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

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

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

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

Development of an ultrasonic hyperthermia instrument's software based on ARM32 microprocessor is here introduced. The system integrates the embedded SOC system, memory system, PWM system, A/D system, JTAG debug system, UART communication system, I/O system and GUI system (include LCD, keyboard) in one PCB board. It effectively completes the control and constance of temperature through the improved PID algorithm, and the instrument miniaturization. Experiments have proved that the system accords with the design requirements.
Algorithms ; Humans ; Hyperthermia, Induced ; instrumentation ; Signal Processing, Computer-Assisted ; instrumentation ; Software Design ; Temperature ; Ultrasonics

Small-scale intellectualized medical instrument has attracted great attention in the field of biomedical engineering, and LabVIEW (Laboratory Virtual Instrument Engineering Workbench) provides a convenient environment for this application due to its inherent advantages. The principle and system structure of the hyperthermia instrument are presented. Type T thermocouples are employed as thermotransducers, whose amplifier consists of two stages, providing built-in ice point compensation and thus improving work stability over temperature. Control signals produced by specially designed circuit drive the programmable counter/timer 8254 chip to generate PWM (Pulse width modulation) wave, which is used as ultrasound radiation energy control signal. Subroutine design topics such as inner-tissue real time feedback temperature control algorithm, water temperature control in the ultrasound applicator are also described. In the cancer tissue temperature control subroutine, the authors exert new improvments to PID (Proportional Integral Differential) algorithm according to the specific demands of the system and achieve strict temperature control to the target tissue region. The system design and PID algorithm improvement have experimentally proved to be reliable and excellent, meeting the requirements of the hyperthermia system.
Algorithms ; Computer Simulation ; Hyperthermia, Induced ; instrumentation ; Neoplasms ; therapy ; Software Design ; Ultrasonic Therapy ; instrumentation ; methods

This paper introduces double ultrasound pulse transmitting and receiving circuits used in ultrasound thermometry. Using the circuits, double ultrasound pulses could be made synchronously to satisfy the requirements of ultrasound thermometry, and the weak ultrasound echo signals are received successfully. The crux experiment waveform offered shows that the circuits have high reliability.
Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; Neoplasms ; therapy ; Pulse ; Temperature ; Transducers ; Ultrasonography ; instrumentation ; methods

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.

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

The basic objective of microwave hyperthermia is to raise the temperature in the tumor tissue without overheating point for a long time. It's difficult to achieve uniform temperature distribution using the continuous heating without changing the antenna shape and inserting position. In this paper, the interstitial antenna worked in the frequency of 2450 MHz inserted into an infinite muscle model is studied. The Finite Difference Time Domoin (FDTD) method was used to calculate the electromagnetic field, while the finite difference method (FDM) was used to analyze the temperature distribution in tumor tissue. The simulation results show that the long-time evenly heating can be achieved by using the alternately heating process and the treatment area can be changed by adjusting input power.
Electromagnetic Phenomena ; Humans ; Hyperthermia, Induced ; instrumentation ; Microwaves ; therapeutic use ; Neoplasms ; therapy ; Temperature