were often given a paranormal interpretation before they were absorbed into the normal science of the day. This sequence is examined historically in the context of beyond body experiences or phantom limbs. The experience of sensations in lost body parts provides an example of the ways in which novel phenomena can be interpreted. The first phase of description probably occurred in medieval texts and was often associated with accounts of miraculous reconnection. Ambroise Paré (1510-1590) initiated medical interest in this intriguing aspect of perception, partly because more of his patients survived the trauma of surgery. Description is followed by attempts to incorporate the phenomenon into the body of extant theory. René Descartes (1596-1650) integrated sensations in amputated limbs into his dualist theory of mind, and used the phenomenon to support the unity of the mind in comparison to the fragmented nature of bodily sensations. Others, like William Porterfield (ca. 1696-1771), did not consider the phenomenon as illusory and interpreted it in terms of other projective features of perception. Finally, the phenomenon is accepted and utilized to gain more insights into the functioning of the senses and the brain. The principal features of phantom limbs were well known before they were given that name in the 19th century. Despite the puzzles they still pose, these phantoms continue to provide perception with some potent concepts: the association with theories of pain has loosened the link with peripheral stimulation and emphasis on the phenomenal dimension has slackened

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.)

Magnetoencephalography Phantom Comparison and Validation: Hospital Universiti Sains Malaysia (HUSM) Requisite.

Science.gov (United States)

Omar, Hazim; Ahmad, Alwani Liyan; Hayashi, Noburo; Idris, Zamzuri; Abdullah, Jafri Malin

2015-12-01

Magnetoencephalography (MEG) has been extensively used to measure small-scale neuronal brain activity. Although it is widely acknowledged as a sensitive tool for deciphering brain activity and source localisation, the accuracy of the MEG system must be critically evaluated. Typically, on-site calibration with the provided phantom (Local phantom) is used. However, this method is still questionable due to the uncertainty that may originate from the phantom itself. Ideally, the validation of MEG data measurements would require cross-site comparability. A simple method of phantom testing was used twice in addition to a measurement taken with a calibrated reference phantom (RefPhantom) obtained from Elekta Oy of Helsinki, Finland. The comparisons of two main aspects were made in terms of the dipole moment (Qpp) and the difference in the dipole distance from the origin (d) after the tests of statistically equal means and variance were confirmed. The result of Qpp measurements for the LocalPhantom and RefPhantom were 978 (SD24) nAm and 988 (SD32) nAm, respectively, and were still optimally within the accepted range of 900 to 1100 nAm. Moreover, the shifted d results for the LocalPhantom and RefPhantom were 1.84 mm (SD 0.53) and 2.14 mm (SD 0.78), respectively, and these values were below the maximum acceptance range of within 5.0 mm of the nominal dipole location. The Local phantom seems to outperform the reference phantom as indicated by the small standard error of the former (SE 0.094) compared with the latter (SE 0.138). The result indicated that HUSM MEG system was in excellent working condition in terms of the dipole magnitude and localisation measurements as these values passed the acceptance limits criteria of the phantom test.

Experimental and computational development of a natural breast phantom for dosimetry studies

International Nuclear Information System (INIS)

Nogueira, Luciana B.; Campos, Tarcisio P.R.

2013-01-01

This paper describes the experimental and computational development of a natural breast phantom, anthropomorphic and anthropometric for studies in dosimetry of brachytherapy and teletherapy of breast. The natural breast phantom developed corresponding to fibroadipose breasts of women aged 30 to 50 years, presenting radiographically medium density. The experimental breast phantom was constituted of three tissue-equivalents (TE's): glandular TE, adipose TE and skin TE. These TE's were developed according to chemical composition of human breast and present radiological response to exposure. Completed the construction of experimental breast phantom this was mounted on a thorax phantom previously developed by the research group NRI/UFMG. Then the computational breast phantom was constructed by performing a computed tomography (CT) by axial slices of the chest phantom. Through the images generated by CT a computational model of voxels of the thorax phantom was developed by SISCODES computational program, being the computational breast phantom represented by the same TE's of the experimental breast phantom. The images generated by CT allowed evaluating the radiological equivalence of the tissues. The breast phantom is being used in studies of experimental dosimetry both in brachytherapy as in teletherapy of breast. Dosimetry studies by MCNP-5 code using the computational model of the phantom breast are in progress. (author)

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.

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....

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

Science.gov (United States)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

New format for storage of voxel phantom, and exposure computer model EGS4/MAX to EGSnrc/MASH update

International Nuclear Information System (INIS)

Leal Neto, Viriato; Vieira, Jose W.; Lima, Fernando R.A.; Lima, Lindeval F.

2011-01-01

In order to estimate the dosage absorbed by those subjected to ionizing radiation, it is necessary to perform simulations using the exposure computational model (ECM). Such models are consists essentially of an anthropomorphic phantom and a Monte Carlo code (MC). The conjunction of a voxel phantom of the MC code is a complex process and often results in solving a specific problem. This is partly due to the way the phantom voxel is stored on a computer. It is usually required a substantial amount of space to store a static representation of the human body and also a significant amount of memory for reading and processing a given simulation. This paper presents a new way to store data concerning the geometry irradiated (similar to the technique of repeated structures used in the geometry of MCNP code), reducing by 52% the disk space required for storage when compared to the previous format applied by Grupo de Dosimetria Numerica (GDN/CNPq). On the other hand, research in numerical dosimetry leads to a constant improvement on the resolution of voxel phantoms leading thus to a new requirement, namely, to develop new estimates of dose. Therefore, this work also performs an update of the MAX (Male Adult voXel)/EGS4 ECM for the MASH (Adult MaleMeSH)/EGSnrc ECM and presents instances of dosimetric evaluations using the new ECM. Besides the update of the phantom and the MC code, the algorithm of the source used has also been improved in contrast to previous publications. (author)

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.

Evaluation of the UF/NCI hybrid computational phantoms for use in organ dosimetry of pediatric patients undergoing fluoroscopically guided cardiac procedures

Science.gov (United States)

Marshall, Emily L.; Borrego, David; Tran, Trung; Fudge, James C.; Bolch, Wesley E.

2018-03-01

Epidemiologic data demonstrate that pediatric patients face a higher relative risk of radiation induced cancers than their adult counterparts at equivalent exposures. Infants and children with congenital heart defects are a critical patient population exposed to ionizing radiation during life-saving procedures. These patients will likely incur numerous procedures throughout their lifespan, each time increasing their cumulative radiation absorbed dose. As continued improvements in long-term prognosis of congenital heart defect patients is achieved, a better understanding of organ radiation dose following treatment becomes increasingly vital. Dosimetry of these patients can be accomplished using Monte Carlo radiation transport simulations, coupled with modern anatomical patient models. The aim of this study was to evaluate the performance of the University of Florida/National Cancer Institute (UF/NCI) pediatric hybrid computational phantom library for organ dose assessment of patients that have undergone fluoroscopically guided cardiac catheterizations. In this study, two types of simulations were modeled. A dose assessment was performed on 29 patient-specific voxel phantoms (taken as representing the patient’s true anatomy), height/weight-matched hybrid library phantoms, and age-matched reference phantoms. Two exposure studies were conducted for each phantom type. First, a parametric study was constructed by the attending pediatric interventional cardiologist at the University of Florida to model the range of parameters seen clinically. Second, four clinical cardiac procedures were simulated based upon internal logfiles captured by a Toshiba Infinix-i Cardiac Bi-Plane fluoroscopic unit. Performance of the phantom library was quantified by computing both the percent difference in individual organ doses, as well as the organ dose root mean square values for overall phantom assessment between the matched phantoms (UF/NCI library or reference) and the patient

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)

Phantoms and computational models in therapy, diagnosis and protection

International Nuclear Information System (INIS)

Anon.

1992-01-01

The development of realistic body phantoms and computational models is strongly dependent on the availability of comprehensive human anatomical data. This information is often missing, incomplete or not easily available. Therefore, emphasis is given in the Report to organ and body masses and geometries. The influence of age, sex and ethnic origins in human anatomy is considered. Suggestions are given on how suitable anatomical data can be either extracted from published information or obtained from measurements on the local population. Existing types of phantoms and computational models used with photons, electrons, protons and neutrons are reviewed in this Report. Specifications of those considered important to the maintenance and development of reliable radiation dosimetry and measurement are given. The information provided includes a description of the phantom or model, together with diagrams or photographs and physical dimensions. The tissues within body sections are identified and the tissue substitutes used or recommended are listed. The uses of the phantom or model in radiation dosimetry and measurement are outlined. The Report deals predominantly with phantom and computational models representing the human anatomy, with a short Section devoted to animal phantoms in radiobiology

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)

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)

A Novel Simple Phantom for Verifying the Dose of Radiation Therapy

Directory of Open Access Journals (Sweden)

J. H. Lee

2015-01-01

Full Text Available A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with 60Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions.

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.

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.

Voxel anthropomorphic phantoms: review of models used for ionising radiation dosimetry

International Nuclear Information System (INIS)

Lemosquet, A.; Carlan, L. de; Clairand, I.

2003-01-01

Computational anthropomorphic phantoms have been used since the 1970's for dosimetric calculations. Realistic geometries are required for this operation, resulting in the development of ever more accurate phantoms. Voxel phantoms, consisting of a set of small-volume elements, appeared towards the end of the 1980's, and significantly improved on the original mathematical models. Voxel phantoms are models of the human body, obtained using computed tomography (CT) or magnetic resonance images (MRI). These phantoms are an extremely accurate representation of the human anatomy. This article provides a review of the literature available on the development of these phantoms and their applications in ionising radiation dosimetry. The bibliographical study has shown that there is a wide range of phantoms, covering various characteristics of the general population in terms of sex, age or morphology, and that they are used in applications relating to all aspects of ionising radiation. (author)

Hubungan Phantom Vibration Syndrome Terhadap Sleep Disorder dan Kondisi Stress

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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.

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.

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)

Phantom inflation and the 'Big Trip'

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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.

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.

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.

Design of a head phantom produced on a 3D rapid prototyping printer and comparison with a RANDO and 3M lucite head phantom in eye dosimetry applications.

Science.gov (United States)

Homolka, Peter; Figl, Michael; Wartak, Andreas; Glanzer, Mathias; Dünkelmeyer, Martina; Hojreh, Azadeh; Hummel, Johann

2017-04-21

An anthropomorphic head phantom including eye inserts allowing placement of TLDs 3 mm below the cornea has been produced on a 3D printer using a photo-cured acrylic resin to best allow tissue equivalence. Thus H p (3) can be determined in radiological and interventional photon radiation fields. Eye doses and doses to the forehead have been compared to an Alderson RANDO head and a 3M Lucite skull phantom in terms of surface dose per incident air kerma for frontal irradiation since the commercial phantoms do not allow placement of TLDs 3 mm below the corneal surface. A comparison of dose reduction factors (DRFs) of a common lead glasses model has also been performed. Eye dose per incident air kerma were comparable between all three phantoms (printed phantom: 1.40, standard error (SE) 0.04; RANDO: 1.36, SE 0.03; 3M: 1.37, SE 0.03). Doses to the forehead were identical to eye surface doses for the printed phantom and the RANDO head (ratio 1.00 SE 0.04, and 0.99 SE 0.03, respectively). In the 3M Lucite skull phantom dose on the forehead was 15% lower than dose to the eyes attributable to phantom properties. DRF of a sport frame style leaded glasses model with 0.75 mm lead equivalence measured were 6.8 SE 0.5, 9.3 SE 0.4 and 10.5 SE 0.5 for the RANDO head, the printed phantom, and the 3M Lucite head phantom, respectively, for frontal irradiation. A comparison of doses measured in 3 mm depth and on the surface of the eyes in the printed phantom revealed no difference larger than standard errors from TLD dosimetry. 3D printing offers an interesting opportunity for phantom design with increasing potential as printers allowing combinations of tissue substitutes will become available. Variations between phantoms may provide a useful indication of uncertainty budgets when using phantom measurements to estimate individual personnel doses.

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.

OSL Based Anthropomorphic Phantom and Real-Time Organ Dosimetry

Energy Technology Data Exchange (ETDEWEB)

David E. Hintenlang, Ph.D

2009-02-10

The overall objective of this project was the development of a dosimetry system that provides the direct measurement of organ does in real-time with a sensitivity that makes it an effective tool for applications in a wide variety of health physics applications. The system included the development of a real-time readout system for fiber optic coupled (FOC) dosimeters that is integrated with a state-of-art anthropomorphic phantom to provide instantaneous measures of organ doses throughout the phantom. The small size of the FOC detectors and optical fibers allow the sensitive volume of the detector to be located at organ centroids (or multiple locations distributed through the organ) within a tissue equivalent, anthropomorphic phantom without perturbing the tissue equivalent features of the phantom. The developed phantom/dosimetry system can be used in any environment where personnel may be exposed to gamma or x-ray radiations to provide the most accurate determinations of organ and effective doses possible to date.

OSL Based Anthropomorphic Phantom and Real-Time Organ Dosimetry

International Nuclear Information System (INIS)

Hintenlang, David E.

2009-01-01

The overall objective of this project was the development of a dosimetry system that provides the direct measurement of organ doses in real-time with a sensitivity that makes it an effective tool for applications in a wide variety of health physics applications. The system included the development of a real-time readout system for fiber optic coupled (FOC) dosimeters that is integrated with a state-of-art anthropomorphic phantom to provide instantaneous measures of organ doses throughout the phantom. The small size of the FOC detectors and optical fibers allow the sensitive volume of the detector to be located at organ centroids (or multiple locations distributed through the organ) within a tissue equivalent, anthropomorphic phantom without perturbing the tissue equivalent features of the phantom. The developed phantom/dosimetry system can be used in any environment where personnel may be exposed to gamma or x-ray radiations to provide the most accurate determinations of organ and effective doses possible to date

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

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

Performance evaluation of a digital mammography unit using a contrast-detail phantom

Science.gov (United States)

Elizalde-Cabrera, J.; Brandan, M.-E.

2015-01-01

The relation between image quality and mean glandular dose (MGD) has been studied for a Senographe 2000D mammographic unit used for research in our laboratory. The magnitudes were evaluated for a clinically relevant range of acrylic thicknesses and radiological techniques. The CDMAM phantom was used to determine the contrast-detail curve. Also, an alternative method based on the analysis of signal-to-noise (SNR) and contrast-to-noise (CNR) ratios from the CDMAM image was proposed and applied. A simple numerical model was utilized to successfully interpret the results. Optimum radiological techniques were determined using the figures-of-merit FOMSNR=SNR2/MGD and FOMCNR=CNR2/MGD. Main results were: the evaluation of the detector response flattening process (it reduces by about one half the spatial non-homogeneities due to the X- ray field), MGD measurements (the values comply with standards), and verification of the automatic exposure control performance (it is sensitive to fluence attenuation, not to contrast). For 4-5 cm phantom thicknesses, the optimum radiological techniques were Rh/Rh 34 kV to optimize SNR, and Rh/Rh 28 kV to optimize CNR.

Development of skeletal system for mesh-type ICRP reference adult phantoms

Science.gov (United States)

Yeom, Yeon Soo; Wang, Zhao Jun; Tat Nguyen, Thang; Kim, Han Sung; Choi, Chansoo; Han, Min Cheol; Kim, Chan Hyeong; Lee, Jai Ki; Chung, Beom Sun; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik

2016-10-01

The reference adult computational phantoms of the international commission on radiological protection (ICRP) described in Publication 110 are voxel-type computational phantoms based on whole-body computed tomography (CT) images of adult male and female patients. The voxel resolutions of these phantoms are in the order of a few millimeters and smaller tissues such as the eye lens, the skin, and the walls of some organs cannot be properly defined in the phantoms, resulting in limitations in dose coefficient calculations for weakly penetrating radiations. In order to address the limitations of the ICRP-110 phantoms, an ICRP Task Group has been recently formulated and the voxel phantoms are now being converted to a high-quality mesh format. As a part of the conversion project, in the present study, the skeleton models, one of the most important and complex organs of the body, were constructed. The constructed skeleton models were then tested by calculating red bone marrow (RBM) and endosteum dose coefficients (DCs) for broad parallel beams of photons and electrons and comparing the calculated values with those of the original ICRP-110 phantoms. The results show that for the photon exposures, there is a generally good agreement in the DCs between the mesh-type phantoms and the original voxel-type ICRP-110 phantoms; that is, the dose discrepancies were less than 7% in all cases except for the 0.03 MeV cases, for which the maximum difference was 14%. On the other hand, for the electron exposures (⩽4 MeV), the DCs of the mesh-type phantoms deviate from those of the ICRP-110 phantoms by up to ~1600 times at 0.03 MeV, which is indeed due to the improvement of the skeletal anatomy of the developed skeleton mesh models.

Enforcing dust mass conservation in 3D simulations of tightly coupled grains with the PHANTOM SPH code

Science.gov (United States)

Ballabio, G.; Dipierro, G.; Veronesi, B.; Lodato, G.; Hutchison, M.; Laibe, G.; Price, D. J.

2018-06-01

We describe a new implementation of the one-fluid method in the SPH code PHANTOM to simulate the dynamics of dust grains in gas protoplanetary discs. We revise and extend previously developed algorithms by computing the evolution of a new fluid quantity that produces a more accurate and numerically controlled evolution of the dust dynamics. Moreover, by limiting the stopping time of uncoupled grains that violate the assumptions of the terminal velocity approximation, we avoid fatal numerical errors in mass conservation. We test and validate our new algorithm by running 3D SPH simulations of a large range of disc models with tightly and marginally coupled grains.

Porous phantoms for PET and SPECT performance evaluation and quality assurance

International Nuclear Information System (INIS)

DiFilippo, Frank P.; Price, James P.; Kelsch, Daniel N.; Muzic, Raymond F. Jr.

2004-01-01

Characterization of PET and SPECT imaging performance often requires phantoms with complex radionuclide distributions. For example, lesion detection studies use multiple spherical regions of specific target-to-background ratios to simulate cancerous lesions. Such complex distributions are typically created using phantoms with multiple fillable chambers. However, such phantoms are typically difficult and time-consuming to prepare accurately and reproducibly. A new approach using a single-chamber phantom with a porous core can overcome these difficulties. Methods: Prototypes of two designs of porous core phantoms were produced and evaluated. The 'hot spheres' phantom contained a multitude of simulated spherical lesions with diameters ranging from 6.35 to 25.4 mm ('multi-resolution' slice) and with lesion-to-background ratios ranging from 1.6 to 4.4 ('multi-contrast' slice). The 'multi-attenuation' phantom consisted of two halves. One half contained a porous core to produce regions of different attenuation but uniform activity. The other half mimicked the NEMA-94 design with cold inserts of different attenuation. Results: Both phantoms produced the expected radionuclide distributions while requiring the preparation of only a single radionuclide solution and with much reduced preparation time. In images taken on clinical PET and SPECT scanners, the porous core structures were found to contribute negligible background noise or artifact. The measured lesion-to-background ratios from the hot spheres phantom differed slightly from calculated values, with the differences attributed mainly to uncertainty in pore diameter. The measured attenuation coefficients from the multi-attenuation phantom agreed well with expected values. However, it was found that trapped air bubbles due to manufacturing defects in the porous core could potentially cause quantitative errors. Conclusion: The hot spheres and multi-attenuation porous phantoms exhibited a wide range of imaging features

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.

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.

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

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

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)

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...

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.

Whole-body detector calibrating with a modular phantom

Energy Technology Data Exchange (ETDEWEB)

Minev, L; Boshkova, T; Uzunov, P [Sofia Univ. (Bulgaria). Fizicheski Fakultet

1996-12-31

Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as `zero` -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs.

Whole-body detector calibrating with a modular phantom

International Nuclear Information System (INIS)

Minev, L.; Boshkova, T.; Uzunov, P.

1995-01-01

Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as 'zero' -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs

Capturing the Perceived Phantom Limb through Virtual Reality

Directory of Open Access Journals (Sweden)

Christian Rogers

2016-01-01

Full Text Available Phantom limb is the sensation amputees may feel when the missing limb is still attached to the body and is still moving as it would if it still existed. Despite there being between 50 and 80% of amputees who report neuropathic pain, also known as phantom limb pain (PLP, there is still little understanding of why PLP occurs. There are no fully effective long-term treatments available. One of the struggles with PLP is the difficulty for amputees to describe the sensations of their phantom limbs. The sensations may be of a limb that is in a position that is impossible for a normal limb to attain. The goal of this project was to treat those with PLP by developing a system to communicate the sensations those with PLP were experiencing accurately and easily through various hand positions using a model arm with a user friendly interface. The system was developed with Maya 3D animation software, the Leap Motion input device, and the Unity game engine. The 3D modeled arm was designed to mimic the phantom sensation being able to go beyond normal joint extensions of regular arms. The purpose in doing so was to obtain a true 3D visualization of the phantom limb.

Heterogeneous Breast Phantom Development for Microwave Imaging Using Regression Models

Directory of Open Access Journals (Sweden)

Camerin Hahn

2012-01-01

Full Text Available As new algorithms for microwave imaging emerge, it is important to have standard accurate benchmarking tests. Currently, most researchers use homogeneous phantoms for testing new algorithms. These simple structures lack the heterogeneity of the dielectric properties of human tissue and are inadequate for testing these algorithms for medical imaging. To adequately test breast microwave imaging algorithms, the phantom has to resemble different breast tissues physically and in terms of dielectric properties. We propose a systematic approach in designing phantoms that not only have dielectric properties close to breast tissues but also can be easily shaped to realistic physical models. The approach is based on regression model to match phantom's dielectric properties with the breast tissue dielectric properties found in Lazebnik et al. (2007. However, the methodology proposed here can be used to create phantoms for any tissue type as long as ex vivo, in vitro, or in vivo tissue dielectric properties are measured and available. Therefore, using this method, accurate benchmarking phantoms for testing emerging microwave imaging algorithms can be developed.

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.

Solid tissue simulating phantoms having absorption at 970 nm for diffuse optics

Science.gov (United States)

Kennedy, Gordon T.; Lentsch, Griffin R.; Trieu, Brandon; Ponticorvo, Adrien; Saager, Rolf B.; Durkin, Anthony J.

2017-07-01

Tissue simulating phantoms can provide a valuable platform for quantitative evaluation of the performance of diffuse optical devices. While solid phantoms have been developed for applications related to characterizing exogenous fluorescence and intrinsic chromophores such as hemoglobin and melanin, we report the development of a poly(dimethylsiloxane) (PDMS) tissue phantom that mimics the spectral characteristics of tissue water. We have developed these phantoms to mimic different water fractions in tissue, with the purpose of testing new devices within the context of clinical applications such as burn wound triage. Compared to liquid phantoms, cured PDMS phantoms are easier to transport and use and have a longer usable life than gelatin-based phantoms. As silicone is hydrophobic, 9606 dye was used to mimic the optical absorption feature of water in the vicinity of 970 nm. Scattering properties are determined by adding titanium dioxide, which yields a wavelength-dependent scattering coefficient similar to that observed in tissue in the near-infrared. Phantom properties were characterized and validated using the techniques of inverse adding-doubling and spatial frequency domain imaging. Results presented here demonstrate that we can fabricate solid phantoms that can be used to simulate different water fractions.

