title: Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies.
abstract: This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm(-2). By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.
authors.affiliation: INSERM, Unité 556, 151 Cours Albert Thomas, 69424 Lyon, France. melodelima@lyon.inserm.fr
authors.forename: David
authors.initials: D
authors.lastname: Melodelima
authors.forename: Cyril
authors.initials: C
authors.lastname: Lafon
authors.forename: Frederic
authors.initials: F
authors.lastname: Prat
authors.forename: Alain
authors.initials: A
authors.lastname: Birer
authors.forename: Dominique
authors.initials: D
authors.lastname: Cathignol
mesh_terms: D004938:Esophageal Neoplasms / Q000628:therapy*; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D009336:Necrosis; D014464:Ultrasonic Therapy / Q000379:methods; D014465:Ultrasonics; D014867:Water
chemical_list: D014867:Water