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Wu J, Liu J. Review of the Capacity to Accurately Detect the Temperature of Human Skin Tissue Using the Microwave Radiation Method. BIOSENSORS 2024; 14:221. [PMID: 38785695 PMCID: PMC11117873 DOI: 10.3390/bios14050221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024]
Abstract
Microwave radiometry (MWR) is instrumental in detecting thermal variations in skin tissue before anatomical changes occur, proving particularly beneficial in the early diagnosis of cancer and inflammation. This study concisely traces the evolution of microwave radiometers within the medical sector. By analyzing a plethora of pertinent studies and contrasting their strengths, weaknesses, and performance metrics, this research identifies the primary factors limiting temperature measurement accuracy. The review establishes the critical technologies necessary to overcome these limitations, examines the current state and prospective advancements of each technology, and proposes comprehensive implementation strategies. The discussion elucidates that the precise measurement of human surface and subcutaneous tissue temperatures using an MWR system is a complex challenge, necessitating an integration of antenna directionality for temperature measurement, radiometer error correction, hardware configuration, and the calibration and precision of a multilayer tissue forward and inversion method. This study delves into the pivotal technologies for non-invasive human tissue temperature monitoring in the microwave frequency range, offering an effective approach for the precise assessment of human epidermal and subcutaneous temperatures, and develops a non-contact microwave protocol for gauging subcutaneous tissue temperature distribution. It is anticipated that mass-produced measurement systems will deliver substantial economic and societal benefits.
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Affiliation(s)
- Jingtao Wu
- School of Information Science and Engineering, Southeast University, Nanjing 210096, China;
| | - Jie Liu
- The Faculty of Information Technology, Beijing University of Technology, Beijing 100124, China
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2
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Medical Antennas for Microwave Radiothermometry of Biological Objects. BIOMEDICAL ENGINEERING 2023; 56:419-423. [PMID: 36819989 PMCID: PMC9933014 DOI: 10.1007/s10527-023-10248-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Indexed: 02/18/2023]
Abstract
The results of an analytical review of various antennas used in medicine are presented. Issues of modern microwave radiothermometry related to the development of new antennas are discussed, as well as possible ways to solve them. The tasks of further research aimed at creating new designs for conformal antennas and antenna arrays providing a significant expansion of the functionality and improvements in the characteristics of medical radiothermographs are formulated. The study was supported by the Russian Science Foundation (Grant No. 22-19-00113), https://rscf.ru/project/22-19-00113/.
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3
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Villa E, Aja B, de la Fuente L, Artal E, Arteaga-Marrero N, Ramos G, Ruiz-Alzola J. Multifrequency Microwave Radiometry for Characterizing the Internal Temperature of Biological Tissues. BIOSENSORS 2022; 13:25. [PMID: 36671860 PMCID: PMC9855903 DOI: 10.3390/bios13010025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
The analysis of near-field radiometry is described for characterizing the internal temperature of biological tissues, for which a system based on multifrequency pseudo-correlation-type radiometers is proposed. The approach consists of a new topology with multiple output devices that enables real-time calibration and performance assessment, recalibrating the receiver through simultaneous measurable outputs. Experimental characterization of the prototypes includes a well-defined calibration procedure, which is described and demonstrated, as well as DC conversion from the microwave input power. Regarding performance, high sensitivity is provided in all the bands with noise temperatures around 100 K, reducing the impact of the receiver on the measurements and improving its sensitivity. Calibrated temperature retrievals exhibit outstanding results for several noise sources, for which temperature deviations are lower than 0.1% with regard to the expected temperature. Furthermore, a temperature recovery test for biological tissues, such as a human forearm, provides temperature values on the order of 310 K. In summary, the radiometers design, calibration method and temperature retrieval demonstrated significant results in all bands, validating their use for biomedical applications.
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Affiliation(s)
- Enrique Villa
- Grupo Tecnología Médica IACTEC, Instituto de Astrofísica de Canarias (IAC), 38205 San Cristóbal de La Laguna, Spain
| | - Beatriz Aja
- Departamento de Ingeniería de Comunicaciones, Universidad de Cantabria, Plaza de la Ciencia s/n, 39005 Santander, Spain
| | - Luisa de la Fuente
- Departamento de Ingeniería de Comunicaciones, Universidad de Cantabria, Plaza de la Ciencia s/n, 39005 Santander, Spain
| | - Eduardo Artal
- Departamento de Ingeniería de Comunicaciones, Universidad de Cantabria, Plaza de la Ciencia s/n, 39005 Santander, Spain
| | - Natalia Arteaga-Marrero
- Grupo Tecnología Médica IACTEC, Instituto de Astrofísica de Canarias (IAC), 38205 San Cristóbal de La Laguna, Spain
| | - Gara Ramos
- Grupo Tecnología Médica IACTEC, Instituto de Astrofísica de Canarias (IAC), 38205 San Cristóbal de La Laguna, Spain
| | - Juan Ruiz-Alzola
- Grupo Tecnología Médica IACTEC, Instituto de Astrofísica de Canarias (IAC), 38205 San Cristóbal de La Laguna, Spain
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS), Universidad de Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain
- Departamento de Señales y Comunicaciones, Universidad de Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain
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4
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Tisdale K, Bringer A, Kiourti A. A Core Body Temperature Retrieval Method for Microwave Radiometry when Tissue Permittivity is Unknown. IEEE JOURNAL OF ELECTROMAGNETICS, RF AND MICROWAVES IN MEDICINE AND BIOLOGY 2022; 6:470-476. [PMID: 36439285 PMCID: PMC9696197 DOI: 10.1109/jerm.2022.3171092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
This paper presents a novel method for core temperature retrieval using microwave radiometry when complex permittivity and heat transfer parameters of the tissue layers of the human subject are unknown. Previous works present methods for core temperature retrieval, but these methods do not account for population variation in the relevant electromagnetic and thermal parameters, which can increase measurement error beyond the clinically acceptable limit of 0.5°C. Pennes' bioheat model of a six-tissue-layer human head model combined with a coherent electromagnetic model simulate experimental data. To retrieve core temperature, nonlinear least squares optimization is then used to minimize the difference between the simulated experimental data and an exponential model for physical temperature and the coherent electromagnetic model. By using 20 frequencies spanning from 1-5 GHz, core temperature is retrieved while accounting for population variation in the permittivity and thermal parameters. A Monte Carlo simulation in which the thermal parameters and permittivity vary according to literature-derived, population-representative distributions and the core body temperature varies from 18-46°C is used to assess the utility of the retrieval method. Different antenna patterns are tested to explore the effect on retrieval accuracy. The retrieval method has a retrieval error of <0.1°C when only the thermal parameters are unknown and a retrieval error of <0.5°C when the thermal parameters and permittivity are unknown, which is within the clinically acceptable error range of 0.5°C. These results help progress the field of medical microwave radiometry toward being a clinically viable noninvasive measurement that is accurate when measuring all patients.
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Affiliation(s)
- Katrina Tisdale
- The Ohio State University ElectroScience Laboratory, Columbus, OH, 43212 USA
| | - Alexandra Bringer
- The Ohio State University ElectroScience Laboratory, Columbus, OH, 43212 USA
| | - Asimina Kiourti
- The Ohio State University ElectroScience Laboratory, Columbus, OH, 43212 USA
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5
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Microminiaturization of Multichannel Multifrequency Radiographs. BIOMEDICAL ENGINEERING 2022; 56:225-229. [PMID: 36311439 PMCID: PMC9596336 DOI: 10.1007/s10527-022-10207-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 11/07/2022]
Abstract
Due to the COVID-19 epidemic, the challenge of introducing methods for investigating patients reducing or eliminating the probability of infection of medical staff is currently relevant. This article provides an analytical review of new technological approaches to organizing the work of medical personnel in carrying out auscultation of patients with COVID-19. The development and approval of such technologies is shown to have started around the world. The ubiquitous and large-scale introduction of these methods into medical practice therefore seems expedient.
