Figure 6.

Thermoacoustic images of a) saline-encapsulated PS hollow beads (prepared from the 23.1% saline solution), b) DI-water-encapsulated hollow beads, and c) DI water alone contained in a 6-mm (inner diameter) LDPE tube, where “max” indicates the peak signal value in an arbitrary unit of the reconstructed image and “avg.” indicates the average signal value calculated over the entire square area shown. d) Normalized signal intensity cross-section of images in (a–c), taken at the direction of the x-axis. Signal intensities were normalized to the peak value in (a) for saline-encapsulated hollow beads.