| 1. |
- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Numerical Evaluation of Clinical Applicator for Microwave Hyperthermia Treatment of Head & Neck Tumors
- 2013
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Ingår i: 7th European Conference on Antennas and Propagation.
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Konferensbidrag (refereegranskat)abstract
- Design, analysis and evaluation of a novel antenna applicator for microwave hyperthermia. The self-grounded Bow-Tie antenna immersed in cylindrical water bolus serves as an array element. The applicator consists of 12 to 18 elementsarranged in one to three ring set-ups and operates at frequency range between 400 and 1000 MHz.
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| 2. |
- Dobsicek Trefna, Hana, 1979, et al.
(författare)
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Antenna Applicator for Microwave Hyperthermia Treatment of Pediatric Brain Cancer
- 2014
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Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014, The Hague, The Netherlands 6-11 April 2014. - 9788890701849
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A novel antenna applicator for microwave hyperthermia allowing treatment of deep brain tumors is proposed. The applicator consists of up to 16 antennas placed around the head in a helmet-like set-up and operates at a frequency range of 430-1000~MHz. The self-grounded bow-tie antennas are housed in a molded plastic enclosure with the shape of a truncated cone. The inner space of the enclosure is filled with distilled water. The antennas are attached to a perimetric water bolus with a thickness of 2 cm and aligned with the head shape. The focusing ability of the applicator was investigated on a homogeneous SAM model and on a model of a 13-year old patient containing a spherical tumor of 2 cm radius. Two different tumor positions were investigated: the right frontal lobe and the central brain. The obtained SAR distributions are favorable, although a relatively high level of energy is also absorbed on the surface of the body. This heating is however not expected to cause problems as it can be cooled by blood perfusion and water bolus. Our results show that focused microwave heating in the brain is feasible and warrants further verification on phantoms.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Fhager, Andreas, 1976, et al.
(författare)
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Microwave Technology in Medical Diagnostics and Treatment
- 2015
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Ingår i: 2015 Ieee Mtt-S International Microwave Workshop Series on Rf and Wireless Technologies for Biomedical and Healthcare Applications. - New York : Ieee. - 9781479985432 ; , s. 133-134
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- There is a great need for novel diagnostics and treatment tools in today's healthcare. In this paper we describe our development and progress in novel microwave based diagnostics and treatment applications. The target applications are stroke diagnostics, breast cancer detection and microwave hyperthermia.
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| 7. |
- Maaskant, Rob, 1978, et al.
(författare)
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Fast analysis of gap waveguides using the characteristic basis function method and the parallel-plate Green’s function
- 2012
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Ingår i: 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA), Cape Town, WP, South Africa, 2-8 Sept 2012. - 9781467303354 ; , s. 788-791
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Konferensbidrag (refereegranskat)abstract
- The Characteristic Basis Function Method is employed in conjunction with the parallel-plate dyadic Green's function method to obtain the impedance characteristics of electrically large gap-waveguide structures. Numerical results are shown for the groove gap waveguide demonstrating reduced execution times relative to the HFSS software, while the solution accuracy is barely compromised.
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| 8. |
- Persson, Mikael, 1959, et al.
(författare)
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Microwave based diagnostics and treatment in practice
- 2013
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Ingår i: 2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2013 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Globally, around 15 million people each year suffer a stroke. Only a small fraction of stroke patients who could benefit from thrombolytic treatment reach diagnosis and treatment in time. To increase this low figure we have developed microwave technology aiming to differentiate hemorrhagic from ischemic stroke patients. The standard method for breast cancer diagnosis today is X-ray mammography. Despite its recognized ability to detect tumors it suffers from some limitations. Neither the false positive nor the false negative detection rates are negligible. An interesting alternative being researched extensively today is microwave tomography. In our current strive to develop a clinical prototype we have found that the most suitable design consists of an antenna array placed in a full 3D pattern. During the last decade clinical studies have demonstrated the ability of microwave hyperthermia to dramatically enhance cancer patient survival. The fundamental challenge is to adequately heat deep-seated tumors while preventing surrounding healthy tissue from undesired heating and damage. We are specifically addressing the challenge to deliver power levels with spatial control, patient treatment planning, and noninvasive temperature measurements. © 2013 IEEE.