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6
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Tisdale K, Bringer A, Kiourti A. Development of a Coherent Model for Radiometric Core Body Temperature Sensing. IEEE JOURNAL OF ELECTROMAGNETICS, RF AND MICROWAVES IN MEDICINE AND BIOLOGY 2022; 6:355-363. [PMID: 36034518 PMCID: PMC9400640 DOI: 10.1109/jerm.2021.3137962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This paper examines the utility of a wideband, physics-based model to determine human core body or brain temperature via microwave radiometry. Pennes's bioheat equation is applied to a six-layer human head model to generate the expected layered temperature profile during the development of a fever. The resulting temperature profile is fed into the forward electromagnetic (EM) model to determine the emitted brightness temperature at various points in time. To accurately retrieve physical temperature via radiometry, the utilized model must incorporate population variation statistics and cover a wide frequency band. The effect of human population variation on emitted brightness temperature is studied by varying the relevant thermal and EM parameters, and brightness temperature emissions are simulated from 0.1 MHz to 10 GHz. A Monte Carlo simulation combined with literature-derived statistical distributions for the thermal and EM parameters is performed to analyze population-level variation in resulting brightness temperature. Variation in thermal parameters affects the offset of the resulting brightness temperature signature, while EM parameter variation shifts the key maxima and minima of the signature. The layering of high and low permittivity layers creates these key maxima and minima via wave interference. This study is one of the first to apply a coherent model to and the first to examine the effect of population-representative variable distributions on radiometry for core temperature measurement. These results better inform the development of an on-body radiometer useful for core body temperature measurement across the human population.
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Affiliation(s)
- Katrina Tisdale
- Ohio State University ElectroScience Laboratory, Columbus, OH 43212 USA
| | - Alexandra Bringer
- Ohio State University ElectroScience Laboratory, Columbus, OH 43212 USA
| | - Asimina Kiourti
- Ohio State University ElectroScience Laboratory, Columbus, OH 43212 USA
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7
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Goryanin I, Ovchinnikov L, Vesnin S, Ivanov Y. Monitoring Protein Denaturation of Egg White Using Passive Microwave Radiometry (MWR). Diagnostics (Basel) 2022; 12:diagnostics12061498. [PMID: 35741308 PMCID: PMC9221703 DOI: 10.3390/diagnostics12061498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/08/2022] [Accepted: 06/15/2022] [Indexed: 11/16/2022] Open
Abstract
Passive microwave radiometry (MWR) is a measurement technique based on the detection of passive radiation in the microwave spectrum of different objects. When in equilibrium, this radiation is known to be proportional to the thermodynamic temperature of an emitting body. We hypothesize that living systems feature other mechanisms of emission that are based on protein unfolding and water rotational transitions. To understand the nature of these emissions, microwave radiometry was used in several in vitro experiments. In our study, we performed pilot measurements of microwave emissions from egg whites during denaturation induced by ethanol. Egg whites comprise 10% proteins, such as albumins, mucoproteins, and globulins. We observed a novel phenomenon: microwave emissions changed without a corresponding change in the water’s thermodynamic temperature. We also found striking differences between microwave emissions and thermodynamic temperature kinetics. Therefore, we hypothesize that these two processes are unrelated, contrary to what was thought before. It is known that some pathologies such as stroke or brain trauma feature increased microwave emissions. We hypothesize that this phenomenon originates from protein denaturation and is not related to the thermodynamic temperature. As such, our findings could explain the reason for the increase in microwave emissions after trauma and post mortem for the first time. These findings could be used for the development of novel diagnostics methods. The MWR method is inexpensive and does not require fluorescent or radioactive labels. It can be used in different areas of basic and applied pharmaceutical research, including in kinetics studies in biomedicine.
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Affiliation(s)
- Igor Goryanin
- Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-049, Japan
- School of Informatics, University of Edinburgh, Edinburgh EH8 9YL, UK
- Institute Experimental and Theoretical Biophysics, 142290 Pushchino, Russia
- Correspondence:
| | - Lev Ovchinnikov
- Medical Microwave Radiometry (MMWR) LTD, Edinburgh EH10 5LZ, UK; (L.O.); (S.V.)
| | - Sergey Vesnin
- Medical Microwave Radiometry (MMWR) LTD, Edinburgh EH10 5LZ, UK; (L.O.); (S.V.)
| | - Yuri Ivanov
- Institute of Biomedical Chemistry, 10, Pogodinskaya st., 119121 Moscow, Russia;
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8
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Kalinke I, Kubbutat P, Taghian Dinani S, Ambros S, Ozcelik M, Kulozik U. Critical assessment of methods for measurement of temperature profiles and heat load history in microwave heating processes-A review. Compr Rev Food Sci Food Saf 2022; 21:2118-2148. [PMID: 35338578 DOI: 10.1111/1541-4337.12940] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 02/11/2022] [Accepted: 02/24/2022] [Indexed: 12/23/2022]
Abstract
Limitations of microwave processing due to inhomogeneities of power input and energy absorption have been widely described. Over- and underheated product areas influence reproducibility, product quality, and possibly safety. Although a broad range of methods is available for temperature measurement and evaluation of time/temperature effects, none of them is sufficiently able to detect temperature differences and thermally induced effects within the product caused by inhomogeneous heating. The purpose of this review is to critically assess different methods of temperature measurement for their suitability for different microwave applications, namely metallic temperature sensors, thermal imaging, pyrometer measurement, fiber optic sensors, microwave radiometry, magnetic resonance imaging, liquid crystal thermography, thermal paper, and biological and chemical time-temperature indicators. These methods are evaluated according to their advantages and limitations, method characteristics, and potential interference with the electric field. Special attention is given to spatial resolution, accuracy, handling, and purpose of measurement, that is, development work or online production control. Differences of methods and examples of practical application and failure in microwave-assisted food processing are discussed with a special focus on microwave pasteurization and microwave-assisted drying. Based on this assessment, it is suggested that infrared cameras for measuring temperature distribution at the product surface and partially inside the product in combination with a chemical time/temperature indicator (e.g., Maillard reaction, generating heat-induced color variations, depending on local energy absorption) appear to be the most appropriate system for future practical application in microwave food process control, microwave system development, and product design. Reliable detection of inhomogeneous heating is a prerequisite to counteracte inhomogeneity by a targeted adjustment of process and product parameters in microwave applications.
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Affiliation(s)
- Isabel Kalinke
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Peter Kubbutat
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Somayeh Taghian Dinani
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Sabine Ambros
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Mine Ozcelik
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Ulrich Kulozik
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
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9
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Levshinskii V, Galazis C, Losev A, Zamechnik T, Kharybina T, Vesnin S, Goryanin I. Using AI and passive medical radiometry for diagnostics (MWR) of venous diseases. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 215:106611. [PMID: 34998169 DOI: 10.1016/j.cmpb.2021.106611] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 12/04/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
We studied the possibility of using artificial intelligence (AI) passive microwave radiometry (MWR) for the diagnostics of venous diseases. MWR measures non-invasive microwave emission (internal temperature) from human body 4 cm deep. The method has been used for early diagnostics in cancer, back pain, brain, COVID-19 pneumonia, and other diseases. In this paper, an AI model based on MWR data is proposed. The model was used to predict the disease state of phlebology patients. We have used MWR and infrared (skin temperature) data of the lower extremities to design a feature space and construct a classification algorithm. Our method has a sensitivity above 0.8 and a specificity above 0.7. At the same time, our method provides an advisory outcome in terms which are understandable for clinicians.
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Affiliation(s)
| | - C Galazis
- School of Informatics University of Edinburgh, Edinburgh, United Kingdom; Department of Computing, Imperial College London, London, United Kingdom
| | - A Losev
- Volgograd State University, Volgograd, Russia
| | - T Zamechnik
- Volgograd State Medical University, Volgograd, Russia
| | - T Kharybina
- Library for Natural Sciences of the Russian Academy of Sciences, Moscow, Russia
| | - S Vesnin
- Medical Microwave Radiometry Ltd, Edinburgh, United Kingdom
| | - I Goryanin
- School of Informatics University of Edinburgh, Edinburgh, United Kingdom; Institute of Theoretical and Experimental Biophysics, Moscow, Russia; Okinawa Institute of Science and Technology, Okinawa, Japan.
