title: Evaluation of tissue mimicking quality of tofu for biomedical ultrasound.
abstract: The tissue mimicking quality of tofu has been evaluated in terms of acoustic properties and acousto/thermal conversion as functions of frequency and diffraction corrected intensity over the 2 MHz to 18 MHz range using three unfocussed transducers with center frequencies of 5 MHz, 10 MHz and 15 MHz. The density and acoustic velocity were close to the American Institute of Ultrasound in Medicine (AIUM) recommended values for the soft tissue, however, the attenuation increases nonlinearly with frequency as alpha = 0.56 x f(1.3). As a result, the temperature rise in tofu due to ultrasound absorption is expressed by the product of the acousto/thermal conversion factor and the attenuation/diffraction corrected acoustic intensity. The decrease of temperature rise with depth measured by embedded thermocouples agrees with the theoretical exponential decrease of the attenuation/diffraction corrected acoustic intensity. The heat capacity per unit mass of tofu is 0.76 cal/g degrees C (equivalent to 3.18 J/g degrees C) of which about 76% is water. The nonlinear frequency dependence of attenuation in tofu as f(1.3) correctly describes the frequency dependence of temperature rise. The present results suggest that tofu may only be used in a limited low MHz range in view of the estimation of temperature rise and penetration depth due to nonlinear frequency dependence of attenuation.
authors.affiliation: Division of Physical Metrology, Korea Research Institute of Standards and Science, Yusong, Daejeon, Republic of Korea. ytkim@kriss.re.kr
authors.forename: Yong Tae
authors.initials: YT
authors.lastname: Kim
authors.forename: Ho Chul
authors.initials: HC
authors.lastname: Kim
authors.forename: Matthew
authors.initials: M
authors.lastname: Inada-Kim
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Jung
authors.forename: Yong Hyeon
authors.initials: YH
authors.lastname: Yun
authors.forename: Moon Jae
authors.initials: MJ
authors.lastname: Jho
authors.forename: Kurt
authors.initials: K
authors.lastname: Sandstrom
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods; D008954:Models, Biological; D019047:Phantoms, Imaging; D045730:Soy Foods; D013696:Temperature; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods