Science.gov

Sample records for adult human phantoms

  1. Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms.

    PubMed

    Na, Yong Hum; Zhang, Binquan; Zhang, Juying; Caracappa, Peter F; Xu, X George

    2010-07-07

    Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms--modeled entirely in mesh surfaces--of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte Carlo

  2. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations.

    PubMed

    Kramer, R; Cassola, V F; Khoury, H J; Vieira, J W; Lima, V J de Melo; Brown, K Robson

    2010-01-07

    Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

  3. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

    NASA Astrophysics Data System (ADS)

    Kramer, R.; Cassola, V. F.; Khoury, H. J.; Vieira, J. W.; de Melo Lima, V. J.; Robson Brown, K.

    2010-01-01

    Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

  4. Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms

    NASA Astrophysics Data System (ADS)

    Hum Na, Yong; Zhang, Binquan; Zhang, Juying; Caracappa, Peter F.; Xu, X. George

    2010-07-01

    Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms—modeled entirely in mesh surfaces—of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte

  5. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: I. Development of the anatomy

    NASA Astrophysics Data System (ADS)

    Cassola, V. F.; de Melo Lima, V. J.; Kramer, R.; Khoury, H. J.

    2010-01-01

    Among computational models, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images of patients, volunteers or cadavers have become popular in recent years. Although being true to nature representations of scanned individuals, voxel phantoms have limitations, especially when walled organs have to be segmented or when volumes of organs or body tissues, like adipose, have to be changed. Additionally, the scanning of patients or volunteers is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the regular anatomy of a person in the upright position, which in turn can influence organ and tissue absorbed or equivalent dose estimates. This study applies tools developed recently in the areas of computer graphics and animated films to the creation and modelling of 3D human organs, tissues, skeletons and bodies based on polygon mesh surfaces. Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been designed using software, such as MakeHuman, Blender, Binvox and ImageJ, based on anatomical atlases, observing at the same time organ masses recommended by the International Commission on Radiological Protection for the male and female reference adult in report no 89. 113 organs, bones and tissues have been modelled in the FASH and the MASH phantoms representing locations for adults in standing posture. Most organ and tissue masses of the voxelized versions agree with corresponding data from ICRP89 within a margin of 2.6%. Comparison with the mesh-based male RPI_AM and female RPI_AF phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

  6. FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: I. Development of the anatomy.

    PubMed

    Cassola, V F; Lima, V J de Melo; Kramer, R; Khoury, H J

    2010-01-07

    Among computational models, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images of patients, volunteers or cadavers have become popular in recent years. Although being true to nature representations of scanned individuals, voxel phantoms have limitations, especially when walled organs have to be segmented or when volumes of organs or body tissues, like adipose, have to be changed. Additionally, the scanning of patients or volunteers is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the regular anatomy of a person in the upright position, which in turn can influence organ and tissue absorbed or equivalent dose estimates. This study applies tools developed recently in the areas of computer graphics and animated films to the creation and modelling of 3D human organs, tissues, skeletons and bodies based on polygon mesh surfaces. Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been designed using software, such as MakeHuman, Blender, Binvox and ImageJ, based on anatomical atlases, observing at the same time organ masses recommended by the International Commission on Radiological Protection for the male and female reference adult in report no 89. 113 organs, bones and tissues have been modelled in the FASH and the MASH phantoms representing locations for adults in standing posture. Most organ and tissue masses of the voxelized versions agree with corresponding data from ICRP89 within a margin of 2.6%. Comparison with the mesh-based male RPI_AM and female RPI_AF phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

  7. MAX06 and FAX06: update of two adult human phantoms for radiation protection dosimetry

    NASA Astrophysics Data System (ADS)

    Kramer, R.; Khoury, H. J.; Vieira, J. W.; Lima, V. J. M.

    2006-07-01

    The International Commission on Radiological Protection (ICRP) is currently preparing new recommendations which will replace those released in ICRP 1991, 1990 Recommendations of the ICRP ICRP Publication 60 (Oxford: Pergamon). The draft report previews a change for the effective dose with respect to the number of organs and tissues to be included in its calculation. In the future, adipose tissue, connective tissue, the extrathoracic airways, the gall bladder, the heart wall, the lymphatic nodes, the prostate and the salivary glands have to be taken into account for the determination of the effective dose. This study reports on a second segmentation of the recently introduced male adult voxel (MAX) and female adult voxel (FAX) phantoms with regard to the new organs and tissues, but also presents a revised representation of the skeletons, which had not been adjusted to ICRP-based volumes in the first release of the two phantoms.

  8. Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations

    NASA Astrophysics Data System (ADS)

    Cassola, V. F.; Milian, F. M.; Kramer, R.; de Oliveira Lira, C. A. B.; Khoury, H. J.

    2011-07-01

    Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also

  9. Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations.

    PubMed

    Cassola, V F; Milian, F M; Kramer, R; de Oliveira Lira, C A B; Khoury, H J

    2011-07-07

    Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also

  10. Neutron dosimetry in organs of an adult human phantom using linacs with multileaf collimator in radiotherapy treatments

    SciTech Connect

    Martinez-Ovalle, S. A.; Barquero, R.; Gomez-Ros, J. M.; Lallena, A. M.

    2012-05-15

    Purpose: To calculate absorbed doses due to neutrons in 87 organs/tissues for anthropomorphic phantoms, irradiated in position supine (head first into the gantry) with orientations anteroposterior (AP) and right-left (RLAT) with a 18 MV accelerator. Conversion factors from monitor units to {mu}Gy per neutron in organs, equivalent doses in organs/tissues, and effective doses, which permit to quantify stochastic risks, are estimated. Methods: MAX06 and FAX06 phantoms were modeled with MCNPX and irradiated with a 18 MV Varian Clinac 2100C/D accelerator whose geometry included a multileaf collimator. Two actual fields of a pelvic treatment were simulated using electron-photon-neutron coupled transport. Absorbed doses due to neutrons were estimated from kerma. Equivalent doses were estimated using the radiation weighting factor corresponding to an average incident neutron energy 0.47 MeV. Statistical uncertainties associated to absorbed doses, as calculated by MCNPX, were also obtained. Results: Largest doses were absorbed in shallowest (with respect to the neutron pathway) organs. In {mu}GyMU{sup -1}, values of 2.66 (for penis) and 2.33 (for testes) were found in MAX06, and 1.68 (for breasts), 1.05 (for lenses of eyes), and 0.94 (for sublingual salivary glands) in FAX06, in AP orientation. In RLAT, the largest doses were found for bone tissues (leg) just at the entrance of the beam in the body (right side in our case). Values, in {mu}GyMU{sup -1}, of 1.09 in upper leg bone right spongiosa, for MAX06, and 0.63 in mandible spongiosa, for FAX06, were found. Except for gonads, liver, and stomach wall, equivalent doses found for FAX06 were, in both orientations, higher than for MAX06. Equivalent doses in AP are higher than in RLAT for all organs/tissues other than brain and liver. Effective doses of 12.6 and 4.1 {mu}SvMU{sup -1} were found for AP and RLAT, respectively. The organs/tissues with larger relative contributions to the effective dose were testes and breasts, in

  11. Neutron dosimetry in organs of an adult human phantom using linacs with multileaf collimator in radiotherapy treatments.

    PubMed

    Martinez-Ovalle, S A; Barquero, R; Gomez-Ros, J M; Lallena, A M

    2012-05-01

    To calculate absorbed doses due to neutrons in 87 organs/tissues for anthropomorphic phantoms, irradiated in position supine (head first into the gantry) with orientations anteroposterior (AP) and right-left (RLAT) with a 18 MV accelerator. Conversion factors from monitor units to μGy per neutron in organs, equivalent doses in organs/tissues, and effective doses, which permit to quantify stochastic risks, are estimated. MAX06 and FAX06 phantoms were modeled with MCNPX and irradiated with a 18 MV Varian Clinac 2100C/D accelerator whose geometry included a multileaf collimator. Two actual fields of a pelvic treatment were simulated using electron-photon-neutron coupled transport. Absorbed doses due to neutrons were estimated from kerma. Equivalent doses were estimated using the radiation weighting factor corresponding to an average incident neutron energy 0.47 MeV. Statistical uncertainties associated to absorbed doses, as calculated by MCNPX, were also obtained. Largest doses were absorbed in shallowest (with respect to the neutron pathway) organs. In μGyMU(-1), values of 2.66 (for penis) and 2.33 (for testes) were found in MAX06, and 1.68 (for breasts), 1.05 (for lenses of eyes), and 0.94 (for sublingual salivary glands) in FAX06, in AP orientation. In RLAT, the largest doses were found for bone tissues (leg) just at the entrance of the beam in the body (right side in our case). Values, in μGyMU(-1), of 1.09 in upper leg bone right spongiosa, for MAX06, and 0.63 in mandible spongiosa, for FAX06, were found. Except for gonads, liver, and stomach wall, equivalent doses found for FAX06 were, in both orientations, higher than for MAX06. Equivalent doses in AP are higher than in RLAT for all organs/tissues other than brain and liver. Effective doses of 12.6 and 4.1 μSvMU(-1) were found for AP and RLAT, respectively. The organs/tissues with larger relative contributions to the effective dose were testes and breasts, in AP, and breasts and red marrow, in RLAT

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

    SciTech Connect

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

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

    PubMed

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

    2015-07-01

    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. 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. 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-law descriptions of the phantom images

  14. Construction of Chinese adult male phantom library and its application in the virtual calibration of in vivo measurement.

    PubMed

    Chen, Yizheng; Qiu, Rui; Li, Chunyan; Wu, Zhen; Li, Junli

    2016-03-07

    In vivo measurement is a main method of internal contamination evaluation, particularly for large numbers of people after a nuclear accident. Before the practical application, it is necessary to obtain the counting efficiency of the detector by calibration. The virtual calibration based on Monte Carlo simulation usually uses the reference human computational phantom, and the morphological difference between the monitored personnel with the calibrated phantom may lead to the deviation of the counting efficiency. Therefore, a phantom library containing a wide range of heights and total body masses is needed. In this study, a Chinese reference adult male polygon surface (CRAM_S) phantom was constructed based on the CRAM voxel phantom, with the organ models adjusted to match the Chinese reference data. CRAM_S phantom was then transformed to sitting posture for convenience in practical monitoring. Referring to the mass and height distribution of the Chinese adult male, a phantom library containing 84 phantoms was constructed by deforming the reference surface phantom. Phantoms in the library have 7 different heights ranging from 155 cm to 185 cm, and there are 12 phantoms with different total body masses in each height. As an example of application, organ specific and total counting efficiencies of Ba-133 were calculated using the MCNPX code, with two series of phantoms selected from the library. The influence of morphological variation on the counting efficiency was analyzed. The results show only using the reference phantom in virtual calibration may lead to an error of 68.9% for total counting efficiency. Thus the influence of morphological difference on virtual calibration can be greatly reduced using the phantom library with a wide range of masses and heights instead of a single reference phantom.

  15. Construction of Chinese adult male phantom library and its application in the virtual calibration of in vivo measurement

    NASA Astrophysics Data System (ADS)

    Chen, Yizheng; Qiu, Rui; Li, Chunyan; Wu, Zhen; Li, Junli

    2016-03-01

    In vivo measurement is a main method of internal contamination evaluation, particularly for large numbers of people after a nuclear accident. Before the practical application, it is necessary to obtain the counting efficiency of the detector by calibration. The virtual calibration based on Monte Carlo simulation usually uses the reference human computational phantom, and the morphological difference between the monitored personnel with the calibrated phantom may lead to the deviation of the counting efficiency. Therefore, a phantom library containing a wide range of heights and total body masses is needed. In this study, a Chinese reference adult male polygon surface (CRAM_S) phantom was constructed based on the CRAM voxel phantom, with the organ models adjusted to match the Chinese reference data. CRAMS phantom was then transformed to sitting posture for convenience in practical monitoring. Referring to the mass and height distribution of the Chinese adult male, a phantom library containing 84 phantoms was constructed by deforming the reference surface phantom. Phantoms in the library have 7 different heights ranging from 155 cm to 185 cm, and there are 12 phantoms with different total body masses in each height. As an example of application, organ specific and total counting efficiencies of Ba-133 were calculated using the MCNPX code, with two series of phantoms selected from the library. The influence of morphological variation on the counting efficiency was analyzed. The results show only using the reference phantom in virtual calibration may lead to an error of 68.9% for total counting efficiency. Thus the influence of morphological difference on virtual calibration can be greatly reduced using the phantom library with a wide range of masses and heights instead of a single reference phantom.

  16. Composition of MRI phantom equivalent to human tissues

    SciTech Connect

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

    2005-10-15

    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{sub 3} as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN{sub 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{sub 3} and agarose are varied from 0-140 {mu}mol/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.

  17. Absorbed Dose Calculations Using Mesh-based Human Phantoms And Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Kramer, Richard

    2011-08-01

    Health risks attributable to the exposure to ionizing radiation are considered to be a function of the absorbed or equivalent dose to radiosensitive organs and tissues. However, as human tissue cannot express itself in terms of equivalent dose, exposure models have to be used to determine the distribution of equivalent dose throughout the human body. An exposure model, be it physical or computational, consists of a representation of the human body, called phantom, plus a method for transporting ionizing radiation through the phantom and measuring or calculating the equivalent dose to organ and tissues of interest. The FASH2 (Female Adult meSH) and the MASH2 (Male Adult meSH) computational phantoms have been developed at the University of Pernambuco in Recife/Brazil based on polygon mesh surfaces using open source software tools and anatomical atlases. Representing standing adults, FASH2 and MASH2 have organ and tissue masses, body height and body mass adjusted to the anatomical data published by the International Commission on Radiological Protection for the reference male and female adult. For the purposes of absorbed dose calculations the phantoms have been coupled to the EGSnrc Monte Carlo code, which can transport photons, electrons and positrons through arbitrary media. This paper reviews the development of the FASH2 and the MASH2 phantoms and presents dosimetric applications for X-ray diagnosis and for prostate brachytherapy.

  18. All about FAX: a Female Adult voXel phantom for Monte Carlo calculation in radiation protection dosimetry

    NASA Astrophysics Data System (ADS)

    Kramer, R.; Khoury, H. J.; Vieira, J. W.; Loureiro, E. C. M.; Lima, V. J. M.; Lima, F. R. A.; Hoff, G.

    2004-12-01

    The International Commission on Radiological Protection (ICRP) has created a task group on dose calculations, which, among other objectives, should replace the currently used mathematical MIRD phantoms by voxel phantoms. Voxel phantoms are based on digital images recorded from scanning of real persons by computed tomography or magnetic resonance imaging (MRI). Compared to the mathematical MIRD phantoms, voxel phantoms are true to the natural representations of a human body. Connected to a radiation transport code, voxel phantoms serve as virtual humans for which equivalent dose to organs and tissues from exposure to ionizing radiation can be calculated. The principal database for the construction of the FAX (Female Adult voXel) phantom consisted of 151 CT images recorded from scanning of trunk and head of a female patient, whose body weight and height were close to the corresponding data recommended by the ICRP in Publication 89. All 22 organs and tissues at risk, except for the red bone marrow and the osteogenic cells on the endosteal surface of bone ('bone surface'), have been segmented manually with a technique recently developed at the Departamento de Energia Nuclear of the UFPE in Recife, Brazil. After segmentation the volumes of the organs and tissues have been adjusted to agree with the organ and tissue masses recommended by ICRP for the Reference Adult Female in Publication 89. Comparisons have been made with the organ and tissue masses of the mathematical EVA phantom, as well as with the corresponding data for other female voxel phantoms. The three-dimensional matrix of the segmented images has eventually been connected to the EGS4 Monte Carlo code. Effective dose conversion coefficients have been calculated for exposures to photons, and compared to data determined for the mathematical MIRD-type phantoms, as well as for other voxel phantoms.

  19. All about FAX: a Female Adult voXel phantom for Monte Carlo calculation in radiation protection dosimetry.

    PubMed

    Kramer, R; Khoury, H J; Vieira, J W; Loureiro, E C M; Lima, V J M; Lima, F R A; Hoff, G

    2004-12-07

    The International Commission on Radiological Protection (ICRP) has created a task group on dose calculations, which, among other objectives, should replace the currently used mathematical MIRD phantoms by voxel phantoms. Voxel phantoms are based on digital images recorded from scanning of real persons by computed tomography or magnetic resonance imaging (MRI). Compared to the mathematical MIRD phantoms, voxel phantoms are true to the natural representations of a human body. Connected to a radiation transport code, voxel phantoms serve as virtual humans for which equivalent dose to organs and tissues from exposure to ionizing radiation can be calculated. The principal database for the construction of the FAX (Female Adult voXel) phantom consisted of 151 CT images recorded from scanning of trunk and head of a female patient, whose body weight and height were close to the corresponding data recommended by the ICRP in Publication 89. All 22 organs and tissues at risk, except for the red bone marrow and the osteogenic cells on the endosteal surface of bone ('bone surface'), have been segmented manually with a technique recently developed at the Departamento de Energia Nuclear of the UFPE in Recife, Brazil. After segmentation the volumes of the organs and tissues have been adjusted to agree with the organ and tissue masses recommended by ICRP for the Reference Adult Female in Publication 89. Comparisons have been made with the organ and tissue masses of the mathematical EVA phantom, as well as with the corresponding data for other female voxel phantoms. The three-dimensional matrix of the segmented images has eventually been connected to the EGS4 Monte Carlo code. Effective dose conversion coefficients have been calculated for exposures to photons, and compared to data determined for the mathematical MIRD-type phantoms, as well as for other voxel phantoms.

  20. Thermal human phantom for testing of millimeter wave cameras

    NASA Astrophysics Data System (ADS)

    Palka, Norbert; Ryniec, Radoslaw; Piszczek, Marek; Szustakowski, Mieczyslaw; Zyczkowski, Marek; Kowalski, Marcin

    2012-06-01

    Screening cameras working in millimetre band gain more and more interest among security society mainly due to their capability of finding items hidden under clothes. Performance of commercially available passive cameras is still limited due to not sufficient resolution and contrast in comparison to other wavelengths (visible or infrared range). Testing of such cameras usually requires some persons carrying guns, bombs or knives. Such persons can have different clothes or body temperature, what makes the measurements even more ambiguous. To avoid such situations we built a moving phantom of human body. The phantom consists of a polystyrene manikin which is covered with a number of small pipes with water. Pipes were next coated with a silicone "skin". The veins (pipes) are filled with water heated up to 37 C degrees to obtain the same temperature as human body. The phantom is made of non-metallic materials and is placed on a moving wirelessly-controlled platform with four wheels. The phantom can be dressed with a set of ordinary clothes and can be equipped with some dangerous (guns, bombs) and non-dangerous items. For tests we used a passive commercially available camera TS4 from ThruVision Systems Ltd. operating at 250 GHz. We compared the images taken from phantom and a man and we obtained good similarity both for naked as well as dressed man/phantom case. We also tested the phantom with different sets of clothes and hidden items and we got good conformity with persons.

  1. Specific absorbed fractions of electrons and photons for Rad-HUMAN phantom using Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Cheng, Meng-Yun; Long, Peng-Cheng; Hu, Li-Qin

    2015-07-01

    The specific absorbed fractions (SAF) for self- and cross-irradiation are effective tools for the internal dose estimation of inhalation and ingestion intakes of radionuclides. A set of SAFs of photons and electrons were calculated using the Rad-HUMAN phantom, which is a computational voxel phantom of a Chinese adult female that was created using the color photographic image of the Chinese Visible Human (CVH) data set by the FDS Team. The model can represent most Chinese adult female anatomical characteristics and can be taken as an individual phantom to investigate the difference of internal dose with Caucasians. In this study, the emission of mono-energetic photons and electrons of 10 keV to 4 MeV energy were calculated using the Monte Carlo particle transport calculation code MCNP. Results were compared with the values from ICRP reference and ORNL models. The results showed that SAF from the Rad-HUMAN have similar trends but are larger than those from the other two models. The differences were due to the racial and anatomical differences in organ mass and inter-organ distance. The SAFs based on the Rad-HUMAN phantom provide an accurate and reliable data for internal radiation dose calculations for Chinese females. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03040000), National Natural Science Foundation of China (910266004, 11305205, 11305203) and National Special Program for ITER (2014GB112001)

  2. Comparison of internal dosimetry factors for three classes of adult computational phantoms with emphasis on I-131 in the thyroid.

    PubMed

    Lamart, Stephanie; Bouville, Andre; Simon, Steven L; Eckerman, Keith F; Melo, Dunstana; Lee, Choonsik

    2011-11-21

    The S values for 11 major target organs for I-131 in the thyroid were compared for three classes of adult computational human phantoms: stylized, voxel and hybrid phantoms. In addition, we compared specific absorbed fractions (SAFs) with the thyroid as a source region over a broader photon energy range than the x- and gamma-rays of I-131. The S and SAF values were calculated for the International Commission on Radiological Protection (ICRP) reference voxel phantoms and the University of Florida (UF) hybrid phantoms by using the Monte Carlo transport method, while the S and SAF values for the Oak Ridge National Laboratory (ORNL) stylized phantoms were obtained from earlier publications. Phantoms in our calculations were for adults of both genders. The 11 target organs and tissues that were selected for the comparison of S values are brain, breast, stomach wall, small intestine wall, colon wall, heart wall, pancreas, salivary glands, thyroid, lungs and active marrow for I-131 and thyroid as a source region. The comparisons showed, in general, an underestimation of S values reported for the stylized phantoms compared to the values based on the ICRP voxel and UF hybrid phantoms and relatively good agreement between the S values obtained for the ICRP and UF phantoms. Substantial differences were observed for some organs between the three types of phantoms. For example, the small intestine wall of ICRP male phantom and heart wall of ICRP female phantom showed up to eightfold and fourfold greater S values, respectively, compared to the reported values for the ORNL phantoms. UF male and female phantoms also showed significant differences compared to the ORNL phantom, 4.0-fold greater for the small intestine wall and 3.3-fold greater for the heart wall. In our method, we directly calculated the S values without using the SAFs as commonly done. Hence, we sought to confirm the differences observed in our S values by comparing the SAFs among the phantoms with the thyroid as a

  3. Comparison of internal dosimetry factors for three classes of adult computational phantoms with emphasis on I-131 in the thyroid

    NASA Astrophysics Data System (ADS)

    Lamart, Stephanie; Bouville, Andre; Simon, Steven L.; Eckerman, Keith F.; Melo, Dunstana; Lee, Choonsik

    2011-11-01

    The S values for 11 major target organs for I-131 in the thyroid were compared for three classes of adult computational human phantoms: stylized, voxel and hybrid phantoms. In addition, we compared specific absorbed fractions (SAFs) with the thyroid as a source region over a broader photon energy range than the x- and gamma-rays of I-131. The S and SAF values were calculated for the International Commission on Radiological Protection (ICRP) reference voxel phantoms and the University of Florida (UF) hybrid phantoms by using the Monte Carlo transport method, while the S and SAF values for the Oak Ridge National Laboratory (ORNL) stylized phantoms were obtained from earlier publications. Phantoms in our calculations were for adults of both genders. The 11 target organs and tissues that were selected for the comparison of S values are brain, breast, stomach wall, small intestine wall, colon wall, heart wall, pancreas, salivary glands, thyroid, lungs and active marrow for I-131 and thyroid as a source region. The comparisons showed, in general, an underestimation of S values reported for the stylized phantoms compared to the values based on the ICRP voxel and UF hybrid phantoms and relatively good agreement between the S values obtained for the ICRP and UF phantoms. Substantial differences were observed for some organs between the three types of phantoms. For example, the small intestine wall of ICRP male phantom and heart wall of ICRP female phantom showed up to eightfold and fourfold greater S values, respectively, compared to the reported values for the ORNL phantoms. UF male and female phantoms also showed significant differences compared to the ORNL phantom, 4.0-fold greater for the small intestine wall and 3.3-fold greater for the heart wall. In our method, we directly calculated the S values without using the SAFs as commonly done. Hence, we sought to confirm the differences observed in our S values by comparing the SAFs among the phantoms with the thyroid as a

  4. Human torso phantom for imaging of heart with realistic modes of cardiac and respiratory motion

    DOEpatents

    Boutchko, Rostyslav; Balakrishnan, Karthikayan; Gullberg, Grant T; O& #x27; Neil, James P

    2013-09-17

    A human torso phantom and its construction, wherein the phantom mimics respiratory and cardiac cycles in a human allowing acquisition of medical imaging data under conditions simulating patient cardiac and respiratory motion.

  5. Space radiation absorbed dose distribution in a human phantom

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  6. Space radiation absorbed dose distribution in a human phantom

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  7. Space radiation absorbed dose distribution in a human phantom.

    PubMed

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

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

    SciTech Connect

    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.

    2013-04-15

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Space Radiation Absorbed Dose Distribution in a Human Phantom Torso

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Yang, T.; Atwell, W.

    2000-01-01

    The flight of a human phantom torso with head that containing active dosimeters at 5 organ sites and 1400 TLDs distributed in 34 1" thick sections is described. Experimental dose rates and quality factors are compared with calculations for shielding distributions at the sites using the Computerized Anatomical Male (CAM) model. The measurements were complemented with those obtained from other instruments. These results have provided the most comprehensive data set to map the dose distribution inside a human and to assess the accuracy of radiation transport models and astronaut radiation risk.

  11. Comparison of two types of adult phantoms in terms of organ doses from diagnostic CT procedures

    NASA Astrophysics Data System (ADS)

    Liu, Haikuan; Gu, Jianwei; Caracappa, Peter F.; Xu, X. George

    2010-03-01

    The rapidly increasing number of diagnostic computed tomography (CT) procedures in the recent decades has spurred heightened concern over the potential risk to patients. Although an accurate organ dose assessment tool has now become highly desirable, existing software packages depend on stylized computational phantoms that were originally developed more than 40 years ago, exhibiting very large discrepancies when compared with phantoms that are anatomically realistic. However, past comparative studies did not focus on CT protocols for adult patients. This study was designed to quantitatively compare two types of phantoms, the stylized phantoms and a pair of recently developed RPI-adult male and adult female (RPI-AM and RPI-AF) phantoms, for various CT scanning protocols involving the chest, abdomen-pelvis and chest-abdomen-pelvis. Organ doses were based on Monte Carlo simulations using the MCNPX code and a detailed CT scanner model for the GE LightSpeed 16. Results are presented as ratios of organ doses from the stylized phantoms to those from the RPI phantoms. It is found that, for most organs contained in the scan volume, the ratios were within the range of 0.75-1.16. However, the stomach doses are significantly different and the ratio is found to be up to 1.86 in male phantoms and 2.29 in the female phantoms due to the anatomical differences between the two types of phantoms. Organs that lie near a scan boundary also exhibit a significant relative difference in organ doses between the two types of phantoms. This study concludes that, due to relatively low x-ray energies, CT doses are very sensitive to organ shape, size and position, and thus anatomically realistic phantoms should be used to avoid the dose uncertainties caused by the lack of anatomical realism. The new phantoms, such as the RPI-AM and AF phantoms that are designed using advanced surface meshes, are deformable and will make it possible to match the anatomy of a specific patient leading to further

  12. The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Maynard, Matthew R.; Geyer, John W.; Aris, John P.; Shifrin, Roger Y.; Bolch, Wesley

    2011-08-01

    Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR™ and then imported to the 3D modeling software package Rhinoceros™ for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in

  13. A realistic phantom for validating MRI-based synthetic CT images of the human skull.

    PubMed

    Soliman, Abraam S; Burns, Levi; Owrangi, Amir; Lee, Young; Song, William Y; Stanisz, Greg; Chugh, Brige P

    2017-06-23

    To introduce a new realistic human skull phantom for the validation of synthetic CT images of cortical bone from ultra-short echo-time (UTE) sequences. A human skull of an adult female was utilized as a realistic representation of skull cortical bone. The skull was stabilized in a special acrylic container and was filled with contrast agents that have T1 and T2 relaxation times similar to human brain. The phantom was MR scanned at 3T with UTE and T2 -weighted sequences, followed by CT. A clustering approach was developed to extract the cortical bone signal from MR images. T2∗ maps of the skull were calculated. Synthetic CT images of the bone were compared to cortical bone signal extracted from CT images and confounding factors, such as registration errors, were analyzed. Dice similarity coefficient (DSC) of UTE-detected cortical bone was 0.84 and gradually decreased with decreasing number of spokes. DSC did not significantly depend on echo-time. Registration errors were found to be significant confounding factors, with 25% decrease in DSC for consistent 2 mm error at each axis. This work introduced a new realistic human skull phantom, specifically for the evaluation and analysis of synthetic CT images of cortical bone. © 2017 American Association of Physicists in Medicine.

  14. Radiation dose evaluation of dental cone beam computed tomography using an anthropomorphic adult head phantom

    NASA Astrophysics Data System (ADS)

    Wu, Jay; Shih, Cheng-Ting; Ho, Chang-hung; Liu, Yan-Lin; Chang, Yuan-Jen; Min Chao, Max; Hsu, Jui-Ting

    2014-11-01

    Dental cone beam computed tomography (CBCT) provides high-resolution tomographic images and has been gradually used in clinical practice. Thus, it is important to examine the amount of radiation dose resulting from dental CBCT examinations. In this study, we developed an in-house anthropomorphic adult head phantom to evaluate the level of effective dose. The anthropomorphic phantom was made of acrylic and filled with plaster to replace the bony tissue. The contour of the head was extracted from a set of adult computed tomography (CT) images. Different combinations of the scanning parameters of CBCT were applied. Thermoluminescent dosimeters (TLDs) were used to measure the absorbed doses at 19 locations in the head and neck regions. The effective doses measured using the proposed phantom at 65, 75, and 85 kVp in the D-mode were 72.23, 100.31, and 134.29 μSv, respectively. In the I-mode, the effective doses were 108.24, 190.99, and 246.48 μSv, respectively. The maximum percent error between the doses measured by the proposed phantom and the Rando phantom was l4.90%. Therefore, the proposed anthropomorphic adult head phantom is applicable for assessing the radiation dose resulting from clinical dental CBCT.

  15. Monte Carlo simulations for external neutron dosimetry based on the visible Chinese human phantom

    NASA Astrophysics Data System (ADS)

    Zhang, Guozhi; Liu, Qian; Luo, Qingming

    2007-12-01

    A group of Monte Carlo simulations has been performed for external neutron dosimetry calculation based on a whole-body anatomical model, the visible Chinese human (VCH) phantom, which was newly developed from high-resolution cryosectional color photographic images of a healthy Chinese adult male cadaver. Physical characteristics of the VCH computational phantom that consists of 230 × 120 × 892 voxels corresponding to an element volume of 2 × 2 × 2 mm3 are evaluated through comparison against a variety of other anthropomorphic models. Organ-absorbed doses and the effective doses for monoenergic neutron beams ranging from 10-9 MeV to 10 GeV under six idealized irradiation geometries (AP, PA, LLAT, RLAT, ROT and ISO) were calculated using the Monte Carlo code MCNPX2.5. Absorbed dose results for selected organs and the effective doses are presented in the form of tables. Dose results are also compared with currently available neutron data form ICRP Publication 74 and those of VIP-Man. Anatomical variations between different models, as well as their influence on dose distributions, are explored. Detailed information derived from the VCH phantom is able to lend quantitative references to the widespread application of human computational models in radiology.

  16. Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination.

    PubMed

    Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

    2017-03-21

    The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm(-2) in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an

  17. Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

    2017-03-01

    The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm-2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an

  18. S values for 131I based on the ICRP adult voxel phantoms

    PubMed Central

    Lamart, Stephanie; Simon, Steven L.; Bouville, Andre; Moroz, Brian E.; Lee, Choonsik

    2016-01-01

    To improve the estimates of organ doses from nuclear medicine procedures using 131I, the authors calculated a comprehensive set of 131I S values, defined as absorbed doses in target tissues per unit of nuclear transition in source regions, for different source and target combinations. The authors used the latest reference adult male and female voxel phantoms published by the International Commission on Radiological Protection (ICRP Publication 110) and the 131I photon and electron spectra from the ICRP Publication 107 to perform Monte Carlo radiation transport calculations using MCNPX2.7 to compute the S values. For each phantom, the authors simulated 55 source regions with an assumed uniform distribution of 131I. They computed the S values for 42 target tissues directly, without calculating specific absorbed fractions. From these calculations, the authors derived a comprehensive set of S values for 131I for 55 source regions and 42 target tissues in the ICRP male and female voxel phantoms. Compared with the stylised phantoms from Oak Ridge National Laboratory (ORNL) that consist of 22 source regions and 24 target regions, the new data set includes 1662 additional S values corresponding to additional combinations of source–target tissues that are not available in the stylised phantoms. In a comparison of S values derived from the ICRP and ORNL phantoms, the authors found that the S values to the radiosensitive tissues in the ICRP phantoms were 1.1 (median, female) and 1.3 (median, male) times greater than the values based on the ORNL phantoms. However, for several source–target pairs, the difference was up to 10-fold. The new set of S values can be applied prospectively or retrospectively to the calculation of radiation doses in adults internally exposed to 131I, including nuclear medicine patients treated for thyroid cancer or hyperthyroidism. PMID:25829162

  19. S values for 131I based on the ICRP adult voxel phantoms.

    PubMed

    Lamart, Stephanie; Simon, Steven L; Bouville, Andre; Moroz, Brian E; Lee, Choonsik

    2016-01-01

    To improve the estimates of organ doses from nuclear medicine procedures using (131)I, the authors calculated a comprehensive set of (131)I S values, defined as absorbed doses in target tissues per unit of nuclear transition in source regions, for different source and target combinations. The authors used the latest reference adult male and female voxel phantoms published by the International Commission on Radiological Protection (ICRP Publication 110) and the (131)I photon and electron spectra from the ICRP Publication 107 to perform Monte Carlo radiation transport calculations using MCNPX2.7 to compute the S values. For each phantom, the authors simulated 55 source regions with an assumed uniform distribution of (131)I. They computed the S values for 42 target tissues directly, without calculating specific absorbed fractions. From these calculations, the authors derived a comprehensive set of S values for (131)I for 55 source regions and 42 target tissues in the ICRP male and female voxel phantoms. Compared with the stylised phantoms from Oak Ridge National Laboratory (ORNL) that consist of 22 source regions and 24 target regions, the new data set includes 1662 additional S values corresponding to additional combinations of source-target tissues that are not available in the stylised phantoms. In a comparison of S values derived from the ICRP and ORNL phantoms, the authors found that the S values to the radiosensitive tissues in the ICRP phantoms were 1.1 (median, female) and 1.3 (median, male) times greater than the values based on the ORNL phantoms. However, for several source-target pairs, the difference was up to 10-fold. The new set of S values can be applied prospectively or retrospectively to the calculation of radiation doses in adults internally exposed to (131)I, including nuclear medicine patients treated for thyroid cancer or hyperthyroidism.

  20. Inverse modeling for heat conduction problem in human abdominal phantom.

    PubMed

    Huang, Ming; Chen, Wenxi

    2011-01-01

    Noninvasive methods for deep body temperature measurement are based on the principle of heat equilibrium between the thermal sensor and the target location theoretically. However, the measurement position is not able to be definitely determined. In this study, a 2-dimensional mathematical model was built based upon some assumptions for the physiological condition of the human abdomen phantom. We evaluated the feasibility in estimating the internal organs temperature distribution from the readings of the temperature sensors arranged on the skin surface. It is a typical inverse heat conduction problem (IHCP), and is usually mathematically ill-posed. In this study, by integrating some physical and physiological a-priori information, we invoked the quasi-linear (QL) method to reconstruct the internal temperature distribution. The solutions of this method were improved by increasing the accuracy of the sensors and adjusting their arrangement on the outer surface, and eventually reached the state of converging at the best state accurately. This study suggests that QL method is able to reconstruct the internal temperature distribution in this phantom and might be worthy of a further study in an anatomical based model.

  1. A new anthropometric phantom for calibrating in vivo measurements of stable lead in the human leg using X-ray fluorescence

    SciTech Connect

    Spitz, H.; Jenkins, M.; Lodwick, J.; Bornschein, R.

    2000-02-01

    A new anthropometric phantom has been developed for calibrating in vivo measurements of stable lead deposited in bone using x-ray fluorescence. The phantom reproduces the shape of the mid shaft of the adult human leg and is fabricated using polyurethanes and calcium carbonate to produce materials that exhibit the same density, energy transmission, and calcium content as cortical bone, bone marrow, and muscle. The phantom includes a removable tibia fabricated using simulants for cortical bone and bone marrow to which a precise amount of stable lead has been added to cortical bone. The formulations used in fabricating the new anthropometric phantom are much more uniform in density and composition than the conventional phantom made from Plexiglas cylinders filled with plaster-of-Paris. The energy spectrum from an x-ray fluorescence measurement of the phantom using a {sup 109}Cd source is indistinguishable from an in vivo x-ray fluorescence measurement of the human leg, demonstrating that the materials used in the phantom exhibit the same radiological properties as human tissue. Likewise, results from x-ray fluorescence measurements of the phantom exhibit the same positional dependency as the human leg and vary by approximately 36% when, for example, the phantom containing 54 ppm of stable lead in the tibia was rotated by only 15 degrees. The detection limit for a 30 min {sup 109}Cd K shell x-ray fluorescence in vivo measurement is approximately 20 ppm determined from a background measurement using the new phantom containing no added lead in the muscle, bone, or bone marrow. The new anthropometric phantom significantly improves in vivo x-ray fluorescence calibration measurements by (1) faithfully reproducing the anatomy of the human leg, (2) having components that exhibit radiological properties similar to that of human tissue, and (3) providing a realistic calibration standard that can be used for in vivo x-ray fluorescence intercomparison measurements.

  2. Evaluation of organ doses in brachytherapy treatment of uterus cancer using mathematical reference Indian adult phantom.

    PubMed

    Biju, K

    2012-01-01

    Quantifying organ dose to healthy organs during radiotherapy is essential to estimate the radiation risk. Dose factors are generated by simulating radiation transport through an anthropomorphic mathematical phantom representing a reference Indian adult using the Monte Carlo method. The mean organ dose factors (in mGy min(-1) GBq(-1)) are obtained considering the microselectron (192)Ir source and BEBIG (60)Co sources in the uterus of a reference Indian adult female phantom. The present study provides the factors for mean absorbed dose to organs applicable to the Indian female patient population undergoing brachytherapy treatment of uterus cancer. This study also includes a comparison of the dimension of organs in the phantom model with measured values of organs in the various investigated patients.

  3. Transcutaneous electrical nerve stimulation (TENS) for phantom pain and stump pain following amputation in adults.

    PubMed

    Johnson, Mark I; Mulvey, Matthew R; Bagnall, Anne-Marie

    2015-08-18

    This is the first update of a Cochrane review published in Issue 5, 2010 on transcutaneous electrical nerve stimulation (TENS) for phantom pain and stump pain following amputation in adults. Pain may present in a body part that has been amputated (phantom pain) or at the site of amputation (stump pain), or both. Phantom pain and stump pain are complex and multidimensional and the underlying pathophysiology remains unclear. The condition remains a severe burden for those who are affected by it. The mainstay treatments are predominately pharmacological, with increasing acknowledgement of the need for non-drug interventions. TENS has been recommended as a treatment option but there has been no systematic review of available evidence. Hence, the effectiveness of TENS for phantom pain and stump pain is currently unknown. To assess the analgesic effectiveness of TENS for the treatment of phantom pain and stump pain following amputation in adults. For the original version of the review we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, AMED, CINAHL, PEDRO and SPORTDiscus (February 2010). For this update, we searched the same databases for relevant randomised controlled trials (RCTs) from 2010 to 25 March 2015. We only included RCTs investigating the use of TENS for the management of phantom pain and stump pain following an amputation in adults. Two review authors independently assessed trial quality and extracted data. We planned that where available and appropriate, data from outcome measures were to be pooled and presented as an overall estimate of the effectiveness of TENS. In the original review there were no RCTs that examined the effectiveness of TENS for the treatment of phantom pain and stump pain in adults. For this update, we did not identify any additional RCTs for inclusion. There were no RCTs to judge the effectiveness of TENS for the management of phantom pain and stump pain. The published literature on TENS

  4. Comparison of organ dose and dose equivalent for human phantoms of CAM vs. MAX

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Hee Y.; Qualls, Garry D.; Slaba, Tony C.; Cucinotta, Francis A.

    2010-04-01

    For the evaluation of organ dose and dose equivalent of astronauts on space shuttle and the International Space Station (ISS) missions, the CAMERA models of CAM (Computerized Anatomical Male) and CAF (Computerized Anatomical Female) of human tissue shielding have been implemented and used in radiation transport model calculations at NASA. One of new human geometry models to meet the “reference person” of International Commission on Radiological Protection (ICRP) is based on detailed Voxel (volumetric and pixel) phantom models denoted for male and female as MAX (Male Adult voXel) and FAX (Female Adult voXel), respectively. We compared the CAM model predictions of organ doses to those of MAX model, since the MAX model represents the male adult body with much higher fidelity than the CAM model currently used at NASA. Directional body-shielding mass was evaluated for over 1500 target points of MAX for specified organs considered to be sensitive to the induction of stochastic effects. Radiation exposures to solar particle event (SPE), trapped protons, and galactic cosmic ray (GCR) were assessed at the specific sites in the MAX phantom by coupling space radiation transport models with the relevant body-shielding mass. The development of multiple-point body-shielding distributions at each organ made it possible to estimate the mean and variance of organ doses at the specific organ. For the estimate of doses to the blood forming organs (BFOs), data on active marrow distributions in adult were used to weight the bone marrow sites over the human body. The discrete number of target points of MAX organs resulted in a reduced organ dose and dose equivalent compared to the results of CAM organs especially for SPE, and should be further investigated. Differences of effective doses between the two approaches were found to be small (<5%) for GCR.

  5. Input files with ORNL—mathematical phantoms of the human body for MCNP-4B

    NASA Astrophysics Data System (ADS)

    Krstić, D.; Nikezić, D.

    2007-01-01

    Protection against ionizing radiation requires information on the absorbed doses in organs of the human body. Implantation of many dosimeters in the human body is undesirable (or impossible), so the doses in organs are not measurable and some kind of dose calculation has to be applied. Calculation of doses in organs requests: (a) an exact description of the geometry of organs, (b) the chemical constitution of tissues, and (c) appropriate computer programs. The first two items, (a) and (b), make a so-called "phantom". In another words, the "phantom of a human body" is a mathematical representation of the human body including all other relevant information. All organs are represented with geometrical bodies (like cylinders, ellipsoids, tori, cones etc.), which are described with suitable mathematical equations. A corresponding chemical constitution for various types of organ tissues is also defined. MCNP-4B ( Monte Carlo N- Particle) is often used as transport code. Users of this software prepare an "input file" providing all necessary information for program execution. This information includes: (a) source definition—type of ionizing radiation, energy spectrum, and geometry of the source; (b) target definition—material constitution, geometry, location in respect to the source etc.; (c) characterization of absorbing media between the source and target; (d) output tally, etc. This paper presents input files with "human phantoms" for the MCNP-4B code. The input files with "phantoms" were prepared based on publications issued by the Oak Ridge National Laboratory (ORNL). Seven input files relating to different age groups (newborn, 1, 5, 10, 15 years, as well as, male and female adults) are presented here. A test example and comparison with other data found in literature are also given. Program summaryTitle of program: INPUT FILES, AMALE, AFEMALE, AGE15, AGE10, AGE5, AGE01, NEWB Catalogue identifier:ADYF_v1_0 Program summary URL

  6. Organ doses from environmental exposures calculated using voxel phantoms of adults and children

    NASA Astrophysics Data System (ADS)

    Petoussi-Henss, Nina; Schlattl, H.; Zankl, M.; Endo, A.; Saito, K.

    2012-09-01

    This paper presents effective and organ dose conversion coefficients for members of the public due to environmental external exposures, calculated using the ICRP adult male and female reference computational phantoms as well as voxel phantoms of a baby, two children and four adult individual phantoms--one male and three female, one of them pregnant. Dose conversion coefficients are given for source geometries representing environmental radiation exposures, i.e. whole body irradiations from a volume source in air, representing a radioactive cloud, a plane source in the ground at a depth of 0.5 g cm-2, representing ground contamination by radioactive fall-out, and uniformly distributed natural sources in the ground. The organ dose conversion coefficients were calculated employing the Monte Carlo code EGSnrc simulating the photon transport in the voxel phantoms, and are given as effective and equivalent doses normalized to air kerma free-in-air at height 1 m above the ground in Sv Gy-1. The findings showed that, in general, the smaller the body mass of the phantom, the higher the dose. The difference in effective dose between an adult and an infant is 80-90% at 50 keV and less than 40% above 100 keV. Furthermore, dose equivalent rates for photon exposures of several radionuclides for the above environmental exposures were calculated with the most recent nuclear decay data. Data are shown for effective dose, thyroid, colon and red bone marrow. The results are expected to facilitate regulation of exposure to radiation, relating activities of radionuclides distributed in air and ground to dose of the public due to external radiation as well as the investigation of the radiological effects of major radiation accidents such as the recent one in Fukushima and the decision making of several committees.

  7. Development of the two Korean adult tomographic computational phantoms for organ dosimetry

    SciTech Connect

    Lee, Choonsik; Lee, Choonik; Park, Sang-Hyun; Lee, Jai-Ki

    2006-02-15

    Following the previously developed Korean tomographic phantom, KORMAN, two additional whole-body tomographic phantoms of Korean adult males were developed from magnetic resonance (MR) and computed tomography (CT) images, respectively. Two healthy male volunteers, whose body dimensions were fairly representative of the average Korean adult male, were recruited and scanned for phantom development. Contiguous whole body MR images were obtained from one subject exclusive of the arms, while whole-body CT images were acquired from the second individual. A total of 29 organs and tissues and 19 skeletal sites were segmented via image manipulation techniques such as gray-level thresholding, region growing, and manual drawing, in which each of segmented image slice was subsequently reviewed by an experienced radiologist for anatomical accuracy. The resulting phantoms, the MR-based KTMAN-1 (Korean Typical MAN-1) and the CT-based KTMAN-2 (Korean Typical MAN-2), consist of 300x150x344 voxels with a voxel resolution of 2x2x5 mm{sup 3} for both phantoms. Masses of segmented organs and tissues were calculated as the product of a nominal reference density, the prevoxel volume, and the cumulative number of voxels defining each organs or tissue. These organs masses were then compared with those of both the Asian and the ICRP reference adult male. Organ masses within both KTMAN-1 and KTMAN-2 showed differences within 40% of Asian and ICRP reference values, with the exception of the skin, gall bladder, and pancreas which displayed larger differences. The resulting three-dimensional binary file was ported to the Monte Carlo code MCNPX2.4 to calculate organ doses following external irradiation for illustrative purposes. Colon, lung, liver, and stomach absorbed doses, as well as the effective dose, for idealized photon irradiation geometries (anterior-posterior and right lateral) were determined, and then compared with data from two other tomographic phantoms (Asian and Caucasian), and

  8. Posture-specific phantoms representing female and male adults in Monte Carlo-based simulations for radiological protection

    NASA Astrophysics Data System (ADS)

    Cassola, V. F.; Kramer, R.; Brayner, C.; Khoury, H. J.

    2010-08-01

    Does the posture of a patient have an effect on the organ and tissue absorbed doses caused by x-ray examinations? This study aims to find the answer to this question, based on Monte Carlo (MC) simulations of commonly performed x-ray examinations using adult phantoms modelled to represent humans in standing as well as in the supine posture. The recently published FASH (female adult mesh) and MASH (male adult mesh) phantoms have the standing posture. In a first step, both phantoms were updated with respect to their anatomy: glandular tissue was separated from adipose tissue in the breasts, visceral fat was separated from subcutaneous fat, cartilage was segmented in ears, nose and around the thyroid, and the mass of the right lung is now 15% greater than the left lung. The updated versions are called FASH2_sta and MASH2_sta (sta = standing). Taking into account the gravitational effects on organ position and fat distribution, supine versions of the FASH2 and the MASH2 phantoms have been developed in this study and called FASH2_sup and MASH2_sup. MC simulations of external whole-body exposure to monoenergetic photons and partial-body exposure to x-rays have been made with the standing and supine FASH2 and MASH2 phantoms. For external whole-body exposure for AP and PA projection with photon energies above 30 keV, the effective dose did not change by more than 5% when the posture changed from standing to supine or vice versa. Apart from that, the supine posture is quite rare in occupational radiation protection from whole-body exposure. However, in the x-ray diagnosis supine posture is frequently used for patients submitted to examinations. Changes of organ absorbed doses up to 60% were found for simulations of chest and abdomen radiographs if the posture changed from standing to supine or vice versa. A further increase of differences between posture-specific organ and tissue absorbed doses with increasing whole-body mass is to be expected.

  9. Monte Carlo estimation of radiation dose in organs of female and male adult phantoms due to FDG-F18 absorbed in the lungs

    NASA Astrophysics Data System (ADS)

    Belinato, Walmir; Santos, William S.; Silva, Rogério M. V.; Souza, Divanizia N.

    2014-03-01

    The determination of dose conversion factors (S values) for the radionuclide fluorodeoxyglucose (18F-FDG) absorbed in the lungs during a positron emission tomography (PET) procedure was calculated using the Monte Carlo method (MCNPX version 2.7.0). For the obtained dose conversion factors of interest, it was considered a uniform absorption of radiopharmaceutical by the lung of a healthy adult human. The spectrum of fluorine was introduced in the input data file for the simulation. The simulation took place in two adult phantoms of both sexes, based on polygon mesh surfaces called FASH and MASH with anatomy and posture according to ICRP 89. The S values for the 22 internal organs/tissues, chosen from ICRP No. 110, for the FASH and MASH phantoms were compared with the results obtained from a MIRD V phantoms called ADAM and EVA used by the Committee on Medical Internal Radiation Dose (MIRD). We observed variation of more than 100% in S values due to structural anatomical differences in the internal organs of the MASH and FASH phantoms compared to the mathematical phantom.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    PubMed

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

    2012-04-07

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

  12. Computational lymphatic node models in pediatric and adult hybrid phantoms for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Lee, Choonsik; Lamart, Stephanie; Moroz, Brian E.

    2013-03-01

    We developed models of lymphatic nodes for six pediatric and two adult hybrid computational phantoms to calculate the lymphatic node dose estimates from external and internal radiation exposures. We derived the number of lymphatic nodes from the recommendations in International Commission on Radiological Protection (ICRP) Publications 23 and 89 at 16 cluster locations for the lymphatic nodes: extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right) and popliteal (left and right), for different ages (newborn, 1-, 5-, 10-, 15-year-old and adult). We modeled each lymphatic node within the voxel format of the hybrid phantoms by assuming that all nodes have identical size derived from published data except narrow cluster sites. The lymph nodes were generated by the following algorithm: (1) selection of the lymph node site among the 16 cluster sites; (2) random sampling of the location of the lymph node within a spherical space centered at the chosen cluster site; (3) creation of the sphere or ovoid of tissue representing the node based on lymphatic node characteristics defined in ICRP Publications 23 and 89. We created lymph nodes until the pre-defined number of lymphatic nodes at the selected cluster site was reached. This algorithm was applied to pediatric (newborn, 1-, 5-and 10-year-old male, and 15-year-old males) and adult male and female ICRP-compliant hybrid phantoms after voxelization. To assess the performance of our models for internal dosimetry, we calculated dose conversion coefficients, called S values, for selected organs and tissues with Iodine-131 distributed in six lymphatic node cluster sites using MCNPX2.6, a well validated Monte Carlo radiation transport code. Our analysis of the calculations indicates that the S values were significantly affected by the location of the lymph node clusters and that the values increased for

  13. COMPUTATIONAL LYMPHATIC NODE MODELS IN PEDIATRIC AND ADULT HYBRID PHANTOMS FOR RADIATION DOSIMETRY

    PubMed Central

    Lee, Choonsik; Lamart, Stephanie; Moroz, Brian E.

    2013-01-01

    We developed models of lymphatic nodes for 6 pediatric and 2 adult hybrid computational phantoms to calculate the lymphatic node dose estimates from external and internal radiation exposures. We derived the number of lymphatic nodes from the recommendations in International Commission on Radiological Protection (ICRP) Publications 23 and 89 at 16 cluster locations for the lymphatic nodes: extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right), and popliteal (left and right), for different ages (newborn, 1-, 5-, 10-, 15-year-old, and adult). We modeled each lymphatic node within the voxel format of the hybrid phantoms by assuming that all nodes have identical size derived from published data except narrow cluster sites. The lymph nodes were generated by the following algorithm: (1) selection of the lymph node site among the 16 cluster sites; (2) random sampling of the location of the lymph node within a spherical space centered at the chosen cluster site; (3) creation of the sphere or ovoid of tissue representing the node based on lymphatic node characteristics defined in ICRP Publications 23 and 89. We created lymph nodes until the pre-defined number of lymphatic nodes at the selected cluster site was reached. This algorithm was applied to pediatric (newborn, 1-, 5-, and 10-year-old male, and 15-year-old males) and adult male and female ICRP-compliant hybrid phantoms after voxelization. To assess the performance of our models for internal dosimetry, we calculated dose conversion coefficients, called S values, for selected organs and tissues with Iodine-131 distributed in 6 lymphatic node cluster sites using MCNPX2.6, a well validated Monte Carlo radiation transport code. Our analysis of the calculations indicates that the S values were significantly affected by the location of the lymph node clusters and that the values increased for

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

    PubMed Central

    Lichenstein, Sarah D.; Bishop, James H.; Verstynen, Timothy D.; Yeh, Fang-Cheng

    2016-01-01

    Purpose: Diffusion MRI provides a non-invasive way of estimating structural connectivity in the brain. Many studies have used diffusion phantoms as benchmarks to assess the performance of different tractography reconstruction algorithms and assumed that the results can be applied to in vivo studies. Here we examined whether quality metrics derived from a common, publically available, diffusion phantom can reliably predict tractography performance in human white matter tissue. Materials and Methods: We compared estimates of fiber length and fiber crossing among a simple tensor model (diffusion tensor imaging), a more complicated model (ball-and-sticks) and model-free (diffusion spectrum imaging, generalized q-sampling imaging) reconstruction methods using a capillary phantom and in vivo human data (N = 14). Results: Our analysis showed that evaluation outcomes differ depending on whether they were obtained from phantom or human data. Specifically, the diffusion phantom favored a more complicated model over a simple tensor model or model-free methods for resolving crossing fibers. On the other hand, the human studies showed the opposite pattern of results, with the model-free methods being more advantageous than model-based methods or simple tensor models. This performance difference was consistent across several metrics, including estimating fiber length and resolving fiber crossings in established white matter pathways. Conclusions: These findings indicate that the construction of current capillary diffusion phantoms tends to favor complicated reconstruction models over a simple tensor model or model-free methods, whereas the in vivo data tends to produce opposite results. This brings into question the previous phantom-based evaluation approaches and suggests that a more realistic phantom or simulation is necessary to accurately predict the relative performance of different tractography reconstruction methods. PMID:27656122

  15. Monte Carlo simulations of adult and pediatric computed tomography exams: Validation studies of organ doses with physical phantoms

    SciTech Connect

    Long, Daniel J.; Lee, Choonsik; Tien, Christopher; Fisher, Ryan; Hoerner, Matthew R.; Hintenlang, David; Bolch, Wesley E.

    2013-01-15

    Purpose: To validate the accuracy of a Monte Carlo source model of the Siemens SOMATOM Sensation 16 CT scanner using organ doses measured in physical anthropomorphic phantoms. Methods: The x-ray output of the Siemens SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code, MCNPX version 2.6. The resulting source model was able to perform various simulated axial and helical computed tomographic (CT) scans of varying scan parameters, including beam energy, filtration, pitch, and beam collimation. Two custom-built anthropomorphic phantoms were used to take dose measurements on the CT scanner: an adult male and a 9-month-old. The adult male is a physical replica of University of Florida reference adult male hybrid computational phantom, while the 9-month-old is a replica of University of Florida Series B 9-month-old voxel computational phantom. Each phantom underwent a series of axial and helical CT scans, during which organ doses were measured using fiber-optic coupled plastic scintillator dosimeters developed at University of Florida. The physical setup was reproduced and simulated in MCNPX using the CT source model and the computational phantoms upon which the anthropomorphic phantoms were constructed. Average organ doses were then calculated based upon these MCNPX results. Results: For all CT scans, good agreement was seen between measured and simulated organ doses. For the adult male, the percent differences were within 16% for axial scans, and within 18% for helical scans. For the 9-month-old, the percent differences were all within 15% for both the axial and helical scans. These results are comparable to previously published validation studies using GE scanners and commercially available anthropomorphic phantoms. Conclusions: Overall results of this study show that the Monte Carlo source model can be used to accurately and reliably calculate organ doses for patients undergoing a variety of axial or helical CT

  16. Soft 3D-Printed Phantom of the Human Kidney with Collecting System.

    PubMed

    Adams, Fabian; Qiu, Tian; Mark, Andrew; Fritz, Benjamin; Kramer, Lena; Schlager, Daniel; Wetterauer, Ulrich; Miernik, Arkadiusz; Fischer, Peer

    2017-04-01

    Organ models are used for planning and simulation of operations, developing new surgical instruments, and training purposes. There is a substantial demand for in vitro organ phantoms, especially in urological surgery. Animal models and existing simulator systems poorly mimic the detailed morphology and the physical properties of human organs. In this paper, we report a novel fabrication process to make a human kidney phantom with realistic anatomical structures and physical properties. The detailed anatomical structure was directly acquired from high resolution CT data sets of human cadaveric kidneys. The soft phantoms were constructed using a novel technique that combines 3D wax printing and polymer molding. Anatomical details and material properties of the phantoms were validated in detail by CT scan, ultrasound, and endoscopy. CT reconstruction, ultrasound examination, and endoscopy showed that the designed phantom mimics a real kidney's detailed anatomy and correctly corresponds to the targeted human cadaver's upper urinary tract. Soft materials with a tensile modulus of 0.8-1.5 MPa as well as biocompatible hydrogels were used to mimic human kidney tissues. We developed a method of constructing 3D organ models from medical imaging data using a 3D wax printing and molding process. This method is cost-effective means for obtaining a reproducible and robust model suitable for surgical simulation and training purposes.