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10
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Verma V, Lange F, Bainbridge A, Harvey-Jones K, Robertson NJ, Tachtsidis I, Mitra S. Brain temperature monitoring in newborn infants: Current methodologies and prospects. Front Pediatr 2022; 10:1008539. [PMID: 36268041 PMCID: PMC9577084 DOI: 10.3389/fped.2022.1008539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/15/2022] [Indexed: 02/02/2023] Open
Abstract
Brain tissue temperature is a dynamic balance between heat generation from metabolism, passive loss of energy to the environment, and thermoregulatory processes such as perfusion. Perinatal brain injuries, particularly neonatal encephalopathy, and seizures, have a significant impact on the metabolic and haemodynamic state of the developing brain, and thereby likely induce changes in brain temperature. In healthy newborn brains, brain temperature is higher than the core temperature. Magnetic resonance spectroscopy (MRS) has been used as a viable, non-invasive tool to measure temperature in the newborn brain with a reported accuracy of up to 0.2 degrees Celcius and a precision of 0.3 degrees Celcius. This measurement is based on the separation of chemical shifts between the temperature-sensitive water peaks and temperature-insensitive singlet metabolite peaks. MRS thermometry requires transport to an MRI scanner and a lengthy single-point measurement. Optical monitoring, using near infrared spectroscopy (NIRS), offers an alternative which overcomes this limitation in its ability to monitor newborn brain tissue temperature continuously at the cot side in real-time. Near infrared spectroscopy uses linear temperature-dependent changes in water absorption spectra in the near infrared range to estimate the tissue temperature. This review focuses on the currently available methodologies and their viability for accurate measurement, the potential benefits of monitoring newborn brain temperature in the neonatal intensive care unit, and the important challenges that still need to be addressed.
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Affiliation(s)
- Vinita Verma
- Institute for Women's Health, University College London, London, United Kingdom
| | - Frederic Lange
- Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Alan Bainbridge
- Medical Physics and Engineering, University College London Hospital, London, United Kingdom
| | - Kelly Harvey-Jones
- Institute for Women's Health, University College London, London, United Kingdom
| | - Nicola J Robertson
- Institute for Women's Health, University College London, London, United Kingdom
| | - Ilias Tachtsidis
- Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Subhabrata Mitra
- Institute for Women's Health, University College London, London, United Kingdom
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11
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Shevelev O, Petrova M, Smolensky A, Osmonov B, Toimatov S, Kharybina T, Karbainov S, Ovchinnikov L, Vesnin S, Tarakanov A, Goryanin I. Using medical microwave radiometry for brain temperature measurements. Drug Discov Today 2021; 27:881-889. [PMID: 34767961 DOI: 10.1016/j.drudis.2021.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 09/29/2021] [Accepted: 11/02/2021] [Indexed: 11/30/2022]
Abstract
Brain temperature (BT) is a crucial physiological parameter used to monitor cerebral status. Physical activities and traumatic brain injuries (TBI) can affect BT; therefore, non-invasive BT monitoring is an important way to gain insight into TBI, stroke, and wellbeing. The effects of BT on physical performance have been studied at length. When humans are under extreme conditions, most of the energy consumed is used to maintain the BT. In addition, measuring the BT is useful for early brain diagnostics. Passive microwave radiometry (MWR) measures the intrinsic radiation of tissues in the 1-4 GHz range. It was shown that non-invasive passive MWR technology can successfully measure BT and identify even small TBIs. Here, we review the potential applications of MWR for assessing BT.
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Affiliation(s)
- Oleg Shevelev
- People' Friendship University of Russia, Moscow, Russia; Federal Research and Clinical Centre for Resuscitation and Rehabilitation, Moscow, Russia
| | - Marina Petrova
- People' Friendship University of Russia, Moscow, Russia; Federal Research and Clinical Centre for Resuscitation and Rehabilitation, Moscow, Russia
| | - Andrey Smolensky
- Russian State University of Physical Culture, Sports, Youth and Tourism, Moscow, Russia
| | - Batyr Osmonov
- Educational - Scientifc Medical Center of Kyrgyz Medical Sate University, Bishkek, Kyrgyz Republic
| | | | - Tatyana Kharybina
- Library for Natural Sciences of the Russian Academy of Sciences, Moscow, Russia
| | | | | | - Sergey Vesnin
- Medical Microwave Radiometry Ltd, Edinburgh, UK; RTM Diagnostic LLC, Moscow, Russia; Bauman Moscow State Technical University, Moscow, Russia
| | | | - Igor Goryanin
- School of Informatics, University of Edinburgh, Edinburgh, UK; Institute Theoretical and Experimental Biophysics, Pushchino, Russia; Okinawa Institute Science and Technology, Okinawa, Japan.
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12
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Design and Implementation of Multiband Noncontact Temperature-Measuring Microwave Radiometer. MICROMACHINES 2021; 12:mi12101202. [PMID: 34683253 PMCID: PMC8541249 DOI: 10.3390/mi12101202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/25/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022]
Abstract
In this paper, a multiband noncontact temperature-measuring microwave radiometer system is developed. The system can passively receive the microwave signal of the core temperature field of the human body without removing the clothes of the measured person. In order to accurately measure the actual temperature of multilayer tissue in human core temperature field, four frequency bands of 4–6 GHz, 8–12 GHz, 12–16 GHz, and 14–18 GHz were selected for multifrequency design according to the internal tissue depth model of human body and the relationship between skin depth and electromagnetic frequency. Used to measure the actual temperature of human epidermis, dermis, and subcutaneous tissue, a small and highly directional multiband angular horn antenna was designed for the radiometer front end. After the error analysis of the full-power microwave radiometer, a novel hardware architecture of the microwave interferometric temperature-measuring radiometer is proposed, and it is proven that the novel interferometric microwave radiometer has less error uncertainty through theoretical deduction. The experimental results show that the maximum detection sensitivity of the novel interferometric microwave temperature-measuring radiometer is 215 mV/dBm, and the temperature sensitivity is 0.047 K/mV. Compared with the scheme of the full-power radiometer, the detection sensitivity is increased 7.45-fold, and the temperature sensitivity is increased 13.89-fold.
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13
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Sidorov IA, Gudkov AG, Leushin VY, Gorlacheva EN, Novichikhin EP, Agasieva SV. Measurement and 3D Visualization of the Human Internal Heat Field by Means of Microwave Radiometry. SENSORS (BASEL, SWITZERLAND) 2021; 21:4005. [PMID: 34200601 PMCID: PMC8228679 DOI: 10.3390/s21124005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 11/16/2022]
Abstract
The possibility of non-invasive determination of the depth of the location and temperature of a cancer tumor in the human body by multi-frequency three-dimensional (3D) radiothermography is considered. The models describing the receiving of the human body's own radiothermal field processes are presented. The analysis of the possibility of calculating the desired parameters based on the results of measuring antenna temperatures simultaneously in two different frequency ranges is performed. Methods of displaying on the monitor screen the three-dimensional temperature distribution of the subcutaneous layer of the human body, obtained as a result of data processing of a multi-frequency multichannel radiothermograph, are considered. The possibility of more accurate localization of hyperthermia focus caused by the presence of malignant tumors in the depth of the human body with multi-frequency volumetric radiothermography is shown. The results of the study of various methods of data interpolation for displaying the continuous intrinsic radiothermal field of the human body are presented. Examples of displaying the volumetric temperature distribution by the moving plane method based on digital models and the results of an experimental study of the thermal field of the human body and head are given.
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Affiliation(s)
- Igor Alexandrovich Sidorov
- RL Research Institute, Bauman Moscow State Technical University, 105005 Moscow, Russia; (A.G.G.); (V.Y.L.); (E.N.G.)
| | - Alexsandr Grigorevich Gudkov
- RL Research Institute, Bauman Moscow State Technical University, 105005 Moscow, Russia; (A.G.G.); (V.Y.L.); (E.N.G.)
| | - Vitalij Yurievich Leushin
- RL Research Institute, Bauman Moscow State Technical University, 105005 Moscow, Russia; (A.G.G.); (V.Y.L.); (E.N.G.)
| | - Eugenia Nikolaevna Gorlacheva
- RL Research Institute, Bauman Moscow State Technical University, 105005 Moscow, Russia; (A.G.G.); (V.Y.L.); (E.N.G.)
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14
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Guido K, Bringer A, Kiourti A. Toward Non-Invasive Core Body Temperature Sensing. PROCEEDINGS. USNC-URSI RADIO SCIENCE MEETING 2021; 2021:164-165. [PMID: 33693311 PMCID: PMC7943173 DOI: 10.23919/usnc-ursinrsm51531.2021.9336477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This paper aims to explore the potential of a novel radiometry technique that leverages bio-matched antennas (BMAs), broadband measurements, and forward modeling of layered tissues for non-invasive and accurate core temperature monitoring. Our approach relies on the observation that electromagnetic waves penetrate to different depths depending on their frequency and dielectric properties of the medium and adapts radiative transfer models that have been successfully implemented in the past for layered geophysical media. Preliminary modeling and experimental results confirm feasibility.
