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Makkia RS, Nelson KH, Zaidi H, Dingfelder M. Hybrid computational pregnant female phantom construction for radiation dosimetry applications. Biomed Phys Eng Express 2022; 8. [PMID: 36137492 DOI: 10.1088/2057-1976/ac9414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/22/2022] [Indexed: 11/12/2022]
Abstract
The number of patients undergoing diagnostic radiology and radiation therapy procedures has increased drastically owing to improvements in cancer diagnosis and treatment and, consequently, patient survival. However, the risk of the occurrence of secondary malignancies due to radiation exposure remains a matter of concern. There are concerns about the fetus's health when pregnant women are exposed to and/or treated with ionizing radiation at various stages of pregnancy. We previously published three hybrid computational fetus phantoms, which contained 27 fetal organs, as a beginning point for developing the whole hybrid computational pregnant phantom set, which is the second objective of this study. An ICRP reference female voxel model was converted to a non-uniform rational basis spline (NURBS) surface model in order to construct a hybrid computational female phantom as a pregnant mother to each fetus model. Both the fetal and maternal organs were matched with ICRP-89 reference data. In order to create a complete standard pregnant computational phantom set at 20, 30, and 35 weeks of pregnancy, the model mother's reproductive organs were removed, and the fetus phantoms with appropriate placental and uterine models were added female pelvis using a 3D-modeling software. With the aid of radiological image sets that had been initially used to construct the fetus models, each fetus' position and rotation inside the uterus were carefully adjusted to represent the real fetal locations inside the uterus. The resulting fetus phantom was positioned in the appropriate location, matching the original radiological image sets. An obstetrician-gynecologist reviewed the complete internal anatomy of all fetus phantoms and the pregnant female for accuracy, and suggested changes were implemented as needed. This new set of hybrid computational pregnant phantom models has realistic anatomical details that can help evaluate fetal radiation doses where realistic fetal computational human phantoms are needed.
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Affiliation(s)
- Rasha S Makkia
- Department of Radiology and Biomedical Imaging, School of Medicine , Yale University School of Medicine Department of Radiology and Biomedical Imaging, 789 Howard Avenue, New Haven, Connecticut, 06520-8042, UNITED STATES
| | - Keith H Nelson
- Department of Obstetrics and Gynecology, Brody School of Medicine, East Carolina University, East Carolina University, Room 164 Medical Annex - Vidant Medical Center Greenville, NC 27834, Greenville, North Carolina, 27834, UNITED STATES
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, University Hospital of Geneva, 24 Rue Micheli-du-Crest, CH-1211, 4 Geneva Neuroscience Center, Geneva University, Geneva, Switzerland, Geneva, 1205 , SWITZERLAND
| | - Michael Dingfelder
- East Carolina University Department of Physics C-209 Howell Science Complex , Mailstop 563 , 1000 E. 5th Street, East Carolina University, Austin 127, Mailstop 563, Greenville, North Carolina, 27858, UNITED STATES
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2
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Zhang C, Li C, Yang L, Hou W, Du M, Wu T, Chen W. Assessment of Twin Fetal Exposure to Environmental Magnetic and Electromagnetic Fields. Bioelectromagnetics 2022; 43:160-173. [PMID: 35233784 DOI: 10.1002/bem.22397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/28/2021] [Accepted: 02/08/2022] [Indexed: 11/08/2022]
Abstract
Fetal development is vital in the human lifespan. Therefore, it is essential to characterize exposure by a series of typical environmental magnetic and electromagnetic fields. In particular, there has recently been a sharp increase in the twin birth rate. However, lack of appropriate models has prohibited dosimetric evaluation, restricting characterization of the impact of these environmental factors on twins. The present study developed two whole-body pregnant models of 31 and 32 weeks of gestation with twin fetuses and explored several typical exposure scenarios, including 50-Hz uniform magnetic field exposure, local 125-kHz magnetic field (MF), and 13.56-MHz electromagnetic field exposure, as well as wideband planewave radiofrequency (RF) exposure from 20 to 6000 MHz. Finally, dosimetric results were derived. Compared to the singleton pregnancy with similar weeks of gestation, twin fetuses were overexposed at 50-Hz uniform MF, but they were probably underexposed in the RF scenarios with frequencies for wireless communications. Furthermore, the twin fetuses manifested large dosimetric variability compared to the singleton, which was attributed to the incident direction and fetal position. Based on the analysis, the dosimetric results over the entire gestation period were estimated. The results can be helpful to estimate the risk of twin-fetal exposure to electromagnetic fields and examine the conservativeness of the international guidelines.© 2022 Bioelectromagnetics Society.
