Georg Schmitz

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Ultrasound is an established therapy method for bone fracture healing, hyperthermia and the ablation of solid tumors. In this new emerging field, ultrasound is further used for microbubble-enhanced drug delivery, gene therapy, sonoporation and thrombolysis. To study selected therapeutic effects in defined experimental conditions, in vitro setups are(More)
In fast pulse-echo diagnostic ultrasound imaging the acquisition time for a single image is crucial. This time depends significantly on the number of sequentially emitted sound waves. For fewer wave emissions the inverse scattering problem is increasingly ill-posed. In this contribution we establish and investigate a solution based on compressive sensing(More)
Photoacoustics (PA) is a new imaging modality based on the generation of ultrasound due to laser irradiation. Instead of commonly used Q-switched Nd:YAG lasers the application of pulsed laser diodes as light sources for photoacoustic imaging is proposed. The high pulse repetition frequency of laser diodes enables the usage of coded excitation schemes for(More)
This paper discusses various interactions between ultrasound, phospholipid monolayer-coated gas bubbles, phospholipid bilayer vesicles, and cells. The paper begins with a review of microbubble physics models, developed to describe microbubble dynamic behavior in the presence of ultrasound, and follows this with a discussion of how such models can be used to(More)
Q-switched Nd:YAG lasers are commonly used as light sources for photoacoustic imaging. However, laser diodes are attractive as an alternative to Nd:YAG lasers because they are less expensive and more compact. Although laser diodes deliver about three orders of magnitude less light pulse energy than Nd:YAG lasers (tens of microjoules compared with tens of(More)
We present a method to speed up the acquisition of multispectral photoacoustic data sets by using unipolar orthogonal Golay codes as excitation sequences for the irradiation system. Multispectral photoacoustic coded excitation (MS-PACE) allows acquiring photoacoustic data sets for two irradiation wavelengths simultaneously and separating them afterwards,(More)
Photoacoustic (PA) imaging is an imaging modality based on the generation of ultrasound using laser irradiation. Pulsed laser diodes are an attractive alternative to Q-switched Nd:YAG lasers since they are cheaper and handier. As acoustic time-of-flight limits the pulse repetition frequency (PRF) for averaging, photoacoustic coded excitation (PACE) can be(More)
Ultrasound contrast agents consist of gas-filled microbubbles stabilized by a shell. Under ultrasound insonification, these bubbles oscillate nonlinearly with resonance frequencies being well within the diagnostic range. Currently, different detection methods are proposed, often with a heuristic reasoning based on the bubble nonlinearity being modeled by a(More)
In current methods for contrast-enhanced ultrasound such as phase inversion (PI), the achievable contrast-to-tissue ratio (CTR) is limited by the nonlinear propagation of sound in tissue. A fundamental difference between sound propagation nonlinearity and contrast agent oscillation nonlinearity, however, is the different scale of the nonlinear memory of(More)
A procedure for the electro-acoustical characterization in air of cMUTs is reported. First, the measured input electrical impedance of the transducer is used to calculate the transducer parameters at different bias voltages by fitting it with the Mason model. Then, the single membrane equivalent circuit can be calculated. Second, the cMUT impulse response(More)