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Affiliation(s)
- Katrina Guido
- ElectroScience Laboratory, Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA
| | - Alexandra Bringer
- ElectroScience Laboratory, Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA
| | - Asimina Kiourti
- ElectroScience Laboratory, Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA
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15
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Gudkov AG, Leushin VY, Vesnin SG, Sidorov IA, Sedankin MK, Solov’ev YV, Agasieva SV, Chizhikov SV, Gorbachev DA, Vidyakin SI. Studies of a Microwave Radiometer Based on Integrated Circuits. BIOMEDICAL ENGINEERING 2020. [DOI: 10.1007/s10527-020-09954-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Goryanin I, Karbainov S, Shevelev O, Tarakanov A, Redpath K, Vesnin S, Ivanov Y. Passive microwave radiometry in biomedical studies. Drug Discov Today 2020; 25:757-763. [PMID: 32004473 DOI: 10.1016/j.drudis.2020.01.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 12/21/2019] [Accepted: 01/22/2020] [Indexed: 01/30/2023]
Abstract
Passive microwave radiometry (MWR) measures natural emissions in the range 1-10GHz from proteins, cells, organs and the whole human body. The intensity of intrinsic emission is determined by biochemical and biophysical processes. The nature of this process is still not very well known. Infrared thermography (IRT) can detect emission several microns deep (skin temperature), whereas MWR allows detection of thermal abnormalities down to several centimeters (internal or deep temperature). MWR is noninvasive and inexpensive. It requires neither fluorescent nor radioactive labels, nor ionizing or other radiation. MWR can be used in early drug discovery as well as preclinical and clinical studies.
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Affiliation(s)
- Igor Goryanin
- University of Edinburgh, UK; Okinawa Institute Science and Technology, Okinawa, Japan; Tianjin Institute of Industrial Biotechnology, Tianjin, China.
| | | | - Oleg Shevelev
- Peoples' Friendship University of Russia, Moscow, Russia
| | | | - Keith Redpath
- Manus Neurodynamica, Edinburgh, UK; Medical Microwave Radiometry (MMWR), Edinburgh, UK
| | - Sergey Vesnin
- Medical Microwave Radiometry (MMWR), Edinburgh, UK; Bauman Moscow State Technical University (BMSTU), Moscow, Russia
| | - Yuri Ivanov
- Institute of Biomedical Chemistry (IBMC), Moscow, Russia; Joint Institute for High Temperatures of the RAS, Moscow, Russia
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Microwave Radiometry-Derived Thermal Changes of Small Joints as Additional Potential Biomarker in Rheumatoid Arthritis: A Prospective Pilot Study. J Clin Rheumatol 2019; 24:259-263. [PMID: 29652702 DOI: 10.1097/rhu.0000000000000719] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE A prospective pilot study was performed using microwave radiometry (MR), a noninvasive method detecting in-depth tissue temperature, to evaluate whether temperature-of-small-joint-derived scores correlate to parameters commonly used to assess disease activity in rheumatoid arthritis (RA). METHODS Ten patients with active, untreated RA underwent clinical and laboratory assessments and joint ultrasound and MR of hand and foot small joints at baseline and at 15, 30, and 90 days after treatment onset. Mixed-model analysis for repeated measures was used to compare patient characteristics in sequential visits. Twenty age- and sex-matched healthy individuals served as control subjects. RESULTS Using 1248 MR-derived separate recordings from patients' joints, several thermoscores involving different joint combinations were created. When compared with clinical and ultrasound data, the best performing thermoscore involved temperatures of 16 joints (second to fifth metacarpal and proximal interphalangeal joints, bilaterally). This thermoscore correlated to the 28-joint Disease Activity Score-C-reactive protein, tender and swollen joint counts, patient's visual analog scale (all P ≤ 0.02), and the standard 7-joint ultrasound score (P < 0.03) and could also discriminate patients in high (mean, 9.2 [SD, 5.6]) or moderate (7.1 [SD, 3.5]) versus low disease activity/remission (4.2 [SD, 1.8]) (P ≤ 0.01) or healthy subjects (5.0 [SD, 1.7]) (P = 0.002). CONCLUSIONS Microwave radiometry-derived increased in-depth temperature indicative of local inflammation of small joints may serve as an additional biomarker in RA. Optimization of MR-based methods may result in objective assessments of RA disease activity in clinical practice.
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Groumpas E, Koutsoupidou M, Karanasiou IS, Papageorgiou C, Uzunoglu N. Real-Time Passive Brain Monitoring System Using Near-Field Microwave Radiometry. IEEE Trans Biomed Eng 2019; 67:158-165. [PMID: 30969913 DOI: 10.1109/tbme.2019.2909994] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Near-field microwave radiometry has emerged as a tool for real-time passive monitoring of local brain activation, possibly attributed to local changes in blood flow that correspond to temperature and/or conductivity changes. The aim of this study is to design and evaluate a prototype system based on microwave radiometry intended to detect local changes of temperature and conductivity in depth in brain tissues. A novel radiometric system that comprises a four port total power Dicke-switch sensitive receiver that operates at 1.5 GHz has been developed. METHODS AND RESULTS The efficacy of the system was assessed through simulation and experiment on brain tissue mimicking phantoms under different setup conditions, where temperature and conductivity changes were accurately detected. In order to validate the radiometer's capability to sense low power signals occurring spontaneously from regions in the human brain, the somatosensory cortices of one volunteer were measured under pain-inducing psychophysiological conditions. The promising results from the initial in vivo measurements prove the system's potential for more extensive investigative trials. CONCLUSION AND SIGNIFICANCE The significance of this study lies on the development of a compact and sensitive radiometer for totally passive monitoring of local brain activation as a potential complementary tool for contributing to the research effort for investigating brain functionality.
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Ivanov Y, Kozlov AF, Galiullin RA, Tatur VY, Ziborov VS, Ivanova ND, Pleshakova TO, Vesnin SG, Goryanin I. Use of Microwave Radiometry to Monitor Thermal Denaturation of Albumin. Front Physiol 2018; 9:956. [PMID: 30090068 PMCID: PMC6068392 DOI: 10.3389/fphys.2018.00956] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 06/29/2018] [Indexed: 11/25/2022] Open
Abstract
This study monitored thermal denaturation of albumin using microwave radiometry. Brightness Temperature, derived from Microwave Emission (BTME) of an aqueous solution of bovine serum albumin (0.1 mM) was monitored in the microwave frequency range 3.8–4.2 GHz during denaturation of this protein at a temperature of 56°C in a conical polypropylene cuvette. This method does not require fluorescent or radioactive labels. A microwave emission change of 1.5–2°C in the BTME of aqueous albumin solution was found during its denaturation, without a corresponding change in the water temperature. Radio thermometry makes it possible to monitor protein denaturation kinetics, and the resulting rate constant for albumin denaturation was 0.2 ± 0.1 min−1, which corresponds well to rate constants obtained by other methods.
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Affiliation(s)
- Yuri Ivanov
- Institute of Biomedical Chemistry, Moscow, Russia
| | | | | | - Vadim Y Tatur
- Foundation of Advanced Technologies and Innovations, Moscow, Russia
| | - Vadim S Ziborov
- Joint Institute for High Temperatures of Russian Academy of Sciences (RAS), Moscow, Russia
| | - Nina D Ivanova
- Moscow State Academy of Veterinary Medicine and Biotechnology, Moscow, Russia
| | | | - Sergey G Vesnin
- RES LTD, Moscow, Russia.,Medical MicroWave Radiometry (MMWR) LTD, Edinburgh, United Kingdom
| | - Igor Goryanin
- School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.,Biological Systems Unit, Okinawa Institute of Science and Technology, Okinawa, Japan.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
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20
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Anosov AA, Subochev PV, Mansfeld AD, Sharakshane AA. Physical and computer-based modeling in internal temperature reconstruction by the method of passive acoustic thermometry. ULTRASONICS 2018; 82:336-344. [PMID: 28972936 DOI: 10.1016/j.ultras.2017.09.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 06/07/2023]
Abstract
The purpose of this work was to investigate experimentally the capacity of passive acoustic thermometry (PAT) for the reconstruction of 1D, time-variable distributions of the internal temperature. Because in the PAT a noise signal is measured, a considerable integration time (about one minute) is required to attain an acceptable error level (0.5-1K). To optimize the time, an algorithm was proposed to take account of the fact that the temperature satisfied the heat equation. The problem was reduced to that of determining two parameters (initial temperature and thermal diffusivity) of the object under study. The desired parameters were considered constant and were not determined anew after each measurement; instead, their values were refined using all the previous measurements. The proposed algorithm was tested experimentally (where the temperature was reconstructed in a model object, a slab of polytetrafluoroethylene) and investigated by means of computer modeling. The duration of one measurement was about 5.5s. As a result, an error of the temperature reconstruction of about 0.5K, acceptable for medical applications, was attained after 30-60s (depending on the depth) from the beginning of the measurements. After that, temperature distributions can be reconstructed after each measurement without loss of the reconstruction accuracy. The proposed method can be used to control the temperature under a local hyperthermia, lasting 1 min and more, of the human body.
