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(Color online) The schematic diagram of the TM-FT system. The HIFU transducer is driven by a combination of a signal generator and an RF power amplifier. Using a xyz translational stage, it is scanned over the probed medium that is simultaneously irradiated with modulated laser light. The intensity variations are detected using a photomultiplier tube and measured by a Network Analyzer.
(Color online) Temperature response of Pluronic ICG. The amplitude signal is recorded with the network analyzer, and the temperature is measured using a fiber optical temperature sensor.
(Color online) Experimental set-up. (a) The picture of the system. The HIFU transducer is mounted on an xyz translation stage. The source and detector fibers are placed in opposite side of the phantom to acquire fluorescence measurements in transmission mode. (b) The diagram of the transducer zoom-in view. During the HIFU scan, a localized temperature increase on the focal spot (∼1.5 mm size) is generated. As a result, the measured fluorescence signal only changes when the focal spot is on the fluorescence source.
(Color online) The point spread function measurement. (a) An optical temperature sensor is inserted in the phantom and the temperature change is recorded when the HIFU is scanned through a 5 mm × 5 mm area with 0.5 mm steps. (b) The profile shows that the FWHM of the heating spot size is 1.8 mm.
(Color online) Phantom experiment results. (a) The true size and position of inclusion is shown. (b) The position of the sources and detectors is indicated in ‘S’ and ‘D’ numbers. They are placed in opposite side of the phantom to acquire fluorescence measurements in transmission mode. (c) The reconstructed fluorescence map using conventional fluorescence tomography. Meanwhile, the scanning area is determined as indicated by dashed lines. (d) The HIFU transducer is scanned through an 8 mm × 8 mm area while fluorescence measurements are taken. (e) The fluorescence signal only significantly changes when the HIFU hot spot is scanned through the fluorescence object, which reveals the high resolution fluorophore distribution map. (f) The comparison of the experimentally measured fluorescence intensity change and those predicted by the theoretical model. The theoretical prediction is shown in solid lines, while the experimental data is plotted in triangles. (g) The normalized profiles plot across the fluorescence source shows that the size of the fluorescence source is accurately recovered.
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