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Title: Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture

Abstract

Prediction and measurement of the acoustic field emitted from a high intensity focused ultrasound (HIFU) is essential for the accurate ultrasonic treatment. In this study, the acoustic field generated from a strongly focused HIFU transmitter was characterized by a combined experiment and simulation method. The spheroidal beam equation (SBE) was utilized to describe the nonlinear sound propagation. The curve of the source pressure amplitude versus voltage excitation was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; finally, the acoustic pressure field generated by the strongly focused HIFU transmitter was predicted by using the SBE model. A commercial fiber optic probe hydrophone was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a large half aperture angle of 30°. The maximum measured peak-to-peak pressure was up to 72 MPa. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results indicate that the current approach might be useful to describe the HIFU field. The results also suggest that this method is not valid for low excitations owing to low sensitivity of the secondmore » harmonic.« less

Authors:
;  [1];  [2];  [3];  [4]; ;  [1];  [1];  [2]
  1. Institute of Acoustics, Key Laboratory of Modern Acoustics, MOE, Nanjing University, Nanjing 210093 (China)
  2. (China)
  3. Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012 (China)
  4. Department of electronic information, Nantong University, Nantong 226019 (China)
Publication Date:
OSTI Identifier:
22271003
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 11; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACOUSTICS; APERTURES; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DIAGRAMS; DIFFERENTIAL EQUATIONS; ELECTRIC POTENTIAL; EXCITATION; NONLINEAR PROBLEMS; OPTICAL FIBERS; ULTRASONIC WAVES