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Affiliation(s)
- A A Anosov
- Federal State Autonomous Educational Institution of Higher Education I.M. Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, 2-4 Bolshaya Pirogovskaya st., 119991 Moscow, Russia; Kotel'nikov Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Mokhovaya 11-7, Moscow 125009, Russia.
| | - P V Subochev
- Federal Research Center, The Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul'yanov Street, 603950 Nizhny Novgorod, Russia
| | - A D Mansfeld
- Federal Research Center, The Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul'yanov Street, 603950 Nizhny Novgorod, Russia
| | - A A Sharakshane
- Kotel'nikov Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Mokhovaya 11-7, Moscow 125009, Russia
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Holper L, Mitra S, Bale G, Robertson N, Tachtsidis I. Prediction of brain tissue temperature using near-infrared spectroscopy. NEUROPHOTONICS 2017; 4:021106. [PMID: 28630878 PMCID: PMC5469395 DOI: 10.1117/1.nph.4.2.021106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/15/2017] [Indexed: 08/17/2023]
Abstract
Broadband near-infrared spectroscopy (NIRS) can provide an endogenous indicator of tissue temperature based on the temperature dependence of the water absorption spectrum. We describe a first evaluation of the calibration and prediction of brain tissue temperature obtained during hypothermia in newborn piglets (animal dataset) and rewarming in newborn infants (human dataset) based on measured body (rectal) temperature. The calibration using partial least squares regression proved to be a reliable method to predict brain tissue temperature with respect to core body temperature in the wavelength interval of 720 to 880 nm with a strong mean predictive power of [Formula: see text] (animal dataset) and [Formula: see text] (human dataset). In addition, we applied regression receiver operating characteristic curves for the first time to evaluate the temperature prediction, which provided an overall mean error bias between NIRS predicted brain temperature and body temperature of [Formula: see text] (animal dataset) and [Formula: see text] (human dataset). We discuss main methodological aspects, particularly the well-known aspect of over- versus underestimation between brain and body temperature, which is relevant for potential clinical applications.
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Affiliation(s)
- Lisa Holper
- University of Zurich, Hospital of Psychiatry, Department of Psychiatry, Psychotherapy, and Psychosomatics, Zurich, Switzerland
| | - Subhabrata Mitra
- University College London and Neonatal Unit, University College London Hospitals Trust, Institute for Women’s Health, London, United Kingdom
| | - Gemma Bale
- University College London, Biomedical Optics Research Laboratory, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Nicola Robertson
- University College London and Neonatal Unit, University College London Hospitals Trust, Institute for Women’s Health, London, United Kingdom
| | - Ilias Tachtsidis
- University College London, Biomedical Optics Research Laboratory, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
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Fekete Z, Csernai M, Kocsis K, Horváth ÁC, Pongrácz A, Barthó P. Simultaneousin vivorecording of local brain temperature and electrophysiological signals with a novel neural probe. J Neural Eng 2017; 14:034001. [DOI: 10.1088/1741-2552/aa60b1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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23
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Schooneveldt G, Bakker A, Balidemaj E, Chopra R, Crezee J, Geijsen ED, Hartmann J, Hulshof MC, Kok HP, Paulides MM, Sousa-Escandon A, Stauffer PR, Maccarini PF. Thermal dosimetry for bladder hyperthermia treatment. An overview. Int J Hyperthermia 2016; 32:417-33. [DOI: 10.3109/02656736.2016.1156170] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Rodrigues DB, Stauffer PR, Colebeck E, Hood AZ, Salahi S, Maccarini PF, Topsakal E. Dielectric properties measurements of brown and white adipose tissue in rats from 0.5 to 10 GHz. Biomed Phys Eng Express 2016; 2:025005. [PMID: 29354288 PMCID: PMC5773071 DOI: 10.1088/2057-1976/2/2/025005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Brown adipose tissue (BAT) plays an important role in whole body metabolism and with appropriate stimulus could potentially mediate weight gain and insulin sensitivity. Although imaging techniques are available to detect subsurface BAT, there are currently no viable methods for continuous acquisition of BAT energy expenditure. Microwave (MW) radiometry is an emerging technology that allows the quantification of tissue temperature variations at depths of several centimeters. Such temperature differentials may be correlated with variations in metabolic rate, thus providing a quantitative approach to monitor BAT metabolism. In order to optimize MW radiometry, numerical and experimental phantoms with accurate dielectric properties are required to develop and calibrate radiometric sensors. Thus, we present for the first time, the characterization of relative permittivity and electrical conductivity of brown (BAT) and white (WAT) adipose tissues in rats across the MW range 0.5-10GHz. Measurements were carried out in situ and post mortem in six female rats of approximately 200g. A Cole-Cole model was used to fit the experimental data into a parametric model that describes the variation of dielectric properties as a function of frequency. Measurements confirm that the dielectric properties of BAT (εr = 14.0-19.4, σ = 0.3-3.3S/m) are significantly higher than those of WAT (εr = 9.1-11.9, σ = 0.1-1.9S/m), in accordance with the higher water content of BAT.
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Affiliation(s)
- D B Rodrigues
- Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - P R Stauffer
- Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - E Colebeck
- Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762, USA
| | - A Z Hood
- Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762, USA
| | | | - P F Maccarini
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - E Topsakal
- Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762, USA
- Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
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Atallah L, Bongers E, Lamichhane B, Bambang-Oetomo S. Unobtrusive Monitoring of Neonatal Brain Temperature Using a Zero-Heat-Flux Sensor Matrix. IEEE J Biomed Health Inform 2014; 20:100-7. [PMID: 25546867 DOI: 10.1109/jbhi.2014.2385103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The temperature of preterm neonates must be maintained within a narrow window to ensure their survival. Continuously measuring their core temperature provides an optimal means of monitoring their thermoregulation and their response to environmental changes. However, existing methods of measuring core temperature can be very obtrusive, such as rectal probes, or inaccurate/lagging, such as skin temperature sensors and spot-checks using tympanic temperature sensors. This study investigates an unobtrusive method of measuring brain temperature continuously using an embedded zero-heat-flux (ZHF) sensor matrix placed under the head of the neonate. The measured temperature profile is used to segment areas of motion and incorrect positioning, where the neonate's head is not above the sensors. We compare our measurements during low motion/stable periods to esophageal temperatures for 12 preterm neonates, measured for an average of 5 h per neonate. The method we propose shows good correlation with the reference temperature for most of the neonates. The unobtrusive embedding of the matrix in the neonate's environment poses no harm or disturbance to the care work-flow, while measuring core temperature. To address the effect of motion on the ZHF measurements in the current embodiment, we recommend a more ergonomic embedding ensuring the sensors are continuously placed under the neonate's head.
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Stauffer PR, Snow BW, Rodrigues DB, Salahi S, Oliveira TR, Reudink D, Maccarini PF. Non-invasive measurement of brain temperature with microwave radiometry: demonstration in a head phantom and clinical case. Neuroradiol J 2014; 27:3-12. [PMID: 24571829 DOI: 10.15274/nrj-2014-10001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Accepted: 12/14/2013] [Indexed: 12/27/2022] Open
Abstract
This study characterizes the sensitivity and accuracy of a non-invasive microwave radiometric thermometer intended for monitoring body core temperature directly in brain to assist rapid recovery from hypothermia such as occurs during surgical procedures. To study this approach, a human head model was constructed with separate brain and scalp regions consisting of tissue equivalent liquids circulating at independent temperatures on either side of intact skull. This test setup provided differential surface/deep tissue temperatures for quantifying sensitivity to change in brain temperature independent of scalp and surrounding environment. A single band radiometer was calibrated and tested in a multilayer model of the human head with differential scalp and brain temperature. Following calibration of a 500MHz bandwidth microwave radiometer in the head model, feasibility of clinical monitoring was assessed in a pediatric patient during a 2-hour surgery. The results of phantom testing showed that calculated radiometric equivalent brain temperature agreed within 0.4°C of measured temperature when the brain phantom was lowered 10°C and returned to original temperature (37°C), while scalp was maintained constant over a 4.6-hour experiment. The intended clinical use of this system was demonstrated by monitoring brain temperature during surgery of a pediatric patient. Over the 2-hour surgery, the radiometrically measured brain temperature tracked within 1-2°C of rectal and nasopharynx temperatures, except during rapid cooldown and heatup periods when brain temperature deviated 2-4°C from slower responding core temperature surrogates. In summary, the radiometer demonstrated long term stability, accuracy and sensitivity sufficient for clinical monitoring of deep brain temperature during surgery.
