Low-cost ultrasound and optical gelatin-based phantoms

In this study, a low-cost procedure using evaporated milk is followed to make a gelatin-based phantom with ultrasound and optical properties close to soft tissues. To find out the effect of concentrations of gelatin and evaporated milk on the ultrasound properties, we first made two sets of phantoms. The first set was made by mixing different amounts of gelatin with deionized water (no evaporated milk in this set), while in the second set, evaporated milk concentration was changed (constant gelatin concentration). We measured the ultrasound attenuation of these phantoms at low and high frequency ranges and show that when the gelatin concentration is kept at 5 %, the ultrasound attenuation can vary from 0.4 to 0.6 dB/MHz/cm as the evaporated milk concentration increases from 20 % to 50 %. After getting some idea about the proper concentrations of evaporated milk and gelatin on ultrasound properties, n-propanol alcohol, glass microspheres, and Germall plus preservative were added to our recipe. We then measured the optical properties of the resulted phantom. A diffuse optical tomography system (DOT) was employed for this purpose to measure the optical absorption and reduced scattering coefficients of our phantom at four different wavelengths.