Figure 2.

Setup used for irradiation and ultrasound imaging. A) (Front view) For irradiation, the rat was positioned on a heating pad mounted to a 3-axis rotatable base. The heating pad was rotated to an angle such that the irradiation beam was centered on the tumor while minimizing exposure to the abdominopelvic region. The 1 cm water-equivalent bolus was then placed on top of the tumor region. B) (Top view) The rat was secured to the heating pad using medical tape. A 2 cm x 2 cm irradiation field size was used. C) (Front view) For imaging, the rat was positioned on the same heating pad, oriented parallel to the floor such that the tumor was facing up. A custom designed water bath was used to separate the transducer from the gel while still being continuously coupled to the tumor, so that the mechanical translation of the transducer would not displace the gel causing decoupling and introducing air bubbles. D) (Side view) The transducer was mechanically translated in the elevational dimension for 2 cm for each scan.