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These techniques are known as Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) [31] [32] and Ultrasound guided Focused Ultrasound Surgery (USgFUS) respectively. [ 1 ] [ 33 ] MRgFUS is a 3D imaging technique which features high soft tissue contrast and provides information about temperature, thus allowing to monitor ablation.
Ultrasound can ablate tumors or other tissue non-invasively. [4] This is accomplished using a technique known as high intensity focused ultrasound (HIFU), also called focused ultrasound surgery. This procedure uses generally lower frequencies than medical diagnostic ultrasound (250–2000 kHz), but significantly higher time-averaged intensities.
Ultrasonic sonicators generate ultrasound waves, which is a longitudinal compression wave, by converting electrical energy into mechanical energy by deformation of piezoelectric crystals in response to an electric field. [1] [3] The frequency of the waves generated by this method can range from 20 kHz up to 3 MHz. [3]
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
The importance of the schlieren imaging technique is prominent in High Intensity Focused Ultrasound (HIFU) research and development. [5] Advantages of schlieren imaging include: Free field: the investigated acoustic field is not distorted by the measuring probe. High intensity measurements: the method is compatible with high acoustic intensities.
The ultrasonic devices achieve high directivity by modulating audible sound onto high frequency ultrasound. The higher frequency sound waves have a shorter wavelength and thus don't spread out as rapidly. For this reason, the resulting directivity of these devices is far higher than physically possible with any loudspeaker system. However, they ...
The frequency content of the generated ultrasound is partially determined by the frequency content of the laser pulses with shorter pulses giving higher frequencies. For very high frequency generation (up to 100sGHz) femtosecond lasers are used often in a pump-probe configuration with the detection system (see picosecond ultrasonics ).
Photoacoustic imaging or optoacoustic imaging is a biomedical imaging modality based on the photoacoustic effect.Non-ionizing laser pulses are delivered into biological tissues and part of the energy will be absorbed and converted into heat, leading to transient thermoelastic expansion and thus wideband (i.e. MHz) ultrasonic emission.