A training phantom for ultrasound-guided boiling histotripsy therapy

Abstract

Boiling histotripsy (BH) uses millisecond-long focused ultrasound pulses with shocks to mechanically disrupt targeted tissue under real-time ultrasound monitoring. However, adipose tissue and ribs can interfere with BH therapy through aberration, absorption, and diffraction. Here we introduce a robust abdominal wall phantom that includes fat, muscle, and rib layers for demonstrating the use of BH and investigating the impact of anatomic structures on treatment success. The skin is a silicone sheet; the fat and muscle layers are poly-vinyl alcohol phantoms with irregular-shaped walls; the ribs are 3D-printed sections from a human model anatomically relevant to liver or kidney treatments. The target is a transparent alginate or polyacrylamide gel that allows visualization of the lesion. The pieces are assembled in a water-filled container providing coupling between layers and allowing components to be shifted in position relative to the transducer. A BH transducer (1.2 MHz, 12.5 cm focal length, f# = 1) containing an imaging probe in its central opening was used for initial phantom assessment. Preliminary results show that each layer impacts the beam in ways similar to observations from in vivo and ex vivo experiments. [Work supported by NSBRI through NASA NCC 9-58, NIH RO1EB007643, K01EB015745, and K01DK104854.]