  17. Dosimetry calculations for internal electron sources using a Korean reference adult stylised phantom.

    PubMed

    Park, S; Lee, J K; Lee, C; Lee, C

    2008-01-01

    Absorbed fractions (AFs) and specific absorbed fractions (SAFs) for internally deposited electron were calculated using a Korean reference adult stylised phantom, where a total of 15 internal organ volumes and external body dimension were designed to match average Korean adult male. The walls of oesophagus, stomach, colon and urinary bladder were additionally divided into the mucosal layer and residual wall to accommodate dose calculation for weakly penetrating electron. The mucosal wall thicknesses were determined by the data reported in the International Commission on Radiological Protection Publication 89 and other literature resources and by direct measurements. The Monte Carlo transport code MCNPX (version 2.5.0) was employed to calculate the electron energy deposited. The SAFs and AFs for monoenergetic electrons with the energies ranging from 10 keV to 2 MeV were calculated. The results were compared with those of the revised Oak Ridge National Laboratory phantoms and showed considerable differences up to 150% in SAFs, whereas no substantial differences were observed in the AFs.

  18. A Monte Carlo approach to assessing 147Pm in the liver of the adult phantom.

    PubMed

    Bhati, S

    1993-06-01

    A low-background phoswich detector is used to detect small amounts of 147Pm--a pure beta-emitting nuclide--present in the liver of an occupational worker. The assessment was based on the measurement of bremsstrahlung radiation produced by the beta particles in the tissue. Computer programs based on Monte Carlo techniques for photon transport have been developed to calculate the response of an external phoswich detector to 1) a 147Pm point source embedded in tissue-equivalent slabs of various thicknesses; and 2) various source distributions of 147Pm in the liver of an adult phantom. The goal is to theoretically calibrate the phoswich detector for each source distribution and to study the variation of maxima of the spectra with the depth of the source in the adult phantom liver and tissue-equivalent slabs. The initial bremsstrahlung photon distribution of 147Pm in water has been computed using Wyard's and Pratt's methods. These calculations have been compared with experimental measurements using Perspex acrylic sheet slabs. Good agreements have been noted when the initial bremsstrahlung spectrum is obtained by using Wyard's method. These results find applications in monitoring the liver burdens in occupational workers handling 147Pm-based radioluminous paints.

  19. [The model of geometrical human body phantom for calculating tissue doses in the service module of the International Space Station].

    PubMed

    Bondarenko, V A; Mitrikas, V G

    2007-01-01

    The model of a geometrical human body phantom developed for calculating the shielding functions of representative points of the body organs and systems is similar to the anthropomorphic phantom. This form of phantom can be integrated with the shielding model of the ISS Russian orbital segment to make analysis of radiation loading of crewmembers in different compartments of the vehicle. Calculation of doses absorbed by the body systems in terms of the representative points makes it clear that doses essentially depend on the phantom spatial orientation (eye direction). It also enables the absorbed dose evaluation from the shielding functions as the mean of the representative points and phantom orientation.

  20. 3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method.

    PubMed

    Abella, V; Miró, R; Juste, B; Verdú, G

    2010-01-01

    The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) (60)Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm(2). Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized. Copyright 2009 Elsevier Ltd. All rights reserved.

  1. Directly detected (55)Mn MRI: application to phantoms for human hyperpolarized (13)C MRI development.

    PubMed

    von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B

    2014-12-01

    In this work we demonstrate for the first time directly detected manganese-55 ((55)Mn) magnetic resonance imaging (MRI) using a clinical 3T MRI scanner designed for human hyperpolarized (13)C clinical studies with no additional hardware modifications. Due to the similar frequency of the (55)Mn and (13)C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective "(13)C" MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, (55)Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical (13)C phantom MRI, at greatly reduced cost as compared with large (13)C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d=8 cm) containing concentrated aqueous sodium permanganate (2.7 M) was scanned rapidly by (55)Mn MRI in a human head coil tuned for (13)C, using a balanced steady state free precession acquisition. The requisite penetration of radiofrequency magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for (55)Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image signal-to-noise ratio of ~60 at 0.5 cm(3) spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP (13)C coils and methods designed for human studies. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Analytical reconstructions of intensity modulated x-ray phase-contrast imaging of human scale phantoms

    PubMed Central

    Włodarczyk, Bartłomiej; Pietrzak, Jakub

    2015-01-01

    This paper presents analytical approach to modeling of a full planar and volumetric acquisition system with image reconstructions originated from partial illumination x-ray phase-contrast imaging at a human scale using graphics processor units. The model is based on x-ray tracing and wave optics methods to develop a numerical framework for predicting the performance of a preclinical phase-contrast imaging system of a human-scaled phantom. In this study, experimental images of simple numerical phantoms and high resolution anthropomorphic phantoms of head and thorax based on non-uniform rational b-spline shapes (NURBS) prove the correctness of the model. Presented results can be used to simulate the performance of partial illumination x-ray phase-contrast imaging system on various preclinical applications. PMID:26600991

  3. Demonstration of motor imagery movement and phantom movement-related neuronal activity in human thalamus.

    PubMed

    Anderson, William S; Weiss, Nirit; Lawson, Herman Christopher; Ohara, Shinji; Rowland, Lance; Lenz, Frederick A

    2011-01-26

    Functional imaging studies show that motor imagery activates multiple structures in the human forebrain. We now show that phantom movements in an amputee and imagined movements in intact individuals elicit responses from neurons in several human thalamic nuclei. These include the somatic sensory nucleus receiving input from the periphery (ventral caudal), and the motor nuclei receiving input from the cerebellum [ventral intermediate (Vim)] and the basal ganglia [ventral oral posterior (Vop)]. Seven neurons in the amputee showed phantom movement-related activity (three Vim, two Vop, and two ventral caudal). In addition, seven neurons in a group of three controls showed motor imagery-related activity (four Vim and three Vop). These studies were performed during single neuron recording sessions in patients undergoing therapeutic treatment of phantom pain, tremor, and chronic pain conditions by thalamic stimulation. The activity of neurons in these sensory and motor nuclei, respectively, may encode the expected sensory consequences and the dynamics of planned movements.

  4. Demonstration of Motor Imagery- and Phantom-Movement Related Neuronal Activity in Human Thalamus

    PubMed Central

    Weiss, Nirit; Lawson, Herman Christopher; Ohara, Shinji; Rowland, Lance; Lenz, Frederick A.

    2010-01-01

    Functional imaging studies demonstrate that motor imagery activates multiple structures in the human forebrain. We now show that phantom movements in an amputee and imagined movements in intact subjects elicit responses from neurons in several human thalamic nuclei. These include the somatic sensory nucleus receiving input from the periphery (ventral caudal – Vc), and the motor nuclei receiving input from the cerebellum (ventral intermediate -Vim) and the basal ganglia (ventral oral posterior - Vop). Seven neurons in the amputee demonstrated phantom movement-related activity (3 Vim, 2 Vop, and 2 Vc). Additionally, seven neurons in a group of three controls demonstrated motor imagery-related activity (4 Vim, and 3 Vop). These studies were performed during single neuron recording sessions in patients undergoing therapeutic treatment of phantom pain, tremor, and chronic pain conditions by thalamic stimulation. The activity of neurons in these sensory and motor nuclei respectively may encode the expected sensory consequences and the dynamics of planned movements. PMID:21150804

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

    PubMed Central

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

    2013-01-01

    This paper describes a heterogeneous phantom that mimics a human thigh with a deep seated tumor, for the purpose of studying the performance of radiofrequency (RF) heating equipment and non-invasive temperature monitoring with magnetic resonance imaging (MRI). The heterogeneous cylindrical phantom was constructed with an outer fat layer surrounding an inner core of phantom material mimicking muscle, tumor and marrow-filled bone. The component materials were formulated to have dielectric and thermal properties similar to human tissues. The dielectric properties of the tissue-mimicking phantom materials were measured with a microwave vector network analyzer and impedance probe over the frequency range of 80 – 500 MHz and at temperatures of 24°C, 37°C, and 45°C. The specific heat values of the component materials were measured using a differential scanning calorimeter over the temperature range of 15 – 55°C. The thermal conductivity value was obtained from fitting the curves obtained from one-dimensional heat transfer measurement. The phantom was used to verify the operation of a cylindrical 4-antenna annular phased array extremity applicator (140 MHz), by examining the proton resonance frequency shift (PRFS) thermal imaging patterns for various magnitude/phase settings (including settings to focus heating in tumor). For muscle and tumor materials, MR imaging was also used to measure T1/T2* values (1.5 Tesla) and to obtain the slope of the PRFS phase change vs. temperature change curve. The dielectric and thermal properties of the phantom materials were in close agreement to well-accepted published results for human tissues. The phantom was able to successfully demonstrate satisfactory operation of the tested heating equipment. The MRI-measured thermal distributions matched the expected patterns for various magnitude/phase settings of the applicator, allowing the phantom to be used as a quality assurance tool. Importantly, the material formulations for the

  6. Computational assessment of mammography accreditation phantom images and correlation with human observer analysis

    NASA Astrophysics Data System (ADS)

    Barufaldi, Bruno; Lau, Kristen C.; Schiabel, Homero; Maidment, D. A.

    2015-03-01

    Routine performance of basic test procedures and dose measurements are essential for assuring high quality of mammograms. International guidelines recommend that breast care providers ascertain that mammography systems produce a constant high quality image, using as low a radiation dose as is reasonably achievable. The main purpose of this research is to develop a framework to monitor radiation dose and image quality in a mixed breast screening and diagnostic imaging environment using an automated tracking system. This study presents a module of this framework, consisting of a computerized system to measure the image quality of the American College of Radiology mammography accreditation phantom. The methods developed combine correlation approaches, matched filters, and data mining techniques. These methods have been used to analyze radiological images of the accreditation phantom. The classification of structures of interest is based upon reports produced by four trained readers. As previously reported, human observers demonstrate great variation in their analysis due to the subjectivity of human visual inspection. The software tool was trained with three sets of 60 phantom images in order to generate decision trees using the software WEKA (Waikato Environment for Knowledge Analysis). When tested with 240 images during the classification step, the tool correctly classified 88%, 99%, and 98%, of fibers, speck groups and masses, respectively. The variation between the computer classification and human reading was comparable to the variation between human readers. This computerized system not only automates the quality control procedure in mammography, but also decreases the subjectivity in the expert evaluation of the phantom images.

  7. Fluid and Thermal Dynamics of Cryogen Sprays Impinging on a Human Tissue Phantom

    PubMed Central

    Franco, Walfre; Vu, Henry; Jia, Wangcun; Nelson, J. Stuart; Aguilar, Guillermo

    2009-01-01

    Cryogen spray cooling (CSC) protects the epidermis from unintended heating during cutaneous laser surgery. The present work investigated the time-dependent flow characteristics of cryogen sprays and correspondent thermal dynamics at the surface of a human tissue phantom. First, a numerical analysis was carried out to evaluate an epoxy block substrate as a human tissue phantom. Next, the velocity and diameter of cryogen droplets were measured simultaneously and correlated with surface temperature of the human tissue phantom during CSC. Finally, velocity and diameter measurements were used to compute the spray number, mass, and kinetic energy fluxes, and temperature measurements were used to compute the surface heat flux. Numerical modeling showed that the thermal response of our phantom was qualitatively similar to that of human stratum corneum and epidermis; quantitatively, thermal responses differed. A simple transformation to map the temperature response of the phantom to that of tissue was derived. Despite the relatively short spurt durations (10 ms, 30 ms, and 50 ms), cryogen delivery is mostly a steady state process with initial and final fluid transients mainly due to the valve dynamics. Thermal transients (16 ms) are longer than fluid transients (4 ms) due to the low thermal diffusivity of human tissues; steady states are comparable in duration (≈10 ms, 30 ms, and 50 ms) although there is an inherent thermal delay (≈12 ms). Steady state temperatures are the lowest surface temperatures experienced by the substrate, independent of spurt duration; hence, longer spurt durations result in larger exposures of the tissue surface to the same lower, steady state temperature as in shorter spurts. Temperatures in human tissue during CSC for the spray system and parameters used herein are estimated to be ≈−19°C at the stratum corneum surface and >0°C across the epidermis. PMID:19045512

  8. Development of phantom for quantitative analyses of human dentin mineral density.

    PubMed

    Hayashi-Sakai, Sachiko; Kondo, Tatsuya; Kasuga, Yuto; Sakamoto, Makoto; Endo, Hideaki; Sakai, Jun

    2015-01-01

    The purpose of the present study was to develop a novel-designed phantom that could be scanned with a sample in the same image, that specialize for quantitative analyses of human dentin mineral density using the X-ray attenuation method. A further attempt was made to demonstrate the intracoronal dentin mineral density using this phantom in mandibular incisors. The phantom prepared with a 15 mm hole in the center of an acrylic resin bar having an outside diameter of 25 mm and 8 small holes (diameter, 3 mm) were made at equal intervals around the center. Liquid dipotassium hydrogen phosphate (K2HPO4) solutions were established at 0.4, 0.6, 0.8 and 1.0 g/cm3, and were arranged to these holes. The mean value of the intracoronal dentin mineral density was 1.486 ± 0.016 g/cm3 in the present study. As the results of the present study corresponded to previous reports, this new phantom was considered to be useful. This phantom enables the analysis of samples that are not readily available by conventional mechanical tests and may facilitate biomechanical investigations using X-ray images. It was suggested that this system is a simple, accurate and novel mineralization measuring system.

  9. Instrumentation for low frequency EIT studies of the human head and its validation in phantom experiments

    NASA Astrophysics Data System (ADS)

    Esler, Brian; Lyons, Thomas; Turovets, Sergei; Tucker, Don

    2010-04-01

    We describe instrumentation for low frequency (< 500 Hz) EIT studies of the human head and its calibration, testing and validation in the phantom experiments. Our EIT system prototype is based on a 256 channel commercial EEG system complimented by the current injection module and lock-in detection software. We have designed and built two types of head phantoms: i) a resistor network and ii) a cylinder tank filled with saline and gel insertions with chemically targeted conductivity values. We have developed a technology for fabricating, handling and storage of agar TX151 gel insertions. Independent and direct conductivity measurements of gel samples have been performed using a HP LCR meter in a four electrode conductivity cell specifically designed and built for this purpose. Measurements of saline conductivity were done with commercially available salinity / conductivity meters. Our inverse conductivity estimates in the phantom experiments with EIDORS and in-house software cross-validate the viability of the EIT-EEG system.

  10. The influence of patient size on dose conversion coefficients: a hybrid phantom study for adult cardiac catheterization

    NASA Astrophysics Data System (ADS)

    Johnson, Perry; Lee, Choonsik; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

    2009-06-01

    In this study, the influence of patient size on organ and effective dose conversion coefficients (DCCs) was investigated for a representative interventional fluoroscopic procedure—cardiac catheterization. The study was performed using hybrid phantoms representing an underweight, average and overweight American adult male. Reference body sizes were determined using the NHANES III database and parameterized based on standing height and total body mass. Organ and effective dose conversion coefficients were calculated for anterior-posterior, posterior-anterior, left anterior oblique and right anterior oblique projections using the Monte Carlo code MCNPX 2.5.0 with the metric dose area product being used as the normalization factor. Results show body size to have a clear influence on DCCs which increased noticeably when body size decreased. It was also shown that if patient size is neglected when choosing a DCC, the organ and effective dose will be underestimated to an underweight patient and will be overestimated to an underweight patient, with errors as large as 113% for certain projections. Results were further compared with those published for a KTMAN-2 Korean patient-specific tomographic phantom. The published DCCs aligned best with the hybrid phantom which most closely matched in overall body size. These results highlighted the need for and the advantages of phantom-patient matching, and it is recommended that hybrid phantoms be used to create a more diverse library of patient-dependent anthropomorphic phantoms for medical dose reconstruction.

  11. Food source provisioning and susceptibility of immature and adult Tribolium castaneum on concrete partially treated with chlorfenapyr (Phantom®)

    USDA-ARS?s Scientific Manuscript database

    A series of experiments were conducted in which adults, pupae, and 4-week-old larvae of Tribolium castaneum (Herbst), the red flour beetle, were exposed separately on concrete arenas partially treated (14.4 % of the total area) with the insecticide chlorfenapyr (Phantom®) at 1.1 g active ingredient/...

  12. Dose comparison between CTDI and the AAPM Report No. 111 methodology in adult, adolescent, and child head phantom

    NASA Astrophysics Data System (ADS)

    Li, Celina L.; Thakur, Yogesh; Ford, Nancy L.

    2017-03-01

    The standard computed tomography dose index (CTDI) metric tends to underestimate scatter radiation in cone beam computed tomography (CBCT) acquisition; therefore, the American Association of Physicists in Medicine (AAPM) Task Group 111 proposed a new dosimetry methodology to measure equilibrium dose at the center of a phantom (z = 0) using a 2-cm thimble ionization chamber. In this study, we implement the CTDI and the AAPM method with a thimble chamber on adult, adolescent, and child head phantoms using the Toshiba Aquilion One CBCT and compare the results to the CTDI measured with a 10-cm pencil chamber. Following the AAPM protocol, the normalized (100 mAs) equilibrium doses (Deq) computed using dose measurements taken in the central hole of the phantom (Deq,c), the peripheral hole of the phantom, (Deq,p), and by the CTDIw equation (Deq,w) are 20.13 +/- 0.19, 21.53 +/- 0.48, and 20.93 +/- 0.40 mGy for adult; 21.55 +/- 0.40, 21.14 +/- 0.43, and 21.08 +/- 0.45 mGy for adolescent; and 24.58 +/- 0.40, 24.92 +/- 0.85, and 24.77 +/- 0.72 mGy for child, respectively. The CTDIw, which measured 17.70, 19.86, and 22.43 mGy for adult, adolescent and child respectively, is about 10% lower than their corresponding Deq's. The extended AAPM method proposed by Deman et al., which estimates the dose profile along the rotational axis (z axis), has demonstrated consistency between theoretical and experimental results for all phantoms. With the introduction of the child and the adolescent head phantoms, we not only have emphasized the practical aspects including relative convenience of the CTDI method and accuracy of the AAPM method, but also proposed a method to approximate Deq for different sized patients.

  13. Phantom system for intraluminal x-ray imaging of the human colon

    NASA Astrophysics Data System (ADS)

    Lifshitz, Ronen; Nawi-Srur, Sivan; Katz, Batia; Milman, Lena; Gubich, Dmitry; Lewkowicz, Shlomo; Kimchy, Yoav

    2017-03-01

    The Check-Cap capsule, C-Scan Cap, performs intraluminal imaging of the human colon based on X-Ray scatter processes. Basic performance of such a system can be demonstrated using various tube-like phantom objects. Also, from a perspective of capsule dynamics, actuators can and have been used for capsule manipulation. Nevertheless the actual situation of a capsule in use is extremely complex, both in terms of the imaging-target object itself and the capsule dynamics within the same. In order to allow study of imaging system performance in a pseudo-clinical environment, a specialized phantom system has been developed. A tissue-equivalent material has been developed in-house, so as to allow simple usage and flexibility for making a wide variety of phantoms, simple tubes as well as extremely complex segments of the human colon which can possibly demonstrate adenomas. The material itself is durable, flexible, and very similar to water in terms of X-Ray scattering. Based on real abdominal CT images, real colon segments have been extracted to become 3D molds, which were used for producing a set of pseudo-clinical human colon segments. In the aspect of capsule and colon dynamics, capsule propulsion within these phantoms is based on the contents, i.e. capsule is hydro-dynamically propelled by surrounding medium rather than actuators. In addition, a system for generating peristaltic contractions along these colon segments has been developed; this system allows stimulation of the colon and the capsule within using arbitrary programmable contraction waves. This phantom system allows demonstration of pseudoclinical imaging scenarios in the lab.

  14. Population of 224 realistic human subject-based computational breast phantoms

    SciTech Connect

    Erickson, David W.; Wells, Jered R.; Sturgeon, Gregory M.; Samei, Ehsan; Dobbins, James T.; Segars, W. Paul; Lo, Joseph Y.

    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

  15. Population of 224 realistic human subject-based computational breast phantoms

    PubMed Central

    Erickson, David W.; Wells, Jered R.; Sturgeon, Gregory M.; Dobbins, James T.; Segars, W. Paul; Lo, Joseph Y.

    2016-01-01

    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

  16. Population of 224 realistic human subject-based computational breast phantoms.

    PubMed

    Erickson, David W; Wells, Jered R; Sturgeon, Gregory M; Samei, Ehsan; Dobbins, James T; Segars, W Paul; Lo, Joseph Y

    2016-01-01

    To create a database of highly realistic and anatomically variable 3D virtual breast phantoms based on dedicated breast computed tomography (bCT) data. 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. 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. 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 of breast types, volumes, densities, and

  17. A second generation of physical anthropomorphic 3D breast phantoms based on human subject data

    NASA Astrophysics Data System (ADS)

    Nolte, Adam; Kiarashi, Nooshin; Samei, Ehsan; Segars, W. P.; Lo, Joseph Y.

    2014-03-01

    Previous fabrication of anthropomorphic breast phantoms has demonstrated their viability as a model for 2D (mammography) and 3D (tomosynthesis) breast imaging systems. Further development of these models will be essential for the evaluation of breast x-ray systems. There is also the potential to use them as the ground truth in virtual clinical trials. The first generation of phantoms was segmented from human subject dedicated breast computed tomography data and fabricated into physical models using highresolution 3D printing. Two variations were made. The first was a multi-material model (doublet) printed with two photopolymers to represent glandular and adipose tissues with the greatest physical contrast available, mimicking 75% and 35% glandular tissue. The second model was printed with a single 75% glandular equivalent photopolymer (singlet) to represent glandular tissue, which can be filled independently with an adipose-equivalent material such as oil. For this study, we have focused on improving the latter, the singlet phantom. First, the temporary oil filler has been replaced with a permanent adipose-equivalent urethane-based polymer. This offers more realistic contrast as compared to the multi-material approach at the expense of air bubbles and pockets that form during the filling process. Second, microcalcification clusters have been included in the singlet model via crushed eggshells, which have very similar chemical composition to calcifications in vivo. The results from these new prototypes demonstrate significant improvement over the first generation of anthropomorphic physical phantoms.

  18. Selected organ dose conversion coefficients for external photons calculated using ICRP adult voxel phantoms and Monte Carlo code FLUKA.

    PubMed

    Patni, H K; Nadar, M Y; Akar, D K; Bhati, S; Sarkar, P K

    2011-11-01

    The adult reference male and female computational voxel phantoms recommended by ICRP are adapted into the Monte Carlo transport code FLUKA. The FLUKA code is then utilised for computation of dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free-in-air for colon, lungs, stomach wall, breast, gonads, urinary bladder, oesophagus, liver and thyroid due to a broad parallel beam of mono-energetic photons impinging in anterior-posterior and posterior-anterior directions in the energy range of 15 keV-10 MeV. The computed DCCs of colon, lungs, stomach wall and breast are found to be in good agreement with the results published in ICRP publication 110. The present work thus validates the use of FLUKA code in computation of organ DCCs for photons using ICRP adult voxel phantoms. Further, the DCCs for gonads, urinary bladder, oesophagus, liver and thyroid are evaluated and compared with results published in ICRP 74 in the above-mentioned energy range and geometries. Significant differences in DCCs are observed for breast, testis and thyroid above 1 MeV, and for most of the organs at energies below 60 keV in comparison with the results published in ICRP 74. The DCCs of female voxel phantom were found to be higher in comparison with male phantom for almost all organs in both the geometries.

  19. Impact of patient weight on tumor visibility based on human-shaped phantom simulation study in PET imaging system

    NASA Astrophysics Data System (ADS)

    Musarudin, M.; Saripan, M. I.; Mashohor, S.; Saad, W. H. M.; Nordin, A. J.; Hashim, S.

    2015-10-01

    Energy window technique has been implemented in all positron emission tomography (PET) imaging protocol, with the aim to remove the unwanted low energy photons. Current practices in our institution however are performed by using default energy threshold level regardless of the weight of the patient. Phantom size, which represents the size of the patient's body, is the factor that determined the level of scatter fraction during PET imaging. Thus, the motivation of this study is to determine the optimum energy threshold level for different sizes of human-shaped phantom, to represent underweight, normal, overweight and obese patients. In this study, the scanner was modeled by using Monte Carlo code, version MCNP5. Five different sizes of elliptical-cylinder shaped of human-sized phantoms with diameter ranged from 15 to 30 cm were modeled. The tumor was modeled by a cylindrical line source filled with 1.02 MeV positron emitters at the center of the phantom. Various energy window widths, in the ranged of 10-50% were implemented to the data. In conclusion, the phantom mass volume did influence the scatter fraction within the volume. Bigger phantom caused more scattering events and thus led to coincidence counts lost. We evaluated the impact of phantom sizes on the sensitivity and visibility of the simulated models. Implementation of wider energy window improved the sensitivity of the system and retained the coincidence photons lost. Visibility of the tumor improved as an appropriate energy window implemented for the different sizes of phantom.

  20. Human Metapneumovirus in Adults

    PubMed Central

    Haas, Lenneke E. M.; Thijsen, Steven F. T.; van Elden, Leontine; Heemstra, Karen A.

    2013-01-01

    Human metapneumovirus (HMPV) is a relative newly described virus. It was first isolated in 2001 and currently appears to be one of the most significant and common human viral infections. Retrospective serologic studies demonstrated the presence of HMPV antibodies in humans more than 50 years earlier. Although the virus was primarily known as causative agent of respiratory tract infections in children, HMPV is an important cause of respiratory infections in adults as well. Almost all children are infected by HMPV below the age of five; the repeated infections throughout life indicate transient immunity. HMPV infections usually are mild and self-limiting, but in the frail elderly and the immunocompromised patients, the clinical course can be complicated. Since culturing the virus is relatively difficult, diagnosis is mostly based on a nucleic acid amplification test, such as reverse transcriptase polymerase chain reaction. To date, no vaccine is available and treatment is supportive. However, ongoing research shows encouraging results. The aim of this paper is to review the current literature concerning HMPV infections in adults, and discuss recent development in treatment and vaccination. PMID:23299785

  1. A 4D CT digital phantom of an individual human brain for perfusion analysis.

    PubMed

    Manniesing, Rashindra; Brune, Christoph; van Ginneken, Bram; Prokop, Mathias

    2016-01-01

    Brain perfusion is of key importance to assess brain function. Modern CT scanners can acquire perfusion maps of the cerebral parenchyma in vivo at submillimeter resolution. These perfusion maps give insights into the hemodynamics of the cerebral parenchyma and are critical for example for treatment decisions in acute stroke. However, the relations between acquisition parameters, tissue attenuation curves, and perfusion values are still poorly understood and cannot be unraveled by studies involving humans because of ethical concerns. We present a 4D CT digital phantom specific for an individual human brain to analyze these relations in a bottom-up fashion. Validation of the signal and noise components was based on 1,000 phantom simulations of 20 patient imaging data. This framework was applied to quantitatively assess the relation between radiation dose and perfusion values, and to quantify the signal-to-noise ratios of penumbra regions with decreasing sizes in white and gray matter. This is the first 4D CT digital phantom that enables to address clinical questions without having to expose the patient to additional radiation dose.

  2. Optical coherence tomography technique for noninvasive blood glucose monitoring: phantom, animal, and human studies

    NASA Astrophysics Data System (ADS)

    Larin, Kirill V.; Ashitkov, Taras V.; Larina, Irina V.; Petrova, Irina Y.; Eledrisi, Mohsen S.; Motamedi, Massoud; Esenaliev, Rinat O.

    2002-06-01

    Continuous noninvasive monitoring of blood glucose concentration can improve management of Diabetes Mellitus, reduce mortality, and considerably improve quality of life of diabetic patients. Recently, we proposed to use the OCT technique for noninvasive glucose monitoring. In this paper, we tested noninvasive blood glucose monitoring with the OCT technique in phantoms, animals, and human subjects. An OCT system with the wavelength of 1300 nm was used in our experiments. Phantom studies performed on aqueous suspensions of polystyrene microspheres and milk showed 3.2% decrease of exponential slope of OCT signals when glucose concentration increased from 0 to 100 mM. Theoretical calculations based on the Mie theory of scattering support the results obtained in phantoms. Bolus glucose injections and glucose clamping experiments were performed in animals (New Zealand rabbits and Yucatan micropigs). Good correlation between changes in the OCT signal slope and actual blood glucose concentration were observed in these experiments. First studies were performed in healthy human subjects (using oral glucose tolerance tests). Dependence of the slope of the OCT signals on the actual blood glucose concentration was similar to that obtained in animal studies. Our studies suggest that the OCT technique can potentially be used for noninvasive blood glucose monitoring.

  3. A 4D CT digital phantom of an individual human brain for perfusion analysis

    PubMed Central

    Brune, Christoph; van Ginneken, Bram; Prokop, Mathias

    2016-01-01

    Brain perfusion is of key importance to assess brain function. Modern CT scanners can acquire perfusion maps of the cerebral parenchyma in vivo at submillimeter resolution. These perfusion maps give insights into the hemodynamics of the cerebral parenchyma and are critical for example for treatment decisions in acute stroke. However, the relations between acquisition parameters, tissue attenuation curves, and perfusion values are still poorly understood and cannot be unraveled by studies involving humans because of ethical concerns. We present a 4D CT digital phantom specific for an individual human brain to analyze these relations in a bottom-up fashion. Validation of the signal and noise components was based on 1,000 phantom simulations of 20 patient imaging data. This framework was applied to quantitatively assess the relation between radiation dose and perfusion values, and to quantify the signal-to-noise ratios of penumbra regions with decreasing sizes in white and gray matter. This is the first 4D CT digital phantom that enables to address clinical questions without having to expose the patient to additional radiation dose. PMID:27917312

  4. Investigation of photothermolysis therapy of human skin diseases using optical phantoms

    NASA Astrophysics Data System (ADS)

    Jedrzejewska-Szczerska, M.; Wróbel, M. S.; Galla, S.; Popov, A. P.; Bykov, A. V.; Tuchin, V. V.; Cenian, A.

    2015-01-01

    Dermatological diseases, such as neurofibroma (Recklinghausen disease) or hemangiomas can be efficiently treated using photothermolysis from laser irradiation. We have utilized a developed 975 nm fiber diode laser as a low-cost alternative over common Nd:YAG lasers. This paper describes the investigations of interaction of 975 nm diode laser radiation-pulses with optical skin phantoms which were designed and manufactured in our laboratory. Such phantoms match the scattering and absorption coefficients of real human skin. Spatial and temporal temperature evolutions during laser irradiation with various laser settings (pulsed and CW mode), were recorded by an IR camera. Subsequent analysis yielded optimum choice of parameters for laser therapy of coetaneous lesions.

  5. Fluence-to-dose conversion coefficients based on the posture modification of Adult Male (AM) and Adult Female (AF) reference phantoms of ICRP 110

    NASA Astrophysics Data System (ADS)

    Galeano, D. C.; Santos, W. S.; Alves, M. C.; Souza, D. N.; Carvalho, A. B.

    2016-04-01

    The aim of this work was to modify the standing posture of the anthropomorphic reference phantoms of ICRP publication 110, AM (Adult Male) and AF (Adult Female), to the sitting posture. The change of posture was performed using the Visual Monte Carlo software (VMC) to rotate the thigh region of the phantoms and position it between the region of the leg and trunk. Scion Image software was used to reconstruct and smooth the knee and hip contours of the phantoms in a sitting posture. For 3D visualization of phantoms, the VolView software was used. In the change of postures, the organ and tissue masses were preserved. The MCNPX was used to calculate the equivalent and effective dose conversion coefficients (CCs) per fluence for photons for six irradiation geometries suggested by ICRP publication 110 (AP, PA, RLAT, LLAT, ROT and ISO) and energy range 0.010-10 MeV. The results were compared between the standing and sitting postures, for both sexes, in order to evaluate the differences of scattering and absorption of radiation for different postures. Significant differences in the CCs for equivalent dose were observed in the gonads, colon, prostate, urinary bladder and uterus, which are present in the pelvic region, and in organs distributed throughout the body, such as the lymphatic nodes, muscle, skeleton and skin, for the phantoms of both sexes. CCs for effective dose showed significant differences of up to 16% in the AP irradiation geometry, 27% in the PA irradiation geometry and 13% in the ROT irradiation geometry. These results demonstrate the importance of using phantoms in different postures in order to obtain more precise conversion coefficients for a given exposure scenario.

  6. Experimental verification of internal dosimetry calculations: Construction of a heterogeneous phantom based on human organs

    NASA Astrophysics Data System (ADS)

    Lauridsen, Bente; Hedemann Jensen, Per

    1987-03-01

    The basic dosimetric quantity in ICRP-publication no. 30 is the aborbed fraction AF( T←S). This parameter is the fraction of energy absorbed in a target organ T per emission of radiation from activity deposited in the source organ S. Based upon this fraction it is possible to calculate the Specific Effective Energy SEE( T← S). From this, the committed effective dose equivalent from an intake of radioactive material can be found, and thus the annual limit of intake for given radionuclides can be determined. A male phantom has been constructed with the aim of measuring the Specific Effective Energy SEE(T←S) in various target organs. Impressions-of real human organs have been used to produce vacuum forms. Tissue equivalent plastic sheets were sucked into the vacuum forms producing a shell with a shape identical to the original organ. Each organ has been made of two shells. The same procedure has been used for the body. Thin tubes through the organs make it possible to place TL dose meters in a matrix so the dose distribution can be measured. The phantom has been supplied with lungs, liver, kidneys, spleen, stomach, bladder, pancreas, and thyroid gland. To select a suitable body liquid for the phantom, laboratory experiments have been made with different liquids and different radionuclides. In these experiments the change in dose rate due to changes in density and composition of the liquid was determined. Preliminary results of the experiments are presented.

  7. SPECT quantitation of iodine-131 concentration in phantoms and human tumors

    SciTech Connect

    Israel, O.; Iosilevsky, G.; Front, D.; Bettman, L.; Frenkel, A.; Ish-Shalom, S.; Steiner, M.; Ben-Harush, M.; Kolodny, G.M. )

    1990-12-01

    The validity of SPECT measurement of iodine-131 ({sup 131}I) concentration was tested in vitro in phantoms and in vivo by measuring bladder urine concentrations. Phantom studies comparing known and SPECT measured concentrations showed a good correlation for {sup 131}I (r = 0.98, s.e.e. = 20.94 counts/voxel) for phantoms of 25 to 127 cc and concentrations of 0.13 to 9.5 microCi/cc. The in vivo, in vitro correlation of {sup 131}I concentrations in the urine was also good (r = 0.98, s.e.e. = 0.677 microCi/cc). Quantitative SPECT was used to calculate the effective half-life and dosimetry of radioiodine in 12 sites of thyroid carcinoma in seven patients. SPECT was also used to determine the dosimetry of ({sup 131}I)MIBG (metaiodobenzylguanidine) in two patients with carcinoid, two with neuroblastoma, and one with pheochromocytoma. The radiation dose for thyroid carcinoma metastases varied between 6.3 and 276.9 rad/mCi. The dose from MIBG varied between 13.4 and 57.8 rad/mCi. These results indicate the validity of quantitative SPECT for in vivo measurement of {sup 131}I and the need to measure the concentration of {sup 131}I in individual human tumor sites.

  8. Electron specific absorbed fractions for the adult male and female ICRP/ICRU reference computational phantoms

    NASA Astrophysics Data System (ADS)

    Zankl, Maria; Schlattl, Helmut; Petoussi-Henss, Nina; Hoeschen, Christoph

    2012-07-01

    The calculation of radiation dose from internally incorporated radionuclides is based on so-called absorbed fractions (AFs) and specific absorbed fractions (SAFs). SAFs for monoenergetic electrons were calculated for 63 source regions and 67 target regions using the new male and female adult reference computational phantoms adopted by the ICRP and ICRU and the Monte Carlo radiation transport programme package EGSnrc. The SAF values for electrons are opposed to the simplifying assumptions of ICRP Publication 30. The previously applied assumption of electrons being fully absorbed in the source organ itself is not always true at electron energies above approximately 300-500 keV. High-energy electrons have the ability to leave the source organ and, consequently, the electron SAFs for neighbouring organs can reach the same magnitude as those for photons for electron energies above 1 MeV. The reciprocity principle known for photons can be extended to electron SAFs as well, thus making cross-fire electron SAFs mass-independent. To quantify the impact of the improved electron dosimetry in comparison to the dosimetry using the simple assumptions of ICRP Publication 30, absorbed doses per administered activity of three radiopharmaceuticals were evaluated with and without explicit electron transport. The organ absorbed doses per administered activity for the two evaluation methods agree within 2%-3% for most organs for radionuclides with decay spectra having electron energies below a few hundred keV and within approximately 20% if higher electron energies are involved. An important exception is the urinary bladder wall, where the dose is overestimated by 60-150% using the simplified ICRP 30 approach for the radiopharmaceuticals of this study.

  9. Large scale study on the variation of RF energy absorption in the head & brain regions of adults and children and evaluation of the SAM phantom conservativeness

    NASA Astrophysics Data System (ADS)

    Keshvari, J.; Kivento, M.; Christ, A.; Bit-Babik, G.

    2016-04-01

    This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases.

  10. Large scale study on the variation of RF energy absorption in the head & brain regions of adults and children and evaluation of the SAM phantom conservativeness.

    PubMed

    Keshvari, J; Kivento, M; Christ, A; Bit-Babik, G

    2016-04-21

    This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases.

  11. Astronaut's organ doses inferred from measurements in a human phantom outside the international space station.

    PubMed

    Reitz, Guenther; Berger, Thomas; Bilski, Pawel; Facius, Rainer; Hajek, Michael; Petrov, Vladislav; Puchalska, Monika; Zhou, Dazhuang; Bossler, Johannes; Akatov, Yury; Shurshakov, Vyacheslav; Olko, Pawel; Ptaszkiewicz, Marta; Bergmann, Robert; Fugger, Manfred; Vana, Norbert; Beaujean, Rudolf; Burmeister, Soenke; Bartlett, David; Hager, Luke; Pálfalvi, József; Szabó, Julianna; O'Sullivan, Denis; Kitamura, Hisashi; Uchihori, Yukio; Yasuda, Nakahiro; Nagamatsu, Aiko; Tawara, Hiroko; Benton, Eric; Gaza, Ramona; McKeever, Stephen; Sawakuchi, Gabriel; Yukihara, Eduardo; Cucinotta, Francis; Semones, Edward; Zapp, Neal; Miller, Jack; Dettmann, Jan

    2009-02-01

    Space radiation hazards are recognized as a key concern for human space flight. For long-term interplanetary missions, they constitute a potentially limiting factor since current protection limits for low-Earth orbit missions may be approached or even exceeded. In such a situation, an accurate risk assessment requires knowledge of equivalent doses in critical radiosensitive organs rather than only skin doses or ambient doses from area monitoring. To achieve this, the MATROSHKA experiment uses a human phantom torso equipped with dedicated detector systems. We measured for the first time the doses from the diverse components of ionizing space radiation at the surface and at different locations inside the phantom positioned outside the International Space Station, thereby simulating an extravehicular activity of an astronaut. The relationships between the skin and organ absorbed doses obtained in such an exposure show a steep gradient between the doses in the uppermost layer of the skin and the deep organs with a ratio close to 20. This decrease due to the body self-shielding and a concomitant increase of the radiation quality factor by 1.7 highlight the complexities of an adequate dosimetry of space radiation. The depth-dose distributions established by MATROSHKA serve as benchmarks for space radiation models and radiation transport calculations that are needed for mission planning.

  12. Construction of hybrid Chinese reference adult phantoms and estimation of dose conversion coefficients for muons.

    PubMed

    Dong, Liang; Li, Taosheng; Liu, Chunyu

    2015-04-01

    A set of fluence-to-effective dose conversion coefficients of external exposure to muons were investigated for Chinese hybrid phantom references, which include both male and female. Both polygon meshes and Non-Uniform Rational B-Spline (NURBS) surfaces were used to descried the boundary of the organs and tissues in these phantoms. The 3D-DOCTOR and Rhinoceros software were used to polygonise the colour slice images and generate the NURBS surfaces, respectively. The voxelisation is completed using the BINVOX software and the assembly finished by using MATLAB codes. The voxel resolutions were selected to be 0.22 × 0.22 × 0.22 cm(3) and 0.2 × 0.2 × 0.2 cm(3) for male and female phantoms, respectively. All parts of the final phantoms were matched to their reference organ masses within a tolerance of ±5%. The conversion coefficients for negative and positive muons were calculated with the FLUKA transport code. There were 21 external monoenergetic beams ranging from 0.01 GeV to 100 TeV in 5 different geometrical conditions of irradiation.

  13. Red bone marrow dose calculations in radiotherapy of prostate cancer based on the updated VCH adult male phantom

    NASA Astrophysics Data System (ADS)

    Ai, Jinqin; Xie, Tianwu; Sun, Wenjuan; Liu, Qian

    2014-04-01

    Red bone marrow (RBM) is an important dose-limiting tissue that has high radiosensitivity but is difficult to identify on clinical medical images. In this study, we investigated dose distribution in RBM for prostate cancer radiotherapy. Four suborgans were identified in the skeleton of the visible Chinese human phantom: cortical bone (CB), trabecular bone (TB), RBM, and yellow bone marrow (YBM). Dose distributions in the phantom were evaluated by the Monte Carlo method. When the left os coxae was taken as the organ-at-risk (OAR), the difference in absorbed dose between RBM and each CB and TB was up to 20%, but was much less (≤3.1%) between RBM and YBM. When the left os coxae and entire bone were both taken as OARs, RBM dose also increased with increasing planning target volume size. The results indicate the validity of using dose to homogeneous bone marrow mixture for estimating dose to RBM when RBM is not available in computational phantoms. In addition, the human skeletal system developed in this study provides a model for considering RBM dose in radiotherapy planning.

  14. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit.

    PubMed

    Mahdipour, Seyed Ali; Mowlavi, Ali Asghar

    2016-01-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth-dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8MeV proton, 190.1MeV alpha, and 1060MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam׳s Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  15. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit

    SciTech Connect

    Mahdipour, Seyed Ali; Mowlavi, Ali Asghar

    2016-07-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth−dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8 MeV proton, 190.1 MeV alpha, and 1060 MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam's Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  16. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    NASA Astrophysics Data System (ADS)

    Könik, Arda; Connolly, Caitlin M.; Johnson, Karen L.; Dasari, Paul; Segars, Paul W.; Pretorius, P. H.; Lindsay, Clifford; Dey, Joyoni; King, Michael A.

    2014-07-01

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  17. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging.

    PubMed

    Könik, Arda; Connolly, Caitlin M; Johnson, Karen L; Dasari, Paul; Segars, Paul W; Pretorius, P H; Lindsay, Clifford; Dey, Joyoni; King, Michael A

    2014-07-21

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  18. Realistic reference adult and paediatric phantom series for internal and external dosimetry.

    PubMed

    Stabin, M G; Emmons, M A; Segars, W P; Fernald, M J

    2012-03-01

    A new generation of realistic, image-based anthropomorphic phantoms has been developed based on the reference masses and organ definitions given in the International Commission on Radiological Protection Publication 89. Specific absorbed fractions for internal radiation sources have been calculated for photon and electron sources for many body organs. Values are similar to those from the previous generation of 'stylized' (mathematical equation-based) models, but some differences are seen, particularly at low particle or photon energies, due to the more realistic organ geometries, with organs generally being closer together, and with some touching and overlapping. Extension of this work, to use these phantoms in Monte Carlo radiation transport simulation codes with external radiation sources, is an important area of investigation that should be undertaken.

  19. A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms.

    PubMed

    Krueger, Diane; Libber, Jessie; Sanfilippo, Jennifer; Yu, Hui Jing; Horvath, Blaine; Miller, Colin G; Binkley, Neil

    2016-01-01

    New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good

  20. Automatic exposure control in pediatric and adult multidetector CT examinations: A phantom study on dose reduction and image quality

    SciTech Connect

    Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

    2008-10-15

    The aim of this study was to assess the potential of a modern x,y,z modulation-based automatic exposure control system (AEC) for dose reduction in pediatric and adult multidetector CT (MDCT) imaging and evaluate the quality of the images obtained. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-, 5-, 10-year old child, and adult were scanned with a MDCT scanner, equipped with a modern AEC system. Dose reduction (%DR) was calculated as the percentage difference of the mean modulated and the preset tube current-time product that is prescribed for standard head and body scan protocols. The effect of the tube potential and the orientation of the topogram acquisition on dose reduction were assessed. Image quality was evaluated on the basis of image noise and signal to noise ratio (SNR). The dose reduction values achieved in pediatric phantoms were remarkably lower than those achieved for the adult. The efficiency of the AEC is decreased at 80 kVp compared to higher tube potentials and for helical scans following an anterior posterior (AP-AEC) compared to a lateral (LAT-AEC) topogram acquisition. In AP-AEC scans, the dose reduction ranged between 4.7 and 34.7% for neonate, 15.4 and 30.9% for 1 year old, 3.1 and 26.7% for 5 years old, 1.2 and 58.7% for 10 years old, and 15.5 and 57.4% for adult. In LAT-AEC scans, the corresponding dose reduction ranged between 11.0 and 36.5%, 27.2 and 35.7%, 11.3 and 35.6%, 0.3 and 67.0%, and 15.0 and 61.7%, respectively. AP-AEC scans resulted in a 17.1% and 19.7% dose increase in the thorax of neonate and the pelvis of the 10-year old phantom, respectively. The variation in the measured noise among images obtained along the scanning z axis was lower in AEC activated compared to fixed milliamperes scans. However, image noise was significantly increased (P<.001) and SNR significantly decreased (P<.001) in most AEC activated compared to fixed milliamperes scans. In conclusion, AEC resulted in a (i

  1. Design of a phantom equivalent to measure bone-fluorine in a human's hand via delayed neutron activation analysis.

    PubMed

    Mostafaei, F; McNeill, F E; Chettle, D R; Prestwich, W V; Inskip, M

    2013-05-01

    Fluorine is an element that can be either beneficial or harmful, depending on the total amount accumulated in the teeth or bones. In our laboratory, we have developed a non-invasive technique for the in vivo measurement of fluoride in bone using neutron activation analysis and performed the first pilot human study. Fluoride in humans is quantified by comparing the γ-ray signal from a person to the γ-ray signal obtained from appropriate anthropomorphic calibration phantoms. An identified problem with existing fluoride phantoms is contamination with aluminum. Aluminum creates an interfering γ-ray signal which, although it can be subtracted out, increases the uncertainty in the measurement and worsens the detection limit. This paper outlines a series of studies undertaken to develop a better calibration phantom for fluorine measurement, which does not have aluminum contamination.

  2. Wireless Performance of a Fully Passive Neurorecording Microsystem Embedded in Dispersive Human Head Phantom

    NASA Technical Reports Server (NTRS)

    Schwerdt, Helen N.; Chae, Junseok; Miranda, Felix A.

    2012-01-01

    This paper reports the wireless performance of a biocompatible fully passive microsystem implanted in phantom media simulating the dispersive dielectric properties of the human head, for potential application in recording cortical neuropotentials. Fully passive wireless operation is achieved by means of backscattering electromagnetic (EM) waves carrying 3rd order harmonic mixing products (2f(sub 0) plus or minus f(sub m)=4.4-4.9 GHZ) containing targeted neuropotential signals (fm approximately equal to 1-1000 Hz). The microsystem is enclosed in 4 micrometer thick parylene-C for biocompatibility and has a footprint of 4 millimeters x 12 millimeters x 500 micrometers. Preliminary testing of the microsystem implanted in the lossy biological simulating media results in signal-to-noise ratio's (SNR) near 22 (SNR approximately equal to 38 in free space) for millivolt level neuropotentials, demonstrating the potential for fully passive wireless microsystems in implantable medical applications.

  3. New conversion factors between human and automatic readouts of the CDMAM phantom for CR systems

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Homolka, Peter; Osanna-Elliot, Angelika; Kaar, Marcus; Semtrus, Friedrich; Figl, Michael

    2016-03-01

    Mammography screenings demand for profound image quality (IQ) assessment to guarantee their screening success. The European protocol for the quality control of the physical and technical aspects of mammography screening (EPQCM) suggests a contrast detail phantom such as the CDMAM phantom to evaluate IQ. For automatic evaluation a software is provided by the EUREF. As human and automatic readouts differ systematically conversion factors were published by the official reference organisation (EUREF). As we experienced a significant difference for these factors for Computed Radiography (CR) systems we developed an objectifying analysis software which presents the cells including the gold disks randomly in thickness and rotation. This allows to overcome the problem of an inevitable learning effect where observers know the position of the disks in advance. Applying this software, 45 computed radiography (CR) systems were evaluated and the conversion factors between human and automatic readout determined. The resulting conversion factors were compared with the ones resulting from the two methods published by EUREF. We found our conversion factors to be substantially lower than those suggested by EUREF, in particular 1.21 compared to 1.42 (EUREF EU method) and 1.62 (EUREF UK method) for 0.1 mm, and 1.40 compared to 1.73 (EUREF EU) and 1.83 (EUREF UK) for 0.25 mm disc diameter, respectively. This can result in a dose increase of up to 90% using either of these factors to adjust patient dose in order to fulfill image quality requirements. This suggests the need of an agreement on their proper application and limits the validity of the assessment methods. Therefore, we want to stress the need for clear criteria for CR systems based on appropriate studies.

  4. Numerical Analysis of Organ Doses Delivered During Computed Tomography Examinations Using Japanese Adult Phantoms with the WAZA-ARI Dosimetry System.

    PubMed

    Takahashi, Fumiaki; Sato, Kaoru; Endo, Akira; Ono, Koji; Ban, Nobuhiko; Hasegawa, Takayuki; Katsunuma, Yasushi; Yoshitake, Takayasu; Kai, Michiaki

    2015-08-01

    A dosimetry system for computed tomography (CT) examinations, named WAZA-ARI, is being developed to accurately assess radiation doses to patients in Japan. For dose calculations in WAZA-ARI, organ doses were numerically analyzed using average adult Japanese male (JM) and female (JF) phantoms with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the photon energy distribution of emitted photons and dose profiles on the table for some multi-detector row CT (MDCT) devices. Numerical analyses using a source model in PHITS could specifically take into account emissions of x rays from the tube to the table with attenuation of photons through a beam-shaping filter for each MDCT device based on the experiment results. The source model was validated by measuring the CT dose index (CTDI). Numerical analyses with PHITS revealed a concordance of organ doses with body sizes of the JM and JF phantoms. The organ doses in the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculations in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model (THRA1 phantom). The results imply that numerical analyses using the Japanese phantoms and specified source models can give reasonable estimates of dose for MDCT devices for typical Japanese adults.

  5. Generation of a suite of 3D computer-generated breast phantoms from a limited set of human subject data

    SciTech Connect

    Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T. III

    2013-04-15

    Purpose: The authors previously reported on a three-dimensional computer-generated breast phantom, based on empirical human image data, including a realistic finite-element based compression model that was capable of simulating multimodality imaging data. The computerized breast phantoms are a hybrid of two phantom generation techniques, combining empirical breast CT (bCT) data with flexible computer graphics techniques. However, to date, these phantoms have been based on single human subjects. In this paper, the authors report on a new method to generate multiple phantoms, simulating additional subjects from the limited set of original dedicated breast CT data. The authors developed an image morphing technique to construct new phantoms by gradually transitioning between two human subject datasets, with the potential to generate hundreds of additional pseudoindependent phantoms from the limited bCT cases. The authors conducted a preliminary subjective assessment with a limited number of observers (n= 4) to illustrate how realistic the simulated images generated with the pseudoindependent phantoms appeared. Methods: Several mesh-based geometric transformations were developed to generate distorted breast datasets from the original human subject data. Segmented bCT data from two different human subjects were used as the 'base' and 'target' for morphing. Several combinations of transformations were applied to morph between the 'base' and 'target' datasets such as changing the breast shape, rotating the glandular data, and changing the distribution of the glandular tissue. Following the morphing, regions of skin and fat were assigned to the morphed dataset in order to appropriately assign mechanical properties during the compression simulation. The resulting morphed breast was compressed using a finite element algorithm and simulated mammograms were generated using techniques described previously. Sixty-two simulated mammograms, generated from morphing three human

  6. Arts & Humanities in Adult Education.

    ERIC Educational Resources Information Center

    Word's Worth: A Quarterly Newsletter of the Lifelong Learning Network, 1998

    1998-01-01

    This issue of a quarterly newsletter on lifelong learning focuses on the theme of the arts and humanities in adult literacy education. The following articles are included: (1) "In Defense of a Practical Education" (Earl Shorris); (2) "From the Program Director" (Elizabeth Bryant McCrary); (3) "Vermont Council on the Humanities: Book Discussion…

  7. Development of a new forming process to fabricate a wide range of phantoms that highly match the acoustical properties of human bone

    NASA Astrophysics Data System (ADS)

    Wydra, Adrian

    In the various stages of developing diagnostic and therapeutic equipment, the use of phantoms can play a very important role in improving the process, and help with implementation, testing and calibrations. However, devices that use different physical factors, such as MRI, Ultrasound, CT Scan, etc. require the phantom to be made with different physical properties. This thesis deals with ultrasound and it introduces a novel composite material and a new forming process to fabricate a wide range of phantoms that highly match the acoustical properties of human bones. In contrast to ex vivo tissues, the proposed material can maintain its custom designed physical and acoustical properties unchanged for long periods of time. As results, the author introduces examples of already manufactured ultrasound phantoms (i.e. human head phantom) and a novel method of simultaneous measurements of skull thickness and its sound velocity using a set of skull bone phantoms.

  8. Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study.

    PubMed

    Thor, Daniel; Brismar, Torkel B; Fischer, Michael A

    2015-09-01

    To evaluate the potential of low tube voltage dual source (DS) single energy (SE) and dual energy (DE) computed tomography (CT) to reduce contrast media (CM) dose in adult abdominal examinations of various sizes while maintaining soft tissue and iodine contrast-to-noise ratio (CNR). Four abdominal phantoms simulating a body mass index of 16 to 35 kg/m(2) with four inserted syringes of 0, 2, 4, and 8 mgI/ml CM were scanned using a 64-slice DS-CT scanner. Six imaging protocols were used; one single source (SS) reference protocol (120 kV, 180 reference mAs), four low kV SE protocols (70 and 80 kV using both SS and DS), and one DE protocol at 80/140 kV. Potential CM reduction with unchanged CNRs relative to the 120 kV protocol was calculated along with the corresponding increase in radiation dose. The potential contrast media reductions were determined to be approximately 53% for DS 70 kV, 51% for SS 70 kV, 44% for DS 80 kV, 40% for SS 80 kV, and 20% for DE (all differences were significant, P < 0.05). Constant CNR could be achieved by using DS 70 kV for small to medium phantom sizes (16-26 kg/m(2)) and for all sizes (16-35 kg/m(2)) when using DS 80 kV and DE. Corresponding radiation doses increased by 60%-107%, 23%-83%, and 6%-12%, respectively. DS single energy CT can be used to reduce CM dose by 44%-53% with maintained CNR in adult abdominal examinations at the cost of an increased radiation dose. DS dual-energy CT allows reduction of CM dose by 20% at similar radiation dose as compared to a standard 120 kV single source.

  9. Phantom Pain

    MedlinePlus

    ... horizon Newer approaches to relieve phantom pain include virtual reality goggles. The computer program for the goggles mirrors ... Pain Medicine. In press. Accessed Sept. 15, 2014. Virtual reality therapies for phantom limb pain. European Journal of ...

  10. The GSF family of voxel phantoms

    NASA Astrophysics Data System (ADS)

    Petoussi-Henss, Nina; Zankl, Maria; Fill, Ute; Regulla, Dieter

    2002-01-01

    Voxel phantoms are human models based on computed tomographic or magnetic resonance images obtained from high-resolution scans of a single individual. They consist of a huge number of volume elements (voxels) and are at the moment the most precise representation of the human anatomy. The purpose of this paper is to introduce the GSF voxel phantoms, with emphasis on the new ones and highlight their characteristics and limitations. The GSF voxel family includes at the moment two paediatric and five adult phantoms of both sexes, different ages and stature and several others are under construction. Two phantoms made of physical calibration phantoms are also available to be used for validation purposes. The GSF voxel phantoms tend to cover persons of individual anatomy and were developed to be used for numerical dosimetry of radiation transport but other applications are also possible. Examples of applications in patient dosimetry in diagnostic radiology and in nuclear medicine as well as for whole-body irradiations from idealized external exposures are given and discussed.

  11. Inclusion of thin target and source regions in alimentary and respiratory tract systems of mesh-type ICRP adult reference phantoms

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.

  12. Inclusion of thin target and source regions in alimentary and respiratory tract systems of mesh-type ICRP adult reference phantoms.

    PubMed

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

    2017-03-21

    It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.

  13. The contemporary JAEA Japanese voxel phantoms.

    PubMed

    Sato, Kaoru; Takahashi, Fumiaki

    2012-03-01

    Average adult Japanese male (JM-103 phantom) and female (JF-103 phantom) voxel (volume pixel) phantoms were newly constructed by modifying the JM and JF phantoms previously developed at Japan Atomic Energy Agency. The JM-103 and JF-103 have average characteristics with respect to organ masses and body sizes. Their tissue segmentations were based on International Commission on Radiological Protection (ICRP) Publication 103. The anatomical and dosimetric characteristics of JM-103 and JF-103 were compared with those of ICRP adult reference male (AM phantom) and female (AF phantoms) phantoms. This study discusses their anatomical and dosimetric characteristics, and applications to the dose assessment of the atomic bomb survivors.

  14. Idiopathic generalised epilepsy in adults manifested by phantom absences, generalised tonic-clonic seizures, and frequent absence status

    PubMed Central

    Panayiotopoulos, C; Koutroumanidis, M; Giannakodimos, S; Agathonikou, A

    1997-01-01

    OBJECTIVES—To describe the clinical and EEG features of adult patients with very mild absences, late onset generalised tonic clonic seizures, and frequent absence status.
METHODS—Patients were referrals to a clinic for epilepsies. They all had clinical assessment and EEG, video EEG, or both for documentation of absences.
RESULTS—Of 86 adults with idiopathic generalised epilepsies and EEG/video-EEG documented absences, 13 patients showed similar clinico-EEG features with: (a) "phantom absences" consisting of mild ictal impairment of cognition associated with brief (3-4 s), generalised 3-4 Hz spike/multiple spike and slow wave discharges; (b) infrequent, mainly late onset, generalised tonic clonic seizures, and (c), absence status which occurred in six of them either in isolation or terminating with generalised tonic clonic seizures. None of the patients had myoclonic jerks or photosensitivity. Two patients were father and daughter and another patient had a family history of infrequent generalised tonic clonic seizures.
CONCLUSION—It seems that this is an idiopathic generalised epilepsy syndrome in adults which has not been previously recognised.