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Affiliation(s)
- Chen Zhang
- China Academy of Information and Communications Technology, Beijing, China
| | - Congsheng Li
- China Academy of Information and Communications Technology, Beijing, China
| | - Lei Yang
- China Academy of Information and Communications Technology, Beijing, China
| | - Wenjing Hou
- Department of Radiology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Mingshan Du
- Department of Radiology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Tongning Wu
- China Academy of Information and Communications Technology, Beijing, China
| | - Wei Chen
- Department of Radiology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
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3
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Abaci Turk E, Yetisir F, Adalsteinsson E, Gagoski B, Guerin B, Grant PE, Wald LL. Individual variation in simulated fetal SAR assessed in multiple body models. Magn Reson Med 2019; 83:1418-1428. [PMID: 31626373 DOI: 10.1002/mrm.28006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 08/23/2019] [Accepted: 08/30/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE We generate 12 models from 4 pregnant individuals to evaluate individual differences in local specific absorption rate (SAR) for differing body habitus and fetal and maternal positions. METHODS Structural MR images from 4 pregnant subjects (including supine and left-lateral maternal positions) were manually segmented to create 12 body models by rotating the fetus, modifying the fat content, and altering the maternal arm position in 1 of the subjects. Electromagnetic simulations modeled at 3 Tesla determined the average and peak local SAR in the maternal trunk, fetus, fetal brain, and amniotic fluid. RESULTS We observed a significant range of fetal and maternal peak local SAR across the models (maternal trunk: 19.14-44.03 watts/kg, fetus: 9.93-18.79 watts/kg, fetal brain 3.36-10.3 watts/kg). We found that maternal body habitus changes introduced a significant variation in the maternal peak local SAR but not the fetal local SAR. However, the maternal position (either rotating the mother to left-lateral position or altering the arm position) introduced changes in fetal peak local SAR (range: 11.9-17.9 watts/kg). Rotating the fetus also introduced variation in the fetal and fetal brain peak local SAR. CONCLUSION The observed variation in SAR emphasizes the need for more anatomical models to enable better safety management of individuals during fetal MRI, including a wider range of gestational ages.
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Affiliation(s)
- Esra Abaci Turk
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Filiz Yetisir
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Elfar Adalsteinsson
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Borjan Gagoski
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts
| | - Lawrence L Wald
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts.,Harvard Medical School, Boston, Massachusetts
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4
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Chiaramello E, Le Brusquet L, Parazzini M, Fiocchi S, Bonato M, Ravazzani P. 3D space‐dependent models for stochastic dosimetry applied to exposure to low frequency magnetic fields. Bioelectromagnetics 2019; 40:170-179. [DOI: 10.1002/bem.22179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 02/21/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Emma Chiaramello
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle TelecomunicazioniCNRMilanoItaly
| | - Laurent Le Brusquet
- Laboratoire des Signaux et Systèmes (UMR CNRS 8506)Centrale Supelec, CNRS, Univ Paris‐SudUniversité Paris‐SaclayFrance
| | - Marta Parazzini
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle TelecomunicazioniCNRMilanoItaly
| | - Serena Fiocchi
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle TelecomunicazioniCNRMilanoItaly
| | - Marta Bonato
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle TelecomunicazioniCNRMilanoItaly
- Dipartimento di ElettronicaInformazione e Bioingegneria DEIBPolitecnico di MilanoMilanoItaly
| | - Paolo Ravazzani
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle TelecomunicazioniCNRMilanoItaly
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5
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Kibret B, Premaratne M, Sullivan C, Thomson RH, Fitzgerald PB. Electroconvulsive therapy (ECT) during pregnancy: quantifying and assessing the electric field strength inside the foetal brain. Sci Rep 2018; 8:4128. [PMID: 29515221 PMCID: PMC5841342 DOI: 10.1038/s41598-018-22528-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 02/26/2018] [Indexed: 11/12/2022] Open
Abstract
Electroconvulsive therapy (ECT) is an effective treatment option for severe mental illness during pregnancy. However, there is little knowledge about the amount of electric field produced inside the foetus, which is important to understand the effects of ECT on the foetal excitable tissues. Thus, in this paper, the electric field strength inside the foetus was computed and compared to the basic restriction of the International Commission for Non-Ionizing Radiation Protection (ICNIRP). A computational human phantom representing a 30-weeks pregnant female, four types of electrode placements and a range of stimulus pulse width (0.25 ms-2 ms) and frequency (10 Hz-140 Hz) were used to compute the electric field inside the foetus. A linear relationship between the maximum electric field inside the foetal brain and the electrode current was derived. The results suggest that, considering the maximum current output, pulse width, and frequency range of constant-current ECT devices, the electric field produced inside the foetal brain is most likely below the ICNIRP basic restriction. This is based on the practical scenario of a 30-weeks foetus with a bottom-up and head-down foetal position and the mother taller than 1.62 m.
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Affiliation(s)
- Behailu Kibret
- Advanced Computing and Simulation Laboratory (AχL), Department of Electrical and Computer Systems Engineering, Monash University, Clayton, 3800, Victoria, Australia.
| | - Malin Premaratne
- Advanced Computing and Simulation Laboratory (AχL), Department of Electrical and Computer Systems Engineering, Monash University, Clayton, 3800, Victoria, Australia
| | - Caley Sullivan
- Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and the Alfred, 607 St Kilda Rd, Melbourne, 3004, Victoria, Australia
| | - Richard H Thomson
- Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and the Alfred, 607 St Kilda Rd, Melbourne, 3004, Victoria, Australia
| | - Paul B Fitzgerald
- Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and the Alfred, 607 St Kilda Rd, Melbourne, 3004, Victoria, Australia
- Epworth Healthcare, The Epworth Clinic and Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and the Alfred, 888 Toorak Rd, Camberwell, 3124 Victoria, Australia
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6
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Fiocchi S, Chiaramello E, Parazzini M, Ravazzani P. Influence of tissue conductivity on foetal exposure to extremely low frequency magnetic fields at 50 Hz using stochastic dosimetry. PLoS One 2018; 13:e0192131. [PMID: 29415005 PMCID: PMC5802904 DOI: 10.1371/journal.pone.0192131] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 01/17/2018] [Indexed: 11/19/2022] Open
Abstract
Human exposure to extremely low frequency magnetic fields (ELF-MF) at 50 Hz is still a topic of great interest due to the possible correlation with childhood leukaemia. The estimation of induced electric fields in human tissues exposed to electromagnetic fields (EMFs) strictly depends on several variables which include the dielectric properties of the tissues. In this paper, the influence of the conductivity assignment to foetal tissues at different gestational ages on the estimation of the induced electric field due to ELF-MF exposure at 50 Hz has been quantified by means of a stochastic approach using polynomial chaos theory. The range of variation in conductivity values for each foetal tissue at each stage of pregnancy have been defined through three empirical approaches and the induced electric field in each tissue has been modelled through stochastic dosimetry. The main results suggest that both the peak and median induced electric fields in foetal fat vary by more than 8% at all gestational ages. On the contrary, the electric field induced in foetal brain does not seem to be significantly affected by conductivity data changes. The maximum exposure levels, in terms of the induced electric field found in each specific tissue, were found to be significantly below the basic restrictions indicated in the ICNIRP Guidelines, 2010.