Usefulness of ACR MRI phantom for quality assurance of MRI instruments

International Nuclear Information System (INIS)

Lee, Jung Whee; Ahn, Kook Jin; Lee, Seung Koo; Na, Dong Gyu; Oh, Chang Hyun; Chang, Yong Min; Lim, Tae Hwan

2006-01-01

To examine whether the ACR phantom could be used in quality standards for magnetic resonance imaging (MRI) instruments in Korea. We conducted the phantom test using the ACR MRI phantom in 20 MRI instruments currently used in Korea. According to ACR criteria, we acquired the phantom images which were then assessed by the following seven tests: geometric accuracy, high spatial resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, and low contrast object detectability. The phantom images were interpreted by three experienced radiologists according to ACR criteria. Then, we examined the failure rate of each test and evaluated the inter-observer variation in the measurements and test failure. The failure rate of each test could be broken into the following components: geometric accuracy (11-21%), high contrast spatial resolution (10-15%), slice thickness accuracy(6-22%), slice position accuracy (5-17%), image intensity uniformity (6%), percent signal ghosting (16%), and low contrast object detectability (8-10%). In this series, all the failure rates were less than 30%. In addition, no inter-observer variation was seen in the measurements and test failure. ACR MRI phantom promises to be established as the standard phantom for MRI instruments in Korea because of its objectivity in assessing the phantom images

Tracked ultrasound calibration studies with a phantom made of LEGO bricks

Science.gov (United States)

Soehl, Marie; Walsh, Ryan; Rankin, Adam; Lasso, Andras; Fichtinger, Gabor

2014-03-01

In this study, spatial calibration of tracked ultrasound was compared by using a calibration phantom made of LEGO® bricks and two 3-D printed N-wire phantoms. METHODS: The accuracy and variance of calibrations were compared under a variety of operating conditions. Twenty trials were performed using an electromagnetic tracking device with a linear probe and three trials were performed using varied probes, varied tracking devices and the three aforementioned phantoms. The accuracy and variance of spatial calibrations found through the standard deviation and error of the 3-D image reprojection were used to compare the calibrations produced from the phantoms. RESULTS: This study found no significant difference between the measured variables of the calibrations. The average standard deviation of multiple 3-D image reprojections with the highest performing printed phantom and those from the phantom made of LEGO® bricks differed by 0.05 mm and the error of the reprojections differed by 0.13 mm. CONCLUSION: Given that the phantom made of LEGO® bricks is significantly less expensive, more readily available, and more easily modified than precision-machined N-wire phantoms, it prompts to be a viable calibration tool especially for quick laboratory research and proof of concept implementations of tracked ultrasound navigation.

Quality assessment of brain images by Hoffman phantom

International Nuclear Information System (INIS)

Karimian, A.R.; Saddad, F.; Mosalla, B.; Moradkhani, S.; Degbankhan, R.; Pouladi, M.

2002-01-01

The purpose of this investigation is using Hoffman brain phantom for quality assessment of brian images in SPECT system. There are the following standards for quality control in nuclear medicine: American Association of Physicists in Medicine, National Electrical Manufacturers Association, International Electromechanical Commission, International Atomic Energy Agency. Each of the above standards has the following important orders: Physical inspection, Acceptance and Reference Testing, Periodic Q C tests (Daily, Weekly, Monthly, Quarterly, Annually). The above tests are simple physics measures. To more meaningful ones based on performance of some tasks related to clinical application it is better to use from organs' phantoms, such as: brain, cardiac, etc. In this research we made a comparison between normal and abnormal states of Hoffman brain phantom. Methods of Hoffman brain phantom was filled with a solution of Tc- 99 m (5 mCi) and water (1300 cc). this results: The investigation of small abnormalities strongly related to the operating conditions and deviation from best tuning state of the system

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.

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

Phantom positioning variation in the Gamma Knife® Perfexion dosimetry

Energy Technology Data Exchange (ETDEWEB)

Costa, Nathalia Almeida; Potiens, Maria da Penha Albuquerque [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saraiva, Crystian [Hospital do Coracao, Sao Paulo, SP (Brazil)

2015-07-01

The use of small volume ionization chamber has become required for the dosimetry of equipment that use small radiation fields. A pinpoint ionization chamber is ideal for the dosimetry of a Gamma Knife® Perfexion (GKP) unit. In this work, this chamber was inserted into the phantom, and measurements were performed with the phantom in different positions, in order to verify if the change in the phantom positioning affects the dosimetry of the GKP. Three different phantom positions were performed. The variation in the result is within the range allowed for the dosimetry of a GKP equipment. (author)

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

Evaluation of the 1Shot Phantom dedicated to the mammography system using FCR

International Nuclear Information System (INIS)

Nagashima, Chieko; Uchiyama, Nachiko; Moriyama, Noriyuki; Nagata, Mio; Kobayashi, Hiroyuki; Sankoda, Katsuhiro; Saotome, Shigeru; Tagi, Masahiro; Kusunoki, Tetsurou

2009-01-01

Currently daily quality control (QC) tests for mammography systems are generally evaluated by using visual analysis phantoms, which of course means subjective measurement. In our study, however, we evaluated a novel digital phantom, the 1Shot Phantom M plus (1Shot Phantom), together with automatic analysis software dedicated for mammography systems using Fuji computed radiography (FCR). The digital phantom enables objective evaluation by providing for actual physical measurement rather than subjective visual assessment. We measured contrast to noise ratio (CNR), image receptor homogeneity, missed tissue at chest wall side, modulation transfer function (MTF), and geometric distortion utilizing the 1Shot Phantom. We then compared the values obtained using the 1Shot Phantom with values obtained from the European guidelines and International Electrotechnical Commission (IEC) standards. In addition, we evaluated the convenience of using the digital phantom. The values utilizing the 1Shot Phantom and those from the European guidelines and IEC standards were consistent, but the QC tests for the European guidelines and IEC standards methods took about six hours while the same QC tests using the 1Shot Phantom took 10 minutes or less including exposure of the phantom image, measurement, and analysis. In conclusion, the digital phantom and dedicated software proved very useful and produced improved analysis for mammography systems using FCR in clinical daily QC testing because of their objectivity and substantial time-saving convenience. (author)

Preliminary Study on Hybrid Computational Phantom for Radiation Dosimetry Based on Subdivision Surface

International Nuclear Information System (INIS)

Jeong, Jong Hwi; Choi, Sang Hyoun; Cho, Sung Koo; Kim, Chan Hyeong

2007-01-01

The anthropomorphic computational phantoms are classified into two groups. One group is the stylized phantoms, or MIRD phantoms, which are based on mathematical representations of the anatomical structures. The shapes and positions of the organs and tissues in these phantoms can be adjusted by changing the coefficients of the equations in use. The other group is the voxel phantoms, which are based on tomographic images of a real person such as CT, MR and serially sectioned color slice images from a cadaver. Obviously, the voxel phantoms represent the anatomical structures of a human body much more realistically than the stylized phantoms. A realistic representation of anatomical structure is very important for an accurate calculation of radiation dose in the human body. Consequently, the ICRP recently has decided to use the voxel phantoms for the forthcoming update of the dose conversion coefficients. However, the voxel phantoms also have some limitations: (1) The topology and dimensions of the organs and tissues in a voxel model are extremely difficult to change, and (2) The thin organs, such as oral mucosa and skin, cannot be realistically modeled unless the voxel resolution is prohibitively high. Recently, a new approach has been implemented by several investigators. The investigators converted their voxel phantoms to hybrid computational phantoms based on NURBS (Non-Uniform Rational B-Splines) surface, which is smooth and deformable. It is claimed that these new phantoms have the flexibility of the stylized phantom along with the realistic representations of the anatomical structures. The topology and dimensions of the anatomical structures can be easily changed as necessary. Thin organs can be modeled without affecting computational speed or memory requirement. The hybrid phantoms can be also used for 4-D Monte Carlo simulations. In this preliminary study, the external shape of a voxel phantom (i.e., skin), HDRK-Man, was converted to a hybrid computational

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

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)

A methodology to develop computational phantoms with adjustable posture for WBC calibration

International Nuclear Information System (INIS)

Fonseca, T C Ferreira; Vanhavere, F; Bogaerts, R; Hunt, John

2014-01-01

A Whole Body Counter (WBC) is a facility to routinely assess the internal contamination of exposed workers, especially in the case of radiation release accidents. The calibration of the counting device is usually done by using anthropomorphic physical phantoms representing the human body. Due to such a challenge of constructing representative physical phantoms a virtual calibration has been introduced. The use of computational phantoms and the Monte Carlo method to simulate radiation transport have been demonstrated to be a worthy alternative. In this study we introduce a methodology developed for the creation of realistic computational voxel phantoms with adjustable posture for WBC calibration. The methodology makes use of different software packages to enable the creation and modification of computational voxel phantoms. This allows voxel phantoms to be developed on demand for the calibration of different WBC configurations. This in turn helps to study the major source of uncertainty associated with the in vivo measurement routine which is the difference between the calibration phantoms and the real persons being counted. The use of realistic computational phantoms also helps the optimization of the counting measurement. Open source codes such as MakeHuman and Blender software packages have been used for the creation and modelling of 3D humanoid characters based on polygonal mesh surfaces. Also, a home-made software was developed whose goal is to convert the binary 3D voxel grid into a MCNPX input file. This paper summarizes the development of a library of phantoms of the human body that uses two basic phantoms called MaMP and FeMP (Male and Female Mesh Phantoms) to create a set of male and female phantoms that vary both in height and in weight. Two sets of MaMP and FeMP phantoms were developed and used for efficiency calibration of two different WBC set-ups: the Doel NPP WBC laboratory and AGM laboratory of SCK-CEN in Mol, Belgium. (paper)

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

A methodology to develop computational phantoms with adjustable posture for WBC calibration

Science.gov (United States)

Ferreira Fonseca, T. C.; Bogaerts, R.; Hunt, John; Vanhavere, F.

2014-11-01

A Whole Body Counter (WBC) is a facility to routinely assess the internal contamination of exposed workers, especially in the case of radiation release accidents. The calibration of the counting device is usually done by using anthropomorphic physical phantoms representing the human body. Due to such a challenge of constructing representative physical phantoms a virtual calibration has been introduced. The use of computational phantoms and the Monte Carlo method to simulate radiation transport have been demonstrated to be a worthy alternative. In this study we introduce a methodology developed for the creation of realistic computational voxel phantoms with adjustable posture for WBC calibration. The methodology makes use of different software packages to enable the creation and modification of computational voxel phantoms. This allows voxel phantoms to be developed on demand for the calibration of different WBC configurations. This in turn helps to study the major source of uncertainty associated with the in vivo measurement routine which is the difference between the calibration phantoms and the real persons being counted. The use of realistic computational phantoms also helps the optimization of the counting measurement. Open source codes such as MakeHuman and Blender software packages have been used for the creation and modelling of 3D humanoid characters based on polygonal mesh surfaces. Also, a home-made software was developed whose goal is to convert the binary 3D voxel grid into a MCNPX input file. This paper summarizes the development of a library of phantoms of the human body that uses two basic phantoms called MaMP and FeMP (Male and Female Mesh Phantoms) to create a set of male and female phantoms that vary both in height and in weight. Two sets of MaMP and FeMP phantoms were developed and used for efficiency calibration of two different WBC set-ups: the Doel NPP WBC laboratory and AGM laboratory of SCK-CEN in Mol, Belgium.

Computational high-resolution heart phantoms for medical imaging and dosimetry simulations

Energy Technology Data Exchange (ETDEWEB)

Gu Songxiang; Kyprianou, Iacovos [Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD (United States); Gupta, Rajiv, E-mail: songxiang.gu@fda.hhs.gov, E-mail: rgupta1@partners.org, E-mail: iacovos.kyprianou@fda.hhs.gov [Massachusetts General Hospital, Boston, MA (United States)

2011-09-21

Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive therapies for CAD such as angioplasty and stenting are rendered under fluoroscopic guidance. Both invasive and non-invasive imaging modalities employ ionizing radiation and there is concern for deterministic and stochastic effects of radiation. Accurate simulation to optimize image quality with minimal radiation dose requires detailed, gender-specific anthropomorphic phantoms with anatomically correct heart and associated vasculature. Such phantoms are currently unavailable. This paper describes an open source heart phantom development platform based on a graphical user interface. Using this platform, we have developed seven high-resolution cardiac/coronary artery phantoms for imaging and dosimetry from seven high-quality CTA datasets. To extract a phantom from a coronary CTA, the relationship between the intensity distribution of the myocardium, the ventricles and the coronary arteries is identified via histogram analysis of the CTA images. By further refining the segmentation using anatomy-specific criteria such as vesselness, connectivity criteria required by the coronary tree and image operations such as active contours, we are able to capture excellent detail within our phantoms. For example, in one of the female heart phantoms, as many as 100 coronary artery branches could be identified. Triangular meshes are fitted to segmented high-resolution CTA data. We have also developed a visualization tool for adding stenotic lesions to the coronaries. The male and female heart phantoms generated so far have been cross-registered and entered in the mesh-based Virtual Family of phantoms with matched age/gender information. Any phantom in this family, along with user

Computational high-resolution heart phantoms for medical imaging and dosimetry simulations

International Nuclear Information System (INIS)

Gu Songxiang; Kyprianou, Iacovos; Gupta, Rajiv

2011-01-01

Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive therapies for CAD such as angioplasty and stenting are rendered under fluoroscopic guidance. Both invasive and non-invasive imaging modalities employ ionizing radiation and there is concern for deterministic and stochastic effects of radiation. Accurate simulation to optimize image quality with minimal radiation dose requires detailed, gender-specific anthropomorphic phantoms with anatomically correct heart and associated vasculature. Such phantoms are currently unavailable. This paper describes an open source heart phantom development platform based on a graphical user interface. Using this platform, we have developed seven high-resolution cardiac/coronary artery phantoms for imaging and dosimetry from seven high-quality CTA datasets. To extract a phantom from a coronary CTA, the relationship between the intensity distribution of the myocardium, the ventricles and the coronary arteries is identified via histogram analysis of the CTA images. By further refining the segmentation using anatomy-specific criteria such as vesselness, connectivity criteria required by the coronary tree and image operations such as active contours, we are able to capture excellent detail within our phantoms. For example, in one of the female heart phantoms, as many as 100 coronary artery branches could be identified. Triangular meshes are fitted to segmented high-resolution CTA data. We have also developed a visualization tool for adding stenotic lesions to the coronaries. The male and female heart phantoms generated so far have been cross-registered and entered in the mesh-based Virtual Family of phantoms with matched age/gender information. Any phantom in this family, along with user

[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.

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

Computational hybrid anthropometric paediatric phantom library for internal radiation dosimetry

Science.gov (United States)

Xie, Tianwu; Kuster, Niels; Zaidi, Habib

2017-04-01

Hybrid computational phantoms combine voxel-based and simplified equation-based modelling approaches to provide unique advantages and more realism for the construction of anthropomorphic models. In this work, a methodology and C++ code are developed to generate hybrid computational phantoms covering statistical distributions of body morphometry in the paediatric population. The paediatric phantoms of the Virtual Population Series (IT’IS Foundation, Switzerland) were modified to match target anthropometric parameters, including body mass, body length, standing height and sitting height/stature ratio, determined from reference databases of the National Centre for Health Statistics and the National Health and Nutrition Examination Survey. The phantoms were selected as representative anchor phantoms for the newborn, 1, 2, 5, 10 and 15 years-old children, and were subsequently remodelled to create 1100 female and male phantoms with 10th, 25th, 50th, 75th and 90th body morphometries. Evaluation was performed qualitatively using 3D visualization and quantitatively by analysing internal organ masses. Overall, the newly generated phantoms appear very reasonable and representative of the main characteristics of the paediatric population at various ages and for different genders, body sizes and sitting stature ratios. The mass of internal organs increases with height and body mass. The comparison of organ masses of the heart, kidney, liver, lung and spleen with published autopsy and ICRP reference data for children demonstrated that they follow the same trend when correlated with age. The constructed hybrid computational phantom library opens up the prospect of comprehensive radiation dosimetry calculations and risk assessment for the paediatric population of different age groups and diverse anthropometric parameters.

Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes.

Directory of Open Access Journals (Sweden)

Yu-Hsuan Lin

Full Text Available BACKGROUND: Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. METHODS: A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. RESULTS: The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. CONCLUSION: This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships.

Development of polygonal surface version of ICRP reference phantoms: Preliminary study for posture change

International Nuclear Information System (INIS)

Nguyen, Tat Thang; Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong

2013-01-01

Even though International Commission on Radiological Protection (ICRP) officially adopted a set of adult male and female voxel phantoms as the ICRP reference phantoms, there are several critical limitations due to the nature of voxel geometry and their low voxel resolutions. In order to overcome these limitations of the ICRP phantoms, we are currently developing polygonal surface version of ICRP reference phantoms by directly converting the ICRP voxel phantoms to polygonal surface geometries. Among the many advantages of the ICRP polygonal surface phantom, especially, it is flexible and deformable. In principle, it is, therefore, possible to make the posture-changed ICRP phantoms which can provide more accurate dose values for exposure situations strongly relevant to worker's postures. As a preliminary study for developing the posture-changed ICRP phantoms, in this work we changed the posture of the preliminary version of ICRP male polygon-surface phantom constructed in the previous study. Organ doses were then compared between original and posture-changed phantoms. In the present study, we successfully changed a posture of the preliminary version of ICRP male polygon-surface phantom to the walking posture. From this results, it was explicitly shown that the polygon-surface version of the ICRP phantoms can be sufficiently modified to be various postures with the posture-changing method used in this study. In addition, it was demonstrated that phantom's posture must be considered in certain exposure situations, which can differ dose values from the conventional standing-posture phantom

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.

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.

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.

AdS Black Hole with Phantom Scalar Field

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Limei Zhang

2017-01-01

Full Text Available We present an AdS black hole solution with Ricci flat horizon in Einstein-phantom scalar theory. The phantom scalar fields just depend on the transverse coordinates x and y, which are parameterized by the parameter α. We study the thermodynamics of the AdS phantom black hole. Although its horizon is a Ricci flat Euclidean space, we find that the thermodynamical properties of the black hole solution are qualitatively the same as those of AdS Schwarzschild black hole. Namely, there exists a minimal temperature and the large black hole is thermodynamically stable, while the smaller one is unstable, so there is a so-called Hawking-Page phase transition between the large black hole and the thermal gas solution in the AdS space-time in Poincare coordinates. We also calculate the entanglement entropy for a strip geometry dual to the AdS phantom black holes and find that the behavior of the entanglement entropy is qualitatively the same as that of the black hole thermodynamical entropy.

Computer phantoms for simulating ultrasound B-mode and CFM images

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt; Munk, Peter

1997-01-01

in a file that defines their position and amplitude. Adjusting the number of scatterers and their relative amplitude yields the proper image.Five different computer phantoms are described. The first one consists of a number of point targets. It is used for studying the point spread function as a function...... of spatial position, and can give an indication of sidelobe levels and focusing abilities. The second phantom contains a number of cysts and point tagets along with a homogeneous speckle pattern. This is used for investigating image contrast, and the system's ability to detect low-contrast objects. The third...... phantom is for realistic clinical imaging. It contains the image of a 12 week old fetus, where the placenta and the upper body of the fetus is visible. This phantom gives an indication of the whole system's capability for real imaging. The current fetus phantom is only two-dimensional, as it is constant...

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

Design and fabrication of a realistic anthropomorphic heterogeneous head phantom for MR purposes.

Directory of Open Access Journals (Sweden)

Sossena Wood

Full Text Available The purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications.An eight compartment, physical anthropomorphic head phantom was developed from a 3T MRI dataset of a healthy male. The designed phantom was successfully built and preliminarily evaluated through an application that involves electromagnetic-tissue interactions: MRI (due to it being an available resource. The developed phantom was filled with media possessing electromagnetic constitutive parameters that correspond to biological tissues at ~297 MHz. A preliminary comparison between an in-vivo human volunteer (based on whom the anthropomorphic head phantom was created and various phantoms types, one being the anthropomorphic heterogeneous head phantom, were performed using a 7 Tesla human MRI scanner.Echo planar imaging was performed and minimal ghosting and fluctuations were observed using the proposed anthropomorphic phantom. The magnetic field distributions (during MRI experiments at 7 Tesla and the scattering parameter (measured using a network analyzer were most comparable between the anthropomorphic heterogeneous head phantom and an in-vivo human volunteer.The developed anthropomorphic heterogeneous head phantom can be used as a resource to various researchers in applications that involve electromagnetic-biological tissue interactions such as MRI.

Quadrature Slotted Surface Coil Pair for Magnetic Resonance Imaging at 4 Tesla: Phantom Study

Directory of Open Access Journals (Sweden)

Solis S.E.

2012-01-01

Full Text Available A coil array was composed of two slotted surface coils forming a structure with two plates at 900, each one having 6 circular slots and is introduced in this paper. Numerical simulations of the magnetic field of this coil array were performed at 170 MHz using the finite element method to study its behaviour. This coil array was developed for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode and quadrature driven. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. In vitro images showed the feasibility of this coil array for standard pulses and high field magnetic resonance imaging.

Whole-body voxel phantoms of paediatric patients—UF Series B

Science.gov (United States)

Lee, Choonik; Lee, Choonsik; Williams, Jonathan L.; Bolch, Wesley E.

2006-09-01

Following the previous development of the head and torso voxel phantoms of paediatric patients for use in medical radiation protection (UF Series A), a set of whole-body voxel phantoms of paediatric patients (9-month male, 4-year female, 8-year female, 11-year male and 14-year male) has been developed through the attachment of arms and legs from segmented CT images of a healthy Korean adult (UF Series B). Even though partial-body phantoms (head-torso) may be used in a variety of medical dose reconstruction studies where the extremities are out-of-field or receive only very low levels of scatter radiation, whole-body phantoms play important roles in general radiation protection and in nuclear medicine dosimetry. Inclusion of the arms and legs is critical for dosimetry studies of paediatric patients due to the presence of active bone marrow within the extremities of children. While the UF Series A phantoms preserved the body dimensions and organ masses as seen in the original patients who were scanned, comprehensive adjustments were made for the Series B phantoms to better match International Commission on Radiological Protection (ICRP) age-interpolated reference body masses, body heights, sitting heights and internal organ masses. The CT images of arms and legs of a Korean adult were digitally rescaled and attached to each phantom of the UF series. After completion, the resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year and 14-year were set at 0.86 mm × 0.86 mm × 3.0 mm, 0.90 mm × 0.90 mm × 5.0 mm, 1.16 mm × 1.16 mm × 6.0 mm, 0.94 mm × 0.94 mm × 6.00 mm and 1.18 mm × 1.18 mm × 6.72 mm, respectively.

Dosimetric characteristics of water equivalent for two solid water phantoms

International Nuclear Information System (INIS)

Wang Jianhua; Wang Xun; Ren Jiangping

2011-01-01

Objective: To investigate the water equivalent of two solid water phantoms. Methods: The X-ray and electron beam depth-ion curves were measured in water and two solid water phantoms, RW3 and Virtual Water. The water-equivalency correction factors for the two solid water phantoms were compared. We measured and calculated the range sealing factors and the fluence correction factors for the two solid water phantoms in the case of electron beams. Results: The average difference between the measured ionization in solid water phantoms and water was 0.42% and 0.16% on 6 MV X-ray (t=-6.15, P=0.001 and t=-1.65, P=0.419) and 0.21% and 0.31% on 10 MV X-ray (t=1.728, P=0.135 and t=-2.296, P=0.061), with 17.4% and 14.5% on 6 MeV electron beams (t=-1.37, P=0.208 and t=-1.47, P=0.179) and 7.0% and 6.0% on 15 MeV electron beams (t=-0.58, P=0.581 and t=-0.90, P=0.395). The water-equivalency correction factors for the two solid water phantoms varied slightly largely, F=58.54, P=0.000 on 6 MV X-ray, F=0.211, P=0.662 on 10 MV X-ray, F=0.97, P=0.353 on 6 MeV electron beams, F=0.14, P=0.717 on 15 MeV electron beams. However, they were almost equal to 1 near the reference depths. The two solid water phantoms showed a similar tread of C pl increasing (F=26.40, P=0.014) and h pl decreasing (F=7.45, P=0.072) with increasing energy. Conclusion: The solid water phantom should undergo a quality control test before being clinical use. (authors)

Early and effective use of ketamine for treatment of phantom limb pain

Directory of Open Access Journals (Sweden)

Harsha Shanthanna

2010-01-01

Full Text Available Treatment for phantom limb pain is difficult and challenging. There is often suboptimum treatment with fewer than 10% receiving lasting relief. Treatments based broadly on other neuropathic pains may not be appropriate for a clinical success. We report a case of phantom limb pain, which proved resistant to multiple analgesics, including opioids and continuous epidural blockade. Treatment with intravenous (IV ketamine as an alternate day infusion, gave complete remission of phantom limb pain. This demonstrates an early and effective use of a potent NMDA antagonist for treatment of phantom limb pain. Mechanisms underlying phantom limb pain are briefly discussed.