 PMID:9408104

  15. Spatio-temporal anomalous diffusion imaging: results in controlled phantoms and in excised human meningiomas.

    PubMed

    Capuani, Silvia; Palombo, Marco; Gabrielli, Andrea; Orlandi, Augusto; Maraviglia, Bruno; Pastore, Francesco S

    2013-04-01

    Recently, we measured two anomalous diffusion (AD) parameters: the spatial and the temporal AD indices, called γ and α, respectively, by using spectroscopic pulse gradient field methods. We showed that γ quantifies pseudo-superdiffusion processes, while α quantifies subdiffusion processes. Here, we propose γ and α maps obtained in a controlled heterogeneous phantom, comprised of packed micro-beads in water and in excised human meningiomas. In few words, α maps represent the multi-scale spatial distribution of the disorder degree in the system, while γ maps are influenced by local internal gradients, thus highlighting the interface between compartments characterized by different magnetic susceptibility. γ maps were already obtained by means of AD stretched exponential imaging and α-type maps have been recently achieved for fixed rat brain with the aim of highlighting the fractal dimension of specific brain regions. However, to our knowledge, the maps representative of the spatial distribution of α and γ obtained on the same controlled sample and in the same excised tissue have never been compared. Moreover, we show here, for the first time, that α maps are representative of the spatial distribution of the disorder degree of the system. In a first phase, γ and α maps of controlled phantom characterized by an ordered and a disordered rearrangement of packed micro-beads of different sizes in water and by different magnetic susceptibility (Δχ) between beads and water were obtained. In a second phase, we investigated excised human meningiomas of different consistency. Results reported here, obtained at 9.4T, show that α and γ maps are characterized by a different image contrast. Indeed, unlike γ maps, α maps are insensible to (Δχ) and they are sensible to the disorder degree of the microstructural rearrangement. These observations strongly suggest that AD indices α and γ reflect some additional microstructural information which cannot be obtained

  16. Conversion factors between human and automatic readouts of CDMAM phantom images of CR mammography systems

    NASA Astrophysics Data System (ADS)

    Figl, Michael; Homolka, Peter; Osanna-Elliott, Angelika; Semturs, Friedrich; Kaar, Marcus; Hummel, Johann

    2016-09-01

    In mammography screening, profound assessment of technical image quality is imperative. The European protocol for the quality control of the physical and technical aspects of mammography screening (EPQCM) suggests using an alternate fixed choice contrast-detail phantom-like CDMAM. For the evaluation of technical image quality, human or automated readouts can be used. For automatic evaluation, a software (cdcom) is provided by EUREF. If the automated readout indicates unacceptable image quality, additional human readout may be performed overriding the automated readout. As the latter systematically results in higher image quality ratings, conversion factors between both methods are regularly applied. Since most image quality issues with mammography systems arise within CR systems, an assessment restricted to CR systems with data from the Austrian Reference Center in the mammography screening program has been conducted. Forty-five CR systems were evaluated. Human readouts were performed with a randomisation software to avoid bias due to learning effects. Additional automatic evaluation allowed for the computation of conversion factors between human and automatic readouts. These factors were substantially lower compared to those suggested by EUREF, namely 1.21 compared to 1.62 (EUREF UK method) and 1.42 (EUREF EU method) for 0.1 mm, and 1.40 compared to 1.83 (EUREF UK) and 1.73 (EUREF EU) for 0.25 mm structure size, respectively. Using either of these factors to adjust patient dose in order to comply with image quality requirements results in differences in the dose increase of up to 90%. This necessitates a consensus on their proper application and limits the validity of the assessment methods. Clear criteria for CR systems based on appropriate studies should be promoted.

  17. Conversion factors between human and automatic readouts of CDMAM phantom images of CR mammography systems.

    PubMed

    Figl, Michael; Homolka, Peter; Osanna-Elliott, Angelika; Semturs, Friedrich; Kaar, Marcus; Hummel, Johann

    2016-09-21

    In mammography screening, profound assessment of technical image quality is imperative. The European protocol for the quality control of the physical and technical aspects of mammography screening (EPQCM) suggests using an alternate fixed choice contrast-detail phantom-like CDMAM. For the evaluation of technical image quality, human or automated readouts can be used. For automatic evaluation, a software (cdcom) is provided by EUREF. If the automated readout indicates unacceptable image quality, additional human readout may be performed overriding the automated readout. As the latter systematically results in higher image quality ratings, conversion factors between both methods are regularly applied. Since most image quality issues with mammography systems arise within CR systems, an assessment restricted to CR systems with data from the Austrian Reference Center in the mammography screening program has been conducted. Forty-five CR systems were evaluated. Human readouts were performed with a randomisation software to avoid bias due to learning effects. Additional automatic evaluation allowed for the computation of conversion factors between human and automatic readouts. These factors were substantially lower compared to those suggested by EUREF, namely 1.21 compared to 1.62 (EUREF UK method) and 1.42 (EUREF EU method) for 0.1 mm, and 1.40 compared to 1.83 (EUREF UK) and 1.73 (EUREF EU) for 0.25 mm structure size, respectively. Using either of these factors to adjust patient dose in order to comply with image quality requirements results in differences in the dose increase of up to 90%. This necessitates a consensus on their proper application and limits the validity of the assessment methods. Clear criteria for CR systems based on appropriate studies should be promoted.

  18. Effective dose measured with a life size human phantom in a low Earth orbit mission.

    PubMed

    Yasuda, Hiroshi

    2009-03-01

    The biggest concern about the health risk to astronauts is how large the stochastic effects (cancers and hereditary effects) of space radiation could be. The practical goal is to determine the "effective dose" precisely, which is difficult for each crew because of the complex transport processes of energetic secondary particles. The author and his colleagues thus attempted to measure an effective dose in space using a life-size human phantom torso in the STS-91 Shuttle-Mir mission, which flew at nearly the same orbit as that of the International Space Station (ISS). The effective dose for about 10-days flight was 4.1 mSv, which is about 90% of the dose equivalent (H) at the skin; the lowest H values were seen in deep, radiation-sensitive organs/tissues such as the bone marrow and colon. Succeeding measurements and model calculations show that the organ dose equivalents and effective dose in the low Earth orbit mission are highly consistent, despite the different dosimetry methodologies used to determine them.

  19. Development of anatomically realistic numerical breast phantoms with accurate dielectric properties for modeling microwave interactions with the human breast.

    PubMed

    Zastrow, Earl; Davis, Shakti K; Lazebnik, Mariya; Kelcz, Frederick; Van Veen, Barry D; Hagness, Susan C

    2008-12-01

    Computational electromagnetics models of microwave interactions with the human breast serve as an invaluable tool for exploring the feasibility of new technologies and improving design concepts related to microwave breast cancer detection and treatment. In this paper, we report the development of a collection of anatomically realistic 3-D numerical breast phantoms of varying shape, size, and radiographic density which can readily be used in finite-difference time-domain computational electromagnetics models. The phantoms are derived from T1-weighted MRIs of prone patients. Each MRI is transformed into a uniform grid of dielectric properties using several steps. First, the structure of each phantom is identified by applying image processing techniques to the MRI. Next, the voxel intensities of the MRI are converted to frequency-dependent and tissue-dependent dielectric properties of normal breast tissues via a piecewise-linear map. The dielectric properties of normal breast tissue are taken from the recently completed large-scale experimental study of normal breast tissue dielectric properties conducted by the Universities of Wisconsin and Calgary. The comprehensive collection of numerical phantoms is made available to the scientific community through an online repository.

  20. Development of Anatomically Realistic Numerical Breast Phantoms with Accurate Dielectric Properties for Modeling Microwave Interactions with the Human Breast

    PubMed Central

    Zastrow, Earl; Davis, Shakti K.; Lazebnik, Mariya; Kelcz, Frederick; Van Veen, Barry D.; Hagness, Susan C.

    2008-01-01

    Computational electromagnetics models of microwave interactions with the human breast serve as an invaluable tool for exploring the feasibility of new technologies and improving design concepts related to microwave breast cancer detection and treatment. In this paper we report the development of a collection of anatomically realistic 3D numerical breast phantoms of varying shape, size, and radiographic density which can be readily used in FDTD computational electromagnetics models. The phantoms are derived from T1-weighted magnetic resonance images (MRIs) of prone patients. Each MRI is transformed into a uniform grid of dielectric properties using several steps. First, the structure of each phantom is identified by applying image processing techniques to the MRI. Next, the voxel intensities of the MRI are converted to frequency-dependent and tissue-dependent dielectric properties of normal breast tissues via a piecewise-linear map. The dielectric properties of normal breast tissue are taken from the recently completed large-scale experimental study of normal breast tissue dielectric properties conducted by the Universities of Wisconsin and Calgary. The comprehensive collection of numerical phantoms is made available to the scientific community through an online repository. PMID:19126460

  1. Effect of leaded glasses and thyroid shielding on cone beam CT radiation dose in an adult female phantom.

    PubMed

    Goren, A D; Prins, R D; Dauer, L T; Quinn, B; Al-Najjar, A; Faber, R D; Patchell, G; Branets, I; Colosi, D C

    2013-01-01

    This study aims to demonstrate the effectiveness of leaded glasses in reducing the lens of eye dose and of lead thyroid collars in reducing the dose to the thyroid gland of an adult female from dental cone beam CT (CBCT). The effect of collimation on the radiation dose in head organs is also examined. Dose measurements were conducted by placing optically stimulated luminescent dosemeters in an anthropomorphic female phantom. Eye lens dose was measured by placing a dosemeter on the anterior surface of the phantom eye location. All exposures were performed on one commercially available dental CBCT machine, using selected collimation and exposure techniques. Each scan technique was performed without any lead shielding and then repeated with lead shielding in place. To calculate the percent reduction from lead shielding, the dose measured with lead shielding was divided by the dose measured without lead shielding. The percent reduction from collimation was calculated by comparing the dose measured with collimation to the dose measured without collimation. The dose to the internal eye for one of the scans without leaded glasses or thyroid shield was 0.450 cGy and with glasses and thyroid shield was 0.116 cGy (a 74% reduction). The reduction to the lens of the eye was from 0.396 cGy to 0.153 cGy (a 61% reduction). Without glasses or thyroid shield, the thyroid dose was 0.158 cGy; and when both glasses and shield were used, the thyroid dose was reduced to 0.091 cGy (a 42% reduction). Collimation alone reduced the dose to the brain by up to 91%, with a similar reduction in other organs. Based on these data, leaded glasses, thyroid collars and collimation minimize the dose to organs outside the field of view.

  2. Effect of leaded glasses and thyroid shielding on cone beam CT radiation dose in an adult female phantom

    PubMed Central

    Goren, AD; Prins, RD; Dauer, LT; Quinn, B; Al-Najjar, A; Faber, RD; Patchell, G; Branets, I; Colosi, DC

    2013-01-01

    Objectives: This study aims to demonstrate the effectiveness of leaded glasses in reducing the lens of eye dose and of lead thyroid collars in reducing the dose to the thyroid gland of an adult female from dental cone beam CT (CBCT). The effect of collimation on the radiation dose in head organs is also examined. Methods: Dose measurements were conducted by placing optically stimulated luminescent dosemeters in an anthropomorphic female phantom. Eye lens dose was measured by placing a dosemeter on the anterior surface of the phantom eye location. All exposures were performed on one commercially available dental CBCT machine, using selected collimation and exposure techniques. Each scan technique was performed without any lead shielding and then repeated with lead shielding in place. To calculate the percent reduction from lead shielding, the dose measured with lead shielding was divided by the dose measured without lead shielding. The percent reduction from collimation was calculated by comparing the dose measured with collimation to the dose measured without collimation. Results: The dose to the internal eye for one of the scans without leaded glasses or thyroid shield was 0.450 cGy and with glasses and thyroid shield was 0.116 cGy (a 74% reduction). The reduction to the lens of the eye was from 0.396 cGy to 0.153 cGy (a 61% reduction). Without glasses or thyroid shield, the thyroid dose was 0.158 cGy; and when both glasses and shield were used, the thyroid dose was reduced to 0.091 cGy (a 42% reduction). Conclusions: Collimation alone reduced the dose to the brain by up to 91%, with a similar reduction in other organs. Based on these data, leaded glasses, thyroid collars and collimation minimize the dose to organs outside the field of view. PMID:23412460

  3. The UF family of reference hybrid phantoms for computational radiation dosimetry.

    PubMed

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

    2010-01-21

    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. 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. The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference organ

  4. THE UF FAMILY OF REFERENCE HYBRID PHANTOMS FOR COMPUTATIONAL RADIATION DOSIMETRY

    PubMed Central

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

    2009-01-01

    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 the 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™. 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™. The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2

  5. Extension of RPI-adult male and female computational phantoms to obese patients and a Monte Carlo study of the effect on CT imaging dose

    NASA Astrophysics Data System (ADS)

    Ding, Aiping; Mille, Matthew M.; Liu, Tianyu; Caracappa, Peter F.; Xu, X. George

    2012-05-01

    Although it is known that obesity has a profound effect on x-ray computed tomography (CT) image quality and patient organ dose, quantitative data describing this relationship are not currently available. This study examines the effect of obesity on the calculated radiation dose to organs and tissues from CT using newly developed phantoms representing overweight and obese patients. These phantoms were derived from the previously developed RPI-adult male and female computational phantoms. The result was a set of ten phantoms (five males, five females) with body mass indexes ranging from 23.5 (normal body weight) to 46.4 kg m-2 (morbidly obese). The phantoms were modeled using triangular mesh geometry and include specified amounts of the subcutaneous adipose tissue and visceral adipose tissue. The mesh-based phantoms were then voxelized and defined in the Monte Carlo N-Particle Extended code to calculate organ doses from CT imaging. Chest-abdomen-pelvis scanning protocols for a GE LightSpeed 16 scanner operating at 120 and 140 kVp were considered. It was found that for the same scanner operating parameters, radiation doses to organs deep in the abdomen (e.g., colon) can be up to 59% smaller for obese individuals compared to those of normal body weight. This effect was found to be less significant for shallow organs. On the other hand, increasing the tube potential from 120 to 140 kVp for the same obese individual resulted in increased organ doses by as much as 56% for organs within the scan field (e.g., stomach) and 62% for those out of the scan field (e.g., thyroid), respectively. As higher tube currents are often used for larger patients to maintain image quality, it was of interest to quantify the associated effective dose. It was found from this study that when the mAs was doubled for the obese level-I, obese level-II and morbidly-obese phantoms, the effective dose relative to that of the normal weight phantom increased by 57%, 42% and 23%, respectively. This set

  6. Extension of RPI-adult male and female computational phantoms to obese patients and a Monte Carlo study of the effect on CT imaging dose

    PubMed Central

    Ding, Aiping; Mille, Matthew M; Liu, Tianyu; Caracappa, Peter F; Xu, X George

    2012-01-01

    Although it is known that obesity has a profound effect on x-ray computed tomography (CT) image quality and patient organ dose, quantitative data describing this relationship are not currently available. This study examines the effect of obesity on the calculated radiation dose to organs and tissues from CT using newly developed phantoms representing overweight and obese patients. These phantoms were derived from the previously developed RPI-adult male and female computational phantoms. The result was a set of ten phantoms (five males, five females) with body mass indexes ranging from 23.5 (normal body weight) to 46.4 kg m−2 (morbidly obese). The phantoms were modeled using triangular mesh geometry and include specified amounts of the subcutaneous adipose tissue and visceral adipose tissue. The mesh-based phantoms were then voxelized and defined in the Monte Carlo N-Particle Extended code to calculate organ doses from CT imaging. Chest–abdomen–pelvis scanning protocols for a GE LightSpeed 16 scanner operating at 120 and 140 kVp were considered. It was found that for the same scanner operating parameters, radiation doses to organs deep in the abdomen (e.g., colon) can be up to 59% smaller for obese individuals compared to those of normal body weight. This effect was found to be less significant for shallow organs. On the other hand, increasing the tube potential from 120 to 140 kVp for the same obese individual resulted in increased organ doses by as much as 56% for organs within the scan field (e.g., stomach) and 62% for those out of the scan field (e.g., thyroid), respectively. As higher tube currents are often used for larger patients to maintain image quality, it was of interest to quantify the associated effective dose. It was found from this study that when the mAs was doubled for the obese level-I, obese level-II and morbidly-obese phantoms, the effective dose relative to that of the normal weight phantom increased by 57%, 42% and 23%, respectively

  7. Low-tube-voltage selection for non-contrast-enhanced CT: Comparison of the radiation dose in pediatric and adult phantoms.

    PubMed

    Shimonobo, Toshiaki; Funama, Yoshinori; Utsunomiya, Daisuke; Nakaura, Takeshi; Oda, Seitaro; Kiguchi, Masao; Masuda, Takanori; Sakabe, Daisuke; Yamashita, Yasuyuki; Awai, Kazuo

    2016-01-01

    We used pediatric and adult anthropomorphic phantoms to compare the radiation dose of low- and standard tube voltage chest and abdominal non-contrast-enhanced computed tomography (CT) scans. We also discuss the optimal low tube voltage for non-contrast-enhanced CT. Using a female adult- and three differently-sized pediatric anthropomorphic phantoms we acquired chest and abdominal non-contrast-enhanced scans on a 320-multidetector CT volume scanner. The tube voltage was set at 80-, 100-, and 120 kVp. The tube current was automatically assigned on the CT scanner in response to the set image noise level. On each phantom and at each tube voltage we measured the surface and center dose using high-sensitivity metal-oxide-semiconductor field-effect transistor detectors. The mean surface dose of chest and abdominal CT scans in 5-year olds was 4.4 and 5.3 mGy at 80 kVp, 4.5 and 5.4 mGy at 100 kV, and 4.0 and 5.0 mGy at 120 kVp, respectively. These values were similar in our 3-pediatric phantoms (p > 0.05). The mean surface dose in the adult phantom increased from 14.7 to 19.4 mGy for chest- and from 18.7 to 24.8 mGy for abdominal CT as the tube voltage decreased from 120 to 80 kVp (p < 0.01). Compared to adults, the surface and center dose for pediatric patients is almost the same despite a decrease in the tube voltage and the low tube voltage technique can be used for non-contrast-enhanced chest- and abdominal scanning. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  8. Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: Results in gel phantoms

    PubMed Central

    N’Djin, William Apoutou; Burtnyk, Mathieu; Kobelevskiy, Ilya; Hadjis, Stefan; Bronskill, Michael; Chopra, Rajiv

    2012-01-01

    Purpose: The feasibility and safety of magnetic resonance imaging (MRI)-controlled transurethral ultrasound therapy were demonstrated recently in a preliminary human study in which a small subvolume of prostate tissue was treated prior to radical prostatectomy. Translation of this technology to full clinical use, however, requires the capability to generate thermal coagulation in a volume up to that of the prostate gland itself. The aim of this study was to investigate the parameters required to treat a full 3D human prostate accurately with a multi-element transurethral applicator and multiplanar MR temperature control. Methods: The approach was a combination of simulations (to select appropriate parameters) followed by experimental confirmation in tissue-mimicking phantoms. A ten-channel, MRI-compatible transurethral ultrasound therapy system was evaluated using six human prostate models (average volume: 36 cm3) obtained from the preliminary human feasibility study. Real-time multiplanar MR thermometry at 3 T was used to control the spatial heating pattern in up to nine planes simultaneously. Treatment strategies incorporated both single (4.6 or 8.1 MHz) and dual (4.6 and 14.4 MHz) frequencies, as well as maximum acoustic surface powers of 10 or 20 W cm−2. Results: Treatments at 4.6 MHz were capable of coagulating a volume equivalent to 97% of the prostate. Increasing power from 10 to 20 W cm−2 reduced treatment times by approximately 50% with full treatments taking 26 ± 3 min at a coagulation rate of 1.8 ± 0.4 cm3 min−1. A dual-frequency 4.6/14.4 MHz treatment strategy was shown to be the most effective configuration for achieving full human prostate treatment while maintaining good treatment accuracy for small treatment radii. The dual-frequency approach reduced overtreatment close to the prostate base and apex, confirming the simulations. Conclusions: This study reinforces the capability of MRI-controlled transurethral ultrasound therapy to treat

  9. Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: Results in gel phantoms.

    PubMed

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

    2012-07-01

    The feasibility and safety of magnetic resonance imaging (MRI)-controlled transurethral ultrasound therapy were demonstrated recently in a preliminary human study in which a small subvolume of prostate tissue was treated prior to radical prostatectomy. Translation of this technology to full clinical use, however, requires the capability to generate thermal coagulation in a volume up to that of the prostate gland itself. The aim of this study was to investigate the parameters required to treat a full 3D human prostate accurately with a multi-element transurethral applicator and multiplanar MR temperature control. The approach was a combination of simulations (to select appropriate parameters) followed by experimental confirmation in tissue-mimicking phantoms. A ten-channel, MRI-compatible transurethral ultrasound therapy system was evaluated using six human prostate models (average volume: 36 cm(3) ) obtained from the preliminary human feasibility study. Real-time multiplanar MR thermometry at 3 T was used to control the spatial heating pattern in up to nine planes simultaneously. Treatment strategies incorporated both single (4.6 or 8.1 MHz) and dual (4.6 and 14.4 MHz) frequencies, as well as maximum acoustic surface powers of 10 or 20 W cm(-2) . Treatments at 4.6 MHz were capable of coagulating a volume equivalent to 97% of the prostate. Increasing power from 10 to 20 W cm(-2) reduced treatment times by approximately 50% with full treatments taking 26 ± 3 min at a coagulation rate of 1.8 ± 0.4 cm(3)  min(-1) . A dual-frequency 4.6/14.4 MHz treatment strategy was shown to be the most effective configuration for achieving full human prostate treatment while maintaining good treatment accuracy for small treatment radii. The dual-frequency approach reduced overtreatment close to the prostate base and apex, confirming the simulations. This study reinforces the capability of MRI-controlled transurethral ultrasound therapy to treat full prostate volumes in a

  10. Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: results in gel phantoms.

    PubMed

    N'djin, William Apoutou; Burtnyk, Mathieu; Kobelevskiy, Ilya; Hadjis, Stefan; Bronskill, Michael; Chopra, Rajiv

    2012-07-01

    The feasibility and safety of magnetic resonance imaging (MRI)-controlled transurethral ultrasound therapy were demonstrated recently in a preliminary human study in which a small subvolume of prostate tissue was treated prior to radical prostatectomy. Translation of this technology to full clinical use, however, requires the capability to generate thermal coagulation in a volume up to that of the prostate gland itself. The aim of this study was to investigate the parameters required to treat a full 3D human prostate accurately with a multi-element transurethral applicator and multiplanar MR temperature control. The approach was a combination of simulations (to select appropriate parameters) followed by experimental confirmation in tissue-mimicking phantoms. A ten-channel, MRI-compatible transurethral ultrasound therapy system was evaluated using six human prostate models (average volume: 36 cm(3)) obtained from the preliminary human feasibility study. Real-time multiplanar MR thermometry at 3 T was used to control the spatial heating pattern in up to nine planes simultaneously. Treatment strategies incorporated both single (4.6 or 8.1 MHz) and dual (4.6 and 14.4 MHz) frequencies, as well as maximum acoustic surface powers of 10 or 20 W cm(-2). Treatments at 4.6 MHz were capable of coagulating a volume equivalent to 97% of the prostate. Increasing power from 10 to 20 W cm(-2) reduced treatment times by approximately 50% with full treatments taking 26 ± 3 min at a coagulation rate of 1.8 ± 0.4 cm(3) min(-1). A dual-frequency 4.6∕14.4 MHz treatment strategy was shown to be the most effective configuration for achieving full human prostate treatment while maintaining good treatment accuracy for small treatment radii. The dual-frequency approach reduced overtreatment close to the prostate base and apex, confirming the simulations. This study reinforces the capability of MRI-controlled transurethral ultrasound therapy to treat full prostate volumes in a short

  11. COMPARISON OF COMPUTATIONAL PHANTOMS AND INVESTIGATION OF THE EFFECT OF BIODISTRIBUTION ON ACTIVITY ESTIMATIONS.

    PubMed

    Cartemo, Petty; Nilsson, Jenny; Isaksson, Mats; Nordlund, Anders

    2016-11-01

    A comparison was made between two computational phantoms, modelled from the unified phantom UPh-08 T, for whole-body counting applications. One of these was further compared with the International Commission on Radiological Protection reference adult male computational phantom. The simulations that were performed for the comparison of all three voxel phantoms use various distributions of (60)Co. The two voxel phantoms of the UPh-08 T showed good agreement, despite different methods of phantom modelling. Also, effects on efficiency of the inhomogeneous distribution of a radionuclide in the computational UPh-08 T phantom were studied, using the realistic biodistribution of (140)La. The results show that the activity estimation of radionuclides, which are inhomogeneously distributed in the human body, will be in error if a homogeneous distribution is assumed for the calibration of whole-body counting systems. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

    SciTech Connect

    Segars, P.

    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.

  13. Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study

    SciTech Connect

    Thor, Daniel; Brismar, Torkel B. Fischer, Michael A.

    2015-09-15

    Purpose: To evaluate the potential of low tube voltage dual source (DS) single energy (SE) and dual energy (DE) computed tomography (CT) to reduce contrast media (CM) dose in adult abdominal examinations of various sizes while maintaining soft tissue and iodine contrast-to-noise ratio (CNR). Methods: Four abdominal phantoms simulating a body mass index of 16 to 35 kg/m{sup 2} with four inserted syringes of 0, 2, 4, and 8 mgI/ml CM were scanned using a 64-slice DS-CT scanner. Six imaging protocols were used; one single source (SS) reference protocol (120 kV, 180 reference mAs), four low kV SE protocols (70 and 80 kV using both SS and DS), and one DE protocol at 80/140 kV. Potential CM reduction with unchanged CNRs relative to the 120 kV protocol was calculated along with the corresponding increase in radiation dose. Results: The potential contrast media reductions were determined to be approximately 53% for DS 70 kV, 51% for SS 70 kV, 44% for DS 80 kV, 40% for SS 80 kV, and 20% for DE (all differences were significant, P < 0.05). Constant CNR could be achieved by using DS 70 kV for small to medium phantom sizes (16–26 kg/m{sup 2}) and for all sizes (16–35 kg/m{sup 2}) when using DS 80 kV and DE. Corresponding radiation doses increased by 60%–107%, 23%–83%, and 6%–12%, respectively. Conclusions: DS single energy CT can be used to reduce CM dose by 44%–53% with maintained CNR in adult abdominal examinations at the cost of an increased radiation dose. DS dual-energy CT allows reduction of CM dose by 20% at similar radiation dose as compared to a standard 120 kV single source.

  14. Organ doses, effective doses, and risk indices in adult CT: Comparison of four types of reference phantoms across different examination protocols

    SciTech Connect

    Zhang Yakun; Li Xiang; Paul Segars, W.; Samei, Ehsan

    2012-06-15

    Purpose: Radiation exposure from computed tomography (CT) to the public has increased the concern among radiation protection professionals. Being able to accurately assess the radiation dose patients receive during CT procedures is a crucial step in the management of CT dose. Currently, various computational anthropomorphic phantoms are used to assess radiation dose by different research groups. It is desirable to better understand how the dose results are affected by different choices of phantoms. In this study, the authors assessed the uncertainties in CT dose and risk estimation associated with different types of computational phantoms for a selected group of representative CT protocols. Methods: Routinely used CT examinations were categorized into ten body and three neurological examination categories. Organ doses, effective doses, risk indices, and conversion coefficients to effective dose and risk index (k and q factors, respectively) were estimated for these examinations for a clinical CT system (LightSpeed VCT, GE Healthcare). Four methods were used, each employing a different type of reference phantoms. The first and second methods employed a Monte Carlo program previously developed and validated in our laboratory. In the first method, the reference male and female extended cardiac-torso (XCAT) phantoms were used, which were initially created from the Visible Human data and later adjusted to match organ masses defined in ICRP publication 89. In the second method, the reference male and female phantoms described in ICRP publication 110 were used, which were initially developed from tomographic data of two patients and later modified to match ICRP 89 organ masses. The third method employed a commercial dosimetry spreadsheet (ImPACT group, London, England) with its own hermaphrodite stylized phantom. In the fourth method, another widely used dosimetry spreadsheet (CT-Expo, Medizinische Hochschule, Hannover, Germany) was employed together with its associated

  15. Organ doses, effective doses, and risk indices in adult CT: Comparison of four types of reference phantoms across different examination protocols

    PubMed Central

    Zhang, Yakun; Li, Xiang; Paul Segars, W.; Samei, Ehsan

    2012-01-01

    Purpose: Radiation exposure from computed tomography (CT) to the public has increased the concern among radiation protection professionals. Being able to accurately assess the radiation dose patients receive during CT procedures is a crucial step in the management of CT dose. Currently, various computational anthropomorphic phantoms are used to assess radiation dose by different research groups. It is desirable to better understand how the dose results are affected by different choices of phantoms. In this study, the authors assessed the uncertainties in CT dose and risk estimation associated with different types of computational phantoms for a selected group of representative CT protocols. Methods: Routinely used CT examinations were categorized into ten body and three neurological examination categories. Organ doses, effective doses, risk indices, and conversion coefficients to effective dose and risk index (k and q factors, respectively) were estimated for these examinations for a clinical CT system (LightSpeed VCT, GE Healthcare). Four methods were used, each employing a different type of reference phantoms. The first and second methods employed a Monte Carlo program previously developed and validated in our laboratory. In the first method, the reference male and female extended cardiac-torso (XCAT) phantoms were used, which were initially created from the Visible Human data and later adjusted to match organ masses defined in ICRP publication 89. In the second method, the reference male and female phantoms described in ICRP publication 110 were used, which were initially developed from tomographic data of two patients and later modified to match ICRP 89 organ masses. The third method employed a commercial dosimetry spreadsheet (ImPACT group, London, England) with its own hermaphrodite stylized phantom. In the fourth method, another widely used dosimetry spreadsheet (CT-Expo, Medizinische Hochschule, Hannover, Germany) was employed together with its associated

  16. The UF family of reference hybrid phantoms for computational radiation dosimetry

    NASA Astrophysics Data System (ADS)

    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™. 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™. The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference

  17. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    NASA Astrophysics Data System (ADS)

    Winant, Celeste D.; Aparici, Carina Mari; Zelnik, Yuval R.; Reutter, Bryan W.; Sitek, Arkadiusz; Bacharach, Stephen L.; Gullberg, Grant T.

    2012-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94Tc-methoxyisobutylisonitrile (94Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99mTc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal maximum

  18. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies

    PubMed Central

    Winant, Celeste D; Aparici, Carina Mari; Zelnik, Yuval R; Reutter, Bryan W; Sitek, Arkadiusz; Bacharach, Stephen L; Gullberg, Grant T

    2012-01-01

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic 94Tc-methoxyisobutylisonitrile (94Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K1 for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K1. For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from 94Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of 99mTc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The spatiotemporal maximum

  19. Investigation of dynamic SPECT measurements of the arterial input function in human subjects using simulation, phantom and human studies.

    PubMed

    Winant, Celeste D; Aparici, Carina Mari; Zelnik, Yuval R; Reutter, Bryan W; Sitek, Arkadiusz; Bacharach, Stephen L; Gullberg, Grant T

    2012-01-21

    Computer simulations, a phantom study and a human study were performed to determine whether a slowly rotating single-photon computed emission tomography (SPECT) system could provide accurate arterial input functions for quantification of myocardial perfusion imaging using kinetic models. The errors induced by data inconsistency associated with imaging with slow camera rotation during tracer injection were evaluated with an approach called SPECT/P (dynamic SPECT from positron emission tomography (PET)) and SPECT/D (dynamic SPECT from database of SPECT phantom projections). SPECT/P simulated SPECT-like dynamic projections using reprojections of reconstructed dynamic (94)Tc-methoxyisobutylisonitrile ((94)Tc-MIBI) PET images acquired in three human subjects (1 min infusion). This approach was used to evaluate the accuracy of estimating myocardial wash-in rate parameters K(1) for rotation speeds providing 180° of projection data every 27 or 54 s. Blood input and myocardium tissue time-activity curves (TACs) were estimated using spatiotemporal splines. These were fit to a one-compartment perfusion model to obtain wash-in rate parameters K(1). For the second method (SPECT/D), an anthropomorphic cardiac torso phantom was used to create real SPECT dynamic projection data of a tracer distribution derived from (94)Tc-MIBI PET scans in the blood pool, myocardium, liver and background. This method introduced attenuation, collimation and scatter into the modeling of dynamic SPECT projections. Both approaches were used to evaluate the accuracy of estimating myocardial wash-in parameters for rotation speeds providing 180° of projection data every 27 and 54 s. Dynamic cardiac SPECT was also performed in a human subject at rest using a hybrid SPECT/CT scanner. Dynamic measurements of (99m)Tc-tetrofosmin in the myocardium were obtained using an infusion time of 2 min. Blood input, myocardium tissue and liver TACs were estimated using the same spatiotemporal splines. The

  20. Experimental study on tissue phantoms to understand the effect of injury and suturing on human skin mechanical properties.

    PubMed

    Chanda, Arnab; Unnikrishnan, Vinu; Flynn, Zachary; Lackey, Kim

    2017-01-01

    Skin injuries are the most common type of injuries occurring in day-to-day life. A skin injury usually manifests itself in the form of a wound or a cut. While a shallow wound may heal by itself within a short time, deep wounds require surgical interventions such as suturing for timely healing. To date, suturing practices are based on a surgeon's experience and may vary widely from one situation to another. Understanding the mechanics of wound closure and suturing of the skin is crucial to improve clinical suturing practices and also to plan automated robotic surgeries. In the literature, phenomenological two-dimensional computational skin models have been developed to study the mechanics of wound closure. Additionally, the effect of skin pre-stress (due to the natural tension of the skin) on wound closure mechanics has been studied. However, in most of these analyses, idealistic two-dimensional skin geometries, materials and loads have been assumed, which are far from reality, and would clearly generate inaccurate quantitative results. In this work, for the first time, a biofidelic human skin tissue phantom was developed using a two-part silicone material. A wound was created on the phantom material and sutures were placed to close the wound. Uniaxial mechanical tests were carried out on the phantom specimens to study the effect of varying wound size, quantity, suture and pre-stress on the mechanical behavior of human skin. Also, the average mechanical behavior of the human skin surrogate was characterized using hyperelastic material models, in the presence of a wound and sutures. To date, such a robust experimental study on the effect of injury and sutures on human skin mechanics has not been attempted. The results of this novel investigation will provide important guidelines for surgical planning and validation of results from computational models in the future.

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

    PubMed

    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.

  2. Dose reduction and image quality optimizations in CT of pediatric and adult patients: phantom studies

    NASA Astrophysics Data System (ADS)

    Jeon, P.-H.; Lee, C.-L.; Kim, D.-H.; Lee, Y.-J.; Jeon, S.-S.; Kim, H.-J.

    2014-03-01

    Multi-detector computed tomography (MDCT) can be used to easily and rapidly perform numerous acquisitions, possibly leading to a marked increase in the radiation dose to individual patients. Technical options dedicated to automatically adjusting the acquisition parameters according to the patient's size are of specific interest in pediatric radiology. A constant tube potential reduction can be achieved for adults and children, while maintaining a constant detector energy fluence. To evaluate radiation dose, the weighted CT dose index (CTDIw) was calculated based on the CT dose index (CTDI) measured using an ion chamber, and image noise and image contrast were measured from a scanned image to evaluate image quality. The dose-weighted contrast-to-noise ratio (CNRD) was calculated from the radiation dose, image noise, and image contrast measured from a scanned image. The noise derivative (ND) is a quality index for dose efficiency. X-ray spectra with tube voltages ranging from 80 to 140 kVp were used to compute the average photon energy. Image contrast and the corresponding contrast-to-noise ratio (CNR) were determined for lesions of soft tissue, muscle, bone, and iodine relative to a uniform water background, as the iodine contrast increases at lower energy (i.e., k-edge of iodine is 33 keV closer to the beam energy) using mixed water-iodine contrast normalization (water 0, iodine 25, 100, 200, and 1000 HU, respectively). The proposed values correspond to high quality images and can be reduced if only high-contrast organs are assessed. The potential benefit of lowering the tube voltage is an improved CNRD, resulting in a lower radiation dose and optimization of image quality. Adjusting the tube potential in abdominal CT would be useful in current pediatric radiography, where the choice of X-ray techniques generally takes into account the size of the patient as well as the need to balance the conflicting requirements of diagnostic image quality and radiation dose

  3. Evaluation of conversion coefficients from measurable to risk quantities for external exposure over contaminated soil by use of physical human phantoms.

    PubMed

    Golikov, V; Wallström, E; Wöhni, T; Tanaka, K; Endo, S; Hoshi, M

    2007-11-01

    Conversion coefficients from measurable quantities such as air kerma free-in-air or personal dose equivalent to effective dose were determined by phantom experiments. Heterogenic anthropomorphic phantoms representing children of one and five years age, and a Rando phantom representing an adult were exposed in the open field contaminated by different levels of radiocesium in the upper soil layer, in a forest site and inside a wooden house. LiF thermoluminescent (TL) detectors were used inside the phantoms for the estimation of organ doses and effective dose. Personal dosimeters similar to those used in radiation protection for individual dose measurements were placed onto the phantom surface (chest area). The ratios of dose values in separate organs to air kerma free-in-air varied from 0.69 to 1.15 for the children phantoms, and from 0.55 to 0.94 for the adult phantom, respectively, when irradiated in the open field. Body size (weight) was found to be the most important factor influencing the values of the conversion coefficients. The differences observed can reach approximately 40% when comparing conversion factors from air kerma free-in-air to effective dose for adults and newborns. For conversion coefficients from personal dose to effective dose, these differences can reach approximately 15%. The dependences of the various conversion coefficients on body mass were quantified by regression analysis. The results were compared with those calculated for a plane mono-energetic photon source having an energy of 700 keV and being located in the ground at a depth of 0.5 g cm(-2). Calculated and measured conversion coefficients from air kerma free-in-air to effective dose agreed within 12%.

  4. Results on Dose Distributions in a Human Body from the Matroshka-R Experiment onboard the ISS Obtained with the Tissue-Equivalent Spherical Phantom

    NASA Astrophysics Data System (ADS)

    Shurshakov, Vyacheslav; Nikolaev, Igor; Kartsev, Ivan; Tolochek, Raisa; Lyagushin, Vladimir

    The tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS in Matroshka-R experiment for more than 10 years. Both passive and active space radiation detectors can be located inside the phantom and on its surface. Due to the specially chosen phantom shape and size, the chord length distributions of the detector locations are attributed to self-shielding properties of the critical organs in a human body. Originally the spherical phantom was installed in the star board crew cabin of the ISS Service Module, then in the Piers-1, MIM-2, and MIM-1 modules of the ISS Russian segment, and finally in JAXA Kibo module. Total duration of the detector exposure is more than 2000 days in 9 sessions of the space experiment. In the first phase of the experiment with the spherical phantom the dose measurements were realized with only passive detectors (thermoluminescent and solid state track detectors). The detectors are placed inside the phantom along the axes of 20 containers and on the phantom outer surface in 32 pockets of the phantom jacket. After each session the passive detectors are returned to the ground. The results obtained show the dose difference on the phantom surface as much as a factor of 2, the highest dose being usually observed close to the outer wall of the compartment, and the lowest dose being in the opposite location along the phantom diameter. However, because of the ISS module shielding properties an inverse dose distribution in a human body can be observed when the dose rate maximum is closer to the geometrical center of the module. Maximum dose rate measured in the phantom is obviously due to the action of two radiation sources, namely, galactic cosmic rays (GCR) and Earth’ radiation belts. Minimum dose rate is produced mainly by the strongly penetrating GCR particles and is mostly observed behind more than 5 g/cm2 tissue shielding. Critical organ doses, mean

  5. Simulation of photoacoustic signal production in human breast phantoms at 1064 nm

    NASA Astrophysics Data System (ADS)

    Liu, Pingyu; Kruger, Robert A.; Appledorn, C. Robert; Fang, Yuncai

    1996-04-01

    Photoacoustic signals generated by breasts irradiated with short microwave, infrared or optical pulses could be used to detect breast cancer. Since radiation at this spectrum is non-ionizing, the photoacoustic approach provides a special safety feature. The purpose of the paper is to present a means to predict photoacoustic pressure signals for different breast phantoms and irradiation conditions. The photoacoustic wave equation was derived for linear, non-viscous liquid media. The equation was solved assuming uniform acoustic properties in an infinite medium. Compressed breast phantoms were used as the objects of simulation. The spatial dependence of electromagnetic energy absorption was given by another research paper of this conference. The time dependence of the absorption was assumed to be either uniform or bell- shaped. Photoacoustic pressure signals received by transducers at different locations were calculated numerically.

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

    PubMed

    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.

  7. Improving registration robustness for image-guided liver surgery in a novel human-to-phantom data framework.

    PubMed

    Collins, Jarrod; Weis, Jared; Heiselman, Jon; Clements, Logan; Simpson, Amber; Jarnagin, Willam; Miga, Michael

    2017-02-13

    In open image-guided liver surgery (IGLS), a sparse representation of the intraoperative organ surface can be acquired to drive image-to-physical registration. We hypothesize that uncharacterized error induced by variation in the collection patterns of organ surface data limits the accuracy and robustness of IGLS registration. Clinical validation of such registration methods is challenged due to the difficulty in obtaining data representative of the true state of organ deformation. We propose a novel human-to-phantom validation framework that transforms surface collection patterns from in vivo IGLS procedures (n=13) onto a well-characterized hepatic deformation phantom for the purpose of validating surface-driven, volumetric nonrigid registration methods. An important feature of the approach is that it centers on combining workflow-realistic data acquisition and surgical deformations that are appropriate in behavior and magnitude. Using the approach, we investigate volumetric target registration error (TRE) with both current rigid IGLS and our improved nonrigid registration methods. Additionally, we introduce a spatial data resampling approach to mitigate the workflow-sensitive sampling problem. Using our human-to-phantom approach, TRE after routine rigid registration was 10.9 ± 0.6 mm with a signed closest point distance associated with residual surface fit in the range of ± 10.0 mm, highly representative of open liver resections. After applying our novel resampling strategy and improved deformation correction method, TRE was reduced by 51%, i.e. a TRE of 5.3 ± 0.5 mm. The work reported herein realizes a novel tractable approach for the validation of image-to-physical registration methods and demonstrates promising results for our correction method.

  8. Precise two-dimensional D-bar reconstructions of human chest and phantom tank via sinc-convolution algorithm.

    PubMed

    Abbasi, Mahdi; Naghsh-Nilchi, Ahmad-Reza

    2012-06-20

    Electrical Impedance Tomography (EIT) is used as a fast clinical imaging technique for monitoring the health of the human organs such as lungs, heart, brain and breast. Each practical EIT reconstruction algorithm should be efficient enough in terms of convergence rate, and accuracy. The main objective of this study is to investigate the feasibility of precise empirical conductivity imaging using a sinc-convolution algorithm in D-bar framework. At the first step, synthetic and experimental data were used to compute an intermediate object named scattering transform. Next, this object was used in a two-dimensional integral equation which was precisely and rapidly solved via sinc-convolution algorithm to find the square root of the conductivity for each pixel of image. For the purpose of comparison, multigrid and NOSER algorithms were implemented under a similar setting. Quality of reconstructions of synthetic models was tested against GREIT approved quality measures. To validate the simulation results, reconstructions of a phantom chest and a human lung were used. Evaluation of synthetic reconstructions shows that the quality of sinc-convolution reconstructions is considerably better than that of each of its competitors in terms of amplitude response, position error, ringing, resolution and shape-deformation. In addition, the results confirm near-exponential and linear convergence rates for sinc-convolution and multigrid, respectively. Moreover, the least degree of relative errors and the most degree of truth were found in sinc-convolution reconstructions from experimental phantom data. Reconstructions of clinical lung data show that the related physiological effect is well recovered by sinc-convolution algorithm. Parametric evaluation demonstrates the efficiency of sinc-convolution to reconstruct accurate conductivity images from experimental data. Excellent results in phantom and clinical reconstructions using sinc-convolution support parametric assessment results

  9. Precise two-dimensional D-bar reconstructions of human chest and phantom tank via sinc-convolution algorithm

    PubMed Central

    2012-01-01

    Background Electrical Impedance Tomography (EIT) is used as a fast clinical imaging technique for monitoring the health of the human organs such as lungs, heart, brain and breast. Each practical EIT reconstruction algorithm should be efficient enough in terms of convergence rate, and accuracy. The main objective of this study is to investigate the feasibility of precise empirical conductivity imaging using a sinc-convolution algorithm in D-bar framework. Methods At the first step, synthetic and experimental data were used to compute an intermediate object named scattering transform. Next, this object was used in a two-dimensional integral equation which was precisely and rapidly solved via sinc-convolution algorithm to find the square root of the conductivity for each pixel of image. For the purpose of comparison, multigrid and NOSER algorithms were implemented under a similar setting. Quality of reconstructions of synthetic models was tested against GREIT approved quality measures. To validate the simulation results, reconstructions of a phantom chest and a human lung were used. Results Evaluation of synthetic reconstructions shows that the quality of sinc-convolution reconstructions is considerably better than that of each of its competitors in terms of amplitude response, position error, ringing, resolution and shape-deformation. In addition, the results confirm near-exponential and linear convergence rates for sinc-convolution and multigrid, respectively. Moreover, the least degree of relative errors and the most degree of truth were found in sinc-convolution reconstructions from experimental phantom data. Reconstructions of clinical lung data show that the related physiological effect is well recovered by sinc-convolution algorithm. Conclusions Parametric evaluation demonstrates the efficiency of sinc-convolution to reconstruct accurate conductivity images from experimental data. Excellent results in phantom and clinical reconstructions using sinc

  10. Utilization of MAX and FAX human phantoms for space radiation exposure calculations using HZETRN

    NASA Astrophysics Data System (ADS)

    Qualls, Garry; Slaba, Tony; Clowdsley, Martha; Blattnig, Steve; Walker, Steven; Simonsen, Lisa

    To estimate astronaut health risk due to space radiation, one must have the ability to calculate, for known radiation environments external to the body, particle spectra, LET spectra, dose, dose equivalent, or gray equivalent that are averaged over specific organs or tissue types. This may be accomplished using radiation transport software and computational human body tissue models. Historically, NASA scientists have used the HZETRN software to calculate radiation transport through both vehicle shielding materials and body tissue. The Computerized Anatomical Man (CAM) and the Computerized Anatomical Female (CAF) body models, combined with the CAMERA software, have been used for body tissue self-shielding calculations. The CAM and CAF, which were developed in 1973 and 1992, respectively, model the 50th percentile U.S. Air Force male and female and are constructed using individual quadric surfaces that combine to form thousands of solid regions that represent specific tissues and structures within the body. In order to transport an external radiation environment to a point within one of the body models using HZETRN, a directional distribution of the tissues surrounding that point is needed. The CAMERA software is used to "ray trace" the CAM and CAF models, providing the thickness of each tissue type traversed along each of a large number of rays originating at a dose point. More recently, R. Kramer of the Departmento de Energia Nuclear, Universidade Federal de Pernambuco in Brazil and his co-workers developed the Male Adult voXel (MAX) model and the Female Adult voXel (FAX). These voxel-based body models were developed using segmented Computed Tomography (CT) scans of adult cadavers, and the quantities and distributions of various body tissues have been adjusted to match those specified in the International Commission on Radiological Protection (ICRP) reference adult male and female. A new set of tools has been developed to facilitate space radiation exposure

  11. SU-E-I-81: Assessment of CT Radiation Dose and Image Quality for An Automated Tube Potential Selection Algorithm Using Adult Anthropomorphic and ACR Phantoms

    SciTech Connect

    Mahmood, U; Erdi, Y; Wang, W

    2014-06-01

    Purpose: To assess the impact of General Electrics (GE) automated tube potential algorithm, kV assist (kVa) on radiation dose and image quality, with an emphasis on optimizing protocols based on noise texture. Methods: Radiation dose was assessed by inserting optically stimulated luminescence dosimeters (OSLs) throughout the body of an adult anthropomorphic phantom (CIRS). The baseline protocol was: 120 kVp, Auto mA (180 to 380 mA), noise index (NI) = 14, adaptive iterative statistical reconstruction (ASiR) of 20%, 0.8s rotation time. Image quality was evaluated by calculating the contrast to noise ratio (CNR) and noise power spectrum (NPS) from the ACR CT accreditation phantom. CNRs were calculated according to the steps described in ACR CT phantom testing document. NPS was determined by taking the 3D FFT of the uniformity section of the ACR phantom. NPS and CNR were evaluated with and without kVa and for all available adaptive iterative statistical reconstruction (ASiR) settings, ranging from 0 to 100%. Each NPS was also evaluated for its peak frequency difference (PFD) with respect to the baseline protocol. Results: The CNR for the adult male was found to decrease from CNR = 0.912 ± 0.045 for the baseline protocol without kVa to a CNR = 0.756 ± 0.049 with kVa activated. When compared against the baseline protocol, the PFD at ASiR of 40% yielded a decrease in noise magnitude as realized by the increase in CNR = 0.903 ± 0.023. The difference in the central liver dose with and without kVa was found to be 0.07%. Conclusion: Dose reduction was insignificant in the adult phantom. As determined by NPS analysis, ASiR of 40% produced images with similar noise texture to the baseline protocol. However, the CNR at ASiR of 40% with kVa fails to meet the current ACR CNR passing requirement of 1.0.

  12. NASA astronaut dosimetry: Implementation of scalable human phantoms and benchmark comparisons of deterministic versus Monte Carlo radiation transport

    NASA Astrophysics Data System (ADS)

    Bahadori, Amir Alexander

    Astronauts are exposed to a unique radiation environment in space. United States terrestrial radiation worker limits, derived from guidelines produced by scientific panels, do not apply to astronauts. Limits for astronauts have changed throughout the Space Age, eventually reaching the current National Aeronautics and Space Administration limit of 3% risk of exposure induced death, with an administrative stipulation that the risk be assured to the upper 95% confidence limit. Much effort has been spent on reducing the uncertainty associated with evaluating astronaut risk for radiogenic cancer mortality, while tools that affect the accuracy of the calculations have largely remained unchanged. In the present study, the impacts of using more realistic computational phantoms with size variability to represent astronauts with simplified deterministic radiation transport were evaluated. Next, the impacts of microgravity-induced body changes on space radiation dosimetry using the same transport method were investigated. Finally, dosimetry and risk calculations resulting from Monte Carlo radiation transport were compared with results obtained using simplified deterministic radiation transport. The results of the present study indicated that the use of phantoms that more accurately represent human anatomy can substantially improve space radiation dose estimates, most notably for exposures from solar particle events under light shielding conditions. Microgravity-induced changes were less important, but results showed that flexible phantoms could assist in optimizing astronaut body position for reducing exposures during solar particle events. Finally, little overall differences in risk calculations using simplified deterministic radiation transport and 3D Monte Carlo radiation transport were found; however, for the galactic cosmic ray ion spectra, compensating errors were observed for the constituent ions, thus exhibiting the need to perform evaluations on a particle

  13. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

    NASA Astrophysics Data System (ADS)

    Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-08-01

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  14. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms.

    PubMed

    Cros, Maria; Joemai, Raoul M S; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-07-17

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  15. The influence of tube voltage and phantom size in computed tomography on the dose-response relationship of dicentrics in human blood samples

    NASA Astrophysics Data System (ADS)

    Jost, G.; Lengsfeld, P.; Voth, M.; Schmid, E.; Pietsch, H.

    2010-06-01

    The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose levels up to 0.1 Gy using a 64-slice CT scanner. It was found that both the tube voltage and the phantom size significantly influenced the CT scan-induced linear dose-response relationship of dicentrics in human lymphocytes. Using the same phantom (standard abdomen), 80 kV CT x-rays were biologically more effective than 140 kV CT x-rays. However, it could also be determined that the applied phantom size had much more influence on the biological effectiveness. Obviously, the increasing slopes of the CT scan-induced dose response relationships of dicentrics in human lymphocytes obtained in a pediatric, a standard and an adipose abdomen have been induced by scattering effects of photons, which strongly increase with increasing phantom size.

  16. Human adult deglutition during sleep.

    PubMed

    Sato, Kiminori; Nakashima, Tadashi

    2006-05-01

    Clearance of the pharynx by deglutition is important in protecting the airway. The pattern of deglutition during sleep was investigated. Deglutition during sleep was examined in 8 normal human adults via time-matched recordings of polysomnography and surface electromyography (EMG) of the thyrohyoid and suprahyoid muscles. During sleep, deglutition was episodic, and was absent for long periods. The mean number of swallows per hour (+/-SD) during the total sleep time was 2.9 +/- 1.3. The mean period of the longest absence of deglutition was 50.6 +/- 10.2 minutes. Most deglutition occurred in association with spontaneous electroencephalographic arousal in rapid eye movement (REM) sleep and non-REM sleep. Deglutition was related to sleep stage. The mean number of swallows per hour was 7.2 +/- 3.5 during stage 1 sleep and 2.0 +/- 0.7 during stage 2 sleep. There was little deglutition during stages 3 and 4. The deeper the sleep stage became, the lower the mean deglutition frequency became. The mean number of swallows per hour was 2.7 +/- 2.2 during REM sleep. The EMG amplitude dropped to the lowest level of recording and hypotonic EMG activity increased during REM sleep. Deglutition, a vital function, is infrequent during sleep.

  17. [Theoretical and Experimental Dosimetry in Evaluation of Biological Effects of Electromagnetic Field for Portable Radio Transmitters. Report 2. Homogeneous Human Head Phantom].

    PubMed

    Perov, S Yu; Bogacheva, E V

    2015-01-01

    Results of theoretical (numerical) and experimental electromagnetic field dosimetry for homogeneous human head phantoms are considered. The simulation and measurement results are shown. This paper presents the results of Specific Absorption Rate (SAR) evaluation in the "special anthropomorphic model" of human head, when a source of electromagnetic radio frequency field is placed in front of the face. The minimal difference is shown between measurements and simulation results in Head Simulating Liquid, which makes it possible to conduct further brain tissue simulations. The investigations show that the type of electromagnetic field source and phantom form play an important part for SAR distribution.

  18. Optical imaging of green fluorescent protein markers for tracking vascular gene expression: a feasibility study in human tissue-like phantoms

    NASA Astrophysics Data System (ADS)

    Kumar, Ananda; Chen, Hunter H.; Long, Erin; Wang, Danming; Yang, Xiaoming

    2002-06-01

    Vascular gene therapy is an exciting approach to the treatment of cardiovascular diseases. However, to date, there are no imaging modalities available for non-invasive detection of vascular gene expression. We have developed an optical imaging method to track vascular gene expression by detecting fluorescent signals emitted from arterial walls following gene transfer. To investigate the feasibility of this new technique, we performed experiments on a set of human tissue-like phantoms using a common biological marker in gene therapy, the green fluorescent protein (GFP). The phantoms were constructed to mimic the arterial geometry beneath a tissue layer. Human smooth muscle cells transfected with GFP were embedded in a capillary tube in the phantom. Monte Carlo modeling of the phantom experiment was performed to optimize the performance of the optical imaging system. We compared the fluence rates among three types of light beams, including ring beam, Gaussian beam, and flat beam. The results showed that our optical imaging system was able to detect fluorescent signals up to 5-mm depth in the phantom, and that flat beam geometry would produce the optimum fluorescence remittance. This study provides valuable insights for improvements to the optical imaging system and refinement of the new technique to non-invasively detect/track vascular gene expression.

  19. Dynamics of hippocampal neurogenesis in adult humans

    PubMed Central

    Alkass, Kanar; Bernard, Samuel; Salehpour, Mehran; Huttner, Hagen B.; Boström, Emil; Westerlund, Isabelle; Vial, Celine; Buchholz, Bruce A.; Possnert, Göran; Mash, Deborah C.; Druid, Henrik; Frisén, Jonas

    2015-01-01

    Adult-born hippocampal neurons are important for cognitive plasticity in rodents. There is evidence for hippocampal neurogenesis in adult humans, although whether its extent is sufficient to have functional significance has been questioned. We have assessed the generation of hippocampal cells in humans by measuring the concentration of nuclear bomb test-derived 14C in genomic DNA and we present an integrated model of the cell turnover dynamics. We found that a large subpopulation of hippocampal neurons, constituting one third of the neurons, is subject to exchange. In adult humans, 700 new neurons are added per day, corresponding to an annual turnover of 1.75% of the neurons within the renewing fraction, with a modest decline during aging. We conclude that neurons are generated throughout adulthood and that the rates are comparable in middle aged humans and mice, suggesting that adult hippocampal neurogenesis may contribute to human brain function. PMID:23746839

  20. Monte Carlo modelling of angular radiance in tissue phantoms and human prostate: PDT light dosimetry.

    PubMed

    Barajas, O; Ballangrud, A M; Miller, G G; Moore, R B; Tulip, J

    1997-09-01

    Photodynamic therapy (PDT) is a promising technique for destroying tumours. Photosensitizing drugs presently available are not sufficiently tumour specific; hence, light dosimetry is required in order to control light exposure and thereby restrict cell kill to the target tissue to avoid damage to healthy tissue. Current light dosimetry methods rely on tissue optical characterization by fluence measurements at several points. Fluence-based tissue characterization is impractical for tumours in organs such as prostate where access by optical probes is limited and the tumours are highly optically inhomogeneous. This paper explores the potential of radiance-based light dosimetry as an alternative. Correlation is found between Monte Carlo simulation of radiance in a tissue phantom and radiance measurements made using a new radiance probe. Radiance is sensitive to variations in the tissue optical parameters, absorption coefficient mu(a), scattering coefficient mu(s), and anisotropy factor g, and therefore is potentially useful for tissue characterization. Radiance measurements have several advantages over fluence measurements. Radiance measurements provide more information from a single location, better spatial resolution of the tissue optical parameters, and higher sensitivity in discriminating between different media. However, the Monte Carlo method is too slow to be of practical value for tissue characterization by correlation of measured and simulated radiance. An analytical solution to the transport equation for radiance would be desirable as this would facilitate and increase the speed of tissue characterization.