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| 9. |
- Takook, Pegah, 1982, et al.
(författare)
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3-D time-reversal method in microwave hyperthermia
- 2014
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Ingår i: 29th Annual Meeting, European Society for Hyperthermia Onchology (ESHO), June 2014, Torino, Italy.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we present a 3-D time-reversal focusing technique for hyperthermia treatment of deep seated tumors. This method which was previously presented in 2-D1, is fast and applicable to continuous and pulsed waves. The aim is to introduce the 3-D time-reversal treatment planning and to compare it with the 2-D case in terms of their corresponding performance indicators computed in a tongue tumor.
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| 10. |
- Takook, Pegah, 1982, et al.
(författare)
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A compact wideband antenna for deep hyperthermia applicator
- 2013
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Ingår i: 28th Annual Meeting, European Society for Hyperthermia Onchology (ESHO), June 2013, Munich, Germany.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we present a compact, wideband antenna to be used in an antenna applicator. This applicator is developed for microwave hyperthermia of deep seated tumours in head and neck. The antenna should be of small size, with wide frequency band and directive radiation pattern. The desired wide bandwidth of 0.4 to 0.9 GHz, is due to multiple frequency approach in our treatment strategy.
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| 11. |
- Takook, Pegah, 1982, et al.
(författare)
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A compact wideband antenna for microwave hyperthermia system
- 2013
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Ingår i: Medicinteknikdagarna,Stockholm,2013. ; , s. 15-
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Konferensbidrag (refereegranskat)abstract
- Hyperthermia treatment is a medical treatment during which the temperature is raised in tumours for a sufficient period oftime, to kill the cancer cells or make them more sensitive to ionizing radiation or chemotherapy.Different type of antennas have been used so far in deep hyperthermia applicators, such as water-filled waveguide antennas,dipole antennas or probe-fed patch antennas. These antennas are either large and heavy (like as the waveguide antennas) orpresent very narrow bandwidth which are not desired characteristics.In this paper we present a compact, wideband antenna to be used in hyperthermia antenna applicator. This applicator isdeveloped for microwave hyperthermia of deep seated tumours in head and neck.The antenna should be of small size, with wide frequency band and directive radiation pattern. The desired wide bandwidthof 0.4 to 0.9 GHz, is due to multiple frequency approach in our treatment strategy.
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| 12. |
- Takook, Pegah, 1982, et al.
(författare)
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A computational study using time reversal focusing for hyperthermia treatment planning
- 2017
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Ingår i: Progress in Electromagnetics Research B. - 1937-6472. ; 73:1, s. 117-130
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Tidskriftsartikel (refereegranskat)abstract
- In hyperthermia treatment planning (HTP) the goal is to find the amplitudes and phases of antennas in the applicator to efficiently heat the tumor. To do this prior information regarding tumor characteristics such as the size, position and geometry, in addition to an exact model of the hyperthermia applicator is needed. Based on this information, the optimal frequency of operation can be determined. In this paper the optimum frequency for hyperthermia treatment based on the tumor and applicator characteristics, using time reversal as the focusing technique, is studied. As prior information, we consider tumor size and position, the number of the antennas in the applicator and the frequency characteristics. The obtained optimal frequency range is found using hyperthermia quality indicator values calculated from simulations. We also determine the optimum position of the virtual source in the initial step of the time reversal method to increase the quality of the treatment.
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| 13. |
- Takook, Pegah, 1982, et al.
