ABSTRACT
A Helmholtz coil is selected to generate the alternating magnetic field,and the relevant model is established with a rat brain tumor as the research object.Based on the Pennes bioheat transfer equation,the electromagnetic field distribution and temperature field distribution are calculated in COMSOL simulation software,and the factors affecting the outcome of magnetic induction hyperthermia are analyzed.The results show that both magnetic field distribution and temperature field distribution meet the requirements for magnetic induction hyperthermia.The magnetic field distribution in the tumor treatment area is uniform,and the central magnetic induction strength is 12.847 mT.The temperature rise in the tumor area is significant,and the temperature at the tumor center is 46℃or above,basically reaching the treatment temperature.The therapeutic efficacy of magnetic induction hyperthermia is affected by the number of turns,current,radius and spacing,magnetic field frequency and other parameters.The study provides reference for the clinical application of magnetic induction hyperthermia and the coil design.
ABSTRACT
Objective To propose two different types of information encoding methods for the information encoding mode of neuronal networks based on Hodgkin-Huxley(HH)model.Methods The biological neuronal networks with different topologies were built with numerical simulations using HH model and chemical synapses.The specificities of two information encoding methods,namely average frequency encoding and interspike interval encoding,under the stimulus of sinusoidal signals and random audio signals were investigated,and the information encoding mode of neuronal networks stimulated by different signals was also analyzed.Results The information encoding mode of the neuronal networks was correlated with the stimulus signal type.When being stimulated by a continuous periodic signal,the neuronal network would generate a discharge sequence with periodicity corresponding to the stimulus signal.When the stimulus signal was a random signal,the discharge rate of the neuronal network would change with the stimulus signal intensity,and the higher the stimulus signal intensity was,the higher the action potential discharge rate was.Under the same stimulus signal,the temporal structure of the neuronal network discharge sequence was affected by the topology of the neuronal network.Conclusion The information encoding mode of neuronal networks is correlated with the stimulus signal,and the temporal structure of the discharge sequence of neuronal networks with different topologies is different.Interspike interval encoding has higher accuracy and contains more information,and the combination with the average frequency encoding can effectively express the dynamic change of the information encoding mode of neuronal networks under the stimulus.
ABSTRACT
Cholangiocarcinoma is a highly malignant tumor. It is not sensitive to radiotherapy and chemotherapy and has a poor prognosis. At present, there is no effective treatment. As a new method for treating cancer, magnetic fluid hyperthermia has been clinically applied to a variety of cancers in recent years. This article introduces it to the cholangiocarcinoma model and systematically studies the effect of magnetic fluid hyperthermia on cholangiocarcinoma. Starting from the theory of magnetic fluid heating, the electromagnetic and heat transfer models were constructed in the finite element simulation software COMSOL using the Pennes biological heat transfer equation. The Helmholtz coil was used as an alternating magnetic field generating device. The relationship between the magnetic fluid-related properties and the heating power was analyzed according to Rosensweig's theory. After the multiphysics coupling simulation was performed, the electromagnetic field and thermal field distribution in the hyperthermia region were obtained. The results showed that the magnetic field distribution in the treatment area was uniform, and the thermal field distribution met the requirements of hyperthermia. After the magnetic fluid injection, the cholangiocarcinoma tissue warmed up rapidly, and the temperature of tumor tissues could reach above 42 °C, but the surrounding healthy tissues did not heat up significantly. At the same time, it was verified that the large blood vessels around the bile duct, the overflow of the magnetic fluid, and the eddy current heat had little effect on thermotherapy. The results of this article can provide a reference for the clinical application of magnetic fluid hyperthermia for cholangiocarcinoma.
Subject(s)
Humans , Cholangiocarcinoma , Hyperthermia , Hyperthermia, Induced , Magnetic Fields , MagneticsABSTRACT
In this paper, we established magnetic fluid hyperthermia (MFH) model for rat tumor using the finite element software COMSOL based on the linear response theory. By analyzing four kinds of magnetic medium within relaxation mechanism, such as Fe O 、FeCo、fccFePt and L1 FePt, we studied the influence of the change of magnetic medium radius on dissipation power and temperature field, respectively. At the same time, the optimization method for the parameters of several magnetic medium is proposed, and the applications of four kinds of magnetic medium are given as well. By increasing the dissipation power of the magnetic medium as much as possible, the dose of magnetic medium used in the treatment can be reduced, meanwhile, the adverse effects on health tissue surrounding the tumor will be minimized. The conclusions of this paper can provide reference for magnetic medium preparation applied to MFH.
Subject(s)
Animals , Rats , Hot Temperature , Hyperthermia, Induced , Magnetics , Neoplasms , TherapeuticsABSTRACT
Neuron is the basic unit of the biological neural system. The Hodgkin-Huxley (HH) model is one of the most realistic neuron models on the electrophysiological characteristic description of neuron. Hardware implementation of neuron could provide new research ideas to clinical treatment of spinal cord injury, bionics and artificial intelligence. Based on the HH model neuron and the DSP Builder technology, in the present study, a single HH model neuron hardware implementation was completed in Field Programmable Gate Array (FPGA). The neuron implemented in FPGA was stimulated by different types of current, the action potential response characteristics were analyzed, and the correlation coefficient between numerical simulation result and hardware implementation result were calculated. The results showed that neuronal action potential response of FPGA was highly consistent with numerical simulation result. This work lays the foundation for hardware implementation of neural network.