ABSTRACT
Objective To explore the magnetic properties of permanent magnet wafers commonly used in magnetotherapy to provide a basis for the scientific and rational use of sources of magnetism.Methods A magnetometer was used to measure the magnetic induction intensities of the N and S polar centers of eight groups of magnet wafers (axial magnetization) with nominal magnetic induction intensities of 6 mT, 10 mT, 20 mT, 30 mT, 60 mT,100 mT, 200 mT and 350 mT.Results There were some differences between the nominal values and the measured mean magnetic induction intensities. In a few groups the differences were close to 20％. There were also differences within the same group. The magnetic induction intensities of the two polar surfaces were not always equal for the same magnet, and there were large differences among individual magnets.Conclusions The intensities of magnetic sources must be measured before use to ensure the consistency of magnetic induction intensities in therapeutic applications.
ABSTRACT
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.
ABSTRACT
Objective To observe the effect of pulsed electromagnetic fields (PEMFs) of different intensities on the biomechanical properties of the femur in ovariectomized rats so as to determine the intensity for the best therapeutic efficacy. Methods Fifty female Sprague-Dawley rats were randomly divided into (1) a sham-operated control group (no PEMF treatment) , (2) ovariectomized control group (no PEMF treatment) (3) ovariectomized group Ⅰ (PEMF treatment at 8 Hz and 0.77 mT intensity, 40 min daily for 30 days) (4) ovariectomized group Ⅱ (PEMF treatment at 8 Hz and 3.82 mT intensity, 40 min daily for 30 days) and (5) ovariectomized group Ⅲ( PEMF treatment at 8 Hz and 9.87 mT intensity, 40 min daily for 30 days). Except for the 10 rats of the sham-operated control group, all the others received a standard ovariectomy. Serum estradiol (E2) and the biomechanical properties of one femur (peak load, maximum displacement, maximum energy absorption, maximum stress, maximum strain and modulus of elasticity) were assessed after 30 days of PEMF treatment. Results In group Ⅱ the biomechanical properties of the femur were significantly better than in group Ⅰ or the ovariectomized control group. In groups Ⅰ and Ⅲ the biomechanical properties of the femur were not significantly better than in the sham-operated group. In group Ⅱ the biomechanical properties of the femur were significantly better than in groups Ⅰ or Ⅲ. Conclusion PEMFs at 3.82 mT can improve the biomechanical properties of the femur significantly.