Coil design and simulation analysis of magnetic induction hyperthermia in rats / 中国医学物理学杂志

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.

Research progress in medical imaging methods based on magnetoacoustic effect / 国际生物医学工程杂志

Electrical property imaging based on the magnetoacoustic effect has the advantages of non-invasiveness, high contrast, and high spatial resolution, making it a promising technique for early disease diagnosis. In this paper, the representative research progress of three magnetoacoustic multi-physical field coupled methods are reviewed, including magnetoacoustic tomography combined with magnetic induction (MAT-MI), magnetoacoustic tomography combined with current injection (MAT-CI), and magneto-acousto-electrical tomography (MAET). Additionally, the future development of these techniques is also discussed.

Design and Analysis of a New Cerebrospinal Fluid Drainage Separation Device / 医用生物力学

Objective Based on the existing clinical drainage device, two novel mechanisms were designed for the connection between the drainage tube of the patient and the drainage tube of the drainage bag, so as to compare such two mechanisms and validate whether the mechanisms can meet the design requirements for clinical use. Methods Mechanism 1 used the method of electromagnetic drive to pull in and Mechanism 2 used the magnetization method of permanent magnet to pull in. The finite element model of static electromagnetic field was established. The force of the two mechanisms under different currents was compared, and the distribution of magnetic field lines and magnetic induction intensity was analyzed. Simulation experiments were designed for preliminary experimental research. Results Under the pull-in state, the maximum magnetic induction of Mechanism 1 and Mechanism 2 at the closed end surface was found in contact area of the two iron cores. The suction force of Mechanism 1 could be adjusted by the current. When the current was 1 A, the maximum magnetic induction intensity at the closed end was 0.76 T, the electromagnetic force measured by the experiment was 6.08 N, the magnetic force of Mechanism 2 was 6.68 N, which was smaller than the 8 N suture tension. Mechanism 2 was separated by supplying the driving coil with a reverse magnetic field. Conclusions When the current was 1 A, Mechanism 1 could meet the magnetic attraction requirements, and Mechanism 2 could be separated when the current reached 1.8 A. Both mechanisms met the requirements of clinical design, but Mechanism 2 was more secure in the process of application. The feasibility of the mechanism structure was verified by finite element analysis and experimental test.

Assessment of scoliosis in adolescence and adults by 3-D ultrasound imaging:a pilot study / 中华超声影像学杂志

Objective To assess scoliosis in adolescence and adults by three-dimensional ( 3-D ) ultrasound imaging . Methods A commercial available ultrasound instrument with a magnetic sensor system was used for long distance 3-D ultrasound imaging .Specific phantoms were imaged to evaluate the precision of this imaging system . Twenty healthy adults and 20 patients with scoliosis were imaged by 3-D ultrasonography and radiography . The deformity angle of the patients with scoliosis was measured on the reconstructed coronal plane ( C plane) of 3-D ultrasound imaging . The relevance between the curvature measured by ultrasound and the Cobb angles originated by radiography were evaluated . Results There was no significant difference between the angles of the phantom measured by the 3-D ultrasound imaging system and that measured by an angle gauge ( P = 0 .479) . The transverse process ,vertebral arch and acoustic shadow of the central spinous process of spines in healthy adults can be displayed on the reconstructed C plane by 3-D ultrasound imaging . The morphology of scoliosis in all the twenty patients can be observed on the reconstructed C planes ( multi-layers) by 3-D ultrasound imaging ,which accorded well with that observed on radiograph . In 9 patients ,part of the spinal segment could not be totally displayed on one single coronal plane and no additional measurement was carried out . In 11 patients ,all the segments of the spine could be clearly displayed on a single coronal plane and the curvature of scoliosis was then measured . There were no significant differences between the angle measured on 3-D ultrasound imaging and the Cobb angle measured on radiograph( P =0 .974) and the two measurement methods have high correlation( r =0 .991 , P <0 .0001) . Conclusions The commercial available 3-D ultrasound imaging system applied in this study offers a viable method to assess scoliosis in adolescence and adults in a reliable and radiation-free manner .