(författare)
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Compact self-grounded Bow-Tie antenna design for an UWB phased-array hyperthermia applicator
- 2017
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Ingår i: International Journal of Hyperthermia. - : Informa UK Limited. - 0265-6736 .- 1464-5157. ; 33:4, s. 387-400
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Tidskriftsartikel (refereegranskat)abstract
- Using UWB hyperthermia systems has the potential to improve the heat delivery to deep seated tumours. In this paper, we present a novel self-grounded Bow–Tie antenna design which is to serve as the basis element in a phased-array applicator. The UWB operation in the frequency range of 0.43–1 GHz is achieved by immersing the antenna in a water bolus. The radiation characteristics are improved by appropriate shaping the water bolus and by inclusion of dielectric layers on the top of the radiating arms of the antenna. In order to find the most appropriate design, we use a combination of performance indicators representing the most important attributes of the antenna. These are the UWB impedance matching, the transmission capability and the effective field size. The antenna was constructed and experimentally validated on muscle-like phantom. The measured reflection and transmission coefficients as well as radiation characteristics are in excellent agreement with the simulated results. MR image acquisitions with antenna located inside MR bore indicate a negligible distortion of the images by the antenna itself, which indicates MR compatibility.
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| 14. |
- Takook, Pegah, 1982, et al.
(författare)
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Comparison of parallel-plate Green’s function acceleration techniques
- 2012
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Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012, s. 1311-1315. - 9781457709180 ; , s. 1311-1315
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Konferensbidrag (refereegranskat)abstract
- A comparative study of acceleration methods for computing the infinite series summation arising in parallel-plate Green's functions is performed. The spectral summation, the application of the Shanks-transformed spatial summation, and the Ewald method are examined. Results are presented which show that, although the convergence rates of Ewald's method and the spectral summation are generally largest (i.e. less number of terms), the total series evaluation time for reaching a certain specified accuracy which is ultimately of more practical importance is shortest for the Shanks accelerated spatial summation for most of the cases we considered.
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| 15. |
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| 16. |
- Takook, Pegah, 1982, et al.
(författare)
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Evaluation of 3D Time-Reversal Focusing Method in Microwave Hyperthermia Treatment: Head and Neck Tumors
- 2015
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Ingår i: International Federation for Medical and Biological Engineering Proceedings. - Cham : Springer International Publishing. - 1680-0737. ; 48, s. 104-104
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Konferensbidrag (refereegranskat)abstract
- In this paper we present time reversal focusing techniquefor hyperthermia treatment of deep seated tumors in 3D.This method which presented for 2D case has advantages ofbeing fast and applicable to both continuous and pulsedwaves. The quantitative evaluation of performance indica-tors in hyperthermia treatment is performed on a 3D modelof head and neck, containing a tumor in tongue.
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| 17. |
- Takook, Pegah, 1982, et al.
(författare)
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Evaluation of the 3D time reversal method for hyperthermia treatment planning in head and neck tumors
- 2015
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Ingår i: 9th European Conference on Antennas and Propagation, EuCAP 2015, Lisbon, Portugal, 13-17 May 2015. - 9788890701856
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Konferensbidrag (refereegranskat)abstract
- The goal of the hyperthermia treatment is to heat up tumors to temperatures above 42°C while keeping healthy tissues at normal temperatures. To reach this goal, accurate hyperthermia treatment planning is necessary. This demands finding the optimal excitation amplitudes and phases of the antenna applicator to heat the tumor. The aim of this paper is to evaluate the 3D time reversal focusing method for hyperthermia treatment planning application. This method which is based on the constructive wave interference at the tumor site, is implemented in our code. The code makes use of finite-difference time-domain (FDTD) to solve Maxwell's equations. The effect of different parameters as the input settings of our 3D code, has been studied for optimal heating of two tumor models in a head and neck phantom. Performance indicators have been calculated to give a rough estimate of the best input settings. Based on our presented results, for laryngeal tumor with relatively small size, the computed power density in our 3D code is comparable with that obtained in the commercial software. Despite the difference between CST and 3D code results for the tongue tumor, which is mainly due to different applied antennas, the tumor coverage qualifiers for both tumors are very promising. Further improvements in the quality of treatment outcomes can be achieved by e.g. combination of different treatment plannings and hot-spot reduction techniques.
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| 18. |
- Takook, Pegah, 1982, et al.
