In this work we have measured the dose distribution and the percent depth dose of 20 MeV electron beam using the X-OMAT films in order to verify the effects of transverse magnetic field on high energy elecrtron beam in a phantom. The result shows about 30% increase of the percent depth dose at 4.5 cm depth under the transverse magnetic field of 1.5 Tesla at 7.5 cm depth. We have verified that these were in an agreement with other theoretical results.
Magnetic Fields*

Electromagnetic Fields ; Magnetic Fields ; Microwaves ; adverse effects ; Television

BACKGROUND: So many electronic devices have been introduced in the operating room. However, little was known about the hazards of electromagnetic fields (EMF) to the human body. We have studied about how much the anesthesiologists are exposed to EMF. METHODS: In 19 operating rooms of our hospital, the intensity of magnetic fields was measured by an ELF (Extremely low frequency) field strength measurement system. The distances were 30 cm, 50 cm and the anesthesiologist's proximity to the monitoring devices. RESULTS: The average strength of 19 operating rooms were 2.22 +/- 1.13 mG at 30 cm from the monitors, 1.29 +/- 0.84 mG at 50 cm and 1.00 +/- 0.78 mG at the anesthesiologist's stand. CONCLUSIONS: We found that in some of our operating rooms the exposure to EMF was measured above Sweden's TCO limit which has been accepted as the EMF radiation rule for computer monitors. Although the hazards of EMF have not been definitely confirmed yet, the effort not to be exposed to EMF should be considered by anesthesiologists.
Electromagnetic Fields* ; Human Body ; Magnetic Fields ; Magnets* ; Operating Rooms*

The purpose of this study was to evaluate the effects of magnetic field on cellular activity of MC3T3-El cells. The celular activity was monitored by alkaline phosphatase and DNA synthetic activity in control, static magnetic field and pulsed electromagnetic field groups. A static magnetic field was applied to the cell by placing one, two, three, four, and five samarium-cobalt magnets above and below each cell plate for 24hours per day. A pulsed electromagnetic field with a frequency of 100 herz was applied for 10 hours per day. After 10 days of magnetic field exposure, there were increase of alkaline phosphatase activity in static magnetic field groups consisted of one, two and three magnetic groups, Alkaline phosphatase activities were not significantly increased in four and five magnetic groups, Application of pulsed electromagnetic field did not result in significant increase in alkaline phosphatase activity compared to control. DNA synthetic activity in both static and pulsed electromagnetic field group were not significantly different from that in control group, The result of this study suggest that magnetic field could have effect on the metabolism of bone cells related to the cellular metabolic process,
Alkaline Phosphatase* ; DNA* ; Electromagnetic Fields* ; Magnetic Fields* ; Magnets* ; Metabolism

This paper mainly studies the driving system of centrifugal blood pump for extracorporeal circulation, with the core being disc magnetic coupling. Structure parameters of disc magnetic coupling are related to the ability of transferring magnetic torque. Therefore, it is necessary to carry out disc magnetic coupling permanent magnet pole number (n), air gap length (L(g)), permanent magnet thickness (L(m)), permanent magnet body inside diameter (R(i)) and outside diameter (R(o)), etc. thoroughly. This paper adopts the three-dimensional static magnetic field edge element method of Ansys for numerical calculation, and analyses the relations of magnetic coupling each parameter to transmission magnetic torque. It provides a good theory basis and calculation method for further optimization of the disc magnetic coupling.
Extracorporeal Circulation ; Magnetic Fields ; Magnetics ; Torque

To evaluate the effect of a static magnetic field on the bone producing potential of MC3T3 El cells, the alkaline phosphatase activity was measured after the cells having been cultured under 76.4mT static magnetic field using a SmCos magnets for 5days, 7days, lldays, 15days and 2ldays for each cell culture group. Also, the amount of bone nodule stained with Alizarin red S was observed. The results were as follows. · The alkaline phosphatase activity of the 7, 11, and 15 days group among the experimental groups was decreased as compared with the control groups, and the decrease of alkaline phosphatase activity in the 11 days group was the most evident among them. · Any stained bone nodules of both groups had not been observed until the 11th day. The stained bone nodules in the control groups were found on the 15th day, but not in the experimental groups. The stained bone nodules were observed in both groups on the 21st day, but the control groups have more bone nodules than the experimental groups.
Alkaline Phosphatase ; Cell Culture Techniques ; Magnetic Fields*

This paper realized an electromagnetic tracking system based on electrically-controlled rotating magnetic field. A tracking system using the digital signal processor (DSP) as the control processing device was developed, including a controllable constant current source module, a magnetic field source module, a three-axis magnetic sensor and ADC interface circuit. The experimental results verified that each time the system could be stable positioning, average error of position was 0.282 cm, the average error of orientation was 0.696o, the positioning time was 1.572 s. Through calibration and further improvement of the hardware circuit, the performance of the system is expected to further improve.
Calibration ; Electromagnetic Phenomena ; Equipment Design ; Magnetic Fields

PURPOSE: A pulsed arterial spin labeling (PASL) signal usually depends on several parameters. The objective of this study was to determine the optimal parameters using simulation for perfusion signals of PASL magnetic resonance imaging (MRI). MATERIALS AND METHODS: Perfusion signals, DeltaM/M(0b), derived from the Bloch equation were evaluated in regard to the four most important parameters in PASL MRI: the tissue-to-blood coefficient (lambda), the longitudinal relaxation time of blood (T(1b)), the arterial transit delay from the application of tag (deltat), and the magnetic field strength (B0). The simulation was conducted with Mathematica software. RESULTS: First, perfusion signals differed depending on the value of lambda in brain tissue. The maximum signal, DeltaM/M(0b) = 0.390, was obtained at an inversion time (TI) = 1.53 sec for gray matter on 3T MRI. Second, perfusion signals were reduced with increasing deltat. The maximum signal, DeltaM/M0b = 0.526, was obtained at TI = 2.1 sec for deltat = 0.5 sec. Finally, perfusion signals increased with increasing B0. The maximum signal, DeltaM = 1.15, was obtained at TI = 1.52 sec for 3T MRI. CONCLUSION: We reported that the optimized TI values were obtained to provide the highest PASL signals. It is very important that optimized TI values be used to obtain high-quality perfusion signals using PASL MRI.
Brain ; Magnetic Fields ; Magnetic Resonance Imaging ; Perfusion ; Relaxation

Magnetic susceptibility is an intrinsic physical quantity which describes the relationship between material magnetization and applied external magnetic field. Quantitative susceptibility mapping (QSM) is an MRI technology which can quantify the buck magnetic susceptibility of tissue in vivo. It is particularly effective at elucidating anatomy with paramagnetic or diamagnetic components. QSM technology is a method for solving the ill-pose problem of unconventional de-convolution of the measured tissue magnetic field with the unit magnetic dipole field to obtain the susceptibility source map. Many multi orientation scan based QSM and clinically acceptable single orientation QSM methods have been proposed to solve this ill-posed problem. In this paper, the QSM concept is introduced and the various QSM methods are systematically categorized and discussed. The aim of this paper is to summarize the current research progress of QSM, popularize the knowledge of QSM and promote the improvements and the rational application of QSM in clinical field.
Humans ; Magnetic Fields ; Magnetic Resonance Imaging ; trends ; Magnetics

According to the features of the open permanent MRI system, this paper designs the gradient magnetic field, in which the designed parameters are optimized. The simulation experiments demonstrate the effectiveness of the algorithm.
Algorithms ; Equipment Design ; Magnetic Fields ; Magnetic Resonance Imaging ; instrumentation