  1. Analysis of mobile phone design features affecting radiofrequency power absorbed in a human head phantom.

    PubMed

    Kuehn, Sven; Kelsh, Michael A; Kuster, Niels; Sheppard, Asher R; Shum, Mona

    2013-09-01

    The US FCC mandates the testing of all mobile phones to demonstrate compliance with the rule requiring that the peak spatial SAR does not exceed the limit of 1.6 W/kg averaged over any 1 g of tissue. These test data, measured in phantoms with mobile phones operating at maximum antenna input power, permitted us to evaluate the variation in SARs across mobile phone design factors such as shape and antenna design, communication technology, and test date (over a 7-year period). Descriptive statistical summaries calculated for 850 MHz and 1900 MHz phones and ANOVA were used to evaluate the influence of the foregoing factors on SARs. Service technology accounted for the greatest variability in compliance test SARs that ranged from AMPS (highest) to CDMA, iDEN, TDMA, and GSM (lowest). However, the dominant factor for SARs during use is the time-averaged antenna input power, which may be much less than the maximum power used in testing. This factor is largely defined by the communication system; e.g., the GSM phone average output can be higher than CDMA by a factor of 100. Phone shape, antenna type, and orientation of a phone were found to be significant but only on the order of up to a factor of 2 (3 dB). The SAR in the tilt position was significantly smaller than for touch. The side of the head did not affect SAR levels significantly. Among the remaining factors, external antennae produced greater SARs than internal ones, and brick and clamshell phones produced greater SARs than slide phones. Assuming phone design and usage patterns do not change significantly over time, we have developed a normalization procedure and formula that permits reliable prediction of the relative SAR between various communication systems. This approach can be applied to improve exposure assessment in epidemiological research.

  2. Phantom validation for ultrasound to statistical shape model registration of human pelvis

    NASA Astrophysics Data System (ADS)

    Ghanavati, Sahar; Mousavi, Parvin; Fichtinger, Gabor; Abolmaesumi, Purang

    2011-03-01

    Total Hip Replacement (THR) has become a common surgical procedure in recent years, as a result of increasing aging population with osteoarthritis of the hip joint. Localization of the pelvic anatomical coordinate system (PaCS) is a critical step in accurate placement of the femur prosthesis in the acetabulum in THR. Intra-operative ultrasound (US) imaging can provide a radiation-free navigation system for localization of the PaCS. However, US images are noisy and cannot provide any anatomical information beneath the bone surface due to the total reflection of US beam at the bone-soft tissue interface. A solution to this problem is to fuse intra-operative US with pre-operative imaging or a statistical shape model (SSM) of the pelvis. Here, we propose a multi-slice to volume intensity-based registration of the pelvic SSM to a sparse set of 2D US images in order to localize the PaCS in the US. In this registration technique, a set of 2D slices are extracted from a pelvic SSM using the approximate location and orientation of their corresponding 2D US images. During the registration, the comparison between the SSM slices and the US images is made using an ultrasound simulation technique and a correlation-based similarity metric. We demonstrate the feasibility of our proposed approach in localizing the PaCS on five patient-based phantoms. These results indicate the necessity of including pubic symphysis landmarks in the 2D US slices in order to have a precise estimation of the PaCS.

  3. Automated quantification of myocardial infarction from MR images by accounting for partial volume effects: animal, phantom, and human study.

    PubMed

    Heiberg, Einar; Ugander, Martin; Engblom, Henrik; Götberg, Matthias; Olivecrona, Göran K; Erlinge, David; Arheden, Håkan

    2008-02-01

    Ethics committees approved human and animal study components; informed written consent was provided (prospective human study [20 men; mean age, 62 years]) or waived (retrospective human study [16 men, four women; mean age, 59 years]). The purpose of this study was to prospectively evaluate a clinically applicable method, accounting for the partial volume effect, to automatically quantify myocardial infarction from delayed contrast material-enhanced magnetic resonance images. Pixels were weighted according to signal intensity to calculate infarct fraction for each pixel. Mean bias +/- variability (or standard deviation), expressed as percentage left ventricular myocardium (%LVM), were -0.3 +/- 1.3 (animals), -1.2 +/- 1.7 (phantoms), and 0.3 +/- 2.7 (patients), respectively. Algorithm had lower variability than dichotomous approach (2.7 vs 7.7 %LVM, P < .01) and did not differ from interobserver variability for bias (P = .31) or variability (P = .38). The weighted approach provides automatic quantification of myocardial infarction with higher accuracy and lower variability than a dichotomous algorithm. (c) RSNA, 2007.

  4. Radiation dose measurements and Monte Carlo calculations for neutron and photon reactions in a human head phantom for accelerator-based boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kim, Don-Soo

    Dose measurements and radiation transport calculations were investigated for the interactions within the human brain of fast neutrons, slow neutrons, thermal neutrons, and photons associated with accelerator-based boron neutron capture therapy (ABNCT). To estimate the overall dose to the human brain, it is necessary to distinguish the doses from the different radiation sources. Using organic scintillators, human head phantom and detector assemblies were designed, constructed, and tested to determine the most appropriate dose estimation system to discriminate dose due to the different radiation sources that will ultimately be incorporated into a human head phantom to be used for dose measurements in ABNCT. Monoenergetic and continuous energy neutrons were generated via the 7Li(p,n)7Be reaction in a metallic lithium target near the reaction threshold using the 5.5 MV Van de Graaff accelerator at the University of Massachusetts Lowell. A human head phantom was built to measure and to distinguish the doses which result from proton recoils induced by fast neutrons, alpha particles and recoil lithium nuclei from the 10B(n,alpha)7Li reaction, and photons generated in the 7Li accelerator target as well as those generated inside the head phantom through various nuclear reactions at the same time during neutron irradiation procedures. The phantom consists of two main parts to estimate dose to tumor and dose to healthy tissue as well: a 3.22 cm3 boron loaded plastic scintillator which simulates a boron containing tumor inside the brain and a 2664 cm3 cylindrical liquid scintillator which represents the surrounding healthy tissue in the head. The Monte Carlo code MCNPX(TM) was used for the simulation of radiation transport due to neutrons and photons and extended to investigate the effects of neutrons and other radiation on the brain at various depths.

  5. Effectiveness of a New Lead-Shielding Device and Additional Filter for Reducing Staff and Patient Radiation Exposure During Videofluoroscopic Swallowing Study Using a Human Phantom.

    PubMed

    Morishima, Yoshiaki; Chida, Koichi; Muroya, Yoshikazu; Utsumi, Yoshiya

    2017-09-18

    Interventional radiology procedures often involve lengthy exposure to fluoroscopy-derived radiation. We therefore devised a videofluoroscopic swallowing study (VFSS) procedure using a human phantom that proved to protect the patient and physician by reducing the radiation dose. We evaluated a new lead-shielding device and separately attached additional filters (1.0-, 2.0-, and 3.0-mm Al filters and a 0.5-mm Cu filter) during VFSS to reduce the patient's entrance skin dose (ESD). A monitor attached to the human phantom's neck measured the ESD. We also developed another lead shield (VFSS Shielding Box, 1.0-mm Pb equivalent) and tested its efficacy using the human phantom and an ionization chamber radiation survey meter with and without protection from scattered radiation at the physician's position on the phantom. We then measured the scattered radiation (at 90 and 150 cm above the floor) after combining the filters with the VFSS Shielding Box. With the additional filters, the ESD was reduced by 15.4-55.1%. With the VFSS Shielding Box alone, the scattered radiation was reduced by about 10% compared with the dose without additional shielding. With the VFSS Shielding Box and filters combined, the scattered radiation dose was reduced by a maximum of about 44% at the physician's position. Thus, the additional lead-shielding device effectively provided protection from scattered radiation during fluoroscopy. These results indicate that the combined VFSS Shielding Box and filters can effectively reduce the physician's and patient's radiation doses.

  6. Dosimetry of a cone beam CT device for oral and maxillofacial radiology using Monte Carlo techniques and ICRP adult reference computational phantoms

    PubMed Central

    Morant, JJ; Salvadó, M; Hernández-Girón, I; Casanovas, R; Ortega, R; Calzado, A

    2013-01-01

    Objectives: The aim of this study was to calculate organ and effective doses for a range of available protocols in a particular cone beam CT (CBCT) scanner dedicated to dentistry and to derive effective dose conversion factors. Methods: Monte Carlo simulations were used to calculate organ and effective doses using the International Commission on Radiological Protection voxel adult male and female reference phantoms (AM and AF) in an i-CAT CBCT. Nine different fields of view (FOVs) were simulated considering full- and half-rotation modes, and also a high-resolution acquisition for a particular protocol. Dose–area product (DAP) was measured. Results: Dose to organs varied for the different FOVs, usually being higher in the AF phantom. For 360°, effective doses were in the range of 25–66 μSv, and 46 μSv for full head. Higher contributions to the effective dose corresponded to the remainder (31%; 27–36 range), salivary glands (23%; 20–29%), thyroid (13%; 8–17%), red bone marrow (10%; 9–11%) and oesophagus (7%; 4–10%). The high-resolution protocol doubled the standard resolution doses. DAP values were between 181 mGy cm2 and 556 mGy cm2 for 360°. For 180° protocols, dose to organs, effective dose and DAP were approximately 40% lower. A conversion factor (DAP to effective dose) of 0.130 ± 0.006 μSv mGy−1 cm−2 was derived for all the protocols, excluding full head. A wide variation in dose to eye lens and thyroid was found when shifting the FOV in the AF phantom. Conclusions: Organ and effective doses varied according to field size, acquisition angle and positioning of the beam relative to radiosensitive organs. Good positive correlation between calculated effective dose and measured DAP was found. PMID:22933532

  7. Dosimetry of a cone beam CT device for oral and maxillofacial radiology using Monte Carlo techniques and ICRP adult reference computational phantoms.

    PubMed

    Morant, J J; Salvadó, M; Hernández-Girón, I; Casanovas, R; Ortega, R; Calzado, A

    2013-01-01

    The aim of this study was to calculate organ and effective doses for a range of available protocols in a particular cone beam CT (CBCT) scanner dedicated to dentistry and to derive effective dose conversion factors. Monte Carlo simulations were used to calculate organ and effective doses using the International Commission on Radiological Protection voxel adult male and female reference phantoms (AM and AF) in an i-CAT CBCT. Nine different fields of view (FOVs) were simulated considering full- and half-rotation modes, and also a high-resolution acquisition for a particular protocol. Dose-area product (DAP) was measured. Dose to organs varied for the different FOVs, usually being higher in the AF phantom. For 360°, effective doses were in the range of 25-66 μSv, and 46 μSv for full head. Higher contributions to the effective dose corresponded to the remainder (31%; 27-36 range), salivary glands (23%; 20-29%), thyroid (13%; 8-17%), red bone marrow (10%; 9-11%) and oesophagus (7%; 4-10%). The high-resolution protocol doubled the standard resolution doses. DAP values were between 181 mGy cm(2) and 556 mGy cm(2) for 360°. For 180° protocols, dose to organs, effective dose and DAP were approximately 40% lower. A conversion factor (DAP to effective dose) of 0.130 ± 0.006 μSv mGy(-1) cm(-2) was derived for all the protocols, excluding full head. A wide variation in dose to eye lens and thyroid was found when shifting the FOV in the AF phantom. Organ and effective doses varied according to field size, acquisition angle and positioning of the beam relative to radiosensitive organs. Good positive correlation between calculated effective dose and measured DAP was found.

  8. Evaluation of organ doses and specific k effective dose of 64-slice CT thorax examination using an adult anthropomorphic phantom

    NASA Astrophysics Data System (ADS)

    Hashim, S.; Karim, M. K. A.; Bakar, K. A.; Sabarudin, A.; Chin, A. W.; Saripan, M. I.; Bradley, D. A.

    2016-09-01

    The magnitude of radiation dose in computed tomography (CT) depends on the scan acquisition parameters, investigated herein using an anthropomorphic phantom (RANDO®) and thermoluminescence dosimeters (TLD). Specific interest was in the organ doses resulting from CT thorax examination, the specific k coefficient for effective dose estimation for particular protocols also being determined. For measurement of doses representing five main organs (thyroid, lung, liver, esophagus and skin), TLD-100 (LiF:Mg, Ti) were inserted into selected holes in a phantom slab. Five CT thorax protocols were investigated, one routine (R1) and four that were modified protocols (R2 to R5). Organ doses were ranked from greatest to least, found to lie in the order: thyroid>skin>lung>liver>breast. The greatest dose, for thyroid at 25 mGy, was that in use of R1 while the lowest, at 8.8 mGy, was in breast tissue using R3. Effective dose (E) was estimated using three standard methods: the International Commission on Radiological Protection (ICRP)-103 recommendation (E103), the computational phantom CT-EXPO (E(CTEXPO)) method, and the dose-length product (DLP) based approach. E103 k factors were constant for all protocols, ~8% less than that of the universal k factor. Due to inconsistency in tube potential and pitch factor the k factors from CTEXPO were found to vary between 0.015 and 0.010 for protocols R3 and R5. With considerable variation between scan acquisition parameters and organ doses, optimization of practice is necessary in order to reduce patient organ dose.

  9. Sampling rate dependence of correlation at long time lags in BOLD fMRI measurements on humans and gel phantoms.

    PubMed

    Mikkelsen, Kaare B; Lund, Torben E

    2013-01-01

    The aim of this study is to investigate the effects of sampling rate on Hurst exponents derived from Blood Oxygenation Level Dependent functional Magnetic Resonance Imaging (BOLD fMRI) resting state time series. fMRI measurements were performed on 2 human subjects and a selection of gel phantoms. From these, Hurst exponents were calculated. It was found that low sampling rates induced non-trivial exponents at sharp material transitions, and that Hurst exponents of human measurements had a strong TR-dependence. The findings are compared to theoretical considerations regarding the fractional Gaussian noise model and resampling, and it is found that the implications are problematic. This result should have a direct influence on the way future studies of low-frequency variation in BOLD fMRI data are conducted, especially if the fractional Gaussian noise model is considered. We recommend either using a different model (examples of such are referenced in the conclusion), or standardizing experimental procedures along an optimal sampling rate.

  10. Secondary absorbed doses from light ion irradiation in anthropomorphic phantoms representing an adult male and a 10 year old child

    NASA Astrophysics Data System (ADS)

    Hultqvist, Martha; Gudowska, Irena

    2010-11-01

    Secondary organ absorbed doses were calculated by Monte Carlo simulations with the SHIELD-HIT07 code coupled with the mathematical anthropomorphic phantoms CHILD-HIT and ADAM-HIT. The simulated irradiations were performed with primary 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 100-400 MeV/u which were directly impinging on the phantoms, i.e. approximating scanned beams, and with a simplified beamline for 12C irradiation. The evaluated absorbed doses to the out-of-field organs were in the range 10-6 to 10-1 mGy per target Gy and with standard deviations 0.5-20%. While the contribution to the organ absorbed doses from secondary neutrons dominated in the ion beams of low atomic number Z, the produced charged fragments and their subsequent charged secondaries of higher generations became increasingly important for the secondary dose delivery as Z of the primary ions increased. As compared to the simulated scanned 12C ion beam, the implementation of a simplified beamline for prostate irradiation with 12C ions resulted in an increase of 2-50 times in the organ absorbed doses depending on the distance from the target volume. Comparison of secondary organ absorbed doses delivered by 1H and 12C beams showed smaller differences when the RBE for local tumor control of the ions was considered and normalization to the RBE-weighted dose to the target was performed.

  11. The UF series of tomographic computational phantoms of pediatric patients

    SciTech Connect

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

    2005-12-15

    Two classes of anthropomorphic computational phantoms exist for use in Monte Carlo radiation transport simulations: tomographic voxel phantoms based upon three-dimensional (3D) medical images, and stylized mathematical phantoms based upon 3D surface equations for internal organ definition. Tomographic phantoms have shown distinct advantages over the stylized phantoms regarding their similarity to real human anatomy. However, while a number of adult tomographic phantoms have been developed since the early 1990s, very few pediatric tomographic phantoms are presently available to support dosimetry in pediatric diagnostic and therapy examinations. As part of a larger effort to construct a series of tomographic phantoms of pediatric patients, five phantoms of different ages (9-month male, 4-year female, 8-year female, 11-year male, and 14-year male) have been constructed from computed tomography (CT) image data of live patients using an IDL-based image segmentation tool. Lungs, bones, and adipose tissue were automatically segmented through use of window leveling of the original CT numbers. Additional organs were segmented either semiautomatically or manually with the aid of both anatomical knowledge and available image-processing techniques. Layers of skin were created by adding voxels along the exterior contour of the bodies. The phantoms were created from fused images taken from head and chest-abdomen-pelvis CT exams of the same individuals (9-month and 4-year phantoms) or of two different individuals of the same sex and similar age (8-year, 11-year, and 14-year phantoms). For each model, the resolution and slice positions of the image sets were adjusted based upon their anatomical coverage and then fused to a single head-torso image set. The resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year, and 14-year are 0.43x0.43x3.0 mm, 0.45x0.45x5.0 mm, 0.58x0.58x6.0 mm, 0.47x0.47x6.00 mm, and 0.625x0.625x6.0 mm, respectively. While organ masses can be

  12. The UF series of tomographic computational phantoms of pediatric patients.

    PubMed

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

    2005-12-01

    Two classes of anthropomorphic computational phantoms exist for use in Monte Carlo radiation transport simulations: tomographic voxel phantoms based upon three-dimensional (3D) medical images, and stylized mathematical phantoms based upon 3D surface equations for internal organ definition. Tomographic phantoms have shown distinct advantages over the stylized phantoms regarding their similarity to real human anatomy. However, while a number of adult tomographic phantoms have been developed since the early 1990s, very few pediatric tomographic phantoms are presently available to support dosimetry in pediatric diagnostic and therapy examinations. As part of a larger effort to construct a series of tomographic phantoms of pediatric patients, five phantoms of different ages (9-month male, 4-year female, 8-year female, 11-year male, and 14-year male) have been constructed from computed tomography (CT) image data of live patients using an IDL-based image segmentation tool. Lungs, bones, and adipose tissue were automatically segmented through use of window leveling of the original CT numbers. Additional organs were segmented either semiautomatically or manually with the aid of both anatomical knowledge and available image-processing techniques. Layers of skin were created by adding voxels along the exterior contour of the bodies. The phantoms were created from fused images taken from head and chest-abdomen-pelvis CT exams of the same individuals (9-month and 4-year phantoms) or of two different individuals of the same sex and similar age (8-year, 11-year, and 14-year phantoms). For each model, the resolution and slice positions of the image sets were adjusted based upon their anatomical coverage and then fused to a single head-torso image set. The resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year, and 14-year are 0.43 x 0.43 x 3.0 mm, 0.45 x 0.45 x 5.0 mm, 0.58 x 0.58 x 6.0 mm, 0.47 X 0.47 x 6.00 mm, and 0.625 x 0.625 x 6.0 mm, respectively. While organ

  13. Mechanical characterization of human brain tumors from patients and comparison to potential surgical phantoms.

    PubMed

    Stewart, Daniel C; Rubiano, Andrés; Dyson, Kyle; Simmons, Chelsey S

    2017-01-01

    While mechanical properties of the brain have been investigated thoroughly, the mechanical properties of human brain tumors rarely have been directly quantified due to the complexities of acquiring human tissue. Quantifying the mechanical properties of brain tumors is a necessary prerequisite, though, to identify appropriate materials for surgical tool testing and to define target parameters for cell biology and tissue engineering applications. Since characterization methods vary widely for soft biological and synthetic materials, here, we have developed a characterization method compatible with abnormally shaped human brain tumors, mouse tumors, animal tissue and common hydrogels, which enables direct comparison among samples. Samples were tested using a custom-built millimeter-scale indenter, and resulting force-displacement data is analyzed to quantify the steady-state modulus of each sample. We have directly quantified the quasi-static mechanical properties of human brain tumors with effective moduli ranging from 0.17-16.06 kPa for various pathologies. Of the readily available and inexpensive animal tissues tested, chicken liver (steady-state modulus 0.44 ± 0.13 kPa) has similar mechanical properties to normal human brain tissue while chicken crassus gizzard muscle (steady-state modulus 3.00 ± 0.65 kPa) has similar mechanical properties to human brain tumors. Other materials frequently used to mimic brain tissue in mechanical tests, like ballistic gel and chicken breast, were found to be significantly stiffer than both normal and diseased brain tissue. We have directly compared quasi-static properties of brain tissue, brain tumors, and common mechanical surrogates, though additional tests would be required to determine more complex constitutive models.

  14. Mechanical characterization of human brain tumors from patients and comparison to potential surgical phantoms

    PubMed Central

    Rubiano, Andrés; Dyson, Kyle; Simmons, Chelsey S.

    2017-01-01

    While mechanical properties of the brain have been investigated thoroughly, the mechanical properties of human brain tumors rarely have been directly quantified due to the complexities of acquiring human tissue. Quantifying the mechanical properties of brain tumors is a necessary prerequisite, though, to identify appropriate materials for surgical tool testing and to define target parameters for cell biology and tissue engineering applications. Since characterization methods vary widely for soft biological and synthetic materials, here, we have developed a characterization method compatible with abnormally shaped human brain tumors, mouse tumors, animal tissue and common hydrogels, which enables direct comparison among samples. Samples were tested using a custom-built millimeter-scale indenter, and resulting force-displacement data is analyzed to quantify the steady-state modulus of each sample. We have directly quantified the quasi-static mechanical properties of human brain tumors with effective moduli ranging from 0.17–16.06 kPa for various pathologies. Of the readily available and inexpensive animal tissues tested, chicken liver (steady-state modulus 0.44 ± 0.13 kPa) has similar mechanical properties to normal human brain tissue while chicken crassus gizzard muscle (steady-state modulus 3.00 ± 0.65 kPa) has similar mechanical properties to human brain tumors. Other materials frequently used to mimic brain tissue in mechanical tests, like ballistic gel and chicken breast, were found to be significantly stiffer than both normal and diseased brain tissue. We have directly compared quasi-static properties of brain tissue, brain tumors, and common mechanical surrogates, though additional tests would be required to determine more complex constitutive models. PMID:28582392

  15. Microwave stethoscope: development and benchmarking of a vital signs sensor using computer-controlled phantoms and human studies.

    PubMed

    Celik, Nuri; Gagarin, Ruthsenne; Huang, Gui Chao; Iskander, Magdy F; Berg, Benjamin W

    2014-08-01

    This paper describes a new microwave-based method and associated measurement system for monitoring multiple vital signs (VS) as well as the changes in lung water content. The measurement procedure utilizes a single microwave sensor for reflection coefficient measurements, hence the name "microwave stethoscope (MiSt)," as opposed to the two-sensor transmission method previously proposed by the authors. To compensate for the reduced sensitivity due to reflection coefficient measurements, an improved microwave sensor design with enhanced matching to the skin and broadband operation, as well as an advanced digital signal processing algorithm are used in developing the MiSt. Results from phantom experiments and human clinical trials are described. The results clearly demonstrate that MiSt provides reliable monitoring of multiple VS such as the respiration rate, heart rate, and the changes in lung water content through a single microwave measurement. In addition, information such as heart waveforms that correlates well with electrocardiogram is observed from these microwave measurements. Details of the broadband sensor design, experimental procedure, DSP algorithms used for VS extraction, and obtained results are presented and discussed.

  16. Infant phantom head circuit board for EEG head phantom and pediatric brain simulation

    NASA Astrophysics Data System (ADS)

    Almohsen, Safa

    The infant's skull differs from an adult skull because of the characteristic features of the human skull during early development. The fontanels and the conductivity of the infant skull influence surface currents, generated by neurons, which underlie electroencephalography (EEG) signals. An electric circuit was built to power a set of simulated neural sources for an infant brain activity simulator. Also, in the simulator, three phantom tissues were created using saline solution plus Agarose gel to mimic the conductivity of each layer in the head [scalp, skull brain]. The conductivity measurement was accomplished by two different techniques: using the four points' measurement technique, and a conductivity meter. Test results showed that the optimized phantom tissues had appropriate conductivities to simulate each tissue layer to fabricate a physical head phantom. In this case, the best results should be achieved by testing the electrical neural circuit with the sample physical model to generate simulated EEG data and use that to solve both the forward and the inverse problems for the purpose of localizing the neural sources in the head phantom.

  17. RPI-AM and RPI-AF, a pair of mesh-based, size-adjustable adult male and female computational phantoms using ICRP-89 parameters and their calculations for organ doses from monoenergetic photon beams

    PubMed Central

    Zhang, Juying; Na, Yong Hum; Caracappa, Peter F; Xu, X George

    2010-01-01

    This paper describes the development of a pair of adult male and adult female computational phantoms that are compatible with anatomical parameters for the 50th percentile population as specified by the International Commission on Radiological Protection (ICRP). The phantoms were designed entirely using polygonal mesh surfaces—a Boundary REPresentation (BREP) geometry that affords the ability to efficiently deform the shape and size of individual organs, as well as the body posture. A set of surface mesh models, from Anatomium™ 3D P1 V2.0, including 140 organs (out of 500 available) was adopted to supply the basic anatomical representation at the organ level. The organ masses were carefully adjusted to agree within 0.5% relative error with the reference values provided in the ICRP Publication 89. The finalized phantoms have been designated the RPI adult male (RPI-AM) and adult female (RPI-AF) phantoms. For the purposes of organ dose calculations using the MCNPX Monte Carlo code, these phantoms were subsequently converted to voxel formats. Monoenergetic photons between 10 keV and 10 MeV in six standard external photon source geometries were considered in this study: four parallel beams (anterior–posterior, posterior–anterior, left lateral and right lateral), one rotational and one isotropic. The results are tabulated as fluence-to-organ-absorbed-dose conversion coefficients and fluence-to-effective-dose conversion coefficients and compared against those derived from the ICRP computational phantoms, REX and REGINA. A general agreement was found for the effective dose from these two sets of phantoms for photon energies greater than about 300 keV. However, for low-energy photons and certain individual organs, the absorbed doses exhibit profound differences due to specific anatomical features. For example, the position of the arms affects the dose to the lung by more than 20% below 300 keV in the lateral source directions, and the vertical position of the testes

  18. Development of 5- and 10-year-old pediatric phantoms based on polygon mesh surfaces

    SciTech Connect

    Melo Lima, V. J. de; Cassola, V. F.; Kramer, R.; Oliveira Lira, C. A. B. de; Khoury, H. J.; Vieira, J. W.

    2011-08-15

    Purpose: The purpose of this study is the development of reference pediatric phantoms for 5- and 10-year-old children to be used for the calculation of organ and tissue equivalent doses in radiation protection. Methods: The study proposes a method for developing anatomically highly sophisticated pediatric phantoms without using medical images. The 5- and 10-year-old male and female phantoms presented here were developed using 3D modeling software applied to anatomical information taken from atlases and textbooks. The method uses polygon mesh surfaces to model body contours, the shape of organs as well as their positions, and orientations in the human body. Organ and tissue masses comply with the corresponding data given by the International Commission on Radiological Protection (ICRP) for the 5- and 10-year-old reference children. Bones were segmented into cortical bone, spongiosa, medullary marrow, and cartilage to allow for the use of micro computer tomographic ({mu}CT) images of trabecular bone for skeletal dosimetry. Results: The four phantoms, a male and a female for each age, and their organs are presented in 3D images and their organ and tissue masses in tables which show the compliance of the ICRP reference values. Dosimetric data, calculated for the reference pediatric phantoms by Monte Carlo methods were compared with corresponding data from adult mesh phantoms and pediatric stylized phantoms. The comparisons show reasonable agreement if the anatomical differences between the phantoms are properly taken into account. Conclusions: Pediatric phantoms were developed without using medical images of patients or volunteers for the first time. The models are reference phantoms, suitable for regulatory dosimetry, however, the 3D modeling method can also be applied to medical images to develop patient-specific phantoms.

  19. Proposal for study on IR light and glucose phantom interaction for human glucose quantification applications

    NASA Astrophysics Data System (ADS)

    Romo-Cárdenas, Gerardo S.; Sanchez-Lopez, Juan D.; Nieto-Hipolito, Juan I.; Cosio-León, María.; Luque-Morales, Priscy; Vazquez-Briseno, Mabel

    2016-09-01

    It has been established the importance of a constant glucose monitoring in order to keep a regular control for diabetes patients. Several medical studies accept the necessity of exploring alternatives for the traditional digital glucometer, given the pain and discomfort related to this technique, which can lead to a compromised control of the disease. Several efforts based on the application of IR spectroscopy had been done with favorable, yet not conclusive results. Therefore it's necessary to apply a comprehensive and interdisciplinary study based on the biochemical and optical properties of the glucose in the human body, in order to understand the interaction between this substance, its surroundings and IR light. These study propose a comprehensive approach of the glucose and IR light interaction, considering and combining important biochemical, physiological and optical properties, as well as some machine learning techniques for the data analysis. The results of this work would help to define the right parameters aiming to obtain an optical glucose quantification system and protocol.

  20. The neutron dose conversion coefficients calculation in human tooth enamel in an anthropomorphic phantom.

    PubMed

    Khailov, A M; Ivannikov, A I; Skvortsov, V G; Stepanenko, V F; Tsyb, A F; Trompier, F; Hoshi, M

    2010-02-01

    In the present study, MCNP4B simulation code is used to simulate neutron and photon transport. It gives the conversion coefficients that relate neutron fluence to the dose in tooth enamel (molars and pre-molars only) for 20 energy groups of monoenergetic neutrons with energies from 10-9 to 20 MeV for five different irradiation geometries. The data presented are intended to provide the basis for connection between EPR dose values and standard protection quantities defined in ICRP Publication 74. The results of the calculations for critical organs were found to be consistent with ICRP data, with discrepancies generally less than 10% for the fast neutrons. The absorbed dose in enamel was found to depend strongly on the incident neutron energy for neutrons over 10 keV. The dependence of the data on the irradiation geometry is also shown. Lower bound estimates of enamel radiation sensitivity to neutrons were made using obtained coefficients for the secondary photons. Depending on neutron energy, tooth enamel was shown to register 10-120% of the total neutron dose in the human body in the case of pure neutron exposure and AP irradiation geometry.

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

    PubMed

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

    2003-01-21

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

  2. An effective dose assessment technique with NORM added consumer products using skin-point source on computational human phantom.

    PubMed

    Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Hyun Cheol; Choi, Hyun Joon; Testa, Mauro; Lee, Jae Kook; Yeom, Yeon Soo; Kim, Chan Hyeong; Min, Chul Hee

    2016-12-01

    The aim of this study is to develop the assessment technique of the effective dose by calculating the organ equivalent dose with a Monte Carlo (MC) simulation and a computational human phantom for the naturally occurring radioactive material (NORM) added consumer products. In this study, we suggests the method determining the MC source term based on the skin-point source enabling the convenient and conservative modeling of the various type of the products. To validate the skin-point source method, the organ equivalent doses were compared with that by the product modeling source of the realistic shape for the pillow, waist supporter, sleeping mattress etc. Our results show that according to the source location, the organ equivalent doses were observed as the similar tendency for both source determining methods, however, it was observed that the annual effective dose with the skin-point source was conservative than that with the modeling source with the maximum 3.3 times higher dose. With the assumption of the gamma energy of 1MeV and product activity of 1Bqg(-1), the annual effective doses of the pillow, waist supporter and sleeping mattress with skin-point source was 3.09E-16SvBq(-1)year(-1), 1.45E-15SvBq(-1)year(-1), and 2,82E-16SvBq(-1)year(-1), respectively, while the product modeling source showed 9.22E-17SvBq(-1)year(-1), 9.29E-16SvBq(-1)year(-1), and 8.83E-17SvBq(-1)year(-1), respectively. In conclusion, it was demonstrated in this study that the skin-point source method could be employed to efficiently evaluate the annual effective dose due to the usage of the NORM added consumer products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Development of a multi-wavelength diffuse optical tomography system for early diagnosis of rheumatoid arthritis: simulation, phantoms and healthy human studies

    PubMed Central

    Wu, Hao Yang; Filer, Andrew; Styles, Iain; Dehghani, Hamid

    2016-01-01

    A multi-wavelength diffuse optical tomography (DOT) system has been developed to directly extract physiological information, such as total haemoglobin concentration, from tissue in human hand joints. Novel methods for 3D surface imaging and spectrally constrained image reconstruction are introduced and their potential application to imaging of rheumatoid arthritis is discussed. Results are presented from simulation studies as well as experiments using phantoms and data from imaging of three healthy volunteers. The image features are recovered partially for phantom data using transmission measurements only. Images that reveal joint regions and surrounding features within the hand are shown to co-register with co–acquired ultrasound images which are shown to be related to total haemoglobin concentration. PMID:27896015

  4. Is there reliable experimental evidence for different dicentric yields in human lymphocytes produced by mammography X-rays free-in-air and within a phantom?

    PubMed

    Büermann, L; Krumrey, M; Haney, M; Schmid, E

    2005-05-01

    We examined the production of dicentrics in human lymphocytes irradiated with 29 kV X-rays to a depth of 13.5 mm in a PMMA phantom. For these irradiation conditions, which are appropriate for the diagnostic application of mammography X-rays, a coefficient alpha of (5.88+/-0.66) x 10(-2) Gy(-1) of the linear quadratic dose-response relationship was determined. This value does not differ significantly from the coefficient alpha of (6.55+/-0.97) x 10(-2) Gy(-1) obtained earlier for a free-in-air set-up using blood of the same donor. The results are interpreted in terms of both the energy distributions of the photon fluence of mammography X-rays free-in-air and those in the PMMA phantom. Based on earlier results of experiments with monochromatic X-rays in the energy range 1.83-40 keV (completed here by an additional measurement at 25 keV), a fit function alpha(E) to the measured alpha coefficients as a function of the energy E of monochromatic X-rays was used to calculate weighted mean values alpha for both the mammography X-ray spectra free-in-air and in the phantom. As a result, weighted mean values of (4.9+/-1.0) x 10(-2) Gy(-1) and (4.5+/-1.0) x 10(-2) Gy(-1) were obtained, respectively. Although the measured alpha coefficients for mammography X-rays appear to be systematically higher than those calculated as weighted mean values alpha, it can be concluded that the modification of the mammography X-ray spectrum to a depth of 13.5 mm in a PMMA phantom compared with the free-in-air spectrum has no significant influence on the dicentric yields in human lymphocytes.

  5. Angiogenic properties of adult human thymus fat.

    PubMed

    Salas, Julián; Montiel, Mercedes; Jiménez, Eugenio; Valenzuela, Miguel; Valderrama, José Francisco; Castillo, Rafael; González, Sergio; El Bekay, Rajaa

    2009-11-01

    The endogenous proangiogenic properties of adipose tissue are well recognized. Although the adult human thymus has long been known to degenerate into fat tissue, it has never been considered as a potential source of angiogenic factors. We have investigated the expression of diverse angiogenic factors, including vascular endothelial growth factor A and B, angiopoietin 1, and tyrosine-protein kinase receptor-2 (an angiopoietin receptor), and then analyzed their physiological role on endothelial cell migration and proliferation, two relevant events in angiogenesis. The detection of the gene and protein expression of the various proteins has been performed by immunohistochemistry, Western blotting, and quantitative real-time polymerase chain reaction. We show, for the first time, that adult thymus fat produces a variety of angiogenic factors and induces the proliferation and migration of human umbilical cord endothelial cells. Based on these findings, we suggest that this fat has a potential angiogenic function that might affect thymic function and ongoing adipogenesis within the thymus.

  6. Comparison of organ dose and dose equivalent using ray tracing of male and female Voxel phantoms to space flight phantom torso data

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Hee; Qualls, Garry; Slaba, Tony; Cucinotta, Francis A.

    Phantom torso experiments have been flown on the space shuttle and International Space Station (ISS) providing validation data for radiation transport models of organ dose and dose equivalents. We describe results for space radiation organ doses using a new human geometry model based on detailed Voxel phantoms models denoted for males and females as MAX (Male Adult voXel) and Fax (Female Adult voXel), respectively. These models represent the human body with much higher fidelity than the CAMERA model currently used at NASA. The MAX and FAX models were implemented for the evaluation of directional body shielding mass for over 1500 target points of major organs. Radiation exposure to solar particle events (SPE), trapped protons, and galactic cosmic rays (GCR) were assessed at each specific site in the human body by coupling space radiation transport models with the detailed body shielding mass of MAX/FAX phantom. The development of multiple-point body-shielding distributions at each organ site made it possible to estimate the mean and variance of space dose equivalents at the specific organ. For the estimate of doses to the blood forming organs (BFOs), active marrow distributions in adult were accounted at bone marrow sites over the human body. We compared the current model results to space shuttle and ISS phantom torso experiments and to calculations using the CAMERA model.

  7. Comparison of Organ Dose and Dose Equivalent Using Ray Tracing of Male and Female Voxel Phantoms to Space Flight Phantom Torso Data

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Qualls, Garry D.; Cucinotta, Francis A.

    2008-01-01

    Phantom torso experiments have been flown on the space shuttle and International Space Station (ISS) providing validation data for radiation transport models of organ dose and dose equivalents. We describe results for space radiation organ doses using a new human geometry model based on detailed Voxel phantoms models denoted for males and females as MAX (Male Adult voXel) and Fax (Female Adult voXel), respectively. These models represent the human body with much higher fidelity than the CAMERA model currently used at NASA. The MAX and FAX models were implemented for the evaluation of directional body shielding mass for over 1500 target points of major organs. Radiation exposure to solar particle events (SPE), trapped protons, and galactic cosmic rays (GCR) were assessed at each specific site in the human body by coupling space radiation transport models with the detailed body shielding mass of MAX/FAX phantom. The development of multiple-point body-shielding distributions at each organ site made it possible to estimate the mean and variance of space dose equivalents at the specific organ. For the estimate of doses to the blood forming organs (BFOs), active marrow distributions in adult were accounted at bone marrow sites over the human body. We compared the current model results to space shuttle and ISS phantom torso experiments and to calculations using the CAMERA model.

  8. Comparison of Organ Dose and Dose Equivalent Using Ray Tracing of Male and Female Voxel Phantoms to Space Flight Phantom Torso Data

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Qualls, Garry D.; Cucinotta, Francis A.

    2008-01-01

    Phantom torso experiments have been flown on the space shuttle and International Space Station (ISS) providing validation data for radiation transport models of organ dose and dose equivalents. We describe results for space radiation organ doses using a new human geometry model based on detailed Voxel phantoms models denoted for males and females as MAX (Male Adult voXel) and Fax (Female Adult voXel), respectively. These models represent the human body with much higher fidelity than the CAMERA model currently used at NASA. The MAX and FAX models were implemented for the evaluation of directional body shielding mass for over 1500 target points of major organs. Radiation exposure to solar particle events (SPE), trapped protons, and galactic cosmic rays (GCR) were assessed at each specific site in the human body by coupling space radiation transport models with the detailed body shielding mass of MAX/FAX phantom. The development of multiple-point body-shielding distributions at each organ site made it possible to estimate the mean and variance of space dose equivalents at the specific organ. For the estimate of doses to the blood forming organs (BFOs), active marrow distributions in adult were accounted at bone marrow sites over the human body. We compared the current model results to space shuttle and ISS phantom torso experiments and to calculations using the CAMERA model.

  9. MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research

    PubMed Central

    Paul Segars, W.; Tsui, Benjamin M. W.

    2012-01-01

    Recent work in the development of computerized phantoms has focused on the creation of ideal “hybrid” models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be

  10. In vivo noninvasive 4D pressure difference mapping in the human aorta: phantom comparison and application in healthy volunteers and patients.

    PubMed

    Bock, Jelena; Frydrychowicz, Alex; Lorenz, Ramona; Hirtler, Daniel; Barker, Alex J; Johnson, Kevin M; Arnold, Raoul; Burkhardt, Hans; Hennig, Juergen; Markl, Michael

    2011-10-01

    In this work, we present a systematic phantom comparison and clinical application of noninvasive pressure difference mapping in the human aorta based on time-resolved 3D phase contrast data. Relative pressure differences were calculated based on integration and iterative refinement of pressure gradients derived from MR-based three-directional velocity vector fields (flow-sensitive 4D MRI with spatial/temporal resolution ∼ 2.1 mm(3)/40 ms) using the Navier-Stokes equation. After in vitro study using a stenosis phantom, time-resolved 3D pressure gradients were systematically evaluated in the thoracic aorta in a group of 12 healthy subjects and 6 patients after repair for aortic coarctation. Results from the phantom study showed good agreement with expected values and standard methods (Bernoulli). Data of healthy subjects showed good intersubject consistency and good agreement with the literature. In patients, pressure waveforms showed elevated peak values. Pressure gradients across the stenosis were compared with reference measurements from Doppler ultrasound. The MRI findings demonstrated a significant correlation (r = 0.96, P < 0.05) but moderate underestimation (14.7% ± 15.5%) compared with ultrasound when the maximum pressure difference for all possible paths connecting proximal and distal locations of the stenosis were used. This study demonstrates the potential of the applied approach to derive additional quantitative information such as pressure gradients from time-resolved 3D phase contrast MRI. Copyright © 2011 Wiley-Liss, Inc.

  11. Motion compensation for brain PET imaging using wireless MR active markers in simultaneous PET-MR: phantom and non-human primate studies.

    PubMed

    Huang, Chuan; Ackerman, Jerome L; Petibon, Yoann; Normandin, Marc D; Brady, Thomas J; El Fakhri, Georges; Ouyang, Jinsong

    2014-05-01

    Brain PET scanning plays an important role in the diagnosis, prognostication and monitoring of many brain diseases. Motion artifacts from head motion are one of the major hurdles in brain PET. In this work, we propose to use wireless MR active markers to track head motion in real time during a simultaneous PET-MR brain scan and incorporate the motion measured by the markers in the listmode PET reconstruction. Several wireless MR active markers and a dedicated fast MR tracking pulse sequence module were built. Data were acquired on an ACR Flangeless PET phantom with multiple spheres and a non-human primate with and without motion. Motions of the phantom and monkey's head were measured with the wireless markers using a dedicated MR tracking sequence module. The motion PET data were reconstructed using list-mode reconstruction with and without motion correction. Static reference was used as gold standard for quantitative analysis. The motion artifacts, which were prominent on the images without motion correction, were eliminated by the wireless marker based motion correction in both the phantom and monkey experiments. Quantitative analysis was performed on the phantom motion data from 24 independent noise realizations. The reduction of bias of sphere-to-background PET contrast by active marker based motion correction ranges from 26% to 64% and 17% to 25% for hot (i.e., radioactive) and cold (i.e., non-radioactive) spheres, respectively. The motion correction improved the channelized Hotelling observer signal-to-noise ratio of the spheres by 1.2 to 6.9 depending on their locations and sizes. The proposed wireless MR active marker based motion correction technique removes the motion artifacts in the reconstructed PET images and yields accurate quantitative values. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Fluence-to-dose conversion coefficients for neutrons and protons calculated using the PHITS code and ICRP/ICRU adult reference computational phantoms.

    PubMed

    Sato, Tatsuhiko; Endo, Akira; Zankl, Maria; Petoussi-Henss, Nina; Niita, Koji

    2009-04-07

    The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation and tissue weighting factors, w(R) and w(T), respectively, as revised in ICRP Publication 103 were employed. The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of the absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. By comparing these data with the corresponding data for the effective dose, we found that the numerical compatibilities of the revised w(R) with the Q(L) and Q(y) relationships are fairly established. The calculated data of these dose conversion coefficients are indispensable for constructing the radiation protection systems based on the new recommendations given in ICRP103 for aircrews and astronauts, as well as for workers in accelerators and nuclear facilities.

  13. Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms.

    PubMed

    Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji

    2011-03-01

    Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry. © Springer-Verlag 2010

  14. Uniquely hominid features of adult human astrocytes.

    PubMed

    Oberheim, Nancy Ann; Takano, Takahiro; Han, Xiaoning; He, Wei; Lin, Jane H C; Wang, Fushun; Xu, Qiwu; Wyatt, Jeffrey D; Pilcher, Webster; Ojemann, Jeffrey G; Ransom, Bruce R; Goldman, Steven A; Nedergaard, Maiken

    2009-03-11

    Defining the microanatomic differences between the human brain and that of other mammals is key to understanding its unique computational power. Although much effort has been devoted to comparative studies of neurons, astrocytes have received far less attention. We report here that protoplasmic astrocytes in human neocortex are 2.6-fold larger in diameter and extend 10-fold more GFAP (glial fibrillary acidic protein)-positive primary processes than their rodent counterparts. In cortical slices prepared from acutely resected surgical tissue, protoplasmic astrocytes propagate Ca(2+) waves with a speed of 36 microm/s, approximately fourfold faster than rodent. Human astrocytes also transiently increase cystosolic Ca(2+) in response to glutamatergic and purinergic receptor agonists. The human neocortex also harbors several anatomically defined subclasses of astrocytes not represented in rodents. These include a population of astrocytes that reside in layers 5-6 and extend long fibers characterized by regularly spaced varicosities. Another specialized type of astrocyte, the interlaminar astrocyte, abundantly populates the superficial cortical layers and extends long processes without varicosities to cortical layers 3 and 4. Human fibrous astrocytes resemble their rodent counterpart but are larger in diameter. Thus, human cortical astrocytes are both larger, and structurally both more complex and more diverse, than those of rodents. On this basis, we posit that this astrocytic complexity has permitted the increased functional competence of the adult human brain.

  15. The perception of phantom limbs. The D. O. Hebb lecture.

    PubMed

    Ramachandran, V S; Hirstein, W

    1998-09-01

    Almost everyone who has a limb amputated will experience a phantom limb--the vivid impression that the limb is not only still present, but in some cases, painful. There is now a wealth of empirical evidence demonstrating changes in cortical topography in primates following deafferentation or amputation, and this review will attempt to relate these in a systematic way to the clinical phenomenology of phantom limbs. With the advent of non-invasive imaging techniques such as MEG (magnetoencephalogram) and functional MRI, topographical reorganization can also be demonstrated in humans, so that it is now possible to track perceptual changes and changes in cortical topography in individual patients. We suggest, therefore, that these patients provide a valuable opportunity not only for exploring neural plasticity in the adult human brain but also for understanding the relationship between the activity of sensory neurons and conscious experience. We conclude with a theory of phantom limbs, some striking demonstrations of phantoms induced in normal subjects, and some remarks about the relevance of these phenomena to the question of how the brain constructs a 'body image.'

  16. Ultrasound Phantoms to Protect Patients from Novices

    PubMed Central

    2016-01-01

    With the growing use of ultrasound for pain management, we are interested in how to teach and practice ultrasound-guided procedures. Ethically, we should not insert a needle in a patient until after much practice on a phantom. Several types of phantoms have been introduced for ultrasound training, including water, agar/gelatin, elastomeric rubber, and meat phantoms and cadavers. The ideal phantom is similar to human tissue, is readily available and inexpensive, can be used repeatedly, provides tactile feedback, will hold a needle in place, does not generate needle tracks, and is not a health hazard. Several studies have shown the effectiveness of phantoms for improving the proficiency of novices. We hope that the application of phantoms in education leads to improved proficiency and increased patient safety. PMID:27103961

  17. Computerized Virtual Reality Simulation in Preclinical Dentistry: Can a Computerized Simulator Replace the Conventional Phantom Heads and Human Instruction?

    PubMed

    Plessas, Anastasios

    2017-10-01

    In preclinical dental education, the acquisition of clinical, technical skills, and the transfer of these skills to the clinic are paramount. Phantom heads provide an efficient way to teach preclinical students dental procedures safely while increasing their dexterity skills considerably. Modern computerized phantom head training units incorporate features of virtual reality technology and the ability to offer concurrent augmented feedback. The aims of this review were to examine and evaluate the dental literature for evidence supporting their use and to discuss the role of augmented feedback versus the facilitator's instruction. Adjunctive training in these units seems to enhance student's learning and skill acquisition and reduce the required faculty supervision time. However, the virtual augmented feedback cannot be used as the sole method of feedback, and the facilitator's input is still critical. Well-powered longitudinal randomized trials exploring the impact of these units on student's clinical performance and issues of cost-effectiveness are warranted.

  18. Dose conversion coefficients for electron exposure of the human eye lens: calculations including a whole body phantom.

    PubMed

    Behrens, R

    2013-07-01

    In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0°, 15°, 30° and 45°, respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0°, 180° and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0° up to 180° in steps of 15° and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0° (based on the application of a bare eye) and 180° (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum.

  19. Phantom limb pain

    MedlinePlus

    Amputation - phantom limb ... Bang MS, Jung SH. Phantom limb pain. In: Frontera, WR, Silver JK, Rizzo TD, eds. Essentials of Physical Medicine and Rehabilitation . 3rd ed. Philadelphia, PA: Elsevier ...

  20. NUNDO: a numerical model of a human torso phantom and its application to effective dose equivalent calculations for astronauts at the ISS.

    PubMed

    Puchalska, Monika; Bilski, Pawel; Berger, Thomas; Hajek, Michael; Horwacik, Tomasz; Körner, Christine; Olko, Pawel; Shurshakov, Vyacheslav; Reitz, Günther

    2014-11-01

    The health effects of cosmic radiation on astronauts need to be precisely quantified and controlled. This task is important not only in perspective of the increasing human presence at the International Space Station (ISS), but also for the preparation of safe human missions beyond low earth orbit. From a radiation protection point of view, the baseline quantity for radiation risk assessment in space is the effective dose equivalent. The present work reports the first successful attempt of the experimental determination of the effective dose equivalent in space, both for extra-vehicular activity (EVA) and intra-vehicular activity (IVA). This was achieved using the anthropomorphic torso phantom RANDO(®) equipped with more than 6,000 passive thermoluminescent detectors and plastic nuclear track detectors, which have been exposed to cosmic radiation inside the European Space Agency MATROSHKA facility both outside and inside the ISS. In order to calculate the effective dose equivalent, a numerical model of the RANDO(®) phantom, based on computer tomography scans of the actual phantom, was developed. It was found that the effective dose equivalent rate during an EVA approaches 700 μSv/d, while during an IVA about 20 % lower values were observed. It is shown that the individual dose based on a personal dosimeter reading for an astronaut during IVA results in an overestimate of the effective dose equivalent of about 15 %, whereas under an EVA conditions the overestimate is more than 200 %. A personal dosemeter can therefore deliver quite good exposure records during IVA, but may overestimate the effective dose equivalent received during an EVA considerably.

  1. Organ/Tissue absorbed doses measured with a human phantom torso in the 9th Shuttle-Mir Mission (STS-91).

    PubMed

    Yasuda, H; Komiyama, T; Fujitaka, K

    1999-09-01

    Organ/Tissue absorbed doses were measured with a life-size human phantom torso in the 9th Shuttle/Mir Mission (STS-91) from June 2 to 12, 1998. This is the first attempt to measure directly organ/tissue doses over a whole human body in space. The absorbed dose was measured by combination of two integrating detectors: thermo- luminescent dosemeter of Mg2SiO4: Tb (TDMS) and plastic nuclear track detector (PNTD). Both detectors were calibrated on ground using high-energy charged-particle beams. The detectors were packed in 59 cases of tissue-equivalent resin; and put into the positions of radiologically important organs and tissues in the phantom. Efficiency reductions of TDMS for high-LET particles were corrected based on the LET-differential particle fluence of space radiation measured with PNTDs. The accumulated absorbed doses during this 9.8-days mission at low-earth orbit (400 km x 51.6 degrees) ranged from 1.6 mGy at colon to 2.6 mGy at bone surface (shoulder) with a variation factor of 1.6. The absorbed doses at some internal organs were higher than the skin dose. This fact is important from the viewpoint of radiological protection for astronauts.

  2. Phantom domain walls

    NASA Astrophysics Data System (ADS)

    Avelino, P. P.; Ferreira, V. M. C.; Menezes, J.; Sousa, L.

    2017-08-01

    We consider a model with two real scalar fields which admits phantom domain wall solutions. We investigate the structure and evolution of these phantom domain walls in an expanding homogeneous and isotropic universe. In particular, we show that the increase of the tension of the domain walls with cosmic time, associated to the evolution of the phantom scalar field, is responsible for an additional damping term in their equations of motion. We describe the macroscopic dynamics of phantom domain walls, showing that extended phantom defects whose tension varies on a cosmological time scale cannot be the dark energy.

  3. Generation of pluripotent stem cells from adult human testis.

    PubMed

    Conrad, Sabine; Renninger, Markus; Hennenlotter, Jörg; Wiesner, Tina; Just, Lothar; Bonin, Michael; Aicher, Wilhelm; Bühring, Hans-Jörg; Mattheus, Ulrich; Mack, Andreas; Wagner, Hans-Joachim; Minger, Stephen; Matzkies, Matthias; Reppel, Michael; Hescheler, Jürgen; Sievert, Karl-Dietrich; Stenzl, Arnulf; Skutella, Thomas

    2008-11-20

    Human primordial germ cells and mouse neonatal and adult germline stem cells are pluripotent and show similar properties to embryonic stem cells. Here we report the successful establishment of human adult germline stem cells derived from spermatogonial cells of adult human testis. Cellular and molecular characterization of these cells revealed many similarities to human embryonic stem cells, and the germline stem cells produced teratomas after transplantation into immunodeficient mice. The human adult germline stem cells differentiated into various types of somatic cells of all three germ layers when grown under conditions used to induce the differentiation of human embryonic stem cells. We conclude that the generation of human adult germline stem cells from testicular biopsies may provide simple and non-controversial access to individual cell-based therapy without the ethical and immunological problems associated with human embryonic stem cells.

  4. 21 CFR 892.1370 - Nuclear anthropomorphic phantom.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear anthropomorphic phantom. 892.1370 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1370 Nuclear anthropomorphic phantom. (a) Identification. A nuclear anthropomorphic phantom is a human tissue facsimile that contains...

  5. Specific activation of operculum 3 (OP3) brain region during provoked tinnitus-related phantom auditory perceptions in humans.

    PubMed

    Job, Agnès; Jacob, Roland; Pons, Yoann; Raynal, Marc; Kossowski, Michel; Gauthier, Jérôme; Lombard, Bertrand; Delon-Martin, Chantal

    2016-03-01

    The phantom sound perception mechanism by which a sound perception occurs without any external sound source is still enigmatic. According to our previous fMRI study, a small region in the parietal operculum 3 was hyperactivated as a function of tinnitus periodicity in subjects with acoustic trauma tinnitus sequelae. This region was localized in the vicinity of neural correlates of middle-ear tympano-ossicular chain movements due to pressure variations. Disturbed proprioceptors are known to trigger illusory perceptions; therefore, we hypothesized that a disturbance of middle-ear proprioceptors may originate phantom sound perceptions. We designed an fMRI study that aimed to stimulate middle-ear proprioceptors by repetitive vibrations using various rates of click trains. In this study, we report that exposure to specific rates of stimuli for a few minutes at comfortable intensity level in healthy subjects distinctly triggered transient tinnitus-like aftereffects. The fMRI neural correlates of the aftereffects were unequivocally localized in the same parietal region as in acoustic trauma tinnitus sufferers. Our results strongly suggest that a middle-ear kinesthetic/proprioceptive illusion exists at the origin of acoustic trauma tinnitus via a somatosensory pathway encompassing the trigeminal system.

  6. Progress in theoretical, experimental, and computational investigations in turbid tissue phantoms and human teeth using laser infrared photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Mandelis, Andreas

    2002-03-01

    This paper reviews and describes the state-of-the-art in the development of frequency-domain infrared photothermal radiometry (FD-PTR) for biomedical and dental applications. The emphasis is placed on the measurement of the optical and thermal properties of tissue-like materials using FD-PTR. A rigorous three-dimensional thermal-wave formulation with three-dimensional diffuse and coherent photon-density-wave sources is presented, and is applied to data from model tissue phantoms and dental enamel samples. The combined theoretical, experimental and computational methodology shows good promise with regard to its analytical ability to measure optical properties of turbid media uniquely, as compared to PPTR, which exhibits uniqueness problems. From data sets obtained with calibrated test phantoms, the reduced optical scattering and absorption coefficients were found to be within 20% and 10%, respectively, from the independently derived values using Mie scattering theory and spectrophotometric measurements. Furthermore, the state-of-the-art and recent developments in applications of laser infrared FD-PTR to dental caries research is described, with examples and histological studies from carious dental tissue. The correlation of PTR signals with modulated dental luminescence is discussed as a very promising potential quantitative methodology for the clinical diagnosis of sub-surface incipient dental caries. The application of the turbid-medium thermal-wave model to the measurement of the optical absorption and scattering coefficients of enamel is also presented.

  7. Estimation of specific absorbed fractions for selected organs due to photons emitted by activity deposited in the human respiratory tract using ICRP/ICRU male voxel phantom in FLUKA.

    PubMed

    Patni, H K; Akar, D K; Nadar, M Y; Ghare, V P; Rao, D D; Sarkar, P K

    2013-01-01

    The ICRP/ICRU adult male reference voxel phantom incorporated in Monte Carlo code FLUKA is used for estimating specific absorbed fractions (SAFs) for photons due to the presence of internal radioactive contamination in the human respiratory tract (RT). The compartments of the RT, i.e. extrathoracic (ET1 and ET2) and thoracic (bronchi, bronchioles, alveolar interstitial) regions, lymph nodes of both regions and lungs are considered as the source organs. The nine organs having high tissue weighting factors such as colon, lungs, stomach wall, breast, testis, urinary bladder, oesophagus, liver and thyroid and the compartments of the RT are considered as target organs. Eleven photon energies in the range of 15 keV to 4 MeV are considered for each source organ and the computed SAF values are presented in the form of tables. For the target organs in the proximity of the source organ including the source organ itself, the SAF values are relatively higher and decrease with increase in energy. As the distance between source and target organ increases, SAF values increase with energy and reach maxima depending on the position of the target organ with respect to the source organ. The SAF values are relatively higher for the target organs with smaller masses. Large deviations are seen in computed SAF values from the existing MIRD phantom data for most of the organs. These estimated SAF values play an important role in the estimation of equivalent dose to various target organs of a worker due to intake by inhalation pathway.

  8. Mathematical phantoms for evaluation of age-specific internal dose

    SciTech Connect

    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.

