A Short Study Report For Phantom Investigation

1. Polyvinyl Alcohol Phantoms (Polyvinyl alcohol gels) Polyvinyl alcohol cryogel (PVA-C) is a typical tissue-mimicking material for ultrasound imaging. It is formed from PVA solution undergoing some freezethaw (F/T) cycles. As the optical and mechanical properties change with the number of F/T cycle, certain requirements, like the scattering coefficient and absorption coefficient, for the phantom can be achieved. This phantom can be used in a permanent way under humidity-controlled conditions. PVA can be obtained from Sigma-Aldrich (catalog number 36 314-6) [5], Acros organics (Geel, Belgium) [2] or Airvol Grade 165 PVA powder (Air Products and Chemicals, Inc; Allentown, PA) [6]. Detailed construction process is discussed in [2]. The brief idea is shown below: 1) 5% or 8% by weight PVA are dissolved in distilled water. And this solution is heated for about 7 hours at the temperature of 93 to 95 degree Celsius. 2) The PVA solution is cooled to -25 to -20 degree Celsius for about 12 hours. Then, the solution will warm back to room temperature in a continuous way for another 12 hours. If needed, this F/T cycle can be repeated for several times. Without the addition of dimethyl sufoxide (DMSO), the scattering coefficient will increase with each cycle and the phantom will be stiffer, too. 3) Brain Mold is prepared using Colin27 data set. 4) Approximating the live Brain Texture. (Useful data from [2]: 6% PVA solution at 1 FTC is similar to palpating the surface of a live brain and 4% PVA at 3FTC as being similar to palpating a low-grade gliomas.) 5) Implants for registration and image guidance are included.