Citation Formats

Chen, Tao, Fan, Tingbo, Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012, Zhang, Wei, Qiu, Yuanyuan, Tu, Juan, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, Guo, Xiasheng, Zhang, Dong, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, and Institute of Acoustics, State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190. Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture. United States: N. p., 2014. Web. doi:10.1063/1.4868597.
Chen, Tao, Fan, Tingbo, Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012, Zhang, Wei, Qiu, Yuanyuan, Tu, Juan, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, Guo, Xiasheng, Zhang, Dong, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, & Institute of Acoustics, State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190. Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture. United States. doi:10.1063/1.4868597.
Chen, Tao, Fan, Tingbo, Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012, Zhang, Wei, Qiu, Yuanyuan, Tu, Juan, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, Guo, Xiasheng, Zhang, Dong, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn, and Institute of Acoustics, State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190. Fri . "Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture". United States. doi:10.1063/1.4868597.
@article{osti_22271003,
title = {Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture},
author = {Chen, Tao and Fan, Tingbo and Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012 and Zhang, Wei and Qiu, Yuanyuan and Tu, Juan, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn and Guo, Xiasheng and Zhang, Dong, E-mail: juantu@nju.edu.cn, E-mail: dzhang@nju.edu.cn and Institute of Acoustics, State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190},
abstractNote = {Prediction and measurement of the acoustic field emitted from a high intensity focused ultrasound (HIFU) is essential for the accurate ultrasonic treatment. In this study, the acoustic field generated from a strongly focused HIFU transmitter was characterized by a combined experiment and simulation method. The spheroidal beam equation (SBE) was utilized to describe the nonlinear sound propagation. The curve of the source pressure amplitude versus voltage excitation was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; finally, the acoustic pressure field generated by the strongly focused HIFU transmitter was predicted by using the SBE model. A commercial fiber optic probe hydrophone was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a large half aperture angle of 30°. The maximum measured peak-to-peak pressure was up to 72 MPa. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results indicate that the current approach might be useful to describe the HIFU field. The results also suggest that this method is not valid for low excitations owing to low sensitivity of the second harmonic.},
doi = {10.1063/1.4868597},
journal = {Journal of Applied Physics},
number = 11,
volume = 115,
place = {United States},
year = {Fri Mar 21 00:00:00 EDT 2014},
month = {Fri Mar 21 00:00:00 EDT 2014}
}
  • The possibility of using the opto-acoustic (OA) method for monitoring high-intensity ultrasonic therapy is studied. The optical properties of raw and boiled liver samples used as the undamaged model tissue and tissue destroyed by ultrasound, respectively, are measured. Experiments are performed with samples consisting of several alternating layers of raw and boiled liver of different thickness. The position and transverse size of the thermal lesion were determined from the temporal shape of the OA signals. The results of measurements are compared with the real size and position of the thermal lesion determined from the subsequent cuts of the sample. Itmore » is shown that the OA method permits the diagnostics of variations in biological tissues upon ultrasonic therapy. (special issue devoted to multiple radiation scattering in random media)« less
  • No abstract prepared.
  • This study was to evaluate the effect of pre-exposure lower-intensity focused ultrasound(US), or LIFU, in high-intensity focused ultrasound(HIFU) ablation of rabbit VX2 liver tumors . Liver VX2 tumor models were established in 30 rabbits, which were divided randomly into two groups. The liver tumors of rabbits in Group A underwent single HIFU ablation; those in Group B were given LIFU exposure before HIFU treatment. Five rabbits from each of the two groups were sacrificed at 0 hours, 3 days, and 7 days after HIFU ablation. Tissue samples that included targeted and short-range sounding (s-RS, within 5 mm of the targeted)more » and far-range sounding (f-RS, more than 5 mm of the targeted) tissues were observed using light microscope and transmission electron microscopy. The histological examination indicated that not only the targeted tumor cells became irreversible damage, but also the short-range sounding tumors were severely damaged by the HIFU with LIFU pre-exposure in group B. It is concluded that LIFU pre-exposure can enhance the effects of HIFU ablation on the destruction of cell ultrastructures and can enlarge the region of HIFU ablation.« less
  • Purpose: Interstitial high intensity therapeutic ultrasound (HITU) applicators can be used to ablate tissue percutaneously, allowing for minimally-invasive treatment without ionizing radiation [1,2]. The purpose of this study was to evaluate the feasibility and usability of combining multielement interstitial HITU applicators with a clinical magnetic resonance imaging (MRI)-guided focused ultrasound software platform. Methods: The Sonalleve software platform (Philips Healthcare, Vantaa, Finland) combines anatomical MRI for target selection and multi-planar MRI thermometry to provide real-time temperature information. The MRI-compatible interstitial US applicators (Acoustic MedSystems, Savoy, IL, USA) had 1–4 cylindrical US elements, each 1 cm long with either 180° or 360°more » of active surface. Each applicator (4 Fr diameter, enclosed within a 13 Fr flexible catheter) was inserted into a tissue-mimicking agar-silica phantom. Degassed water was circulated around the transducers for cooling and coupling. Based on the location of the applicator, a virtual transducer overlay was added to the software to assist targeting and to allow automatic thermometry slice placement. The phantom was sonicated at 7 MHz for 5 minutes with 6–8 W of acoustic power for each element. MR thermometry data were collected during and after sonication. Results: Preliminary testing indicated that the applicator location could be identified in the planning images and the transducer locations predicted within 1 mm accuracy using the overlay. Ablation zones (thermal dose ≥ 240 CEM43) for 2 active, adjacent US elements ranged from 18 mm × 24 mm (width × length) to 25 mm × 25 mm for the 6 W and 8 W sonications, respectively. Conclusion: The combination of interstitial HITU applicators and this software platform holds promise for novel approaches in minimally-invasive MRI-guided therapy, especially when bony structures or air-filled cavities may preclude extracorporeal HIFU.[1] Diederich et al. IEEE UFFFC 46.5 (1999): 1218.[2] Chopra et al. PMB 50.21 (2005): 4957. Funding support was provided by Philips Healthcare and in-kind support from Acoustic MedSystems Inc. Ari Partanen is a paid employee of Philips Healthcare. Goutam Ghoshal and Everette Clif Burdette are paid employees of Acoustic MedSystems Inc.« less
  • To demonstrate the feasibility of CT and B-mode Ultrasound (US) targeted HIFU, a prototype coaxial focused ultrasound transducer was registered and integrated to a CT scanner. CT and diagnostic ultrasound were used for HIFU targeting and monitoring, with the goals of both thermal ablation and non-thermal enhanced drug delivery. A 1 megahertz coaxial ultrasound transducer was custom fabricated and attached to a passive position-sensing arm and an active six degree-of-freedom robotic arm via a CT stereotactic frame. The outer therapeutic transducer with a 10 cm fixed focal zone was coaxially mounted to an inner diagnostic US transducer (2-4 megahertz, Philipsmore » Medical Systems). This coaxial US transducer was connected to a modified commercial focused ultrasound generator (Focus Surgery, Indianapolis, IN) with a maximum total acoustic power of 100 watts. This pre-clinical paradigm was tested for ability to heat tissue in phantoms with monitoring and navigation from CT and live US. The feasibility of navigation via image fusion of CT with other modalities such as PET and MRI was demonstrated. Heated water phantoms were tested for correlation between CT numbers and temperature (for ablation monitoring). The prototype transducer and integrated CT/US imaging system enabled simultaneous multimodality imaging and therapy. Pre-clinical phantom models validated the treatment paradigm and demonstrated integrated multimodality guidance and treatment monitoring. Temperature changes during phantom cooling corresponded to CT number changes. Contrast enhanced or non-enhanced CT numbers may potentially be used to monitor thermal ablation with HIFU. Integrated CT, diagnostic US, and therapeutic focused ultrasound bridges a gap between diagnosis and therapy. Preliminary results show that the multimodality system may represent a relatively inexpensive, accessible, and simple method of both targeting and monitoring HIFU effects. Small animal pre-clinical models may be translated to large animals and humans for HIFU-induced ablation and drug delivery. Integrated CT-guided focused ultrasound holds promise for tissue ablation, enhancing local drug delivery, and CT thermometry for monitoring ablation in near real-time.« less