PubMed · 9390103
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M Wakelkamp. 1997. Computational results may depend on personal computer processor.. https://doi.org/10.1016/s0009-9236(97)90042-4
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Improvements to an active MR tracking technique are described. Real-time position monitoring of interventional procedures can be realized by incorporating a small marker that emits an NMR signal into the tip of an interventional device, and the marker's emitted NMR signal is enhanced by use of the Overhauser phenomenon. A significant advance over prior designs has achieved by making the marker have a cylindrical shape and by confining the saturation energy to the marker's interior. The performance of the improved active marker was verified in the laboratory and in vitro. The experiments demonstrated that the marker was visible in MR images when inserted in different excised tissues, and even in air, with positive contrast and with various imaging sequences. The tissue magnetization was minimally perturbed, and the marker emitted a variable but enhanced signal in all orientations in the magnetic field. The marker can potentially be used to mark locations on the body for frameless stereotaxy or to identify inserted devices.
Radiation therapy has been used in the treatment of numerous head and neck malignancies. Unfortunately, this treatment also causes complications by increasing the morbidity to the surrounding tissues. The fabrication of a tissue bolus prosthesis is recommended to compensate for the loss of tissue and to help distribute the radiation homogeneously to the tissues. This article describes the procedures necessary for making an impression and fabricating a tissue bolus prosthesis. This custom-made prosthesis is simple, efficient, and atraumatic for the patient. Use of a tissue bolus prosthesis allows the radiation oncologist to adequately irradiate the tissues.
Sophisticated nozzle and spray-drier were newly developed. The nozzle type was that of four-phase spraying, where two liquid streams and two air streams were blown off. The spray pattern from the nozzle was of a hollow-cone type. Mean diameter of droplets in the mist was 13.2 microm in weight average in the condition of blowing at 776 g/min in air flow and 500 ml/min in liquid flow. That is, the weight-based flow ratio of air to liquid was as small as 1. 55. The geometric standard deviation of the droplet size was less than 1.65. This nozzle was still available for a concentrated suspension up to 27% solid without formation of the sludge on the orifice. Thus, fine powder with 1.99 microm in mean diameter was obtained by means of the nozzle and the spray-drier newly developed by us. These are promising for industrial production of the fine powder with low energy and high recovery.