  9. Latent inhibition in human adults without masking.

    PubMed

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R

    2003-09-01

    Latent inhibition refers to attenuated responding to Cue X observed when the X-outcome pairings are preceded by X-alone presentations. It has proven difficult to obtain in human adults unless the preexposure (X-alone) presentations are embedded within a masking (i.e., distracting) task. The authors hypothesized that the difficulty in obtaining latent inhibition with unmasked tasks is related to the usual training procedures, in which the preexposure and conditioning experiences are separated by a set of instructions. Experiment 1 reports latent inhibition without masking in a task in which preexposure and conditioning occur without interruption. Experiments 2 and 3 demonstrate that this attenuation in responding to target Cue X does not pass a summation test for conditioned inhibition and is context specific, thereby confirming that it is latent inhibition. Experiments 3 and 4 confirm that introducing instructions between preexposure and conditioning disrupts latent inhibition.

  10. Eigenbreasts for statistical breast phantoms

    NASA Astrophysics Data System (ADS)

    Sturgeon, Gregory M.; Tward, Daniel J.; Ketcha, M.; Ratnanather, J. T.; Miller, M. I.; Park, Subok; Segars, W. P.; Lo, Joseph Y.

    2016-03-01

    To facilitate rigorous virtual clinical trials using model observers for breast imaging optimization and evaluation, we demonstrated a method of defining statistical models, based on 177 sets of breast CT patient data, in order to generate tens of thousands of unique digital breast phantoms. In order to separate anatomical texture from variation in breast shape, each training set of breast phantoms were deformed to a consistent atlas compressed geometry. Principal component analysis (PCA) was then performed on the shape-matched breast CT volumes to capture the variation of patient breast textures. PCA decomposes the training set of N breast CT volumes into an N-1-dimensional space of eigenvectors, which we call eigenbreasts. By summing weighted combinations of eigenbreasts, a large ensemble of different breast phantoms can be newly created. Different training sets can be used in eigenbreast analysis for designing basis models to target sub-populations defined by breast characteristics, such as size or density. In this work, we plan to generate ensembles of 30,000 new phantoms based on glandularity for an upcoming virtual trial of lesion detectability in digital breast tomosynthesis. Our method extends our series of digital and physical breast phantoms based on human subject anatomy, providing the capability to generate new, unique ensembles consisting of tens of thousands or more virtual subjects. This work represents an important step towards conducting future virtual trials for tasks-based assessment of breast imaging, where it is vital to have a large ensemble of realistic phantoms for statistical power as well as clinical relevance.

  11. Development of a practical ultrasonic approach for simultaneous measurement of the thickness and the sound speed in human skull bones: a laboratory phantom study.

    PubMed

    Wydra, A; Malyarenko, E; Shapoori, K; Maev, R Gr

    2013-02-21

    The availability of a non-invasive express method for the in vivo measurement of both sound velocity and thickness of the human skull bone would be of great benefit to various transcranial ultrasonic imaging and treatment applications. This paper investigates two ultrasonic methods that measure both parameters and are based on the variable focus technique. All the experiments described in this paper were conducted on specially prepared custom skull bone phantoms, including flat and deformed samples, designed and developed in our laboratory. The first method uses a single immersion 2.25 MHz ultrasonic transducer consecutively focused on the front and back surfaces of the sample. The accuracy and precision of this method are demonstrated via single point measurements on flat samples with and without porosity. The measurement results from a specimen with the randomly curved back surface show the possibility of obtaining the inner profile of the skull bone. The second presented method is a practical modification of the variable focus technique for the linear phased array case. The method was tested on flat and curved skull bone phantoms with and without inner porosity showing higher measurement accuracy and simpler practical realization than its scanning counterpart.

  12. Influence of dentures on SAR in the visible Chinese human head voxel phantom exposed to a mobile phone at 900 and 1800 MHz.

    PubMed

    Yu, Dong; Zhang, Ruoyu; Liu, Qian

    2012-09-01

    To investigate the influence of dentures on electromagnetic energy absorption during the daily use of a mobile phone, a high-resolution head phantom based on the Visible Chinese Human dataset was reconstructed. Simulations on phantoms with various dentures were performed by using the finite-difference time-domain method with a 0.47 wavelength dipole antenna and a mobile phone model as radiation sources at 900 and 1800 MHz. The Specific energy Absorption Rate (SAR) values including 1 and 10 g average SAR values were assessed. When the metallic dental crowns with resonance lengths of approximately one-third to one-half wavelength in the tissue nearby are parallel to the radiation source, up to 121.6% relative enhancement for 1 g average SAR and 17.1% relative enhancement for 10 g average SAR are observed due to the resonance effect in energy absorption. When the radiation sources operate in the normal configuration, the 10 g average SAR values are still in compliance with the basic restrictions established by the Institute of Electrical and Electronic Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP), indicating that the safety limits will not be challenged by the usage of dentures. Copyright © 2012 Wiley Periodicals, Inc.

  13. Instrumentation for investigation of the depth-dose distribution by the Liulin-5 instrument of a human phantom on the Russian segment of ISS for estimation of the radiation risk during long term space flights.

    PubMed

    Semkova, J; Koleva, R; Todorova, G; Kanchev, N; Petrov, V; Shurshakov, V; Tchhernykh, I; Kireeva, S

    2004-01-01

    Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiation doses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year.

  14. Instrumentation for investigation of the depth-dose distribution by the Liulin-5 instrument of a human phantom on the Russian segment of ISS for estimation of the radiation risk during long term space flights

    NASA Technical Reports Server (NTRS)

    Semkova, J.; Koleva, R.; Todorova, G.; Kanchev, N.; Petrov, V.; Shurshakov, V.; Tchhernykh, I.; Kireeva, S.

    2004-01-01

    Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiation doses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  15. Instrumentation for investigation of the depth-dose distribution by the Liulin-5 instrument of a human phantom on the Russian segment of ISS for estimation of the radiation risk during long term space flights

    NASA Technical Reports Server (NTRS)

    Semkova, J.; Koleva, R.; Todorova, G.; Kanchev, N.; Petrov, V.; Shurshakov, V.; Tchhernykh, I.; Kireeva, S.

    2004-01-01

    Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiation doses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  16. Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation.

    PubMed

    Sun, Wenjuan; Jia, Xianghong; Xie, Tianwu; Xu, Feng; Liu, Qian

    2013-03-01

    With the rapid development of China's space industry, the importance of radiation protection is increasingly prominent. To provide relevant dose data, we first developed the Visible Chinese Human adult Female (VCH-F) phantom, and performed further modifications to generate the VCH-F Astronaut (VCH-FA) phantom, incorporating statistical body characteristics data from the first batch of Chinese female astronauts as well as reference organ mass data from the International Commission on Radiological Protection (ICRP; both within 1% relative error). Based on cryosection images, the original phantom was constructed via Non-Uniform Rational B-Spline (NURBS) boundary surfaces to strengthen the deformability for fitting the body parameters of Chinese female astronauts. The VCH-FA phantom was voxelized at a resolution of 2 × 2 × 4 mm(3)for radioactive particle transport simulations from isotropic protons with energies of 5000-10 000 MeV in Monte Carlo N-Particle eXtended (MCNPX) code. To investigate discrepancies caused by anatomical variations and other factors, the obtained doses were compared with corresponding values from other phantoms and sex-averaged doses. Dose differences were observed among phantom calculation results, especially for effective dose with low-energy protons. Local skin thickness shifts the breast dose curve toward high energy, but has little impact on inner organs. Under a shielding layer, organ dose reduction is greater for skin than for other organs. The calculated skin dose per day closely approximates measurement data obtained in low-Earth orbit (LEO).

  17. Image based Monte Carlo Modeling for Computational Phantom

    NASA Astrophysics Data System (ADS)

    Cheng, Mengyun; Wang, Wen; Zhao, Kai; Fan, Yanchang; Long, Pengcheng; Wu, Yican

    2014-06-01

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

  18. Simulation Of Human Body Radiation Using Phantom Model On Beam lowbar nrc And Verification On Dosxyz lowbar nrc

    SciTech Connect

    Adiba, Amalia Istiqlali; Haryanto, Freddy

    2010-12-23

    The optimum dose can be produced by measuring and analysis of the dose distribution from the source. The energy of the source must be maximum for the target cell, and must minimum for the tissues that surround the target cell. In this study, the phantom model has a cylindrical shape with 20 cm radius and 19 cm depth. The calculation is done where photon beam energy is 6 MeV with 3 different radius beam; 0.3 cm, 5 cm, and 15 cm. The verification was done with a model cube film which was arranged by element voxel which made by Mylar and Ag. The results of this simulation shows the difference dose distribution for radius beam 0.5 cm, 3 cm, and 15 cm that is caused by particle density and penumbra effect. And for all beam radiuses, the maximum dose (100%) happens in 1.5-2 mm depth from film model.

  19. SU-E-T-399: Evaluation of Selection Criteria for Computational Human Phantoms for Use in Out-Of-Field Organ Dosimetry for Radiotherapy Patients

    SciTech Connect

    Pelletier, C; Jung, J; Lee, C; Pyakuryal, A; Lee, C; Kim, J

    2015-06-15

    Purpose: To quantify the dosimetric uncertainty due to organ position errors when using height and weight as phantom selection criteria in the UF/NCI Hybrid Phantom Library for the purpose of out-of-field organ dose reconstruction. Methods: Four diagnostic patient CT images were used to create 7-field IMRT plans. For each patient, dose to the liver, right lung, and left lung were calculated using the XVMC Monte Carlo code. These doses were taken to be the ground truth. For each patient, the phantom with the most closely matching height and weight was selected from the body size dependent phantom library. The patient plans were then transferred to the computational phantoms and organ doses were recalculated. Each plan was also run on 4 additional phantoms with reference heights and or weights. Maximum and mean doses for the three organs were computed, and the DVHs were extracted and compared. One sample t-tests were performed to compare the accuracy of the height and weight matched phantoms against the additional phantoms in regards to both maximum and mean dose. Results: For one of the patients, the height and weight matched phantom yielded the most accurate results across all three organs for both maximum and mean doses. For two additional patients, the matched phantom yielded the best match for one organ only. In 13 of the 24 cases, the matched phantom yielded better results than the average of the other four phantoms, though the results were only statistically significant at the .05 level for three cases. Conclusion: Using height and weight matched phantoms does yield better results in regards to out-of-field dosimetry than using average phantoms. Height and weight appear to be moderately good selection criteria, though this selection criteria failed to yield any better results for one patient.

  20. WE-EF-303-06: Feasibility of PET Image-Based On-Line Proton Beam-Range Verification with Simulated Uniform Phantom and Human Brain Studies

    SciTech Connect

    Lou, K; Sun, X; Zhu, X; Grosshans, D; Clark, J; Shao, Y

    2015-06-15

    Purpose: To study the feasibility of clinical on-line proton beam range verification with PET imaging Methods: We simulated a 179.2-MeV proton beam with 5-mm diameter irradiating a PMMA phantom of human brain size, which was then imaged by a brain PET with 300*300*100-mm{sup 3} FOV and different system sensitivities and spatial resolutions. We calculated the mean and standard deviation of positron activity range (AR) from reconstructed PET images, with respect to different data acquisition times (from 5 sec to 300 sec with 5-sec step). We also developed a technique, “Smoothed Maximum Value (SMV)”, to improve AR measurement under a given dose. Furthermore, we simulated a human brain irradiated by a 110-MeV proton beam of 50-mm diameter with 0.3-Gy dose at Bragg peak and imaged by the above PET system with 40% system sensitivity at the center of FOV and 1.7-mm spatial resolution. Results: MC Simulations on the PMMA phantom showed that, regardless of PET system sensitivities and spatial resolutions, the accuracy and precision of AR were proportional to the reciprocal of the square root of image count if image smoothing was not applied. With image smoothing or SMV method, the accuracy and precision could be substantially improved. For a cylindrical PMMA phantom (200 mm diameter and 290 mm long), the accuracy and precision of AR measurement could reach 1.0 and 1.7 mm, with 100-sec data acquired by the brain PET. The study with a human brain showed it was feasible to achieve sub-millimeter accuracy and precision of AR measurement with acquisition time within 60 sec. Conclusion: This study established the relationship between count statistics and the accuracy and precision of activity-range verification. It showed the feasibility of clinical on-line BR verification with high-performance PET systems and improved AR measurement techniques. Cancer Prevention and Research Institute of Texas grant RP120326, NIH grant R21CA187717, The Cancer Center Support (Core) Grant CA

  1. Wavelet-based resolution recovery using an anatomical prior provides quantitative recovery for human population phantom PET [11C]raclopride data

    NASA Astrophysics Data System (ADS)

    Shidahara, M.; Tsoumpas, C.; McGinnity, C. J.; Kato, T.; Tamura, H.; Hammers, A.; Watabe, H.; Turkheimer, F. E.

    2012-05-01

    The objective of this study was to evaluate a resolution recovery (RR) method using a variety of simulated human brain [11C]raclopride positron emission tomography (PET) images. Simulated datasets of 15 numerical human phantoms were processed by a wavelet-based RR method using an anatomical prior. The anatomical prior was in the form of a hybrid segmented atlas, which combined an atlas for anatomical labelling and a PET image for functional labelling of each anatomical structure. We applied RR to both 60 min static and dynamic PET images. Recovery was quantified in 84 regions, comparing the typical ‘true’ value for the simulation, as obtained in normal subjects, simulated and RR PET images. The radioactivity concentration in the white matter, striatum and other cortical regions was successfully recovered for the 60 min static image of all 15 human phantoms; the dependence of the solution on accurate anatomical information was demonstrated by the difficulty of the technique to retrieve the subthalamic nuclei due to mismatch between the two atlases used for data simulation and recovery. Structural and functional synergy for resolution recovery (SFS-RR) improved quantification in the caudate and putamen, the main regions of interest, from -30.1% and -26.2% to -17.6% and -15.1%, respectively, for the 60 min static image and from -51.4% and -38.3% to -27.6% and -20.3% for the binding potential (BPND) image, respectively. The proposed methodology proved effective in the RR of small structures from brain [11C]raclopride PET images. The improvement is consistent across the anatomical variability of a simulated population as long as accurate anatomical segmentations are provided.

  2. Astrocitary niches in human adult medulla oblongata.

    PubMed

    Rusu, Mugurel Constantin; Dermengiu, Dan; Loreto, Carla; Motoc, Andrei Gheorghe Marius; Pop, Elena

    2013-04-01

    Astrocytes are considered as neuromodulators of the CNS. Whereas experimental studies on astrocitary functions are gaining importance, the anatomy of the astrocitary niches in the human CNS has been overlooked. The study was performed on the brainstem of 10 adult cadavers. We aimed to determine astrocitary niches in the human medulla oblongata using immunohistochemical labeling with vimentin and also CD34 immunostaining to accurately diagnose associated microvessels. Niches rich in astrocytes were identified as follows: (a) the superficial layer of astrocytes, ventral and ventrolateral, in the rostral medulla oblongata; (b) the median raphe; (c) medullary nuclei: arcuate nucleus, area postrema, nucleus of the solitary tract; (d) the subependymal zone (SEZ, caudal medulla) and subventricular zone (SVZ, rostral medulla). Astrocytes were scarce in the ventrolateral medulla, and mostly present within the pyramidal tract and the olivary nucleus. Apart from the SEZ and SVZ, the brainstem niches of astrocytes mostly overlap those regions known to perform roles as central respiratory chemoreceptors. The astrocytes of the SEZ and SVZ, which are known as stem cell niches, are related to an increased microvascular density.

  3. "Phantom" carpal tunnel syndrome.

    PubMed

    Braverman, D L; Root, B C

    1997-10-01

    Phantom sensation is ubiquitous among persons who have had amputation; however, if it develops into phantom pain, a thorough clinical investigation must ensue. We illustrate this with the case of a 49-year-old woman, 14 years after traumatic amputation of her left 2nd through 5th fingers, and 10 years after traumatic left transfemoral amputation. She had had phantom sensation in her absent fingers for years and developed progressive pain in her phantom fingers 3 months before presentation. Nerve conduction study revealed a high-normal distal motor latency of the left median nerve and a positive Bactrian test (sensitivity 87%). She was diagnosed with "phantom" carpal tunnel syndrome and treated with a resting wrist splint, decreased weight bearing on the left upper limb, and two corticosteroid carpal tunnel injections with marked improvement. Clinicians should recognize that phantom pain may be referred from a more proximal region and may be amenable to conservative management.

  4. Have you got any cholesterol? Adults' views of human nutrition

    NASA Astrophysics Data System (ADS)

    Schibeci, Renato; Wong, Khoon Yoong

    1994-12-01

    The general aim of our human nutrition project is to develop a health education model grounded in ‘everyday’ or ‘situated’ cognition (Hennessey, 1993). In 1993, we began pilot work to document adult understanding of human nutrition. We used a HyperCard stack as the basis for a series of interviews with 50 adults (25 university students, and 25 adults from offcampus). The interviews were transcribed and analysed using the NUDIST computer program. A summary of the views of these 50 adults on selected aspects of human nutrition is presented in this paper.

  5. [Phantom limb pain].

    PubMed

    Steffen, Peter

    2006-06-01

    Almost everyone who has amputated a limb will experience a phantom limb. They have the vivid impression, that the limb is still present. 60 to 70% of these amputees will suffer from phantom limb pain. The present paper gives an overview of the incidence and the characteristics of the so called "post amputation syndrome". Possible mechanism of this phenomena are presented, including peripheral, spinal, and central theories. Treatment of phantom limb pain is sometimes very difficult. It includes drug therapy, psychological therapy, physiotherapy as well as the prevention of phantom limb pain with regional analgesia techniques.

  6. Adult Education & Human Resource Development: Overlapping and Disparate Fields

    ERIC Educational Resources Information Center

    Watkins, Karen E.; Marsick, Victoria J.

    2014-01-01

    Adult education and human resource development as fields of practice and study share some roots in common but have grown in different directions in their histories. Adult education's roots focused initially on citizenship for a democratic society, whereas human resource development's roots are in performance at work. While they have…

  7. Adult Education & Human Resource Development: Overlapping and Disparate Fields

    ERIC Educational Resources Information Center

    Watkins, Karen E.; Marsick, Victoria J.

    2014-01-01

    Adult education and human resource development as fields of practice and study share some roots in common but have grown in different directions in their histories. Adult education's roots focused initially on citizenship for a democratic society, whereas human resource development's roots are in performance at work. While they have…

  8. Encephalitis-Associated Human Metapneumovirus Pneumonia in Adult, Australia

    PubMed Central

    Mateevici, Cristina; Lin, Belinda; Chandra, Ronil V.; Chong, Victor H.T.

    2015-01-01

    Human metapneumovirus pneumonia, most commonly found in children, was diagnosed in an adult with encephalitis. This case suggests that testing for human metapneumovirus RNA in nasopharyngeal aspirate and cerebrospinal fluid samples should be considered in adults with encephalitis who have a preceding respiratory infection, PMID:26488420

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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 crosstalk in

  10. Influence of a fat layer on the near infrared spectra of human muscle: quantitative analysis based on two-layered Monte Carlo simulations and phantom experiments

    NASA Technical Reports Server (NTRS)

    Yang, Ye; Soyemi, Olusola O.; Landry, Michelle R.; Soller, Babs R.

    2005-01-01

    The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared (NIR) region is studied by Monte Carlo simulations of a two-layer structure and with phantom experiments. A polynomial relationship was established between the fat thickness and the detected diffuse reflectance. The influence of a range of optical coefficients (absorption and reduced scattering) for fat and muscle over the known range of human physiological values was also investigated. Subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm. A method was proposed to correct the fat thickness influence. c2005 Optical Society of America.

  11. Influence of a fat layer on the near infrared spectra of human muscle: quantitative analysis based on two-layered Monte Carlo simulations and phantom experiments

    NASA Technical Reports Server (NTRS)

    Yang, Ye; Soyemi, Olusola O.; Landry, Michelle R.; Soller, Babs R.

    2005-01-01

    The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared (NIR) region is studied by Monte Carlo simulations of a two-layer structure and with phantom experiments. A polynomial relationship was established between the fat thickness and the detected diffuse reflectance. The influence of a range of optical coefficients (absorption and reduced scattering) for fat and muscle over the known range of human physiological values was also investigated. Subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm. A method was proposed to correct the fat thickness influence. c2005 Optical Society of America.

  12. Adult human brain cell culture for neuroscience research.

    PubMed

    Gibbons, Hannah M; Dragunow, Mike

    2010-06-01

    Studies of the brain have progressed enormously through the use of in vivo and in vitro non-human models. However, it is unlikely such studies alone will unravel the complexities of the human brain and so far no neuroprotective treatment developed in animals has worked in humans. In this review we discuss the use of adult human brain cell culture methods in brain research to unravel the biology of the normal and diseased human brain. The advantages of using adult human brain cells as tools to study human brain function from both historical and future perspectives are discussed. In particular, studies using dissociated cultures of adult human microglia, astrocytes, oligodendrocytes and neurons are described and the applications of these types of study are evaluated. Alternative sources of human brain cells such as adult neural stem cells, induced pluripotent stem cells and slice cultures of adult human brain tissue are also reviewed. These adult human brain cell culture methods could benefit basic research and more importantly, facilitate the translation of basic neuroscience research to the clinic for the treatment of brain disorders.

  13. Attracting Adult Learners to Humanities Courses. Final Report.

    ERIC Educational Resources Information Center

    American Association of Community and Junior Colleges, Washington, DC.

    A round table discussion among community college presidents and humanities faculty on how to encourage adults to enroll in humanities courses resulted in eleven recommendations. These included experimentation in how to access community interests in humanities courses, the integration of humanities with occupational training to help people deal…

  14. The dynamics of adult neurogenesis in human hippocampus

    PubMed Central

    Ihunwo, Amadi O.; Tembo, Lackson H.; Dzamalala, Charles

    2016-01-01

    The phenomenon of adult neurogenesis is now an accepted occurrence in mammals and also in humans. At least two discrete places house stem cells for generation of neurons in adult brain. These are olfactory system and the hippocampus. In animals, newly generated neurons have been directly or indirectly demonstrated to generate a significant amount of new neurons to have a functional role. However, the data in humans on the extent of this process is still scanty and such as difficult to comprehend its functional role in humans. This paper explores the available data on as extent of adult hippocampal neurogenesis in humans and makes comparison to animal data. PMID:28197172

  15. Development of a percutaneous optical imaging system for tracking vascular gene expression: a feasibility study using human tissuelike phantoms

    NASA Astrophysics Data System (ADS)

    Kar, Sourav K.; Kumar, Ananda; Yang, Xiaoming

    2004-05-01

    Noninvasive tracking of vascular gene delivery and expression forms an important part of successfully implementing vascular gene therapy methods for the treatment of atherosclerosis and various cardiovascular disorders. While ultrasound and MR imaging have shown promise in the monitoring of gene delivery to the vasculatures, optical imaging has shown promise for tracking gene expression. Optical imaging using bioreporter genes like Green Fluorescent Protein (GFP), Red Fluorescent Protein (RFP) and Luciferase to track and localize the therapeutic gene have helped provide an in vivo detection method of the process. The usage of GFP and RFP entails the detection of the fluorescent signal emitted by them on excitation with light of appropriate wavelength. We have developed a novel percutaneous optical imaging system that may be used for in vivo tracking vascular fluorescent gene expression in deep-seated vessels. It is based on the detection of the fluorescent signal emitted from GFP tagged cells. This phantom study was carried out to investigate the performance of the optical imaging system and gain insights into its performance record and study improvisation possibilities.

  16. Phantom Torso model

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Phantom Torso is a tissue-muscle plastic anatomical model of a torso and head. It contains over 350 radiation measuring devices to calculate the radiation that penetrates internal organs in space travel. The Phantom Torso is one of three radiation experiments in Expedition Two including the Borner Ball Neutron Detector and Dosimetric Mapping.

  17. Adult Human Neurogenesis: From Microscopy to Magnetic Resonance Imaging

    PubMed Central

    Sierra, Amanda; Encinas, Juan M.; Maletic-Savatic, Mirjana

    2011-01-01

    Neural stem cells reside in well-defined areas of the adult human brain and are capable of generating new neurons throughout the life span. In rodents, it is well established that the new born neurons are involved in olfaction as well as in certain forms of memory and learning. In humans, the functional relevance of adult human neurogenesis is being investigated, in particular its implication in the etiopathology of a variety of brain disorders. Adult neurogenesis in the human brain was discovered by utilizing methodologies directly imported from the rodent research, such as immunohistological detection of proliferation and cell-type specific biomarkers in postmortem or biopsy tissue. However, in the vast majority of cases, these methods do not support longitudinal studies; thus, the capacity of the putative stem cells to form new neurons under different disease conditions cannot be tested. More recently, new technologies have been specifically developed for the detection and quantification of neural stem cells in the living human brain. These technologies rely on the use of magnetic resonance imaging, available in hospitals worldwide. Although they require further validation in rodents and primates, these new methods hold the potential to test the contribution of adult human neurogenesis to brain function in both health and disease. This review reports on the current knowledge on adult human neurogenesis. We first review the different methods available to assess human neurogenesis, both ex vivo and in vivo and then appraise the changes of adult neurogenesis in human diseases. PMID:21519376

  18. Adult human neurogenesis: from microscopy to magnetic resonance imaging.

    PubMed

    Sierra, Amanda; Encinas, Juan M; Maletic-Savatic, Mirjana

    2011-01-01

    Neural stem cells reside in well-defined areas of the adult human brain and are capable of generating new neurons throughout the life span. In rodents, it is well established that the new born neurons are involved in olfaction as well as in certain forms of memory and learning. In humans, the functional relevance of adult human neurogenesis is being investigated, in particular its implication in the etiopathology of a variety of brain disorders. Adult neurogenesis in the human brain was discovered by utilizing methodologies directly imported from the rodent research, such as immunohistological detection of proliferation and cell-type specific biomarkers in postmortem or biopsy tissue. However, in the vast majority of cases, these methods do not support longitudinal studies; thus, the capacity of the putative stem cells to form new neurons under different disease conditions cannot be tested. More recently, new technologies have been specifically developed for the detection and quantification of neural stem cells in the living human brain. These technologies rely on the use of magnetic resonance imaging, available in hospitals worldwide. Although they require further validation in rodents and primates, these new methods hold the potential to test the contribution of adult human neurogenesis to brain function in both health and disease. This review reports on the current knowledge on adult human neurogenesis. We first review the different methods available to assess human neurogenesis, both ex vivo and in vivo and then appraise the changes of adult neurogenesis in human diseases.

  19. Region of interest (ROI) computed tomography (CT): Comparison with full field of view (FFOV) and truncated CT for a human head phantom.

    PubMed

    Chityala, R; Hoffmann, K R; Rudin, S; Bednarek, D R

    2005-01-01

    Cone-beam CT reconstruction can be performed at lower integral dose, by using a non-uniform beam filter between the x-ray source and the patient to obtain good image quality within an ROI with minimal artifacts. To evaluate the method, a human head phantom was placed on a rotary stage. Cone-beam projection images of the phantom were obtained with and without an ROI filter (dose reduction factor ~7). A mapping function was established to equalize the intensity outside the ROI (to compensate for the attenuation by the filter) to the intensity inside by assuming that those features lying both inside and outside very close to the edge of the ROI are the same. Reconstructed images were obtained using equalized projection images for 2 cases: one in which the outside region was smoothed using an averaging filter and the other with no smoothing outside. In addition, a third case was simulated by calculating the average pixel value inside the ROI for each image and assigning this value to all pixels outside the ROI for that image. The images were then back projected using a Feldkamp algorithm. We found that the three cases yield results inside the ROI comparable to those obtained using FFOV projections. In addition, the ROI filter reconstruction with smoothing provides image information outside the ROI comparable to the FFOV reconstruction. CT using an ROI filter provides a means to reconstruct reliable 3D for a volume of interest with greatly reduced integral dose compared to FFOV projections and with minimal artifacts.

  20. Hybrid computational phantoms of the 15-year male and female adolescent: Applications to CT organ dosimetry for patients of variable morphometry

    SciTech Connect

    Lee, Choonsik; Lodwick, Daniel; Williams, Jonathan L.; Bolch, Wesley E.

    2008-06-15

    Currently, two classes of the computational phantoms have been developed for dosimetry calculation: (1) stylized (or mathematical) and (2) voxel (or tomographic) phantoms describing human anatomy through mathematical surface equations and three-dimensional labeled voxel matrices, respectively. Mathematical surface equations in stylized phantoms provide flexibility in phantom design and alteration, but the resulting anatomical description is, in many cases, not very realistic. Voxel phantoms display far better anatomical realism, but they are limited in terms of their ability to alter organ shape, position, and depth, as well as body posture. A new class of computational phantoms - called hybrid phantoms - takes advantage of the best features of stylized and voxel phantoms - flexibility and anatomical realism, respectively. In the current study, hybrid computational phantoms representing reference 15-year male and female body anatomy and anthropometry are presented. For the male phantom, organ contours were extracted from the University of Florida (UF) 14-year series B male voxel phantom, while for the female phantom, original computed tomography (CT) data from two 14-year female patients were used. Polygon mesh models for the major organs and tissues were reconstructed for nonuniform rational B-spline (NURBS) surface modeling. The resulting NURBS/polygon mesh models representing body contour and internal anatomy were matched to anthropometric data and reference organ mass data provided by the Centers for Disease Control and Prevention (CDC) and the International Commission on Radiation Protection (ICRP), respectively. Finally, two hybrid 15-year male and female phantoms were completed where a total of eight anthropometric data categories were matched to standard values within 4% and organ masses matched to ICRP data within 1% with the exception of total skin. To highlight the flexibility of the hybrid phantoms, 10th and 90th weight percentile 15-year male and

  1. Assessment of individual organ doses in a realistic human phantom from neutron and gamma stimulated spectroscopy of the breast and liver.

    PubMed

    Belley, Matthew D; Segars, William Paul; Kapadia, Anuj J

    2014-06-01

    Understanding the radiation dose to a patient is essential when considering the use of an ionizing diagnostic imaging test for clinical diagnosis and screening. Using Monte Carlo simulations, the authors estimated the three-dimensional organ-dose distribution from neutron and gamma irradiation of the male liver, female liver, and female breasts for neutron- and gamma-stimulated spectroscopic imaging. Monte Carlo simulations were developed using the Geant4 GATE application and a voxelized XCAT human phantom. A male and a female whole body XCAT phantom was voxelized into 256 × 256 × 600 voxels (3.125 × 3.125 × 3.125 mm(3)). A monoenergetic rectangular beam of 5.0 MeV neutrons or 7.0 MeV photons was made incident on a 2 cm thick slice of the phantom. The beam was rotated at eight different angles around the phantom ranging from 0° to 180°. Absorbed dose was calculated for each individual organ in the body and dose volume histograms were computed to analyze the absolute and relative doses in each organ. The neutron irradiations of the liver showed the highest organ dose absorption in the liver, with appreciably lower doses in other proximal organs. The dose distribution within the irradiated slice exhibited substantial attenuation with increasing depth along the beam path, attenuating to ~15% of the maximum value at the beam exit side. The gamma irradiation of the liver imparted the highest organ dose to the stomach wall. The dose distribution from the gammas showed a region of dose buildup at the beam entrance, followed by a relatively uniform dose distribution to all of the deep tissue structures, attenuating to ~75% of the maximum value at the beam exit side. For the breast scans, both the neutron and gamma irradiation registered maximum organ doses in the breasts, with all other organs receiving less than 1% of the breast dose. Effective doses ranged from 0.22 to 0.37 mSv for the neutron scans and 41 to 66 mSv for the gamma scans. Neutron and gamma

  2. Assessment of individual organ doses in a realistic human phantom from neutron and gamma stimulated spectroscopy of the breast and liver

    SciTech Connect

    Belley, Matthew D.; Segars, William Paul; Kapadia, Anuj J.

    2014-06-15

    Purpose: Understanding the radiation dose to a patient is essential when considering the use of an ionizing diagnostic imaging test for clinical diagnosis and screening. Using Monte Carlo simulations, the authors estimated the three-dimensional organ-dose distribution from neutron and gamma irradiation of the male liver, female liver, and female breasts for neutron- and gamma-stimulated spectroscopic imaging. Methods: Monte Carlo simulations were developed using the Geant4 GATE application and a voxelized XCAT human phantom. A male and a female whole body XCAT phantom was voxelized into 256 × 256 × 600 voxels (3.125 × 3.125 × 3.125 mm{sup 3}). A monoenergetic rectangular beam of 5.0 MeV neutrons or 7.0 MeV photons was made incident on a 2 cm thick slice of the phantom. The beam was rotated at eight different angles around the phantom ranging from 0° to 180°. Absorbed dose was calculated for each individual organ in the body and dose volume histograms were computed to analyze the absolute and relative doses in each organ. Results: The neutron irradiations of the liver showed the highest organ dose absorption in the liver, with appreciably lower doses in other proximal organs. The dose distribution within the irradiated slice exhibited substantial attenuation with increasing depth along the beam path, attenuating to ∼15% of the maximum value at the beam exit side. The gamma irradiation of the liver imparted the highest organ dose to the stomach wall. The dose distribution from the gammas showed a region of dose buildup at the beam entrance, followed by a relatively uniform dose distribution to all of the deep tissue structures, attenuating to ∼75% of the maximum value at the beam exit side. For the breast scans, both the neutron and gamma irradiation registered maximum organ doses in the breasts, with all other organs receiving less than 1% of the breast dose. Effective doses ranged from 0.22 to 0.37 mSv for the neutron scans and 41 to 66 mSv for the gamma

  3. Assessment of individual organ doses in a realistic human phantom from neutron and gamma stimulated spectroscopy of the breast and liver

    PubMed Central

    Belley, Matthew D.; Segars, William Paul; Kapadia, Anuj J.

    2014-01-01

    Purpose: Understanding the radiation dose to a patient is essential when considering the use of an ionizing diagnostic imaging test for clinical diagnosis and screening. Using Monte Carlo simulations, the authors estimated the three-dimensional organ-dose distribution from neutron and gamma irradiation of the male liver, female liver, and female breasts for neutron- and gamma-stimulated spectroscopic imaging. Methods: Monte Carlo simulations were developed using the Geant4 GATE application and a voxelized XCAT human phantom. A male and a female whole body XCAT phantom was voxelized into 256 × 256 × 600 voxels (3.125 × 3.125 × 3.125 mm3). A monoenergetic rectangular beam of 5.0 MeV neutrons or 7.0 MeV photons was made incident on a 2 cm thick slice of the phantom. The beam was rotated at eight different angles around the phantom ranging from 0° to 180°. Absorbed dose was calculated for each individual organ in the body and dose volume histograms were computed to analyze the absolute and relative doses in each organ. Results: The neutron irradiations of the liver showed the highest organ dose absorption in the liver, with appreciably lower doses in other proximal organs. The dose distribution within the irradiated slice exhibited substantial attenuation with increasing depth along the beam path, attenuating to ∼15% of the maximum value at the beam exit side. The gamma irradiation of the liver imparted the highest organ dose to the stomach wall. The dose distribution from the gammas showed a region of dose buildup at the beam entrance, followed by a relatively uniform dose distribution to all of the deep tissue structures, attenuating to ∼75% of the maximum value at the beam exit side. For the breast scans, both the neutron and gamma irradiation registered maximum organ doses in the breasts, with all other organs receiving less than 1% of the breast dose. Effective doses ranged from 0.22 to 0.37 mSv for the neutron scans and 41 to 66 mSv for the gamma scans

  4. Developing Resourceful Humans. Adult Education within the Economic Context.

    ERIC Educational Resources Information Center

    Burton, Lynn Elen, Ed.

    This book, which explores the shifting paradigm from human resource development to developing resourceful humans, establishes the historical position of adult education within the economic context, discusses human capital propositions, and examines the learning dimensions of economic and educational change. The following chapters are included:…

  5. Humanizing Adult Education Research: Five Stories from the 1930's.

    ERIC Educational Resources Information Center

    Hilton, Ronald

    Taken from the author's doctoral dissertation, this award-winning monograph describes a method for humanizing educational research in adult education and provides five stories of adult education efforts in the 1930's as examples of such research. The method described suggests valuing qualitative data as much as quantitative in the field of…

  6. Adult Literacy Education and Human Rights: A View from Afghanistan

    ERIC Educational Resources Information Center

    Andersen, Susan M.; Kooij, Christina S.

    2007-01-01

    In this article, we argue that adult literacy as part of international development is an issue of both human rights and women's rights. We explore this by presenting a case study of the effects of one innovative adult literacy program in Afghanistan that places men and women, as well as various ethnicities, together in the same classroom as…

  7. Anthropomorphic 1H MRS head phantom.

    PubMed

    Rice, J R; Milbrandt, R H; Madsen, E L; Frank, G R; Boote, E J; Blechinger, J C

    1998-07-01

    An anthropomorphic 1H MRS head phantom has been developed which mimics the in vivo structure, metabolite concentrations, and relaxation times (for both water and metabolites) of human brain tissue. Different brain regions and two tumor types, fluid-containing ventricles, and air-filled sinus, and subcutaneous fat are all simulated. The main tissue-mimicking materials are gelatin/agar mixtures with metabolites and several other ingredients added. Their composition and method of production are thoroughly described. T1's and T2's of water in the phantom are very close to in vivo values, and metabolite T1's and T2's are considerably more realistic than those in aqueous solutions. Spectra and relaxation times for the pig brain were also acquired and compare well with those of the phantom. The realistic properties of this phantom should be useful for testing spectral quantitation and localization.

  8. Evaluating accuracy of structural geometry by DXA methods with an anthropometric proximal femur phantom.

    PubMed

    Khoo, B C C; Beck, T J; Brown, K; Price, R I

    2013-09-01

    DXA-derived bone structural geometry has been reported extensively but lacks an accuracy standard. In this study, we describe a novel anthropometric structural geometry phantom that simulates the proximal femur for use in assessing accuracy of geometry measurements by DXA or other X-ray methods. The phantom consists of seven different interchangeable neck modules with geometries that span the range of dimensions in an adult human proximal femur, including those representing osteoporosis. Ten repeated hip scans of each neck module using two current DXA scanner models were performed without repositioning. After scanner specific calibration, hip structure analysis was used to derive structural geometry. Scanner performance was similar for the two manufacturers. DXA-derived HSA geometric measurements were highly correlated with values derived directly from phantom geometry and position; R² between DXA and phantom measures were greater than 94% for all parameters, while precision error ranged between 0.3 and 3.9%. Despite high R² there were some systematic geometry errors for both scanners that were small for outer diameter, but increasing with complexity of geometrical parameter; e.g. buckling ratio. In summary, the anthropometric phantom and its fabrication concept were shown to be appropriate for evaluating proximal femoral structural geometry in two different DXA systems.

  9. Pipe Phantoms With Applications in Molecular Imaging and System Characterization.

    PubMed

    Wang, Shiying; Herbst, Elizabeth B; Pye, Stephen D; Moran, Carmel M; Hossack, John A

    2017-01-01

    Pipe (vessel) phantoms mimicking human tissue and blood flow are widely used for cardiovascular related research in medical ultrasound. Pipe phantom studies require the development of materials and liquids that match the acoustic properties of soft tissue, blood vessel wall, and blood. Over recent years, pipe phantoms have been developed to mimic the molecular properties of the simulated blood vessels. In this paper, the design, construction, and functionalization of pipe phantoms are introduced and validated for applications in molecular imaging and ultrasound imaging system characterization. There are three major types of pipe phantoms introduced: 1) a gelatin-based pipe phantom; 2) a polydimethylsiloxane-based pipe phantom; and 3) the "Edinburgh pipe phantom." These phantoms may be used in the validation and assessment of the dynamics of microbubble-based contrast agents and, in the case of a small diameter tube phantom, for assessing imaging system spatial resolution/contrast performance. The materials and procedures required to address each of the phantoms are described.

  10. Lung pair phantom

    DOEpatents

    Olsen, Peter C.; Gordon, N. Ross; Simmons, Kevin L.

    1993-01-01

    The present invention is a material and method of making the material that exhibits improved radiation attenuation simulation of real lungs, i.e., an "authentic lung tissue" or ALT phantom. Specifically, the ALT phantom is a two-part polyurethane medium density foam mixed with calcium carbonate, potassium carbonate if needed for K-40 background, lanthanum nitrate, acetone, and a nitrate or chloride form of a radionuclide. This formulation is found to closely match chemical composition and linear attenuation of real lungs. The ALT phantom material is made according to established procedures but without adding foaming agents or preparing thixotropic concentrate and with a modification for ensuring uniformity of density of the ALT phantom that is necessary for accurate simulation. The modification is that the polyurethane chemicals are mixed at a low temperature prior to pouring the polyurethane mixture into the mold.

  11. Lung pair phantom

    DOEpatents

    Olsen, P.C.; Gordon, N.R.; Simmons, K.L.

    1993-11-30

    The present invention is a material and method of making the material that exhibits improved radiation attenuation simulation of real lungs, i.e., an ``authentic lung tissue`` or ALT phantom. Specifically, the ALT phantom is a two-part polyurethane medium density foam mixed with calcium carbonate, potassium carbonate if needed for K-40 background, lanthanum nitrate, acetone, and a nitrate or chloride form of a radionuclide. This formulation is found to closely match chemical composition and linear attenuation of real lungs. The ALT phantom material is made according to established procedures but without adding foaming agents or preparing thixotropic concentrate and with a modification for ensuring uniformity of density of the ALT phantom that is necessary for accurate simulation. The modification is that the polyurethane chemicals are mixed at a low temperature prior to pouring the polyurethane mixture into the mold.

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

    NASA Astrophysics Data System (ADS)

    Anderson-Jackson, LaTecia D.

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

  13. SU-E-T-117: Dose to Organs Outside of CT Scan Range- Monte Carlo and Hybrid Phantom Approach

    SciTech Connect

    Pelletier, C; Jung, J; Lee, C; Kim, J; Lee, C

    2014-06-01

    Purpose: Epidemiological study of second cancer risk for cancer survivors often requires the dose to normal tissues located outside the anatomy covered by radiological imaging, which is usually limited to tumor and organs at risk. We have investigated the feasibility of using whole body computational human phantoms for estimating out-of-field organ doses for patients treated by Intensity Modulated Radiation Therapy (IMRT). Methods: Identical 7-field IMRT prostate plans were performed using X-ray Voxel Monte Carlo (XVMC), a radiotherapy-specific Monte Carlo transport code, on the computed tomography (CT) images of the torso of an adult male patient (175 cm height, 66 kg weight) and an adult male hybrid computational phantom with the equivalent body size. Dose to the liver, right lung, and left lung were calculated and compared. Results: Considerable differences are seen between the doses calculated by XVMC for the patient CT and the hybrid phantom. One major contributing factor is the treatment method, deep inspiration breath hold (DIBH), used for this patient. This leads to significant differences in the organ position relative to the treatment isocenter. The transverse distances from the treatment isocenter to the inferior border of the liver, left lung, and right lung are 19.5cm, 29.5cm, and 30.0cm, respectively for the patient CT, compared with 24.3cm, 36.6cm, and 39.1cm, respectively, for the hybrid phantom. When corrected for the distance, the mean doses calculated using the hybrid phantom are within 28% of those calculated using the patient CT. Conclusion: This study showed that mean dose to the organs located in the missing CT coverage can be reconstructed by using whole body computational human phantoms within reasonable dosimetric uncertainty, however appropriate corrections may be necessary if the patient is treated with a technique that will significantly deform the size or location of the organs relative to the hybrid phantom.

  14. Stability of phantom wormholes

    SciTech Connect

    Lobo, Francisco S.N.

    2005-06-15

    It has recently been shown that traversable wormholes may be supported by phantom energy. In this work phantom wormhole geometries are modeled by matching an interior traversable wormhole solution, governed by the equation of state p={omega}{rho} with {omega}<-1, to an exterior vacuum spacetime at a finite junction interface. The stability analysis of these phantom wormholes to linearized spherically symmetric perturbations about static equilibrium solutions is carried out. A master equation dictating the stability regions is deduced, and by separating the cases of a positive and a negative surface energy density, it is found that the respective stable equilibrium configurations may be increased by strategically varying the wormhole throat radius. The first model considered, in the absence of a thin shell, is that of an asymptotically flat phantom wormhole spacetime. The second model constructed is that of an isotropic pressure phantom wormhole, which is of particular interest, as the notion of phantom energy is that of a spatially homogeneous cosmic fluid, although it may be extended to inhomogeneous spherically symmetric spacetimes.

  15. Head phantoms for transcranial focused ultrasound.

    PubMed

    Eames, Matthew D C; Farnum, Mercy; Khaled, Mohamad; Elias, W Jeff; Hananel, Arik; Snell, John W; Kassell, Neal F; Aubry, Jean-Francois

    2015-04-01

    In the ongoing endeavor of fine-tuning, the clinical application of transcranial MR-guided focused ultrasound (tcMRgFUS), ex-vivo studies wlkiith whole human skulls are of great use in improving the underlying technology guiding the accurate and precise thermal ablation of clinically relevant targets in the human skull. Described here are the designs, methods for fabrication, and notes on utility of three different ultrasound phantoms to be used for brain focused ultrasound research. Three different models of phantoms are developed and tested to be accurate, repeatable experimental options to provide means to further this research. The three models are a cadaver, a gel-filled skull, and a head mold containing a skull and filled with gel that mimics the brain and the skin. Each was positioned in a clinical tcMRgFUS system and sonicated at 1100 W (acoustic) for 12 s at different locations. Maximum temperature rise as measured by MR thermometry was recorded and compared against clinical data for a similar neurosurgical target. Results are presented as heating efficiency in units (°C/kW/s) for direct comparison to available clinical data. The procedure for casting thermal phantom material is presented. The utility of each phantom model is discussed in the context of various tcMRgFUS research areas. The cadaveric phantom model, gel-filled skull model, and full head phantom model had heating efficiencies of 5.3, 4.0, and 3.9 °C/(kW/s), respectively, compared to a sample clinical heating efficiency of 2.6 °C/(kW/s). In the seven research categories considered, the cadaveric phantom model was the most versatile, though less practical compared to the ex-vivo skull-based phantoms. Casting thermal phantom material was shown to be an effective way to prepare tissue-mimicking material for the phantoms presented. The phantom models presented are all useful in tcMRgFUS research, though some are better suited to a limited subset of applications depending on the researchers

  16. A comparative study of bifidobacteria in human babies and adults

    PubMed Central

    KHONSARI, Shadi; SUGANTHY, Mayuran; BURCZYNSKA, Beata; DANG, Vu; CHOUDHURY, Manika; PACHENARI, Azra

    2015-01-01

    The composition and diversity of the gut microbiota are known to be different between babies and adults. The aim of this project was to compare the level of bifidobacteria between babies and adults and to investigate the influence of lifestyle factors on the level of this bacterium in the gut. During this study, the levels of bifidobacteria in 10 human babies below 2 years of age were compared with that of 10 human adults above 40 years. The level of bifidobacteria proved to be significantly higher in babies in comparison with adults. This investigation concluded that a combination of several factors, such as age, diet, and BMI, has an important effect on the level of bifidobacteria in adults, while in babies, a combination of diet and age may influence the level of intestinal bifidobacteria. PMID:27200263

  17. Monte Carlo simulations in multi-detector CT (MDCT) for two PET/CT scanner models using MASH and FASH adult phantoms

    NASA Astrophysics Data System (ADS)

    Belinato, W.; Santos, W. S.; Paschoal, C. M. M.; Souza, D. N.

    2015-06-01

    The combination of positron emission tomography (PET) and computed tomography (CT) has been extensively used in oncology for diagnosis and staging of tumors, radiotherapy planning and follow-up of patients with cancer, as well as in cardiology and neurology. This study determines by the Monte Carlo method the internal organ dose deposition for computational phantoms created by multidetector CT (MDCT) beams of two PET/CT devices operating with different parameters. The different MDCT beam parameters were largely related to the total filtration that provides a beam energetic change inside the gantry. This parameter was determined experimentally with the Accu-Gold Radcal measurement system. The experimental values of the total filtration were included in the simulations of two MCNPX code scenarios. The absorbed organ doses obtained in MASH and FASH phantoms indicate that bowtie filter geometry and the energy of the X-ray beam have significant influence on the results, although this influence can be compensated by adjusting other variables such as the tube current-time product (mAs) and pitch during PET/CT procedures.

  18. Influence of a fat layer on the near infrared spectra of human muscle: quantitative analysis based on two-layered Monte Carlo simulations and phantom experiments

    NASA Astrophysics Data System (ADS)

    Yang, Ye; Soyemi, Olusola O.; Landry, Michelle R.; Soller, Babs R.

    2005-03-01

    Continuous wave near-IR spectroscopy (CW-NIRS) has been increasingly applied for the noninvasive, in vivo measurement of tissue and blood chemistry. It is hypothesized that there is a quantifiable relationship between fat thickness and near infrared diffuse reflectance spectra at all wavelengths, and this relationship can be used to remove the spectral influence of the overlying fat layer from the muscle spectrum. The hypothesis was investigated at a single wavelength using Monte Carlo simulations of a two-layer structure and with phantom experiments. The influence of a range of optical coefficients (absorption and reduced scattering) for fat and muscle over the known range of human physiological values was also investigated. A polynomial relationship was established between the fat thickness and the detected diffuse reflectance. It is also shown that the optical properties of the muscle and fat layers influence this relationship under certain conditions. Subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm, such as on the forearm. If NIRS measurement is to be performed on an anatomical region with a thicker fat layer, a spectral correction for fat will be needed to account for its thickness and the variation in optical coefficients for both the fat and the muscle layers.

  19. Studies on heavy charged particle interaction, water equivalence and Monte Carlo simulation in some gel dosimeters, water, human tissues and water phantoms

    NASA Astrophysics Data System (ADS)

    Kurudirek, Murat

    2015-09-01

    Some gel dosimeters, water, human tissues and water phantoms were investigated with respect to their radiological properties in the energy region 10 keV-10 MeV. The effective atomic numbers (Zeff) and electron densities (Ne) for some heavy charged particles such as protons, He ions, B ions and C ions have been calculated for the first time for Fricke, MAGIC, MAGAT, PAGAT, PRESAGE, water, adipose tissue, muscle skeletal (ICRP), muscle striated (ICRU), plastic water, WT1 and RW3 using mass stopping powers from SRIM Monte Carlo software. The ranges and straggling were also calculated for the given materials. Two different set of mass stopping powers were used to calculate Zeff for comparison. The water equivalence of the given materials was also determined based on the results obtained. The Monte Carlo simulation of the charged particle transport was also done using SRIM code. The heavy ion distribution along with its parameters were shown for the given materials for different heavy ions. Also the energy loss and damage events in water when irradiated with 100 keV heavy ions were studied in detail.

  20. A human-phantom coupling experiment and a dispersive simulation model for investigating the variation of dielectric properties of biological tissues.

    PubMed

    Gomez-Tames, Jose; Fukuhara, Yuto; He, Siyu; Saito, Kazuyuki; Ito, Koichi; Yu, Wenwei

    2015-06-01

    Variation of the dielectric properties of tissues could happen due to aging, moisture of the skin, muscle denervation, and variation of blood flow by temperature. Several studies used burst-modulated alternating stimulation to improve activation and comfort by reducing tissue impedance as a possible mechanism to generate muscle activation with less energy. The study of the effect of dielectric properties of biological tissues in nerve activation presents a fundamental problem, which is the difficulty of systematically changing the morphological factors and dielectric properties of the subjects under study. We tackle this problem by using a simulation and an experimental study. The experimental study is a novel method that combines a fat tissue-equivalent phantom, with known and adjustable dielectric properties, with the human thigh. In this way, the dispersion of the tissue under study could be modified to observe its effects systematically in muscle activation. We observed that, to generate a given amount of muscle or nerve activation under conditions of decreased impedance, the magnitude of the current needs to be increased while the magnitude of the voltage needs to be decreased.

  1. Human retrovirus in adult T-cell leukemia/lymphoma.

    PubMed

    Sugamura, K; Hinuma, Y

    1985-03-01

    In this review Kazuo Sugamura and Yorio Hinuma summarize developments in studies on the human retrovirus associated with a unique human T-cell malignancy, adult T-cell leukemia; they also discuss the possible mechanisms of retrovirus-induced leukemogenesis. Copyright © 1985. Published by Elsevier B.V.

  2. Humanities and the Adult Learner in an Information Society.

    ERIC Educational Resources Information Center

    Myers, Dale; Kamholtz, Jonathan

    Humanities courses have often been given little attention in continuing education for adults, possibly because they have been viewed as not "practical" or not "job-oriented" enough in our career-oriented, technologically advanced society. However, the humanities should be an integral part of our culture and of the lives of…

  3. Humanities and the Adult Learner in an Information Society.

    ERIC Educational Resources Information Center

    Myers, Dale; Kamholtz, Jonathan

    Humanities courses have often been given little attention in continuing education for adults, possibly because they have been viewed as not "practical" or not "job-oriented" enough in our career-oriented, technologically advanced society. However, the humanities should be an integral part of our culture and of the lives of…

  4. Phantom energy traversable wormholes

    SciTech Connect

    Lobo, Francisco S.N.

    2005-04-15

    It has been suggested that a possible candidate for the present accelerated expansion of the Universe is 'phantom energy'. The latter possesses an equation of state of the form {omega}{identical_to}p/{rho}<-1, consequently violating the null energy condition. As this is the fundamental ingredient to sustain traversable wormholes, this cosmic fluid presents us with a natural scenario for the existence of these exotic geometries. 'Note, however, that the notion of phantom energy is that of a homogeneously distributed fluid. Nevertheless, it can be extended to inhomogeneous spherically symmetric spacetimes, and it is shown that traversable wormholes may be supported by phantom energy. Because of the fact of the accelerating Universe, macroscopic wormholes could naturally be grown from the submicroscopic constructions that originally pervaded the quantum foam. One could also imagine an advanced civilization mining the cosmic fluid for phantom energy necessary to construct and sustain a traversable wormhole. In this context, we investigate the physical properties and characteristics of traversable wormholes constructed using the equation of state p={omega}{rho}, with {omega}<-1. We analyze specific wormhole geometries, considering asymptotically flat spacetimes and imposing an isotropic pressure. We also construct a thin shell around the interior wormhole solution, by imposing the phantom energy equation of state on the surface stresses. Using the 'volume integral quantifier' we verify that it is theoretically possible to construct these geometries with vanishing amounts of averaged null energy condition violating phantom energy. Specific wormhole dimensions and the traversal velocity and time are also deduced from the traversability conditions for a particular wormhole geometry. These phantom energy traversable wormholes have far-reaching physical and cosmological implications. For instance, an advanced civilization may use these geometries to induce closed timelike

  5. VOXMAT: Hybrid Computational Phantom for Dose Assessment

    SciTech Connect

    Akkurt, Hatice; Eckerman, Keith F

    2007-01-01

    The Oak Ridge National Laboratory (ORNL) computational phantoms have been the standard for assessing the radiation dose due to internal and external exposure over the past three decades. In these phantoms, the body surface and each organ are approximated by mathematical equations; hence, some of the organs are not necessarily realistic in their shape. Over the past two decades, these phantoms have been revised and updated: some of the missing internal organs have been added and the locations of the existing organs have been revised (e.g., thyroid). In the original phantom, only three elemental compositions were used to describe all body tissues. Recently, the compositions of the organs have been updated based on ICRP-89 standards. During the past decade, phantoms based on CT scans were developed for use in dose assessment. Although their shapes are realistic, some computational challenges are noted; including increased computational times and increased memory requirements. For good spatial resolution, more than several million voxels are used to represent the human body. Moreover, when CT scans are obtained, the subject is in a supine position with arms at the side. In some occupational exposure cases, it is necessary to evaluate the dose with the arms and legs in different positions. It will be very difficult and inefficient to reposition the voxels defining the arms and legs to simulate these exposure geometries. In this paper, a new approach for computational phantom development is presented. This approach utilizes the combination of a mathematical phantom and a voxelized phantom for the representation of the anatomy.

  6. Dosimetric characterization of model Cs-1 Rev2 cesium-131 brachytherapy source in water phantoms and human tissues with MCNP5 Monte Carlo simulation.

    PubMed

    Wang, Jianhua; Zhang, Hualin

    2008-04-01

    A recently developed alternative brachytherapy seed, Cs-1 Rev2 cesium-131, has begun to be used in clinical practice. The dosimetric characteristics of this source in various media, particularly in human tissues, have not been fully evaluated. The aim of this study was to calculate the dosimetric parameters for the Cs-1 Rev2 cesium-131 seed following the recommendations of the AAPM TG-43U1 report [Rivard et al., Med. Phys. 31, 633-674 (2004)] for new sources in brachytherapy applications. Dose rate constants, radial dose functions, and anisotropy functions of the source in water, Virtual Water, and relevant human soft tissues were calculated using MCNP5 Monte Carlo simulations following the TG-43U1 formalism. The results yielded dose rate constants of 1.048, 1.024, 1.041, and 1.044 cGy h(-1) U(-1) in water, Virtual Water, muscle, and prostate tissue, respectively. The conversion factor for this new source between water and Virtual Water was 1.02, between muscle and water was 1.006, and between prostate and water was 1.004. The authors' calculation of anisotropy functions in a Virtual Water phantom agreed closely with Murphy's measurements [Murphy et al., Med. Phys. 31, 1529-1538 (2004)]. Our calculations of the radial dose function in water and Virtual Water have good agreement with those in previous experimental and Monte Carlo studies. The TG-43U1 parameters for clinical applications in water, muscle, and prostate tissue are presented in this work.

  7. Breast phantom for mammary tissue characterization by near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Miranda, D. A.; Cristiano, K. L.; Gutiérrez, J. C.

    2013-11-01

    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.

  8. Characterization of a phantom setup for breast conserving cancer surgery

    NASA Astrophysics Data System (ADS)

    Chadwell, Jacob T.; Conley, Rebekah H.; Collins, Jarrod A.; Meszoely, Ingrid M.; Miga, Michael I.

    2016-03-01

    The purpose of this work is to develop an anatomically and mechanically representative breast phantom for the validation of breast conserving surgical therapies, specifically, in this case, image guided surgeries. Using three patients scheduled for lumpectomy and four healthy volunteers in mock surgical presentations, the magnitude, direction, and location of breast deformations was analyzed. A phantom setup was then designed to approximate such deformations in a mock surgical environment. Specifically, commercially available and custom-built polyvinyl alcohol (PVA) phantoms were used to mimic breast tissue during surgery. A custom designed deformation apparatus was then created to reproduce deformations seen in typical clinical setups of the pre- and intra-operative breast geometry. Quantitative analysis of the human subjects yielded a positive correlation between breast volume and amount of breast deformation. Phantom results reflected similar behavior with the custom-built PVA phantom outperforming the commercial phantom.

