In order to support study of new radiofrequency ablation treatments and finally realize of precise conformal ablation of targeted tissue, this paper proposed a system which is able to generate radio frequency currents at different frequencies. The designed system bases on the basic principle of Class E power amplifier and uses MSP430 microcontroller as a controller and uses a touch screen as human-machine interface to design a frequency-selectable radiofrequency ablation treatment system,. The RF signals at frequencies of 230 kHz, 460 kHz, 920 kHz, and 2 000 kHz were tested to verify the feasibility of the system, and by using a tissue phantom, tested the heating ability of the RF signals at frequencies of 460 kHz, 920 kHz, and 2 000 kHz. The results show the device could well heat the tissue at the three frequencies. The study has also found that both the highest temperature and the ablation area decreases with RF frequency, when using the constant power control mode.
Catheter Ablation ; instrumentation ; Hot Temperature ; Humans ; Hyperthermia, Induced ; Phantoms, Imaging ; Radio Waves

We developed an ultrasound tumor hyperthermia instrument by optimizing the embedded platform and system units construction to realize miniaturization and portability. The instrument can accurately and safely control the target temperature by using PID feedback algorithm.
Algorithms ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; Neoplasms ; therapy ; Ultrasonic Therapy ; instrumentation ; methods

A safety protection method which can be used on perfusion hyperthermia Instrument. The method is based on temperature sensor, weighing sensor, and programming and featured with safe and simple, easy to achieve, fault detection, quick response.
Equipment Design ; Equipment Safety ; Hyperthermia, Induced ; adverse effects ; instrumentation

In clinical application of microwave hyperthermia, multi-applicators are often simultaneously required to irradiate the tumor because of its large volume or its deep location. Power divider separates the input microwave energy into equal, or unequal, energy to each applicator. In this paper, the design procedure for the three-section transmission-line transformer based one-to-two equal-split Wilkinson power divider is introduced. By impedance analysis on equivalent scheme, the design parameter of power divider is provided, and by simulation and optimization on Ansoft HFSS, a microstrip structure Wilkinson power divider operating frequency 2. 45 GHz is given. Measurement test results from network analyzer show that it has 25% bandwidth and good isolation in output with this structure. Besides, it is characterized by small size and easy processing. This power divider suits microwave hyperthermia.
Electric Impedance ; Electromagnetic Phenomena ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; Microwaves ; Neoplasms ; therapy

OBJECTIVEA 2.45 GHz microstrip applicator using single rectangle sheet structure is presented.

METHODSBased on the radiant principle of microstrip antenna, the applicator's parameter is designed and the simulating model is set and optimized in HFSS.

RESULTSMeasured by network analyzer, the technical target of this applicator is complied with design demand. During irradiation experiment, based on 30 W power, 30 mm radiation distance and 15 min duration experiment condition, the thermal field distribution map of phantom is obtained from the far-infrared image instrument. The 3D map shows that the region of thermal field centre has small radius and deep heat penetration.

CONCLUSIONThe microwave energy from this applicator can reach the tumor in superficial layer without heat injuring normal tissue around it.

A new 2450MHz invasive antenna for microwave hyperthermia is designed in this paper. The finite element method is employed to simulate the choke antenna and improved choke antenna, i.e., choke-umbrella antenna. The specific absorption rates (SAR) in tumors are calculated with the two kinds of antennas. S11 of choke-umbrella antenna is also compared with that of choke antenna. Multi-layered block of tissue-equivalent phantom is heated with the fabricated invasive antenna. The distribution of the temperature field in the invasive layer as well as the three-dimensional distribution of the temperature field in phantom is obtained with an infrared thermo graphic technique. Research results show that the improved choke-umbrella antenna can generate more uniform temperature distribution and meets the requirements of the actual clinical microwave hyperthermia better.
Equipment Design ; Hyperthermia, Induced ; instrumentation ; Microwaves

The combination of the cryosurgery using LN2 and intelligent RF ablation therapeutic instrument based on the theory of local destruction is introduced in this paper, and this alternating therapy is believed to have a better controlling effect on tumor ablation. In heating period, a fuzzy algorithm is used to control the RF power to realize a more smoothly heating process to the target area.
Catheter Ablation ; instrumentation ; methods ; Cryosurgery ; instrumentation ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; methods ; Neoplasms ; surgery

Blood temperature-varying has been widely applied in clinical practice such as extracorporeal circulation for whole-body perfusion hyperthermia (WBPH), body rewarming and blood temperature-varying in organ transplantation. This paper reports a novel DCS (Computer distributed control)-based blood temperature-varying system which includes therapy management function and whose hardware and software can be extended easily. Simulation results illustrate that this system provides precise temperature control with good performance in various operation conditions.
Body Temperature ; Computing Methodologies ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; methods ; Software

High-intensity focused ultrasound (HIFU) thermotherapy is a promising technique for local tumor destruction of solid organs. Temperature is the important parameter which impacts the curative effects of thermotherapy. For safety and efficiency reasons, it is necessary to monitor the temperature changes inside body in real-time, non-invasively and precisely. Recently MRI methods employed for temperature monitoring during HIFU therapy have been paid more and more attentions to. This paper introduces the general principles of non-invasive temperature monitoring using MRI. The authors also review the development of this technique and point out some problems that need to be solved.
Animals ; Body Temperature ; physiology ; Humans ; Hyperthermia, Induced ; instrumentation ; Magnetic Resonance Imaging ; methods ; Monitoring, Physiologic ; methods ; Neoplasms ; therapy

Mn0.5Zn0.5Fe2O4 nano-particles were prepared by the chemical co-precipitation, their characteristics were observed with transmission electron microscope (TEM), X-ray diffractometer (XRD) and thermal analysis system, and etc. The temperature changes of the nano-particles of Mn0.5Zn0.5Fe2O4 and its magnetic fluid explored in radiofrequency(RF,200 KHz, 4 KW) were measured. The proliferation ratio of L929 cells cultured in soak of Mn0.5Zn0.5Fe2O4 nano-particles were observed. The experiment indicates that the magnetic particles were about 40 nm diameter in average, round, had strong magnetism, and were proved to be consistent with the standard data of chart of XRD. Its magnetic fluid exposed to RF could be heated up to temperature range from 40 degrees C to 51 degrees C due to the amount of the magnetic nano-particles and intensity of the alternating magnetic field. Magnetic nano-particles were found to have no obvious cytotoxicity to L929 cells.
Animals ; Cell Line ; Ferrous Compounds ; Hyperthermia, Induced ; Magnetics ; instrumentation ; therapeutic use ; Manganese ; Materials Testing ; Mice ; Nanostructures ; Zinc