Neutron measurements with a tissue-equivalent phantom

Energy Technology Data Exchange (ETDEWEB)

Smith, J W [Health Physics Division, Atomic Energy Establishment, Harwell (United Kingdom)

1962-03-15

This Appendix 3E of the dosimetry experiment at the R-B reactor describes the apparatus used and presents the obtained results. The phantom used was a 1/4-inch thick polythene container, 60 cm high, of elliptical cross-section, with a major axis of 36 cm and a minor axis of 20 cm. This was filled with an approximately tissue-equivalent liquid. A light but rigid internal framework of Perspex supported a series of small detectors through the phantom. The detectors used in the first high-level run at Vinca, to measure flux above 0.5 MeV, were 0.5-cm wide track plates wrapped in cadmium foil. Each track plate was a sandwich of two Ilford El 50 - mu emulsions, with glass backing, separated by a 250-mu polythene radiator, and was oriented at an angle of 45 deg to the front surface of the phantom. Under these conditions the response is constant with neutron energy between 0.5 MeV and 8 MeV at 1.26 X 10 sup - sup 3 tracks/neutron to within +- 15%. The detectors used in the second high-level run were gold foils (260 mg/cm sup 2 thick) for determination of the show neutron distribution. Previous experiments with 0.13 MeV, 2.5 MeV, 14 MeV and Po-Be neutrons have shown that the shape of the curve through a phantom obtained from these gold foils is the same as that given by either manganese foils or sodium samples despite the difference in resonance integrals. From the relaxation length of the neutron flux in the phantom, as measured by the track plates, the mean energy of the neutrons with energies greater than 0.5 MeV may be found by comparison with the relaxation lengths obtained by irradiation of the phantom with monoenergetic neutrons. The results of these experiments are given. Track plate results from the Vinca experiment are shown. It can be seen that the backscattered fast flux is about one-third of the incident fast flux and that the energy indicated by the shape of the curve is considerably lower than the energy of the direct neutrons. It seems possible that the high

Neutron measurements with a tissue-equivalent phantom

Energy Technology Data Exchange (ETDEWEB)

Smith, J W [Health Physics Division, Atomic Energy Establishment, Harwell (United Kingdom)

1962-03-01

This Appendix 3E of the dosimetry experiment at the R-B reactor describes the apparatus used and presents the obtained results. The phantom used was a 1/4-inch thick polythene container, 60 cm high, of elliptical cross-section, with a major axis of 36 cm and a minor axis of 20 cm. This was filled with an approximately tissue-equivalent liquid. A light but rigid internal framework of Perspex supported a series of small detectors through the phantom. The detectors used in the first high-level run at Vinca, to measure flux above 0.5 MeV, were 0.5-cm wide track plates wrapped in cadmium foil. Each track plate was a sandwich of two Ilford El 50 - {mu} emulsions, with glass backing, separated by a 250-{mu} polythene radiator, and was oriented at an angle of 45 deg to the front surface of the phantom. Under these conditions the response is constant with neutron energy between 0.5 MeV and 8 MeV at 1.26 X 10{sup -3} tracks/neutron to within {+-} 15%. The detectors used in the second high-level run were gold foils (260 mg/cm{sup 2} thick) for determination of the show neutron distribution. Previous experiments with 0.13 MeV, 2.5 MeV, 14 MeV and Po-Be neutrons have shown that the shape of the curve through a phantom obtained from these gold foils is the same as that given by either manganese foils or sodium samples despite the difference in resonance integrals. From the relaxation length of the neutron flux in the phantom, as measured by the track plates, the mean energy of the neutrons with energies greater than 0.5 MeV may be found by comparison with the relaxation lengths obtained by irradiation of the phantom with monoenergetic neutrons. The results of these experiments are given. Track plate results from the Vinca experiment are shown. It can be seen that the backscattered fast flux is about one-third of the incident fast flux and that the energy indicated by the shape of the curve is considerably lower than the energy of the direct neutrons. It seems possible that the

Energy-Efficient Resource Allocation for Phantom Cellular Networks with Imperfect CSI

KAUST Repository

Abdelhady, Amr Mohamed Abdelaziz

2017-03-28

Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Meanwhile, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for a two-tier phantom cellular network, The optimization framework includes both EE and SE. We consider densely deployed phantom cellular networks and model the EE optimization problem taking into consideration the inevitable interference in this setup and imperfect channel estimation impairments. To this end, we propose three resource allocation strategies aiming at optimizing this network EE performance metric. Furthermore, we investigate the effect of changing some system parameters on the performance of these strategies, such as phantom cells resource units share, number of deployed phantom cells within a macro cell , number of pilots, and the phantom cells transmission power budget. It is found that increasing the number of pilots will deteriorate the EE performance of the whole setup, while increasing phantom cells transmission power budget will not affect the EE of the whole setup significantly. In addition, we observed that it is always useful to allocate most of the network resource units to the phantom cells tier.

Energy-Efficient Resource Allocation for Phantom Cellular Networks with Imperfect CSI

KAUST Repository

Abdelhady, Amr Mohamed Abdelaziz; Amin, Osama; Alouini, Mohamed-Slim

2017-01-01

Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Meanwhile, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for a two-tier phantom cellular network, The optimization framework includes both EE and SE. We consider densely deployed phantom cellular networks and model the EE optimization problem taking into consideration the inevitable interference in this setup and imperfect channel estimation impairments. To this end, we propose three resource allocation strategies aiming at optimizing this network EE performance metric. Furthermore, we investigate the effect of changing some system parameters on the performance of these strategies, such as phantom cells resource units share, number of deployed phantom cells within a macro cell , number of pilots, and the phantom cells transmission power budget. It is found that increasing the number of pilots will deteriorate the EE performance of the whole setup, while increasing phantom cells transmission power budget will not affect the EE of the whole setup significantly. In addition, we observed that it is always useful to allocate most of the network resource units to the phantom cells tier.

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

Reversible induction of phantom auditory sensations through simulated unilateral hearing loss.

Directory of Open Access Journals (Sweden)

Roland Schaette

Full Text Available Tinnitus, a phantom auditory sensation, is associated with hearing loss in most cases, but it is unclear if hearing loss causes tinnitus. Phantom auditory sensations can be induced in normal hearing listeners when they experience severe auditory deprivation such as confinement in an anechoic chamber, which can be regarded as somewhat analogous to a profound bilateral hearing loss. As this condition is relatively uncommon among tinnitus patients, induction of phantom sounds by a lesser degree of auditory deprivation could advance our understanding of the mechanisms of tinnitus. In this study, we therefore investigated the reporting of phantom sounds after continuous use of an earplug. 18 healthy volunteers with normal hearing wore a silicone earplug continuously in one ear for 7 days. The attenuation provided by the earplugs simulated a mild high-frequency hearing loss, mean attenuation increased from 30 dB at 3 and 4 kHz. 14 out of 18 participants reported phantom sounds during earplug use. 11 participants presented with stable phantom sounds on day 7 and underwent tinnitus spectrum characterization with the earplug still in place. The spectra showed that the phantom sounds were perceived predominantly as high-pitched, corresponding to the frequency range most affected by the earplug. In all cases, the auditory phantom disappeared when the earplug was removed, indicating a causal relation between auditory deprivation and phantom sounds. This relation matches the predictions of our computational model of tinnitus development, which proposes a possible mechanism by which a stabilization of neuronal activity through homeostatic plasticity in the central auditory system could lead to the development of a neuronal correlate of tinnitus when auditory nerve activity is reduced due to the earplug.

Dosimetric study on head CT scans using adult and newborn phantoms

International Nuclear Information System (INIS)

Paiva de O, G. A.; Prata M, A.

2016-10-01

Computed tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns compared to adult patients in head computed tomography scans. Two head phantoms in a cylindrical shape made in PMMA were used, one to adult and another to newborn patient dimensions. The pediatric routine scan protocol from a radiological service was used for the computed tomography scans. They were performed in General Electric Computed Tomography scanner, Bright Speed model with 4 channels. The absorbed dose measurements were performed with a pencil chamber placed into both phantoms. The newborn head phantom was developed in order to compare the amount of absorbed dose by the phantoms when it is used the same acquisition protocol. The dose found for newborn phantom was 29.9% higher than the adult phantom. (Author)

Dosimetric study on head CT scans using adult and newborn phantoms

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Paiva de O, G. A.; Prata M, A., E-mail: giovanni_paiva@hotmail.com [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

Computed tomography is the radiodiagnostic method that most contributes to the dose deposition in population. Therefore, the dose reductions used in these tests are very important, especially for pediatric patients who have a life expectancy greater than the rest of the population. This study purpose to compare the doses generated from newborns compared to adult patients in head computed tomography scans. Two head phantoms in a cylindrical shape made in PMMA were used, one to adult and another to newborn patient dimensions. The pediatric routine scan protocol from a radiological service was used for the computed tomography scans. They were performed in General Electric Computed Tomography scanner, Bright Speed model with 4 channels. The absorbed dose measurements were performed with a pencil chamber placed into both phantoms. The newborn head phantom was developed in order to compare the amount of absorbed dose by the phantoms when it is used the same acquisition protocol. The dose found for newborn phantom was 29.9% higher than the adult phantom. (Author)

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.

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

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

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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)

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)

Hybrid computational phantoms of the male and female newborn patient: NURBS-based whole-body models

International Nuclear Information System (INIS)

Lee, Choonsik; Lodwick, Daniel; Hasenauer, Deanna; Williams, Jonathan L; Lee, Choonik; Bolch, Wesley E

2007-01-01

Anthropomorphic computational phantoms are computer models of the human body for use in the evaluation of dose distributions resulting from either internal or external radiation sources. Currently, two classes of computational phantoms have been developed and widely utilized for organ dose assessment: (1) stylized phantoms and (2) voxel phantoms which describe the human anatomy via mathematical surface equations or 3D voxel matrices, respectively. Although stylized phantoms based on mathematical equations can be very flexible in regard to making changes in organ position and geometrical shape, they are limited in their ability to fully capture the anatomic complexities of human internal anatomy. In turn, voxel phantoms have been developed through image-based segmentation and correspondingly provide much better anatomical realism in comparison to simpler stylized phantoms. However, they themselves are limited in defining organs presented in low contrast within either magnetic resonance or computed tomography images-the two major sources in voxel phantom construction. By definition, voxel phantoms are typically constructed via segmentation of transaxial images, and thus while fine anatomic features are seen in this viewing plane, slice-to-slice discontinuities become apparent in viewing the anatomy of voxel phantoms in the sagittal or coronal planes. This study introduces the concept of a hybrid computational newborn phantom that takes full advantage of the best features of both its stylized and voxel counterparts: flexibility in phantom alterations and anatomic realism. Non-uniform rational B-spline (NURBS) surfaces, a mathematical modeling tool traditionally applied to graphical animation studies, was adopted to replace the limited mathematical surface equations of stylized phantoms. A previously developed whole-body voxel phantom of the newborn female was utilized as a realistic anatomical framework for hybrid phantom construction. The construction of a hybrid

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

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.)

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

Science.gov (United States)

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

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

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

The purpose of this paper is to develop a technique for the construction of a two-compartment anthropomorphic breast phantom specific to an individual patient's pendant breast anatomy. Three-dimensional breast images were acquired on a prototype dedicated breast computed tomography (bCT) scanner as part of an ongoing IRB-approved clinical trial of bCT. The images from the breast of a patient were segmented into adipose and glandular tissue regions and divided into 1.59 mm thick breast sections to correspond to the thickness of polyethylene stock. A computer-controlled water-jet cutting machine was used to cut the outer breast edge and the internal regions corresponding to glandular tissue from the polyethylene. The stack of polyethylene breast segments was encased in a thermoplastic ‘skin’ and filled with water. Water-filled spaces modeled glandular tissue structures and the surrounding polyethylene modeled the adipose tissue compartment. Utility of the phantom was demonstrated by inserting 200 µm microcalcifications as well as by measuring point dose deposition during bCT scanning. Affine registration of the original patient images with bCT images of the phantom showed similar tissue distribution. Linear profiles through the registered images demonstrated a mean coefficient of determination (r 2 ) between grayscale profiles of 0.881. The exponent of the power law describing the anatomical noise power spectrum was identical in the coronal images of the patient's breast and the phantom. Microcalcifications were visualized in the phantom at bCT scanning. The real-time air kerma rate was measured during bCT scanning and fluctuated with breast anatomy. On average, point dose deposition was 7.1% greater than the mean glandular dose. A technique to generate a two-compartment anthropomorphic breast phantom from bCT images has been demonstrated. The phantom is the first, to our knowledge, to accurately model the uncompressed pendant breast and the glandular tissue

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

Design of a phantom multitrous for a gamma camera quality control

International Nuclear Information System (INIS)

Ben Krir, Wafa; Ben Ameur, Narjes

2009-01-01

In this study we presented the technique of scintigraphy in its various theoretical and practical aspects. We have also shown the importance the quality control procedure according to international standards, as NEMA. Starting from different phantoms currently used, developed according to standards, we designed our phantom. On the other part, this implementation has helped to highlight our expectations in Concerning the functionality of the phantom. Indeed, these results were very conclusive since they made it possible to make a very fast cost and quality control without ambiguity lower. We have thus proved the very advanced stage of reliability of our phantom.

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

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

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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.

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

SU-E-P-59: A Graphical Interface for XCAT Phantom Configuration, Generation and Processing

International Nuclear Information System (INIS)

Myronakis, M; Cai, W; Dhou, S; Cifter, F; Lewis, J; Hurwitz, M

2015-01-01

Purpose: To design a comprehensive open-source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac-Torso (XCAT) phantom. Methods: The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing, our MATLAB-based GUI uses slider controls, drop-down lists, buttons and graphical text input to parameterize and process the phantom. Results: Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool-tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software. Conclusion: The GUI simplifies and automates the use of the XCAT phantom for imaging-based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself. We would like to acknowledge funding from MRA, Varian Medical Systems Inc

SU-E-P-59: A Graphical Interface for XCAT Phantom Configuration, Generation and Processing

Energy Technology Data Exchange (ETDEWEB)

Myronakis, M; Cai, W; Dhou, S; Cifter, F; Lewis, J [Brigham and Women’s Hospital, Boston, MA (United States); Hurwitz, M [Newton, MA (United States)

2015-06-15

Purpose: To design a comprehensive open-source, publicly available, graphical user interface (GUI) to facilitate the configuration, generation, processing and use of the 4D Extended Cardiac-Torso (XCAT) phantom. Methods: The XCAT phantom includes over 9000 anatomical objects as well as respiratory, cardiac and tumor motion. It is widely used for research studies in medical imaging and radiotherapy. The phantom generation process involves the configuration of a text script to parameterize the geometry, motion, and composition of the whole body and objects within it, and to generate simulated PET or CT images. To avoid the need for manual editing or script writing, our MATLAB-based GUI uses slider controls, drop-down lists, buttons and graphical text input to parameterize and process the phantom. Results: Our GUI can be used to: a) generate parameter files; b) generate the voxelized phantom; c) combine the phantom with a lesion; d) display the phantom; e) produce average and maximum intensity images from the phantom output files; f) incorporate irregular patient breathing patterns; and f) generate DICOM files containing phantom images. The GUI provides local help information using tool-tip strings on the currently selected phantom, minimizing the need for external documentation. The DICOM generation feature is intended to simplify the process of importing the phantom images into radiotherapy treatment planning systems or other clinical software. Conclusion: The GUI simplifies and automates the use of the XCAT phantom for imaging-based research projects in medical imaging or radiotherapy. This has the potential to accelerate research conducted with the XCAT phantom, or to ease the learning curve for new users. This tool does not include the XCAT phantom software itself. We would like to acknowledge funding from MRA, Varian Medical Systems Inc.

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.

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)

Gravitational Quasinormal Modes of Regular Phantom Black Hole

Directory of Open Access Journals (Sweden)

Jin Li

2017-01-01

Full Text Available We investigate the gravitational quasinormal modes (QNMs for a type of regular black hole (BH known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS, and anti-de Sitter (AdS. In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS, and AdS spacetimes the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameter b, which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced by b. The obtained results might shed some light on the quantum interpretation of QNM perturbation.

A suitability study of the fission product phantom and the bottle manikin absorption phantom for calibration of in vivo bioassay equipment for the DOELAP accreditation testing program

International Nuclear Information System (INIS)

Olsen, P.C.; Lynch, T.P.

1991-08-01

Pacific Northwest laboratory (PNL) conducted an intercomparison study of the Fission Product phantom and the bottle manikin absorption (BOMAB) phantom for the US Department of Energy (DOE) to determine the consistency of calibration response of the two phantoms and their suitability for certification and use under a planned bioassay laboratory accreditation program. The study was initiated to determine calibration factors for both types of phantoms and to evaluate the suitability of their use in DOE Laboratory Accreditation Program (DOELAP) round-robin testing. The BOMAB was found to be more appropriate for the DOELAP testing program. 9 refs., 9 figs., 9 tabs

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)

Fabrication and characterization of silica aerogel as synthetic tissues for medical imaging phantoms

Science.gov (United States)

In, Eunji; Naguib, Hani

2015-05-01

Medical imaging plays an important role in the field of healthcare industry both in clinical settings and in research and development. It is used in prevention, early detection of disease, in choosing the optimal treatment, during surgical interventions and monitoring of the treatment effects. Despite much advancement in the last few decades, rapid change on its technology development and variety of imaging parameters that differ with the manufacturer restrict its further development. Imaging phantom is a calibrating medium that is scanned or imaged in the field of medical imaging to evaluate, analyze and tune the performance of various imaging devices. A phantom used to evaluate an imaging device should respond in a similar manner to how human tissue and organs would act in that specific imaging modality. There has been many research on the phantom materials; however, there has been no attempt to study on the material that mimics the structure of lung or fibrous tissue. So with the need for development of gel with such structure, we tried to mimic this structure with aerogel. Silica aerogels have unique properties that include low density (0.003g/cm) and mesoporosity (pore size 2-50nm), with a high thermal insulation value (0.005W/mK) and high surface area (500-1200m-2/g).] In this study, we cross-linked with di-isocyanate, which is a group in polyurethane to covalently bond the polymer to the surface of silica aerogel to enhance the mechanical properties. By formation of covalent bonds, the structure can be reinforced by widening the interparticle necks while minimally reducing porosity.

Cosmological perturbations in transient phantom inflation scenarios

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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.)

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.

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.

Development of PIMAL: Mathematical Phantom with Moving Arms and Legs

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Akkurt, Hatice [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eckerman, Keith F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2007-05-01

The computational model of the human anatomy (phantom) has gone through many revisions since its initial development in the 1970s. The computational phantom model currently used by the Nuclear Regulatory Commission (NRC) is based on a model published in 1974. Hence, the phantom model used by the NRC staff was missing some organs (e.g., neck, esophagus) and tissues. Further, locations of some organs were inappropriate (e.g., thyroid).Moreover, all the computational phantoms were assumed to be in the vertical-upright position. However, many occupational radiation exposures occur with the worker in other positions. In the first phase of this work, updates on the computational phantom models were reviewed and a revised phantom model, which includes the updates for the relevant organs and compositions, was identified. This revised model was adopted as the starting point for this development work, and hence a series of radiation transport computations, using the Monte Carlo code MCNP5, was performed. The computational results were compared against values reported by the International Commission on Radiation Protection (ICRP) in Publication 74. For some of the organs (e.g., thyroid), there were discrepancies between the computed values and the results reported in ICRP-74. The reasons behind these discrepancies have been investigated and are discussed in this report.Additionally, sensitivity computations were performed to determine the sensitivity of the organ doses for certain parameters, including composition and cross sections used in the simulations. To assess the dose for more realistic exposure configurations, the phantom model was revised to enable flexible positioning of the arms and legs. Furthermore, to reduce the user time for analyses, a graphical user interface (GUI) was developed. The GUI can be used to visualize the positioning of the arms and legs as desired posture is achieved to generate the input file, invoke the computations, and extract the organ dose

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

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)

A resistive mesh phantom for assessing the performance of EIT systems.

Science.gov (United States)

Gagnon, Hervé; Cousineau, Martin; Adler, Andy; Hartinger, Alzbeta E

2010-09-01

Assessing the performance of electrical impedance tomography (EIT) systems usually requires a phantom for validation, calibration, or comparison purposes. This paper describes a resistive mesh phantom to assess the performance of EIT systems while taking into account cabling stray effects similar to in vivo conditions. This phantom is built with 340 precision resistors on a printed circuit board representing a 2-D circular homogeneous medium. It also integrates equivalent electrical models of the Ag/AgCl electrode impedances. The parameters of the electrode models were fitted from impedance curves measured with an impedance analyzer. The technique used to build the phantom is general and applicable to phantoms of arbitrary shape and conductivity distribution. We describe three performance indicators that can be measured with our phantom for every measurement of an EIT data frame: SNR, accuracy, and modeling accuracy. These performance indicators were evaluated on our EIT system under different frame rates and applied current intensities. The performance indicators are dependent on frame rate, operating frequency, applied current intensity, measurement strategy, and intermodulation distortion when performing simultaneous measurements at several frequencies. These parameter values should, therefore, always be specified when reporting performance indicators to better appreciate their significance.

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 ...

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.

Standardization of calibration method of whole-body counter. 1. Calibration by using anthropometric phantoms

International Nuclear Information System (INIS)

Ishikawa, Tetsuo; Matsumoto, Masaki; Uchiyama, Masafumi; Kobayashi, Sadayoshi; Mizushita, Seiichi.

1995-01-01

To standardize the calibration methods of whole-body counters, three anthropometric phantoms were manufactured based on dozens of Japanese average value of body size data. Using these phantoms, the calibrations of some whole-body counters were carried out and the comparison of counting efficiency between anthropometric phantoms and block phantoms, which used to be used for the calibration of whole-body counters generally, was implemented. Five whole-body counters, one scanning system, two stationary systems and two chair systems, were used for this study. The following results were derived: As an example, in NIRS scanning system, the counting efficiency of anthropometric phantom of 162cm height was 12.7% greater than that of block phantom of the same height. This means 137 Cs body burdens in adult men used to be estimated with the excess of about 10%. Body burdens tended to be estimated excessively in adult because the difference of counting efficiency between anthropometric phantom and block phantom increases with increase of height. To standardize body burden data measured with various whole-body counters, the calibration of each whole-body counter should be conducted using anthropometric phantoms and phantoms which used to be used for the calibration of that whole-body counter. (author)

A biomimetic tumor tissue phantom for validating diffusion-weighted MRI measurements.