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

    SciTech Connect

    Traub, Richard J.

    2008-10-01

    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.

  10. Development of Chinese reference man deformable surface phantom and its application to the influence of physique on electromagnetic dosimetry

    NASA Astrophysics Data System (ADS)

    Yu, D.; Wang, M.; Liu, Q.

    2015-09-01

    A reference man is a theoretical individual that represents the average anatomical structure and physiological and metabolic features of a specific group of people and has been widely used in radiation safety research. With the help of an advantage in deformation, the present work proposed a Chinese reference man adult-male polygon-mesh surface phantom based on the Visible Chinese Human segment image dataset by surface rendering and deforming. To investigate the influence of physique on electromagnetic dosimetry in humans, a series of human phantoms with 10th, 50th and 90th body mass index and body circumference percentile physiques for Chinese adult males were further constructed by deforming the Chinese reference man surface phantom. All the surface phantoms were then voxelized to perform electromagnetic field simulation in a frequency range of 20 MHz to 3 GHz using the finite-difference time-domain method and evaluate the whole-body average and organ average specific absorption rate and the ratios of absorbed energy in skin, fat and muscle to the whole body. The results indicate thinner physique leads to higher WBSAR and the volume of subcutaneous fat, the penetration depth of the electromagnetic field in tissues and standing-wave occurrence may be the influence factors of physique on electromagnetic dosimetry.

  11. Development of Chinese reference man deformable surface phantom and its application to the influence of physique on electromagnetic dosimetry.

    PubMed

    Yu, D; Wang, M; Liu, Q

    2015-09-07

    A reference man is a theoretical individual that represents the average anatomical structure and physiological and metabolic features of a specific group of people and has been widely used in radiation safety research. With the help of an advantage in deformation, the present work proposed a Chinese reference man adult-male polygon-mesh surface phantom based on the Visible Chinese Human segment image dataset by surface rendering and deforming. To investigate the influence of physique on electromagnetic dosimetry in humans, a series of human phantoms with 10th, 50th and 90th body mass index and body circumference percentile physiques for Chinese adult males were further constructed by deforming the Chinese reference man surface phantom. All the surface phantoms were then voxelized to perform electromagnetic field simulation in a frequency range of 20 MHz to 3 GHz using the finite-difference time-domain method and evaluate the whole-body average and organ average specific absorption rate and the ratios of absorbed energy in skin, fat and muscle to the whole body. The results indicate thinner physique leads to higher WBSAR and the volume of subcutaneous fat, the penetration depth of the electromagnetic field in tissues and standing-wave occurrence may be the influence factors of physique on electromagnetic dosimetry.

  12. Differentiated human stem cells resemble fetal, not adult, β cells.

    PubMed

    Hrvatin, Sinisa; O'Donnell, Charles W; Deng, Francis; Millman, Jeffrey R; Pagliuca, Felicia Walton; DiIorio, Philip; Rezania, Alireza; Gifford, David K; Melton, Douglas A

    2014-02-25

    Human pluripotent stem cells (hPSCs) have the potential to generate any human cell type, and one widely recognized goal is to make pancreatic β cells. To this end, comparisons between differentiated cell types produced in vitro and their in vivo counterparts are essential to validate hPSC-derived cells. Genome-wide transcriptional analysis of sorted insulin-expressing (INS(+)) cells derived from three independent hPSC lines, human fetal pancreata, and adult human islets points to two major conclusions: (i) Different hPSC lines produce highly similar INS(+) cells and (ii) hPSC-derived INS(+) (hPSC-INS(+)) cells more closely resemble human fetal β cells than adult β cells. This study provides a direct comparison of transcriptional programs between pure hPSC-INS(+) cells and true β cells and provides a catalog of genes whose manipulation may convert hPSC-INS(+) cells into functional β cells.

  13. An anthropomorphic phantom for quantitative evaluation of breast MRI.

    PubMed

    Freed, Melanie; de Zwart, Jacco A; Loud, Jennifer T; El Khouli, Riham H; Myers, Kyle J; Greene, Mark H; Duyn, Jeff H; Badano, Aldo

    2011-02-01

    In this study, the authors aim to develop a physical, tissue-mimicking phantom for quantitative evaluation of breast MRI protocols. The objective of this phantom is to address the need for improved standardization in breast MRI and provide a platform for evaluating the influence of image protocol parameters on lesion detection and discrimination. Quantitative comparisons between patient and phantom image properties are presented. The phantom is constructed using a mixture of lard and egg whites, resulting in a random structure with separate adipose- and glandular-mimicking components. T1 and T2 relaxation times of the lard and egg components of the phantom were estimated at 1.5 T from inversion recovery and spin-echo scans, respectively, using maximum-likelihood methods. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of phantom and patient images. A static, enhancing lesion was introduced by creating a hollow mold with stereolithography and filling it with a gadolinium-doped water solution. Measured phantom relaxation values fall within 2 standard errors of human values from the literature and are reasonably stable over 9 months of testing. Comparison of the covariance matrices of phantom and patient data demonstrates that the phantom and patient data have similar image structure. Their covariance matrices are the same to within error bars in the anterior-posterior direction and to within about two error bars in the right-left direction. The signal from the phantom's adipose-mimicking material can be suppressed using active fat-suppression protocols. A static, enhancing lesion can also be included with the ability to change morphology and contrast agent concentration. The authors have constructed a phantom and demonstrated its ability to mimic human breast images in terms of key physical properties that are relevant to breast MRI. This phantom provides a platform for the optimization and standardization of

  14. 21 CFR 892.1380 - Nuclear flood source phantom.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear flood source phantom. 892.1380 Section 892.1380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1380 Nuclear flood source phantom. (a...

  15. 21 CFR 892.1380 - Nuclear flood source phantom.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear flood source phantom. 892.1380 Section 892.1380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1380 Nuclear flood source phantom. (a...

  16. 21 CFR 892.1380 - Nuclear flood source phantom.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nuclear flood source phantom. 892.1380 Section 892.1380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1380 Nuclear flood source phantom. (a...

  17. 21 CFR 892.1370 - Nuclear anthropomorphic phantom.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear anthropomorphic phantom. 892.1370 Section 892.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1370 Nuclear anthropomorphic phantom...

  18. 21 CFR 892.1380 - Nuclear flood source phantom.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nuclear flood source phantom. 892.1380 Section 892.1380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1380 Nuclear flood source phantom. (a...

  19. 21 CFR 892.1370 - Nuclear anthropomorphic phantom.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nuclear anthropomorphic phantom. 892.1370 Section 892.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1370 Nuclear anthropomorphic phantom...

  20. 21 CFR 892.1370 - Nuclear anthropomorphic phantom.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear anthropomorphic phantom. 892.1370 Section 892.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1370 Nuclear anthropomorphic phantom...

  1. 21 CFR 892.1370 - Nuclear anthropomorphic phantom.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nuclear anthropomorphic phantom. 892.1370 Section 892.1370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1370 Nuclear anthropomorphic phantom...

  2. Fabrication of subcutaneous veins phantom for vessel visualization system

    NASA Astrophysics Data System (ADS)

    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.

  3. Late Pleistocene adult mortality patterns and modern human establishment.

    PubMed

    Trinkaus, Erik

    2011-01-25

    The establishment of modern humans in the Late Pleistocene, subsequent to their emergence in eastern Africa, is likely to have involved substantial population increases, during their initial dispersal across southern Asia and their subsequent expansions throughout Africa and into more northern Eurasia. An assessment of younger (20-40 y) versus older (>40 y) adult mortality distributions for late archaic humans (principally Neandertals) and two samples of early modern humans (Middle Paleolithic and earlier Upper Paleolithic) provides little difference across the samples. All three Late Pleistocene samples have a dearth of older individuals compared with Holocene ethnographic/historical samples. They also lack older adults compared with Holocene paleodemographic profiles that have been critiqued for having too few older individuals for subsistence, social, and demographic viability. Although biased, probably through a combination of preservation, age assessment, and especially Pleistocene mobility requirements, these adult mortality distributions suggest low life expectancy and demographic instability across these Late Pleistocene human groups. They indicate only subtle and paleontologically invisible changes in human paleodemographics with the establishment of modern humans; they provide no support for a life history advantage among early modern humans.

  4. Late Pleistocene adult mortality patterns and modern human establishment

    PubMed Central

    Trinkaus, Erik

    2011-01-01

    The establishment of modern humans in the Late Pleistocene, subsequent to their emergence in eastern Africa, is likely to have involved substantial population increases, during their initial dispersal across southern Asia and their subsequent expansions throughout Africa and into more northern Eurasia. An assessment of younger (20–40 y) versus older (>40 y) adult mortality distributions for late archaic humans (principally Neandertals) and two samples of early modern humans (Middle Paleolithic and earlier Upper Paleolithic) provides little difference across the samples. All three Late Pleistocene samples have a dearth of older individuals compared with Holocene ethnographic/historical samples. They also lack older adults compared with Holocene paleodemographic profiles that have been critiqued for having too few older individuals for subsistence, social, and demographic viability. Although biased, probably through a combination of preservation, age assessment, and especially Pleistocene mobility requirements, these adult mortality distributions suggest low life expectancy and demographic instability across these Late Pleistocene human groups. They indicate only subtle and paleontologically invisible changes in human paleodemographics with the establishment of modern humans; they provide no support for a life history advantage among early modern humans. PMID:21220336

  5. Jamitons: Phantom Traffic Jams

    ERIC Educational Resources Information Center

    Kowszun, Jorj

    2013-01-01

    Traffic on motorways can slow down for no apparent reason. Sudden changes in speed by one or two drivers can create a chain reaction that causes a traffic jam for the vehicles that are following. This kind of phantom traffic jam is called a "jamiton" and the article discusses some of the ways in which traffic engineers produce…

  6. Jamitons: Phantom Traffic Jams

    ERIC Educational Resources Information Center

    Kowszun, Jorj

    2013-01-01

    Traffic on motorways can slow down for no apparent reason. Sudden changes in speed by one or two drivers can create a chain reaction that causes a traffic jam for the vehicles that are following. This kind of phantom traffic jam is called a "jamiton" and the article discusses some of the ways in which traffic engineers produce…

  7. The Phantom brane revisited

    NASA Astrophysics Data System (ADS)

    Sahni, Varun

    2016-07-01

    The Phantom brane is based on the normal branch of the DGP braneworld. It possesses a phantom-like equation of state at late times, but no big-rip future singularity. In this braneworld, the cosmological constant is dynamically screened at late times. Consequently it provides a good fit to SDSS DR11 measurements of H(z) at high redshifts. We obtain a closed system of equations for scalar perturbations on the brane. Perturbations of radiation, matter and the Weyl fluid are self-consistently evolved until the present epoch. We find that the late time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials φ, Ψ evolve differently on the brane than in ΛCDM, for which φ = Ψ. On the Brane, by contrast, the ratio φ/Ψ exceeds unity during the late matter dominated epoch (z ≤ 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large scale structure. The phantom brane also displays a pole in its equation of state, which provides a key test of this dark energy model.

  8. Magnetic Particle Imaging (MPI): Experimental Quantification of Vascular Stenosis Using Stationary Stenosis Phantoms.

    PubMed

    Vaalma, Sarah; Rahmer, Jürgen; Panagiotopoulos, Nikolaos; Duschka, Robert L; Borgert, Jörn; Barkhausen, Jörg; Vogt, Florian M; Haegele, Julian

    2017-01-01

    Magnetic Particle Imaging (MPI) is able to provide high temporal and good spatial resolution, high signal-to-noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs). Because of that, MPI is proposed to be a promising future method for cardiovascular imaging. Here, an interesting application may be the quantification of vascular pathologies like stenosis by utilizing the proportionality of the SPIO concentration and the MPI signal strength. In this study, the feasibility of MPI based stenosis quantification is evaluated based on this application scenario. Nine different stenosis phantoms with a normal diameter of 10 mm each and different stenoses of 1-9 mm and ten reference phantoms with a straight diameter of 1-10 mm were filled with a 1% Resovist dilution and measured in a preclinical MPI-demonstrator. The MPI signal intensities of the reference phantoms were compared to each other and the change of signal intensity within each stenosis phantom was used to calculate the degree of stenosis. These values were then compared to the known diameters of each phantom. As a second measurement, the 5 mm stenosis phantom was used for a serial dilution measurement down to a Resovist dilution of 1:3200 (0.031%), which is lower than a first pass blood concentration of a Resovist bolus in the peripheral arteries of an average adult human of at least about 1:1000. The correlation of the stenosis values based on MPI signal intensity measurements and based on the known diameters showed a very good agreement, proving the high precision of quantitative MPI in this regard.

  9. Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation

    PubMed Central

    Sun, Wenjuan; JIA, Xianghong; XIE, Tianwu; XU, Feng; LIU, Qian

    2013-01-01

    With the rapid development of China's space industry, the importance of radiation protection is increasingly prominent. To provide relevant dose data, we first developed the Visible Chinese Human adult Female (VCH-F) phantom, and performed further modifications to generate the VCH-F Astronaut (VCH-FA) phantom, incorporating statistical body characteristics data from the first batch of Chinese female astronauts as well as reference organ mass data from the International Commission on Radiological Protection (ICRP; both within 1% relative error). Based on cryosection images, the original phantom was constructed via Non-Uniform Rational B-Spline (NURBS) boundary surfaces to strengthen the deformability for fitting the body parameters of Chinese female astronauts. The VCH-FA phantom was voxelized at a resolution of 2 × 2 × 4 mm3for radioactive particle transport simulations from isotropic protons with energies of 5000–10 000 MeV in Monte Carlo N-Particle eXtended (MCNPX) code. To investigate discrepancies caused by anatomical variations and other factors, the obtained doses were compared with corresponding values from other phantoms and sex-averaged doses. Dose differences were observed among phantom calculation results, especially for effective dose with low-energy protons. Local skin thickness shifts the breast dose curve toward high energy, but has little impact on inner organs. Under a shielding layer, organ dose reduction is greater for skin than for other organs. The calculated skin dose per day closely approximates measurement data obtained in low-Earth orbit (LEO). PMID:23135158

  10. Magnetic Particle Imaging (MPI): Experimental Quantification of Vascular Stenosis Using Stationary Stenosis Phantoms

    PubMed Central

    Vaalma, Sarah; Rahmer, Jürgen; Panagiotopoulos, Nikolaos; Duschka, Robert L.; Borgert, Jörn; Barkhausen, Jörg; Vogt, Florian M.

    2017-01-01

    Magnetic Particle Imaging (MPI) is able to provide high temporal and good spatial resolution, high signal-to-noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs). Because of that, MPI is proposed to be a promising future method for cardiovascular imaging. Here, an interesting application may be the quantification of vascular pathologies like stenosis by utilizing the proportionality of the SPIO concentration and the MPI signal strength. In this study, the feasibility of MPI based stenosis quantification is evaluated based on this application scenario. Nine different stenosis phantoms with a normal diameter of 10 mm each and different stenoses of 1–9 mm and ten reference phantoms with a straight diameter of 1–10 mm were filled with a 1% Resovist dilution and measured in a preclinical MPI-demonstrator. The MPI signal intensities of the reference phantoms were compared to each other and the change of signal intensity within each stenosis phantom was used to calculate the degree of stenosis. These values were then compared to the known diameters of each phantom. As a second measurement, the 5 mm stenosis phantom was used for a serial dilution measurement down to a Resovist dilution of 1:3200 (0.031%), which is lower than a first pass blood concentration of a Resovist bolus in the peripheral arteries of an average adult human of at least about 1:1000. The correlation of the stenosis values based on MPI signal intensity measurements and based on the known diameters showed a very good agreement, proving the high precision of quantitative MPI in this regard. PMID:28056102

  11. Linking adult hippocampal neurogenesis with human physiology and disease.

    PubMed

    Bowers, Megan; Jessberger, Sebastian

    2016-07-01

    We here review the existing evidence linking adult hippocampal neurogenesis and human brain function in physiology and disease. Furthermore, we aim to point out where evidence is missing, highlight current promising avenues of investigation, and suggest future tools and approaches to foster the link between life-long neurogenesis and human brain function. Developmental Dynamics 245:702-709, 2016. © 2016 Wiley Periodicals, Inc.

  12. Egg White Phantoms for HIFU

    SciTech Connect

    Divkovic, Gabriela; Jenne, Juergen W.

    2005-03-28

    We used fresh egg white and polyacrylamide to create a transparent tissue mimicking phantom. Heating of phantoms by HIFU leads to egg white protein denaturation and creation of visible white lesions. We measured the acoustical and thermal properties and investigated the possibility to use such phantoms to study the lesion formation during the HIFU therapy.

  13. Maps of the adult human hypothalamus

    PubMed Central

    Lemaire, Jean-Jacques; Nezzar, Hachemi; Sakka, Laurent; Boirie, Yves; Fontaine, Denys; Coste, Aurélien; Coll, Guillaume; Sontheimer, Anna; Sarret, Catherine; Gabrillargues, Jean; De Salles, Antonio

    2013-01-01

    The human hypothalamus is a small deeply located region placed at the crossroad of neurovegetative, neuroendocrine, limbic, and optic systems. Although deep brain stimulation techniques have proven that it could be feasible to modulate these systems, targeting the hypothalamus and in particular specific nuclei and white bundles, is still challenging. Our goal was to make a synthesis of relevant topographical data of the human hypothalamus, under the form of magnetic resonance imaging maps useful for mastering its elaborated structure as well as its neighborhood. As from 1.5 Tesla, Inversion-Recovery sequence allows locating the hypothalamus and most of its components. Spotting hypothalamic compartments is possible according to specific landmarks: the anterior commissure, the mammillary bodies, the preoptic recess, the infundibular recess, the crest between the preoptic and the infundibular recesses, the optical tract, the fornix, and the mammillo-thalamic bundle. The identification of hypothalamus and most of its components could be useful to allow the quantification of local pathological processes and to target specific circuitry to alleviate severe symptoms, using physical or biological agents. PMID:23682342

  14. Human Service Planning as a Collective Adult Learning Experience.

    ERIC Educational Resources Information Center

    Wright, Joan

    Based on a study by the Department of Community Service Education, Cornell University, to evaluate human service planning (HSP) nationwide, this paper discusses the premises that HSP may be defined as community learning and that the community (according to the Robert Boyd and Jerold Apps model for adult education) is both a beneficiary of and…

  15. Expansion of Multipotent Stem Cells from the Adult Human Brain

    PubMed Central

    Murrell, Wayne; Palmero, Emily; Bianco, John; Stangeland, Biljana; Joel, Mrinal; Paulson, Linda; Thiede, Bernd; Grieg, Zanina; Ramsnes, Ingunn; Skjellegrind, Håvard K.; Nygård, Ståle; Brandal, Petter; Sandberg, Cecilie; Vik-Mo, Einar; Palmero, Sheryl; Langmoen, Iver A.

    2013-01-01

    The discovery of stem cells in the adult human brain has revealed new possible scenarios for treatment of the sick or injured brain. Both clinical use of and preclinical research on human adult neural stem cells have, however, been seriously hampered by the fact that it has been impossible to passage these cells more than a very few times and with little expansion of cell numbers. Having explored a number of alternative culturing conditions we here present an efficient method for the establishment and propagation of human brain stem cells from whatever brain tissue samples we have tried. We describe virtually unlimited expansion of an authentic stem cell phenotype. Pluripotency proteins Sox2 and Oct4 are expressed without artificial induction. For the first time multipotency of adult human brain-derived stem cells is demonstrated beyond tissue boundaries. We characterize these cells in detail in vitro including microarray and proteomic approaches. Whilst clarification of these cells’ behavior is ongoing, results so far portend well for the future repair of tissues by transplantation of an adult patient’s own-derived stem cells. PMID:23967194

  16. Adult Education, Basic Human Needs, and Integrated Development Planning

    ERIC Educational Resources Information Center

    Green, Reginald Herbold

    1976-01-01

    This paper argues for an integrated approach to adult education which would require an examination of basic human needs and national development planning each in its own terms. The paper's argument is centered on liberation and participation as ends, not means: Education, development, and planning must be seen and acted on as an integrated whole.…

  17. Study on fibrous materials for brain phantoms.

    PubMed

    Guise, Catarina; Fangueiro, Raul; Nóbrega, João Miguel; Schneider, Walter

    2014-01-01

    Generally, current clinical imaging methods do not provide highly detailed information about location of axonal injury, severity of injury or expected recovery of patients with traumatic brain injury (TBI). High-Definition Fiber Tractography (HDFT) is a novel imaging modality that allows visualizing and quantifying, directly, the degree of axons damage, predicting functional deficits due to traumatic axonal injury and loss of cortical projections. This imaging modality is based on diffusion technology. Being a novel modality, validation and quality control are essential. Thus this study aims at the development of a brain phantom to mimic the human brain in order to fill some gaps that currently exist in this area. This paper is focused on this novel imaging approach, the role of brain phantoms on its validation and the quality control, as well as, on the materials used in their construction. Furthermore, some important characteristics of fibrous materials for brain phantom are also discussed.

  18. New eye phantom for ophthalmic surgery

    NASA Astrophysics Data System (ADS)

    Fogli, Gessica; Orsi, Gianni; De Maria, Carmelo; Montemurro, Francesca; Palla, Michele; Rizzo, Stanislao; Vozzi, Giovanni

    2014-06-01

    In this work, we designed and realized a new phantom able to mimic the principal mechanical, rheological, and physical cues of the human eye and that can be used as a common benchmark to validate new surgical procedures, innovative vitrectomes, and as a training system for surgeons. This phantom, in particular its synthetic humor vitreous, had the aim of reproducing diffusion properties of the natural eye and can be used as a system to evaluate the pharmacokinetics of drugs and optimization of their dose, limiting animal experiments. The eye phantom was built layer-by-layer starting from the sclera up to the retina, using low cost and easy to process polymers. The validation of the phantom was carried out by mechanical characterization of each layer, by diffusion test with commercial drugs into a purposely developed apparatus, and finally by a team of ophthalmic surgeons. Experiments demonstrated that polycaprolactone, polydimethylsiloxane, and gelatin, properly prepared, are the best materials to mimic the mechanical properties of sclera, choroid, and retina, respectively. A polyvinyl alcohol-gelatin polymeric system is the best for mimicking the viscosity of the human humor vitreous, even if the bevacizumab half-life is lower than in the human eye.

  19. A Rat Body Phantom for Radiation Analysis

    NASA Technical Reports Server (NTRS)

    Qualls, Garry D.; Clowdsley, Martha S.; Slaba, Tony C.; Walker, Steven A.

    2010-01-01

    To reduce the uncertainties associated with estimating the biological effects of ionizing radiation in tissue, researchers rely on laboratory experiments in which mono-energetic, single specie beams are applied to cell cultures, insects, and small animals. To estimate the radiation effects on astronauts in deep space or low Earth orbit, who are exposed to mixed field broad spectrum radiation, these experimental results are extrapolated and combined with other data to produce radiation quality factors, radiation weighting factors, and other risk related quantities for humans. One way to reduce the uncertainty associated with such extrapolations is to utilize analysis tools that are applicable to both laboratory and space environments. The use of physical and computational body phantoms to predict radiation exposure and its effects is well established and a wide range of human and non-human phantoms are in use today. In this paper, a computational rat phantom is presented, as well as a description of the process through which that phantom has been coupled to existing radiation analysis tools. Sample results are presented for two space radiation environments.

  20. New eye phantom for ophthalmic surgery.

    PubMed

    Fogli, Gessica; Orsi, Gianni; De Maria, Carmelo; Montemurro, Francesca; Palla, Michele; Rizzo, Stanislao; Vozzi, Giovanni

    2014-06-01

    In this work, we designed and realized a new phantom able to mimic the principal mechanical, rheological, and physical cues of the human eye and that can be used as a common benchmark to validate new surgical procedures, innovative vitrectomes, and as a training system for surgeons. This phantom, in particular its synthetic humor vitreous, had the aim of reproducing diffusion properties of the natural eye and can be used as a system to evaluate the pharmacokinetics of drugs and optimization of their dose, limiting animal experiments. The eye phantom was built layer-by-layer starting from the sclera up to the retina, using low cost and easy to process polymers. The validation of the phantom was carried out by mechanical characterization of each layer, by diffusion test with commercial drugs into a purposely developed apparatus, and finally by a team of ophthalmic surgeons. Experiments demonstrated that polycaprolactone, polydimethylsiloxane, and gelatin, properly prepared, are the best materials to mimic the mechanical properties of sclera, choroid, and retina, respectively. A polyvinyl alcohol-gelatin polymeric system is the best for mimicking the viscosity of the human humor vitreous, even if the bevacizumab half-life is lower than in the human eye.

  1. An anthropomorphic phantom for quantitative evaluation of breast MRI

    PubMed Central

    Freed, Melanie; de Zwart, Jacco A.; Loud, Jennifer T.; El Khouli, Riham H.; Myers, Kyle J.; Greene, Mark H.; Duyn, Jeff H.; Badano, Aldo

    2011-01-01

    Purpose: In this study, the authors aim to develop a physical, tissue-mimicking phantom for quantitative evaluation of breast MRI protocols. The objective of this phantom is to address the need for improved standardization in breast MRI and provide a platform for evaluating the influence of image protocol parameters on lesion detection and discrimination. Quantitative comparisons between patient and phantom image properties are presented. Methods: The phantom is constructed using a mixture of lard and egg whites, resulting in a random structure with separate adipose- and glandular-mimicking components. T1 and T2 relaxation times of the lard and egg components of the phantom were estimated at 1.5 T from inversion recovery and spin-echo scans, respectively, using maximum-likelihood methods. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of phantom and patient images. A static, enhancing lesion was introduced by creating a hollow mold with stereolithography and filling it with a gadolinium-doped water solution. Results: Measured phantom relaxation values fall within 2 standard errors of human values from the literature and are reasonably stable over 9 months of testing. Comparison of the covariance matrices of phantom and patient data demonstrates that the phantom and patient data have similar image structure. Their covariance matrices are the same to within error bars in the anterior-posterior direction and to within about two error bars in the right-left direction. The signal from the phantom’s adipose-mimicking material can be suppressed using active fat-suppression protocols. A static, enhancing lesion can also be included with the ability to change morphology and contrast agent concentration. Conclusions: The authors have constructed a phantom and demonstrated its ability to mimic human breast images in terms of key physical properties that are relevant to breast MRI. This phantom provides a platform for

  2. Distinct functional programming of human fetal and adult monocytes.

    PubMed

    Krow-Lucal, Elisabeth R; Kim, Charles C; Burt, Trevor D; McCune, Joseph M

    2014-03-20

    Preterm birth affects 1 out of 9 infants in the United States and is the leading cause of long-term neurologic handicap and infant mortality, accounting for 35% of all infant deaths in 2008. Although cytokines including interferon-γ (IFN-γ), interleukin-10 (IL-10), IL-6, and IL-1 are produced in response to in utero infection and are strongly associated with preterm labor, little is known about how human fetal immune cells respond to these cytokines. We demonstrate that fetal and adult CD14(+)CD16(-) classical monocytes are distinct in terms of basal transcriptional profiles and in phosphorylation of signal transducers and activators of transcription (STATs) in response to cytokines. Fetal monocytes phosphorylate canonical and noncanonical STATs and respond more strongly to IFN-γ, IL-6, and IL-4 than adult monocytes. We demonstrate a higher ratio of SOCS3 to IL-6 receptor in adult monocytes than in fetal monocytes, potentially explaining differences in STAT phosphorylation. Additionally, IFN-γ signaling results in upregulation of antigen presentation and costimulatory machinery in adult, but not fetal, monocytes. These findings represent the first evidence that primary human fetal and adult monocytes are functionally distinct, potentially explaining how these cells respond differentially to cytokines implicated in development, in utero infections, and the pathogenesis of preterm labor.

  3. Solid anthropomorphic infant whole body DXA phantom: Design, evaluation, and multisite testing

    USDA-ARS?s Scientific Manuscript database

    Dual energy X-ray absorptiometry (DXA) requires phantoms for quality control and cross-calibration. No commercially available phantoms are designed specifically for infant whole-body scanning. We fabricated a phantom closely matching a 7-kg human infant in body habitus using PVC, nylon-mix, and poly...

  4. Regular phantom black holes.

    PubMed

    Bronnikov, K A; Fabris, J C

    2006-06-30

    We study self-gravitating, static, spherically symmetric phantom scalar fields with arbitrary potentials (favored by cosmological observations) and single out 16 classes of possible regular configurations with flat, de Sitter, and anti-de Sitter asymptotics. Among them are traversable wormholes, bouncing Kantowski-Sachs (KS) cosmologies, and asymptotically flat black holes (BHs). A regular BH has a Schwarzschild-like causal structure, but the singularity is replaced by a de Sitter infinity, giving a hypothetic BH explorer a chance to survive. It also looks possible that our Universe has originated in a phantom-dominated collapse in another universe, with KS expansion and isotropization after crossing the horizon. Explicit examples of regular solutions are built and discussed. Possible generalizations include k-essence type scalar fields (with a potential) and scalar-tensor gravity.

  5. Tissue-like phantoms

    DOEpatents

    Frangioni, John V.; De Grand, Alec M.

    2007-10-30

    The invention is based, in part, on the discovery that by combining certain components one can generate a tissue-like phantom that mimics any desired tissue, is simple and inexpensive to prepare, and is stable over many weeks or months. In addition, new multi-modal imaging objects (e.g., beads) can be inserted into the phantoms to mimic tissue pathologies, such as cancer, or merely to serve as calibration standards. These objects can be imaged using one, two, or more (e.g., four) different imaging modalities (e.g., x-ray computed tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and near-infrared (NIR) fluorescence) simultaneously.

  6. The Phantom SPH code

    NASA Astrophysics Data System (ADS)

    Price, Daniel; Wurster, James; Nixon, Chris

    2016-05-01

    I will present the capabilities of the Phantom SPH code for global simulations of dust and gas in protoplanetary discs. I will present our new algorithms for simulating both small and large grains in discs, as well as our progress towards simulating evolving grain populations and coupling with radiation. Finally, I will discuss our recent applications to HL Tau and the physics of dust gap opening.

  7. Crossing the phantom divide

    SciTech Connect

    Kunz, Martin; Sapone, Domenico

    2006-12-15

    We consider fluid perturbations close to the 'phantom divide' characterized by p=-{rho} and discuss the conditions under which divergencies in the perturbations can be avoided. We find that the behavior of the perturbations depends crucially on the prescription for the pressure perturbation {delta}p. The pressure perturbation is usually defined using the dark energy rest-frame, but we show that this frame becomes unphysical at the divide. If the pressure perturbation is kept finite in any other frame, then the phantom divide can be crossed. Our findings are important for generalized fluid dark energy used in data analysis (since current cosmological data sets indicate that the dark energy is characterized by p{approx_equal}-{rho} so that p<-{rho} cannot be excluded) as well as for any models crossing the phantom divide, like some modified gravity, coupled dark energy, and braneworld models. We also illustrate the results by an explicit calculation for the 'Quintom' case with two scalar fields.

  8. Does Acute Normobaric Hypoxia Induce Anapyrexia in Adult Humans?

    PubMed

    Seo, Yongsuk; Gerhart, Hayden D; Vaughan, Jeremiah; Kim, Jung-Hyun; Glickman, Ellen L

    2017-06-01

    Seo, Yongsuk, Hayden D. Gerhart, Jeremiah Vaughan, Jung-Hyun Kim, and Ellen L. Glickman. Does acute normobaric hypoxia induce anapyrexia in adult humans? High Alt Med Biol. 18:185-190, 2017.-Exposure to hypoxia is known to induce a reduction in core body temperature as a protective mechanism, which has been shown in both animals and humans. The purpose of this study was to test if acute exposure to normobaric hypoxia (NH) induces anapyrexia in adult humans in association with decreased peripheral oxygen saturation (SpO2). Ten healthy male subjects were seated in atmospheres of normobaric normoxia 21% (NN21), NH 17% (NH17), and 13% (NH13) O2 for 60 minutes in a counterbalanced manner. Rectal temperature (Tre) was continuously monitored together with the quantification of metabolic heat production (MHP) and body heat storage (S). Baseline physiological measurements showed no differences between the three conditions. SpO2 was significantly decreased in NH17 and NH13 compared with NN21 (p ≤ 0.001). Tre decreased following 60 minutes of resting in all conditions, but, independent of the conditions, showed no association between Tre and levels of hypoxic SpO2. There was also no significant difference in either MHP or S between conditions. The present results showed no evidence of hypoxia-induced anapyrexia in adult humans during 1 hour of resting after exposure to NH either at 13% or 17% O2.

  9. Perivascular mesenchymal progenitors in human fetal and adult liver.

    PubMed

    Gerlach, Jörg C; Over, Patrick; Turner, Morris E; Thompson, Robert L; Foka, Hubert G; Chen, William C W; Péault, Bruno; Gridelli, Bruno; Schmelzer, Eva

    2012-12-10

    The presence of mesenchymal stem cells (MSCs) has been described in various organs. Pericytes possess a multilineage differentiation potential and have been suggested to be one of the developmental sources for MSCs. In human liver, pericytes have not been defined. Here, we describe the identification, purification, and characterization of pericytes in human adult and fetal liver. Flow cytometry sorting revealed that human adult and fetal liver contains 0.56%±0.81% and 0.45%±0.39% of CD146(+)CD45(-)CD56(-)CD34(-) pericytes, respectively. Of these, 41% (adult) and 30% (fetal) were alkaline phosphatase-positive (ALP(+)). In situ, pericytes were localized around periportal blood vessels and were positive for NG2 and vimentin. Purified pericytes could be cultured extensively and had low population doubling times. Immunofluorescence of cultures demonstrated that cells were positive for pericyte and mesenchymal cell markers CD146, NG2, CD90, CD140b, and vimentin, and negative for endothelial, hematopoietic, stellate, muscle, or liver epithelial cell markers von Willebrand factor, CD31, CD34, CD45, CD144, CD326, CK19, albumin, α-fetoprotein, CYP3A7, glial fibrillary acid protein, MYF5, and Pax7 by gene expression; myogenin and alpha-smooth muscle actin expression were variable. Fluorescence-activated cell sorting analysis of cultures confirmed surface expression of CD146, CD73, CD90, CD10, CD13, CD44, CD105, and ALP and absence of human leukocyte antigen-DR. In vitro differentiation assays demonstrated that cells possessed robust osteogenic and myogenic, but low adipogenic and low chondrogenic differentiation potentials. In functional in vitro assays, cells had typical mesenchymal strong migratory and invasive activity. In conclusion, human adult and fetal livers harbor pericytes that are similar to those found in other organs and are distinct from hepatic stellate cells.

  10. Improving in vivo calibration phantoms

    SciTech Connect

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

    1991-10-01

    Anthropomorphic phantoms have been the basis for quantification of radioactive material in the body using in vivo measurements. The types of phantoms used and the degree of anthropomorphic detail vary depending on the counting application, the radioactive material to be measured, phantom availability and cost. Consequently, measurement results for the same types of radioactive material from different facilities are not always comparable. At a February 1990 meeting at the National Institute of Standards and Technology (NIST) the need to develop the gold standards'' or primary reference standards for in vivo phantoms was discussed in detail. The consensus of the attendees at the meeting was that the state of the art in phantoms was adequate as a starting point and that there was no need to start phantom development from scratch. In particular, the torso phantom developed at the Lawrence Livermore National Laboratory (LLNL) and its commercial progeny, the bottle manikin absorption (BOMAB) phantom and the American National Standards Institute (ANSI) Standard N44.3 thyroid phantom, were identified as the starting points for the development of the primary reference standards. Working groups at the meeting subsequently recommended design improvements for the existing phantom designs. The implementation of these recommendations is the subject of this paper.

  11. Matroshka-R Phantom experiment

    NASA Image and Video Library

    2006-12-01

    ISS014-E-09097 (December 2006) --- European Space Agency (ESA) astronaut Thomas Reiter, Expedition 14 flight engineer, works with the European Matroshka-R Phantom experiment in the Zvezda Service Module of the International Space Station. Matroshka, the name for the traditional Russian set of nestling dolls, is an antroph-amorphous model of a human torso designed for radiation studies. The activity, supported by ground specialist tag-up, requires equipping the torso's individual horizontal slice-like layers with 356 thermo luminescent detectors (TLDs) and five nuclear radiation tracking detectors (NTDPs). The mannequin was then to be reassembled, covered with poncho and hood and installed in the Pirs Docking Compartment for studies of on-orbit radiation and long-term dose accumulation.

  12. [Generation of new nerve cells in the adult human brain].

    PubMed

    Poulsen, Frantz Rom; Meyer, Morten; Rasmussen, Jens Zimmer

    2003-03-31

    Generation of new nerve cells (neurogenesis) is normally considered to be limited to the fetal and early postnatal period. Thus, damaged nerve cells are not expected to be replaced by generation of new cells. The brain is, however, more plastic than previously assumed. This also includes neurogenesis in the adult human brain. In particular two brain regions show continuous division of neural stem and progenitor cells generating neurons and glial cells, namely the subgranular zone of the dentate gyrus and the subventricular zones of the lateral ventricles. From the latter region newly generated neuroblasts (immature nerve cells) migrate toward the olfactory bulb where they differentiate into neurons. In the dentate gyrus the newly generated neurons become functionally integrated in the granule cell layer, where they are believed to be of importance to learning and memory. It is at present not known whether neurogenesis in the adult human brain can be manipulated for specific repair after brain damage.

  13. Somatosensory cortical plasticity in adult humans revealed by magnetoencephalography.

    PubMed Central

    Mogilner, A; Grossman, J A; Ribary, U; Joliot, M; Volkmann, J; Rapaport, D; Beasley, R W; Llinás, R R

    1993-01-01

    Microelectrode recordings in adult mammals have clearly demonstrated that somatosensory cortical maps reorganize following peripheral nerve injuries and functional modifications; however, such reorganization has never been directly demonstrated in humans. Using magnetoencephalography, we have been able to demonstrate the somatotopic organization of the hand area in normal humans with high spatial precision. Somatosensory cortical plasticity was detected in two adults who were studied before and after surgical separation of webbed fingers (syndactyly). The presurgical maps displayed shrunken and nonsomatotopic hand representations. Within weeks following surgery, cortical reorganization occurring over distances of 3-9 mm was evident, correlating with the new functional status of their separated digits. In contrast, no modification of the somatosensory map was observed months following transfer of a neurovascular skin island flap for sensory reconstruction of the thumb in two subjects in whom sensory transfer failed to occur. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8386377

  14. Bacteriology of moderate (chronic) periodontitis in mature adult humans.

    PubMed Central

    Moore, W E; Holdeman, L V; Cato, E P; Smibert, R M; Burmeister, J A; Ranney, R R

    1983-01-01

    A total of 171 taxa was represented among 1,900 bacterial isolates from 60 samples of sites affected with moderate periodontitis in 22 mature adult humans. The composition of the subgingival sulcus flora was statistically significantly different from that of the adjacent supragingival flora and the subgingival flora of 14 people with healthy gingiva, but was not significantly different from that of sulci affected with severe periodontitis in 21 young human adults. The sulcus floras of moderate periodontitis and severe periodontitis shared many of their predominant bacterial species, but there were differences in the relative proportions of some of these species. Similar relationships were found for seven taxa of treponemes that were cultured from the samples. PMID:6642641

  15. Gold nanoparticle contrast in a phantom and juvenile swine: models for molecular imaging of human organs using x-ray computed tomography.

    PubMed

    Boote, Evan; Fent, Genevieve; Kattumuri, Vijaya; Casteel, Stan; Katti, Kavita; Chanda, Nripen; Kannan, Raghuraman; Katti, Kattesh; Churchill, Robert

    2010-04-01

    The purpose of this study was to demonstrate the application of gold nanoparticles (AuNP) as a contrast agent for a clinical x-ray computed tomography (CT) system using a phantom and juvenile swine. A tissue-mimicking phantom with spherical inclusions containing known concentrations of Au was scanned. Swine were injected with gum Arabic stabilized Au nanoparticles (GA-AuNP), up to 85 mg kg(-1) body weight. CT scans were performed before and after the injections. Changes in Hounsfield unit (HU) values between pre- and post- injection scans were evaluated and compared to postmortem determinations of Au uptake. Average uptake of GA-AuNP in the liver of the swine was 380 microg per gram of liver and 680 microg per gram of spleen. Concentrations of Au in tissues increased the CT numbers in liver by approximately 22 HU per mg Au concentration at 80 kVp and 27 HU per mg Au concentration at 140 kVp. These data were consistent with HU changes observed for similar concentrations in the phantom. AuNP-based contrast agents may be useful in x-ray based CT. This study provides data for determining concentrations of AuNP in comparison to other contrast materials. Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.

  16. Evaluation of absorbed and effective doses to patients from radiopharmaceuticals using the ICRP 110 reference computational phantoms and ICRP 103 formulation.

    PubMed

    Hadid, Lama; Gardumi, Anna; Desbrée, Aurélie

    2013-09-01

    In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some

  17. Lymphatic Stomata in the Adult Human Pulmonary Ligament

    PubMed Central

    Miura, Masahiro; Iobe, Hiroaki; Kudo, Tomoo; Shimazu, Yoshihito; Aoba, Takaaki; Okudela, Koji; Nagahama, Kiyotaka; Sakamaki, Kentaro; Yoshida, Maki; Nagao, Toshitaka; Nakaya, Takeo; Kurata, Atsushi; Ohtani, Osamu

    2015-01-01

    Abstract Background: Lymphatic stomata are small lymphatic openings in the serosal membrane that communicate with the serosal cavity. Although these stomata have primarily been studied in experimental mammals, little is known concerning the presence and properties of lymphatic stomata in the adult human pleura. Thus, adult human pleurae were examined for the presence or absence of lymphatic stomata. Methods and Results: A total of 26 pulmonary ligaments (13 left and 13 right) were obtained from 15 adult human autopsy cases and examined using electron and light microscopy. The microscopic studies revealed the presence of apertures fringed with D2-40-positive, CD31-positive, and cytokeratin-negative endothelial cells directly communicating with submesothelial lymphatics in all of the pulmonary ligaments. The apertures' sizes and densities varied from case to case according to the serial tissue section. The medians of these aperture sizes ranged from 2.25 to 8.75 μm in the left pulmonary ligaments and from 2.50 to 12.50 μm in the right pulmonary ligaments. The densities of the apertures ranged from 2 to 9 per mm2 in the left pulmonary ligaments and from 2 to 18 per mm2 in the right pulmonary ligaments. However, no significant differences were found regarding the aperture size (p=0.359) and density (p=0.438) between the left and the right pulmonary ligaments. Conclusions: Our study revealed that apertures exhibit structural adequacy as lymphatic stomata on the surface of the pulmonary ligament, thereby providing evidence that lymphatic stomata are present in the adult human pleura. PMID:25526320

  18. MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research: Computer models that take account of body movements promise to provide evaluation and improvement of medical imaging devices and technology.

    PubMed

    Paul Segars, W; Tsui, Benjamin M W

    2009-12-01

    Recent work in the development of computerized phantoms has focused on the creation of ideal "hybrid" models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be

  19. Doublecortin expression in the normal and epileptic adult human brain.

    PubMed

    Liu, Y W J; Curtis, M A; Gibbons, H M; Mee, E W; Bergin, P S; Teoh, H H; Connor, B; Dragunow, M; Faull, R L M

    2008-12-01

    Mesial temporal lobe epilepsy (MTLE) is a neurological disorder associated with spontaneous recurrent complex partial seizures and hippocampal sclerosis. Although increased hippocampal neurogenesis has been reported in animal models of MTLE, increased neurogenesis has not been reported in the hippocampus of adult human MTLE cases. Here we showed that cells expressing doublecortin (Dcx), a microtubule-associated protein expressed in migrating neuroblasts, were present in the hippocampus and temporal cortex of the normal and MTLE adult human brain. In particular, increased numbers of Dcx-positive cells were observed in the epileptic compared with the normal temporal cortex. Importantly, 56% of Dcx-expressing cells in the epileptic temporal cortex coexpressed both the proliferative cell marker, proliferating cell nuclear antigen and early neuronal marker, TuJ1, suggesting that they may be newly generated neurons. A subpopulation of Dcx-positive cells in the epileptic temporal cortex also coexpressed the mature neuronal marker, NeuN, suggesting that epilepsy may promote the generation of new neurons in the temporal cortex. This study has identified, for the first time, a novel population of Dcx-positive cells in the adult human temporal cortex that can be upregulated by epilepsy and thus, raises the possibility that these cells may have functional significance in the pathophysiology of epilepsy.

  20. The phantom illusion.

    PubMed

    Galmonte, Alessandra; Soranzo, Alessandro; Rudd, Michael E; Agostini, Tiziano

    2015-12-01

    It is well known that visible luminance gradients may generate contrast effects. In this work we present a new paradoxical illusion in which the luminance range of gradual transitions has been reduced to make them invisible. By adopting the phenomenological method proposed by Kanizsa, we have found that unnoticeable luminance gradients still generate contrast effects. But, most interestingly, we have found that when their width is narrowed, rather than generating contrast effects on the surrounded surfaces, they generate an assimilation effect. Both high- and low-level interpretations of this "phantom" illusion are critically evaluated.

  1. Mouse xenograft modeling of human adult acute lymphoblastic leukemia provides mechanistic insights into adult LIC biology

    PubMed Central

    Dey, Aditi; Castleton, Anna Z.; Schwab, Claire; Samuel, Edward; Sivakumaran, Janani; Beaton, Brendan; Zareian, Nahid; Zhang, Christie Yu; Rai, Lena; Enver, Tariq; Moorman, Anthony V.; Fielding, Adele K.

    2014-01-01

    The distinct nature of acute lymphoblastic leukemia (ALL) in adults, evidenced by inferior treatment outcome and different genetic landscape, mandates specific studies of disease-initiating mechanisms. In this study, we used NOD/LtSz-scid IL2Rγ nullc (NSG) mouse xenotransplantation approaches to elucidate leukemia-initiating cell (LIC) biology in primary adult precursor B (pre-B) ALL to optimize disease modeling. In contrast with xenografting studies of pediatric ALL, we found that modification of the NSG host environment using preconditioning total body irradiation (TBI) was indispensable for efficient engraftment of adult non-t(4;11) pre-B ALL, whereas t(4;11) pre-B ALL was successfully reconstituted without this adaptation. Furthermore, TBI-based xenotransplantation of non-t(4;11) pre-B ALL enabled detection of a high frequency of LICs (<1:6900) and permitted frank leukemic engraftment from a remission sample containing drug-resistant minimal residual disease. Investigation of TBI-sensitive stromal-derived factor-1/chemokine receptor type 4 signaling revealed greater functional dependence of non-t(4;11) pre-B ALL on this niche-based interaction, providing a possible basis for the differential engraftment behavior. Thus, our studies establish the optimal conditions for experimental modeling of human adult pre-B ALL and demonstrate the critical protumorogenic role of microenvironment-derived SDF-1 in regulating adult pre-B LIC activity that may present a therapeutic opportunity. PMID:24825861

  2. Multi-Modality Phantom Development

    SciTech Connect

    Huber, Jennifer S.; Peng, Qiyu; Moses, William W.

    2009-03-20

    Multi-modality imaging has an increasing role in the diagnosis and treatment of a large number of diseases, particularly if both functional and anatomical information are acquired and accurately co-registered. Hence, there is a resulting need for multi modality phantoms in order to validate image co-registration and calibrate the imaging systems. We present our PET-ultrasound phantom development, including PET and ultrasound images of a simple prostate phantom. We use agar and gelatin mixed with a radioactive solution. We also present our development of custom multi-modality phantoms that are compatible with PET, transrectal ultrasound (TRUS), MRI and CT imaging. We describe both our selection of tissue mimicking materials and phantom construction procedures. These custom PET-TRUS-CT-MRI prostate phantoms use agargelatin radioactive mixtures with additional contrast agents and preservatives. We show multi-modality images of these custom prostate phantoms, as well as discuss phantom construction alternatives. Although we are currently focused on prostate imaging, this phantom development is applicable to many multi-modality imaging applications.

  3. Comprehensive phantom for interventional fluorescence molecular imaging

    NASA Astrophysics Data System (ADS)

    Anastasopoulou, Maria; Koch, Maximilian; Gorpas, Dimitris; Karlas, Angelos; Klemm, Uwe; Garcia-Allende, Pilar Beatriz; Ntziachristos, Vasilis

    2016-09-01

    Fluorescence imaging has been considered for over a half-century as a modality that could assist surgical guidance and visualization. The administration of fluorescent molecules with sensitivity to disease biomarkers and their imaging using a fluorescence camera can outline pathophysiological parameters of tissue invisible to the human eye during operation. The advent of fluorescent agents that target specific cellular responses and molecular pathways of disease has facilitated the intraoperative identification of cancer with improved sensitivity and specificity over nonspecific fluorescent dyes that only outline the vascular system and enhanced permeability effects. With these new abilities come unique requirements for developing phantoms to calibrate imaging systems and algorithms. We briefly review herein progress with fluorescence phantoms employed to validate fluorescence imaging systems and results. We identify current limitations and discuss the level of phantom complexity that may be required for developing a universal strategy for fluorescence imaging calibration. Finally, we present a phantom design that could be used as a tool for interlaboratory system performance evaluation.

  4. Comparison of Monoenergetic Photon Organ Dose Rate Coefficients for the Female Stylized and Voxel Phantoms Submerged in Air

    DOE PAGES

    Hiller, Mauritius; Dewji, Shaheen Azim

    2017-02-16

    Dose rate coefficients computed using the International Commission on Radiological Protection (ICRP) reference adult female voxel phantom were compared with values computed using the Oak Ridge National Laboratory (ORNL) adult female stylized phantom in an air submersion exposure geometry. This is a continuation of previous work comparing monoenergetic organ dose rate coefficients for the male adult phantoms. With both the male and female data computed, effective dose rate as defined by ICRP Publication 103 was compared for both phantoms. Organ dose rate coefficients for the female phantom and ratios of organ dose rates for the voxel and stylized phantoms aremore » provided in the energy range from 30 to 5 MeV. Analysis of the contribution of the organs to effective dose is also provided. Lastly, comparison of effective dose rates between the voxel and stylized phantoms was within 8% at 100 keV and is <5% between 200 and 5000 keV.« less

  5. Design and fabrication of a solid simplified head phantom

    NASA Astrophysics Data System (ADS)

    Tanikawa, Yukari; Imai, Daigo; Mizuno, Sho; Maki, Hiroshi; Shinozaki, Osamu; Yamada, Yukio

    1997-08-01

    Optical tomography aims to image the distribution of optical properties in human bodies by measuring transmitted light at skin surfaces. Pervious calculations and experiments have been mainly performed on phantoms with simple geometries such as slabs and cylinders, but for optical tomography it is inevitable to fully understand light propagation through and perform experiments using phantoms with complicated structures in three dimensions. Therefore, we need stable and realistic solid phantoms for experimental studies toward the goal of optical tomography. In this study, we have fabricated two types of solid phantoms which optically and anatomically simulate human heads. One has a shape and structures of a part of human head above eye plane, and the other has a more simplified shape of hemisphere. These phantoms consisted of five layers which corresponded to five tissue types in human head; i.e., skin, skull, clear CSF layer, gray matter and white matter. Size and optical properties were given according to those of human neonatal head. After taking original shapes from MRI images, prototypes of five layers were fabricated by a rapid prototyping based photolithography. Epoxy resin with titanium oxide particles as scatterers and green dye as absorber was cast into the molds of the prototypes to make optical phantoms. Absorbers simulating inhomogeneities were also embedded.

  6. An anatomically realistic temperature phantom for radiofrequency heating measurements.

    PubMed

    Graedel, Nadine N; Polimeni, Jonathan R; Guerin, Bastien; Gagoski, Borjan; Wald, Lawrence L

    2015-01-01

    An anthropomorphic phantom with realistic electrical properties allows for a more accurate reproduction of tissue current patterns during excitation. A temperature map can then probe the worst-case heating expected in the unperfused case. We describe an anatomically realistic human head phantom that allows rapid three-dimensional (3D) temperature mapping at 7T. The phantom was based on hand-labeled anatomical imaging data and consists of four compartments matching the corresponding human tissues in geometry and electrical properties. The increases in temperature resulting from radiofrequency excitation were measured with MR thermometry using a temperature-sensitive contrast agent (TmDOTMA(-)) validated by direct fiber optic temperature measurements. Acquisition of 3D temperature maps of the full phantom with a temperature accuracy better than 0.1°C was achieved with an isotropic resolution of 5 mm and acquisition times of 2-4 minutes. Our results demonstrate the feasibility of constructing anatomically realistic phantoms with complex geometries incorporating the ability to measure accurate temperature maps in the phantom. The anthropomorphic temperature phantom is expected to provide a useful tool for the evaluation of the heating effects of both conventional and parallel transmit pulses and help validate electromagnetic and temperature simulations. © 2014 Wiley Periodicals, Inc.

  7. An anatomically realistic temperature phantom for radiofrequency heating measurements

    PubMed Central

    Graedel, Nadine N.; Polimeni, Jonathan R.; Guerin, Bastien; Gagoski, Borjan; Wald, Lawrence L.

    2014-01-01

    Purpose An anthropomorphic phantom with realistic electrical properties allows for a more accurate reproduction of tissue current patterns during excitation. A temperature map can then probe the worst-case heating expected in the un-perfused case. We describe an anatomically realistic human head phantom that allows rapid 3D temperature mapping at 7 T. Methods The phantom was based on hand-labeled anatomical imaging data and consists of four compartments matching the corresponding human tissues in geometry and electrical properties. The increases in temperature resulting from radiofrequency excitation were measured with MR thermometry using a temperature sensitive contrast agent (TmDOTMA−) validated by direct fiber optic temperature measurements. Results Acquisition of 3D temperature maps of the full phantom with a temperature accuracy better than 0.1°C was achieved with an isotropic resolution of 5 mm and acquisition times of 2–4 minutes. Conclusion Our results demonstrate the feasibility of constructing anatomically realistic phantoms with complex geometries incorporating the ability to measure accurate temperature maps in the phantom. The anthropomorphic temperature phantom is expected to provide a useful tool for the evaluation of the heating effects of both conventional and parallel transmit pulses and help validate electromagnetic and temperature simulations. PMID:24549755

  8. Calicivirus infection in human immunodeficiency virus seropositive children and adults.

    PubMed

    Rodríguez-Guillén, L; Vizzi, E; Alcalá, A C; Pujol, F H; Liprandi, F; Ludert, J E

    2005-06-01

    The importance of enteric viral infections in HIV-related diarrhea is uncertain. Human caliciviruses have emerged as a leading cause of acute diarrhea worldwide. To evaluate the importance of calicivirus infections in HIV-related diarrhea. Study design 151 fecal samples collected from children and adults infected with HIV, with and without diarrhea, were examined. In addition, 89 fecal samples from non HIV-infected children and adults were also tested. Samples were analyzed by RT-PCR using primer sets specific to Norovirus genogroup I or genogroup II as well as primers designed to react with both Noroviruses and Sapovirus genus. Viruses were detected with equal frequencies in stools from HIV infected and non-infected adults (12%). However, specimens from HIV infected children were more likely than those of HIV-negative children to have caliciviruses (51% versus 24%, P<0.05). Viral infections were not significantly associated with diarrhea neither in children nor in adults, regardless of HIV status. Viruses genetically related to the common Lordsdale virus (Norovirus genogroup II) and London/92 virus (Sapovirus) clusters were detected circulating among children. These results suggest that caliciviruses may be an important opportunistic pathogen in children infected with HIV.

  9. Covert spatial attention is functionally intact in amblyopic human adults

    PubMed Central

    Roberts, Mariel; Cymerman, Rachel; Smith, R. Theodore; Kiorpes, Lynne; Carrasco, Marisa

    2016-01-01

    Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention—the selective processing of visual information in the absence of eye movements—to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults. PMID:28033433

  10. Covert spatial attention is functionally intact in amblyopic human adults.

    PubMed

    Roberts, Mariel; Cymerman, Rachel; Smith, R Theodore; Kiorpes, Lynne; Carrasco, Marisa

    2016-12-01

    Certain abnormalities in behavioral performance and neural signaling have been attributed to a deficit of visual attention in amblyopia, a neurodevelopmental disorder characterized by a diverse array of visual deficits following abnormal binocular childhood experience. Critically, most have inferred attention's role in their task without explicitly manipulating and measuring its effects against a baseline condition. Here, we directly investigate whether human amblyopic adults benefit from covert spatial attention-the selective processing of visual information in the absence of eye movements-to the same degree as neurotypical observers. We manipulated both involuntary (Experiment 1) and voluntary (Experiment 2) attention during an orientation discrimination task for which the effects of covert spatial attention have been well established in neurotypical and special populations. In both experiments, attention significantly improved accuracy and decreased reaction times to a similar extent (a) between the eyes of the amblyopic adults and (b) between the amblyopes and their age- and gender-matched controls. Moreover, deployment of voluntary attention away from the target location significantly impaired task performance (Experiment 2). The magnitudes of the involuntary and voluntary attention benefits did not correlate with amblyopic depth or severity. Both groups of observers showed canonical performance fields (better performance along the horizontal than vertical meridian and at the lower than upper vertical meridian) and similar effects of attention across locations. Despite their characteristic low-level vision impairments, covert spatial attention remains functionally intact in human amblyopic adults.

  11. The nutrition intervention improved adult human capital and economic productivity.

    PubMed

    Martorell, Reynaldo; Melgar, Paul; Maluccio, John A; Stein, Aryeh D; Rivera, Juan A

    2010-02-01

    This article reviews key findings about the long-term impact of a nutrition intervention carried out by the Institute of Nutrition of Central America and Panama from 1969 to 1977. Results from follow-up studies in 1988-89 and 2002-04 show substantial impact on adult human capital and economic productivity. The 1988-89 study showed that adult body size and work capacity increased for those provided improved nutrition through age 3 y, whereas the 2002-04 follow-up showed that schooling was increased for women and reading comprehension and intelligence increased in both men and women. Participants were 26-42 y of age at the time of the 2002-04 follow-up, facilitating the assessment of economic productivity. Wages of men increased by 46% in those provided with improved nutrition through age 2 y. Findings for cardiovascular disease risk factors were heterogeneous; however, they suggest that improved nutrition in early life is unlikely to increase cardiovascular disease risk later in life and may indeed lower risk. In conclusion, the substantial improvement in adult human capital and economic productivity resulting from the nutrition intervention provides a powerful argument for promoting improvements in nutrition in pregnant women and young children.