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Affiliation(s)
- Serena Fiocchi
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell’Informazione e delle Telecomunicazioni IEIIT, Milan, Italy
| | - Emma Chiaramello
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell’Informazione e delle Telecomunicazioni IEIIT, Milan, Italy
| | - Marta Parazzini
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell’Informazione e delle Telecomunicazioni IEIIT, Milan, Italy
| | - Paolo Ravazzani
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell’Informazione e delle Telecomunicazioni IEIIT, Milan, Italy
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7
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Stochastic Dosimetry for the Assessment of Children Exposure to Uniform 50 Hz Magnetic Field with Uncertain Orientation. BIOMED RESEARCH INTERNATIONAL 2017; 2017:4672124. [PMID: 29226139 PMCID: PMC5684611 DOI: 10.1155/2017/4672124] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 09/15/2017] [Accepted: 10/04/2017] [Indexed: 11/17/2022]
Abstract
This study focused on the evaluation of the exposure of children aging from five to fourteen years to 50 Hz homogenous magnetic field uncertain orientation using stochastic dosimetry. Surrogate models allowed assessing how the variation of the orientation of the magnetic field influenced the induced electric field in each tissue of the central nervous system (CNS) and in the peripheral nervous system (PNS) of children. Results showed that the electric field induced in CNS and PNS tissues of children were within the ICNIRP basic restrictions for general public and that no significant difference was found in the level of exposure of children of different ages when considering 10000 possible orientations of the magnetic field. A "mean stochastic model," useful to estimate the level of exposure in each tissue of a representative child in the range of age from five to fourteen years, was developed. In conclusion, this study was useful to deepen knowledge about the ELF-MF exposure, including the evaluation of variable and uncertain conditions, thus representing a step towards a more realistic characterization of the exposure to EMF.
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8
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Yanamadala J, Noetscher GM, Makarov SN, Pascual-Leone A. Estimates of peak electric fields induced by Transcranial magnetic stimulation in pregnant women as patients using an FEM full-body model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:1441-1444. [PMID: 29060149 DOI: 10.1109/embc.2017.8037105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Transcranial magnetic stimulation (TMS) for treatment of depression during pregnancy is an appealing alternative to fetus-threatening drugs. However, no studies to date have been performed that evaluate the safety of TMS for a pregnant mother patient and her fetus. A full-body FEM model of a pregnant woman with about 100 tissue parts has been developed specifically for the present study. This model allows accurate computations of induced electric field in every tissue given different locations of a shape-eight coil, a biphasic pulse, common TMS pulse durations, and using different values of the TMS intensity measured in SMT (Standard Motor Threshold) units. Our simulation results estimate the maximum peak values of the electric field in the fetal area for every fetal tissue separately and for the TMS intensity of one SMT unit.
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9
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Makarov SN, Noetscher GM, Yanamadala J, Piazza MW, Louie S, Prokop A, Nazarian A, Nummenmaa A. Virtual Human Models for Electromagnetic Studies and Their Applications. IEEE Rev Biomed Eng 2017; 10:95-121. [PMID: 28682265 PMCID: PMC10502908 DOI: 10.1109/rbme.2017.2722420] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Numerical simulation of electromagnetic, thermal, and mechanical responses of the human body to different stimuli in magnetic resonance imaging safety, antenna research, electromagnetic tomography, and electromagnetic stimulation is currently limited by the availability of anatomically adequate and numerically efficient cross-platform computational models or "virtual humans." The objective of this study is to provide a comprehensive review of modern human models and body region models available in the field and their important features.
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Affiliation(s)
- Sergey N. Makarov
- ECE Dept., Worcester Polytechnic Institute, Worcester, MA 01609; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 ()
| | - Gregory M. Noetscher
- ECE Dept., Worcester Polytechnic Institute, Worcester, MA 01609; Neva Electromagnetics, LLC., Yarmouth Port, MA 02675 ()
| | | | | | | | | | - Ara Nazarian
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02675 ()
| | - Aapo Nummenmaa
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 ()
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10
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Chen X, Steckner M. Electromagnetic computation and modeling in MRI. Med Phys 2017; 44:1186-1203. [PMID: 28079264 DOI: 10.1002/mp.12103] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 09/26/2016] [Accepted: 01/07/2017] [Indexed: 12/13/2022] Open
Abstract
Electromagnetic (EM) computational modeling is used extensively during the development of a Magnetic Resonance Imaging (MRI) scanner, its installation, and use. MRI, which relies on interactions between nuclear magnetic moments and the applied magnetic fields, uses a range of EM tools to optimize all of the magnetic fields required to produce the image. The main field magnet is designed to exacting specifications but challenges in manufacturing, installation, and use require additional tools to maintain target operational performance. The gradient magnetic fields, which provide the primary signal localization mechanism, are designed under another set of complex design trade-offs which include conflicting imaging performance specifications and patient physiology. Gradients are largely impervious to external influences, but are also used to enhance main field operational performance. The radiofrequency (RF) magnetic fields, which are used to elicit the signals fundamental to the MR image, are a challenge to optimize for a host of reasons that include patient safety, image quality, cost optimization, and secondary signal localization capabilities. This review outlines these issues and the EM modeling used to optimize MRI system performance.
