Focused Ultrasound Effects on Osteosarcoma Cell Lines
Figure 2
Thermal and Acoustic calibrations: (a) Target V-setup model used in simulations with PZFlex® software. The spot in each dotted red line shows where the thermocouple was placed during the thermal calibration; (b) Thermal map obtained from simulation:49 W/cm2 irradiated for 10 s produce a 40.7°C hot spot, localized inside the polystyrene 24-well bottom. (c) Acoustic graphs. Following the theory described by Laugier [12], along the acoustic axis the pressure decays with an exponential trend is given by: where α is the attenuation coefficient, the pressure at the reference distance, p the pressure at the desired distance and z the difference between reference and desired distance. “Cell/medium interface” is the positive pressure peak measured by hydrophone at the interface agar-water inside the well during a 10 s sonication with an acoustics intensity range 31.3-38.9 W/cm2. “Brain”, “Breast”, “Muscle” and “Liver” are the estimated value at the top of the well for an equivalent relative volume of homogeneous tissue crossed. The estimated curve for water has not been shown since it was essentially overlapping with the experimental curve. The α values (dB/Mhz·cm) used were: water = 0.0022; brain = 0.6; breast = 0.75; liver = 0.5; muscle = 1.09 (Culjat, et al. 2010); (d) thermal damage of the polystyrene layer at the bottom of a 24-well multiwell plate (arrows). The US focus was placed inside the well, 1 mm from the bottom. Starting from left, the first three wells were treated with the same acoustic energy, while the last remained untreated. Even the lowest acoustic energy adopted in this study resulted in a visible damage of the polystyrene.