Science.gov (United States)

McHugh, Damien J; Zhou, Feng-Lei; Wimpenny, Ian; Poologasundarampillai, Gowsihan; Naish, Josephine H; Hubbard Cristinacce, Penny L; Parker, Geoffrey J M

2018-07-01

To develop a biomimetic tumor tissue phantom which more closely reflects water diffusion in biological tissue than previously used phantoms, and to evaluate the stability of the phantom and its potential as a tool for validating diffusion-weighted (DW) MRI measurements. Coaxial-electrospraying was used to generate micron-sized hollow polymer spheres, which mimic cells. The bulk structure was immersed in water, providing a DW-MRI phantom whose apparent diffusion coefficient (ADC) and microstructural properties were evaluated over a period of 10 months. Independent characterization of the phantom's microstructure was performed using scanning electron microscopy (SEM). The repeatability of the construction process was investigated by generating a second phantom, which underwent high resolution synchrotron-CT as well as SEM and MR scans. ADC values were stable (coefficients of variation (CoVs) < 5%), and varied with diffusion time, with average values of 1.44 ± 0.03 µm 2 /ms (Δ = 12 ms) and 1.20 ± 0.05 µm 2 /ms (Δ = 45 ms). Microstructural parameters showed greater variability (CoVs up to 13%), with evidence of bias in sphere size estimates. Similar trends were observed in the second phantom. A novel biomimetic phantom has been developed and shown to be stable over 10 months. It is envisaged that such phantoms will be used for further investigation of microstructural models relevant to characterizing tumor tissue, and may also find application in evaluating acquisition protocols and comparing DW-MRI-derived biomarkers obtained from different scanners at different sites. Magn Reson Med 80:147-158, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is

Pulse-wave propagation in straight-geometry vessels for stiffness estimation: theory, simulations, phantoms and in vitro findings.

Science.gov (United States)

Shahmirzadi, Danial; Li, Ronny X; Konofagou, Elisa E

2012-11-01

Pulse wave imaging (PWI) is an ultrasound-based method for noninvasive characterization of arterial stiffness based on pulse wave propagation. Reliable numerical models of pulse wave propagation in normal and pathological aortas could serve as powerful tools for local pulse wave analysis and a guideline for PWI measurements in vivo. The objectives of this paper are to (1) apply a fluid-structure interaction (FSI) simulation of a straight-geometry aorta to confirm the Moens-Korteweg relationship between the pulse wave velocity (PWV) and the wall modulus, and (2) validate the simulation findings against phantom and in vitro results. PWI depicted and tracked the pulse wave propagation along the abdominal wall of canine aorta in vitro in sequential Radio-Frequency (RF) ultrasound frames and estimates the PWV in the imaged wall. The same system was also used to image multiple polyacrylamide phantoms, mimicking the canine measurements as well as modeling softer and stiffer walls. Finally, the model parameters from the canine and phantom studies were used to perform 3D two-way coupled FSI simulations of pulse wave propagation and estimate the PWV. The simulation results were found to correlate well with the corresponding Moens-Korteweg equation. A high linear correlation was also established between PWV² and E measurements using the combined simulation and experimental findings (R² =  0.98) confirming the relationship established by the aforementioned equation.

A set of 4D pediatric XCAT reference phantoms for multimodality research

International Nuclear Information System (INIS)

Norris, Hannah; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P.; Minhas, Anum; Frush, D.; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

2014-01-01

Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

A set of 4D pediatric XCAT reference phantoms for multimodality research

Energy Technology Data Exchange (ETDEWEB)

Norris, Hannah, E-mail: Hannah.norris@duke.edu; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Minhas, Anum; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2014-03-15

Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

Comparison of the ANSI, RSD, KKH, and BRMD thyroid-neck phantoms for 125I thyroid monitoring.

Science.gov (United States)

Kramer, G H; Olender, G; Vlahovich, S; Hauck, B M; Meyerhof, D P

1996-03-01

The Human Monitoring Laboratory, which acts as the Canadian National Calibration Reference Centre for In Vivo Monitoring, has determined the performance characteristics of four thyroid phantoms for 125I thyroid monitoring. The phantoms were a phantom built to the specifications of the American National Standards Institute Standard N44.3; the phantom available from Radiology Support Devices; the phantom available from Kyoto Kagaku Hyohon; the phantom manufactured by the Human Monitoring Laboratory and known as the BRMD phantom. The counting efficiencies of the phantoms for 125I were measured at different phantom-to-detector distances. The anthropomorphic characteristics of the phantoms have been compared with the average man parameters. It was concluded that the BRMD, American National Standards Institute, and Radiology Support Devices phantoms have the same performance characteristics when the neck-to-detector distances are greater than 12 cm and all phantoms are essentially equivalent at 30 cm or more. The Kyoto Kagaku Hyohon phantom showed lower counting efficiencies at phantom-to-detector distances less than 30 cm. This was attributed to the design of the phantom. This study has also shown that the phantom need not be highly anthropomorphic provided the calibration is not performed at short neck-detector distances. Indeed, it might be possible to use t simple point source of 125I placed behind a 1.5 cm block of lucite at neck detector distances of 12 cm or more.

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.

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)

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

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)

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)

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.

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.

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.

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...

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

Control volume based hydrocephalus research; a phantom study

Science.gov (United States)

Cohen, Benjamin; Voorhees, Abram; Madsen, Joseph; Wei, Timothy

2009-11-01

Hydrocephalus is a complex spectrum of neurophysiological disorders involving perturbation of the intracranial contents; primarily increased intraventricular cerebrospinal fluid (CSF) volume and intracranial pressure are observed. CSF dynamics are highly coupled to the cerebral blood flows and pressures as well as the mechanical properties of the brain. Hydrocephalus, as such, is a very complex biological problem. We propose integral control volume analysis as a method of tracking these important interactions using mass and momentum conservation principles. As a first step in applying this methodology in humans, an in vitro phantom is used as a simplified model of the intracranial space. The phantom's design consists of a rigid container filled with a compressible gel. Within the gel a hollow spherical cavity represents the ventricular system and a cylindrical passage represents the spinal canal. A computer controlled piston pump supplies sinusoidal volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity and volume change as functions of time. Independent pressure measurements and momentum flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients and normal individuals. Flow and pressure measurements on the flow phantom will be presented through the control volume framework.

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 ...

A Unified Model of Phantom Energy and Dark Matter

Directory of Open Access Journals (Sweden)

Douglas Singleton

2008-01-01

Full Text Available To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/ ho <-1/3$. This form of mass-energy leads to accelerated expansion. An extreme form of dark energy, called phantom energy, has been proposed which has $w=p/ ho <-1$. This possibility is favored by the observational data. The simplest model for phantom energy involves the introduction of a scalar field with a negative kinetic energy term. Here we show that theories based on graded Lie algebras naturally have such a negative kinetic energy and thus give a model for phantom energy in a less ad hoc manner. We find that the model also contains ordinary scalar fields and anti-commuting (Grassmann vector fields which act as a form of two component dark matter. Thus from a gauge theory based on a graded algebra we naturally obtained both phantom energy and dark matter.

Development of a phantom for quality control of radiosurgery

International Nuclear Information System (INIS)

Scheidegger Soboll, D.; Reuters Schelin, H.

2008-01-01

The aim of this work was to build a phantom for quality control of stereotactic radiosurgery on linear accelerators. The outward appearance is a translucent human head filled with water and enclosing an insert with test objects of known shapes. The phantom was submitted to computerized tomography, magnetic resonance imaging and angiography exams, in order to perform a radiosurgery planning. Contours of the internal structures on the therapy planning system were drawn over the MRI images. Through the image fusion of CT and MRI, the contour data was transferred to CT images. Stereotactic registration of CT and angiography was made. One isocenter treatment was created, and using the stereotactic coordinates given by the therapy planning system, the phantom was placed on a linac. X-ray images were performed in order to verify the final positioning of the planned isocenter. In the whole process the phantom showed usefulness and adequacy for the positioning quality control of stereotactic radiosurgery with linacs, according to the main documents concerning the issue. (author)

Realistic torso phantom for calibration of in-vivo transuranic-nuclide counting facilities

Energy Technology Data Exchange (ETDEWEB)

Shirotani, Takashi

1988-11-01

A realistic torso phantom with average body size of Japanese adult males has been developed for the calibration of counting systems used for in-vivo measurements of plutonium and other actinides. The phantom contains removable model organs (lungs, liver, kidneys and heart), model trachea and artificial rib cage, and also includes chest plates that can be placed over the chest to simulate wide range adipose/muscle ratio in the human chest. Tissue substitutes used in the phantom were made of polyurethane with different concentrations of ester of phosphoric acid. Model lungs were made of foamed polyurethane with small quantities of the additive, and the artificial rib cage was made of epoxy resin with calcium carbonate. The experimental data have shown that the phantom can be used as a standard phantom for the calibration.

Phantom study of PET/CT guided delineation of radiation therapy volume

International Nuclear Information System (INIS)

Lin Lin; Zheng Rong; Wang Yibin; Geng Jianhua; Wu Ning; Zhao Ping

2012-01-01

Objective: To propose a model-based method for calculating the threshold in GTV determination by 18 F-FDG PET in a phantom study. Methods: A phantom was constructed of a 9 L cylindrical tank.Glass spheres with volumes ranging from 0.5 to 16 ml (0.5, 1, 2, 4, 8 and 16 ml) were suspended within the tank. The six spheres were filled with an identical concentration of FDG (203.5 MBq/L) and suspended within 3 different background baths of FDG (6.179, 16.021, 0 MBq/L) solutions, creating 3 target-to-background ratios of 32.96 : 1, 12.69 : 1 and target to zero background. A linear regressive function was constructed which represented the relationship between the threshold and the average activity concentration of the target. A 40% of maximum intensity threshold and the linear regressive function method were applied to define the spheres filled with 18 F-FDG. The volume differences between the two methods and the true volumes of the spheres were compared with t-test. Results: The linear regressive function model was derived as:threshold =(mean target concentration + 2.6227)/1.9752. The results indicated that a smaller deviation occurred when the function was utilized to estimate the volumes of the phantoms as compared to the 40% of maximum intensity threshold method, but there were no significant differences between them (t=0.306, P>0.05). The effect of the linear regressive function on volume was such that when the phantom sphere volumes were ≥ 1 ml, the average deviation between the defined volumes and the true volumes of phantoms was 1.01%; but when the phantom sphere volume was 0.5 ml, the average deviation was 9.53%. When the 40% of maximum intensity threshold method was applied to define the phantom spheres of volume ≥2 ml, the average deviation between the defined volumes and the true volumes of phantoms was -4.62%; but, the average deviation of that was 19.9% when the volumes of spheres were 0.5 and 1 ml. When the linear regressive function was applied to

Development of a high resolution voxelised head phantom for medical physics applications.

Science.gov (United States)

Giacometti, V; Guatelli, S; Bazalova-Carter, M; Rosenfeld, A B; Schulte, R W

2017-01-01

Computational anthropomorphic phantoms have become an important investigation tool for medical imaging and dosimetry for radiotherapy and radiation protection. The development of computational phantoms with realistic anatomical features contribute significantly to the development of novel methods in medical physics. For many applications, it is desirable that such computational phantoms have a real-world physical counterpart in order to verify the obtained results. In this work, we report the development of a voxelised phantom, the HIGH_RES_HEAD, modelling a paediatric head based on the commercial phantom 715-HN (CIRS). HIGH_RES_HEAD is unique for its anatomical details and high spatial resolution (0.18×0.18mm 2 pixel size). The development of such a phantom was required to investigate the performance of a new proton computed tomography (pCT) system, in terms of detector technology and image reconstruction algorithms. The HIGH_RES_HEAD was used in an ad-hoc Geant4 simulation modelling the pCT system. The simulation application was previously validated with respect to experimental results. When compared to a standard spatial resolution voxelised phantom of the same paediatric head, it was shown that in pCT reconstruction studies, the use of the HIGH_RES_HEAD translates into a reduction from 2% to 0.7% of the average relative stopping power difference between experimental and simulated results thus improving the overall quality of the head phantom simulation. The HIGH_RES_HEAD can also be used for other medical physics applications such as treatment planning studies. A second version of the voxelised phantom was created that contains a prototypic base of skull tumour and surrounding organs at risk. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Absorbed fractions in a voxel-based phantom calculated with the MCNP-4B code.

Science.gov (United States)

Yoriyaz, H; dos Santos, A; Stabin, M G; Cabezas, R

2000-07-01

A new approach for calculating internal dose estimates was developed through the use of a more realistic computational model of the human body. The present technique shows the capability to build a patient-specific phantom with tomography data (a voxel-based phantom) for the simulation of radiation transport and energy deposition using Monte Carlo methods such as in the MCNP-4B code. MCNP-4B absorbed fractions for photons in the mathematical phantom of Snyder et al. agreed well with reference values. Results obtained through radiation transport simulation in the voxel-based phantom, in general, agreed well with reference values. Considerable discrepancies, however, were found in some cases due to two major causes: differences in the organ masses between the phantoms and the occurrence of organ overlap in the voxel-based phantom, which is not considered in the mathematical phantom.

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.

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

Numerical modeling for an electric-field hyperthermia applicator

Science.gov (United States)

Wu, Te-Kao; Chou, C. K.; Chan, K. W.; Mcdougall, J.

1993-01-01

Hyperthermia, in conjunction with radiation and chemotherapy for treatment of cancers, is an area of current concern. Experiments have shown that hyperthermia can increase the potency of many chemotherapy drugs and the effectiveness of radiation for treating cancer. A combination of whole body or regional hyperthermia with chemotherapy or radiation should improve treatment results. Conventional methods for inducing whole body hyperthermia, such as exposing a patient in a radiant cabinet or under a hot water blanket, conduct heat very slowly from the skin to the body core. Thus a more efficient system, such as the three-plate electric-field hyperthermia applicator (EHA), is developed. This three-plate EHA has one top plate over and two lower plates beneath the patient. It is driven at 27.12 MHz with 500 Watts through a matching circuit. Using this applicator, a 50 kg pig was successfully heated to 42 C within 45 minutes. However, phantom and animal studies have indicated non-uniform heating near the side of the body. In addition, changes in the size and distance between the electrode plates can affect the heating (or electromagnetic field) pattern. Therefore, numerical models using the method of moments (MOM) or the finite difference time domain (FDTD) technique are developed to optimize the heating pattern of this EHA before it is used for human trials. The accuracy of the numerical modeling has been achieved by the good agreement between the MOM and FDTD results for the three-plate EHA without a biological body. The versatile FDTD technique is then applied to optimize the EHA design with a human body. Both the numerical and measured data in phantom blocks will be presented. The results of this study will be used to design an optimized system for whole body or regional hyperthermia.

Noncontact ultrasound imaging applied to cortical bone phantoms.

Science.gov (United States)

Bulman, J B; Ganezer, K S; Halcrow, P W; Neeson, Ian

2012-06-01

The purpose of this paper was to take the first steps toward applying noncontact ultrasound (NCU) to the tasks of monitoring osteoporosis and quantitative ultrasound imaging (QUS) of cortical bone. The authors also focused on the advantages of NCU, such as its lack of reliance on a technologist to apply transducers and a layer of acoustical coupling gel, the ability of the transducers to operate autonomously as specified by preprogrammed software, and the likely reduction in statistical and systematic errors associated with the variability in the pressure applied by the clinician to the transmitting transducer that NCU might provide. The authors also undertook this study in order to find additional applications of NCU beyond its past limited usage in assessing the severity of third degree burns. A noncontact ultrasound imaging system using a pair of specially designed broadband, 1.5 MHz noncontact piezoelectric transducers and cortical bone phantoms, were used to determine bone mineral density (BMD), speed of sound (SOS), integrated response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and two reflection paths, and a digital signal processor were also used in the collection of data from phantoms of nominal mass densities that varied from 1.17 to 2.25 g/cm(3) and in bone mineral density from 0 to 1.7 g/cm(3). Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 17 phantoms, and methods for quantifying and minimizing sources of systematic errors were outlined. The BMD of the phantom sets extended through most of the in vivo range found in cortical bone. A total of 16-20 repeated measurements of the SOS, thickness, and IR for the phantom set that were conducted over a period of several months showed a small variation in the range of measurements of ±1%-2%. These NCU data were shown to be in agreement with similar results using contact ultrasound to be within 1%-2%. Transmittance

Influence of the PMMA and the ISO slab phantom for calibrating personal dosemeters

International Nuclear Information System (INIS)

Ginjaume, M.; Ortega, X.; Barbosa, A.

2000-01-01

Wide agreement has been achieved among the main Bodies and Organisations involved in standardisation of radiation protection, related to the operational quantities for personal dosimetry. Since their definition in 1985, several reports have been published to clarify and define the experimental set up to be used for the calibration of dosemeters in terms of the above-mentioned quantities. Among these lines, ICRU 47 has listed five different phantoms that are used for calibration and whose results were accurate, within accepted uncertainties. However, to achieve uniformity in calibration procedures, the 30 cm x 30 cm x 15 cm PMMA slab phantom was recommended. The secondary calibration Laboratory from the Institut de Techniques Energetiques at the Technical University of Catalonia (UPC) agreed with the Spanish Nacional Laboratory to adopt the recommended PMMA phantom but to improve the accuracy of the calibration procedure, by introducing a correction factor for backscatter differences in a PMMA and an ICRU slab phantom. Such corrections were of the order of 8% for the low-energy X-ray qualities. Recently, ISO in ISO 4037-3, has proposed the ISO water slab phantom which consists of a 30 cm x 30 cm x 15 cm water phantom with PMMA walls (front wall 2.5 mm thick). This new phantom could be substituted by the above mentioned PMMA phantom for radiation qualities with mean energy equal or above that of 137 Cs. The aim of this work is to compare the influence of both phantoms when calibrating personal dosemeters with photons. A set of four TL personal dosemeters that are used in the UPC personal dosimetry Service and an electronic personal dosemeter (SIEMENS EPD-2) were calibrated in terms of H p (10) and H p (0.07) using the two proposed phantoms. Calibration factors for ISO X-ray narrow spectra, 137 Cs and 60 Co were experimentally obtained for each phantom and compared. In the TL measurements, differences were found to be within TL statistical uncertainty, provided that a

Radiological equipment analyzed by specific developed phantoms and software

International Nuclear Information System (INIS)

Soto, M.; Campayo, J. M.; Mayo, P.; Verdu, G.; Rodenas, F.

2010-10-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

Radiological equipment analyzed by specific developed phantoms and software

Energy Technology Data Exchange (ETDEWEB)

Soto, M.; Campayo, J. M. [Logistica y Acondicionamientos Industriales SAU, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Mayo, P. [TITANIA Servicios Tecnologicos SL, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Verdu, G.; Rodenas, F., E-mail: m.soto@lainsa.co [ISIRYIM Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia (Spain)

2010-10-15

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

Investigation of heat distribution during magnetic heating treatment using a polyurethane–ferrofluid phantom-model

International Nuclear Information System (INIS)

Henrich, F.; Rahn, H.; Odenbach, S.

2014-01-01

Magnetic heating treatment can be used as an adjuvant treatment for cancer therapy. In this therapy, magnetic nanoparticles are enriched inside the tumour and exposed to an alternating magnetic field. Due to magnetic losses the temperature in the tumour rises. The resulting temperature profile inside the tumour is useful for the therapeutic success. In this context heat transfer between tissue with nanoparticles and tissue without nanoparticles is a highly important feature which is actually not understood in detail. In order to investigate this, a phantom has been created which can be used to measure the temperature profile around a region enriched with magnetic nanoparticles. This phantom is composed of a material, which has similar thermal conductivity as human tissue. A tempered water bath surrounds the phantom to establish a constant surrounding temperature simulating the heat sink provided by the human body in a real therapeutic application. It has been found that even at a low concentration of magnetic nanoparticles around 13 mg/ml, sufficient heating of the enriched region can be achieved. Moreover it has been observed that the temperature drops rapidly in the material surrounding the enriched region. Corresponding numerical investigations provide a basis for future recalculations of the temperature inside the tumour using temperature data obtained in the surrounding tissue. - Highlights: • The temperature profile by magnetic hyperthermia was examined. • A model was built to get a deeper understanding of the temperature profile. • The temperature profile of the model inside magnetic fields was measured. • Based on the model a simulation of the temperature profile was performed. • The simulated temperature profile agreed well with the measured profile

TU-H-206-02: Novel Linearly-Filled Derenzo PET Phantom Design

International Nuclear Information System (INIS)

Graves, S; Cox, B; Valdovinos, H; Jeffery, J; Eliceiri, K; Barnhart, T; Nickles, R; Farhoud, M

2016-01-01

Purpose: To design a linearly-filled Derenzo positron emission tomography (PET) phantom, eliminating the extraneous radioisotope volumes in a conventional reservoir-type design. This activity reduction combined with the elimination of bubbles in smaller phantom channels would significantly reduce personnel dose, radioisotope cost, and would improve image quality by reducing out-of-slice activity scatter. Methods: A computer-aided design (CAD) was created of a modular Derenzo phantom consisting of three phantom layers with gaskets between the layers. The central piece contains the active pattern volume and channels connecting adjacent rods in a serpentine pattern. The two end-pieces contained an inlet and an outlet for filling purposes. Phantom prototypes were 3D printed on a Viper Si2 stereolithography machine. The two gaskets were fabricated from silicon sheets using a PLS 6.75 laser cutter. Phantoms were held together by pass-through glass-filled nylon bolts and nuts. Phantoms were filled with "5"2Mn, "6"4Cu, "7"4Br, and "1"2"4I for testing, and were imaged on a Siemens Inveon MicroPET scanner. Results: Four phantom prototypes were constructed using male Leur Lock fittings for inlet/outlet ports. 3D printed layers were sanded to ensure proper coupling to the silicon gaskets. The filling volume for each prototype was approximately 2.4 mL. The filling process was found to be rapid, leak-tight, and with minimal back-pressure. PET images were reconstructed by OSEM3D, and axial slices along the phantom pattern length were averaged to provide final images. Image distortion was isotope dependent with "5"2Mn and "6"4Cu having the least distortion and "1"2"4I having the most distortion. Conclusion: These results indicate that the linearlyfilled Derenzo design improves on conventional reservoir-type designs by eliminating potential bubbles in small channels and by reducing activity level, radioisotope volume, radioisotope cost, personnel dose, filling time, and out

Fabrication of a phantom and its application for checking gamma camera performance

International Nuclear Information System (INIS)

Yesmin, S; Ahmad, G. U.; Afroz, S.; Hossain, S.; Rashid, H.

2004-01-01

The primary aim of the present work is to fabricate a total performance phantom, which could be used for checking the performance characteristics of gamma camera. The phantom was locally fabricated at machine shop of Bangladesh University of Engineering and Technology (BUET) and used for checking the performance characteristics of gamma camera LF-61 of Centre for Nuclear Medicine and Ultrasound, Dhaka. With 10 mCi of Tc-99m, imaging of the phantom acquired with a reasonable counts. The image was inspected physically for evaluation of the camera performances. The visual inspection of the phantom image revealed that the performance characteristics like: spatial resolution, linearity, uniformity and lesion detection capability of the gamma camera could clearly be evaluated with reasonable acceptance level. This phantom is expected to be useful for checking performance characteristics of SPECT system as well. (author)

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.

A new head phantom with realistic shape and spatially varying skull resistivity distribution.

