Research On Microwave Hyperthermia Planning System

There are currently many treatment methods for malignant tumors: including traditional surgical treatment,chemotherapy,radio-physical therapy,and bio-targeted therapy.However,many patients with malignant tumors cannot tolerate traditional surgery.At the same time,some patients with advanced cancer have limited benefit from radiotherapy or chemotherapy,and cannot effectively alleviate the discomfort.Therefore,many local treatment methods are gradually applied to the clinic.Among them,microwave thermotherapy is a promising method?But so far,the microwave thermotherapy is mainly based on the clinical experience of the doctor to design the treatment plan.Its personal subjective factors have a greater impact on the entire treatment process,and even play a decisive role.Then,before the implementation of hyperthermia,the image analysis platform and numerical simulation methods were combined based on computer technology to build a microwave hyperthermia planning system to achieve 3D visualization of the patient's anatomy to assist the doctor to determine the puncture path of the hyperthermia antenna.At the same time,based on the numerical simulation method,the temperature distribution in the hyperthermia area was obtained,and the physician assisted in guiding the type of hyperthermia antenna,hyperthermia power,and treatment time.This articles studies the key technologies for implementing a microwave hyperthermia planning system.The main research contents are as follows:(1)Due to the respiratory movement of the lungs,it is very difficult to accurately predict and control necrosis zone.Therefore,the influence of the changes of the physical parameters of the respiratory process on the microwave ablation zone is studied.Firstly,based on the 4D-CT which was used to describe the respiratory process of the lungs.According to the theory of porous media,the change of the effective thermal conductivity of the lung tissue is obtained.The changes of relative permittivity,conductivity and density changes during the breathing process are also considered.At the same time,a pulmonary heat transfer model of microwave thermotherapy was established.(2)In order to study the therapeutic effect of microwave thermotherapy in different types of tumors,single-slot coaxial microwave antennas were studied in brain white matter tumors,brain gray matter tumors,breast fat tumors,breast gland tumors,kidney tumors,lung tumors(inflated and In the uninflated state),liver tumors and sarcomas,including SAR values,temperature distribution,and morphological features of the ablation.At the same time,a variety of types of interventional thermotherapy antenna models are also established.A large number of simulation results provide a basis for building a treatment parameter search database in the planning system.(3)Design and implementation of microwave hyperthermia planning system.According to the functional requirements of the system,the planning system is composed of three modules.These modules are the image analysis module,the temperature distribution prediction module of the thermotherapy area,and the treatment parameter output module.It can be unifiedly called on the main interface to realize the corresponding functions,complete the planning of the probe puncture path and the prediction of the optimal treatment parameters.The image analysis module is based on the extension of the 3DSlicer function module to achieve rapid and automated segmentation and three-dimensional reconstruction structural tissues.On this basis,the physician plans the path of the ablation needle to ensure that key locations such as bones and large blood vessels are avoided.In the microwave hyperthermia planning system,the temperature field prediction module of the treatment area is a part that plays a key role,and achieve visualization of hyperthermia injury area.The treatment parameter automatic output module is based on the "search" matching algorithm.The principle is to quickly search the database for the best matching conformal hyperthermia results according to the ideal treatment requirements put forward by the physician.It then automatically outputs the treatment parameters in the reverse direction to assist the doctor.Finally,the accuracy of the treatment effect predicted by the microwave hyperthermia planning system and the accuracy of the output treatment parameters were verified.The results show that the prediction of the long-axis and short-axis parameters of the thermal ablation area is basically consistent with the results of in vitro experiments,The average error of output treatment power and treatment time is less than 6W and 0.5min,respectively.The system can provide auxiliary guidance for the formulation of a microwave hyperthermia surgical plan.