Biomedical subjects
M Brünner
Publications and source records attributed to M Brünner.
Visualization and registration of three-dimensional E-field distributions in annual-phased-array applicators.
A testing system is presented allowing registration, digitization, and evaluation of three-dimensional power distributions rendered by annular-phased-array applicators in homogeneous liquid media. The system is based on a lamp phantom originally developed to visualize power distributions. Now the brightness distribution is registered via a charge-coupled device camera and transferred to a PC-based evaluation system outside the shielding room. An appropriate mechanical coupling of camera and sensor matrix probing the phantom was built in order to keep optical image conditions constant under movement. For visualization and evaluation commercially customized software was employed. The evaluation of the system shows the linearity between sensor signal and power density magnitude to be sufficient for evaluation and graphical representation of three-dimensional data sets. In a first practical application the testing system was employed to evaluate dependencies of power distributions as a function of frequency and phase settings on temperatures and, subsequently, the relevance of those results for clinical hyperthermia in a SIGMA-60 applicator (BSD-2000 system). Now, the system is ready to evaluate more complex multiantenna array applicators like the SIGMA-Eye applicator. The measuring system is particularly suitable for a fast comparison of APA applicators applied for a homogeneous medium. Implications for heterogeneous structures (like in patients) are then possible via modeling calculations.
[Pollution of operating room air by anesthetic gases in relation to the air conditioning method and anesthesia techniques].
Volatile anesthetics are suspected to cause various health risks even in subnarcotic concentrations (hepatotoxicity, mutagenicity, teratogenicity). Yet only for halothane a limit (MAK-value = 5 ppm) has been established for the entire FRG. In addition, in 1991 Hamburg and Schleswig-Holstein defined preliminary limits for isoflurane, enflurane and nitrous oxide. We analysed the pollution of operating-room air by narcotic gases in 20 hospitals of Niedersachsen. In several cases limits have been exceeded evidently. Reasons for high concentrations were: insufficient room ventilation, defective air-conditioning plants, technical defects (leakage) and high gas emission due to special techniques in anesthesia (bronchoscopy). In order to take care of personnel-health air concentration of anesthetic gases should be kept as low as possible by the help of sufficient room ventilation avoiding unnecessary emissions.