Science.gov (United States)

Li, Jian-Bo; Tang, Chi; Dai, Meng; Liu, Geng; Shi, Xue-Tao; Yang, Bin; Xu, Can-Hua; Fu, Feng; You, Fu-Sheng; Tang, Meng-Xing; Dong, Xiu-Zhen

2014-02-01

Brain electrical impedance tomography (EIT) is an emerging method for monitoring brain injuries. To effectively evaluate brain EIT systems and reconstruction algorithms, we have developed a novel head phantom that features realistic anatomy and spatially varying skull resistivity. The head phantom was created with three layers, representing scalp, skull, and brain tissues. The fabrication process entailed 3-D printing of the anatomical geometry for mold creation followed by casting to ensure high geometrical precision and accuracy of the resistivity distribution. We evaluated the accuracy and stability of the phantom. Results showed that the head phantom achieved high geometric accuracy, accurate skull resistivity values, and good stability over time and in the frequency domain. Experimental impedance reconstructions performed using the head phantom and computer simulations were found to be consistent for the same perturbation object. In conclusion, this new phantom could provide a more accurate test platform for brain EIT research.

Anthropomorphic Phantoms for Confirmation of Linear Accelerator-Based Small Animal Irradiation.

Science.gov (United States)

Perks, Julian R; Lucero, Steven; Monjazeb, Arta M; Li, Jian Jian

2015-03-01

Three dimensional (3D) scanning and printing technology is utilized to create phantom models of mice in order to assess the accuracy of ionizing radiation dosing from a clinical, human-based linear accelerator. Phantoms are designed to simulate a range of research questions, including irradiation of lung tumors and primary subcutaneous or orthotopic tumors for immunotherapy experimentation. The phantoms are used to measure the accuracy of dose delivery and then refine it to within 1% of the prescribed dose.

A low-cost phantom for simple routine testing of single photon emission computed tomography (SPECT) cameras

International Nuclear Information System (INIS)

Ng, A.H.; Ng, K.H.; Dharmendra, H.; Perkins, A.C.

2009-01-01

A simple sphere test phantom has been developed for routine performance testing of SPECT systems in situations where expensive commercial phantoms may not be available. The phantom was based on a design with six universal syringe hubs set in the frame to support a circular array of six glass blown spheres of different sizes. The frame was then placed into a water-filled CT abdomen phantom and scanned with a triple head camera system (Philips IRIX TM , USA). Comparison was made with a commercially available phantom (Deluxe Jaszczak phantom). Whereas the commercial phantom demonstrates cold spot resolution, an important advantage of the sphere test phantom was that hot spot resolution could be easily measured using almost half (370 MBq) of the activity recommended for use in the commercial phantom. Results showed that the contrast increased non-linearly with sphere volume and radionuclide concentration. The phantom was found to be suitable as an inexpensive option for daily performance tests.

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

Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom

International Nuclear Information System (INIS)

Batista Nogueira, Luciana; Lemos Silva, Hugo Leonardo; Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio

2015-01-01

This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic films EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm 2 each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the prescribed

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

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.

Viscosity-Induced Crossing of the Phantom Barrier

Directory of Open Access Journals (Sweden)

Iver Brevik

2015-09-01

Full Text Available We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region at present time t = 0 across the barrier w = −1 into the phantom region in the late universe. The phantom barrier is accordingly not a sharp mathematical divide, but rather a fuzzy concept. We also calculate the limiting forms of various thermodynamical quantities, including the rate of entropy production, for a dark energy fluid near the future Big Rip singularity.

In Vivo Optical Imaging for Targeted Drug Kinetics and Localization for Oral Surgery and Super-Resolution, Facilitated by Printed Phantoms

Science.gov (United States)

Bentz, Brian Z.

Many human cancer cell types over-express folate receptors, and this provides an opportunity to develop targeted anti-cancer drugs. For these drugs to be effective, their kinetics must be well understood in vivo and in deep tissue where tumors occur. We demonstrate a method for imaging these parameters by incorporating a kinetic compartment model and fluorescence into optical diffusion tomography (ODT). The kinetics were imaged in a live mouse, and found to be in agreement with previous in vitro studies, demonstrating the validity of the method and its feasibility as an effective tool in preclinical drug development studies. Progress in developing optical imaging for biomedical applications requires customizable and often complex objects known as "phantoms" for testing and evaluation. We present new optical phantoms fabricated using inexpensive 3D printing methods with multiple materials, allowing for the placement of complex inhomogeneities in heterogeneous or anatomically realistic geometries, as opposed to previous phantoms which were limited to simple shapes formed by molds or machining. Furthermore, we show that Mie theory can be used to design the optical properties to match a target tissue. The phantom fabrication methods are versatile, can be applied to optical imaging methods besides diffusive imaging, and can be used in the calibration of live animal imaging data. Applications of diffuse optical imaging in the operating theater have been limited in part due to computational burden. We present an approach for the fast localization of arteries in the roof of the mouth that has the potential to reduce complications. Furthermore, we use the extracted position information to fabricate a custom surgical guide using 3D printing that could protect the arteries during surgery. The resolution of ODT is severely limited by the attenuation of high spatial frequencies. We present a super-resolution method achieved through the point localization of fluorescent

Construction of voxel head phantom and application to BNCT dose calculation

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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.

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

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.

SU-G-206-05: A Comparison of Head Phantoms Used for Dose Determination in Imaging Procedures

Energy Technology Data Exchange (ETDEWEB)

Xiong, Z; Vijayan, S; Kilian-Meneghin, J; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

2016-06-15

Purpose: To determine similarities and differences between various head phantoms that might be used for dose measurements in diagnostic imaging procedures. Methods: We chose four frequently used anthropomorphic head phantoms (SK-150, PBU-50, RS-240T and Alderson Rando), a computational patient phantom (Zubal) and the CTDI head phantom for comparison in our study. We did a CT scan of the head phantoms using the same protocol and compared their dimensions and CT numbers. The scan data was used to calculate dose values for each of the phantoms using EGSnrc Monte Carlo software. An .egsphant file was constructed to describe these phantoms using a Visual C++ program for DOSXYZnrc/EGSnrc simulation. The lens dose was calculated for a simulated CBCT scan using DOSXYZnrc/EGSnrc and the calculated doses were validated with measurements using Gafchromic film and an ionization chamber. Similar calculations and measurements were made for PA radiography to investigate the attenuation and backscatter differences between these phantoms. We used the Zubal phantom as the standard for comparison since it was developed based on a CT scan of a patient. Results: The lens dose for the Alderson Rando phantom is around 9% different than the Zubal phantom, while the lens dose for the PBU-50 phantom was about 50% higher, possibly because its skull thickness and the density of bone and soft tissue are lower than anthropometric values. The lens dose for the CTDI phantom is about 500% higher because of its totally different structure. The entrance dose profiles are similar for the five anthropomorphic phantoms, while that for the CTDI phantom was distinctly different. Conclusion: The CTDI and PBU-50 head phantoms have substantially larger lens dose estimates in CBCT. The other four head phantoms have similar entrance dose with backscatter hence should be preferred for dose measurement in imaging procedures of the head. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems

Development of age-specific Japanese physical phantoms for dose evaluation in infant CT examinations

International Nuclear Information System (INIS)

Yamauchi-Kawaura, C.; Fujii, K.; Imai, K.; Ikeda, M.; Akahane, K.; Obara, S.; Yamauchi, M.; Narai, K.; Katsu, T.

2016-01-01

Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdomino-pelvic CT examinations. (authors)

Construction of Korean adult voxel phantoms for radiation dosimetry and their applications

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Lee, Choon Sik

2002-08-15

Although contribution of the MIRD-type mathematical anthropomorphic phantoms to computational radiation dosimetry, especially in determining the effective dose to the exposed personnel, is very significant, there remain some questions on possible deviation in the resulting dosimetric quantities from the true values. This is particularly the case for those organ or tissues having complicated geometry difficult to model with simple geometrical body elements. As an alternative approach to resolve the problem, there have been efforts to use voxel phantoms, which can very precisely describe both the external shape and the internal organs by virtue of fast advances in medical imaging technology as well as in computing power. In this study, Korean adult male and female voxel phantoms were constructed by processing whole-body MR images of healthy volunteers who belong to middle group of Korean in height and weight. Organs and tissues on tomographic images were manually segmented and indexed using the graphic software PL-400 . Due to limited resolution of the raw MR images, voxels of rather large size, 2 mmx2 mmx8 mm for the woman and 2mmx2mmx10mm for the man, were used. The resulting male and female voxel phantoms were named KRMAN and KRWOMAN, respectively. To assess utility of the voxel phatoms, calculations were carried out with the Monte Carlo code MCNP4B for two illustrative problems. A program VOXELMAKER1.0 was developed to convert the voxel phantom data into MCNP geometry input format. In the first example, organ equivalent doses and effective doses were evaluated for phantoms in broad parallel photon fields of different energies and directions and were compared to corresponding values given in ICRP 74 which were derived with the MIRD-type phantoms. No significant deviations between MIRD and voxel phantoms were found in the effective doses. Significant differences up to around factor of 2, however, were observed in organ equivalent doses for some organs including

Development of a three-dimensionally movable phantom system for dosimetric verifications

International Nuclear Information System (INIS)

Nakayama, Hiroshi; Mizowaki, Takashi; Narita, Yuichiro; Kawada, Noriyuki; Takahashi, Kunio; Mihara, Kazumasa; Hiraoka, Masahiro

2008-01-01

The authors developed a three-dimensionally movable phantom system (3D movable phantom system) which can reproduce three-dimensional movements to experimentally verify the impact of radiotherapy treatment-related movements on dose distribution. The phantom system consists of three integrated components: a three-dimensional driving mechanism (3D driving mechanism), computer control system, and phantoms for film dosimetry. The 3D driving mechanism is a quintessential part of this system. It is composed of three linear-motion tables (single-axis robots) which are joined orthogonally to each other. This mechanism has a motion range of 100 mm, with a maximum velocity of 200 mm/s in each dimension, and 3D motion ability of arbitrary patterns. These attributes are sufficient to reproduce almost all organ movements. The positional accuracy of this 3D movable phantom system in a state of geostationary is less than 0.1 mm. The maximum error in terms of the absolute position on movement was 0.56 mm. The positional reappearance error on movement was up to 0.23 mm. The observed fluctuation of time was 0.012 s in the cycle of 4.5 s of oscillation. These results suggested that the 3D movable phantom system exhibited a sufficient level of accuracy in terms of geometry and timing to reproduce interfractional organ movement or setup errors in order to assess the influence of these errors on high-precision radiotherapy such as stereotactic irradiation and intensity-modulated radiotherapy. In addition, the authors 3D movable phantom system will also be useful in evaluating the adequacy and efficacy of new treatment techniques such as gating or tracking radiotherapy

WE-D-303-01: Development and Application of Digital Human Phantoms

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Segars, P. [Duke University, Durham, NC (United States)

2015-06-15

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems.

WE-D-303-01: Development and Application of Digital Human Phantoms

International Nuclear Information System (INIS)

Segars, P.

2015-01-01

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems

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

Development of mathematical pediatric phantoms for internal dose calculations: designs, limitations, and prospects

International Nuclear Information System (INIS)

Cristy, M.

1980-01-01

Mathematical phantoms of the human body at various ages are employed with Monte Carlo radiation transport codes for calculation of photon specific absorbed fractions. The author has developed a pediatric phantom series based on the design of the adult phantom, but with explicit equations for each organ so that organ sizes and marrow distributions could be assigned properly. Since the phantoms comprise simple geometric shapes, predictive dose capability is limited when geometry is critical to the calculation. Hence, there is a demand for better phantom design in situations where geometry is critical, such as for external irradiation or for internal emitters with low energy photons. Recent advances in computerized axial tomography (CAT) present the potential for derivation of anatomical information, which is so critical to development of phantoms, and ongoing developmental work on compuer architecture to handle large arrays for Monte Carlo calculations should make complex-geometry dose calculations economically feasible within this decade

Fuzzy classification of phantom parent groups in an animal model

Directory of Open Access Journals (Sweden)

Fikse Freddy

2009-09-01

Full Text Available Abstract Background Genetic evaluation models often include genetic groups to account for unequal genetic level of animals with unknown parentage. The definition of phantom parent groups usually includes a time component (e.g. years. Combining several time periods to ensure sufficiently large groups may create problems since all phantom parents in a group are considered contemporaries. Methods To avoid the downside of such distinct classification, a fuzzy logic approach is suggested. A phantom parent can be assigned to several genetic groups, with proportions between zero and one that sum to one. Rules were presented for assigning coefficients to the inverse of the relationship matrix for fuzzy-classified genetic groups. This approach was illustrated with simulated data from ten generations of mass selection. Observations and pedigree records were randomly deleted. Phantom parent groups were defined on the basis of gender and generation number. In one scenario, uncertainty about generation of birth was simulated for some animals with unknown parents. In the distinct classification, one of the two possible generations of birth was randomly chosen to assign phantom parents to genetic groups for animals with simulated uncertainty, whereas the phantom parents were assigned to both possible genetic groups in the fuzzy classification. Results The empirical prediction error variance (PEV was somewhat lower for fuzzy-classified genetic groups. The ranking of animals with unknown parents was more correct and less variable across replicates in comparison with distinct genetic groups. In another scenario, each phantom parent was assigned to three groups, one pertaining to its gender, and two pertaining to the first and last generation, with proportion depending on the (true generation of birth. Due to the lower number of groups, the empirical PEV of breeding values was smaller when genetic groups were fuzzy-classified. Conclusion Fuzzy

Population of 224 realistic human subject-based computational breast phantoms

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Erickson, David W. [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Wells, Jered R., E-mail: jered.wells@duke.edu [Clinical Imaging Physics Group and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Sturgeon, Gregory M. [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Samei, Ehsan [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Physics, Electrical and Computer Engineering, and Biomedical Engineering, and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Dobbins, James T. [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Physics and Biomedical Engineering and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Segars, W. Paul [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Lo, Joseph Y. [Department of Radiology and Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Electrical and Computer Engineering and Biomedical Engineering and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States)

2016-01-15

Purpose: To create a database of highly realistic and anatomically variable 3D virtual breast phantoms based on dedicated breast computed tomography (bCT) data. Methods: A tissue classification and segmentation algorithm was used to create realistic and detailed 3D computational breast phantoms based on 230 + dedicated bCT datasets from normal human subjects. The breast volume was identified using a coarse three-class fuzzy C-means segmentation algorithm which accounted for and removed motion blur at the breast periphery. Noise in the bCT data was reduced through application of a postreconstruction 3D bilateral filter. A 3D adipose nonuniformity (bias field) correction was then applied followed by glandular segmentation using a 3D bias-corrected fuzzy C-means algorithm. Multiple tissue classes were defined including skin, adipose, and several fractional glandular densities. Following segmentation, a skin mask was produced which preserved the interdigitated skin, adipose, and glandular boundaries of the skin interior. Finally, surface modeling was used to produce digital phantoms with methods complementary to the XCAT suite of digital human phantoms. Results: After rejecting some datasets due to artifacts, 224 virtual breast phantoms were created which emulate the complex breast parenchyma of actual human subjects. The volume breast density (with skin) ranged from 5.5% to 66.3% with a mean value of 25.3% ± 13.2%. Breast volumes ranged from 25.0 to 2099.6 ml with a mean value of 716.3 ± 386.5 ml. Three breast phantoms were selected for imaging with digital compression (using finite element modeling) and simple ray-tracing, and the results show promise in their potential to produce realistic simulated mammograms. Conclusions: This work provides a new population of 224 breast phantoms based on in vivo bCT data for imaging research. Compared to previous studies based on only a few prototype cases, this dataset provides a rich source of new cases spanning a wide range

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)

Comparison of low-contrast detectability between two CT reconstruction algorithms using voxel-based 3D printed textured phantoms.

Science.gov (United States)

Solomon, Justin; Ba, Alexandre; Bochud, François; Samei, Ehsan

2016-12-01

To use novel voxel-based 3D printed textured phantoms in order to compare low-contrast detectability between two reconstruction algorithms, FBP (filtered-backprojection) and SAFIRE (sinogram affirmed iterative reconstruction) and determine what impact background texture (i.e., anatomical noise) has on estimating the dose reduction potential of SAFIRE. Liver volumes were segmented from 23 abdominal CT cases. The volumes were characterized in terms of texture features from gray-level co-occurrence and run-length matrices. Using a 3D clustered lumpy background (CLB) model, a fitting technique based on a genetic optimization algorithm was used to find CLB textures that were reflective of the liver textures, accounting for CT system factors of spatial blurring and noise. With the modeled background texture as a guide, four cylindrical phantoms (Textures A-C and uniform, 165 mm in diameter, and 30 mm height) were designed, each containing 20 low-contrast spherical signals (6 mm diameter at nominal contrast levels of ∼3.2, 5.2, 7.2, 10, and 14 HU with four repeats per signal). The phantoms were voxelized and input into a commercial multimaterial 3D printer (Object Connex 350), with custom software for voxel-based printing (using principles of digital dithering). Images of the textured phantoms and a corresponding uniform phantom were acquired at six radiation dose levels (SOMATOM Flash, Siemens Healthcare) and observer model detection performance (detectability index of a multislice channelized Hotelling observer) was estimated for each condition (5 contrasts × 6 doses × 2 reconstructions × 4 backgrounds = 240 total conditions). A multivariate generalized regression analysis was performed (linear terms, no interactions, random error term, log link function) to assess whether dose, reconstruction algorithm, signal contrast, and background type have statistically significant effects on detectability. Also, fitted curves of detectability (averaged across contrast levels

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.

Influence of different types of phantoms on the calibration of dosemeters for eye lens dosimetry

International Nuclear Information System (INIS)

Yoshitomi, H.; Kowatari, M.

2016-01-01

Both a cylinder and a slab phantom have been recommended to be used as calibration phantoms for eye lens dosimetry in the International Atomic Energy Agency TECDOC. This study describes investigations on the influence of the type of phantom on the calibration of dosemeters. In order to fulfil the purpose, backscatter radiation from practically used water-filled phantoms was evaluated by calculations and experiments. For photons, the calculations showed that the cylinder phantom had 10 % lower backscattered effect at maximum than a slab phantom, and simulated well the backscattered effect of the human head or neck to within ±10 %. The irradiation results of non-filtered optically stimulated luminescence and radio-photoluminescence glass dosemeters indicated that the differences of the calibration factors between the two types of phantoms were up to 20 and 10 %, respectively, reflecting the response to backscattered photons. For electrons, no difference was found between the two types of phantoms. (authors)

Survey of potential use of dynamic line phantom for quality control of Gamma camera

International Nuclear Information System (INIS)

Trindev, P.; Ozturk, N.

2004-01-01

Different phantoms, used to evaluate the essential for image quality parameters of gamma cameras in order to avoid artefacts, are presented. The prices are significant and it is a sensible approach to optimise the type and number of phantoms necessary for quality control. Among all phantoms the price of 'Dynamic Line Phantom' (DLP) is impressive, but it is announced to substitute several 'passive' and 'active' phantoms. The goal of this paper is to justify this statement. The programs, based on image profile are discussed in the paper and the practical uses of the different programs are given

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

Energy Technology Data Exchange (ETDEWEB)

Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Williams, Cameron H.; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2013-04-15

Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

International Nuclear Information System (INIS)

Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E.; Williams, Cameron H.; Frush, D.; Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

2013-01-01

Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest–abdomen–pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore

Design and development of an ultrasound calibration phantom and system

Science.gov (United States)

Cheng, Alexis; Ackerman, Martin K.; Chirikjian, Gregory S.; Boctor, Emad M.

2014-03-01

Image-guided surgery systems are often used to provide surgeons with informational support. Due to several unique advantages such as ease of use, real-time image acquisition, and no ionizing radiation, ultrasound is a common medical imaging modality used in image-guided surgery systems. To perform advanced forms of guidance with ultrasound, such as virtual image overlays or automated robotic actuation, an ultrasound calibration process must be performed. This process recovers the rigid body transformation between a tracked marker attached to the ultrasound transducer and the ultrasound image. A phantom or model with known geometry is also required. In this work, we design and test an ultrasound calibration phantom and software. The two main considerations in this work are utilizing our knowledge of ultrasound physics to design the phantom and delivering an easy to use calibration process to the user. We explore the use of a three-dimensional printer to create the phantom in its entirety without need for user assembly. We have also developed software to automatically segment the three-dimensional printed rods from the ultrasound image by leveraging knowledge about the shape and scale of the phantom. In this work, we present preliminary results from using this phantom to perform ultrasound calibration. To test the efficacy of our method, we match the projection of the points segmented from the image to the known model and calculate a sum squared difference between each point for several combinations of motion generation and filtering methods. The best performing combination of motion and filtering techniques had an error of 1.56 mm and a standard deviation of 1.02 mm.

Influence of lucite phantoms on calibration of dosimetric pens

International Nuclear Information System (INIS)

Oliveira, E.C.; Xavier, M.; Caldas, L.E.V.

1992-01-01

Dosimetrical pens were studied for the answer repetition and were tested in gamma radiation fields ( 60 Co and 137 Cs) in air and in front of a lucite phantom, obtaining a backscattering contribution. The medium backscattering factors were 1,053 and 1,108 for respectively 60 Co and 137 Cs. The pens were placed behind the phantom for verifying the radiation attenuation. (C.G.C.)

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

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

International Nuclear Information System (INIS)

Ehler, E; Higgins, P; Dusenbery, K

2014-01-01

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: 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. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: 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 clinical use

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

Energy Technology Data Exchange (ETDEWEB)

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

2014-06-15

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: 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. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: 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 clinical use.

Optimization of phantom backscatter thickness and lateral scatter volume for radiographic film dosimetry

International Nuclear Information System (INIS)

Srivastava, R.P.; De Wagter, C.

2012-01-01

The aim of this study is to determine the optimal backscatter thickness and lateral phantom dimension beyond the irradiated volume for the dosimetric verification with radiographic film when applying large field sizes. Polystyrene and Virtual Water™ phantoms were used to study the influence of the phantom backscatter thickness. EDR2 and XV films were used in 6 and 18 MV photon beams. The results show 11.4% and 6.4% over-response of the XV2 film when compared to the ion chamber for 6 MV 30×30 and 10×10 cm 2 field sizes, respectively, when the phantom backscatter thickness is 5 cm. For the same setup, measurements with EDR2 films indicate 8.5% and 1.7% over-response. The XV2 film response in the polystyrene phantom is about 2.0% higher than in the Virtual Water™ phantom for the 6 MV beam and 20 cm backscatter thickness. Similar results were obtained for EDR2 film. In the lateral scatter study, film response was nearly constant within 5 cm of lateral thickness and it increases when lateral thickness increases due to more multiple scatter of low energy photons. The backscatter thickness of the phantom should be kept below 7 cm for the accuracy of the film dosimetry. The lateral extension of the phantom should not be more than 5 cm from the field boundary in case of large irradiated volumes.

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...

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

On the need to revise the arm structure in stylized anthropomorphic phantoms in lateral photon irradiation geometry

International Nuclear Information System (INIS)

Lee, Choonsik; Lee, Choonik; Lee, Jai-Ki

2006-01-01

Distributions of radiation absorbed dose within human anatomy have been estimated through Monte Carlo radiation transport techniques implemented for two different classes of computational anthropomorphic phantoms: (1) mathematical equation-based stylized phantoms and (2) tomographic image-based voxel phantoms. Voxel phantoms constructed from tomographic images of real human anatomy have been actively developed since the late 1980s to overcome the anatomical approximations necessary with stylized phantoms, which themselves have been utilized since the mid 1960s. However, revisions of stylized phantoms have also been pursued in parallel to the development of voxel phantoms since voxel phantoms (1) are initially restricted to the individual-specific anatomy of the person originally imaged, (2) must be restructured on an organ-by-organ basis to conform to reference individual anatomy and (3) cannot easily represent very fine anatomical structures and tissue layers that are thinner than the voxel dimensions of the overall phantom. Although efforts have been made to improve the anatomic realism of stylized phantoms, most of these efforts have been limited to attempts to alter internal organ structures. Aside from the internal organs, the exterior shapes, and especially the arm structures, of stylized phantoms are also far from realistic descriptions of human anatomy, and may cause dosimetry errors in the calculation of organ-absorbed doses for external irradiation scenarios. The present study was intended to highlight the need to revise the existing arm structure within stylized phantoms by comparing organ doses of stylized adult phantoms with those from three adult voxel phantoms in the lateral photon irradiation geometry. The representative stylized phantom, the adult phantom of the Oak Ridge National Laboratory (ORNL) series and two adult male voxel phantoms, KTMAN-2 and VOXTISS8, were employed for Monte Carlo dose calculation, and data from another voxel phantom, VIP

Distributions of neutron and gamma doses in phantom under a mixed field

International Nuclear Information System (INIS)

Beraud-Sudreau, E.

