Examples of light attenuation signals caused by the bubble cloud generated by histotripsy pulses using different pulse parameters. The axes for the wave form are the same for each row and shown on the right. Arrows indicate the arrival of the pulse. The pulse parameters and corresponding light attenuation results are listed in Table I.
Images of the bubble cloud generated in free water created by a single histotripsy pulse at different pulse durations. The histotripsy pulse was delivered from the left to the right of each image. The overall size of the bubble cloud increased with increasing pulse duration. The ruler on the top of each image has markings of on the right side and on the left.
Example of the light attenuation signal caused by a bubble cloud, recorded as the photodiode voltage output. The bubble cloud was generated by a three-cycle pulse at a tissue-water interface with 98%–100% gas concentration. The left arrow below “Attenuation Duration” indicates the arrival of the histotripsy pulse at the transducer focus where the laser beam was projected. The insert is an expanded view (expanded in the horizontal direction and compressed in the vertical) of the artifact in the light attenuation signal during the histotripsy pulse, which tracks the pulse wave form.
Acoustic pressure wave form of a ten-cycle histotripsy pulse in water at the transducer focus. For this pulse, the peak rarefactional pressure was and the peak compressional pressure was .
Diagram of the experimental arrangement for bubble cloud monitoring at a tissue-water interface using an optical attenuation method. Light source and camera (in dashed circle) are setup for high speed imaging in water. However, at a tissue-water interface, the light source was blocked by the tissue, and the imaging could not be used with the optical attenuation detection system.
Pulse parameters used in Fig. 1 and corresponding light attenuation results at a tissue-water interface.
Attenuation durations generated by a single pulse to study the effects of the gas concentrations and a tissue boundary.
Peak attenuation levels generated by a single pulse to study the effects of the gas concentrations and a tissue boundary.
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