Lithium niobate transducers for MRI-guided ultrasonic microsurgery
Résumé
Focused ultrasound surgery (FUS) is usually based on frequencies below 5 MHz, typically around 1 MHz. Whilst this allows good penetration into tissue, it limits the minimum lesion dimensions that can be achieved. In the study reported here, we investigate devices to allow FUS at much higher frequencies, therefore in principle reducing the minimum lesion dimensions. Furthermore, FUS can produce deep-sub-millimetre demarcation between viable and necrosed tissue; high frequency devices may allow this to be exploited in superficial applications which may include dermatology, ophthalmology, treatment of the vascular system, and treatment of early dysplasia in epithelial tissue. In this paper we explain the methodology we have used to build high-frequency high-intensity transducers using Y-36 • cut lithium niobate. This material was chosen as its low losses give it the potential to allow very high-frequency operation at harmonics of the fundamental operating frequency. A range of single element transducers with a centre frequency between 6.6 MHz and 20.0 MHz were built and the transducers' efficiency and acoustic power output were measured. A focused 6.6-MHz transducer was built with multiple elements operating together and tested using an ultrasound phantom and MRI scans. It was shown to increase phantom temperature by 32 • C in a localised area of 2.5 mm × 3.4 mm in the plane of the MRI scan. Tests on poultry were also performed and shown to create lesions of similar dimensions. This study therefore demonstrates that it is feasible to produce high-frequency transducers capable of high-resolution FUS using lithium niobate.
Domaines
Acoustique [physics.class-ph]
Fichier principal
Revised Document_Lithium niobate transducers for MRI-guided ultrasonic microsurgery.pdf (352.71 Ko)
Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)