1982-06-01

A calculation program, based on Monte Carlo method, allowed to estimate the absorbed doses relatives to the reactor primary radiation, in a water cubic phantom and in cylindrical phantoms modelized from tissue compositions. This calculation is a theoretical approach of gamma and neutron dose gradient study in an animal phantom. PIN junction dosimetric characteristics have been studied experimentally. Air and water phantom radiation doses measured by PIN junction and lithium 7 fluoride, in reactor field have been compared to doses given by dosimetry classical techniques as tissue equivalent plastic and aluminium ionization chambers. Dosimeter responses have been employed to evaluate neutron and gamma doses in plastinaut (tissue equivalent plastic) and animal (piglet). Dose repartition in the piglet bone medulla has been also determined. This work has been completed by comparisons with Doerschell, Dousset and Brown results and by neutron dose calculations; the dose distribution related to lineic energy transfer in Auxier phantom has been also calculated [fr

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)

Evaluation of non-linear adaptive smoothing filter by digital phantom

International Nuclear Information System (INIS)

Sato, Kazuhiro; Ishiya, Hiroki; Oshita, Ryosuke; Yanagawa, Isao; Goto, Mitsunori; Mori, Issei

2008-01-01

As a result of the development of multi-slice CT, diagnoses based on three-dimensional reconstruction images and multi-planar reconstruction have spread. For these applications, which require high z-resolution, thin slice imaging is essential. However, because z-resolution is always based on a trade-off with image noise, thin slice imaging is necessarily accompanied by an increase in noise level. To improve the quality of thin slice images, a non-linear adaptive smoothing filter has been developed, and is being widely applied to clinical use. We developed a digital bar pattern phantom for the purpose of evaluating the effect of this filter and attempted evaluation from an addition image of the bar pattern phantom and the image of the water phantom. The effect of this filter was changed in a complex manner by the contrast and spatial frequency of the original image. We have confirmed the reduced effect of image noise in the low frequency component of the image, but decreased contrast or increased quantity of noise in the image of the high frequency component. This result represents the effect of change in the adaptation of this filter. The digital phantom was useful for this evaluation, but to understand the total effect of filtering, much improvement of the shape of the digital phantom is required. (author)

Localization of the phantom force induced by the tunneling current

Science.gov (United States)

Wutscher, Thorsten; Weymouth, Alfred J.; Giessibl, Franz J.

2012-05-01

The phantom force is an apparently repulsive force, which can dominate the atomic contrast of an AFM image when a tunneling current is present. We described this effect with a simple resistive model, in which the tunneling current causes a voltage drop at the sample area underneath the probe tip. Because tunneling is a highly local process, the areal current density is quite high, which leads to an appreciable local voltage drop that in turn changes the electrostatic attraction between tip and sample. However, Si(111)-7×7 has a metallic surface state and it might be proposed that electrons should instead propagate along the surface state, as through a thin metal film on a semiconducting surface, before propagating into the bulk. In this paper, we first measure the phantom force on a sample that displays a metallic surface state [here, Si(111)-7×7] using tips with various radii. If the metallic surface state would lead to a constant electrostatic potential on the surface, we would expect a direct dependence of the phantom force with tip radius. In a second set of experiments, we study H/Si(100), a surface that does not have a metallic surface state. We conclude that a metallic surface state does not suppress the phantom force, but that the local resistance Rs has a strong effect on the magnitude of the phantom force.

Construction of Korean female voxel phantom and its application to dosimetry

Energy Technology Data Exchange (ETDEWEB)

Lee, Choon Ik

2001-08-15

A Korean female voxel phantom was constructed to overcome the limitations of anatomical description of the existing MRD-type mathematical anthropomorphic phantom and the example dose calculations were carried out for the radiation protection by using it. This whole body voxel phantom was based on the MRIs of the Korean adult female who falls into the reference Korean female group. The cross sectional human pictures from VHP of NLM was adopted for the modification and compensation of the missing MRIs of Korean adult female that include legs below upper thighs. From the gastrointestinal and respiratory organ which make obscure organ edges because of their continuing motion, the general anatomical knowledge were applied for the segmentation process. The Korean female whole body voxel phantom named in HYWOMAN is composed of 1,392,400 voxels that have width x length x height of 4mm x 4mm x 8mm for each with the total of 20 organs identified. With MDNP4B code the tissue equivalent doses were calculated for the four different energies of 0.4, 0.8, 2 and 8 MeV broad parallel gamma beam in AP, PA, LLAT and RLAT directions. The tissue equivalent doses were compared with those of ORNL adult female phantom under the same irradiation conditions. Despite of the small organ differences there could be found the considerable differences in tissue equivalent doses for some organs including thyroid, esophagus, kidneys and spleen. The cause of these discrepancies were proved to be the position of the organs in the phantom and the consequent shielding effects. With the methodology of this study, Korean reference male and female age-grouped voxel phantoms can be constructed and consequently the dosimetry system for typical Korean people is to be established.

The threshold contrast thickness evaluated with different CDMAM phantoms and software

Directory of Open Access Journals (Sweden)

Fabiszewska Ewa

2016-03-01

Full Text Available The image quality in digital mammography is described by specifying the thickness and diameter of disks with threshold visibility. The European Commission recommends the CDMAM phantom as a tool to evaluate threshold contrast visibility in digital mammography [1, 2]. Inaccuracy of the manufacturing process of CDMAM 3.4 phantoms (Artinis Medical System BV, as well as differences between software used to analyze the images, may lead to discrepancies in the evaluation of threshold contrast visibility. The authors of this work used three CDMAM 3.4 phantoms with serial numbers 1669, 1840, and 1841 and two mammography systems of the same manufacturer with an identical types of detectors. The images were analyzed with EUREF software (version 1.5.5 with CDCOM 1.6. exe file and Artinis software (version 1.2 with CDCOM 1.6. exe file. The differences between the observed thicknesses of the threshold contrast structures, which were caused by differences between the CDMAM 3.4 phantoms, were not reproduced in the same way on two mammography units of the same type. The thickness reported by the Artinis software (version 1.2 with CDCOM 1.6. exe file was generally greater than the one determined by the EUREF software (version 1.5.5 with CDCOM 1.6. exe file, but the ratio of the results depended on the phantom and diameter of the structure. It was not possible to establish correction factors, which would allow correction of the differences between the results obtained for different CDMAM 3.4 phantoms, or to correct the differences between software. Great care must be taken when results of the tests performed with different CDMAM 3.4 phantoms and with different software application are interpreted.

Construction of Korean female voxel phantom and its application to dosimetry

International Nuclear Information System (INIS)

Lee, Choon Ik

2001-08-01

A Korean female voxel phantom was constructed to overcome the limitations of anatomical description of the existing MRD-type mathematical anthropomorphic phantom and the example dose calculations were carried out for the radiation protection by using it. This whole body voxel phantom was based on the MRIs of the Korean adult female who falls into the reference Korean female group. The cross sectional human pictures from VHP of NLM was adopted for the modification and compensation of the missing MRIs of Korean adult female that include legs below upper thighs. From the gastrointestinal and respiratory organ which make obscure organ edges because of their continuing motion, the general anatomical knowledge were applied for the segmentation process. The Korean female whole body voxel phantom named in HYWOMAN is composed of 1,392,400 voxels that have width x length x height of 4mm x 4mm x 8mm for each with the total of 20 organs identified. With MDNP4B code the tissue equivalent doses were calculated for the four different energies of 0.4, 0.8, 2 and 8 MeV broad parallel gamma beam in AP, PA, LLAT and RLAT directions. The tissue equivalent doses were compared with those of ORNL adult female phantom under the same irradiation conditions. Despite of the small organ differences there could be found the considerable differences in tissue equivalent doses for some organs including thyroid, esophagus, kidneys and spleen. The cause of these discrepancies were proved to be the position of the organs in the phantom and the consequent shielding effects. With the methodology of this study, Korean reference male and female age-grouped voxel phantoms can be constructed and consequently the dosimetry system for typical Korean people is to be established

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)

A note on crossing the phantom divide in hybrid dark energy model

International Nuclear Information System (INIS)

Wei Hao; Cai Ronggen

2006-01-01

Recently a lot of attention has been given to building dark energy models in which the equation-of-state parameter w can cross the phantom divide w=-1. However, to our knowledge, these models with crossing the phantom divide only provide the possibility that w can cross -1. They do not answer another question: why crossing phantom divide occurs recently? Since in many existing models whose equation-of-state parameter can cross the phantom divide, w undulates around -1 randomly, why are we living in an epochw<-1? This can be regarded as the second cosmological coincidence problem. In this Letter, we propose a possible approach to alleviate this problem within a hybrid dark energy model

Interagency mechanical operations group numerical systems group

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-09-01

This report consists of the minutes of the May 20-21, 1971 meeting of the Interagency Mechanical Operations Group (IMOG) Numerical Systems Group. This group looks at issues related to numerical control in the machining industry. Items discussed related to the use of CAD and CAM, EIA standards, data links, and numerical control.

An Inexpensive and Easy Ultrasound Phantom: A Novel Use for SPAM.

Science.gov (United States)

Nolting, Laura; Hunt, Patrick; Cook, Thomas; Douglas, Barton

2016-04-01

Ultrasound models, commonly referred to as "phantoms," are simulation tools for ultrasound education. Commercially produced phantoms are available, but there are "homemade" alternatives such as raw poultry and gelatin molds. Precooked, processed meat, better known as SPAM (Hormel Foods Corporation, Austin, MN), can be used as an ultrasound phantom to teach several ultrasound applications. It is a versatile, hygienic, and easily manipulated medium that does not require refrigeration or preparatory work and can be easily discarded at the end of use. © 2016 by the American Institute of Ultrasound in Medicine.

Efficiency Calibration of Phantom Family for Use in Direct Bioassay of Radionuclide in the Body

International Nuclear Information System (INIS)

Kim, Ji Seok; Ha, Wi Ho; Kim, Hyun Ki; Park, Gyung Deok; Lee, Jai Ki

2008-01-01

A major source of uncertainties of in vivo bioassay using a whole body counter calibrated against a body phantom containing known radioactivities is variation of counting geometry caused by the differences in body size of the subject from that of the phantom. Phantoms such as the BOMAB phantom are based on the body size of the reference man and usually single phantom is used in usual calibration of the counter. This is because it is difficult to apply a set of phantoms having different sizes. In order to reduce the potential errors due to variation of counting geometry, use of a set of phantoms having different body-shapes have been attempted. The efficiency files are stored in the computer analyzing the measurement data and a suitable one is retrieved for the specific subject. Experimental or computational approach can be employed in generation of the efficiency files. Carlan et al. demonstrated that Monte Carlo simulations can provide acceptable efficiencies by use of the IGOR phantom family. The body size of the individual subject undergoing in vivo bioassay should be determined by an appropriate method

Synthetic digital radiographs using exposure computer models of Voxels / EGS4 Phantoms

International Nuclear Information System (INIS)

Kenned, Roberto; Vieira, Jose W.; Lima, Fernando R.A.; Loureiro, Eduardo

2008-01-01

The objective of this work is to produce synthetic digital radiographs from synthetic phantoms with the use of a Computational Model of Exposition (MCE). The literature explains a model consisted on a phantom, a Monte Carlo code and an algorithm of a radioactive source. In this work it was used the FAX phantom (Female Adult voXel), besides the EGS4 system code Eletron Shower-range version 4) and an external source, similar to that used in diagnostic radiology. The implementation of MCE creates files with information on external energy deposited in the voxels of fantoma used, here called EnergiaPorVoxel.dat. These files along with the targeted phantom (fax.sgi) worked as data entry for the DIP software (Digital Imaging Processing) to build the synthetic phantoms based on energy and the effective dose. This way you can save each slice that is the stack of pictures of these phantoms synthetics, which have been called synthetic digital radiography. Using this, it is possible to use techniques of emphasis in space to increase the contrast or elineate contours between organs and tissues. The practical use of these images is not only to allow a planning of examinations performed in clinics and hospitals and reducing unnecessary exposure to patients by error of radiographic techniques. (author)

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.

Phantom dosimetry at 15 MV conformal radiation therapy

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio P.R.; Dias, Humberto G.

2013-01-01

The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

Phantom dosimetry at 15 MV conformal radiation therapy

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio P.R.

2015-01-01

The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

A two-dimensional deformable phantom for quantitatively verifying deformation algorithms

Energy Technology Data Exchange (ETDEWEB)

Kirby, Neil; Chuang, Cynthia; Pouliot, Jean [Department of Radiation Oncology, University of California San Francisco, San Francisco, California 94143-1708 (United States)

2011-08-15

Purpose: The incorporation of deformable image registration into the treatment planning process is rapidly advancing. For this reason, the methods used to verify the underlying deformation algorithms must evolve equally fast. This manuscript proposes a two-dimensional deformable phantom, which can objectively verify the accuracy of deformation algorithms, as the next step for improving these techniques. Methods: The phantom represents a single plane of the anatomy for a head and neck patient. Inflation of a balloon catheter inside the phantom simulates tumor growth. CT and camera images of the phantom are acquired before and after its deformation. Nonradiopaque markers reside on the surface of the deformable anatomy and are visible through an acrylic plate, which enables an optical camera to measure their positions; thus, establishing the ground-truth deformation. This measured deformation is directly compared to the predictions of deformation algorithms, using several similarity metrics. The ratio of the number of points with more than a 3 mm deformation error over the number that are deformed by more than 3 mm is used for an error metric to evaluate algorithm accuracy. Results: An optical method of characterizing deformation has been successfully demonstrated. For the tests of this method, the balloon catheter deforms 32 out of the 54 surface markers by more than 3 mm. Different deformation errors result from the different similarity metrics. The most accurate deformation predictions had an error of 75%. Conclusions: The results presented here demonstrate the utility of the phantom for objectively verifying deformation algorithms and determining which is the most accurate. They also indicate that the phantom would benefit from more electron density heterogeneity. The reduction of the deformable anatomy to a two-dimensional system allows for the use of nonradiopaque markers, which do not influence deformation algorithms. This is the fundamental advantage of this

Development of a QA Phantom for online image registration and resultant couch shifts

International Nuclear Information System (INIS)

Arumugam, S.; Jameson, M.G.; Holloway, L.C.

2010-01-01

Full text: Purpose Recently our centre purchased an Elekta-Synergy accelerator with kV-CBCT and a hexapod couch attachment. This system allows six degrees of freedom for couch lOp shifts, based on registration of on line imaging. We designed and built a phantom in our centre to test the accuracy and precision of this system. The goal of this project was to investigate the accuracy and practical utilisation of this phantom. Method The phantom was constructed from perspex sheets and high density dental putty (Fig. I). Five high density regions (three small regions to simulate prostate seeds and two larger regions to simulate boney anatomy) were incorporated to test the manual and automatic registrations within the software. The phantom was utilised to test the accuracy and precision of repositioning with the hexapod couch and imaging system. To achieve this, the phantom was placed on the couch at known orientations and the shifts were quantified using the registration of verification and reference image data sets. True shifts and those predicted by the software were compared. Results The geometrical accuracy of the phantom was verified with measurements of the CT scan to be with I mm of the intended geometry. The image registration and resultant couch shifts were found to be accurate within I mm and 0.5 degrees. The phantom was found to be practical and easy to use. Conclusion The presented phantom provides a less expensive and effective alternative to commercially available systems for verifying imaging registration and corresponding six degrees of freedom couch shifts. (author)

Evaluation of accuracy in target positions of multmodality imaging using brain phantom

Energy Technology Data Exchange (ETDEWEB)

Juh, R. H.; Suh, T. S.; Chung, Y. A. [The Catholic University of Korea, Seoul (Korea, Republic of)

2002-07-01

Determination of target positions in radiation therapy or radiosurgery is critical to the successful treatment. It is often difficult to recognize the target position only from single image modality since each image modality has unique image pattern and image distortion problem. The purpose of this study is to evaluate the accuracy of target positions with multimodality brain phantom. We obtained CT, MR, and SPECT scan images with the specially designed brain phantom. Brain phantom consists of brain for images and frame for localization. The phantom was a water fillable cylinder containing 58 axial layers of 2.0 mm thickness. Each layer allows water to permeate various regions to match gray matter to white matter of 1:1 ratio. Localization frame with 5mm inner diameter and 150/160 mm length were attached to the outside of the brain slice and inside of the phantom cylinder. The phantom was filled with 0.16 M CuSO{sub 4} solution for MRI scan, and distilled water for CT and 15mCi (555 MBq) Tc-99m for SPECT. Axial slice images and volume images including the targets and localizer were obtained for each modality. To evaluate the errors in target positions, the position of localization and target balls measured in SPECT were compared with MR and CT. Transformation parameters for translation, rotation and scaling were determined by surface matching each SPECT with MR and CT images. Multimodality phantom was very useful to evaluate the accuracy of target positions among the different types of image modality such as CT, MR and SPECT.

Improvement of skeleton conversion in ICRP reference phantom conversion project

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of); Kim, Seong Hoon [Dept. of Radiation Oncology, College of Medicine, Hanyang University, Seoul (Korea, Republic of)

2014-11-15

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future.

Improvement of skeleton conversion in ICRP reference phantom conversion project

International Nuclear Information System (INIS)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong; Kim, Seong Hoon

2014-01-01

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future

SU-E-T-792: Validation of a Secondary TPS for IROC-H Recalculation of Anthropomorphic Phantoms

Energy Technology Data Exchange (ETDEWEB)

Kerns, J; Howell, R; Followill, D; Melancon, A; Stingo, F; Kry, S [UT MD Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: To validate a secondary treatment planning system (sTPS) for use by the Imaging & Radiation Oncology Core-Houston (IROC-H). The TPS will recalculate phantom irradiations submitted by institutions to IROC-H and compare plan results of the institution to the sTPS. Methods: In-field dosimetric data was collected by IROC-H for numerous linacs at 6, 10, 15, and 18 MV. The data was aggregated and used to define reference linac classes; each class was then modeled in the sTPS (Mobius3D) by matching the in-field characteristics. Fields used to collect IROC-H data were recreated and recalculated using Mobius3D. The same dosimetric points were measured in the recalculation and compared to the initial collection data. Additionally, a 6MV Monte Carlo beam configuration was used to compare penumbrae in the Mobius3D models. Finally, a handful of IROC-H head and neck phantoms were recalculated using Mobius3D. Results: Recalculation and quantification of differences between reference data and Mobius3D values resulted in a relative matching score of 12.45 (0 is a perfect match) for the default 6MV Mobius3D beam configuration. By adjusting beam configuration options, iterations resulted in scores of 8.45, 6.32, and 3.52, showing that customization could have a dramatic effect on beam configuration. After in-field optimization, penumbra was compared between Monte Carlo and Mobius3D for the reference fields. For open jaw fields, FWHM field widths and penumbra widths were different by <0.6 and <1mm respectively; for MLC open fields the penumbra widths were up to 1.5mm different. Phantom recalculations showed good agreement, having an average of 0.6% error per beam. Conclusion: A secondary TPS has been validated for simple irradiation geometries using reference data collected by IROC-H. The beam was customized to the reference data iteratively and resulted in a good match. This system can provide independent recalculation of phantom plans based on independent reference data.

Possible association between phantom vibration syndrome and occupational burnout

Directory of Open Access Journals (Sweden)

Chen CP

2014-12-01

Full Text Available Chao-Pen Chen,1 Chi-Cheng Wu,2 Li-Ren Chang,3 Yu-Hsuan Lin4 1Department of Education, National Taiwan University Hospital, 2Department of Family Medicine, Min-Sheng General Hospital, Taoyuan City, 3Department of Psychiatry, National Taiwan University, College of Medicine, 4Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan Background: Phantom vibration syndrome (PVS and phantom ringing syndrome (PRS occur in many cell phone users. Previous studies have indicated an association between PVS/PRS and job stress. The aim of this study was to determine if PVS/PRS were also associated with occupational burnout.Methods: This was a cross-sectional study of 384 employees of a high-tech company in northern Taiwan. They all completed a phantom vibration and ringing questionnaire, the Hospital Anxiety and Depression Scale, and the Chinese version of the Occupational Burnout Inventory.Results: Significantly more women and people with at least a college education were in the population with PRS and PVS, respectively. Anxiety and depression had no associations with PVS/PRS. Higher scores for personal fatigue, job fatigue, and service target fatigue had an independent impact on the presence of PVS, but only a higher score for service target fatigue had an independent impact on the presence of PRS.Conclusion: The independent association between work-related burnout and PVS/PRS suggests that PVS/PRS may be a harbinger of mental stress or a component of the clinical burnout syndrome, and may even be a more convenient and accurate predictor of occupational burnout. Keywords: phantom vibration syndrome, phantom ringing syndrome, occupational burnout

Dosimetry using radiochromic film and planning algorithms in heterogeneous phantoms

International Nuclear Information System (INIS)

Leite, Vinicius Freitas

2012-01-01

This work analyzes, through the study of the interaction of electromagnetic radiation with matter, two schemes of heterogeneous phantoms schematised to simulate real cases of planning with different electronic densities through the Pencil Beam, Collapsed Cone and Analytical Anisotropic Algorithm algorithms and compare with measurements Of relative absorbed dose in an IBA CC13 ionization chamber and Gafchromic® EBT2 radiochromic film. Epichlorohydrin rubber and its compatibility in comparison with human bone has also been evaluated. The assembly of the heterogeneous phantoms was feasible and the results regarding the density and attenuation of the rubber presented consistent values. However, the study of PDPs in constructed phantoms showed a considerable percentage discrepancy between measurements and planning

Dosimetry in a torso phantom during a mammography

International Nuclear Information System (INIS)

Hernandez O, M.; Duran M, H. A.; Pinedo S, A.; Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R.; Rivera M, T.; Ventura M, J.

2009-10-01

Two dosimetric magnitudes, the absorbed dose and the kerma in air to the entrance of torso have been determined. These dosimetric magnitudes are due to the radiation that is dispersed in the mammary gland when the patient undergoes a mammography study. The kerma to the entrance of the torso and the absorbed dose by the torso was obtained in a phantom of paraffin and with thermoluminescent dosemeters of ZrO 2 . The dosemeters were placed on the surface of the torso phantom while the mammography was carried out. (author)

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

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.

A feasiblity study of an ultrasonic test phantom arm

Science.gov (United States)

Schneider, Philip

This thesis is a feasibility study for the creation of a test phantom that replicates the physiological features, from an acoustic and mechanical standpoint, of that of a human arm. Physiological feature set includes; Heart, Arteries, Veins, Bone, Muscle, Fat, Skin, and Dermotographic Features (finger prints). Mechanical Aspects include, vascular compression and distention, elasticity of tissue layers, mechanics of human heart. The end goal of which to have a working understanding of each component in order to create a controllable, real time, physiologically accurate, test phantom for a wide range of ultrasonic based applications. These applications can range from devices like wearable technologies to medical training, to biometric "Liveness" detection methods. The proposed phantom would allow for a number of natural bodily functions to be measured including but not limited to vascular mapping, blood pressure, heart rate, subdermal imaging, and general ultrasonic imaging.