  12. Color-matched esophagus phantom for fluorescent imaging

    NASA Astrophysics Data System (ADS)

    Yang, Chenying; Hou, Vivian; Nelson, Leonard Y.; Seibel, Eric J.

    2013-02-01

    We developed a stable, reproducible three-dimensional optical phantom for the evaluation of a wide-field endoscopic molecular imaging system. This phantom mimicked a human esophagus structure with flexibility to demonstrate body movements. At the same time, realistic visual appearance and diffuse spectral reflectance properties of the tissue were simulated by a color matching methodology. A photostable dye-in-polymer technology was applied to represent biomarker probed "hot-spot" locations. Furthermore, fluorescent target quantification of the phantom was demonstrated using a 1.2mm ultrathin scanning fiber endoscope with concurrent fluorescence-reflectance imaging.

  13. Human-Animal Interaction and Older Adults: An Overview.

    PubMed

    Gee, Nancy R; Mueller, Megan K; Curl, Angela L

    2017-01-01

    Both pet ownership and animal-assisted therapy are becoming increasingly popular in the United States, and the science of human-animal interaction (HAI) seeks to explore how these relationships with animals can impact health and well-being. In particular, one burgeoning area of research is the role of HAI in healthy aging, given the potential for HAI as an important feature of health and well-being in older adults. The purpose of this review is to summarize and evaluate existing research in this innovative area of scholarship, identifying the potential benefits and risks of both pet ownership and animals in therapeutic settings for older adults. We will also identify recommendations for future research and applications in this developing area of scholarship.

  14. Phantom vision: a graphic description.

    PubMed

    Maloof, Anthony J

    2004-01-01

    An 80-year-old man, who is an experienced artist, underwent orbital exenteration for invasive squamous cell carcinoma. After exenteration, the patient noted a persistent, colored visual phenomenon. The phantom vision continued unchanged to 9 months after surgery (the time of writing), when the patient presented a graphic and written description of phantom vision.

  15. Multimodal Phantom of Liver Tissue

    PubMed Central

    Chmarra, Magdalena K.; Hansen, Rune; Mårvik, Ronald; Langø, Thomas

    2013-01-01

    Medical imaging plays an important role in patients' care and is continuously being used in managing health and disease. To obtain the maximum benefit from this rapidly developing technology, further research is needed. Ideally, this research should be done in a patient-safe and environment-friendly manner; for example, on phantoms. The goal of this work was to develop a protocol and manufacture a multimodal liver phantom that is suitable for ultrasound, computed tomography, and magnetic resonance imaging modalities. The proposed phantom consists of three types of mimicked soft tissues: liver parenchyma, tumors, and portal veins, that are made of six ingredients: candle gel, sephadex®, agarose, glycerol, distilled water, and silicone string. The entire procedure is advantageous, since preparation of the phantom is simple, rather cost-effective, and reasonably quick – it takes around 2 days. Besides, most of the phantom's parts can be reused to manufacture a new phantom. Comparison of ultrasound images of real patient's liver and the developed phantom shows that the phantom's liver tissue and its structures are well simulated. PMID:23691165

  16. Ultrasonic Calibration Wire Test Phantom

    SciTech Connect

    Lehman, S K; Fisher, K A; Werve, M; Chambers, D H

    2004-09-24

    We designed and built a phantom consisting of vertical wires maintained under tension to be used as an ultrasonic test, calibration, and reconstruction object for the Lawrence Livermore National Laboratory annular array scanner. We provide a description of the phantom, present example data sets, preliminary reconstructions, example metadata, and MATLAB codes to read the data.

  17. Bioassay Phantoms Using Medical Images and Computer Aided Manufacturing

    SciTech Connect

    Dr. X. Geroge Xu

    2011-01-28

    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.

  18. CCM2 expression during prenatal development and adult human neocortex.

    PubMed

    Tanriover, Gamze; Sozen, Berna; Gunel, Murat; Demir, Necdet

    2011-08-01

    Cerebral cavernous malformation (CCM) is one of the most common types of vascular malformations of the central nervous system, affecting nearly one in 200 people. CCM lesions are characterized by grossly dilated vascular channels lined by a single layer of endothelium. Genetic linkage analyses have mapped three CCM loci to CCM1, CCM2 and CCM3. All three causative genes have now been identified allowing new insights into CCM pathophysiology. We focused on the CCM2 protein that might take place in blood vessel formation; we report here the expression patterns of CCM2 in prenatal development and adult human neocortex by means of immunohistochemistry and Western blot analysis. CCM2 was obviously detected in vascular endothelium and neuroglial precursor cells during development and also observed in arterial endothelium, neurons, some of the glial cells in adult neocortex. The expression patterns suggest that it could be one of the arterial markers whether this is a cause or a consequence of an altered vascular identity. CCM2 might play a role during vasculogenesis and angiogenesis during human brain development. Furthermore, with this study, CCM2 have been described for the first time in developing human neocortex.

  19. Molecular basis of lactase levels in adult humans.

    PubMed Central

    Escher, J C; de Koning, N D; van Engen, C G; Arora, S; Büller, H A; Montgomery, R K; Grand, R J

    1992-01-01

    The molecular basis of adult human "lactase deficiency" has long been a subject of controversy. To address this issue, small intestinal biopsies from orienta, black, and white patients were analyzed. Adjacent samples were assayed for lactase and sucrase specific activities and the sucrase/lactase ratio (high ratio signifies lactase deficiency), and the results were compared to lactase steady-state mRNA levels detected in Northern blots probed with a human lactase mDNA. All oriental patients had high ratios and no detectable lactase mRNA. Four black patients had a similar pattern; two with low ratios had detectable mRNA. The group of white patients displayed a range of findings, from high ratio/no mRNA to low ratio/considerable mRNA. Elevated levels of lactase mRNA always correlated with the presence of elevated levels of lactase enzyme activity, suggesting that the difference in levels of adult human intestinal lactase activity among racial groups may be regulated at the level of gene transcription. Images PMID:1737837

  20. Conjoint recognition and phantom recollection.

    PubMed

    Brainerd, C J; Wright, R; Reyna, V F; Mojardin, A H

    2001-03-01

    A new methodology for measuring illusory conscious experience of the "presentation" of unstudied material (phantom recollection) is evaluated that extracts measurements directly from recognition responses, rather than indirectly from introspective reports. Application of this methodology in the Deese-Roediger-McDermott (DRM) paradigm (Experiments 1 and 2) and in a more conventional paradigm (Experiment 3) showed that 2 processes (phantom recollection and familiarity) contribute to false recognition of semantically related distractors. Phantom recollection was the larger contributor to false recognition of critical distractors in the DRM paradigm, but surprisingly, it was also the larger contributor to false recognition of other types of distractors. Variability in false recognition was tied to variability in phantom recollection. Experimental control of phantom recollection was achieved with manipulations that were motivated by fuzzy-trace theory's hypothesis that the phenomenon is gist-based.

  1. [Therapy of phantom limb pain].

    PubMed

    Schwarzer, Andreas; Zenz, Michael; Maier, Christoph

    2009-03-01

    About 80 % of all extremity amputations suffer from phantom limb pain following the operation. In this context, it is important to differentiate between painful phantom limb sensations, non-painful phantom limb sensations and residual limb pain. The pathophysiology of phantom limb pain is not fully understood. Current research findings ascribe a major pathophysiological role to cortical changes as well as a disturbed body perception. Peripheral and spinal mechanisms appear less relevant in the development of phantom limb pain. An essential part of the therapy is the pharmacological treatment with antidepressants, anticonvulsives and opioids. Another significant aspect of therapy is senso-motory training, important to mention here would be mirror therapy, lateralisation and motor imaging. In case of an elective amputation, an epidural or axiliar plexus catheter should be considered prior to the amputation. The perioperative treatment with ketamine is debated.

  2. NOTE: Simultaneous assessment of arsenic and selenium in human nail phantoms using a portable x-ray tube and a detector

    NASA Astrophysics Data System (ADS)

    Roy, Christopher W.; Gherase, Mihai Raul; Fleming, David E. B.

    2010-03-01

    A novel approach to the measurement of arsenic and selenium in nail phantoms is demonstrated. Two-component nail phantoms of 0.7 mm and 1.5 mm thickness were made from a polyester resin-salt mixture and dosed with equal arsenic and selenium concentrations ranging from 0 to 30 µg g-1. A backing was made to simulate the soft tissue and bone of the great toe. Characteristic x-rays for arsenic and selenium were recorded using a portable x-ray tube and a silicon PiN diode detector. The minimum instrumental detection limits for arsenic and selenium in 0.7 mm solitary nail samples were as follows: 0.510 ± 0.018 µg g-1 and 0.519 ± 0.026 µg g-1 respectively; for 1.5 mm solitary nail: 0.465 ± 0.035 µg g-1 and 0.561 ± 0.062 µg g-1 for 0.7 mm nail with backing: 1.522 ± 0.038 µg g-1 and 1.401 ± 0.049 µg g-1 for 1.5 mm nail with backing: 1.354 ± 0.054 µg g-1 and 1.367 ± 0.068 µg g-1.

  3. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    PubMed Central

    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

  4. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    NASA Astrophysics Data System (ADS)

    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.

  5. Eye contact elicits bodily self-awareness in human adults.

    PubMed

    Baltazar, Matias; Hazem, Nesrine; Vilarem, Emma; Beaucousin, Virginie; Picq, Jean-Luc; Conty, Laurence

    2014-10-01

    Eye contact is a typical human behaviour known to impact concurrent or subsequent cognitive processing. In particular, it has been suggested that eye contact induces self-awareness, though this has never been formally proven. Here, we show that the perception of a face with a direct gaze (that establishes eye contact), as compared to either a face with averted gaze or a mere fixation cross, led adult participants to rate more accurately the intensity of their physiological reactions induced by emotional pictures. Our data support the view that bodily self-awareness becomes more acute when one is subjected to another's gaze. Importantly, this effect was not related to a particular arousal state induced by eye contact perception. Rejecting the arousal hypothesis, we suggest that eye contact elicits a self-awareness process by enhancing self-focused attention in humans. We further discuss the implications of this proposal. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Ontogeny of morningness-eveningness across the adult human lifespan

    NASA Astrophysics Data System (ADS)

    Randler, Christoph

    2016-02-01

    Sleep timing of humans can be classified alongside a continuum from early to late sleepers, with some people (larks) having an early activity, early bed, and rise times and others (owls) with a more nocturnally orientated activity. Only a few studies reported that morningness-eveningness changes significantly during the adult lifespan based on community samples. Here, I applied a different methodological approach to seek for evidence for the age-related changes in morningness-eveningness preferences by using a meta-data from all available studies. The new aspect of this cross-sectional approach is that only a few studies themselves address the age-related changes of the adult lifespan development, but that many studies are available that provide exactly the data needed. The studies came from 27 countries and included 36,939 participants. Age was highly significantly correlated with scores on the Composite Scale of Morningness ( r = 0.70). This relationship seems linear, because a linear regression explained nearly the same amount of variance compared to other models such as logarithmic, quadratic, or cubic models. The standard deviation of age correlated with the standard deviation of CSM scores ( r = 0.55), suggesting when there is much variance in age in a study; in turn, there is much variance in morningness. This meta-analytical approach shows that morningness-eveningness changes across the adult lifespan and that older age is related to higher morningness.

  7. A Wearable Goggle Navigation System for Dual-Mode Optical and Ultrasound Localization of Suspicious Lesions: Validation Studies Using Tissue-Simulating Phantoms and an Ex Vivo Human Breast Tissue Model

    PubMed Central

    Wang, Dong; Gan, Qi; Ye, Jian; Yue, Jian; Wang, Benzhong; Povoski, Stephen P.; Martin, Edward W.; Hitchcock, Charles L.; Yilmaz, Alper; Tweedle, Michael F.; Shao, Pengfei; Xu, Ronald X.

    2016-01-01

    Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG)—fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting. PMID:27367051

  8. A Wearable Goggle Navigation System for Dual-Mode Optical and Ultrasound Localization of Suspicious Lesions: Validation Studies Using Tissue-Simulating Phantoms and an Ex Vivo Human Breast Tissue Model.

    PubMed

    Zhang, Zeshu; Pei, Jing; Wang, Dong; Gan, Qi; Ye, Jian; Yue, Jian; Wang, Benzhong; Povoski, Stephen P; Martin, Edward W; Hitchcock, Charles L; Yilmaz, Alper; Tweedle, Michael F; Shao, Pengfei; Xu, Ronald X

    2016-01-01

    Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG)-fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting.

  9. 4D XCAT phantom for multimodality imaging research

    PubMed Central

    Segars, W. P.; Sturgeon, G.; Mendonca, S.; Grimes, Jason; Tsui, B. M. W.

    2010-01-01

    Purpose: The authors develop the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. Methods: Highly detailed whole-body anatomies for the adult male and female were defined in the XCAT using nonuniform rational B-spline (NURBS) and subdivision surfaces based on segmentation of the Visible Male and Female anatomical datasets from the National Library of Medicine as well as patient datasets. Using the flexibility of these surfaces, the Visible Human anatomies were transformed to match body measurements and organ volumes for a 50th percentile (height and weight) male and female. The desired body measurements for the models were obtained using the PEOPLESIZE program that contains anthropometric dimensions categorized from 1st to the 99th percentile for US adults. The desired organ volumes were determined from ICRP Publication 89 [ICRP, ‘‘Basic anatomical and physiological data for use in radiological protection: reference values,” ICRP Publication 89 (International Commission on Radiological Protection, New York, NY, 2002)]. The male and female anatomies serve as standard templates upon which anatomical variations may be modeled in the XCAT through user-defined parameters. Parametrized models for the cardiac and respiratory motions were also incorporated into the XCAT based on high-resolution cardiac- and respiratory-gated multislice CT data. To demonstrate the usefulness of the phantom, the authors show example simulation studies in PET, SPECT, and CT using publicly available simulation packages. Results: As demonstrated in the pilot studies, the 4D XCAT (which includes thousands of anatomical structures) can produce realistic imaging data when combined with accurate models of the imaging process. With the flexibility of the NURBS surface primitives, any number of different anatomies, cardiac or respiratory motions or patterns, and spatial resolutions can be simulated to perform imaging research. Conclusions: With the ability to produce

  10. 4D XCAT phantom for multimodality imaging research

    SciTech Connect

    Segars, W. P.; Sturgeon, G.; Mendonca, S.; Grimes, Jason; Tsui, B. M. W.

    2010-09-15

    Purpose: The authors develop the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. Methods: Highly detailed whole-body anatomies for the adult male and female were defined in the XCAT using nonuniform rational B-spline (NURBS) and subdivision surfaces based on segmentation of the Visible Male and Female anatomical datasets from the National Library of Medicine as well as patient datasets. Using the flexibility of these surfaces, the Visible Human anatomies were transformed to match body measurements and organ volumes for a 50th percentile (height and weight) male and female. The desired body measurements for the models were obtained using the PEOPLESIZE program that contains anthropometric dimensions categorized from 1st to the 99th percentile for US adults. The desired organ volumes were determined from ICRP Publication 89 [ICRP, ''Basic anatomical and physiological data for use in radiological protection: reference values,'' ICRP Publication 89 (International Commission on Radiological Protection, New York, NY, 2002)]. The male and female anatomies serve as standard templates upon which anatomical variations may be modeled in the XCAT through user-defined parameters. Parametrized models for the cardiac and respiratory motions were also incorporated into the XCAT based on high-resolution cardiac- and respiratory-gated multislice CT data. To demonstrate the usefulness of the phantom, the authors show example simulation studies in PET, SPECT, and CT using publicly available simulation packages. Results: As demonstrated in the pilot studies, the 4D XCAT (which includes thousands of anatomical structures) can produce realistic imaging data when combined with accurate models of the imaging process. With the flexibility of the NURBS surface primitives, any number of different anatomies, cardiac or respiratory motions or patterns, and spatial resolutions can be simulated to perform imaging research. Conclusions: With the ability to produce

  11. Human Handling Promotes Compliant Behavior in Adult Laboratory Rabbits

    PubMed Central

    Swennes, Alton G; Alworth, Leanne C; Harvey, Stephen B; Jones, Carolyn A; King, Christopher S; Crowell-Davis, Sharon L

    2011-01-01

    Routine laboratory procedures can be stressful for laboratory animals. We wanted to determine whether human handling of adult rabbits could induce a degree of habituation, reducing stress and facilitating research-related manipulation. To this end, adult New Zealand white rabbits were handled either frequently or minimally. After being handled over 3 wk, these rabbits were evaluated by novel personnel and compared with minimally handled controls. Evaluators subjectively scored the rabbits for their relative compliance or resistance to being scruffed and removed from their cages, being transported to a treatment room, and their behavior at all stages of the exercise. Upon evaluation, handled rabbits scored significantly more compliant than nontreated controls. During evaluation, behaviors that the rabbits displayed when they were approached in their cages and while being handled outside their cages were recorded and compared between study groups. Handled rabbits displayed behavior consistent with a reduction in human-directed fear. This study illustrates the potential for handling to improve compliance in laboratory procedures and reduce fear-related behavior in laboratory rabbits. Such handling could be used to improve rabbit welfare through the reduction of stress and exposure to novel stimuli. PMID:21333162

  12. Human handling promotes compliant behavior in adult laboratory rabbits.

    PubMed

    Swennes, Alton G; Alworth, Leanne C; Harvey, Stephen B; Jones, Carolyn A; King, Christopher S; Crowell-Davis, Sharon L

    2011-01-01

    Routine laboratory procedures can be stressful for laboratory animals. We wanted to determine whether human handling of adult rabbits could induce a degree of habituation, reducing stress and facilitating research-related manipulation. To this end, adult New Zealand white rabbits were handled either frequently or minimally. After being handled over 3 wk, these rabbits were evaluated by novel personnel and compared with minimally handled controls. Evaluators subjectively scored the rabbits for their relative compliance or resistance to being scruffed and removed from their cages, being transported to a treatment room, and their behavior at all stages of the exercise. Upon evaluation, handled rabbits scored significantly more compliant than nontreated controls. During evaluation, behaviors that the rabbits displayed when they were approached in their cages and while being handled outside their cages were recorded and compared between study groups. Handled rabbits displayed behavior consistent with a reduction in human-directed fear. This study illustrates the potential for handling to improve compliance in laboratory procedures and reduce fear-related behavior in laboratory rabbits. Such handling could be used to improve rabbit welfare through the reduction of stress and exposure to novel stimuli.

  13. Laminin chains in developing and adult human myotendinous junctions.

    PubMed

    Pedrosa-Domellöf, F; Tiger, C F; Virtanen, I; Thornell, L E; Gullberg, D

    2000-02-01

    In addition to being the specialized site for transmission of force from the muscle to the tendon, the myotendinous junction (MTJ) also plays an important role in muscle splitting during morphogenesis. An early event in the formation of the MTJ is a regional deposition of basement membranes. We used immunocytochemistry to investigate the distribution of laminin chains during the development of MTJs in human limb muscle at 8-22 weeks of gestation (wg) and in adult MTJs. We used polyclonal antibodies and a new monoclonal antibody (MAb) against the human laminin alpha1 G4/G5 domains. At 8-10 wg, laminin alpha1 and laminin alpha5 chains were specifically localized to the MTJ. Laminin alpha1 chain remained restricted to the MTJ at 22 wg as the laminin beta2 chain had appeared, whereas the laminin alpha5 chain became deposited along the entire length of the myotubes from 12 wg. In the adult MTJ, only vestigial amounts of laminin alpha1 and laminin alpha5 chains could be detected. On the basis of co-distribution data, we speculate that laminin alpha1 chain in the forming MTJ undergoes an isoform switch from laminin 1 to laminin 3. Our data indicate a potentially important role for laminin alpha1 chain in skeletal muscle formation. (J Histochem Cytochem 48:201-209, 2000)

  14. Comprehensive comparison of neonate and adult human platelet transcriptomes

    PubMed Central

    Caparrós-Pérez, Eva; López-Andreo, Mª José; Llanos, Mª Carmen; Rivera, José; Palma-Barqueros, Verónica; Blanco, Jose E.; Vicente, Vicente; Martínez, Constantino; Ferrer-Marín, Francisca

    2017-01-01

    Understanding the underlying mechanisms of the well-substantiated platelet hyporeactivity in neonates is of interest given their implications for the clinical management of newborns, a population at higher bleeding risk than adults (especially sick and preterm infants), as well as for gaining insight into the regulatory mechanisms of platelet biology. Transcriptome analysis is useful in identifying mRNA signatures affecting platelet function. However, human fetal/neonatal platelet transcriptome analysis has never before been reported. We have used mRNA expression array for the first time to compare platelet transcriptome changes during development. Microarray analysis was performed in pure platelet RNA obtained from adult and cord blood, using the same platform in two independent laboratories. A high correlation was obtained between array results for both adult and neonate platelet samples. There was also good agreement between results in our adult samples and outcomes previously reported in three different studies. Gene enrichment analysis showed that immunity- and platelet function-related genes are highly expressed at both developmental stages. Remarkably, 201 genes were found to be differentially expressed throughout development. In particular, neonatal platelets contain higher levels of mRNA that are associated with protein synthesis and processing, while carrying significantly lower levels of genes involved in calcium transport/metabolism and cell signaling (including GNAZ). Overall, our results point to variations in platelet transcriptome as possibly underlining the hypo-functional phenotype of neonatal platelets and provide further support for the role of platelets in cellular immune response. Better characterization of the platelet transcriptome throughout development can contribute to elucidate how transcriptome changes impact different pathological conditions. PMID:28813466

  15. Computed Tomography Colonography Phantom: Construction, Validation and Literature Review

    PubMed Central

    Lambert, Lukas; Lambertova, Alena; Danes, Jan; Grusova, Gabriela

    2016-01-01

    Background Several dedicated computed tomography (CT) colonography phantoms have been described previously. Objectives To compare their pros and cons and describe the construction of a dedicated phantom that can be easily manufactured. Materials and Methods We found 15 different phantom designs by literature search and compared their advantages and disadvantages based on their description and images. We tested various materials for density and mechanical properties and constructed a phantom from polypropylene pipes (30 mm and 50 mm in diameter, 52 cm in length). Haustral folds were created by heat shaping and 39 intermediate sessile polyps with a target size of 6-10 mm and two flat lesions were created from silicone. Nine polyps were attached to a fold. The model was placed in a 30-cm barrel filled with water to simulate attenuation of human body. Attenuation of polyps was compared to intermediate polyps found in patients. Results None of the earlier colonic phantoms found in the literature incorporated all the properties that would ensure both reproducibility and validity of the model (including a rigid wall, density of the wall and polyps similar to human colon, at least two levels of distension and durability). In the present phantom, the average size of sessile polyps was 8.6 ± 0.9 mm and their density was 53 ± 24 HU. We found no significant difference in polyp density between simulated polyps in the phantom and polyps in human subjects (P = 0.70). All polyps, with the exception of one flat lesion, were detected by computer aided detection. Conclusion We constructed and validated a CT colonography phantom with correct density allowing performance of reproducible experiments. PMID:27882202

  16. Distribution of Tight Junction Proteins in Adult Human Salivary Glands

    PubMed Central

    Maria, Ola M.; Kim, Jung-Wan Martin; Gerstenhaber, Jonathan A.; Baum, Bruce J.; Tran, Simon D.

    2008-01-01

    Tight junctions (TJs) are an essential structure of fluid-secreting cells, such as those in salivary glands. Three major families of integral membrane proteins have been identified as components of the TJ: claudins, occludin, and junctional adhesion molecules (JAMs), plus the cytosolic protein zonula occludens (ZO). We have been working to develop an orally implantable artificial salivary gland that would be suitable for treating patients lacking salivary parenchymal tissue. To date, little is known about the distribution of TJ proteins in adult human salivary cells and thus what key molecular components might be desirable for the cellular component of an artificial salivary gland device. Therefore, the aim of this study was to determine the distribution of TJ proteins in human salivary glands. Salivary gland samples were obtained from 10 patients. Frozen and formalin-fixed paraffin-embedded sections were stained using IHC methods. Claudin-1 was expressed in ductal, endothelial, and ∼25% of serous cells. Claudins-2, -3, and -4 and JAM-A were expressed in both ductal and acinar cells, whereas claudin-5 was expressed only in endothelial cells. Occludin and ZO-1 were expressed in acinar, ductal, and endothelial cells. These results provide new information on TJ proteins in two major human salivary glands and should serve as a reference for future studies to assess the presence of appropriate TJ proteins in a tissue-engineered human salivary gland. (J Histochem Cytochem 56:1093–1098, 2008) PMID:18765838

  17. Preventing eternality in phantom inflation

    SciTech Connect

    Feng Chaojun; Li Xinzhou; Saridakis, Emmanuel N.

    2010-07-15

    We have investigated the necessary conditions that prevent phantom inflation from being eternal. Allowing additionally for a nonminimal coupling between the phantom field and gravity, we present the slow-climb requirements, perform an analysis of the fluctuations, and finally we extract the overall conditions that are necessary in order to prevent eternality. Furthermore, we verify our results by solving explicitly the cosmological equations in a simple example of an exponential potential, formulating the classical motion plus the stochastic effect of the fluctuations through Langevin equations. Our analysis shows that phantom inflation can be finite without the need of additional exotic mechanisms.

  18. Organ shielding and doses in Low-Earth orbit calculated for spherical and anthropomorphic phantoms

    NASA Astrophysics Data System (ADS)

    Matthiä, Daniel; Berger, Thomas; Reitz, Günther

    2013-08-01

    Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. In this work, the mean shielding of organs in the different voxel phantoms exposed to isotropic irradiation is presented as well as the corresponding depth in a water sphere. Dose rates for Low-Earth orbit from galactic cosmic rays during solar minimum conditions were calculated using the different phantoms and are compared to the results for a spherical water phantom in combination with the mean organ shielding. For the spherical water phantom the impact of different aluminium shielding between 1 g/cm2 and 100 g/cm2 was calculated. The dose equivalent rates were used to estimate the effective dose rate.

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

    PubMed Central

    Wood, Sossena; Krishnamurthy, Narayanan; Santini, Tales; Raval, Shailesh; Farhat, Nadim; Holmes, John Andy; Ibrahim, Tamer S.

    2017-01-01

    Objective The purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications. Materials and methods 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. Results 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. Conclusion 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. PMID:28806768

  20. Use of optical skin phantoms for calibration of dermatological lasers

    NASA Astrophysics Data System (ADS)

    Wróbel, M. S.; Sekowska, A.; Marchwiński, M.; Galla, S.; Cenian, A.

    2016-09-01

    A wide range of dermatological diseases can be efficiently treated using laser heating. Nevertheless, before the new laser is introduced into clinical practice, its parameters and ability to interact with human skin have to be carefully examined. In order to do that optical skin phantoms can be used. Such phantoms closely imitate the scattering and absorption properties of real human skin tissue along with its thermal properties, such as capacitance and conductivity specific heat. We have fabricated a range of optical tissue phantoms based on polyvinylchloride-plastisol PVC-P with varying optical properties, including the absorption, scattering and density of the matrix material. We have utilized a pre-clinical dermatological laser system with a 975 nm diode laser module. A range of laser settings were tested, such as laser pulse duration, laser power and number of pulses. We have studied laser irradiation efficiency on fabricated optical tissue phantoms. Measurements of the temporal and spatial temperature distribution on the phantoms' surface were performed using thermographic imaging. The comparison of results between tissues' and phantoms' optical and thermal response prove that they can be used for approximate evaluation of laser heating efficiency. This study presents a viable approach for calibration of dermatological lasers which can be utilized in practice.

  1. Neuropeptide Y in the adult and fetal human pineal gland.

    PubMed

    Møller, Morten; Phansuwan-Pujito, Pansiri; Badiu, Corin

    2014-01-01

    Neuropeptide Y was isolated from the porcine brain in 1982 and shown to be colocalized with noradrenaline in sympathetic nerve terminals. The peptide has been demonstrated to be present in sympathetic nerve fibers innervating the pineal gland in many mammalian species. In this investigation, we show by use of immunohistochemistry that neuropeptide Y is present in nerve fibers of the adult human pineal gland. The fibers are classical neuropeptidergic fibers endowed with large boutons en passage and primarily located in a perifollicular position with some fibers entering the pineal parenchyma inside the follicle. The distance from the immunoreactive terminals to the pinealocytes indicates a modulatory function of neuropeptide Y for pineal physiology. Some of the immunoreactive fibers might originate from neurons located in the brain and be a part of the central innervation of the pineal gland. In a series of human fetuses, neuropeptide Y-containing nerve fibers was present and could be detected as early as in the pineal of four- to five-month-old fetuses. This early innervation of the human pineal is different from most rodents, where the innervation starts postnatally.

  2. Phantom pain after eye amputation.

    PubMed

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

    2011-02-01

    To characterize the quality of phantom pain, its intensity and frequency following eye amputation. Possible triggers and relievers of phantom pain are investigated. The hospital database was searched using surgery codes for patients who received ocular evisceration, enucleation, orbital exenteration or secondary implantation of an orbital implant in the period between 1993 and 2003. A total of 267 patients were identified and invited to participate; of these, 173 agreed to participate. These patients' medical records were reviewed. A structured interview focusing on pain was conducted by a trained interviewer. 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 pain was reported to be of three different qualities: (i) cutting, penetrating, gnawing or oppressive (n = 19); (ii) radiating, zapping or shooting (n = 8); (iii) superficial burning or stinging (n = 5); or a mixture of these different pain qualities (n = 7). The median intensity on a visual analogue 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.   Phantom pain after eye amputation is relatively common. The pain appears to be similar to the phantom pain suffered by limb amputees. Patients should be informed about this potential complication before surgery. © 2010 The Authors. Acta Ophthalmologica © 2010 Acta Ophthalmologica Scandinavica Foundation.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Organosilicon phantom for photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Avigo, Cinzia; Di Lascio, Nicole; Armanetti, Paolo; Kusmic, Claudia; Cavigli, Lucia; Ratto, Fulvio; Meucci, Sandro; Masciullo, Cecilia; Cecchini, Marco; Pini, Roberto; Faita, Francesco; Menichetti, Luca

    2015-04-01

    Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-to-noise ratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

  5. Phantom stars and topology change

    SciTech Connect

    DeBenedictis, Andrew; Garattini, Remo; Lobo, Francisco S. N.

    2008-11-15

    In this work, we consider time-dependent dark-energy star models, with an evolving parameter {omega} crossing the phantom divide {omega}=-1. Once in the phantom regime, the null energy condition is violated, which physically implies that the negative radial pressure exceeds the energy density. Therefore, an enormous negative pressure in the center may, in principle, imply a topology change, consequently opening up a tunnel and converting the dark-energy star into a wormhole. The criteria for this topology change are discussed and, in particular, we consider a Casimir energy approach involving quasilocal energy difference calculations that may reflect or measure the occurrence of a topology change. We denote these exotic geometries consisting of dark-energy stars (in the phantom regime) and phantom wormholes as phantom stars. The final product of this topological change, namely, phantom wormholes, have far-reaching physical and cosmological implications, as in addition to being used for interstellar shortcuts, an absurdly advanced civilization may manipulate these geometries to induce closed timelike curves, consequently violating causality.

  6. Organosilicon phantom for photoacoustic imaging.

    PubMed

    Avigo, Cinzia; Di Lascio, Nicole; Armanetti, Paolo; Kusmic, Claudia; Cavigli, Lucia; Ratto, Fulvio; Meucci, Sandro; Masciullo, Cecilia; Cecchini, Marco; Pini, Roberto; Faita, Francesco; Menichetti, Luca

    2015-04-01

    Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-tonoiseratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

  7. Realistic Analytical Polyhedral MRI Phantoms

    PubMed Central

    Ngo, Tri M.; Fung, George S. K.; Han, Shuo; Chen, Min; Prince, Jerry L.; Tsui, Benjamin M. W.; McVeigh, Elliot R.; Herzka, Daniel A.

    2015-01-01

    Purpose Analytical phantoms have closed form Fourier transform expressions and are used to simulate MRI acquisitions. Existing 3D analytical phantoms are unable to accurately model shapes of biomedical interest. It is demonstrated that polyhedral analytical phantoms have closed form Fourier transform expressions and can accurately represent 3D biomedical shapes. Theory The derivations of the Fourier transform of a polygon and polyhedron are presented. Methods The Fourier transform of a polyhedron was implemented and its accuracy in representing faceted and smooth surfaces was characterized. Realistic anthropomorphic polyhedral brain and torso phantoms were constructed and their use in simulated 3D/2D MRI acquisitions was described. Results Using polyhedra, the Fourier transform of faceted shapes can be computed to within machine precision. Smooth surfaces can be approximated with increasing accuracy by increasing the number of facets in the polyhedron; the additional accumulated numerical imprecision of the Fourier transform of polyhedra with many faces remained small. Simulations of 3D/2D brain and 2D torso cine acquisitions produced realistic reconstructions free of high frequency edge aliasing as compared to equivalent voxelized/rasterized phantoms. Conclusion Analytical polyhedral phantoms are easy to construct and can accurately simulate shapes of biomedical interest. PMID:26479724

  8. Realistic analytical polyhedral MRI phantoms.

    PubMed

    Ngo, Tri M; Fung, George S K; Han, Shuo; Chen, Min; Prince, Jerry L; Tsui, Benjamin M W; McVeigh, Elliot R; Herzka, Daniel A

    2016-08-01

    Analytical phantoms have closed form Fourier transform expressions and are used to simulate MRI acquisitions. Existing three-dimensional (3D) analytical phantoms are unable to accurately model shapes of biomedical interest. The goal of this study was to demonstrate that polyhedral analytical phantoms have closed form Fourier transform expressions and can accurately represent 3D biomedical shapes. The Fourier transform of a polyhedron was implemented and its accuracy in representing faceted and smooth surfaces was characterized. Realistic anthropomorphic polyhedral brain and torso phantoms were constructed and their use in simulated 3D and two-dimensional (2D) MRI acquisitions was described. Using polyhedra, the Fourier transform of faceted shapes can be computed to within machine precision. Smooth surfaces can be approximated with increasing accuracy by increasing the number of facets in the polyhedron; the additional accumulated numerical imprecision of the Fourier transform of polyhedra with many faces remained small. Simulations of 3D and 2D brain and 2D torso cine acquisitions produced realistic reconstructions free of high frequency edge aliasing compared with equivalent voxelized/rasterized phantoms. Analytical polyhedral phantoms are easy to construct and can accurately simulate shapes of biomedical interest. Magn Reson Med 76:663-678, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  9. Automatic Synthesis of Anthropomorphic Pulmonary CT Phantoms

    PubMed Central

    Jimenez-Carretero, Daniel; San Jose Estepar, Raul; Diaz Cacio, Mario; Ledesma-Carbayo, Maria J.

    2016-01-01

    The great density and structural complexity of pulmonary vessels and airways impose limitations on the generation of accurate reference standards, which are critical in training and in the validation of image processing methods for features such as pulmonary vessel segmentation or artery–vein (AV) separations. The design of synthetic computed tomography (CT) images of the lung could overcome these difficulties by providing a database of pseudorealistic cases in a constrained and controlled scenario where each part of the image is differentiated unequivocally. This work demonstrates a complete framework to generate computational anthropomorphic CT phantoms of the human lung automatically. Starting from biological and image-based knowledge about the topology and relationships between structures, the system is able to generate synthetic pulmonary arteries, veins, and airways using iterative growth methods that can be merged into a final simulated lung with realistic features. A dataset of 24 labeled anthropomorphic pulmonary CT phantoms were synthesized with the proposed system. Visual examination and quantitative measurements of intensity distributions, dispersion of structures and relationships between pulmonary air and blood flow systems show good correspondence between real and synthetic lungs (p > 0.05 with low Cohen’s d effect size and AUC values), supporting the potentiality of the tool and the usefulness of the generated phantoms in the biomedical image processing field. PMID:26731653

  10. Sex Determination of Adult Human Maxillary Sinuses on Panoramic Radiographs

    PubMed Central

    Leao de Queiroz, Cristhiane; Terada, Andrea Sayuri Silveira Dias; Dezem, Thais Uenoyama; Gomes de Araújo, Lais; Galo, Rodrigo; Oliveira-Santos, Christiano

    2016-01-01

    Absract The purpose of this study was to evaluate dimensions of adult human maxillary sinuses on panoramic radiographs and their possible application on the sex determination for forensic purposes. The sample comprised 64 database panoramic radiographs from individuals aged 20 years or older (32 male and 32 female subjects), with complete permanent dentition (or absence of third molars). One examiner measured the width and height of the right and left maxillary sinuses using the software Image J 1.47v (National Institutes of Health, Bethesda, USA). Measurements were repeated to calculate intra-observer agreement. Chi-Square test, Kappa, ANOVA and T-Student were used for results analysis for p≤ 0.05. Intra-observer agreement with correlation Kappa ranged between 0.38 and 0.96. For female subjects, the mean height and width of the left maxillary sinus were 28.7856mm and 44.6178mm, respectively. And right maxillary sinus was 27.7163mm for height and 45.1850mm for width. Male subjects were found to have the mean height and width of the left maxillary sinus 30.9981mm and 48.7753mm, respectively. And right maxillary sinus was 30.7403mm for height and 48.5753mm for width. There was a statistically significant difference in the height and width of maxillary sinuses between males and females. It can be concluded that maxillary sinuses height and width on panoramic radiographs can be used to determine the gender of adult human subjects. PMID:27847394

  11. The adult human pubic symphysis: a systematic review

    PubMed Central

    Becker, Ines; Woodley, Stephanie J; Stringer, Mark D

    2010-01-01

    The pubic symphysis is a unique joint consisting of a fibrocartilaginous disc sandwiched between the articular surfaces of the pubic bones. It resists tensile, shearing and compressive forces and is capable of a small amount of movement under physiological conditions in most adults (up to 2 mm shift and 1° rotation). During pregnancy, circulating hormones such as relaxin induce resorption of the symphyseal margins and structural changes in the fibrocartilaginous disc, increasing symphyseal width and mobility. This systematic review of the English, German and French literature focuses on the normal anatomy of the adult human pubic symphysis. Although scientific studies of the joint have yielded useful descriptive data, comparison of results is hampered by imprecise methodology and/or poorly controlled studies. Several aspects of the anatomy of the pubic symphysis remain unknown or unclear: the precise attachments of surrounding ligaments and muscles; the arrangement of connective tissue fibres within the interpubic disc and the origin, structure and function of its associated interpubic cleft; the biomechanical consequences of sexual dimorphism; potential ethnic variations in morphology; and its precise innervation and blood supply. These deficiencies hinder our understanding of the normal form and function of the joint, which is particularly relevant when attempting to understand the mechanisms underlying pregnancy-related pubic symphyseal pain, a neglected and relatively common cause of pubic pain. A better understanding of the normal anatomy of the human pubic symphysis should improve our understanding of such problems and contribute to better treatments for patients suffering from symphyseal pain and dysfunction. PMID:20840351

  12. Sex Determination of Adult Human Maxillary Sinuses on Panoramic Radiographs.

    PubMed

    Leao de Queiroz, Cristhiane; Terada, Andrea Sayuri Silveira Dias; Dezem, Thais Uenoyama; Gomes de Araújo, Lais; Galo, Rodrigo; Oliveira-Santos, Christiano; Alves da Silva, Ricardo Henrique

    2016-09-01

    The purpose of this study was to evaluate dimensions of adult human maxillary sinuses on panoramic radiographs and their possible application on the sex determination for forensic purposes. The sample comprised 64 database panoramic radiographs from individuals aged 20 years or older (32 male and 32 female subjects), with complete permanent dentition (or absence of third molars). One examiner measured the width and height of the right and left maxillary sinuses using the software Image J 1.47v (National Institutes of Health, Bethesda, USA). Measurements were repeated to calculate intra-observer agreement. Chi-Square test, Kappa, ANOVA and T-Student were used for results analysis for p≤ 0.05. Intra-observer agreement with correlation Kappa ranged between 0.38 and 0.96. For female subjects, the mean height and width of the left maxillary sinus were 28.7856mm and 44.6178mm, respectively. And right maxillary sinus was 27.7163mm for height and 45.1850mm for width. Male subjects were found to have the mean height and width of the left maxillary sinus 30.9981mm and 48.7753mm, respectively. And right maxillary sinus was 30.7403mm for height and 48.5753mm for width. There was a statistically significant difference in the height and width of maxillary sinuses between males and females. It can be concluded that maxillary sinuses height and width on panoramic radiographs can be used to determine the gender of adult human subjects.

  13. Accuracy of phase contrast, black-blood, and bright-blood pulse sequences for measuring compliance and distensibility coefficients in a human-tissue mimicking phantom.

    PubMed

    Taviani, Valentina; Patterson, Andrew J; Worters, Pauline; Sutcliffe, Michael P F; Graves, Martin J; Gillard, Jonathan H

    2010-01-01

    To assess the accuracy of MR-derived luminal diameter variations and its implications for compliance (CC) and distensibility coefficients (DC) by comparison with high-resolution digital photography (HRDP) in a tissue-mimicking phantom with pulsatile flow. Diameters, CC, and DC extracted using cine phase-contrast (CPC), cine bright-blood (CBrB), and a cine black-blood (CBB) sequence were compared. The diameter in the left-right direction was compared against HRDP, as the gold-standard. The experiments were performed using 256(2) and 512(2) matrix sizes. Bland-Altman analysis was performed to compare each sequence with the gold-standard in terms of diameter changes over the simulated cardiac cycle. The bias and 95% limits of agreement (LOA) for CBB and CBrB were comparable. The bias for CPC was larger, however, the LOA were comparable. Increasing spatial resolution improved agreement with HRDP for all sequences. CBrB-derived CC and DC were within 3% of the high resolution CBB values while CPC CC and DC were underestimated but still within 11%. CPC images were found to underestimate the luminal area over the cardiac cycle. CBrB-derived diameters were more accurate in diastole while CBB-derived diameters gave the best results in systole. CC and DC varied depending on the pulse sequence. (c) 2009 Wiley-Liss, Inc.

  14. Phantom black holes and sigma models

    SciTech Connect

    Azreg-Aienou, Mustapha; Clement, Gerard; Fabris, Julio C.; Rodrigues, Manuel E.

    2011-06-15

    We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling constant. We also discuss the three-dimensional gravitating sigma models obtained by reduction of phantom Einstein-Maxwell, phantom Kaluza-Klein and phantom Einstein-Maxwell-dilaton-axion theories. In each case, we generate by group transformations phantom charged black hole solutions from a neutral seed.

  15. Quality assessment of digital X-ray chest images using an anthropomorphic chest phantom

    NASA Astrophysics Data System (ADS)

    Vodovatov, A. V.; Kamishanskaya, I. G.; Drozdov, A. A.; Bernhardsson, C.

    2017-02-01

    The current study is focused on determining the optimal tube voltage for the conventional X-ray digital chest screening examinations, using a visual grading analysis method. Chest images of an anthropomorphic phantom were acquired in posterior-anterior projection on four digital X-ray units with different detector types. X-ray images obtained with an anthropomorphic phantom were accepted by the radiologists as corresponding to a normal human anatomy, hence allowing using phantoms in image quality trials without limitations.

  16. Heterogeneous Breast Phantom Development for Microwave Imaging Using Regression Models

    PubMed Central

    Hahn, Camerin; Noghanian, Sima

    2012-01-01

    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. PMID:22550473

  17. A biological phantom for evaluation of CT image reconstruction algorithms

    NASA Astrophysics Data System (ADS)

    Cammin, J.; Fung, G. S. K.; Fishman, E. K.; Siewerdsen, J. H.; Stayman, J. W.; Taguchi, K.

    2014-03-01

    In recent years, iterative algorithms have become popular in diagnostic CT imaging to reduce noise or radiation dose to the patient. The non-linear nature of these algorithms leads to non-linearities in the imaging chain. However, the methods to assess the performance of CT imaging systems were developed assuming the linear process of filtered backprojection (FBP). Those methods may not be suitable any longer when applied to non-linear systems. In order to evaluate the imaging performance, a phantom is typically scanned and the image quality is measured using various indices. For reasons of practicality, cost, and durability, those phantoms often consist of simple water containers with uniform cylinder inserts. However, these phantoms do not represent the rich structure and patterns of real tissue accurately. As a result, the measured image quality or detectability performance for lesions may not reflect the performance on clinical images. The discrepancy between estimated and real performance may be even larger for iterative methods which sometimes produce "plastic-like", patchy images with homogeneous patterns. Consequently, more realistic phantoms should be used to assess the performance of iterative algorithms. We designed and constructed a biological phantom consisting of porcine organs and tissue that models a human abdomen, including liver lesions. We scanned the phantom on a clinical CT scanner and compared basic image quality indices between filtered backprojection and an iterative reconstruction algorithm.

  18. Quantifying Backscatter Anisotropy Using the Reference Phantom Method.

    PubMed

    Guerrero, Quinton W; Rosado-Mendez, Ivan M; Drehfal, Lindsey C; Feltovich, Helen; Hall, Timothy J

    2017-07-01

    Acoustic properties can be exploited to infer and evaluate tissue microstructure. However, common assumptions are that the medium of interest is homogeneous and isotropic, and that its underlying physical properties cause diffuse scattering. In this paper, we describe how we developed and tested novel parameters designed to address isotropy/anisotropy in backscattered echo signal power in complex biological tissues. Specifically, we explored isotropy/anisotropy in backscattered power in isotropic phantoms (spherical glass beads), an anisotropic phantom (dialysis phantom with rodlike fibers), and an in vivo human tissue with well-described anisotropy (bicep muscle). Our approach uses the reference phantom method to compensate for system transfer and diffraction losses when electronically beamsteering a linear array transducer. We define three parameters to quantify the presence and orientation of anisotropic scatterers, as well as address magnitude of anisotropy. We found that these parameters can detect and sense the degree of anisotropy in backscatter in both phantoms and bicep muscle. Bias of the summary anisotropy parameters, induced through a speed of sound mismatch of sample media and reference phantom, was less than 0.2 dB if the speed of sound was within ±20 m/s of the sample media. In summary, these new parameters may be useful for testing the assumption of isotropy as well as providing more detailed information about the underlying microstructural sources of backscatter in complex biological tissues.

  19. Ossified Ligamentum Longitudinale Anterius in Adult Human Dry Vertebrae

    PubMed Central

    Venumadhav, Nelluri; KS, Siddaraju

    2014-01-01

    Background: The ligamentum longitudinale anterius is a broad and strong band of fibrous tissue that runs along the anterior surfaces of the bodies of the vertebrae. Aim: The study was undertaken to evaluate the incidence of ossified ligamentum longitudinale anterius in adult dry human vertebra. Materials and Methods: This study was carried out on 95 sets of dry human vertebral columns irrespective of age and sex at Mayo Institute of Medical Sciences- Barabanki,-UP, Melaka Manipal Medical College-Manipal University and Department of Anatomy, KMCT Medical College, Manassery- Calicut, India. All the sets of vertebral columns were macroscopically inspected for the ossified ligamentum longitudinale anterius. Results: It was observed that out of 95 sets of vertebral columns, 27 (28.42%) vertebral columns showed ossification. Out of 27 vertebral columns, 17 (17.89%) vertebral columns showed segmental type of ossification, 2 (2.11%) vertebral columns showed continuous type of ossification and 8 (8.42%) vertebral columns showed mixed type of ossification at different vertebral level. Conclusion: Such type of ossification will affect the biomechanics of the spine and may result in stiff neck, low back pain, dysphagia, odynophagia, compression of the brachial plexus, aphonia, immobility or mucosal thickening of larynx. Hence, knowledge of such abnormalities should be kept in mind to minimise serious complications in any surgical intervention or investigative procedures in the region. PMID:25302180

  20. A biokinetic model for systemic technetium in adult humans

    DOE PAGES

    Leggett, Richard Wayne; Giussani, Augusto

    2015-04-10

    The International Commission on Radiological Protection (ICRP) currently is updating its biokinetic and dosimetric models for internally deposited radionuclides. Technetium (Tc), the lightest element that exists only in radioactive form, has two important isotopes from the standpoint of potential risk to humans: the long-lived isotope 99Tm(T1/2=2.1x105 y) is present in high concentration in nuclear waste, and the short-lived isotope 99mTc (T1/2=6.02 h) is the most commonly used radionuclide in diagnostic nuclear medicine. This paper reviews data on the biological behavior of technetium and proposes a biokinetic model for systemic technetium in the adult human body for use in radiation protection.more » Compared with the ICRP s current occupational model for systemic technetium, the proposed model provides a more realistic description of the paths of movement of technetium in the body; provides greater consistency with experimental and medical data; and, for most radiosensitive organs, yields substantially different estimates of cumulative activity (total radioactive decays within the organ) following uptake of 99Tm or 99mTc to blood.« less

  1. Comprehensive cellular-resolution atlas of the adult human brain.

    PubMed

    Ding, Song-Lin; Royall, Joshua J; Sunkin, Susan M; Ng, Lydia; Facer, Benjamin A C; Lesnar, Phil; Guillozet-Bongaarts, Angie; McMurray, Bergen; Szafer, Aaron; Dolbeare, Tim A; Stevens, Allison; Tirrell, Lee; Benner, Thomas; Caldejon, Shiella; Dalley, Rachel A; Dee, Nick; Lau, Christopher; Nyhus, Julie; Reding, Melissa; Riley, Zackery L; Sandman, David; Shen, Elaine; van der Kouwe, Andre; Varjabedian, Ani; Write, Michelle; Zollei, Lilla; Dang, Chinh; Knowles, James A; Koch, Christof; Phillips, John W; Sestan, Nenad; Wohnoutka, Paul; Zielke, H Ronald; Hohmann, John G; Jones, Allan R; Bernard, Amy; Hawrylycz, Michael J; Hof, Patrick R; Fischl, Bruce; Lein, Ed S

    2016-11-01

    Detailed anatomical understanding of the human brain is essential for unraveling its functional architecture, yet current reference atlases have major limitations such as lack of whole-brain coverage, relatively low image resolution, and sparse structural annotation. We present the first digital human brain atlas to incorporate neuroimaging, high-resolution histology, and chemoarchitecture across a complete adult female brain, consisting of magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and 1,356 large-format cellular resolution (1 µm/pixel) Nissl and immunohistochemistry anatomical plates. The atlas is comprehensively annotated for 862 structures, including 117 white matter tracts and several novel cyto- and chemoarchitecturally defined structures, and these annotations were transferred onto the matching MRI dataset. Neocortical delineations were done for sulci, gyri, and modified Brodmann areas to link macroscopic anatomical and microscopic cytoarchitectural parcellations. Correlated neuroimaging and histological structural delineation allowed fine feature identification in MRI data and subsequent structural identification in MRI data from other brains. This interactive online digital atlas is integrated with existing Allen Institute for Brain Science gene expression atlases and is publicly accessible as a resource for the neuroscience community. J. Comp. Neurol. 524:3127-3481, 2016. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. Copyright © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

  2. A biokinetic model for systemic technetium in adult humans

    SciTech Connect

    Leggett, Richard Wayne; Giussani, Augusto

    2015-04-10

    The International Commission on Radiological Protection (ICRP) currently is updating its biokinetic and dosimetric models for internally deposited radionuclides. Technetium (Tc), the lightest element that exists only in radioactive form, has two important isotopes from the standpoint of potential risk to humans: the long-lived isotope 99Tm(T1/2=2.1x105 y) is present in high concentration in nuclear waste, and the short-lived isotope 99mTc (T1/2=6.02 h) is the most commonly used radionuclide in diagnostic nuclear medicine. This paper reviews data on the biological behavior of technetium and proposes a biokinetic model for systemic technetium in the adult human body for use in radiation protection. Compared with the ICRP s current occupational model for systemic technetium, the proposed model provides a more realistic description of the paths of movement of technetium in the body; provides greater consistency with experimental and medical data; and, for most radiosensitive organs, yields substantially different estimates of cumulative activity (total radioactive decays within the organ) following uptake of 99Tm or 99mTc to blood.

  3. An anatomically comprehensive atlas of the adult human brain transcriptome

    PubMed Central

    Guillozet-Bongaarts, Angela L.; Shen, Elaine H.; Ng, Lydia; Miller, Jeremy A.; van de Lagemaat, Louie N.; Smith, Kimberly A.; Ebbert, Amanda; Riley, Zackery L.; Abajian, Chris; Beckmann, Christian F.; Bernard, Amy; Bertagnolli, Darren; Boe, Andrew F.; Cartagena, Preston M.; Chakravarty, M. Mallar; Chapin, Mike; Chong, Jimmy; Dalley, Rachel A.; David Daly, Barry; Dang, Chinh; Datta, Suvro; Dee, Nick; Dolbeare, Tim A.; Faber, Vance; Feng, David; Fowler, David R.; Goldy, Jeff; Gregor, Benjamin W.; Haradon, Zeb; Haynor, David R.; Hohmann, John G.; Horvath, Steve; Howard, Robert E.; Jeromin, Andreas; Jochim, Jayson M.; Kinnunen, Marty; Lau, Christopher; Lazarz, Evan T.; Lee, Changkyu; Lemon, Tracy A.; Li, Ling; Li, Yang; Morris, John A.; Overly, Caroline C.; Parker, Patrick D.; Parry, Sheana E.; Reding, Melissa; Royall, Joshua J.; Schulkin, Jay; Sequeira, Pedro Adolfo; Slaughterbeck, Clifford R.; Smith, Simon C.; Sodt, Andy J.; Sunkin, Susan M.; Swanson, Beryl E.; Vawter, Marquis P.; Williams, Derric; Wohnoutka, Paul; Zielke, H. Ronald; Geschwind, Daniel H.; Hof, Patrick R.; Smith, Stephen M.; Koch, Christof; Grant, Seth G. N.; Jones, Allan R.

    2014-01-01

    Neuroanatomically precise, genome-wide maps of transcript distributions are critical resources to complement genomic sequence data and to correlate functional and genetic brain architecture. Here we describe the generation and analysis of a transcriptional atlas of the adult human brain, comprising extensive histological analysis and comprehensive microarray profiling of ~900 neuroanatomically precise subdivisions in two individuals. Transcriptional regulation varies enormously by anatomical location, with different regions and their constituent cell types displaying robust molecular signatures that are highly conserved between individuals. Analysis of differential gene expression and gene co-expression relationships demonstrates that brain-wide variation strongly reflects the distributions of major cell classes such as neurons, oligodendrocytes, astrocytes and microglia. Local neighbourhood relationships between fine anatomical subdivisions are associated with discrete neuronal subtypes and genes involved with synaptic transmission. The neocortex displays a relatively homogeneous transcriptional pattern, but with distinct features associated selectively with primary sensorimotor cortices and with enriched frontal lobe expression. Notably, the spatial topography of the neocortex is strongly reflected in its molecular topography— the closer two cortical regions, the more similar their transcriptomes. This freely accessible online data resource forms a high-resolution transcriptional baseline for neurogenetic studies of normal and abnormal human brain function. PMID:22996553

  4. Age-associated changes in microvasculature of human adult testis.

    PubMed

    Takizawa, T; Hatakeyama, S

    1978-07-01

    Age-associated architectural changes of the human testicular microvasculature from 70 autopsy cases were stereoscopically examined with a silicone-rubber injection technique. In the testis of a young subject, the interlobular main arteries run straight. The coiling phenomena of the interlobular centripetal or centrifugal arteries, which are commonly seen in adult testis, have been so far considered as physiological transformation of the vasculature. It was confirmed that the coiling changes in the interlobular main arteries of the human testis appear as an age-dependent alteration of the vasculature closely related to the volume of the gland. The practical importance of the spirallin or coiling of arteries is that it results in a considerable reduction of blood flow. The age-related coiling of the interlobular arteries is virtually accompanied by varying degrees of collapse of the peritubular capillary networks. The reduction of blood supply to the seminiferous tubules plays an active role in promoting aging of the testis. These stereoscopical observations of age-related transfiguration of testicular microvasculature were ascertained also by histometrical examinations.

  5. Comprehensive cellular‐resolution atlas of the adult human brain

    PubMed Central

    Royall, Joshua J.; Sunkin, Susan M.; Ng, Lydia; Facer, Benjamin A.C.; Lesnar, Phil; Guillozet‐Bongaarts, Angie; McMurray, Bergen; Szafer, Aaron; Dolbeare, Tim A.; Stevens, Allison; Tirrell, Lee; Benner, Thomas; Caldejon, Shiella; Dalley, Rachel A.; Dee, Nick; Lau, Christopher; Nyhus, Julie; Reding, Melissa; Riley, Zackery L.; Sandman, David; Shen, Elaine; van der Kouwe, Andre; Varjabedian, Ani; Write, Michelle; Zollei, Lilla; Dang, Chinh; Knowles, James A.; Koch, Christof; Phillips, John W.; Sestan, Nenad; Wohnoutka, Paul; Zielke, H. Ronald; Hohmann, John G.; Jones, Allan R.; Bernard, Amy; Hawrylycz, Michael J.; Hof, Patrick R.; Fischl, Bruce

    2016-01-01

    ABSTRACT Detailed anatomical understanding of the human brain is essential for unraveling its functional architecture, yet current reference atlases have major limitations such as lack of whole‐brain coverage, relatively low image resolution, and sparse structural annotation. We present the first digital human brain atlas to incorporate neuroimaging, high‐resolution histology, and chemoarchitecture across a complete adult female brain, consisting of magnetic resonance imaging (MRI), diffusion‐weighted imaging (DWI), and 1,356 large‐format cellular resolution (1 µm/pixel) Nissl and immunohistochemistry anatomical plates. The atlas is comprehensively annotated for 862 structures, including 117 white matter tracts and several novel cyto‐ and chemoarchitecturally defined structures, and these annotations were transferred onto the matching MRI dataset. Neocortical delineations were done for sulci, gyri, and modified Brodmann areas to link macroscopic anatomical and microscopic cytoarchitectural parcellations. Correlated neuroimaging and histological structural delineation allowed fine feature identification in MRI data and subsequent structural identification in MRI data from other brains. This interactive online digital atlas is integrated with existing Allen Institute for Brain Science gene expression atlases and is publicly accessible as a resource for the neuroscience community. J. Comp. Neurol. 524:3127–3481, 2016. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. PMID:27418273

  6. Ossified ligamentum longitudinale anterius in adult human dry vertebrae.

    PubMed

    Kosuri, Kalyan Chakravarthi; Venumadhav, Nelluri; Ks, Siddaraju

    2014-08-01

    The ligamentum longitudinale anterius is a broad and strong band of fibrous tissue that runs along the anterior surfaces of the bodies of the vertebrae. The study was undertaken to evaluate the incidence of ossified ligamentum longitudinale anterius in adult dry human vertebra. This study was carried out on 95 sets of dry human vertebral columns irrespective of age and sex at Mayo Institute of Medical Sciences- Barabanki,-UP, Melaka Manipal Medical College-Manipal University and Department of Anatomy, KMCT Medical College, Manassery- Calicut, India. All the sets of vertebral columns were macroscopically inspected for the ossified ligamentum longitudinale anterius. It was observed that out of 95 sets of vertebral columns, 27 (28.42%) vertebral columns showed ossification. Out of 27 vertebral columns, 17 (17.89%) vertebral columns showed segmental type of ossification, 2 (2.11%) vertebral columns showed continuous type of ossification and 8 (8.42%) vertebral columns showed mixed type of ossification at different vertebral level. Such type of ossification will affect the biomechanics of the spine and may result in stiff neck, low back pain, dysphagia, odynophagia, compression of the brachial plexus, aphonia, immobility or mucosal thickening of larynx. Hence, knowledge of such abnormalities should be kept in mind to minimise serious complications in any surgical intervention or investigative procedures in the region.