(författare)
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Experimental evaluation of UWB applicator prototype for head and neck hyperthermia
- 2017
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Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. ; , s. 3619-3620
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Konferensbidrag (refereegranskat)abstract
- The laboratory prototype of an UWB hyperthermia applicator is presented and tested for treatment of tumors in head and neck region. The focusing ability of the presented applicator for treatment of neck tumors has been tested on a homogeneous muscle phantom at 500 MHz. Two tumor positions were investigated: one in the center and one in the side of the mid-transverse plane of the phantom. The captured temperature images show the agreement between the planned and the measured focal spots and acceptable temperature increase in these areas.
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| 19. |
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| 20. |
- Takook, Pegah, 1982
(författare)
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Optimizing microwave hyperthermia antenna systems
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents design and optimization of a microwave hyperthermia antenna system for treatment of head and neck cancer as well as brain cancer. Hyperthermia has shown the ability to enhance the performance of radiotherapy and chemotherapy in many clinical trials. The incidence of increased tissue toxicity as a result of high radiotherapy dose has made hyperthermia a safe complementing, treatment enhancing method to use in combination with radiotherapy. Although many clinical studies have shown the effectiveness of hyperthermia for treatment of the head-and-neck (H&N) cancer, the presence of large vessels, tissue transitions and critical tissues in the head and neck poses therapeutic challenges for treatment of advanced tumors in this region. Late side-effects of conventional therapies in treatment of brain tumors in children have been made hyperthermia an attractive method. However, heating tumors in the brain is even more challenging because of its high sensitivity, high thermal conductivity and high perfusion. In this thesis microwave hyperthermia applicators are presented for efficient heating of the H&N and brain tumors. For this purpose, an ultra-wideband antenna has been designed, built and evaluated to act as the radiating element of microwave hyperthermia applicators. The time reversal focusing technique is used to target electromagnetic energy into the tumor. To obtain more accurate treatment planning, the effect of frequency and virtual source positions, in the time-reversal method, are studied for different tumor sizes and tumor positions. The optimal detailed design of the applicator, such as the number of antennas and the antenna positions are also investigated. In the second part of the thesis, the focus is on the applicators for treatment of the brain tumors in children. Helmet applicators are presented and the effect of the number of antennas and the frequency are investigated on the performance of the applicators for heating large and deep-seated brain tumors. Finally, the optimum position of antennas in helmet applicators are found by performing optimization on simplified and realistic models of the child head.
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| 21. |
- Takook, Pegah, 1982, et al.
(författare)
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Performance evaluation of 2 hyperthermia applicators for deep-seated brain tumors
- 2017
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Ingår i: IEEE MTT-S International Microwave Bio Conference (ImBioC), Göteborg, Sweden, May 2017. - 9781538617137
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Konferensbidrag (refereegranskat)abstract
- The performance of two hyperthermia applicatorsin heating deep seated brain tumors is investigated in terms ofhyperthermia quality indicators. The antenna elements in bothapplicators are arranged in a helmet-shape format on a sphericalphantom of head. Self grounded bow-tie antennas immersed inconical water containers, are employed as the antenna elements.The first applicator consists of 26 antenna elements placed on a thin water layer over the phantom. We increased the number of antennas to 58 in the second applicator by employing reduced-sized antenna elements. The computed quality indicators at two tumor locations, deeply seated in the head show that the applicator with 58 antennas presents less absorbed power in healthy tissues at higher frequencies. This decrease is more pronounced for the tumor located in the center of the phantom.
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| 22. |
- Takook, Pegah, 1982, et al.
(författare)
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Performance evaluation of dipole versus modified bow-tie in annular phased array applicators
- 2015
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Ingår i: Progress in Electromagnetics Research Symposium. - 1559-9450 .- 1931-7360. - 9781934142301 ; 2015-January, s. 1909-1912
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Konferensbidrag (refereegranskat)abstract
- Phased arrays are the common type of applicators for deep hyperthermia systems to heat tumors selectively while keeping healthy tissues at normal temperatures. Annular array applicators with dipoles and water bolus have been improved in several studies to deposit energy efficiently in head and neck tumors. In this study we investigate the performance of a modified Bow-Tie antenna versus half-wave dipole as single elements in annular phased array applicators to heat tumors in head and neck region. Hyperthermia quality indicators have been calculated for each case to quantify the quality of treatment outcome in two different tumor positions in a head-and-neck phantom. The obtained results indicates that dipoles are appropriate phased array elements to heat superficial tumors, while modified Bow-Ties are more suitable in heating big deep-seated tumors.
