Safety Study of Implant Wearers in MRI RF Field Environment / 中国医疗器械杂志

The complex electromagnetic field environments in magnetic resonance imaging system(MRI) can have a significant impact on patients carrying implants, the RF heating problems being particularly important. To ensure the safety of the patients, it is necessary to understand the distribution of tissue temperature in the MRI environment and its changes over time. Based on the analysis of tissue temperature rise in MRI, this paper constructs a bird cage coil for generating RF field in MRI system, and constructs ASTM standard/improved phantom and single-cavity pacemaker finite element models, use time-domain finite difference (FDTD) to simulate. Firstly, the correctness of the simulation software and simulation method was validated according to the method of ISO. Then the distribution of the electric field, SAR and temperature field and the temperature change with time were calculated in the environment of 64 MHz, 2 W/kg. The difference in temperature rise with blood heat exchange and no blood heat exchange (standard/improved phantom) was specifically compared. The simulation results show that there are electric field and SAR hotspots near the electrode tip, the wire tail and the case of pacemaker. There are high SAR values on both sides of the phantom, and the shorter the distance from the coil, the higher the SAR. The temperature field distribution is similar to the SAR distribution; the temperature is higher in the area around the end of the wire and the case of pacemaker because the heat accumulation is higher around this area. At the same time, blood heat exchange can reduce the temperature rise to a certain extent.

Verification of the new proposed version of pyrogen result judgment algorithm / 中国药学杂志

OBJECTIVE: To verify the new proposd version of pyrogen result judgment algorithm (NPRJA) and validate practicality, accuracy and reliability. METHODS: Six hundred and fifty-four batches of pyrogen test data from our laboratory in near three years were used; 3 648 rabbit body temperature fluctuations qualified in preview were statistically analyzed. Only single rabbit having lever was used to judge the pyrogen qualified or not; using logic anlysis method determined the NPRJA. RESULTS: According to the existing Chinese Pharmacopoeia volume III, suspicious rate of pyrogenic results was 28.0%, but the suspicious rate was only 10.4% in NPRJA. The new model can reduce over 60% of the repeat test. However, all failed samples were not leaked in new determiner. In preflight warm qualified rabbits, the temperature fluctuations were rather more than reach 0.4℃ within the first 3 h, they had more than 8% in whole rabbits. CONCLUSION: In pyrogen test rabbit own body temperature appears fluctuation, single rabbit warming≥ 0.6℃ serves as one of the criteria for re-examination of the sample, its results will lead to raising re-examination rate! The new proposed version of pyrogen result judgment algorithm was used to threshold of the sum of temperature rise of all tested rabbits, that not only guarantees the no changing of accuracy in existing present pyrogen test results, also significantly reduces the amount of animals and experimental repetitions. Thereby reducing the amount of experimental and labor costs. Meanwhile, it might be convenient and practical, as will as a worthy utilization and promoting patterns.

Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

OBJECTIVES: Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). MATERIALS AND METHODS: Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. RESULTS: The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05). CONCLUSIONS: Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

Changing Transmission Pattern of Plasmodium vivax Malaria in the Republic of Korea: Relationship with Climate Change

Plasmodium vivax malaria has occurred annually in the Republic of Korea (ROK) since its re-emergence in 1993. P. vivax malaria in ROK has been strongly influenced by infected mosquitoes originating from the Democratic People's Republic of Korea. Korean P. vivax malaria has shown typical characteristics of unstable malaria transmitted only during the summer season, and displays short and long incubation periods. The changing pattern of the transmission period can be predicted by analyzing the seasonal characteristics of early primary attack cases with a short incubation period. Such cases began to gradually occur earlier in the 1990s after the re-emergence. Most of the malaria cases after mid-August are presumed to be early primary attack, short incubation period cases. Only primary transmission was possible until the early 2000s, whereas up to fourth or fifth transmission occurred in the mid-2000s. The results indicate that the length of transmission period has been gradually extending, which may be ascribed to a climate change-mediated temperature rise. Malaria and climate data should be integrated to analyze and predict the influence of climate change on malaria occurrence in ROK.

Aumento de la temperatura intracámara pulpar durante el blanqueamiento con sistemas activados por luz: revisión de la literatura / Temperature increase intracameral pulp during bleaching with light-activated systems: review of the literature

Son varias las fuentes de energía utilizadas para acelerar la descomposición del peróxido de hidrógeno durante el blanqueamiento realizado en el consultorio. Durante su aplicación, los sistemas de blanqueamiento dental que utilizan fuentes de energía, aumentan la temperatura de los tejidos dentarios. Existen evidencias de que el aumento de la temperatura intracámara pulpar puede causar daño a este tejido. Este trabajo tuvo por objetivo presentar a través de una revisión de la literatura los diferentes tipos de luz utilizados para blanqueamiento y el calentamiento intracámara pulpar generado por estos. El aumento de temperatura intracámara pulpar crítico es considerado de 5,5º C. En estudios in vitro varios son los sistemas y combinaciones de tiempo que llegan o pasan esta temperatura. Antes de la utilización de estos sistemas el odontólogo debe conocer los riesgos existentes y leer las instrucciones de los fabricantes

To accelerate the decomposition of hydrogen peroxide during the in-office bleaching process, various energy sources can be used. During the application of these energy systems, an increase of temperature in teeth tissue has been reported. The temperature rise in the pulp might be harmful to this tissue. The objective of this work was to present through a literature review the different lights for an in-office bleaching and the resultant intrapulpal temperature rise produced by these lights. The critical temperature rise in pulp chamber is considered to be 5.5º C. On in vitro studies there are many systems and time combinations that achieved or passed this critical limit. Before the use of any energy source for the in- office bleaching, the dentist should be concerned about the existing risk and must read the manufacturer's instructions

The relation between local temperature rise and therapeutic effects of focused ultrasound on chronic cervicitis / 重庆医科大学学报

Objective:To explore the relation between therapeutic effects of focused ultrasound(FU)on chronic cervicitis and local temperature rise.Methods:132 cases of chronic cervicitis were treated by FU and local temperature rise was measured. 120 patients were followed up regularly for the following 3 months to observe therapeutic effects and adverse effects.Results: The overall effective rate of FU in treatment of chronic cervicitis unitarily was 97.5%.When the temperature of targeted tissue immediately after FU exposure was between 40℃and 43℃,the therapeutic effects tended to he satisfactory(98.33%)with little adverse effects.Conclusion:A satisfactory therapeutic efficacy could be achieved with single session FU in treatment of chronic cervicitis.And local temperature rise measurement,as a quantification method,is helpful to improve the therapeutic effects.