title: Modulation of photoacoustic signal generation from metallic surfaces.
abstract: The ability to image metallic implants is important for medical applications ranging from diagnosis to therapy. Photoacoustic (PA) imaging has been recently pursued as a means to localize metallic implants in soft tissue. The work presented herein investigates different mechanisms to modulate the PA signal generated by macroscopic metallic surfaces. Wires of five different metals are tested to simulate medical implants/tools, while surface roughness is altered or physical vapor deposition (PVD) coatings are added to change the wires' overall optical absorption. PA imaging data of the wires are acquired at 970 nm. Results indicate that PA signal generation predominately occurs in a wire's metallic surface and not its aqueous surroundings. PA signal generation is similar for all metals tested, while addition of PVD coatings offers significant modulations (i.e., 4-dB enhancement and 26-dB reduction achieved) in PA signal generation. Results also suggest that PA signal increases with increasing surface roughness. Different coating and roughness schemes are then successfully utilized to generate spatial PA signal patterns. This work demonstrates the potential of surface modifications to enhance or reduce PA signal generation to permit improved PA imaging of implants/tools (i.e., providing location/orientation information) or to allow PA imaging of surrounding tissue.
authors: University of Texas MD Anderson Cancer Center, Department of Imaging Physics, Houston, TX 77054, USA.
authors: Trevor
authors: T
authors: Mitcham
authors: Kimberly
authors: K
authors: Homan
authors: Wolfgang
authors: W
authors: Frey
authors: Yun-Sheng
authors: YS
authors: Chen
authors: Stanislav
authors: S
authors: Emelianov
authors: John
authors: J
authors: Hazle
authors: Richard
authors: R
authors: Bouchard
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008670:Metals / Q000737:chemistry*; D019047:Phantoms, Imaging; D061088:Photoacoustic Techniques / Q000379:methods*; D019736:Prostheses and Implants; D012815:Signal Processing, Computer-Assisted; D013499:Surface Properties; D025321:Surgery, Computer-Assisted; D014159:Transducers
chemical_list: D008670:Metals
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