Millimeter wave exposure induces apoptosis in human melanoma A375 cells / 南方医科大学学报

OBJECTIVE@#To investigate the effects of millimeter wave (MMW) exposure on apoptosis of human melanoma A375 cells and explore the mechanisms.@*METHODS@#Through electromagnetic field calculation we simulated MMW exposure in cells and calculated the specific absorption rate (SAR). The optimal irradiation parameters were determined according to the uniformity and intensity of the SAR. A375 cells were then exposed to MMV for 15, 30, 60, or 90 min, with or without pretreatment with the caspase-3 inhibitor AC-DEVD-fmk (10 μmol/L) for 1 h at 90 min before the exposure. CCK-8 assay was used to assess the changes in the viability and Annexin-V/ PI staining was used to detect the apoptosis of the cells following the exposures; Western blotting was used to detect the expression of caspase-3 in the cells.@*RESULTS@#The results of electromagnetic field calculation showed that for optimal MMV exposure, the incident field needed to be perpendicular to the bottom of the plastic Petri dish with the antenna placed below the dish. CCk-8 assay showed that MMW exposure significantly inhibited the cell viability in a time-dependent manner ( < 0.05); exposures for 15, 30, 60, and 90 min all resulted in significantly increased apoptosis of the cells ( < 0.05). The cells with MMW exposure showed significantly increased expression of caspase-3. The inhibitory effect of MMW on the cell viability was antagonized significantly by pretreatment of the cells with AC-DEVD-fmk ( < 0.05), which increased the cell viability rate from (36.7±0.09)% to (59.8±0.06)% ( < 0.05).@*CONCLUSIONS@#35.2 GHz millimeter wave irradiation induces apoptosis in A375 cells by activating the caspase-3 protein.

Comparisons of the specific absorption rate in 3.0T MR brain examination / 实用放射学杂志

Objective To investigate the specific absorption rate (SAR)in 3.0T MR brain examination.Methods All 280 patients underwent 3 .0 MR brain examination.And the patients were divided into three groups:a group of 0-3 years old without hands intersection, inluding 40 cases through conventional MRI examination,40 cases through MRA,as well as 40 cases through DWI;a group of more than 20 years old without hands intersection,including 40 cases through conventional MRI examination,40 cases through MRA,as well as 40 cases through DWI;a group of more than 20 years old with hands intersection,consisting of 40 cases through MRA.The SAR values of each group were recorded,respectively.And the independent samples t test was used to compare statistical difference of different SAR values between groups.Results Compared the group of 0-3 years old without hands intersection and the group of more than 20 years old without hands intersection,the SAR values of all six sequences in front group were significantly higher than that those in latter one,but not exceed the safety standard of 3 w/kg in the United States FDA.There was no significant statistical differences in the SAR values of two groups which more than 20 years old with hands intersection or not (P>0.05).Conclusion The SAR values of each sequence in the group of 0-3 years old without hands intersection were significantly higher than those in the group of more than 20 years old without hands intersection,but in a safe and reasonable range.The brain scanning with two hands intersect of 20 years old and above,and there was no significant increase on the SAR values in the brain examination of the group of more than 20 years old with hands intersection.So it is of great significance to guide the daily work,settle doubts and improve success rates of the MR examination.

Comparisons of the specific absorption rate in 3.0T MR brain examination / 实用放射学杂志

Objective To investigate the specific absorption rate (SAR)in 3.0T MR brain examination.Methods All 280 patients underwent 3 .0 MR brain examination.And the patients were divided into three groups:a group of 0-3 years old without hands intersection, inluding 40 cases through conventional MRI examination,40 cases through MRA,as well as 40 cases through DWI;a group of more than 20 years old without hands intersection,including 40 cases through conventional MRI examination,40 cases through MRA,as well as 40 cases through DWI;a group of more than 20 years old with hands intersection,consisting of 40 cases through MRA.The SAR values of each group were recorded,respectively.And the independent samples t test was used to compare statistical difference of different SAR values between groups.Results Compared the group of 0-3 years old without hands intersection and the group of more than 20 years old without hands intersection,the SAR values of all six sequences in front group were significantly higher than that those in latter one,but not exceed the safety standard of 3 w/kg in the United States FDA.There was no significant statistical differences in the SAR values of two groups which more than 20 years old with hands intersection or not (P>0.05).Conclusion The SAR values of each sequence in the group of 0-3 years old without hands intersection were significantly higher than those in the group of more than 20 years old without hands intersection,but in a safe and reasonable range.The brain scanning with two hands intersect of 20 years old and above,and there was no significant increase on the SAR values in the brain examination of the group of more than 20 years old with hands intersection.So it is of great significance to guide the daily work,settle doubts and improve success rates of the MR examination.

Specific absorption rate variation in a brain phantom due to exposure by a 3G mobile phone: Problems in dosimetry.

A specific absorption rate (SAR) measurements system has been developed for compliance testing of personal mobile phone in a brain phantom material contained in a Perspex box. The volume of the box has been chosen corresponding to the volume of a small rat and illuminated by a 3G mobile phone frequency (1718.5 MHz), and the emitted radiation directed toward brain phantom .The induced fields in the phantom material are measured. Set up to lift the plane carrying the mobile phone is run by a pulley whose motion is controlled by a stepper motor. The platform is made to move at a pre-determined rate of 2o per min limited up to 20o. The measured data for induced fields in various locations are used to compute corresponding SAR values and inter comparison obtained. These data are also compared with those when the mobile phone is placed horizontally with respect to the position of the animal. The SAR data is also experimentally obtained by measuring a rise in temperature due to this mobile exposures and data compared with those obtained in the previous set. To seek a comparison with the safety criteria same set of measurements are performed in 10 g phantom material contained in a cubical box. These results are higher than those obtained with the knowledge of induced field measurements. It is concluded that SAR values are sensitive to the angular position of the moving platform and are well below the safety criteria prescribed for human exposure. The data are suggestive of having a fresh look to understand the mode of electromagnetic field -bio interaction.

Experimental study of a novel radiofrequency ablation system / 中华物理医学与康复杂志

Objective To determine the power-time-ablation scope correlogram of a water-cooled single needle electrode radiofrequency (RF) ablation system and to establish a theoretical basis for its practical application.Methods RF ablations were performed using a water-cooled single needle electrode radiofrequency ablation system developed by the authors using fresh ox liver as well as liver and muscles of healthy adult New Zealand white rabbits.The temperature of the ablation area was monitored using a multichannel thermometric system.The maximum ablation scope was determined by detecting the rim at which the temperature was no less than 50 °C.The specific absorption rate (SAR) of the isolated liver tissue was calculated.Results In the treatment voltage range of 100-130V,the process was smooth and steady.No impedance variation was obvious.The maximum diameter of a single ablation was 51 cm.With the treatment voltage at 140-170 V,a larger ablation area could be reached in less time,but eventually the impedance began to increase while the ablation area was no longer expanded.When the treatment voltage reached the range of 180-200 V the impedance almost always increased rapidly out of limits,and the treatment system stopped automatically.The measured SAR value was consistent with the theoretical value.Pathology confirmed that both liver tissue and muscle tissue manifested typical coagulative necrosis.Conclusions The power amplifier,cooling,thermometric and control sections of the RF ablation system worked stably,and the practical ablation effect met the design and clinical treatment requirements.