title: Photo-acoustic excitation and optical detection of fundamental flexural guided wave in coated bone phantoms.
abstract: Photo-acoustic (PA) imaging was combined with skeletal quantitative ultrasound (QUS) for assessment of human long bones. This approach permitted low-frequency excitation and detection of ultrasound so as to efficiently receive the thickness-sensitive fundamental flexural guided wave (FFGW) through a coating of soft tissue. The method was tested on seven axisymmetric bone phantoms, whose 1- to 5-mm wall thickness and 16-mm diameter mimicked those of the human radius. Phantoms were made of a composite material and coated with a 2.5- to 7.5-mm layer of soft material that mimicked soft tissue. Ultrasound was excited with a pulsed Nd:YAG laser at 1064-nm wavelength and received on the same side of the coated phantom with a heterodyne interferometer. The FFGW was detected at 30-kHz frequency. Fitting the FFGW phase velocity by the FLC(1,1) tube mode provided an accurate (9.5 ± 4.0%) wall thickness estimate. Ultrasonic in vivo characterization of cortical bone thickness may thus become possible.
authors.affiliation: Department of Physics, University of Jyväskylä, Jyväskylä, Finland. Electronic address: petro.moilanen@jyu.fi.
authors.forename: Petro
authors.initials: P
authors.lastname: Moilanen
authors.affiliation: Department of Physics, University of Jyväskylä, Jyväskylä, Finland; Department of Electrical Engineering, University of Oulu, Oulu, Finland.
authors.forename: Zuomin
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Department of Physics, University of Helsinki, Helsinki, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Karppinen
authors.affiliation: Department of Physics, University of Helsinki, Helsinki, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Karppinen
authors.affiliation: Department of Physics, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Vantte
authors.initials: V
authors.lastname: Kilappa
authors.affiliation: Department of Physics, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Jalmari
authors.initials: J
authors.lastname: Pirhonen
authors.affiliation: Department of Electrical Engineering, University of Oulu, Oulu, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Myllylä
authors.affiliation: Department of Physics, University of Helsinki, Helsinki, Finland.
authors.forename: Edward
authors.initials: E
authors.lastname: Haeggström
authors.affiliation: Department of Physics, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Timonen
mesh_terms: D000161:Acoustic Stimulation / Q000295:instrumentation; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000502:physiology* / Q000528:radiation effects; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis*; D003720:Densitometry / Q000295:instrumentation* / Q000379:methods; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007834:Lasers; D019047:Phantoms, Imaging; D010775:Photic Stimulation / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013016:Sound
chemical_list: D020099:Coated Materials, Biocompatible
keywords: Axial transmission; Cortical bone; Guided waves; Osteoporosis; Photo-acoustics; Quantitative ultrasound