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Affiliation(s)
- Paul R Stauffer
- Departments of Radiation Oncology and Biomedical Engineering, Duke University; Durham, NC, USA - Department of Radiation Oncology, Thomas Jefferson University; Philadelphia PA, USA -
| | - Brent W Snow
- Department of Surgery and Urology, University of Utah; Salt Lake City, UT, USA - Thermimage Inc.; Salt Lake City, UT, USA
| | - Dario B Rodrigues
- Departments of Radiation Oncology and Biomedical Engineering, Duke University; Durham, NC, USA - CEFITEC, FCT, New University of Lisbon; Caparica, Portugal
| | - Sara Salahi
- Departments of Radiation Oncology and Biomedical Engineering, Duke University; Durham, NC, USA - ANSYS, Inc.; Irvine, CA, USA
| | - Tiago R Oliveira
- Departments of Radiation Oncology and Biomedical Engineering, Duke University; Durham, NC, USA - Institute of Physics, University of São Paulo; São Paulo, Brazil
| | | | - Paolo F Maccarini
- Departments of Radiation Oncology and Biomedical Engineering, Duke University; Durham, NC, USA
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27
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Kok HP, Gellermann J, van den Berg CAT, Stauffer PR, Hand JW, Crezee J. Thermal modelling using discrete vasculature for thermal therapy: A review. Int J Hyperthermia 2013; 29:336-45. [PMID: 23738700 DOI: 10.3109/02656736.2013.801521] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Reliable temperature information during clinical hyperthermia and thermal ablation is essential for adequate treatment control, but conventional temperature measurements do not provide 3D temperature information. Treatment planning is a very useful tool to improve treatment quality, and substantial progress has been made over the last decade. Thermal modelling is a very important and challenging aspect of hyperthermia treatment planning. Various thermal models have been developed for this purpose, with varying complexity. Since blood perfusion is such an important factor in thermal redistribution of energy in in vivo tissue, thermal simulations are most accurately performed by modelling discrete vasculature. This review describes the progress in thermal modelling with discrete vasculature for the purpose of hyperthermia treatment planning and thermal ablation. There has been significant progress in thermal modelling with discrete vasculature. Recent developments have made real-time simulations possible, which can provide feedback during treatment for improved therapy. Future clinical application of thermal modelling with discrete vasculature in hyperthermia treatment planning is expected to further improve treatment quality.
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Affiliation(s)
- H Petra Kok
- Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, The Netherlands.
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Rodrigues DB, Maccarini PF, Salahi S, Colebeck E, Topsakal E, Pereira PJS, Limão-Vieira P, Stauffer PR. Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of brown fat metabolism. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2013; 8584:10.1117/12.2004931. [PMID: 24244831 PMCID: PMC3824263 DOI: 10.1117/12.2004931] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. METHODS A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. RESULTS The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. CONCLUSIONS Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5 °C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism.
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Affiliation(s)
- Dario B. Rodrigues
- Department of Radiation Oncology, Hyperthermia Division, PO BOX 3085 Duke University Medical Center, Durham, NC 27710, USA
- CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Paolo F. Maccarini
- Department of Radiation Oncology, Hyperthermia Division, PO BOX 3085 Duke University Medical Center, Durham, NC 27710, USA
| | | | - Erin Colebeck
- Department of Electrical and Computer Engineering, Mississippi State University, Mississippi State, MS 39762, USA
| | - Erdem Topsakal
- Department of Electrical and Computer Engineering, Mississippi State University, Mississippi State, MS 39762, USA
| | - Pedro J. S. Pereira
- CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
- Departament of Mathematics, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal
| | - Paulo Limão-Vieira
- CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Paul R. Stauffer
- Department of Radiation Oncology, Hyperthermia Division, PO BOX 3085 Duke University Medical Center, Durham, NC 27710, USA
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Klemetsen Ø, Jacobsen S, Birkelund Y. Radiometric temperature reading of a hot ellipsoidal object inside the oral cavity by a shielded microwave antenna put flush to the cheek. Phys Med Biol 2012; 57:2633-52. [PMID: 22504068 DOI: 10.1088/0031-9155/57/9/2633] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new scheme for detection of vesicoureteral reflux (VUR) in children has recently been proposed in the literature. The idea is to warm bladder urine via microwave exposure to at least fever temperatures and observe potential urine reflux from the bladder back to the kidney(s) by medical radiometry. As a preliminary step toward realization of this detection device, we present non-invasive temperature monitoring by use of microwave radiometry in adults to observe temperature dynamics in vivo of a water-filled balloon placed within the oral cavity. The relevance of the approach with respect to detection of VUR in children is motivated by comparing the oral cavity and cheek tissue with axial CT images of young children in the bladder region. Both anatomical locations reveal a triple-layered tissue structure consisting of skin-fat-muscle with a total thickness of about 8-10 mm. In order to mimic variations in urine temperature, the target balloon was flushed with water coupled to a heat exchanger, that was moved between water baths of different temperatures, to induce measurable temperature gradients. The applied radiometer has a center frequency of 3.5 GHz and provides a sensitivity (accuracy) of 0.03 °C for a data acquisition time of 2 s. Three different scenarios were tested and included observation through the cheek tissue with and without an intervening water bolus compartment present. In all cases, radiometric readings observed over a time span of 900 s were shown to be highly correlated (R ~ 0.93) with in situ temperatures obtained by fiberoptic probes.
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Affiliation(s)
- Øystein Klemetsen
- Faculty of Science, Department of Physics and Technology, University of Tromsø, Tromsø, Norway.
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Birkelund Y, Klemetsen Ø, Jacobsen SK, Arunachalam K, Maccarini P, Stauffer PR. Vesicoureteral reflux in children: a phantom study of microwave heating and radiometric thermometry of pediatric bladder. IEEE Trans Biomed Eng 2011; 58:3269-78. [PMID: 21900069 DOI: 10.1109/tbme.2011.2167148] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for noninvasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2-D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 s with 20 Watts power for heating, and 10 s without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder.
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Affiliation(s)
- Yngve Birkelund
- Department of Physics and Technology, University of Tromsø, Tromsø, Norway.
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31
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Arunachalam K, Maccarini P, De Luca V, Tognolatti P, Bardati F, Snow B, Stauffer P. Detection of vesicoureteral reflux using microwave radiometry-system characterization with tissue phantoms. IEEE Trans Biomed Eng 2011; 58:1629-36. [PMID: 21257366 DOI: 10.1109/tbme.2011.2107515] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Microwave (MW) radiometry is proposed for passive monitoring of kidney temperature to detect vesicoureteral reflux (VUR) of urine that is externally heated by a MW hyperthermia device and thereafter reflows from the bladder to kidneys during reflux. Here, we characterize in tissue-mimicking phantoms the performance of a 1.375 GHz radiometry system connected to an electromagnetically (EM) shielded microstrip log spiral antenna optimized for VUR detection. Phantom EM properties are characterized using a coaxial dielectric probe and network analyzer (NA). Power reflection and receive patterns of the antenna are measured in layered tissue phantom. Receiver spectral measurements are used to assess EM shielding provided by a metal cup surrounding the antenna. Radiometer and fiberoptic temperature data are recorded for varying volumes (10-30 mL) and temperaturesg (40-46°C) of the urine phantom at 35 mm depth surrounded by 36.5°C muscle phantom. Directional receive pattern with about 5% power spectral density at 35 mm target depth and better than -10 dB return loss from tissue load are measured for the antenna. Antenna measurements demonstrate no deterioration in power reception and effective EM shielding in the presence of the metal cup. Radiometry power measurements are in excellent agreement with the temperature of the kidney phantom. Laboratory testing of the radiometry system in temperature-controlled phantoms supports the feasibility of passive kidney thermometry for VUR detection.