  7. The Effect of Body Mass on Outdoor Adult Human Decomposition.

    PubMed

    Roberts, Lindsey G; Spencer, Jessica R; Dabbs, Gretchen R

    2017-02-23

    Forensic taphonomy explores factors impacting human decomposition. This study investigated the effect of body mass on the rate and pattern of adult human decomposition. Nine males and three females aged 49-95 years ranging in mass from 73 to 159 kg who were donated to the Complex for Forensic Anthropology Research between December 2012 and September 2015 were included in this study. Kelvin accumulated degree days (KADD) were used to assess the thermal energy required for subjects to reach several total body score (TBS) thresholds: early decomposition (TBS ≥6.0), TBS ≥12.5, advanced decomposition (TBS ≥19.0), TBS ≥23.0, and skeletonization (TBS ≥27.0). Results indicate no significant correlation between body mass and KADD at any TBS threshold. Body mass accounted for up to 24.0% of variation in decomposition rate depending on stage, and minor differences in decomposition pattern were observed. Body mass likely has a minimal impact on postmortem interval estimation.

  8. Adult human liver mesenchymal progenitor cells express phenylalanine hydroxylase.

    PubMed

    Baruteau, Julien; Nyabi, Omar; Najimi, Mustapha; Fauvart, Maarten; Sokal, Etienne

    2014-09-01

    Phenylketonuria (PKU) is one of the most prevalent inherited metabolic diseases and is accountable for a severe encephalopathy by progressive intoxication of the brain by phenylalanine. This results from an ineffective L-phenylalanine hydroxylase enzyme (PAH) due to a mutated phenylalanine hydroxylase (PAH) gene. Neonatal screening programs allow an early dietetic treatment with restrictive phenylalanine intake. This diet prevents most of the neuropsychological disabilities but remains challenging for lifelong compliance. Adult-derived human liver progenitor cells (ADHLPC) are a pool of precursors that can differentiate into hepatocytes. We aim to study PAH expression and PAH activity in a differenciated ADHLPC. ADHLPC were isolated from human hepatocyte primary culture of two different donors and differenciated under specific culture conditions. We demonstrated the high expression of PAH and a large increase of PAH activity in differenciated LPC. The age of the donor, the cellular viability after liver digestion and cryopreservation affects PAH activity. ADHLPC might therefore be considered as a suitable source for cell therapy in PKU.

  9. On the dose sensitivity of a new CDMAM phantom

    NASA Astrophysics Data System (ADS)

    Figl, M.; Semturs, F.; Kaar, M.; Hoffmann, R.; Floor-Westerdijk, M.; van der Burght, R.; Homolka, P.; Hummel, J.

    2015-05-01

    For the technical quality assurance of breast cancer screening protocols several phantoms have been developed. Their dose sensitivity is a common topic often discussed in literature. The European protocol for the quality control of the physical and technical aspects of mammography screening suggests a contrast-detail phantom like the CDMAM phantom (Artinis Medical Systems, Elst, NL). The CDMAM 3.4 was tested with respect to its dose sensitivity and compared to other phantoms in a recent paper. The CDMAM 4.0 phantom provides other disc diameters and thicknesses adapted more closely to the image quality found in modern mammography systems. This motivates a comparison of the two generations using the same exposure parameters. We varied the time-current (mAs) within a range of clinically used values (40-140 mAs). All evaluations were done using automatic evaluation software provided by Artinis (for CDMAM 4.0) and the National Coordinating Centre for the Physics of Mammography, Guildford UK (CDMAM 3.4). We compared the relative dose sensitivity with respect to the different diameters and also computed the IQFinv parameter, which averages over the diameters as suggested in the manual for the phantom. The IQFinv parameter linearly depends on dose for both phantoms. The CDMAM 4.0 shows a more monotonous dependence on dose, the total variation of the threshold thicknesses as functions of the dose are significantly smaller than with the CDMAM 3.4. As the automatic evaluation shows rather different threshold thicknesses for the two phantoms, conversion factors for human to automatic readout have to be adapted.

  10. Comparison of organ doses for patients undergoing balloon brachytherapy of the breast with HDR 192Ir or electronic sources using monte carlo simulations in a heterogeneous human phantom.

    PubMed

    Mille, Matthew M; Xu, X George; Rivard, Mark J

    2010-02-01

    Accelerated partial breast irradiation via interstitial balloon brachytherapy is a fast and effective treatment method for certain early stage breast cancers. The radiation can be delivered using a conventional high-dose rate (HDR) 192Ir gamma-emitting source or a novel electronic brachytherapy (eBx) source which uses lower energy x rays that do not penetrate as far within the patient. A previous study [A. Dickler, M. C. Kirk, N. Seif, K. Griem, K. Dowlatshahi, D. Francescatti, and R. A. Abrams, "A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy," Brachytherapy 6, 164-168 (2007)] showed that the target dose is similar for HDR 192Ir and eBx. This study compares these sources based on the dose received by healthy organs and tissues away from the treatment site. A virtual patient with left breast cancer was represented by a whole-body, tissue-heterogeneous female voxel phantom. Monte Carlo methods were used to calculate the dose to healthy organs in a virtual patient undergoing balloon brachytherapy of the left breast with HDR 192Ir or eBx sources. The dose-volume histograms for a few organs which received large doses were also calculated. Additional simulations were performed with all tissues in the phantom defined as water to study the effect of tissue inhomogeneities. For both HDR 192Ir and eBx, the largest mean organ doses were received by the ribs, thymus gland, left lung, heart, and sternum which were close to the brachytherapy source in the left breast, eBx yielded mean healthy organ doses that were more than a factor of approximately 1.4 smaller than for HDR 192Ir for all organs considered, except for the three closest ribs. Excluding these ribs, the average and median dose-reduction factors were approximately 28 and approximately 11, respectively. The volume distribution of doses in nearby soft tissue organs that were outside the PTV were also improved with eBx. However, the maximum dose to the closest

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

    NASA Astrophysics Data System (ADS)

    Wydra, A.; Maev, R. Gr

    2013-11-01

    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.

  12. Vortex-ring mixing as a measure of diastolic function of the human heart: Phantom validation and initial observations in healthy volunteers and patients with heart failure.

    PubMed

    Töger, Johannes; Kanski, Mikael; Arvidsson, Per M; Carlsson, Marcus; Kovács, Sándor J; Borgquist, Rasmus; Revstedt, Johan; Söderlind, Gustaf; Arheden, Håkan; Heiberg, Einar

    2016-06-01

    To present and validate a new method for 4D flow quantification of vortex-ring mixing during early, rapid filling of the left ventricle (LV) as a potential index of diastolic dysfunction and heart failure. 4D flow mixing measurements were validated using planar laser-induced fluorescence (PLIF) in a phantom setup. Controls (n = 23) and heart failure patients (n = 23) were studied using 4D flow at 1.5T (26 subjects) or 3T (20 subjects) to determine vortex volume (VV) and inflowing volume (VVinflow ). The volume mixed into the vortex-ring was quantified as VVmix-in = VV-VVinflow . The mixing ratio was defined as MXR = VVmix-in /VV. Furthermore, we quantified the fraction of the end-systolic volume (ESV) mixed into the vortex-ring (VVmix-in /ESV) and the fraction of the LV volume at diastasis (DV) occupied by the vortex-ring (VV/DV). PLIF validation of MXR showed fair agreement (R(2) = 0.45, mean ± SD 1 ± 6%). MXR was higher in patients compared to controls (28 ± 11% vs. 16 ± 10%, P < 0.001), while VVmix-in /ESV and VV/DV were lower in patients (10 ± 6% vs. 18 ± 12%, P < 0.01 and 25 ± 8% vs. 50 ± 6%, P < 0.0001). Vortex-ring mixing can be quantified using 4D flow. The differences in mixing parameters observed between controls and patients motivate further investigation as indices of diastolic dysfunction. J. Magn. Reson. Imaging 2016;43:1386-1397. © 2015 Wiley Periodicals, Inc.

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

    SciTech Connect

    Ehler, E; Higgins, P; Dusenbery, K

    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.

  14. Microfluidics based phantoms of superficial vascular network

    PubMed Central

    Luu, Long; Roman, Patrick A.; Mathews, Scott A.; Ramella-Roman, Jessica C.

    2012-01-01

    Several new bio-photonic techniques aim to measure flow in the human vasculature non-destructively. Some of these tools, such as laser speckle imaging or Doppler optical coherence tomography, are now reaching the clinical stage. Therefore appropriate calibration and validation techniques dedicated to these particular measurements are therefore of paramount importance. In this paper we introduce a fast prototyping technique based on laser micromachining for the fabrication of dynamic flow phantoms. Micro-channels smaller than 20 µm in width can be formed in a variety of materials such as epoxies, plastics, and household tape. Vasculature geometries can be easily and quickly modified to accommodate a particular experimental scenario. PMID:22741081

  15. Professional Fulfillment and Satisfaction of US and Canadian Adult Education and Human Resource Development Faculty

    ERIC Educational Resources Information Center

    Peterson, Shari L.; Wiesenberg, Faye

    2004-01-01

    This comparative study explored the professional fulfillment and job satisfaction of US and Canadian college and university faculty in the fields of Adult Education and Human Resource Development. In Autumn 2001, we disseminated electronically "The Adult Education and Human Resource Development Faculty Survey" to a selected sample of Canadian and…

  16. Low abundances of synthetics lipids in phantoms

    NASA Astrophysics Data System (ADS)

    Villanueva-Luna, A. E.; Santiago-Alvarado, A.; Castro-Ramos, J.; Vazquez-Montiel, S.; Flores-Gil, A.; Aguilar-Soto, J.; Delgado-Atencio, J. A.

    2012-03-01

    Phantoms simulate optical characteristics of tissues. Phantoms use to mimic light distributions in living tissue. Several Phantoms compositions made of silicone, polyester, polyurethane, and epoxy resin have been described in the literature. These kinds of phantoms have the problem of long time preservation. In this work, we describe the fabrication and characterization of phantoms with low concentrations of synthetic lipid using Raman spectroscopy. We fabricate four phantoms made of Polydimethylsiloxane (PDMS). These phantoms have synthetic lipid content of cholesterol and triglycerides. The size of our phantoms is 1 x 1 cm and 5 mm of thickness.We used the point-to-point mapping technique. Finally, we compared advantages and performance of made PDMS and gelatin phantoms.

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

    SciTech Connect

    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.

    2014-03-15

    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

  18. A feasiblity study of an ultrasonic test phantom arm

    NASA Astrophysics Data System (ADS)

    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.

  19. Design of the optical phantom of tissue for photodynamic therapy research

    NASA Astrophysics Data System (ADS)

    Xie, Shusen; Profio, A. E.; Shu, Kuang-Hsien

    1993-03-01

    An optical phantom of tissue has been devised to simulate the optical properties of typical tissues for research in photodynamic therapy (PDT). The phantom consists of a scatterer (polystyrene-divinylbenzene microspheres) and an absorber (india ink) in distilled water. A set of relevant data for the microscopic optical properties and macroscopic optical parameter of the phantom was found. The results obtained approximate the optical properties of typical tissues. This optical phantom may duplicate the spatial variation of the radiant energy fluence of typical human tissues at 630 nm wavelength in PDT.

  20. Geometrically complex 3D-printed phantoms for diffuse optical imaging.

    PubMed

    Dempsey, Laura A; Persad, Melissa; Powell, Samuel; Chitnis, Danial; Hebden, Jeremy C

    2017-03-01

    Tissue-equivalent phantoms that mimic the optical properties of human and animal tissues are commonly used in diffuse optical imaging research to characterize instrumentation or evaluate an image reconstruction method. Although many recipes have been produced for generating solid phantoms with specified absorption and transport scattering coefficients at visible and near-infrared wavelengths, the construction methods are generally time-consuming and are unable to create complex geometries. We present a method of generating phantoms using a standard 3D printer. A simple recipe was devised which enables printed phantoms to be produced with precisely known optical properties. To illustrate the capability of the method, we describe the creation of an anatomically accurate, tissue-equivalent premature infant head optical phantom with a hollow brain space based on MRI atlas data. A diffuse optical image of the phantom is acquired when a high contrast target is inserted into the hollow space filled with an aqueous scattering solution.

  1. A teaching phantom for sonographers.

    PubMed

    Zagzebski, J A; Madsen, E L; Frank, G R

    1991-01-01

    An anthropomorphic torso section phantom is described that is intended for use during initial stages of ultrasonographer training. The phantom represents a section of the upper abdomen, with simulated ribs, liver, kidney with fat pad, gallbladder, aorta, and bowel gas. Positioned in the liver are ten simulated soft tissue masses, which produce a variety of typical echographic patterns. All simulated soft tissue components are formed of tissue-mimicking materials that match their corresponding tissue counterparts in terms of speed of sound, ultrasonic attenuation, and density. Construction details are presented and examples of images are shown.

  2. Features of hand-foot crawling behavior in human adults.

    PubMed

    Maclellan, M J; Ivanenko, Y P; Cappellini, G; Sylos Labini, F; Lacquaniti, F

    2012-01-01

    Interlimb coordination of crawling kinematics in humans shares features with other primates and nonprimate quadrupeds, and it has been suggested that this is due to a similar organization of the locomotor pattern generators (CPGs). To extend the previous findings and to further explore the neural control of bipedal vs. quadrupedal locomotion, we used a crawling paradigm in which healthy adults crawled on their hands and feet at different speeds and at different surface inclinations (13°, 27°, and 35°). Ground reaction forces, limb kinematics, and electromyographic (EMG) activity from 26 upper and lower limb muscles on the right side of the body were collected. The EMG activity was mapped onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools to characterize the general features of cervical and lumbosacral spinal cord activation. The spatiotemporal pattern of spinal cord activity significantly differed between quadrupedal and bipedal gaits. In addition, participants exhibited a large range of kinematic coordination styles (diagonal vs. lateral patterns), which is in contrast to the stereotypical kinematics of upright bipedal walking, suggesting flexible coupling of cervical and lumbosacral pattern generators. Results showed strikingly dissimilar directional horizontal forces for the arms and legs, considerably retracted average leg orientation, and substantially smaller sacral vs. lumbar motoneuron activity compared with quadrupedal gait in animals. A gradual transition to a more vertical body orientation (increasing the inclination of the treadmill) led to the appearance of more prominent sacral activity (related to activation of ankle plantar flexors), typical of bipedal walking. The findings highlight the reorganization and adaptation of CPG networks involved in the control of quadrupedal human locomotion and a high specialization of the musculoskeletal apparatus to specific gaits.

  3. High resolution, MRI-based, segmented, computerized head phantom

    SciTech Connect

    Zubal, I.G.; Harrell, C.R.; Smith, E.O.; Smith, A.L.; Krischlunas, P.

    1999-01-01

    The authors have created a high-resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. A software head phantom was created from 124 transverse MRI images of a healthy normal individual. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by the clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 byte array. Internal volumes compare favorably to those described in the ICRP Reference Man. The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer-based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient-specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, the high resolution, typical head geometry gives the most realistic patient model currently available.

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

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

    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

  5. Metric analysis of basal sphenoid angle in adult human skulls

    PubMed Central

    Netto, Dante Simionato; Nascimento, Sergio Ricardo Rios; Ruiz, Cristiane Regina

    2014-01-01

    Objective To analyze the variations in the angle basal sphenoid skulls of adult humans and their relationship to sex, age, ethnicity and cranial index. Methods The angles were measured in 160 skulls belonging to the Museum of the Universidade Federal de São Paulo Department of Morphology. We use two flexible rules and a goniometer, having as reference points for the first rule the posterior end of the ethmoidal crest and dorsum of the sella turcica, and for the second rule the anterior margin of the foramen magnum and clivus, measuring the angle at the intersection of two. Results The average angle was 115.41°, with no statistical correlation between the value of the angle and sex or age. A statistical correlation was noted between the value of the angle and ethnicity, and between the angle and the horizontal cranial index. Conclusions The distribution of the angle basal sphenoid was the same in sex, and there was correlation between the angle and ethnicity, being the proportion of non-white individuals with an angle >125° significantly higher than that of whites with an angle >125°. There was correlation between the angle and the cranial index, because skulls with higher cranial index tend to have higher basiesfenoidal angle too. PMID:25295452

  6. Spirituality of Adult Education and Training. Professional Practices in Adult Education and Human Resource Development Series.

    ERIC Educational Resources Information Center

    English, Leona M.; Fenwick, Tara J.; Parsons, Jim

    This book explores how spirituality intersects with the lives of adult educators and trainers. The following are among the topics discussed: (1) spirituality's role within the context of adult education and training and defining spirituality (the original spiritual purpose of adult education, as illustrated in the history of the Chautauqua,…

  7. Development and clinical application of a length-adjustable water phantom for total body irradiation.

    PubMed

    Chen, Zhi-Wei; Yao, Sheng-Yu; Zhang, Tie-Ning; Zhu, Zhen-Hua; Hu, Zhe-Kai; Lu, Xun

    2012-08-01

    A new type of water phantom which would be specialised for the absorbed dose measurement in total body irradiation (TBI) treatment is developed. Ten millimetres of thick Plexiglas plates were arranged to form a square cube with 300 mm of edge length. An appropriate sleeve-type piston was installed on the side wall, and a tabular Plexiglas piston was positioned inside the sleeve. By pushing and pulling the piston, the length of the self-made water phantom could be varied to meet the required patients' physical sizes. To compare the international standard water phantom with the length-adjustable and the Plexiglas phantoms, absorbed dose for 6-MV X ray was measured by an ionisation chamber at different depths in three kinds of phantoms. In 70 cases with TBI, midplane doses were metered using the length-adjustable and the Plexiglas phantoms for simulating human dimensions, and dose validation was synchronously carried out. There were no significant statistical differences, p > 0.05, through statistical processing of data from the international standard water phantom and the self-designed one. There were significant statistical differences, p < 0.05, between the two sets of data from the standard and the Plexiglas one. In addition, the absolute difference had a positive correlation with the varied depth of the detector in the Plexiglas phantom. Comparing the data of clinical treatment, the differences were all <1 % among the prescription doses and the validation data collected from the self-design water phantom. However, the differences collected from the Plexiglas phantom were increasing gradually from +0.77 to +2.30 % along with increasing body width. Obviously, the difference had a positive correlation with the body width. The results proved that the new length-adjustable water phantom is more accurate for simulating human dimensions than Plexiglas phantom.

  8. Epigallocatechin-3-gallate increases maximal oxygen uptake in adult humans.

    PubMed

    Richards, Jennifer C; Lonac, Mark C; Johnson, Tyler K; Schweder, Melani M; Bell, Christopher

    2010-04-01

    Epigallocatechin-3-gallate (EGCG), a component of green tea, increases endurance performance in animals and promotes fat oxidation during cycle ergometer exercise in adult humans. We have investigated the hypothesis that short-term consumption of EGCG delays the onset of the ventilatory threshold (VT) and increases maximal oxygen uptake (VO2max). In this randomized, repeated-measures, double-blind study, 19 healthy adults (11 males and 8 females, age = 26 ± 2 yr (mean ± SE)) received seven placebo or seven EGCG (135-mg) pills. Forty-eight hours before data collection, participants began consuming three pills per day; the last pill was taken 2 h before exercise testing. VT and VO2max were determined from breath-by-breath indirect calorimetry data collected during continuous incremental stationary cycle ergometer exercise (20-35 W·min(-1)), from rest until volitional fatigue. Each condition/exercise test was separated by a minimum of 14 d. Compared with placebo, short-term EGCG consumption increased VO2max (3.123 ± 0.187 vs 3.259 ± 0.196 L·min(-1), P = 0.04). Maximal work rate (301 ± 15 vs 301 ± 16 W, P = 0.98), maximal RER (1.21 ± 0.01 vs 1.22 ± 0.02, P = 0.27), and maximal HR were unaffected (180 ± 3 vs 180 ± 3 beats·min(-1), P = 0.87). In a subset of subjects (n = 11), maximal cardiac output (determined via open-circuit acetylene breathing) was also unaffected by EGCG (29.6 ± 2.2 vs 30.2 ± 1.4 L·min(-1), P = 0.70). Contrary to our hypothesis, EGCG decreased VO2 at VT (1.57 ± 0.11 vs 1.48 ± 0.10 L·min(-1)), but this change was not significant (P = 0.06). Short-term consumption of EGCG increased VO2max without affecting maximal cardiac output, suggesting that EGCG may increase arterial-venous oxygen difference.

  9. An anatomically realistic brain phantom for quantification with positron tomography

    SciTech Connect

    Wong, D.F.; Links, J.M.; Molliver, M.E.; Hengst, T.C.; Clifford, C.M.; Buhle, L.; Bryan, M.; Stumpf, M.; Wagner, H.N. Jr.

    1984-01-01

    Phantom studies are useful in assessing and maximizing the accuracy and precision of quantification of absolute activity, assessing errors associated with patient positioning, and dosimetry. Most phantoms are limited by the use of simple shapes, which do not adequately reflect real anatomy. The authors have constructed an anatomically realistic life-size brain phantom for positron tomography studies. The phantom consists of separately fillable R + L caudates, R + L putamens, R + L globus passidus and cerebellum. These structures are contained in proper anatomic orientation within a fillable cerebrum. Solid ventricles are also present. The entire clear vinyl cerebrum is placed in a human skull. The internal brain structures were fabricated from polyester resin, with dimensions, shapes and sizes of the structures obtained from digitized contours of brain slices in the U.C.S.D. computerized brain atlas. The structures were filled with known concentrations of Ga-68 in water and scanned with our NeuroECAT. The phantom was aligned in the scanner for each structure, such that the tomographic slice passed through that structure's center. After calibration of the scanner with a standard phantom for counts/pixel uCi/cc conversion, the measured activity concentrations were compared with the actual concentrations. The ratio of measured to actual activity concentration (''recovery coefficient'') for the caudate was 0.33; for the putamen 0.42. For comparison, the ratio for spheres of diameters 9.5, 16,19 and 25.4 mm was 0.23, 0.54, 0.81, and 0.93. This phantom provides more realistic assessment of performance and allows calculation of correction factors.

  10. Biomedical Tissue Phantoms with Controlled Geometric and Optical Properties for Raman Spectroscopy and Tomography

    PubMed Central

    Esmonde-White, Francis W.L.; Esmonde-White, Karen A.; Kole, Matthew R.; Goldstein, Steven A.; Roessler, Blake J.; Morris, Michael D.

    2012-01-01

    To support the translation of Raman spectroscopy into clinical applications, synthetic models are needed to accurately test, optimize and validate prototype fiber optic instrumentation. Synthetic models (also called tissue phantoms) are widely used for developing and testing optical instrumentation for diffuse reflectance, fluorescence, and Raman spectroscopies. While existing tissue phantoms accurately model tissue optical scattering and absorption, they do not typically model the anatomic shapes and chemical composition of tissue. Because Raman spectroscopy is sensitive to molecular composition, Raman tissue phantoms should also approximate the bulk tissue composition. We describe the fabrication and characterization of tissue phantoms for Raman tomography and spectroscopy. These phantoms have controlled chemical and optical properties, and also multilayer morphologies which approximate the appropriate anatomic shapes. Tissue phantoms were fabricated to support on-going Raman studies by simulating human wrist and rat leg. Surface meshes (triangle patch models) were generated from computed tomography (CT) images of a human arm and rat leg. Rapid prototyping was used to print mold templates with complex geometric patterns. Plastic casting techniques used for movie special effects were adapted to fabricate molds from the rapid prototypes, and finally to cast multilayer gelatin tissue phantoms. The gelatin base was enriched with additives to model the approximate chemistry and optical properties of individual tissue layers. Additional studies were performed to determine optimal casting conditions, phantom stability, layer delamination and chemical diffusion between layers. Recovery of diffuse reflectance and Raman spectra in tissue phantoms varied with probe placement. These phantoms enable optimization of probe placement for human or rat studies. These multilayer tissue phantoms with complex geometries are shown to be stable, with minimal layer delamination and

  11. 21 CFR 892.1420 - Radionuclide test pattern phantom.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radionuclide test pattern phantom. 892.1420 Section 892.1420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1420 Radionuclide test pattern...

  12. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  13. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  14. 21 CFR 892.1420 - Radionuclide test pattern phantom.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radionuclide test pattern phantom. 892.1420 Section 892.1420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1420 Radionuclide test pattern...

  15. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  16. 21 CFR 892.1420 - Radionuclide test pattern phantom.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radionuclide test pattern phantom. 892.1420 Section 892.1420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1420 Radionuclide test pattern...

  17. 21 CFR 892.1420 - Radionuclide test pattern phantom.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radionuclide test pattern phantom. 892.1420 Section 892.1420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1420 Radionuclide test pattern...

  18. 21 CFR 892.1420 - Radionuclide test pattern phantom.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radionuclide test pattern phantom. 892.1420 Section 892.1420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1420 Radionuclide test pattern...

  19. Transcriptional profiling of adult neural stem-like cells from the human brain.

    PubMed

    Sandberg, Cecilie Jonsgar; Vik-Mo, Einar O; Behnan, Jinan; Helseth, Eirik; Langmoen, Iver A

    2014-01-01

    There is a great potential for the development of new cell replacement strategies based on adult human neural stem-like cells. However, little is known about the hierarchy of cells and the unique molecular properties of stem- and progenitor cells of the nervous system. Stem cells from the adult human brain can be propagated and expanded in vitro as free floating neurospheres that are capable of self-renewal and differentiation into all three cell types of the central nervous system. Here we report the first global gene expression study of adult human neural stem-like cells originating from five human subventricular zone biopsies (mean age 42, range 33-60). Compared to adult human brain tissue, we identified 1,189 genes that were significantly up- and down-regulated in adult human neural stem-like cells (1% false discovery rate). We found that adult human neural stem-like cells express stem cell markers and have reduced levels of markers that are typical of the mature cells in the nervous system. We report that the genes being highly expressed in adult human neural stem-like cells are associated with developmental processes and the extracellular region of the cell. The calcium signaling pathway and neuroactive ligand-receptor interactions are enriched among the most differentially regulated genes between adult human neural stem-like cells and adult human brain tissue. We confirmed the expression of 10 of the most up-regulated genes in adult human neural stem-like cells in an additional sample set that included adult human neural stem-like cells (n = 6), foetal human neural stem cells (n = 1) and human brain tissues (n = 12). The NGFR, SLITRK6 and KCNS3 receptors were further investigated by immunofluorescence and shown to be heterogeneously expressed in spheres. These receptors could potentially serve as new markers for the identification and characterisation of neural stem- and progenitor cells or as targets for manipulation of cellular fate.

  20. Hyperoxia Induces Inflammation and Cytotoxicity in Human Adult Cardiac Myocytes.

    PubMed

    Hafner, Christina; Wu, Jing; Tiboldi, Akos; Hess, Moritz; Mitulovic, Goran; Kaun, Christoph; Krychtiuk, Konstantin Alexander; Wojta, Johann; Ullrich, Roman; Tretter, Eva Verena; Markstaller, Klaus; Klein, Klaus Ulrich

    2017-04-01

    Supplemental oxygen (O2) is used as adjunct therapy in anesthesia, emergency, and intensive care medicine. We hypothesized that excessive O2 levels (hyperoxia) can directly injure human adult cardiac myocytes (HACMs). HACMs obtained from the explanted hearts of transplantation patients were exposed to constant hyperoxia (95% O2), intermittent hyperoxia (alternating 10 min exposures to 5% and 95% O2), constant normoxia (21% O2), or constant mild hypoxia (5% O2) using a bioreactor. Changes in cell morphology, viability as assessed by lactate dehydrogenase (LDH) release and trypan blue (TB) staining, and secretion of vascular endothelial growth factor (VEGF), macrophage migration inhibitory factor (MIF), and various pro-inflammatory cytokines (interleukin, IL; chemokine C-X-C motif ligand, CXC; granulocyte-colony stimulating factor, G-CSF; intercellular adhesion molecule, ICAM; chemokine C-C motif ligand, CCL) were compared among treatment groups at baseline (0 h) and after 8, 24, and 72 h of treatment. Changes in HACM protein expression were determined by quantitative proteomic analysis after 48 h of exposure. Compared with constant normoxia and mild hypoxia, constant hyperoxia resulted in a higher TB-positive cell count, greater release of LDH, and elevated secretion of VEGF, MIF, IL-1β, IL-6, IL-8, CXCL-1, CXCL-10, G-CSF, ICAM-1, CCL-3, and CCL-5. Cellular inflammation and cytotoxicity gradually increased and was highest after 72 h of constant and intermittent hyperoxia. Quantitative proteomic analysis revealed that hypoxic and hyperoxic O2 exposure differently altered the expression levels of proteins involved in cell-cycle regulation, energy metabolism, and cell signaling. In conclusion, constant and intermittent hyperoxia induced inflammation and cytotoxicity in HACMs. Cell injury occurred earliest and was greatest after constant hyperoxia, but even relatively brief repeating hyperoxic episodes induced a substantial inflammatory response.

  1. Anisotropic microstructured poly(vinyl alcohol) tissue-mimicking phantoms.

    PubMed

    Dawson, Andrew; Harris, Paul; Gouws, Gideon

    2010-07-01

    Novel microstructured PVA phantoms mimicking fibrous tissues have been developed using a simple freeze-casting process. Scanning electron micrographs reveal highly anisotropic microstructure with dimensions of the order of 5 to 100 microm. Characterization of an example phantom revealed acoustic properties consistent with those found in fibrous tissues. At 20 MHz, the velocity measured parallel to the microstructure orientation of 1555 ms(-1) was significantly greater than that perpendicular to the microstructure of 1537 ms(-1). The attenuation coefficient was measured to be 5 dBxmm(-1) and proportional to the 1.6 power of frequency, which is in good agreement with that for normal human myocardium.

  2. Phantom limb pain and related disorders.

    PubMed

    Weinstein, S M

    1998-11-01

    Postamputation phenomena, including painful and nonpainful phantom sensations occur following loss of limbs and other body parts. Peripheral and central nervous system mechanisms play a role in persistent phantom pain. Understanding the pathophysiology of this syndrome has improved in recent years. Comprehensive evaluation and a multimodality treatment approach comprise the current standard of care of the patient with phantom pain.

  3. Phantom Recollection of Bridging and Elaborative Inferences

    ERIC Educational Resources Information Center

    Singer, Murray; Spear, Jackie

    2015-01-01

    The phantom recollection model is a multiprocess analysis according to which memory judgments are collaboratively supported by one's recollection of an item in its context, a vaguer sense of stimulus familiarity, and the phantom recollection of the substance and even perceptual details of unstudied but related lures. Phantom recollection has…

  4. Adult Education and the Human Environment: Transactions of a Celebration.

    ERIC Educational Resources Information Center

    Jones-Quartey, K. A. B., Ed.; And Others

    The document comprises a collection of speeches and seminar reports arising from the 25th anniversary celebration of the Institute of Adult Education at the University of Ghana. The theme of the celebration, introduced in the first chapter, was Adult Education and Man's Environment--the Next Quarter-Century. The second chapter comprises the…

  5. Phantom Torso in HRF section of Destiny module

    NASA Image and Video Library

    2001-05-02

    ISS002-E-6080 (2 May 2001) --- The Phantom Torso, seen here in the Human Research Facility (HRF) section of the Destiny/U.S. laboratory on the International Space Station (ISS), is designed to measure the effects of radiation on organs inside the body by using a torso that is similar to those used to train radiologists on Earth. The torso is equivalent in height and weight to an average adult male. It contains radiation detectors that will measure, in real-time, how much radiation the brain, thyroid, stomach, colon, and heart and lung area receive on a daily basis. The data will be used to determine how the body reacts to and shields its internal organs from radiation, which will be important for longer duration space flights. The experiment was delivered to the orbiting outpost during by the STS-100/6A crew in April 2001. Dr. Gautam Badhwar, NASA JSC, Houston, TX, is the principal investigator for this experiment. A digital still camera was used to record this image.

  6. Organ dose conversion coefficients for pediatric reference computational phantoms in external photon radiation fields

    NASA Astrophysics Data System (ADS)

    Chang, Lienard A.

    In the event of a radiological accident or attack, it is important to estimate the organ doses to those exposed. In general, it is difficult to measure organ dose directly in the field and therefore dose conversion coefficients (DCC) are needed to convert measurable values such as air kerma to organ dose. Previous work on these coefficients has been conducted mainly for adults with a focus on radiation protection workers. Hence, there is a large gap in the literature for pediatric values. This study coupled a Monte Carlo N-Particle eXtended (MCNPX) code with International Council of Radiological Protection (ICRP)-adopted University of Florida and National Cancer Institute pediatric reference phantoms to calculate a comprehensive list of dose conversion coefficients (mGy/mGy) to convert air-kerma to organ dose. Parameters included ten phantoms (newborn, 1-year, 5-year, 10-year, 15-year old male and female), 28 organs over 33 energies between 0.01 and 20 MeV in six (6) irradiation geometries relevant to a child who might be exposed to a radiological release: anterior-posterior (AP), posterior-anterior (PA), right-lateral (RLAT), left-lateral (LLAT), rotational (ROT), and isotropic (ISO). Dose conversion coefficients to the red bone marrow over 36 skeletal sites were also calculated. It was hypothesized that the pediatric organ dose conversion coefficients would follow similar trends to the published adult values as dictated by human anatomy, but be of a higher magnitude. It was found that while the pediatric coefficients did yield similar patterns to that of the adult coefficients, depending on the organ and irradiation geometry, the pediatric values could be lower or higher than that of the adult coefficients.

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

    PubMed

    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.

  8. Small Rodent Cardiac Phantom for Preclinical Ultrasound Imaging.

    PubMed

    Anderson, Tom

    2017-01-01

    Imaging phantoms play a valuable role in the quality control and quality assurance of medical imaging systems. However, for use in the relatively new field of small-animal preclinical imaging, very few have been described in the literature, and even less or none at all are available commercially. Yet, preclinical small animal phantoms offer the possibility of reducing the need for live animals for test and measurement purposes. Human scale cardiac phantoms, both reported in the literature and available commercially, are typically complex devices. Their designs include numerous flow control valves, pumps, and servo motors. These devices are coupled to tissue mimicking materials (TMMs) shaped to replicate the form of cardiac chambers and valves. They are then operated in such a way as to cause the replica TMM heart to move in a lifelike manner. This paper describes the design and construction of a small rodent preclinical cardiac phantom, which is both of a simple design and construction. Using only readily available materials and components, it can be manufactured without the use of workshop facilities, using only hand-tools. Drawings and pictures of the design are presented along with images of the phantom in operation, using a high-frequency preclinical ultrasound scanner.

  9. A multimodal (MRI/ultrasound) cardiac phantom for imaging experiments

    NASA Astrophysics Data System (ADS)

    Tavakoli, Vahid; Kendrick, Michael; Shakeri, Mostafa; Alshaher, Motaz; Stoddard, Marcus F.; Amini, Amir

    2013-03-01

    A dynamic cardiac phantom can play a significant role in the evaluation and development of ultrasound and cardiac magnetic resonance (MR) motion tracking and registration methods. A four chamber multimodal cardiac phantom has been designed and built to simulate normal and pathologic hearts with different degrees of "infarction" and "scar tissues". In this set up, cardiac valves have been designed and modeled as well. The four-chamber structure can simulate the asymmetric ventricular, atrial and valve motions. Poly Vinyl Alcohol (PVA) is used as the principal material since it can simulate the shape, elasticity, and MR and ultrasound properties of the heart. The cardiac shape is simulated using a four-chamber mold made of polymer clay. An additional pathologic heart phantom containing stiff inclusions has been manufactured in order to simulate an infracted heart. The stiff inclusions are of different shapes and different degrees of elasticity and are able to simulate abnormal cardiac segments. The cardiac elasticity is adjusted based on freeze-thaw cycles of the PVA cryogel for normal and scarred regions. Ultrasound and MRI markers were inserted in the cardiac phantom as landmarks for validations. To the best of our knowledge, this is the first multimodal phantom that models a dynamic four-chamber human heart including the cardiac valve.

  10. Full scattering profile of circular optical phantoms mimicking biological tissue

    NASA Astrophysics Data System (ADS)

    Feder, Idit; Wróbel, Maciej S.; Duadi, Hamootal; Fixler, Dror; Jedrzejewska-Szczerska, Malgorzata

    2017-02-01

    Human tissue is one of the most complex optical media since it is turbid and nonhomogeneous. In our poster, we suggest a new type of skin phantom and an optical method for sensing physiological tissue condition, basing on the collection of the ejected light at all exit angles, to receive the full scattering profile. Conducted experiments were carried out on an unique set-up for noninvasive encircled measurement. Set-up consisted of a laser, a photodetector and new tissues-like phantoms made with a polyvinyl chloride-plastisol (PVCP), silicone elastomer polydimethylsiloxane (PDMS) and PDMS with glycerol mixture. Our method reveals an isobaric point, which is independent of the optical properties. Furthermore, we present the angular distribution of cylindrical phantoms, in order to sense physiological tissue state.

  11. Dose distributions in a human head phantom for neutron capture therapy using moderated neutrons from the 2.5 meV proton-7Li reaction or from fission of 235U.

    PubMed

    Tanaka, K; Kobayashi, T; Sakurai, Y; Nakagawa, Y; Endo, S; Hoshi, M

    2001-10-01

    The feasibility of neutron capture therapy (NCT) using an accelerator-based neutron source of the 7Li(p,n) reaction produced by 2.5 MeV protons was investigated by comparing the neutron beam tailored by both the Hiroshima University radiological research accelerator (HIRRAC) and the heavy water neutron irradiation facility in the Kyoto University reactor (KUR-HWNIF) from the viewpoint of the contamination dose ratios of the fast neutrons and the gamma rays. These contamination ratios to the boron dose were estimated in a water phantom of 20 cm diameter and 20 cm length to simulate a human head, with experiments by the same techniques for NCT in KUR-HWNIF and/or the simulation calculations by the Monte Carlo N-particle transport code system version 4B (MCNP-4B). It was found that the 7Li(p,n) neutrons produced by 2.5 MeV protons combined with 20, 25 or 30 cm thick D20 moderators of 20 cm diameter could make irradiation fields for NCT with depth-dose characteristics similar to those from the epithermal neutron beam at the KUR-HWNIF.

  12. Development of an effective dose coefficient database using a computational human phantom and Monte Carlo simulations to evaluate exposure dose for the usage of NORM-added consumer products.

    PubMed

    Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Jaekook; Yeom, Yeon Soo; Kim, Chan Hyeong; Chang, Byung-Uck; Min, Chul Hee

    2017-11-01

    After the Fukushima accident in Japan, the Korean Government implemented the "Act on Protective Action Guidelines Against Radiation in the Natural Environment" to regulate unnecessary radiation exposure to the public. However, despite the law which came into effect in July 2012, an appropriate method to evaluate the equivalent and effective doses from naturally occurring radioactive material (NORM) in consumer products is not available. The aim of the present study is to develop and validate an effective dose coefficient database enabling the simple and correct evaluation of the effective dose due to the usage of NORM-added consumer products. To construct the database, we used a skin source method with a computational human phantom and Monte Carlo (MC) simulation. For the validation, the effective dose was compared between the database using interpolation method and the original MC method. Our result showed a similar equivalent dose across the 26 organs and a corresponding average dose between the database and the MC calculations of < 5% difference. The differences in the effective doses were even less, and the result generally show that equivalent and effective doses can be quickly calculated with the database with sufficient accuracy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Cone-beam CT versus multi-slice CT systems for postoperative imaging of cochlear implantation--a phantom study on image quality and radiation exposure using human temporal bones.

    PubMed

    Theunisse, Henricus J; Joemai, Raoul M S; Maal, Thomas J J; Geleijns, Jacob; Mylanus, Emmanuel A M; Verbist, Berit M

    2015-04-01

    Image quality of low-dose multi-slice computed tomography (MSCT) after cochlear implantation is comparable to that of cone-beam computed tomography (CBCT). CBCT has been described as a low-dose alternative with superior image quality to MSCT for postoperative cochlear implant (CI) imaging, but to our knowledge, no dose-matched comparisons of image quality have been published. Five human cochleae were implanted with CI electrodes and scanned on two CBCT and two MSCT systems. Four independent observers rated aspects of image quality on a five-point scale. CBCT scans were compared to clinical and dose-matched MSCT scans. Declining-dose MSCT protocols were compared to the clinical protocol. CT phantoms were used to determine effective dose and resolution for each acquisition protocol. Effective dose of the CBCT protocols was 6 to 16% of the clinical MSCT dose. Visibility of cochlear inner and outer walls and overall image quality were positively correlated with radiation dose on MSCT and image quality was better with clinical MSCT than with CBCT protocols. In other comparisons, differences between systems were found, but a distinction between CBCT and MSCT could not be made. CBCT and dose-matched MSCT are both suitable for postoperative CI imaging. Selecting a CT system and radiation dose depends on which cochlear structures need to be visualized.

  14. Effect of Anatomical Modeling on Space Radiation Dose Estimates: A Comparison of Doses for NASA Phantoms and 5th, 50th, and 95th Percentile UF Hybrid Phantoms

    NASA Technical Reports Server (NTRS)

    Bahadori, A.; VanBaalen, M.; Shavers, M.; Semones, E.; Dodge, C.; Bolch, W.

    2010-01-01

    The estimate of absorbed dose to individual organs of a space crewmember is affected by the geometry of the anatomical model of the astronaut used in the radiation transport calculation. For astronaut dosimetry, NASA currently uses the computerized anatomical male (CAM) and computerized anatomical female (CAF) stylized phantoms to represent astronauts in its operational radiation dose analyses. These phantoms are available in one size and in two body positions. In contrast, the UF Hybrid Adult Male and Female (UFHADM and UFHADF) phantoms have organ shapes based on actual CT data. The surfaces of these phantoms are defined by non-uniform rational B-spline surfaces, and are thus flexible in terms of body morphometry and extremity positioning. In this study, UFHADM and UFHADF are scaled to dimensions corresponding to 5th, 50th, and 95th percentile (PCTL) male and female astronauts. A ray-tracing program is written in Visual Basic 2008, which is then used to create areal density maps for dose points corresponding to various organs within the phantoms. The areal density maps, along with appropriate space radiation spectra, are input into the NASA program couplet HZETRN/BRYNTRN, and organ doses are calculated. The areal density maps selected tissues and organs of the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared. In addition, the organ doses for the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared to organ doses for CAM and CAF.

  15. Effect of Anatomical Modeling on Space Radiation Dose Estimates: A Comparison of Doses for NASA Phantoms and 5th, 50th, and 95th Percentile UF Hybrid Phantoms

    NASA Technical Reports Server (NTRS)

    Bahadori, A.; VanBaalen, M.; Shavers, M.; Semones, E.; Dodge, C.; Bolch, W.

    2010-01-01

    The estimate of absorbed dose to individual organs of a space crewmember is affected by the geometry of the anatomical model of the astronaut used in the radiation transport calculation. For astronaut dosimetry, NASA currently uses the computerized anatomical male (CAM) and computerized anatomical female (CAF) stylized phantoms to represent astronauts in its operational radiation dose analyses. These phantoms are available in one size and in two body positions. In contrast, the UF Hybrid Adult Male and Female (UFHADM and UFHADF) phantoms have organ shapes based on actual CT data. The surfaces of these phantoms are defined by non-uniform rational B-spline surfaces, and are thus flexible in terms of body morphometry and extremity positioning. In this study, UFHADM and UFHADF are scaled to dimensions corresponding to 5th, 50th, and 95th percentile (PCTL) male and female astronauts. A ray-tracing program is written in Visual Basic 2008, which is then used to create areal density maps for dose points corresponding to various organs within the phantoms. The areal density maps, along with appropriate space radiation spectra, are input into the NASA program couplet HZETRN/BRYNTRN, and organ doses are calculated. The areal density maps selected tissues and organs of the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared. In addition, the organ doses for the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared to organ doses for CAM and CAF.

  16. Brain stem auditory evoked responses in human infants and adults

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Galambos, R.

    1974-01-01

    Brain stem evoked potentials were recorded by conventional scalp electrodes in infants (3 weeks to 3 years of age) and adults. The latency of one of the major response components (wave V) is shown to be a function both of click intensity and the age of the subject; this latency at a given signal strength shortens postnatally to reach the adult value (about 6 msec) by 12 to 18 months of age. The demonstrated reliability and limited variability of these brain stem electrophysiological responses provide the basis for an optimistic estimate of their usefulness as an objective method for assessing hearing in infants and adults.

  17. Brain stem auditory evoked responses in human infants and adults

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Galambos, R.

    1974-01-01

    Brain stem evoked potentials were recorded by conventional scalp electrodes in infants (3 weeks to 3 years of age) and adults. The latency of one of the major response components (wave V) is shown to be a function both of click intensity and the age of the subject; this latency at a given signal strength shortens postnatally to reach the adult value (about 6 msec) by 12 to 18 months of age. The demonstrated reliability and limited variability of these brain stem electrophysiological responses provide the basis for an optimistic estimate of their usefulness as an objective method for assessing hearing in infants and adults.

  18. Comparison of monoenergetic photon organ dose rate coefficients for stylized and voxel phantoms submerged in air

    SciTech Connect

    Bellamy, Michael B.; Hiller, Mauritius M.; Dewji, Shaheen A.; Veinot, Kenneth G.; Leggett, Richard Wayne; Eckerman, Keith F.; Easterly, Clay E.; Hertel, Nolan E.

    2016-02-01

    As part of a broader effort to calculate effective dose rate coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, soil or water, age-specific stylized phantoms have been employed to determine dose coefficients relating dose rate to organs and tissues in the body. In this article, dose rate coefficients computed using the International Commission on Radiological Protection reference adult male voxel phantom are compared with values computed using the Oak Ridge National Laboratory adult male stylized phantom in an air submersion exposure geometry. Monte Carlo calculations for both phantoms were performed for monoenergetic source photons in the range of 30 keV to 5 MeV. Furthermore, these calculations largely result in differences under 10 % for photon energies above 50 keV, and it can be expected that both models show comparable results for the environmental sources of radionuclides.

  19. Comparison of monoenergetic photon organ dose rate coefficients for stylized and voxel phantoms submerged in air

    DOE PAGES

    Bellamy, Michael B.; Hiller, Mauritius M.; Dewji, Shaheen A.; ...

    2016-02-01

    As part of a broader effort to calculate effective dose rate coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, soil or water, age-specific stylized phantoms have been employed to determine dose coefficients relating dose rate to organs and tissues in the body. In this article, dose rate coefficients computed using the International Commission on Radiological Protection reference adult male voxel phantom are compared with values computed using the Oak Ridge National Laboratory adult male stylized phantom in an air submersion exposure geometry. Monte Carlo calculations for both phantoms were performed for monoenergetic source photonsmore » in the range of 30 keV to 5 MeV. Furthermore, these calculations largely result in differences under 10 % for photon energies above 50 keV, and it can be expected that both models show comparable results for the environmental sources of radionuclides.« less

  20. Characterization and evaluation of tissue-mimicking gelatin phantoms for use with MRgFUS.

    PubMed

    Farrer, Alexis I; Odéen, Henrik; de Bever, Joshua; Coats, Brittany; Parker, Dennis L; Payne, Allison; Christensen, Douglas A

    2015-01-01

    A tissue-mimicking phantom that accurately represents human-tissue properties is important for safety testing and for validating new imaging techniques. To achieve a variety of desired human-tissue properties, we have fabricated and tested several variations of gelatin phantoms. These phantoms are simple to manufacture and have properties in the same order of magnitude as those of soft tissues. This is important for quality-assurance verification as well as validation of magnetic resonance-guided focused ultrasound (MRgFUS) treatment techniques. The phantoms presented in this work were constructed from gelatin powders with three different bloom values (125, 175, and 250), each one allowing for a different mechanical stiffness of the phantom. Evaporated milk was used to replace half of the water in the recipe for the gelatin phantoms in order to achieve attenuation and speed of sound values in soft tissue ranges. These acoustic properties, along with MR (T1 and T2*), mechanical (density and Young's modulus), and thermal properties (thermal diffusivity and specific heat capacity), were obtained through independent measurements for all three bloom types to characterize the gelatin phantoms. Thermal repeatability of the phantoms was also assessed using MRgFUS and MR thermometry. All the measured values fell within the literature-reported ranges of soft tissues. In heating tests using low-power (6.6 W) sonications, interleaved with high-power (up to 22.0 W) sonications, each of the three different bloom phantoms demonstrated repeatable temperature increases (10.4 ± 0.3 °C for 125-bloom, 10.2 ± 0.3 °C for 175-bloom, and 10.8 ± 0.2 °C for 250-bloom for all 6.6-W sonications) for heating durations of 18.1 s. These evaporated milk-modified gelatin phantoms should serve as reliable, general soft tissue-mimicking MRgFUS phantoms.

  1. Adult Continuing Education and Human Resource Development: Present Competitors, Potential Partners

    ERIC Educational Resources Information Center

    Smith, Douglas H.

    2006-01-01

    Adult Continuing Education (ACE) and Human Resource Development (HRD) have grown tremendously in the last quarter century. ACE experienced tremendous growth in the 60s and 70s, with over 17 million attending colleges and universities, and local school and community adult education programs by the end of the 1970s. More ACE programs were started…

  2. Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

    PubMed Central

    Ramachandran, V. S.

    1993-01-01

    Recent behavioral and physiological evidence suggests that even brief sensory deprivation can lead to the rapid emergence of new and functionally effective neural connections in the adult human brain. Images Fig. 2 PMID:8248123

  3. Phantom limb syndrome: a review.

    PubMed

    Chahine, Lama; Kanazi, Ghassan

    2007-06-01

    Phantom limb syndrome is a condition in which patients experience sensations, whether painful or otherwise, in a limb that does not exist. It has been reported to occur in 80-100% of amputees, and typically has a chronic course, often resistant to treatment. Risk factors include the presence of preoperative pain, traumatic amputation, and the type of anesthetic procedure used during amputation. Several pathophysiologic theories have been proposed, including spinal mechanisms, central sensitization, and somatosensory cortical rearrangements, and while recent studies have shed light on some interesting and significant data, a lot remains to be understood. Treatments include pharmacologic, mechanical, and behavioral modalities, but substantial efficacy in well-designed, randomized controlled trials has yet to be demonstrated. Phantom limb syndrome continues to be a difficult condition to both understand and treat.

  4. Imaging CDMAM phantom with tomosynthesis

    NASA Astrophysics Data System (ADS)

    Ren, Baorui; Smith, Andy; Ruth, Chris; Jing, Zhenxue

    2008-03-01

    We studied the use of the mammography contrast detail phantom (CDMAM) with tomosynthesis to evaluate the performance of our system as well as to explore the application of CDMAM in 3D breast imaging. The system was Hologic's 1st generation tomosynthesis machine. CDMAM phantom plus PMMA slabs were imaged at 3 cm, 5 cm, 7 cm, and 9 cm PMMA-equivalent thickness with 11 projections per scan and the scan angle selected from 0, 15 and 28 degrees. CDMAM images were reconstructed using the back projection method, and were scored with the CDCOM automatic analysis program. The threshold thickness of each disk size was obtained with psychometric curve fitting. We first studied errors and variability associated with the results when different numbers of images were used in contrast detail analysis, then studied factors that affected CDMAM results in tomosynthesis, including the x-ray dose, the scan angle, the in-plane reconstruction pixel size, the slice-to-slice step size, the location of the CDMAM inside the PMMA slabs, and the scatter effect. This paper will present results of CDMAM performance of our tomosynthesis system, as well as their dependence on the various factors, and the comparison with 2D mammography. Additionally we will discuss the novel processing and analysis methods developed during this study, and make proposals to modify the CDMAM phantom and the CDCOM analysis program to optimize the method for 3D tomosynthesis.

  5. Newborn human skin fibroblasts senesce in vitro without acquiring adult growth factor requirements

    SciTech Connect

    Wharton, W.

    1984-01-01

    Cultures of human fibroblasts were prepared from chest skin obtained either from newborns (less than 3 months old) or adults (more than 35 years old) and maintained in vitro until they senesced. Adult cells grew logarithmically in medium supplemented with whole blood serum but not with platelet-poor plasma. Early passage cells obtained from newborns grew equally well in either plasma- or serum-supplemented medium. The difference in growth factor requirements between adult and newborn cells persisted through the lifespan of the cells; i.e., newborn cells did not develop adult hormonal requirements when maintained in culture. Thus, in vitro cellular aging can be distinguished from some types of differentiation.

  6. A simple phantom for learning EUS-guided FNA.

    PubMed

    Sorbi, Darius; Vazquez-Sequeiros, Enrique; Wiersema, Maurits J

    2003-04-01

    The learning curve for EUS-guided FNA (EUS-FNA) is formidable. Development of a phantom to assist in teaching the technique may be beneficial. This study assessed the feasibility of using a low-cost phantom made of commonly available materials to practice EUS-FNA. A 2500-mL barium enema bag was modified by running a plastic tube (3-mm inner diameter) through it and sealing one end. One hundred grams of standard agar were suspended in 4 liters of tap water. The broth was heated slowly to boiling. The dissolved agar was then transferred to the barium enema bag after mixing in diced carrots, elbow macaroni, peas, and fingertips of surgical gloves filled with 5 mL of normal saline solution (6 of each) to simulate solid and cystic lesions. Immersion of the phantom in a basin of water provided acoustic coupling. One end of the 3-mm plastic tubing was attached to the nozzle of a water jet device and the other end to its reservoir to create a closed system allowing water recirculation. A linear array echoendoscope and a fine needle were used to perform EUS-FNA. The analysis is descriptive. The phantom was readily made with inexpensive components (total cost <$50). With refrigeration the phantom was used repetitively during a 4-month period. It produced EUS images with an echotexture comparable with liver. The solid and cystic components resembled hepatic cysts and solid masses encountered when performing EUS in humans. Under EUS-guidance, fine-needle aspirates of selected lesions could be performed allowing targeting, aspiration, and sampling of selected lesions. The Doppler flow effect allowed examination of a simulated vascular structure during FNA. Once validated, an EUS phantom made of simple components may become an invaluable educational tool for teaching EUS-FNA. Further studies are needed to determine how it affects the skills of gastroenterologists with and without EUS experience.

  7. Phantom limb after stroke: an underreported phenomenon.

    PubMed

    Antoniello, Daniel; Kluger, Benzi M; Sahlein, Daniel H; Heilman, Kenneth M

    2010-10-01

    The presence of a phantom limb (PL) resulting from a cerebral lesion has been reported to be a rare event. No prior study, however, has systematically investigated the prevalence of this syndrome in a group of post-stroke individuals. Fifty post-stroke individuals were examined with structured interview/questionnaire to establish the presence and perceptual characteristics of PLs. We document the presence of phantom experiences in over half of these individuals (n=27). We provide details of these phantom experiences and further characterize these symptoms in terms of temporal qualities, posture, kinesthesia, and associated features. Twenty-two participants reported postural phantoms, which were perceived as illusions of limb position that commonly manifested while lying in bed at night - a time when visual input is removed from multi-sensory integration. Fourteen participants reported kinesthetic phantoms, with illusory movements ranging from simple single joint sensations to complex goal-directed phantom movements. A striking syndrome of near total volitional control of phantom movements was reported in four participants who had immobile plegic hands. Reduplicative phantom percepts were reported by only one participant. Similarly, phantom pain was present in only one individual - the sole participant with a pre-stroke limb amputation. The results suggest that stroke results in phantom experiences more commonly than previously described in the literature. We speculate that subtotal deafferance or defective motor efference after stroke may manifest intermittently as a PL.

  8. Mathematical phantoms for use in reassessment of radiation doses to Japanese atomic-bomb survivors

    SciTech Connect

    Cristy, M.

    1985-07-01

    In 1972 committees of the United Nations and the US National Academy of Sciencs emphasized the need for organ dose estimates on the Japanese atomic-bomb survivors. These estimates were then supplied by workers in Japan and the US, and they were used with the so-called T65D estimates of a survivor's radiation exposure to assess risk from radiation. Recently the T65D estimates have been questioned, and programs for reassessment of atomic-bomb radiation dosimetry have been started in Japan and the US. As a part of this new effort a mathematical analogue of the human body (or ''mathematical phantom''), to be used in estimating organ doses in adult survivors, is presented here. Recommendations on organ dosimetry for juvenile survivors are also presented and discussed. 57 refs., 10 figs., 6 tabs.

  9. Psychophysical correlates of phantom limb experience.

    PubMed

    Katz, J

    1992-09-01

    Phantom limb phenomena were correlated with psychophysiological measures of peripheral sympathetic nervous system activity measured at the amputation stump and contralateral limb. Amputees were assigned to one of three groups depending on whether they reported phantom limb pain, non-painful phantom limb sensations, or no phantom limb at all. Skin conductance and skin temperature were recorded continuously during two 30 minute sessions while subjects continuously monitored and rated the intensity of any phantom limb sensation or pain they experienced. The results from both sessions showed that mean skin temperature was significantly lower at the st