Fig. 5.

Simulated phantom of curved bone of (a) constant 4-mm thickness and (b) varying thickness with horizontal target located at 30 mm depth. The acoustic sensor is located at 0 mm depth. Corresponding simulated photoacoustic images, demonstrating that as bone thickness changes from (c) constant to (d) varied, the target location changes, which would complicate vessel localization. (d) Simulated phantom containing skull from a segmented CT image with two parallel targets and (e) corresponding photoacoustic image, indicating that the challenge with the depth shifts could be overcome if more than one target is present in the image.