The biological effects of magnetic fields on microvascular endothelial cells in the human brain / 中华物理医学与康复杂志

Objective To observe the biological effects of magnetic fields of different intensities on microvascular endothelial cells in the human brain (HBMECs).Methods HBMECs were cultured in vitro under normal conditions and randomly divided into a control group and several magnetic induction groups——26 mT,62.5 mT,110.7 mT and 215.6 mT at the center pole.Any changes to the cytomembranes were observed 72 h after planking using the lactate dehydrogenase (LDH) method.Superoxide dismutase and malondialdehyde methods were used to detect cellular oxidation due to the magnetic field.An inverted microscope was used to observe any changes in cell morphology,and flow cytometry was employed to detect cell apoptosis.Results Compared with the control group,the LDH value of the 215.6 mT group was significantly higher,but there were no significant differences in oxidative damage,apoptosis or morphology observed.Moreover,there were no significant differences between the controls and the 26 mT,62.5 mT and 110.7 mT groups in any of the above measurements.Conclusion Magnetic fields of different intensity have different biological effects on HBMECs.A 215.6 mT magnetic field influences their cell membranes but causes no oxidative damage,cell apoptosis or morphological changes.These observations and the mechanism need further exploration.

Application of pancreaticogastrostomy and pancreaticojejunostomy in central pancreatectomy / 第二军医大学学报

Objective To assess the effects of applying pancreaticogastrostomy and pancreaticojejunostomy in central pancreatectomy on postoperative outcome and short-term complications. Methods The clinical data of 25 patients who received central pancreatectomy from May 2013 to May 2015 were retrospectively analyzed. The reconstruction methods were pancreaticogastrostomy or pancreaticojejunostomy, and the pancreatic duct were anastomosed with stomach or intestinal mucosa lips openings by magnetic induction line suture. Then the postoperative pancreatic fistula and hospital stay were compared between the two groups. Results The baseline data of two groups were comparable, and there were no significant differences in postoperative pancreatic fistula rates or hospital stay between the two groups. The 25 patients did not have anastomotic bleeding. Two cases with proximal pancreatic stump fistula were observed and were cured by adequate drainage, octreotide acetate injection, parenteral nutrition and so on. Conclusion Central pancreatectomy can better maintain the pancreas function. pancreaticogastrostomy and pancreaticojejunostomy are both safe.

Detection of acute cerebral hemorrhage in rabbits by magnetic induction

Acute cerebral hemorrhage (ACH) is an important clinical problem that is often monitored and studied with expensive devices such as computed tomography, magnetic resonance imaging, and positron emission tomography. These devices are not readily available in economically underdeveloped regions of the world, emergency departments, and emergency zones. We have developed a less expensive tool for non-contact monitoring of ACH. The system measures the magnetic induction phase shift (MIPS) between the electromagnetic signals on two coils. ACH was induced in 6 experimental rabbits and edema was induced in 4 control rabbits by stereotactic methods, and their intracranial pressure and heart rate were monitored for 1 h. Signals were continuously monitored for up to 1 h at an exciting frequency of 10.7 MHz. Autologous blood was administered to the experimental group, and saline to the control group (1 to 3 mL) by injection of 1-mL every 5 min. The results showed a significant increase in MIPS as a function of the injection volume, but the heart rate was stable. In the experimental (ACH) group, there was a statistically significant positive correlation of the intracranial pressure and MIPS. The change of MIPS was greater in the ACH group than in the control group. This high-sensitivity system could detect a 1-mL change in blood volume. The MIPS was significantly related to the intracranial pressure. This observation suggests that the method could be valuable for detecting early warning signs in emergency medicine and critical care units.

A Review of Assistive Listening Device and Digital Wireless Technology for Hearing Instruments

Assistive listening devices (ALDs) refer to various types of amplification equipment designed to improve the communication of individuals with hard of hearing to enhance the accessibility to speech signal when individual hearing instruments are not sufficient. There are many types of ALDs to overcome a triangle of speech to noise ratio (SNR) problems, noise, distance, and reverberation. ALDs vary in their internal electronic mechanisms ranging from simple hard-wire microphone-amplifier units to more sophisticated broadcasting systems. They usually use microphones to capture an audio source and broadcast it wirelessly over a frequency modulation (FM), infra-red, induction loop, or other transmission techniques. The seven types of ALDs are introduced including hardwire devices, FM sound system, infra-red sound system, induction loop system, telephone listening devices, television, and alert/alarm system. Further development of digital wireless technology in hearing instruments will make possible direct communication with ALDs without any accessories in the near future. There are two technology solutions for digital wireless hearing instruments improving SNR and convenience. One is near-field magnetic induction combined with Bluetooth radio frequency (RF) transmission or proprietary RF transmission and the other is proprietary RF transmission alone. Recently launched digital wireless hearing aid applying this new technology can communicate from the hearing instrument to personal computer, phones, Wi-Fi, alert systems, and ALDs via iPhone, iPad, and iPod. However, it comes with its own iOS application offering a range of features but there is no option for Android users as of this moment.

A review of transcranial magnetic stimulation.