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Affiliation(s)
- Xin Chen
- Toshiba Medical Research Institute USA, Inc. 777 Beta Drive, Mayfield Village, OH, 44143, USA
| | - Michael Steckner
- Toshiba Medical Research Institute USA, Inc. 777 Beta Drive, Mayfield Village, OH, 44143, USA
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11
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Liorni I, Parazzini M, Fiocchi S, Ravazzani P. Study of the influence of the orientation of a 50-Hz magnetic field on fetal exposure using polynomial chaos decomposition. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 12:5934-53. [PMID: 26024363 PMCID: PMC4483680 DOI: 10.3390/ijerph120605934] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/22/2015] [Indexed: 11/16/2022]
Abstract
Human exposure modelling is a complex topic, because in a realistic exposure scenario, several parameters (e.g., the source, the orientation of incident fields, the morphology of subjects) vary and influence the dose. Deterministic dosimetry, so far used to analyze human exposure to electromagnetic fields (EMF), is highly time consuming if the previously-mentioned variations are considered. Stochastic dosimetry is an alternative method to build analytical approximations of exposure at a lower computational cost. In this study, it was used to assess the influence of magnetic flux density (B) orientation on fetal exposure at 50 Hz by polynomial chaos (PC). A PC expansion of induced electric field (E) in each fetal tissue at different gestational ages (GA) was built as a function of B orientation. Maximum E in each fetal tissue and at each GA was estimated for different exposure configurations and compared with the limits of the International Commission of Non-Ionising Radiation Protection (ICNIRP) Guidelines 2010. PC theory resulted in an efficient tool to build accurate approximations of E in each fetal tissue. B orientation strongly influenced E, with a variability across tissues from 10% to 43% with respect to the mean value. However, varying B orientation, maximum E in each fetal tissue was below the limits of ICNIRP 2010 at all GAs.
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Affiliation(s)
- Ilaria Liorni
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
- Dipartimento di Elettronica, Informazione e Bioingegneria DEIB, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Marta Parazzini
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Serena Fiocchi
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Paolo Ravazzani
- CNR Consiglio Nazionale delle Ricerche, Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
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12
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Fiocchi S, Liorni I, Parazzini M, Ravazzani P. Assessment of foetal exposure to the homogeneous magnetic field harmonic spectrum generated by electricity transmission and distribution networks. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 12:3667-90. [PMID: 25837346 PMCID: PMC4410209 DOI: 10.3390/ijerph120403667] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/23/2015] [Accepted: 03/27/2015] [Indexed: 11/16/2022]
Abstract
During the last decades studies addressing the effects of exposure to Extremely Low Frequency Electromagnetic Fields (ELF-EMF) have pointed out a possible link between those fields emitted by power lines and childhood leukaemia. They have also stressed the importance of also including in the assessment the contribution of frequency components, namely harmonics, other than the fundamental one. Based on the spectrum of supply voltage networks allowed by the European standard for electricity quality assessment, in this study the exposure of high-resolution three-dimensional models of foetuses to the whole harmonic content of a uniform magnetic field with a fundamental frequency of 50 Hz, was assessed. The results show that the main contribution in terms of induced electric fields to the foetal exposure is given by the fundamental frequency component. The harmonic components add some contributions to the overall level of electric fields, however, due to the extremely low permitted amplitude of the harmonic components with respect to the fundamental, their amplitudes are low. The level of the induced electric field is also much lower than the limits suggested by the guidelines for general public exposure, when the amplitude of the incident magnetic field is set at the maximum permitted level.
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Affiliation(s)
- Serena Fiocchi
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, CNR Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Ilaria Liorni
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, CNR Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
- Dipartimento di Elettronica, Informazione e Bioingegneria DEIB, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Marta Parazzini
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, CNR Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Paolo Ravazzani
- Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni IEIIT, CNR Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
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13
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Li C, Wu T. Dosimetry of infant exposure to power-frequency magnetic fields: Variation of 99th percentile induced electric field value by posture and skin-to-skin contact. Bioelectromagnetics 2015; 36:204-18. [DOI: 10.1002/bem.21899] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 01/16/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Congsheng Li
- China Academy of Telecommunication Research; Ministry of Industry and Information Technology; Beijing China
- College of Computer and Communication Engineering; Beijing University of Science and Technology; Beijing China
| | - Tongning Wu
- China Academy of Telecommunication Research; Ministry of Industry and Information Technology; Beijing China
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14
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Liorni I, Parazzini M, Fiocchi S, Guadagnin V, Ravazzani P. Polynomial Chaos decomposition applied to stochastic dosimetry: study of the influence of the magnetic field orientation on the pregnant woman exposure at 50 Hz. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:342-4. [PMID: 25569967 DOI: 10.1109/embc.2014.6943599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Polynomial Chaos (PC) is a decomposition method used to build a meta-model, which approximates the unknown response of a model. In this paper the PC method is applied to the stochastic dosimetry to assess the variability of human exposure due to the change of the orientation of the B-field vector respect to the human body. In detail, the analysis of the pregnant woman exposure at 7 months of gestational age is carried out, to build-up a statistical meta-model of the induced electric field for each fetal tissue and in the fetal whole-body by means of the PC expansion as a function of the B-field orientation, considering a uniform exposure at 50 Hz.
