title: Characterizing an agar/gelatin phantom for image guided dosing and feedback control of high-intensity focused ultrasound.
abstract: The temperature dependence of an agar/gelatin phantom was evaluated. The purpose was to predict the material property response to high-intensity focused ultrasound (HIFU) for developing ultrasound guided dosing and targeting feedback. Changes in attenuation, sound speed, shear modulus and thermal properties with temperature were examined from 20°C to 70°C for 3 weeks post-manufacture. The attenuation decreased with temperature by a power factor of 0.15. Thermal conductivity, diffusivity and specific heat all increased linearly with temperature for a total change of approximately 16%, 10% and 6%, respectively. Sound speed had a parabolic dependence on temperature similar to that of water. Initially, the shear modulus irreversibly declined with even a slight increase in temperature. Over time, the gel maintained its room temperature shear modulus with moderate heating. A stable phantom was achieved within 2 weeks post-manufacture that possessed quasi-reversible material properties up to nearly 55°C.
authors.affiliation: Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA. mrbean@u.washington.edu
authors.forename: Barbrina
authors.initials: B
authors.lastname: Dunmire
authors.forename: John C
authors.initials: JC
authors.lastname: Kucewicz
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Mitchell
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Crum
authors.forename: K Michael
authors.initials: KM
authors.lastname: Sekins
mesh_terms: D000362:Agar / Q000737:chemistry / Q000528:radiation effects*; D019544:Equipment Failure Analysis; D005246:Feedback; D005782:Gels / Q000737:chemistry / Q000528:radiation effects; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D008422:Materials Testing; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods*
chemical_list: D005782:Gels; D000362:Agar