Shear wave dispersion ultrasound vibrometry of gel dosimetry phantoms.

Abstract

Shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave speed to locally estimate the material properties or tissue. Shear waves were created using a mechanical shaker and pulsed radiation force. Using the information from the phase one can estimate the shear velocity. A theoretical Voigt model allows us to find, at different frequencies (100–400 Hz), the viscosity and shear elasticity of the polymer gel dosimeter. The aim of this work was to perform the SDUV and mechanical vibrometry techniques to study the viscoelastic properties of absorbed dose phantoms. The experiments were performed using five phantoms of different absorbed doses varying 10 up to 50 Gy, while a nonirradiated phantom was kept as a control. The SDUV technique was performed using a pulsed radiation force to vibrate the gel provide by a confocal transducer with a focal depth of 70 mm, nominal frequency of 3 MHz. For the mechanical vibrometry and SDUV experiments, shear wave motion measurements were made with a commercial ultrasound machine with a research using a 10 MHz linear array transducer. The quantitative elasticity and viscosity results for these two experiments were compared.