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15
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Dosimetric study of fetal exposure to uniform magnetic fields at 50 Hz. Bioelectromagnetics 2014; 35:580-97. [DOI: 10.1002/bem.21878] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 07/24/2014] [Indexed: 11/07/2022]
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16
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Xu XG. An exponential growth of computational phantom research in radiation protection, imaging, and radiotherapy: a review of the fifty-year history. Phys Med Biol 2014; 59:R233-302. [PMID: 25144730 PMCID: PMC4169876 DOI: 10.1088/0031-9155/59/18/r233] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Radiation dose calculation using models of the human anatomy has been a subject of great interest to radiation protection, medical imaging, and radiotherapy. However, early pioneers of this field did not foresee the exponential growth of research activity as observed today. This review article walks the reader through the history of the research and development in this field of study which started some 50 years ago. This review identifies a clear progression of computational phantom complexity which can be denoted by three distinct generations. The first generation of stylized phantoms, representing a grouping of less than dozen models, was initially developed in the 1960s at Oak Ridge National Laboratory to calculate internal doses from nuclear medicine procedures. Despite their anatomical simplicity, these computational phantoms were the best tools available at the time for internal/external dosimetry, image evaluation, and treatment dose evaluations. A second generation of a large number of voxelized phantoms arose rapidly in the late 1980s as a result of the increased availability of tomographic medical imaging and computers. Surprisingly, the last decade saw the emergence of the third generation of phantoms which are based on advanced geometries called boundary representation (BREP) in the form of Non-Uniform Rational B-Splines (NURBS) or polygonal meshes. This new class of phantoms now consists of over 287 models including those used for non-ionizing radiation applications. This review article aims to provide the reader with a general understanding of how the field of computational phantoms came about and the technical challenges it faced at different times. This goal is achieved by defining basic geometry modeling techniques and by analyzing selected phantoms in terms of geometrical features and dosimetric problems to be solved. The rich historical information is summarized in four tables that are aided by highlights in the text on how some of the most well-known phantoms were developed and used in practice. Some of the information covered in this review has not been previously reported, for example, the CAM and CAF phantoms developed in 1970s for space radiation applications. The author also clarifies confusion about 'population-average' prospective dosimetry needed for radiological protection under the current ICRP radiation protection system and 'individualized' retrospective dosimetry often performed for medical physics studies. To illustrate the impact of computational phantoms, a section of this article is devoted to examples from the author's own research group. Finally the author explains an unexpected finding during the course of preparing for this article that the phantoms from the past 50 years followed a pattern of exponential growth. The review ends on a brief discussion of future research needs (a supplementary file '3DPhantoms.pdf' to figure 15 is available for download that will allow a reader to interactively visualize the phantoms in 3D).
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Affiliation(s)
- X George Xu
- Rensselaer Polytechnic Institute Troy, New York, USA
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17
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Liorni I, Parazzini M, Fiocchi S, Ravazzani P. Exposure of high resolution fetuses in advanced pregnant woman models at different stages of pregnancy to uniform magnetic fields at the frequency of 50 Hz. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:4525-8. [PMID: 24110740 DOI: 10.1109/embc.2013.6610553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Extremely low frequency magnetic fields (ELF-MF) have been considered as a possible risk factor for childhood leukemia by several epidemiological studies. In this work the exposure assessment of fetuses at 3, 7 and 9 months of Gestational Age (GA) to differently polarized uniform magnetic fields at the frequency of 50 Hz by means of high resolution numerical models of pregnant women is carried out. This set of models is used to analyze the fetal tissue-specific induced electric fields and current densities as a function of both the incident magnetic field polarization and the GA.
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18
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Bellieni CV, Pinto I, Bogi A, Zoppetti N, Andreuccetti D, Buonocore G. Exposure to electromagnetic fields from laptop use of "laptop" computers. ARCHIVES OF ENVIRONMENTAL & OCCUPATIONAL HEALTH 2012; 67:31-36. [PMID: 22315933 DOI: 10.1080/19338244.2011.564232] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Portable computers are often used at tight contact with the body and therefore are called "laptop." The authors measured electromagnetic fields (EMFs) laptop computers produce and estimated the induced currents in the body, to assess the safety of laptop computers. The authors evaluated 5 commonly used laptop of different brands. They measured EMF exposure produced and, using validated computerized models, the authors exploited the data of one of the laptop computers (LTCs) to estimate the magnetic flux exposure of the user and of the fetus in the womb, when the laptop is used at close contact with the woman's womb. In the LTCs analyzed, EMF values (range 1.8-6 μT) are within International Commission on Non-Ionizing Radiation (NIR) Protection (ICNIRP) guidelines, but are considerably higher than the values recommended by 2 recent guidelines for computer monitors magnetic field emissions, MPR II (Swedish Board for Technical Accreditation) and TCO (Swedish Confederation of Professional Employees), and those considered risky for tumor development. When close to the body, the laptop induces currents that are within 34.2% to 49.8% ICNIRP recommendations, but not negligible, to the adult's body and to the fetus (in pregnant women). On the contrary, the power supply induces strong intracorporal electric current densities in the fetus and in the adult subject, which are respectively 182-263% and 71-483% higher than ICNIRP 98 basic restriction recommended to prevent adverse health effects. Laptop is paradoxically an improper site for the use of a LTC, which consequently should be renamed to not induce customers towards an improper use.
