Spring 2011 - March 18
Dept of Physics & Astronomy
University of Maine, Orono, Maine
Ronald A. Roy (EPS ’81)
Professor and Chair, Dept. of Mechanical Engineering
Augmenting biomedical imaging using the interaction of light and sound
This two-part talk focuses on the acousto-optic imaging (AOI) of optical variability in a diffusive medium — a relatively new technique based on the interaction of multiply-scattered coherent laser light with an ultrasonic field. The two waves “mix” and the light emanating from the interaction region is phase modulated at the ultrasound frequency. This technique yields information on both the optical and acoustical properties of the interaction volume, which, since the optical field is diffuse, is determined by the dimension of the ultrasonic beam. We describe a system in which a commercial ultrasound scanner was combined with a photorefractive crystal (PRC) based optical detection scheme to generate co-registered images of acoustic and optical properties of optically absorbing inclusions embedded in excised biological tissue.
The second part addresses how AO sensing can be used to monitor — in real time — lesion formation by high-intensity therapeutic ultrasound (HIFU). Here, the HIFU beam serves to both create the lesion and pump the AO response, thereby facilitating alignment of the sensing and treatment volumes and maximizing sensitivity. Results obtained with excised chicken breast show correlation between the change in AO signal level and the HIFU lesion volume.
[Work supported by the Center for Subsurface Sensing and Imaging Systems via NSF ERC award no. EEC-9986821.]
Friday, March 18, 2011
140 Bennett Hall
Refreshments are now served BEFORE the Colloquium talk
in Rm. 140 Bennett Hall at 3:00 pm