Ultrasound Computed Tomography of children long bones using a dual-frequency transducer array
Résumé
B-mode ultrasound (echography) has long been a first-line examination for the diagnosis of many diseases in children. The other modalities, such as X-ray or magnetic resonance imaging, are often associated with inconveniences of variable importance (cost, irradiation, sedation, accessibility) that are constraining for pediatric applications [1]. But B-mode ultrasound has difficulty penetrating bone and the locks associated with the in-vivo configuration are still numerous: image resolution and the contrast in the deep zone; accessibility of anatomical sites, or in between the two leg and arm bones. Ultrasonic Computed Tomography (USCT) is a relevant modality to bone tissues imaging [2], [3]. The acquisition geometry of the signals is no longer linear nor sectoral, as in B-mode ultrasound, but circular in the orthogonal plane, and based on a multiplexed dual-frequency 2D-ring antenna allowing electronical and mechanical scanning. The antenna supports 8 fixed transducers distributed over 360�. The Mistras-Eurosonic? multiplexer is equipped with an 8-by-8 parallel-channel acquisition system. The 8 transducers are Imasonic? piezo-composite transducers with a center frequency of 1MHz and 2.25MHz. Each transducer is 60 mm high and 56 mm in diameter. These transducers have cylindrical focusing with a focal length of 150 mm, a lateral aperture size of 40 mm and an axial aperture size of 30 mm. The slice thickness is 3 mm. Results obtained on rectified non-circular cylindrical tubes, on paired bones (Sawbones�) are presented. References [1] P. Petit et al., ?Am. J. Roentgenol., vol. 176, no. 4, pp. 987?990, Apr. 2001. [2] P. Lasaygues et al., Proceedings of the Int. Workshop on MUST, Speyer, Germany, 2017. [3] S. Bernard, et al., Phys. Med. Biol., vol. 62, no. 17, pp. 7011?7035, Aug. 2017. Acknowledgements This research was supported by the Provence-Alpes-Côte d'Azur ? PACA Regional Council, under Grant No.2016₀2696.