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Affiliation(s)
- C V Bellieni
- Department of Pediatrics, Obstetrics and Reproduction Medicine, University of Siena, Italy.
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19
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Wiart J, Hadjem A, Varsier N, Conil E. Numerical dosimetry dedicated to children RF exposure. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:421-7. [DOI: 10.1016/j.pbiomolbio.2011.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 10/02/2011] [Indexed: 10/16/2022]
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20
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Zoppetti N, Andreuccetti D, Bellieni C, Bogi A, Pinto I. Evaluation and characterization of fetal exposures to low frequency magnetic fields generated by laptop computers. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:456-63. [PMID: 22019904 DOI: 10.1016/j.pbiomolbio.2011.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 10/02/2011] [Indexed: 10/16/2022]
Abstract
Portable - or "laptop" - computers (LCs) are widely and increasingly used all over the world. Since LCs are often used in tight contact with the body even by pregnant women, fetal exposures to low frequency magnetic fields generated by these units can occur. LC emissions are usually characterized by complex waveforms and are often generated by the main AC power supply (when connected) and by the display power supply sub-system. In the present study, low frequency magnetic field emissions were measured for a set of five models of portable computers. For each of them, the magnetic flux density was characterized in terms not just of field amplitude, but also of the so called "weighted peak" (WP) index, introduced in the 2003 ICNIRP Statement on complex waveforms and confirmed in the 2010 ICNIRP Guidelines for low frequency fields. For the model of LC presenting the higher emission, a deeper analysis was also carried out, using numerical dosimetry techniques to calculate internal quantities (current density and in-situ electric field) with reference to a digital body model of a pregnant woman. Since internal quantities have complex waveforms too, the concept of WP index was extended to them, considering the ICNIRP basic restrictions defined in the 1998 Guidelines for the current density and in the 2010 Guidelines for the in-situ electric field. Induced quantities and WP indexes were computed using an appropriate original formulation of the well known Scalar Potential Finite Difference (SPFD) numerical method for electromagnetic dosimetry in quasi-static conditions.
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Affiliation(s)
- Nicola Zoppetti
- CNR, Institute of Applied Physics Nello Carrara (IFAC-CNR), Sesto Fiorentino (FI), Italy.
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21
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Whole-body pregnant woman modeling by digital geometry processing with detailed uterofetal unit based on medical images. IEEE Trans Biomed Eng 2010; 57:2346-58. [DOI: 10.1109/tbme.2010.2053367] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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McIntosh RL, Deppeler L, Oliva M, Parente J, Tambuwala F, Turner S, Winship D, Wood AW. Comparison of radiofrequency exposure of a mouse dam and foetuses at 900 MHz. Phys Med Biol 2010; 55:N111-22. [PMID: 20107247 DOI: 10.1088/0031-9155/55/4/n02] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In vivo studies involving radiofrequency (RF) exposure of rodents require detailed dosimetric analysis to enable correct interpretation of biological outcomes. Detailed anatomical models of mice--a female, a pregnant female, a male and a foetus--have been developed for analyses using finite difference numerical techniques. The mouse models, consisting of 49 tissues, will be made freely available to the research community. In this note, the pregnant mouse model, which included eight mature foetuses, was utilized specifically to consider (a) the RF dosimetry in a radial cavity exposure system operated at a frequency of 900 MHz and (b) a 900 MHz plane wave exposure. A comparison was made between the exposure of the mouse dam and the foetuses as specified by the specific energy absorption rate (SAR) and the resultant temperature change. In general, the SAR levels in the foetuses were determined to be slightly lower (around 14% lower than the average values of the dam) and the peak temperature increase was significantly lower (45%) than the values in the dam.
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Affiliation(s)
- Robert L McIntosh
- Australian Centre for Radiofrequency Bioeffects Research, Hawthorn, VIC, 3122, Australia.
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23
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Kawai H, Nagaoka T, Watanabe S, Saito K, Takahashi M, Ito K. Computational dosimetry in embryos exposed to electromagnetic plane waves over the frequency range of 10 MHz-1.5 GHz. Phys Med Biol 2010; 55:N1-11. [PMID: 20009180 DOI: 10.1088/0031-9155/55/1/n01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This paper presents calculated specific absorption rate (SAR) dosimetry in 4 and 8 week Japanese pregnant-woman models exposed to plane waves over the frequency range of 10 MHz-1.5 GHz. Two types of 2 mm spatial-resolution pregnant-woman models comprised a woman model, which is similar to the average-sized Japanese adult female in height and weight, with a cubic (4 week) embryo or spheroidal (8 week) one. The averaged SAR in the embryos exposed to vertically and horizontally polarized plane waves at four kinds of propagation directions are calculated from 10 MHz to 1.5 GHz. The results indicate that the maximum average SAR in the embryos exposed to plane waves is lower than 0.08 W kg(-1) when the incident power density is at the reference level of ICNIRP guideline for general public environment.
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Affiliation(s)
- Hiroki Kawai
- National Institute of Information and Communications Technology, 4-2-1 Nukuikitamachi, Koganei, Tokyo 184-8795, Japan.