Transcranial magnetic induction is a promising and powerful tool in the field of neuropsychiatry and has widespread application in basic neurophysiological & neuropsychiatric research, treatment of depression and other psychiatric disorders. Since it is a relatively new technique approved by the FDA, more prospective studies and clinical trials are needed to provide more accurate data and help optimize the treatment.

The clinical application of magnetic induction hyperthermia and analysis of thermal field / 中华放射肿瘤学杂志

Objective To study the laws of heating and thermal field of heating seed arrays in different magnetic field intensity during the magnetic induction hyperthermia.Methods 3.0 cm×3.0 cm ×2.6 cm and 5.0 cm ×5.0 cm×2.6 cm of magnetic heating seed was implanted respectively in 10.0 cm×10.0 cm ×10.0 cm pure agar phantom.The regions was divided into one file per 5 Gs in the range of 60-120 Gs magnetic induction.The temperature measurement experiments were implemented in each sub-file.Muscle-agar mixture model was used in the magnetic induction 60 Gs and 90 Gs to implement GTV-heating simulation experiments and thermal field analysis.Results The pure agar phantom heating experiments show that the heating is of basically the same rule when seeds with various diameters were implanted in the magnetic thermal array.Along with the increase of magnetic induction,the final temperature of the focal point heated for 40 min increased accordingly.and time required for heating to 50℃ was shortened correspondingly.The thermal field analysis of muscle-a mixture agar mixture model showed that the implantation density of magnetic heating seed is closely associated with the temperature of the target area and thermal field in difierent magnetic field intcnsity.Conclusions The magnetic induction has a significant impact on heating of the seeds,as the magnetic modium,and this impact is trending downwards when the magnetic field reaches a certain intensity.Within a certain size,adequate magnetic heating seed density is necessary to achieve the desired temperature required for the temperature value.The heating seeds should be put in a certain order to heat the venue evenly,not in a simply order,but in line with the principle of outer dense and inner sparse.

Impact of metal thermoseeds on radiation dose distribution / 中华放射肿瘤学杂志

Objective To study the impact of implanted thermoseeds of magnetic induction hyperthermia on radiation dose distribution. Methods To simulate irradiation, an anthropomorphic phantom and three-dimensional treatment planning system were used. The impact of thermoseeds on radiation dose distribution was evaluated. Results The change of absorbed dose caused by the implantated thermoseeds was less than 1.5%. Conclusions The impact of implanted thermoseeds on radiation dose distribution is small and comes up to the requirements that the total target dose uncertainty must be less than 5%. Therefore, the impact of thermoseeds on the absorbed dose in tissue can be ignored in clinical practice.

Some Kinds of Developing Techniques and Systems of Electrical Impedance Tomography / 医疗卫生装备

The development of EIT is summarized based on the concept and advantages of the Electrical impedance tomography (EIT) from the following three aspects: multi-frequency electrical impedance tomography (MEEIT), induced current electrical impedance tomography (ICEIT)and magnetic induction tomography (MIT). The advantages of the developing methods are expatiated and compared with the traditional EIT . The future application trend of them is pointed out. EIT is one of the key projects of biomedical engineering today. It is an ideal medical imaging technology with enticing prospect.

The calculating method of space magnetic induction of circular permanent magnet in the field of magnetic biologY efiect． / 中国医学物理学杂志

Formulas, which are applied to the space magnetic induction of circular permanent magnet, are deduced from BiotSavart-Laplaces law in electromagnetics. The calculating methods of the formulas are set up with numerical integral and computer program. The space quantity distribution of magnetic induction of a circular permanent magnet is obtained through an objective example. These provide theory basis for the magnet application in the field of magnetic biology effect.

Study on technique of phase detection in magnetic induction tomography / 医疗卫生装备

In the magnetic induction tomography(MIT) system,the electrical conductivity of biological tissue is direct proportion to the phase difference between the excitation signal and the detection signal.To obtain the image of the contribution of tissue's electrical conductivity,the system must have the function of phase detection with high accuracy.The paper focuses on the means of digital phase detection,including FFT method,the correlation method and the classic method,which are ultimately compared with analogue phase detection method.The experimental results show that FFT method and the correlation method,with low error level and high linearity,can better detect the phase difference with the level of 0.1?.The digital phase difference detection provides a kind of effective method for MIT system.

Development of Measuring Apparatus for Magnetic Induction / 医疗卫生装备

Objective To develop an apparatus to measure pulse magnetic field. Methods Single chip computer and Hall-effect integrated circuit was utilized to measure the magnetic induction. The correlative hardware and software flow were given. The measuring range of apparatus was 0-50mT. Results The circuit was simple and the performance was safe and credible. The measuring precision was high. Conclusion It can be used for some kinds of magnetic induction measurement.