Systems for research and development in medical ultrasound imaging.

The system requirements of engineers conducting research and development into new ultrasonic methods for medical applications are reported. The design criteria for these systems are explained together with a review of what is currently available.

[Ultrasound hard tissue detection for registration in orthopedics and traumatology]. / Ultraschall-Hartgewebedetektion zur Registrierung in der Orthopädie und Traumatologie.

The application of x-ray diagnostics for intraoperative navigation and for registration of hard tissue structures is restrained due to high radiation loads and the not given real time ability. Previous approaches with conventional ultrasonic imaging are only interactively applicable due to the high information content of soft tissue optimised B-mode-images. A pure image processing does not allow an automatic identification of individual structures, so that this must be done by the physician. To decrease the high expense of time, this report presents a concept for an adapted chain of rf-signal processing as well as an ultrasonic system for the contrast-enhanced representation of tissue borders. The system permits an exact measurement of the body geometry, which is demonstrated by determining the position of the pelvis entry plane.

[Ultrasound control of thermal tissue therapy]. / Ultraschall-Kontrolle Thermischer Tumor Therapien.

As alternatives to surgical resection and/or supportive to radio- or chemo-therapy of tumors and metastases minimal invasive interstitial thermal treatment procedures by which the tissue is heated up locally to temperatures up to 100 degrees C are used. However beside nuclear magnetic resonance tomography there is no economical, by routine applicable procedure for non invasive therapy control at present disposal. In this work the possibility of non invasive control of thermal therapies by means of temporal and spectral analysis of radio frequency ultrasound signals are evaluated. Two different ultrasonic procedures, the first beeing based on the analysis of local modifications in the time of flight of the ultrasound signal for determination of the temperature distribution in the tissue, the second beeing based on the physical attenuation characteristics of biological tissue and their dependence on the tissue structure are proposed and evaluated for therapy control. With in vitro experiments the possibilities and limitations of both procedures and preliminary results of a prototype control system are demonstrated.

Spectroscopic and morphologic characterization of the dentin/ adhesive interface.

The potential environmental risks associated with mercury release have forced many European countries to ban the use of dental amalgam. Alternative materials such as composite resins do not provide the clinical function for the length of time characteristically associated with dental amalgam. The weak link in the composite restoration is the dentin/adhesive bond. The purpose of this study was to correlate morphologic characterization of the dentin/adhesive bond with chemical analyses using micro-Fourier transform infrared and micro-Raman spectroscopy. A commercial dental adhesive was placed on dentin substrates cut from extracted, unerupted human third molars. Sections of the dentin/adhesive interface were investigated using infrared radiation produced at the Aladdin synchrotron source; visible radiation from a Kr+ laser was used for the micro-Raman spectroscopy. Sections of the dentin/adhesive interface, differentially stained to identify protein, mineral, and adhesive, were examined using light microscopy. Due to its limited spatial resolution and the unknown sample thickness the infrared results cannot be used quantitatively in determining the extent of diffusion. The results from the micro-Raman spectroscopy and light microscopy indicate exposed protein at the dentin/adhesive interface. Using a laser that reduces background fluorescence, the micro-Raman spectroscopy provides quantitative chemical and morphologic information on the dentin/adhesive interface. The staining procedure is sensitive to sites of pure protein and thus, complements the Raman results. © 1999 Society of Photo-Optical Instrumentation Engineers.