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24
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Tachas NJ, Samaras T, Baskourelos K, Sahalos JN. Effects of skeletal muscle anisotropy on induced currents from low-frequency magnetic fields. Phys Med Biol 2009; 54:N541-7. [DOI: 10.1088/0031-9155/54/23/n02] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Hirata A, Wake K, Watanabe S, Taki M. In-situ electric field and current density in Japanese male and female models for uniform magnetic field exposures. RADIATION PROTECTION DOSIMETRY 2009; 135:272-275. [PMID: 19628703 DOI: 10.1093/rpd/ncp117] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The present study quantified the in situ electric field and induced current density in anatomically based numeric Japanese male and female models for exposure to extremely low-frequency magnetic fields. A quasi-static FDTD method was applied to analyse this problem. The computational results obtained herein reveal that the 99 th percentile value of the in situ electric field in the nerve tissue and the current density averaged over an area of 1 cm(2) of the nerve tissue (excluding non-nerve tissues in the averaging region) in the female models were less than 35 and 25 %, respectively. These induced quantities in the Japanese models were smaller than those for European models reported in a previous study, which is mainly due to the difference in cross-sectional area of the body.
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Affiliation(s)
- Akimasa Hirata
- National Institute of Information and Communications Technology, EMC group, Tokyo, Japan.
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26
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Hybrid 3D pregnant woman and fetus modeling from medical imaging for dosimetry studies. Int J Comput Assist Radiol Surg 2009; 5:49-56. [PMID: 20033512 DOI: 10.1007/s11548-009-0381-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Accepted: 06/08/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE Numerical simulations studying the interactions between radiations and biological tissues require the use of three-dimensional models of the human anatomy at various ages and in various positions. Several detailed and flexible models exist for adults and children and have been extensively used for dosimetry. On the other hand, progress of simulation studies focusing on pregnant women and the fetus have been limited by the fact that only a small number of models exist with rather coarse anatomical details and a poor representation of the anatomical variability of the fetus shape and its position over the entire gestation. METHODS In this paper, we propose a new computational framework to generate 3D hybrid models of pregnant women, composed of fetus shapes segmented from medical images and a generic maternal body envelope representing a synthetic woman scaled to the dimension of the uterus. The computational framework includes the following tasks: image segmentation, contour regularization, mesh-based surface reconstruction, and model integration. RESULTS A series of models was created to represent pregnant women at different gestational stages and with the fetus in different positions, all including detailed tissues of the fetus and the utero-fetal unit, which play an important role in dosimetry. These models were anatomically validated by clinical obstetricians and radiologists who verified the accuracy and representativeness of the anatomical details, and the positioning of the fetus inside the maternal body. CONCLUSION The computational framework enables the creation of detailed, realistic, and representative fetus models from medical images, directly exploitable for dosimetry simulations.
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27
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Pediaditis M, Leitgeb N, Cech R. RF-EMF exposure of fetus and mother during magnetic resonance imaging. Phys Med Biol 2008; 53:7187-95. [PMID: 19033645 DOI: 10.1088/0031-9155/53/24/012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Magnetic resonance imaging (MRI) avoids risks of genetic damage but may be associated with excess heating of body tissues. To investigate the exposure to MRI radio-frequency (RF) electromagnetic fields (EMF), low-pass and high-pass birdcage coils were simulated and the whole-body pregnant woman model SILVY used to determine local and whole-body specific absorption rates (SAR) in mother and fetus. Resonant RF-EMF of MRI devices were investigated at 0.3, 1, 1.5, 2, 3 and 4 T. Results allow extrapolation also to higher fields. They showed that local SAR in mother's trunk reaches exposure limits first. However, data show that during abdominal MRI meeting exposure limits of the mother is not sufficient to protect the fetus if limits of the general populations are applied to it. In that case fetal whole-body SAR exceeds limits by 7.4-fold. It is up to the physician and/or the ethics commission to decide upon justification for abdominal MRI of pregnant women if limits are exceeded. The results indicate the need for specifically addressing fetal exposure to EMF and elaborating general recommendations by radiation protection bodies.
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Affiliation(s)
- M Pediaditis
- Institute of Health Care Engineering with European Notified Body of Medical Devices, Graz University of Technology, Inffeldgasse 18, 8010 Graz, Austria
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28
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Shi CY, Xu XG, Stabin MG. SAF values for internal photon emitters calculated for the RPI-P pregnant-female models using Monte Carlo methods. Med Phys 2008; 35:3215-24. [PMID: 18697546 DOI: 10.1118/1.2936414] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Estimates of radiation absorbed doses from radionuclides internally deposited in a pregnant woman and her fetus are very important due to elevated fetal radiosensitivity. This paper reports a set of specific absorbed fractions (SAFs) for use with the dosimetry schema developed by the Society of Nuclear Medicine's Medical Internal Radiation Dose (MIRD) Committee. The calculations were based on three newly constructed pregnant female anatomic models, called RPI-P3, RPI-P6, and RPI-P9, that represent adult females at 3-, 6-, and 9-month gestational periods, respectively. Advanced Boundary REPresentation (BREP) surface-geometry modeling methods were used to create anatomically realistic geometries and organ volumes that were carefully adjusted to agree with the latest ICRP reference values. A Monte Carlo user code, EGS4-VLSI, was used to simulate internal photon emitters ranging from 10 keV to 4 MeV. SAF values were calculated and compared with previous data derived from stylized models of simplified geometries and with a model of a 7.5-month pregnant female developed previously from partial-body CT images. The results show considerable differences between these models for low energy photons, but generally good agreement at higher energies. These differences are caused mainly by different organ shapes and positions. Other factors, such as the organ mass, the source-to-target-organ centroid distance, and the Monte Carlo code used in each study, played lesser roles in the observed differences in these. Since the SAF values reported in this study are based on models that are anatomically more realistic than previous models, these data are recommended for future applications as standard reference values in internal dosimetry involving pregnant females.