Radiation protection to the eye and thyroid during diagnostic cerebral angiography: a phantom study.

LENUS (Irish Health Repository)

Shortt, C P

2008-08-01

We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

Radiation protection to the eye and thyroid during diagnostic cerebral angiography : a phantom study

International Nuclear Information System (INIS)

Shortt, C. P.; Malone, L.; Thornton, J.; Brennan, P.; Lee, M. J.

2008-01-01

Full text: We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

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.

Estimation of internal dose from radiocesium and phantom

International Nuclear Information System (INIS)

Uchiyama, Masafumi; Nakamura, Yuji

1994-01-01

A complicated model describing the movement of a radionuclide in both the natural environment and socioeconomical systems is usually used to estimate the internal dose to the public in terms of collective dose, taking demographic data into account. The result can be certified for reliability in some compartments of the model. One of the compartments is the body content. In the case of radiocesium, the individual body burden can be measured using a whole-body counter. The measurement must be calibrated with a phantom. The public is composed of individuals of various ages. Accordingly, the whole-body counter should be calibrated with a set of phantoms approximating individuals of different body sizes. Relationships between counting efficiency and body size were analyzed on 137 Cs 134 Cs or 40 K incorporated into the whole-body using a set of phantoms. Four sizes covering average Japanese physiques from infant to adult male, were chosen to prepare an anthropomorphic phantom system. The distribution of 137 Cs in aquatic solution was homogeneous through the phantom. A whole-body counter at the National Institute of Radiological Sciences, was used at a rate of 5 cm per minute in a scanning mode. The measurements were carried out in an iron room. Relations were analyzed between counting efficiency and some anthropometric parameters. The best fit was given by a linear equation of both reciprocals of height in cm and weight in kg, with a correlation coefficient of 1.00 for 137 Cs. The result indicates that radioactivity of 137 Cs can be determined for individuals with different anthropometric parameters using the whole-body counter system. This means that effective equivalent doses for individuals can be computed accurately from the measurements. Further, an estimate on the body content from an dose estimation model using measurements of radioactivity in environmental substances can be evaluated by comparing the body burden measured. (J.P.N.)

Effect of phantom dimension variation on Monte Carlo simulation speed and precision

International Nuclear Information System (INIS)

Lin Hui; Xu Yuanying; Xu Liangfeng; Li Guoli; Jiang Jia

2007-01-01

There is a correlation between Monte Carlo simulation speed and the phantom dimension. The effect of the phantom dimension on the Monte Carlo simulation speed and precision was studied based on a fast Monte Carlo code DPM. The results showed that when the thickness of the phantom was reduced, the efficiency would increase exponentially without compromise of its precision except for the position at the tailor. When the width of the phantom was reduced to outside the penumbra, the effect on the efficiency would be neglectable. However when it was reduced to within the penumbra, the efficiency would be increased at some extent without precision loss. This result was applied to a clinic head case, and the remarkable increased efficiency was acquired. (authors)

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.

Quality assessment of ultrasonographic equipment using an ATS-539 multipurpose phantom

International Nuclear Information System (INIS)

Kim, Pyo Nyun; Lim, Joo Won; Kim, Hyun Cheol; Yoon, Young Cheol; Sung, Deuk Je; Moon, Min Hoan; Kim, Jeong Sook; Kim, Jong Chan

2008-01-01

To determine the rate of congruence and to standardize assessment of US (ultrasound) phantom images with the use of an ATS-539 multipurpose phantom for US equipment currently utilized in Korea. US phantom images were scanned with a 3.0-5.0 MHz convex transducer and were digitized by use of an analogue-digital converter. Members of a committee with consent evaluated the US phantom images from 108 types of ultrasound equipment. The dead zone, vertical and horizontal measurement, axial/lateral resolution, focal zone, sensitivity, functional resolution and gray scale/dynamic range were evaluated. Congruence or incongruence of ultrasound equipment was determined based on the results of dead zone, axial/lateral resolution and gray scale/dynamic range measurements. Other factors were evaluated for the possibility as criteria with the use of the Mann-Whitney U test and receiver operator characteristic (ROC) curve analysis. The dead zone, axial/lateral resolution and gray scale/dynamic range were 91.7%, 94.4% and 76.9%, respectively, for suitable US equipment. Considering all three factors, 78 types of ultrasound equipment were passed. The congruence rate of focal zone and functional resolution were 62.4% and 69.3% of the US equipment, respectively. Of the US equipment, 72.2% of the equipment was acceptable based on the dead zone, axial/lateral resolution, and gray scale/dynamic range measurement as determined with the use of an ATS-539 phantom. Focal zone and 8 mm-functional resolution can be useful as a standard in the assessment of a US phantom image

Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom

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Batista Nogueira, Luciana [Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Lemos Silva, Hugo Leonardo [Santa Casa Hospital, Belo Horizonte (Brazil); Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil)

2015-07-01

This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic films EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm{sup 2} each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the

Development of the new phantom for evaluation of SPECT performance

International Nuclear Information System (INIS)

Fukukita, H.; Oyamada, H.; Nagaiwa, K.; Kawai, H.; Terui, S.

1984-01-01

The authors developed a new Phantom designed to evaluate the SPECT system performances of rotational gamma cameras. This phantom is composed of 5 parts, and each of them has its own purpose; such as measurements of 1) spatial resolution 2) slice thickness, 3) dose linearity, 4) uniformity, and 5) image distortion. These parts are made of Acrylic (0.8 cm in thickness) and each of them has the same disc-shape, measuring 28.4 cm in inner diameter and 7 cm in inner length. For the large field of view cameras, it is possible to set up-to 4 parts together if necessary. Therefore, 4 different parameters can be obtained at one rotation. The phantom was filled with Tc-99m solution, and SPET data were obtained as follows: for the determination of spatial resolution and slice thickness, 128 linear sampling with every 5 0 angular rotation was performed, and 64 linear sampling with every 10 0 angular rotation for dose linearity uniformity, and image distortion. The values obtained with the phantom were FWHM of 19.1 mm for spatial resolution, FWHM of 19.9 mm for slice thickness, and integral uniformity of 36.4%. For dose linearity a good correlating (r=0.99) was obtained. For image distortion it was easy to detect the misalignment of the electrical and mechanical axes. The authors found that this phantom was a suitable tool as a routine quality control and daily maintenance of SPECT system

Construction tool and suitability of voxel phantom for skin dosimetry

International Nuclear Information System (INIS)

Antunes, Paula C.G.; Siqueira, Paulo T.D.; Fonseca, Gabriel P.; Yoriyaz, Helio

2011-01-01

This paper describes a new software tool called 'SkinVop' which was developed to enable accurate voxel phantom skin dosimetry. A voxel phantom is a model used to describe human anatomy in a realistic way in radiation transport codes. This model is a three-dimensional representation of the human body in the form of an array of identification numbers that are arranged in a 3D matrix. Each entry in this array represents a voxel (volume element) directly associated to the units of picture resolution (pixel) of medical images. Currently, these voxel phantoms, in association with the transport code MCNP (Monte Carlo N-Particle), have provided subsidies to the planning systems used on the hospital routine, once they afford accurate and personalized estimative of dose distribution. However, these assessments are limited to geometric representations of organs and tissues in the voxel phantom, which do not discriminates some thin body structure, such as the skin. In this context, to enable accurate dosimetric skin dose assessment by the MCNP code, it was developed this new software tool that discriminates this region with thickness and localization in the voxel phantoms similar to the real. This methodology consists in manipulating the skin volume elements by segmenting and subdividing them in different thicknesses. A graphical user interface was designed to fulfill display the modified voxel model. This methodology is extremely useful once the skin dose is inaccurately assessed of current hospital system planning, justified justly by its small thickness. (author)

Construction tool and suitability of voxel phantom for skin dosimetry

Energy Technology Data Exchange (ETDEWEB)

Antunes, Paula C.G.; Siqueira, Paulo T.D.; Fonseca, Gabriel P.; Yoriyaz, Helio, E-mail: ptsiquei@ipen.b, E-mail: hyoriyaz@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

This paper describes a new software tool called 'SkinVop' which was developed to enable accurate voxel phantom skin dosimetry. A voxel phantom is a model used to describe human anatomy in a realistic way in radiation transport codes. This model is a three-dimensional representation of the human body in the form of an array of identification numbers that are arranged in a 3D matrix. Each entry in this array represents a voxel (volume element) directly associated to the units of picture resolution (pixel) of medical images. Currently, these voxel phantoms, in association with the transport code MCNP (Monte Carlo N-Particle), have provided subsidies to the planning systems used on the hospital routine, once they afford accurate and personalized estimative of dose distribution. However, these assessments are limited to geometric representations of organs and tissues in the voxel phantom, which do not discriminates some thin body structure, such as the skin. In this context, to enable accurate dosimetric skin dose assessment by the MCNP code, it was developed this new software tool that discriminates this region with thickness and localization in the voxel phantoms similar to the real. This methodology consists in manipulating the skin volume elements by segmenting and subdividing them in different thicknesses. A graphical user interface was designed to fulfill display the modified voxel model. This methodology is extremely useful once the skin dose is inaccurately assessed of current hospital system planning, justified justly by its small thickness. (author)

A MCNP-based calibration method and a voxel phantom for in vivo monitoring of 241Am in skull

International Nuclear Information System (INIS)

Moraleda, M.; Gomez-Ros, J.M.; Lopez, M.A.; Navarro, T.; Navarro, J.F.

2004-01-01

Whole body counter (WBC) facilities are currently used for assessment of internal radionuclide body burdens by directly measuring the radiation emitted from the body. Previous calibration of the detection devices requires the use of specific anthropomorphic phantoms. This paper describes the MCNP-based Monte Carlo technique developed for calibration of the germanium detectors (Canberra LE Ge) used in the CIEMAT WBC for in vivo measurements of 241 Am in skull. The proposed method can also be applied for in vivo counting of different radionuclides distributed in other anatomical regions as well as for other detectors. A computer software was developed to automatically generate the input files for the MCNP code starting from any segmented human anatomy data. A specific model of a human head for the assessment of 241 Am was built based on the tomographic phantom VOXELMAN of Yale University. The germanium detectors were carefully modelled from data provided by the manufacturer. This numerical technique has been applied to investigate the best counting geometry and the uncertainty due to improper positioning of the detectors

Phantom-like behavior of a DGP-inspired Scalar-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Nozari, Kourosh; Azizi, Tahereh; Setare, M.R.

2009-01-01

We study the phantom-like behavior of a DGP-inspired braneworld scenario where curvature correction on the brane is taken into account. We include a possible modification of the induced gravity on the brane by incorporating higher order curvature terms of Gauss-Bonnet type. We investigate the cosmological implications of the model and we show that the normal branch of the scenario self-accelerates in this modified scenario without introducing any dark energy component. Also, a phantom-like behavior can be realized in this model without introducing any phantom field that suffers from serious difficulties such as violation of the null energy condition

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.

Specific developed phantoms and software to assess radiological equipment image quality

International Nuclear Information System (INIS)

Verdu, G.; Rodenas, F.

2011-01-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

Specific developed phantoms and software to assess radiological equipment image quality

Energy Technology Data Exchange (ETDEWEB)

Verdu, G., E-mail: gverdu@iqn.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Ingenieria Quimica y Nuclear; Mayo, P., E-mail: p.mayo@titaniast.com [TITANIA Servicios Teconologicos, Valencia (Spain); Rodenas, F., E-mail: frodenas@mat.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Matematica Aplicada; Campayo, J.M., E-mail: j.campayo@lainsa.com [Logistica y Acondicionamientos Industriales S.A.U (LAINSA), Valencia (Spain)

2011-07-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

Development and liver of phantom anthropomorphic application for use in radiology

International Nuclear Information System (INIS)

Melo, M.G.; Silva, L.F.; Ferreira, F. C.L.; Cunha, C.J.; Paschoal, C.M.M.

2015-01-01

The use of artificial ionizing radiation has also been employed in several areas, namely: medicine, agriculture, industry, ink curing etc. However, the use of radiation for medical purposes of diagnosis or therapy is being treated with more attention due to its increased use and the use of simulators object for quality control and training of professionals. The phantoms and are used to aid radiographic procedures, they may simulate a part of the body, both in its form as mass, density, and attenuation. The objective of this work was the development and application of liver anthropomorphic phantom for use in diagnostic radiology and training professionals. The construction of the liver anthropomorphic phantom was through literature and it was noticed that the use of phantoms are relatively low. For the construction of the mold of the phantom was used an adult human liver with early cirrhosis that was preserved in formalin for teaching demonstrations in Prof. Human Anatomy Museum collection Osvaldo Cruz of milk from the Federal University of Sergipe. With this work, we emphasize the need for the control program and quality assurance in radiology doctor to ensure image quality and low exposure of patients and professionals, since the radiological examinations are extremely important, because its contribution decisively in medical diagnosis. (authors)

[Development of a digital chest phantom for studies on energy subtraction techniques].

Science.gov (United States)

Hayashi, Norio; Taniguchi, Anna; Noto, Kimiya; Shimosegawa, Masayuki; Ogura, Toshihiro; Doi, Kunio

2014-03-01

Digital chest phantoms continue to play a significant role in optimizing imaging parameters for chest X-ray examinations. The purpose of this study was to develop a digital chest phantom for studies on energy subtraction techniques under ideal conditions without image noise. Computed tomography (CT) images from the LIDC (Lung Image Database Consortium) were employed to develop a digital chest phantom. The method consisted of the following four steps: 1) segmentation of the lung and bone regions on CT images; 2) creation of simulated nodules; 3) transformation to attenuation coefficient maps from the segmented images; and 4) projection from attenuation coefficient maps. To evaluate the usefulness of digital chest phantoms, we determined the contrast of the simulated nodules in projection images of the digital chest phantom using high and low X-ray energies, soft tissue images obtained by energy subtraction, and "gold standard" images of the soft tissues. Using our method, the lung and bone regions were segmented on the original CT images. The contrast of simulated nodules in soft tissue images obtained by energy subtraction closely matched that obtained using the gold standard images. We thus conclude that it is possible to carry out simulation studies based on energy subtraction techniques using the created digital chest phantoms. Our method is potentially useful for performing simulation studies for optimizing the imaging parameters in chest X-ray examinations.

Averaged head phantoms from magnetic resonance images of Korean children and young adults

Science.gov (United States)

Han, Miran; Lee, Ae-Kyoung; Choi, Hyung-Do; Jung, Yong Wook; Park, Jin Seo

2018-02-01

Increased use of mobile phones raises concerns about the health risks of electromagnetic radiation. Phantom heads are routinely used for radiofrequency dosimetry simulations, and the purpose of this study was to construct averaged phantom heads for children and young adults. Using magnetic resonance images (MRI), sectioned cadaver images, and a hybrid approach, we initially built template phantoms representing 6-, 9-, 12-, 15-year-old children and young adults. Our subsequent approach revised the template phantoms using 29 averaged items that were identified by averaging the MRI data from 500 children and young adults. In females, the brain size and cranium thickness peaked in the early teens and then decreased. This is contrary to what was observed in males, where brain size and cranium thicknesses either plateaued or grew continuously. The overall shape of brains was spherical in children and became ellipsoidal by adulthood. In this study, we devised a method to build averaged phantom heads by constructing surface and voxel models. The surface model could be used for phantom manipulation, whereas the voxel model could be used for compliance test of specific absorption rate (SAR) for users of mobile phones or other electronic devices.

Investigation of partial volume effect in different PET/CT systems: a comparison of results using the madeira phantom and the NEMA NU-2 2001 phantom

International Nuclear Information System (INIS)

Chipiga, L.; Sydoff, M.; Zvonova, I.; Bernhardsson, C.

2016-01-01

Positron emission tomography combined with computed tomography (PET/CT) is a quantitative technique used for diagnosing various diseases and for monitoring treatment response for different types of tumours. However, the accuracy of the data is limited by the spatial resolution of the system. In addition, the so-called partial volume effect (PVE) causes a blurring of image structures, which in turn may cause an underestimation of activity of a structure with high-activity content. In this study, a new phantom, MADEIRA (Minimising Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations) for activity quantification in PET and single photon emission computed tomography (SPECT) was used to investigate the influence on the PVE by lesion size and tumour-to-background activity concentration ratio (TBR) in four different PET/CT systems. These measurements were compared with data from measurements with the NEMA NU-2 2001 phantom. The results with the MADEIRA phantom showed that the activity concentration (AC) values were closest to the true values at low ratios of TBR (<10) and reduced to 50 % of the actual AC values at high TBR (30-35). For all scanners, recovery of true values became closer to 1 with an increasing diameter of the lesion. The MADEIRA phantom showed good agreement with the results obtained from measurements with the NEMA NU-2 2001 phantom but allows for a wider range of possibilities in measuring image quality parameters. (authors)

Customized three-dimensional printed optical phantoms with user defined absorption and scattering

Science.gov (United States)

Pannem, Sanjana; Sweer, Jordan; Diep, Phuong; Lo, Justine; Snyder, Michael; Stueber, Gabriella; Zhao, Yanyu; Tabassum, Syeda; Istfan, Raeef; Wu, Junjie; Erramilli, Shyamsunder; Roblyer, Darren M.

2016-03-01

The use of reliable tissue-simulating phantoms spans multiple applications in spectroscopic imaging including device calibration and testing of new imaging procedures. Three-dimensional (3D) printing allows for the possibility of optical phantoms with arbitrary geometries and spatially varying optical properties. We recently demonstrated the ability to 3D print tissue-simulating phantoms with customized absorption (μa) and reduced scattering (μs`) by incorporating nigrosin, an absorbing dye, and titanium dioxide (TiO2), a scattering agent, to acrylonitrile butadiene styrene (ABS) during filament extrusion. A physiologically relevant range of μa and μs` was demonstrated with high repeatability. We expand our prior work here by evaluating the effect of two important 3D-printing parameters, percent infill and layer height, on both μa and μs`. 2 cm3 cubes were printed with percent infill ranging from 10% to 100% and layer height ranging from 0.15 to 0.40 mm. The range in μa and μs` was 27.3% and 19.5% respectively for different percent infills at 471 nm. For varying layer height, the range in μa and μs` was 27.8% and 15.4% respectively at 471 nm. These results indicate that percent infill and layer height substantially alter optical properties and should be carefully controlled during phantom fabrication. Through the use of inexpensive hobby-level printers, the fabrication of optical phantoms may advance the complexity and availability of fully customizable phantoms over multiple spatial scales. This technique exhibits a wider range of adaptability than other common methods of fabricating optical phantoms and may lead to improved instrument characterization and calibration.

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

NOTE: On the need to revise the arm structure in stylized anthropomorphic phantoms in lateral photon irradiation geometry

Science.gov (United States)

Lee, Choonsik; Lee, Choonik; Lee, Jai-Ki

2006-11-01

Distributions of radiation absorbed dose within human anatomy have been estimated through Monte Carlo radiation transport techniques implemented for two different classes of computational anthropomorphic phantoms: (1) mathematical equation-based stylized phantoms and (2) tomographic image-based voxel phantoms. Voxel phantoms constructed from tomographic images of real human anatomy have been actively developed since the late 1980s to overcome the anatomical approximations necessary with stylized phantoms, which themselves have been utilized since the mid 1960s. However, revisions of stylized phantoms have also been pursued in parallel to the development of voxel phantoms since voxel phantoms (1) are initially restricted to the individual-specific anatomy of the person originally imaged, (2) must be restructured on an organ-by-organ basis to conform to reference individual anatomy and (3) cannot easily represent very fine anatomical structures and tissue layers that are thinner than the voxel dimensions of the overall phantom. Although efforts have been made to improve the anatomic realism of stylized phantoms, most of these efforts have been limited to attempts to alter internal organ structures. Aside from the internal organs, the exterior shapes, and especially the arm structures, of stylized phantoms are also far from realistic descriptions of human anatomy, and may cause dosimetry errors in the calculation of organ-absorbed doses for external irradiation scenarios. The present study was intended to highlight the need to revise the existing arm structure within stylized phantoms by comparing organ doses of stylized adult phantoms with those from three adult voxel phantoms in the lateral photon irradiation geometry. The representative stylized phantom, the adult phantom of the Oak Ridge National Laboratory (ORNL) series and two adult male voxel phantoms, KTMAN-2 and VOXTISS8, were employed for Monte Carlo dose calculation, and data from another voxel phantom, VIP

Design of a digital phantom population for myocardial perfusion SPECT imaging research

International Nuclear Information System (INIS)

Ghaly, Michael; Du, Yong; Fung, George S K; Tsui, Benjamin M W; Frey, Eric; Links, Jonathan M

2014-01-01

Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48–184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as

Use of VAP3D software in the construction of pathological anthropomorphic phantoms for dosimetric evaluations

International Nuclear Information System (INIS)

Lima, Lindeval Fernandes de; Lima, Fernando R.A.

2011-01-01

This paper performs a new type of dosimetric evaluation, where it was used a phantom of pathological voxels (representative phantom of sick person). The software VAP3D (Visualization and Analysis of Phantoms 3D) were used for, from a healthy phantom (phantom representative of healthy person), to introduce three dimensional regions to simulate tumors. It was used the Monte Carlo ESGnrc code to simulate the X ray photon transport, his interaction with matter and evaluation of absorbed dose in organs and tissues from thorax region of the healthy phantom and his pathological version. This is a computer model of typical exposure for programming the treatments in radiodiagnostic

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

A Dynamic Compliance Cervix Phantom Robot for Latent Labor Simulation.

Science.gov (United States)

Luk, Michelle Jennifer; Lobb, Derek; Smith, James Andrew

2018-05-09

Physical simulation systems are commonly used in training of midwifery and obstetrics students, but none of these systems offers a dynamic compliance aspect that would make them more truly representative of cervix ripening. In this study, we introduce a unique soft robot phantom that simulates the cervix softening during the latent labor phase of birth. This proof-of-concept robotic phantom can be dilated by 1 cm and effaced by 35% through the application of a Foley catheter-like loading mechanism. Furthermore, psychophysics trials demonstrate how untrained subjects can identify hard and soft states of the phantom with specificities of 91% and 87%, respectively. Both results indicated the appropriateness for application of this soft robot technology to birth training simulators.

Resource allocation for phantom cellular networks: Energy efficiency vs spectral efficiency

KAUST Repository

Abdelhady, Amr Mohamed Abdelaziz; Amin, Osama; Alouini, Mohamed-Slim

2016-01-01

Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Mean-while, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for the recently proposed two-tier network architecture known as phantom cellular networks. The optimization framework includes both EE and SE, where we propose an algorithm that finds the SE and EE resource allocation strategies for phantom cellular networks. Then, we compare the performance of both design strategies versus the number of users, and phantom cells share of the total number of available resource blocks. We aim to investigate the effect of some system parameters to achieve improved SE performance at a non-significant loss in EE performance, or vice versa. It was found that increasing phantom cells share of resource blocks decreases the SE performance loss due to EE optimization when compared with the optimized SE performance. © 2016 IEEE.

Resource allocation for phantom cellular networks: Energy efficiency vs spectral efficiency

KAUST Repository

Abdelhady, Amr M.

