To localize and monitor the blood content in tissue we developed very sensitive photoacoustical detectors. In these detectors a PVdF-layer has been used as piezo-electric material and also fibers for the illumination of the sample are integrated. The resolution is about 20 im in depth and about 50-100 im laterally. The wavelengths ofthe laser light were 532and 1064 nm. With these colors we can measure at different depths in tissue. We will report measurements on real tissue: vessels in chicken breast, in the human arm, and in test animals at various positions.
Using very sensitive photoacoustical detectors we localized and monitored the blood content in tissue. In these detectors a PVdF-layer has been used as piezo-electric material and also fibers for the illumination of the sample are integrated. The resolution is about 20micrometers in depth and about 50-100micrometers laterally. The wavelengths of the laser light were 532 and 1064 nm. With these colors we can measure at different depths in tissue. The measurements concerned blood perfusion in real tissue: vessels in chicken breast, in test animals at various positions and in the human arm.
Photo-acoustics (PA) is a technique, which can be used as the basis for non-invasive medical tomography. It is based on the absorption contrast between the biological target and the surrounding tissue and as a result of that does not suffer from strong light scattering. This fact makes PA suitable for imaging of the microvasculature in skin (532nm) or of deeper structures by using infrared light. In this paper, we present images of a vasculature cast, which was obtained by a Wistar rat and measurements on the absorption coefficient of Evans Blue.
To localize and monitor the blood content in tissue we developed a very sensitive photo-acoustical detector. PVDF has been used as piezo-electric material. In this detector also fibers for the illumination of the sample are integrated. Resolution is about 20 (m in depth and about 50-100 m laterally). We use 532 nm light. We will show how photoacoustics can be used for measuring the thickness of tissue above bone. We will also report measurements on tissue phantoms: e.g. a vessel delta from the epigastric artery branching of a Wistar rat, filled with an artificial blood-resembling absorber. The measurements have been carried out on phantoms containing vessels at several depths. Signal processing was enhanced by Fourier processing of the data.
Our goal is the development of a photo-acoustic instrument for 3D imaging of the microvascular structure in tissue, in real time. A photo-acoustic multi-element detector has been designed, which measures in reflection mode. The light source is a pulsed laser with a wavelength of 532nm and the active piezo-material is PVdF. Using a disk detector we have achieved to reconstruction 3D images with a depth and lateral resolution of 10-20 micrometers and 200 micrometers respectively. With the new probe we expect to reduce the measuring time and to sped up the signal and image processing.
To localize and monitor the blood content in tissue we developed a very sensitive double-ring photo-acoustical detector. PvdF has been used as piezo-electric material. In this detector also a fiber for illumination of the sample is integrated. This detector has the advantage that it is very sensitive in the forward direction. A ratio of FWHM to depth of 1:70 can be obtained with this detector.
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