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Affiliation(s)
- C Y Shi
- Department of Radiation Oncology, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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29
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Bednarz B, Xu XG. A feasibility study to calculate unshielded fetal doses to pregnant patients in 6-MV photon treatments using Monte Carlo methods and anatomically realistic phantoms. Med Phys 2008; 35:3054-61. [PMID: 18697528 PMCID: PMC2809713 DOI: 10.1118/1.2938519] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A Monte Carlo-based procedure to assess fetal doses from 6-MV external photon beam radiation treatments has been developed to improve upon existing techniques that are based on AAPM Task Group Report 36 published in 1995 [M. Stovall et al., Med. Phys. 22, 63-82 (1995)]. Anatomically realistic models of the pregnant patient representing 3-, 6-, and 9-month gestational stages were implemented into the MCNPX code together with a detailed accelerator model that is capable of simulating scattered and leakage radiation from the accelerator head. Absorbed doses to the fetus were calculated for six different treatment plans for sites above the fetus and one treatment plan for fibrosarcoma in the knee. For treatment plans above the fetus, the fetal doses tended to increase with increasing stage of gestation. This was due to the decrease in distance between the fetal body and field edge with increasing stage of gestation. For the treatment field below the fetus, the absorbed doses tended to decrease with increasing gestational stage of the pregnant patient, due to the increasing size of the fetus and relative constant distance between the field edge and fetal body for each stage. The absorbed doses to the fetus for all treatment plans ranged from a maximum of 30.9 cGy to the 9-month fetus to 1.53 cGy to the 3-month fetus. The study demonstrates the feasibility to accurately determine the absorbed organ doses in the mother and fetus as part of the treatment planning and eventually in risk management.
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Affiliation(s)
- Bryan Bednarz
- Nuclear Engineering and Engineering Physics Program, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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30
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Katja — the 24th week of virtual pregnancy for dosimetric calculations. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2008. [DOI: 10.2478/v10013-008-0002-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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31
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Cech R, Leitgeb N, Pediaditis M. Current densities in a pregnant woman model induced by simultaneous ELF electric and magnetic field exposure. Phys Med Biol 2007; 53:177-86. [PMID: 18182695 DOI: 10.1088/0031-9155/53/1/012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pregnant woman model SILVY was studied to ascertain to what extent the electric current densities induced by 50 Hz homogeneous electric and magnetic fields increase in the case of simultaneous exposure. By vectorial addition of the electric current densities, it could be shown that under worst case conditions the basic restrictions recommended by ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines are exceeded within the central nervous system (CNS) of the mother, whereas in sole field exposure they are not. However, within the foetus the induced current densities do not comply with basic restrictions, either from single reference-level electric fields or from simultaneous exposure to electric and magnetic fields. Basic limits were considerably exceeded.
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Affiliation(s)
- R Cech
- Institute of Clinical Engineering, Graz University of Technology, Inffeldgasse 18, 8010 Graz, Austria.
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32
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Dimbylow P. Quandaries in the application of the ICNIRP low frequency basic restriction on current density. Phys Med Biol 2007; 53:133-45. [DOI: 10.1088/0031-9155/53/1/009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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33
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Xu XG, Taranenko V, Zhang J, Shi C. A boundary-representation method for designing whole-body radiation dosimetry models: pregnant females at the ends of three gestational periods—RPI-P3, -P6 and -P9. Phys Med Biol 2007; 52:7023-44. [DOI: 10.1088/0031-9155/52/23/017] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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34
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Nagaoka T, Togashi T, Saito K, Takahashi M, Ito K, Watanabe S. An anatomically realistic whole-body pregnant-woman model and specific absorption rates for pregnant-woman exposure to electromagnetic plane waves from 10 MHz to 2 GHz. Phys Med Biol 2007; 52:6731-45. [PMID: 17975294 DOI: 10.1088/0031-9155/52/22/012] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The numerical dosimetry of pregnant women is an important issue in electromagnetic-field safety. However, an anatomically realistic whole-body pregnant-woman model for electromagnetic dosimetry has not been developed. Therefore, we have developed a high-resolution whole-body model of pregnant women. A new fetus model including inherent tissues of pregnant women was constructed on the basis of abdominal magnetic resonance imaging data of a 26-week-pregnant woman. The whole-body pregnant-woman model was developed by combining the fetus model and a nonpregnant-woman model that was developed previously. The developed model consists of about 7 million cubical voxels of 2 mm size and is segmented into 56 tissues and organs. This pregnant-woman model is the first completely anatomically realistic voxel model that includes a realistic fetus model and enables a numerical simulation of electromagnetic dosimetry up to the gigahertz band. In this paper, we also present the basic specific absorption rate characteristics of the pregnant-woman model exposed to vertically and horizontally polarized electromagnetic waves from 10 MHz to 2 GHz.
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Affiliation(s)
- Tomoaki Nagaoka
- National Institute of Information and Communications Technology, 4-2-1 Nukuikitamachi, Koganei, Tokyo 184-8795, Japan.
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