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| 23. |
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| 24. |
- Takook, Pegah, 1982, et al.
(författare)
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Performance Evaluation of Hyperthermia Applicators to Heat Deep-Seated Brain Tumors
- 2018
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Ingår i: IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology. - 2469-7249. ; 2:1, s. 18-24
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Tidskriftsartikel (refereegranskat)abstract
- Addition of hyperthermia to modern cancer therapies is highly effective in improving the treatment outcome of deep-seated head and neck tumors. Brain tumors, on the other hand, are more difficult for heating due to high perfusion and thermal conduction. However, late side effects of conventional therapies in children with brain cancer make it important to combine hyperthermia with these therapies. For this purpose, a hyperthermia applicator capable of efficient heat delivery to large and deep-seated brain tumors is required. In this paper, we evaluate preliminary design of hyperthermia applicators for treatment of deep-seated brain tumors in children. We present three applicators with a different numbers of antennas. The performance of the applicators is compared and evaluated in terms of hyperthermia quality indicators. Although the analysis results in terms of power loss density show that all the applicators are capable of heating sufficiently large deep-seated spherical tumors in our simple head model, more antennas resulted in higher power absorption in the tumors and higher values of tumor coverage.
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| 25. |
- Takook, Pegah, 1982, et al.
(författare)
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Prediction of tumor heatability in microwave hyperthermia applicators
- 2018
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741
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Konferensbidrag (refereegranskat)abstract
- In this paper, the heating efficiency of two hyperthermia applicators has been evaluated for the treatment of tumors in the brain. The effect of a high number of antennas and lower frequencies were investigated by employing one applicator with many antennas and one applicator with antennas operational in a lower frequency range. An investigation method was first used to find out the most difficult and easy places for heating inside the head. Given the applicator, patient model, and tumor position, the method is assessing whether or not the applicators are able to heat the tumor efficiently.
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| 26. |
- Takook, Pegah, 1982
(författare)
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Towards a microwave hyperthermia system for head and neck tumors
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hyperthermia has shown the ability to enhance the performance of radiotherapyand chemotherapy in many clinical trials. The incidence of increased tissue toxicityas a result of high radiotherapy dose, made hyperthermia as a safe methodin combination with radiotherapy to enhance the treatment outcome. Althoughmany clinical studies have shown the effectiveness of hyperthermia for treatmentof head-and-neck (H&N) cancer, presence of large vessels, tissue transitions andcritical tissues in head and neck pose therapeutic challenges for treatment of advancedtumors in this region. Moreover the application of hyperthermia to deepseated tumors in H&N region requires suitable heating equipment which was notavailable until recently.In this thesis, an ultra wideband antenna has been designed, evaluated and builtto act as the radiating element of microwave hyperthermia applicator. The timereversal focusing technique is used to target electromagnetic energy to the tumor.This focusing method is implemented by a 3D finite difference time domain basedcode for tumor models in head and neck.The single antenna element is a modified bow-tie antenna with wideband characteristicover 430-1000 MHz and small size. The antenna size has been reducedconsiderably by immersion in a conical shape water bolus, while maintaining theradiation characteristics in the presence of human phantom. The specific shapeand size of water container, wideband matching network between coaxial portand feeding elements of the bow-tie and addition of low-permittivity dielectricmaterial to the bow-tie radiating arms are the other influential factors on finalperformance of the antenna.The focusing ability of 3D time reversal technique was analyzed using tumormodels in head and neck region of an anthropomorphic phantom. Two hyperthermiaapplicators were designed and used, one for the head and one for the neck.The 3D models of Head&Neck phantom together with phased array applicatorswere modeled in two electromagnetic solvers, CST microwave studio and an inhousedeveloped FDTD-based code.Keywords: microwave hyperthermia, time reversal, wideband antenna, treatmentplanning, head and neck tumors.
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