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Abstract
AIM Therapeutic hypothermia after perinatal asphyxia decreases brain injury in newborns, whereas hyperthermia worsens the brain injury. We examined how different clinical practices influence regional brain temperatures during hypothermia. METHODS Six newborn pigs, which have comparable physiology and brain maturation to human term infants, were maintained at hypothermia (33.5°C) or normothermia with a servo-controlled whole-body cooling device that is in clinical use. Pigs were anesthetized and fully instrumented for cardiovascular and temperature (rectal and regional brain) monitoring. Changes in brain temperatures were measured during four different paradigms to mimic different clinical practices. RESULTS Inserting an insulating pillow between the head and the heated surface reduced cortex temperature by 1 or 2°C during normothermia (core temperature T(core) 37°C) or hypothermia, T(core) 33.5°C. Reducing ambient temperature from 28°C to 23°C reduced cortex temperature by 3.9 ± 1.9°C. Without a hat and overhead heater at normothermia, cortex and deep brain temperatures were reduced by 1.2 ± 0.8 and 0.7 ± 0.7°C, respectively. Direct overhead heating abolished the normal cortex to deep brain temperature gradient that was maintained if using a head shield. CONCLUSION Brain temperature may differ from core temperature during therapeutic hypothermia influenced by different clinical practices.
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Stauffer PR, Maccarini P, Arunachalam K, Craciunescu O, Diederich C, Juang T, Rossetto F, Schlorff J, Milligan A, Hsu J, Sneed P, Vujaskovic Z. Conformal microwave array (CMA) applicators for hyperthermia of diffuse chest wall recurrence. Int J Hyperthermia 2010; 26:686-98. [PMID: 20849262 DOI: 10.3109/02656736.2010.501511] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE This article summarises the evolution of microwave array applicators for heating large area chest wall disease as an adjuvant to external beam radiation, systemic chemotherapy, and potentially simultaneous brachytherapy. METHODS Current devices used for thermotherapy of chest wall recurrence are reviewed. The largest conformal array applicator to date is evaluated in four studies: (1) ability to conform to the torso is demonstrated with a CT scan of a torso phantom and MR scan of the conformal water bolus component on a mastectomy patient; (2) specific absorption rate (SAR) and temperature distributions are calculated with electromagnetic and thermal simulation software for a mastectomy patient; (3) SAR patterns are measured with a scanning SAR probe in liquid muscle phantom for a buried coplanar waveguide CMA; and (4) heating patterns and patient tolerance of CMA applicators are characterised in a clinical pilot study with 13 patients. RESULTS CT and MR scans demonstrate excellent conformity of CMA applicators to contoured anatomy. Simulations demonstrate effective control of heating over contoured anatomy. Measurements confirm effective coverage of large treatment areas with no gaps. In 42 hyperthermia treatments, CMA applicators provided well-tolerated effective heating of up to 500 cm(2) regions, achieving target temperatures of T(min) = 41.4 ± 0.7°C, T(90) = 42.1 ± 0.6°C, T(ave) = 42.8 ± 0.6°C, and T(max) = 44.3 ± 0.8°C as measured in an average of 90 points per treatment. CONCLUSION The CMA applicator is an effective thermal therapy device for heating large-area superficial disease such as diffuse chest wall recurrence. It is able to cover over three times the treatment area of conventional hyperthermia devices while conforming to typical body contours.
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Affiliation(s)
- Paul R Stauffer
- Radiation Oncology Department, Duke University, Durham, NC 27710, USA.
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Li Z, Vogel M, Maccarini PF, Stakhursky V, Soher BJ, Craciunescu OI, Das S, Arabe OA, Joines WT, Stauffer PR. Improved hyperthermia treatment control using SAR/temperature simulation and PRFS magnetic resonance thermal imaging. Int J Hyperthermia 2010; 27:86-99. [PMID: 21070140 DOI: 10.3109/02656736.2010.501509] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
PURPOSE This article explores the feasibility of using coupled electromagnetic and thermodynamic simulations to improve planning and control of hyperthermia treatments for cancer. The study investigates the usefulness of preplanning to improve heat localisation in tumour targets in treatments monitored with PRFS-based magnetic resonance thermal imaging (MRTI). METHODS Heating capabilities of a cylindrical radiofrequency (RF) mini-annular phased array (MAPA) applicator were investigated with electromagnetic and thermal simulations of SAR in homogeneous phantom models and two human leg sarcomas. High frequency structure simulator (HFSS) (Ansoft) was used for electromagnetic simulations and SAR patterns were coupled into EPhysics (Ansoft) for thermal modelling with temperature-dependent variable perfusion. Simulations were accelerated by integrating tumour-specific anatomy into a pre-gridded whole body tissue model. To validate this treatment planning approach, simulations were compared with MR thermal images in both homogenous phantoms and heterogeneous tumours. RESULTS SAR simulations demonstrated excellent agreement with temperature rise distributions obtained with MR thermal imaging in homogeneous phantoms and clinical treatments of large soft-tissue sarcomas. The results demonstrate feasibility of preplanning appropriate relative phases of antennas for localising heat in tumour. CONCLUSIONS Advances in the accuracy of computer simulation and non-invasive thermometry via MR thermal imaging have provided powerful new tools for optimisation of clinical hyperthermia treatments. Simulations agree well with MR thermal images in both homogeneous tissue models and patients with lower leg tumours. This work demonstrates that better quality hyperthermia treatments should be possible when simplified hybrid model simulations are performed routinely as part of the clinical pretreatment plan.
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Affiliation(s)
- Zhen Li
- Department of Electric and Computer Engineering, School of Engineering
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35
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Arunachalam K, Maccarini PF, De Luca V, Bardati F, Snow BW, Stauffer PR. Modeling the detectability of vesicoureteral reflux using microwave radiometry. Phys Med Biol 2010; 55:5417-35. [PMID: 20736499 PMCID: PMC2972589 DOI: 10.1088/0031-9155/55/18/010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We present the modeling efforts on antenna design, frequency selection and receiver sensitivity estimation to detect vesicoureteral reflux (VUR) using microwave (MW) radiometry as warm urine from the bladder maintained at fever range temperature using a MW hyperthermia device reflows into the kidneys. The radiometer center frequency (f(c)), frequency band (Deltaf) and aperture radius (r(a)) of the physical antenna for kidney temperature monitoring are determined using a simplified universal antenna model with a circular aperture. Anatomical information extracted from the computed tomography (CT) images of children aged 4-6 years is used to construct a layered 3D tissue model. Radiometric antenna efficiency is evaluated in terms of the ratio of the power collected from the target at depth to the total power received by the antenna (eta). The power ratio of the theoretical antenna is used to design a microstrip log spiral antenna with directional radiation pattern over f(c) +/- Deltaf/2. Power received by the log spiral from the deep target is enhanced using a thin low-loss dielectric matching layer. A cylindrical metal cup is proposed to shield the antenna from electromagnetic interference (EMI). Transient thermal simulations are carried out to determine the minimum detectable change in the antenna brightness temperature (deltaT(B)) for 15-25 mL urine refluxes at 40-42 degrees C located 35 mm from the skin surface. Theoretical antenna simulations indicate maximum eta over 1.1-1.6 GHz for r(a) = 30-40 mm. Simulations of the 35 mm radius tapered log spiral yielded a higher power ratio over f(c) +/- Deltaf/2 for the 35-40 mm deep targets in the presence of an optimal matching layer. Radiometric temperature calculations indicate deltaT(B) 0.1 K for the 15 mL urine at 40 degrees C and 35 mm depth. Higher eta and deltaT(B) were observed for the antenna and matching layer inside the metal cup. Reflection measurements of the log spiral in a saline phantom are in agreement with the simulation data. The numerical study suggests that a radiometer with f(c) = 1.35 GHz, Deltaf = 500 MHz and detector sensitivity better than 0.1 K would be the appropriate tool to noninvasively detect VUR using the log spiral antenna.
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Affiliation(s)
- Kavitha Arunachalam
- Department of Engineering Design, Indian Institute of Technology Madras, Chennai, India.
