128-channel laser optoacoustic imaging system (LOIS-128)for breast cancer diagnostics

We have designed, fabricated and tested a new 128-channel laser optoacoustic imaging system (LOIS-128) for cancer diagnostics consisting of an acoustic probe with 128 PVDF transducers, a digital signal processor with 128 independent channels, and software for reconstruction of optoacoustic images. The system was capable of continuous planar imaging (at rates up to 1 Hz) of small (less than 1 cm) tumors at depths over 6 cm. The directivity of the optoacoustic transducers used in LOIS-128 assured that signal detection at all angles within a narrow imaging slice was at least 40% of the maximal signal. The signal detection was better than 70% of the maximum for about 75% of the image in the image slice and close to zero for signals coming from out of the image slice. LOIS-128 could image high-aspect-ratio objects with about 0.5 mm resolution. Finally, with the designed image reconstruction algorithm we were able to estimate absorption coefficients for test objects with accuracy of at least 5%.