title: Ultrasound modulated optical tomography: Young's modulus of the insonified region from measurement of natural frequency of vibration.
abstract: We demonstrate a method to recover the Young's modulus (E) of a tissue-mimicking phantom from measurements of ultrasound modulated optical tomography (UMOT). The object is insonified by a dual-beam, confocal ultrasound transducer (US) oscillating at frequencies f₀ and f₀ + Δf and the variation of modulation depth (M) in the autocorrelation of light traversed through the focal region of the US transducer against Δf is measured. From the dominant peaks observed in the above variation, the natural frequencies of the insonified region associated with the vibration along the US transducer axis are deduced. A consequence of the above resonance is that the speckle fluctuation at the resonance frequency has a higher signal-to-noise to ratio (SNR). From these natural frequencies and the associated eigenspectrum of the oscillating object, Young's modulus (E) of the material in the focal region is recovered. The working of this method is confirmed by recovering E in the case of three tissue-mimicking phantoms of different elastic modulus values.
authors: Department of Instrumentation and Applied physics, Indian Institute of Science, Bangalore-560012, India.
authors: R Sriram
authors: RS
authors: Chandran
authors: Debasish
authors: D
authors: Roy
authors: Rajan
authors: R
authors: Kanhirodan
authors: Ram Mohan
authors: RM
authors: Vasu
authors: C Usha
authors: CU
authors: Devi
mesh_terms: D055119:Elastic Modulus / Q000502:physiology*; D004560:Electricity; D009391:Nephelometry and Turbidimetry; D019047:Phantoms, Imaging; D041622:Tomography, Optical / Q000379:methods*; D014160:Transducers, Pressure; D014465:Ultrasonics / Q000379:methods*; D014732:Vibration