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36
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Jacobsen S, Klemetsen Ø. Improved detectability in medical microwave radio-thermometers as obtained by active antennas. IEEE Trans Biomed Eng 2009; 55:2778-85. [PMID: 19126458 DOI: 10.1109/tbme.2008.2002156] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microwave radiometry is a spectral measurement technique for resolving blackbody radiation of heated matter above absolute zero. The emission levels vary with frequency and are at body temperatures maximized in the infrared spectral band. Medical radio-thermometers are mostly noninvasive short-range instruments that can provide temperature distributions in subcutaneous biological tissues when operated in the microwave region. However, a crucial limitation of the microwave radiometric observation principle is the extremely weak signal level of the thermal noise emitted by the lossy material (-174 dBm/Hz at normal body temperature). To improve the radiometer SNR, we propose to integrate a tiny, moderate gain, low-noise preamplifier (LNA) close to the antenna terminals as to obtain increased detectability of deep seated thermal gradients within the volume under investigation. The concept is verified experimentally in a lossy phantom medium by scanning an active antenna across a thermostatically controlled water phantom with a hot object embedded at 38 mm depth. Three different setups were investigated with decreasing temperature contrasts between the target and ambient medium. As a direct consequence of less ripple on the raw radiometric signal, statistical analysis shows a marked increase in signal-to-clutter ratio of the brightness temperature spatial scan profiles, when comparing active antenna operation with conventional passive setups.
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Affiliation(s)
- Svein Jacobsen
- Department of Physics and Technology, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway.
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Hand JW. Modelling the interaction of electromagnetic fields (10 MHz–10 GHz) with the human body: methods and applications. Phys Med Biol 2008; 53:R243-86. [DOI: 10.1088/0031-9155/53/16/r01] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Arunachalam K, Stauffer PR, Maccarini PF, Jacobsen S, Sterzer F. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load. Phys Med Biol 2008; 53:3883-901. [PMID: 18591733 DOI: 10.1088/0031-9155/53/14/011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 degrees C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 degrees C resolution and standard deviation of 0.217 degrees C for homogeneous and layered tissue loads at temperatures between 32-45 degrees C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators.
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Affiliation(s)
- K Arunachalam
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
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Sugiura T, Kouno Y, Hashizume A, Hirata H, Hand JW, Okita Y, Mizushina S. Five-band microwave radiometer system for non-invasive measurement of brain temperature in new-born infants: system calibration and its feasibility. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:2292-5. [PMID: 17272186 DOI: 10.1109/iembs.2004.1403666] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Recent simulation studies have shown that a technique of multi-frequency microwave radiometry is feasible for non-invasive measurement of deep brain temperatures in the new-born infants. A five-band microwave radiometer system has been developed, and its operation in a normal electromagnetic environment is checked. Five receivers operating with a waveguide antenna and at center frequencies of 1.2, 1.65, 2.3, 3.0 and 3.6 GHz (0.4 GHz bandwidth) are calibrated using a temperature-controlled water-bath. Temperature resolutions obtained for each receiver are 0.183, 0.273, 0.148, 0.108 and 0.118 K, respectively. A temperature retrieval simulation based on these resolutions and the previously proposed algorithm shows that the confidence interval, as produced by thermal noise, is 0.62 K for the retrieved central brain temperature. If the conductivity of brain is estimated wrong by 10 %, this will result in an error of 0.3-0.4 K. The result of this work is encouraging for realization of radiometric measurement of temperature profile in a baby's head.
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Affiliation(s)
- T Sugiura
- Research Institute of Electronics, Shizuoka University, Hamamatsu, Japan
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40
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Jacobsen S, Stauffer PR. Can we settle with single-band radiometric temperature monitoring during hyperthermia treatment of chestwall recurrence of breast cancer using a dual-mode transceiving applicator? Phys Med Biol 2007; 52:911-28. [PMID: 17264361 DOI: 10.1088/0031-9155/52/4/004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The total thermal dose that can be delivered during hyperthermia treatments is frequently limited by temperature heterogeneities in the heated tissue volume. Reliable temperature information on the heated area is thus vital for the optimization of clinical dosimetry. Microwave radiometry has been proposed as an accurate, quick and painless temperature sensing technique for biological tissue. Advantages include the ability to sense volume-averaged temperatures from subsurface tissue non-invasively, rather than with a limited set of point measurements typical of implanted temperature probes. We present a procedure to estimate the maximum tissue temperature from a single radiometric brightness temperature which is based on a numerical simulation of 3D tissue temperature distributions induced by microwave heating at 915 MHz. The temperature retrieval scheme is evaluated against errors arising from unknown variations in thermal, electromagnetic and design model parameters. Whereas realistic deviations from base values of dielectric and thermal parameters have only marginal impact on performance, pronounced deviations in estimated maximum tissue temperature are observed for unanticipated variations of the temperature or thickness of the bolus compartment. The need to pay particular attention to these latter applicator construction parameters in future clinical implementation of the thermometric method is emphasized.
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Affiliation(s)
- Svein Jacobsen
- Electrical Engineering Group, Department of Physics and Technology, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway.
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Brajkovic D, Ducharme MB. Confounding factors in the use of the zero-heat-flow method for non-invasive muscle temperature measurement. Eur J Appl Physiol 2005; 94:386-91. [PMID: 15864635 DOI: 10.1007/s00421-005-1336-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2005] [Indexed: 10/25/2022]
Abstract
This study evaluated a zero-heat-flow (ZHF), non-invasive temperature probe for in- vivo measurement of resting muscle temperature for up to 2 cm below the skin surface. The ZHF probe works by preventing heat loss from the tissue below the probe by actively heating the tissue until no temperature gradient exists across the probe. The skin temperature under the probe is then used as an indicator of the muscle temperature below. Eight subjects sat for 130 min during exposure to 28 degrees C air. Vastus lateralis (lateral thigh) muscle temperature was measured non-invasively using a ZHF probe which covered an invasive multicouple probe (which measured tissue temperature 0.5 cm, 1 cm, 1.5 cm, and 2 cm below the skin) located 15 cm superior to the patella (T (covered)). T (covered) was evaluated against an uncovered control multicouple probe located 20 cm superior to the patella (T (uncovered)). Rectal temperature and lateral thigh skin temperature were also measured. Mean T (uncovered) (based on average temperatures at the 0.5 cm, 1 cm, 1.5 cm, and 2 cm depths) and Mean T (covered) were similar from time 0 min to 60 min. However, when the ZHF was turned on at 70 min, Mean T (covered) increased by 2.11 +/- 0.20 degrees C by 130 min, while T (uncovered) remained stable. The ZHF probe temperature was similar to T (covered) at 1 cm and after time 85 min, significantly higher than T (covered) at the 0.5 cm, 1.5 cm, and 2 cm depths; however from a physiological standpoint, the temperatures between the different depths and the ZHF probe could be considered uniform (< or =0.2 degrees C separation). Rectal and thigh skin temperatures were stable at 36.99 +/- 0.08 degrees C and 32.82 +/- 0.23 degrees C, respectively. In conclusion, the non-invasive ZHF probe temperature was similar to the T (covered) temperatures directly measured up to 2 cm beneath the surface of the thigh, but all T (covered) temperatures were not representative of the true muscle temperature up to 2 cm below the skin because the ZHF probe heated the muscle by 2.11 +/- 0.20 degrees C during its operation.
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Affiliation(s)
- Dragan Brajkovic
- Defence Research and Development Canada - Toronto, Human Protection and Performance Group, Toronto, ON, Canada.
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42
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Jacobsen S, Rolfsnes HO, Stauffer PR. Characteristics of Microstrip Muscle-Loaded Single-Arm Archimedean Spiral Antennas as Investigated by FDTD Numerical Computations. IEEE Trans Biomed Eng 2005; 52:321-30. [PMID: 15709670 DOI: 10.1109/tbme.2004.840502] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The radiation characteristics and mode of operation of single-arm, groundplane backed, Archimedean spiral antennas are investigated by means of conformal finite difference time domain numerical analysis. It is shown that this antenna type may be categorized as a well-matched, broadband, circularly polarized traveling wave structure that can be fed directly by nonbalanced coaxial networks. The study further concentrates on relevant design and description features parameterized in terms of measures like radiation efficiency, sensing depth, directivity, and axial ratio of complementary polarizations. We document that an antenna of only 30-mm transverse size produces circularly polarized waves in a two-octave frequency span (2-8 GHz) with acceptable radiation efficiency (76%-94%) when loaded by muscle-like tissue.
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Affiliation(s)
- Svein Jacobsen
- Electrical Engineering Group, Institute of Physics, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway.
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