2016-07-26

Multi-tier heterogeneous networks have become an essential constituent for next generation cellular networks. Mean-while, energy efficiency (EE) has been considered a critical design criterion along with the traditional spectral efficiency (SE) metric. In this context, we study power and spectrum allocation for the recently proposed two-tier network architecture known as phantom cellular networks. The optimization framework includes both EE and SE, where we propose an algorithm that finds the SE and EE resource allocation strategies for phantom cellular networks. Then, we compare the performance of both design strategies versus the number of users, and phantom cells share of the total number of available resource blocks. We aim to investigate the effect of some system parameters to achieve improved SE performance at a non-significant loss in EE performance, or vice versa. It was found that increasing phantom cells share of resource blocks decreases the SE performance loss due to EE optimization when compared with the optimized SE performance. © 2016 IEEE.

Validation of PIMAL 3.0-phantom with moving arms and legs

International Nuclear Information System (INIS)

Griffin, Keith T.; Bellamy, Michael B.

2017-01-01

When it comes to determining radiation protection measurements, complex geometries often require the use of computational modeling to solve the problems; the human body is no exception. However, both old and new phantom models have almost always been rigidly created in the vertical upright position. Oak Ridge National Laboratory solved this issue in 2007 by developing a piece of software named 'Phantom with Moving Arms and Legs (PIMAL)', which creates a flexible phantom model for computer simulations. Though the initial hermaphrodite phantom is validated, new gender-specific models need validation against generally accepted values. Thus, the purpose of this study was to compare the dose coefficients from PIMAL against known values in Federal Guidance Report 12 for water submersion. Of 21 organ-tissue doses, all but 2 matched to within 15% for photon energies above 1 MeV. For plots with notable discrepancies at multiple energies, including bone surface and effective dose, explanations are given to justify differences. (authors)

Scatter correction method for x-ray CT using primary modulation: Phantom studies

International Nuclear Information System (INIS)

Gao Hewei; Fahrig, Rebecca; Bennett, N. Robert; Sun Mingshan; Star-Lack, Josh; Zhu Lei

2010-01-01

Purpose: Scatter correction is a major challenge in x-ray imaging using large area detectors. Recently, the authors proposed a promising scatter correction method for x-ray computed tomography (CT) using primary modulation. Proof of concept was previously illustrated by Monte Carlo simulations and physical experiments on a small phantom with a simple geometry. In this work, the authors provide a quantitative evaluation of the primary modulation technique and demonstrate its performance in applications where scatter correction is more challenging. Methods: The authors first analyze the potential errors of the estimated scatter in the primary modulation method. On two tabletop CT systems, the method is investigated using three phantoms: A Catphan(c)600 phantom, an anthropomorphic chest phantom, and the Catphan(c)600 phantom with two annuli. Two different primary modulators are also designed to show the impact of the modulator parameters on the scatter correction efficiency. The first is an aluminum modulator with a weak modulation and a low modulation frequency, and the second is a copper modulator with a strong modulation and a high modulation frequency. Results: On the Catphan(c)600 phantom in the first study, the method reduces the error of the CT number in the selected regions of interest (ROIs) from 371.4 to 21.9 Hounsfield units (HU); the contrast to noise ratio also increases from 10.9 to 19.2. On the anthropomorphic chest phantom in the second study, which represents a more difficult case due to the high scatter signals and object heterogeneity, the method reduces the error of the CT number from 327 to 19 HU in the selected ROIs and from 31.4% to 5.7% on the overall average. The third study is to investigate the impact of object size on the efficiency of our method. The scatter-to-primary ratio estimation error on the Catphan(c)600 phantom without any annulus (20 cm in diameter) is at the level of 0.04, it rises to 0.07 and 0.1 on the phantom with an

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

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

Fabrication of a set of realistic torso phantoms for calibration of transuranic nuclide lung counting facilities

International Nuclear Information System (INIS)

Griffith, R.V.; Anderson, A.L.; Sundbeck, C.W.; Alderson, S.W.

1983-01-01

A set of 16 tissue equivalent torso phantoms has been fabricated for use by major laboratories involved in counting transuranic nuclides in the lung. These phantoms, which have bone equivalent plastic rib cages, duplicate the performance of the DOE Realistic Phantom set. The new phantoms (and their successors) provide the user laboratories with a highly realistic calibration tool. Moreover, use of these phantoms will allow participating laboratories to intercompare calibration information, both on formal and informal bases. 3 refs., 2 figs

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

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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.

Optimization for PET imaging based on phantom study and NECdensity

International Nuclear Information System (INIS)

Daisaki, Hiromitsu; Shimada, Naoki; Shinohara, Hiroyuki

2012-01-01

In consideration of the requirement for global standardization and quality control of PET imaging, the present studies gave an outline of phantom study to decide both scan and reconstruction parameters based on FDG-PET/CT procedure guideline in Japan, and optimization of scan duration based on NEC density was performed continuously. In the phantom study, scan and reconstruction parameters were decided by visual assessment and physical indexes (N 10mm , NEC phantom , Q H,10mm /N 10mm ) to visualize hot spot of 10 mm diameter with standardized uptake value (SUV)=4 explicitly. Simultaneously, Recovery Coefficient (RC) was evaluated to recognize that PET images had enough quantifiably. Scan durations were optimized by Body Mass Index (BMI) based on retrospective analysis of NEC density . Correlation between visual score in clinical FDG-PET images and NEC density fell after the optimization of scan duration. Both Inter-institution and inter-patient variability were decreased by performing the phantom study based on the procedure guideline and the optimization of scan duration based on NEC density which seem finally useful to practice highly precise examination and promote high-quality controlled study. (author)

SU-E-J-07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes

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Morris, B; Duggar, W; Stanford, J; Yang, C [University of Mississippi Med. Center, Jackson, MS (United States)

2015-06-15

Purpose: IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI-preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced. Methods: 32 and 16cm CTDI-phantoms were used as surrogates for adult and child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta’s Chest-preset to establish a dose baseline. The child-phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN-preset (named Peds Abd-pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child-phantom (relative to the baseline), while providing clinically-usable image quality. Results: The baseline dose to the child-phantom from the Chest-preset was 310% that of the adult-phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest-preset to the HN-preset, while the Peds Abd-pelvis-preset similarly reduced the dose by an average of 92%. Conclusion: XVI-preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically-usable image quality. Using a modified imaging preset (Peds Abd-pelvis-preset) greatly reduced the dose to the child-phantom compared to the dose for the Chest-preset for both the child and adult-phantoms. This outcome provides support for the development of child-specific protocols for IGRT imaging in pediatric patients.

SU-E-J-07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes

International Nuclear Information System (INIS)

Morris, B; Duggar, W; Stanford, J; Yang, C

2015-01-01

Purpose: IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI-preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced. Methods: 32 and 16cm CTDI-phantoms were used as surrogates for adult and child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta’s Chest-preset to establish a dose baseline. The child-phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN-preset (named Peds Abd-pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child-phantom (relative to the baseline), while providing clinically-usable image quality. Results: The baseline dose to the child-phantom from the Chest-preset was 310% that of the adult-phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest-preset to the HN-preset, while the Peds Abd-pelvis-preset similarly reduced the dose by an average of 92%. Conclusion: XVI-preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically-usable image quality. Using a modified imaging preset (Peds Abd-pelvis-preset) greatly reduced the dose to the child-phantom compared to the dose for the Chest-preset for both the child and adult-phantoms. This outcome provides support for the development of child-specific protocols for IGRT imaging in pediatric patients

Phantom sensations in people with complete spinal cord lesions: a grounded theory perspective.

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Drysdale, Daren G; Shem, Kazuko; Walbom, Agnes; Miner, Maureen D; Maclachlan, Malcolm

2009-01-01

Phantom sensations are somatic phenomena arising from denervated parts of the body. There is very little research, and much diagnostic confusion, regarding such experiences in people with spinal cord injuries. In the case of 'complete' spinal cord lesions, phantom experiences may challenge, and indeed, contradict, the understanding that both clinicians and patients have of such injuries. This paper seeks to provide a better understanding of such 'phantom' sensations in spinal cord injury. We used grounded theory methods to explore 'phantom' sensations as experienced by individuals with complete (ASIA A) spinal lesions. Eight people with complete lesions, who were selected through theoretical sampling, participated in a semi-structured interview. Emergent themes included injury context, sensations experienced, the meaning of sensations, body connectivity, attitude and communication about sensations. Our results provide an enhanced understanding of the embodied experience of phantom sensations, and important insights regarding self-construction and rehabilitative processes in people with spinal cord injury who experience such anomalous sensations.

A phantom for assessing the personal dose equivalent, HP(10)

International Nuclear Information System (INIS)

Santoro, C.; Filho, J.A

2013-01-01

Characteristics of a phantom designed to evaluate the personal dose equivalent, H P (10), and appropriate for photographic dosimetry are presented. It is called HP(10) phantom due to cavities constructed to insert dosimetric films at a depth of 10 mm. The H P (10) phantom is irradiated with ionizing radiation energy, E, from 45 to 1250 keV, with doses ranging from 0.2 to 50 mSv. It is positioned in the direction α = 0 °, and the radiation field focusing perpendicular to its front surface. So, are established calibration curves of dosimeters in the position conventionally true and quantities H P (10). It made a comparison between the responses obtained with the H P (10) phantom and responses obtained when using the calibration procedure recommended by ISO dosimeters. The ISO recommends getting the air kerma, Ka, for photons at test point of the radiation field by an ionization chamber. And through conversion coefficients, h pK (10; E, α), becomes the air kerma for H P (10). The ISO 4037-3 recommendation has been studied by researchers to ensure that the low energy spectral differences occur in radiation fields which are generated by various X-ray equipment, and induce changes in the percentages of conversion coefficients on the order of 10% to 90% . On the basis of the recommendations ISO, this article develops phantom able to assess the dose to the influence of scattering and absorption of radiation, its implications with respect to dosimetry, providing improvement in the assessment of doses. (author)

Using NURBS type phantoms for the investigation of morphological factors affecting pulmonary anthropo-radiometry

International Nuclear Information System (INIS)

Farah, J.; Broggio, D.; Franck, D.

2010-01-01

As existing phantoms used for the calibration of dosimetry measurements, notably in anthropo-radiometry, exhibit a poor anatomic realism because of their crude geometries, compositions and densities, and some other drawbacks, the authors, within the frame of improvement of calibration techniques, report the combined use of Mesh and NURBS-type phantoms (Non Uniform Rational B-Splines) which allow smooth shapes and finer geometries to be replicated. More precisely, they report the application of this type of phantoms to the modelling of a thorax and of a ribcage. They describe the protocols used to generate these phantoms and how some variations are introduced to take morphological characteristics (for example a female thorax) as well as various gamma ray distributions into account. Results are discussed in terms of validation of phantoms, and morphology variation

Verification of a table of phantom scatter factors for radiotherapy treatment planning

International Nuclear Information System (INIS)

Arts, J.K.; Bailey, M.J.; Hill, R.

2004-01-01

Full text: Many commercially available treatment planning systems require the medical physicist to measure and enter significant quantities of data for the verification of physics based algorithms. The CMS XiO (St. Louis, USA) treatment planning system requires a table of phantom scatter factors amongst other data. In a previous paper by Storchi et al, a table of phantom scatter factors is described. This table gives the phantom scatter factor as a function of field size and quality index determined from a collection of measured data for the total scatter factor and the collimator scatter factor from 25 different beam qualities ranging from 4MV up to 25MV. These factors have been determined at a fixed reference depth of 10cm for square fields of various sizes. This work investigates the claim that this table can be used as an alternative to calculated phantom scatter curve from measured data of a particular treatment unit. According to definition, it is difficult to directly measure the phantom scatter correction factor (Sp). This problem can be solved using the relation; S cp (A) = S c (A)S p (A) where S cp (A)) is the measured total scatter factor for a field size of square side dimension, A and S c (A) is the measured collimator scatter factor for a field size of square side dimension, A (Khan et al 1980, van Gasteren et al 1991). The total scatter correction factor (Sc,p) was measured in a full phantom, and the collimator scatter factor (Sc) measured using an ESTRO mini-phantom. These factors were measured on three Siemens linear accelerators (Concord, USA) with energies 6MV and 18MV and square field sizes ranging from 4x4cm to 40x40cm. The Primus and KD Mevatron produced 6 and 18MV X-rays and the MXE Mevatron produced 6Mv X-rays only. The values for Sp were calculated by rearranging equation (1). Phantom scatter factors were calculated from the data provided by Storchi et al using the quality index of each beam. For comparison, a set of Sp values was

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

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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.)

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.

The collapsed cone algorithm for (192)Ir dosimetry using phantom-size adaptive multiple-scatter point kernels.

Science.gov (United States)

Tedgren, Åsa Carlsson; Plamondon, Mathieu; Beaulieu, Luc

2015-07-07

The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient/phantom

Observational constraints on phantom power-law cosmology

International Nuclear Information System (INIS)

Kaeonikhom, Chakkrit; Gumjudpai, Burin; Saridakis, Emmanuel N.

2011-01-01

We investigate phantom cosmology in which the scale factor is a power law, and we use cosmological observations from Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO) and observational Hubble data, in order to impose complete constraints on the model parameters. We find that the power-law exponent is β∼-6.51 -0.25 +0.24 , while the Big Rip is realized at t s ∼104.5 -2.0 +1.9 Gyr, in 1σ confidence level. Providing late-time asymptotic expressions, we find that the dark-energy equation-of-state parameter at the Big Rip remains finite and equal to w DE ∼-1.153, with the dark-energy density and pressure diverging. Finally, we reconstruct the phantom potential.

Incorporation of detailed eye model into polygon-mesh versions of ICRP-110 reference phantoms.

Science.gov (United States)

Nguyen, Thang Tat; Yeom, Yeon Soo; Kim, Han Sung; Wang, Zhao Jun; Han, Min Cheol; Kim, Chan Hyeong; Lee, Jai Ki; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E; Lee, Choonsik; Chung, Beom Sun

2015-11-21

The dose coefficients for the eye lens reported in ICRP 2010 Publication 116 were calculated using both a stylized model and the ICRP-110 reference phantoms, according to the type of radiation, energy, and irradiation geometry. To maintain consistency of lens dose assessment, in the present study we incorporated the ICRP-116 detailed eye model into the converted polygon-mesh (PM) version of the ICRP-110 reference phantoms. After the incorporation, the dose coefficients for the eye lens were calculated and compared with those of the ICRP-116 data. The results showed generally a good agreement between the newly calculated lens dose coefficients and the values of ICRP 2010 Publication 116. Significant differences were found for some irradiation cases due mainly to the use of different types of phantoms. Considering that the PM version of the ICRP-110 reference phantoms preserve the original topology of the ICRP-110 reference phantoms, it is believed that the PM version phantoms, along with the detailed eye model, provide more reliable and consistent dose coefficients for the eye lens.

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.

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.

Quality assurance applied to mammographic equipments using phantoms and software for its evaluation

Energy Technology Data Exchange (ETDEWEB)

Mayo, Patricia, E-mail: p.mayo@titaniast.co [Titania Servicios Tecnologicos S.L., Grupo Dominguis, Apartado 46015, Valencia (Spain); Rodenas, Francisco [Departamento de Matematica Aplicada, Universidad Politecnica de Valencia, Apartado 46022, Valencia (Spain); Manuel Campayo, Juan [Hospital Clinico Universitario de Valencia, Avda. Blasco Ibanez, Apartado 46017, Valencia (Spain); Verdu, Gumersido [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Apartado 46022, Valencia (Spain)

2010-07-21

The image quality assessment in radiographic equipments is a very important item for a complete quality control of the radiographic image chain. The periodic evaluation of the radiographic image quality must guarantee the constancy of this quality to carry out a suitable diagnosis. Mammographic phantom images are usually used to study the quality of images obtained by determined mammographic equipment. The digital image treatment techniques allow to carry out an automatic analysis of the phantom image. In this work we apply some techniques of digital image processing to analyze in an automatic way the image quality of mammographic phantoms, namely CIRS SP01 and RACON for different varying conditions of the mammographic equipment. The CIRS SP01 phantom is usually used in analogic mammographic equipments and the RACON phantom has been specifically developed by authors to be applied to acceptance and constancy tests of the image quality in digital radiographic equipments following recommendations of international associations. The purpose of this work consists in analyzing the image quality for both phantoms by means of an automatic software utility. This analysis allows us to study the functioning of the image chain of the mammographic system in an objective way, so an abnormal functioning of the radiographic equipment might be detected.

Quality assurance applied to mammographic equipments using phantoms and software for its evaluation

International Nuclear Information System (INIS)

Mayo, Patricia; Rodenas, Francisco; Manuel Campayo, Juan; Verdu, Gumersido

2010-01-01

The image quality assessment in radiographic equipments is a very important item for a complete quality control of the radiographic image chain. The periodic evaluation of the radiographic image quality must guarantee the constancy of this quality to carry out a suitable diagnosis. Mammographic phantom images are usually used to study the quality of images obtained by determined mammographic equipment. The digital image treatment techniques allow to carry out an automatic analysis of the phantom image. In this work we apply some techniques of digital image processing to analyze in an automatic way the image quality of mammographic phantoms, namely CIRS SP01 and RACON for different varying conditions of the mammographic equipment. The CIRS SP01 phantom is usually used in analogic mammographic equipments and the RACON phantom has been specifically developed by authors to be applied to acceptance and constancy tests of the image quality in digital radiographic equipments following recommendations of international associations. The purpose of this work consists in analyzing the image quality for both phantoms by means of an automatic software utility. This analysis allows us to study the functioning of the image chain of the mammographic system in an objective way, so an abnormal functioning of the radiographic equipment might be detected.

[The treatment of the phantom pain syndrome with tizanidine].

Science.gov (United States)

Vorobeĭchik, Ia M; Kukushkin, M L; Reshetniak, V K; Ovechkin, A M; Gnezdilov, A V

1997-01-01

The authors carried out estimation of analgetic effect of tisanidin by double blind test in patients with phantom limb pain syndrome. 14 patients took the medicine in a dose of 12 mg/day and 5 patients took placebo at the same dose. Characteristics and intensity of pain were estimated in accordance with McGill pain questionnaire and visual analogue scale. Pain possessed more than one sensory characteristics in the majority of patients. Tisanidin had a significant analgetic influence on all type of phantom limb pain: "neuralgic"--acute, shooting, transitory, "causalgic"--hot, burning, searing, "cramping" pain. Pain sensation did not decrease only in one of 14 patients treated with tisanidin. The authors explain the effectivity of the drug for treatment of phantom limb pain of different sensory modality by variety of the mechanisms of its therapeutic action, the capacity to decrease the releasing of excitatory neurotransmitter amino acids and the influence on alpha 2-adrenoceptors.

The internal radiation dose calculations based on Chinese mathematical phantom

International Nuclear Information System (INIS)

Wang Haiyan; Li Junli; Cheng Jianping; Fan Jiajin

2006-01-01

The internal radiation dose calculations built on Chinese facts become more and more important according to the development of nuclear medicine. the MIRD method developed and consummated by the society of Nuclear Medicine (America) is based on the European and American mathematical phantom and can't fit Chinese well. The transport of γ-ray in the Chinese mathematical phantom was simulated with Monte Carlo method in programs as MCNP4C. the specific absorbed fraction (Φ) of Chinese were calculated and the Chinese Φ database was created. The results were compared with the recommended values by ORNL. the method was proved correct by the coherence when the target organ was the same with the source organ. Else, the difference was due to the different phantom and the choice of different physical model. (authors)

Dark energy: Vacuum fluctuations, the effective phantom phase, and holography

International Nuclear Information System (INIS)

Elizalde, E.; Nojiri, S.; Odintsov, S. D.; Wang Peng

2005-01-01

We aim at the construction of dark energy models without exotic matter but with a phantomlike equation of state (an effective phantom phase). The first model we consider is decaying vacuum cosmology where the fluctuations of the vacuum are taken into account. In this case, the phantom cosmology (with an effective, observational ω being less than -1 ) emerges even for the case of a real dark energy with a physical equation of state parameter ω larger than -1. The second proposal is a generalized holographic model, which is produced by the presence of an infrared cutoff. It also leads to an effective phantom phase, which is not a transient one as in the first model. However, we show that quantum effects are able to prevent its evolution towards a big rip singularity

Modelling of UWB Antenna Perturbed by Human Phantom in Spherical Harmonics Space

DEFF Research Database (Denmark)

Mhedhbi, Meriem; Avrillon, Stephane; Pedersen, Troels

2014-01-01

is attractive for simulation purposes. We propose a simple model for the spherical harmonics coefficients allowing to predict the antenna behavior perturbed by a human phantom. The model is based on knowledge of the spherical harmonic coefficients of antenna in free space and the antenna-phantom distance.......In this paper we study how the antenna radiation pattern is perturbed in the presence of a human phantom in terms of changes in the coefficients of the spherical harmonic antenna representation. The spherical harmonic basis allows for a compact representation of the antenna pattern which...

Image quality assessment using the CD-DISC phantom for vascular radiology and vascular surgery

International Nuclear Information System (INIS)

Struelens, Lara; Hambach, Lionel; Buls, Nico; Smans, Kristien; Malchair, Francoise; Hoornaert, Marie-Therese; Vanhavere, Filip; Bosmans, Hilde

2008-01-01

The purpose of the study was to evaluate image quality (IQ) associated with vascular radiology and vascular surgery procedures in Belgium and to determine reference values for future image quality assessment. IQ was evaluated with the CD-DISC contrast-detail phantom. This circular PMMA phantom contains 225 holes with different diameter and depth, to quantify resolution and contrast. Images of the phantom were acquired for both fluoroscopy and subtraction images on 21 systems. Three observers evaluated the images by determining the threshold contrast visible for every diameter. This results in contrast-detail curves and image quality figures. We observed a large difference in IQ between the centres. No straightforward correlation could be found with radiation dose or other exposure settings. A comparison was made with the image quality evaluation of the systems performed with the TOR[18FG] phantom for fluoroscopy. There is no clear correlation observed between the results of the CD-DISC phantom and the TOR phantom. However, systems with very poor or very good image quality could be detected by both phantoms. An important result is that a 75th percentile reference contrast-detail curve could be proposed to separate the best centres from these with poorer quality. Some centres had also a significantly better image quality than others. Therefore, we introduced also a 25th percentile. Centres with IQ above this value are recommended to lower the dose and work with acceptable rather than excellent image quality. The CD-DISC phantom thus allows to guide the image quality setting

Are phantoms useful for predicting the potential of dose reduction in full-field digital mammography?

International Nuclear Information System (INIS)

Gennaro, Gisella; Katz, Luc; Souchay, Henri; Alberelli, Claudio; Maggio, Cosimo di

2005-01-01

A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future clinical study on the impact of dose reduction on clinical results. Three different mammography phantoms (ACR RMI 156, CIRS 11A and CDMAM 3.4) were imaged by a full-field digital mammography unit (GE Senographe 2000D) at different dose levels. Images were rated by three observers with softcopy reading and scoring methods specific to each phantom. Different types of data analysis were applied to the ACR (American College of Radiology) and the other two phantoms, respectively. With reference to the minimum acceptance score in screen/film accreditation programmes, the ACR phantom showed that about 45% dose reduction could be applied, while keeping the phantom scores above that threshold. A relative comparison was done for CIRS and CDMAM, for which no threshold is defined. CIRS scoring remained close to the reference level down to 40% dose reduction, the inter- and intra-observer variability being the main source of uncertainty. Contrast-detail curves provided by CDMAM overlapped down to 50% dose reduction, at least for object contrast values ranging between 30% and 3%. This multi-phantom study shows the potential of further reducing the dose in full-field digital mammography beyond the current values. A common dose reduction factor around 50% seems acceptable for all phantoms. However, caution is required before extrapolating the results for clinical use, given the limitations of these widely used phantoms, mainly related to their limited dynamic range and uniform background