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Huang W, Ning C, Zhang R, Xu J, Chen B, Li Z, Cui Y, Shao W. Evaluation of the dual-frequency transducer for controlling thermal ablation morphology using frequency shift keying signal. Int J Hyperthermia 2022; 39:1344-1357. [PMID: 36223887 DOI: 10.1080/02656736.2022.2130999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
PURPOSE The catheter-based ultrasound (CBUS) can reach the target tissue directly and achieve rapid treatment. The frequency shift keying (FSK) signal is proposed to regulate and evaluate tumor ablation by a miniaturized dual-frequency transducer. METHODS A dual-frequency transducer prototype (3 × 7 × 0.4 mm) was designed and fabricated for the CBUS applicator (OD: 3.8 mm) based on the fundamental frequency of 5.21 MHz and the third harmonic frequency of 16.88 MHz. Then, the acoustic fields and temperature field distributions using the FSK signals (with 0, 25, 50, 75, and 100% third harmonic frequency duty ratios) were simulated by finite element analysis. Finally, tissue ablation and temperature monitoring were performed in phantom and ex vivo tissue, respectively. RESULTS At the same input electrical power (20 W), the output acoustic power of the fundamental frequency of the transducer was 10.03 W (electroacoustic efficiencies: 50.1%), and that of the third harmonic frequency was 6.19 W (30.6%). As the third harmonic frequency duty ratios increased, the shape of thermal lesions varied from strip to droplet in simulated and phantom experimental results. The same trend was observed in ex vivo tests. CONCLUSION Dual-frequency transducers excited by the FSK signal can control the morphology of lesions. SIGNIFICANCE The acoustic power deposition of CBUS was optimized to achieve precise ablation.
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Affiliation(s)
- Wenchang Huang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Chuanlong Ning
- College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Jiangsu, China
| | - Rui Zhang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Jie Xu
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Beiyi Chen
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Zhangjian Li
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Yaoyao Cui
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Weiwei Shao
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
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Adams MS, Scott SJ, Salgaonkar VA, Jones PD, Plata-Camargo JC, Sommer G, Diederich CJ. Development of an endoluminal high-intensity ultrasound applicator for image-guided thermal therapy of pancreatic tumors. Proc SPIE Int Soc Opt Eng 2015; 9326. [PMID: 26677314 DOI: 10.1117/12.2078841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
An ultrasound applicator for endoluminal thermal therapy of pancreatic tumors has been introduced and evaluated through acoustic/biothermal simulations and ex vivo experimental investigations. Endoluminal therapeutic ultrasound constitutes a minimally invinvasive conformal therapy and is compatible with ultrasound or MR-based image guidance. The applicator would be placed in the stomach or duodenal lumen, and sonication would be performed through the luminal wall into the tumor, with concurrent water cooling of the wall tissue to prevent its thermal injury. A finite-element (FEM) 3D acoustic and biothermal model was implemented for theoretical analysis of the approach. Parametric studies over transducer geometries and frequencies revealed that operating frequencies within 1-3 MHz maximize penetration depth and lesion volume while sparing damage to the luminal wall. Patient-specific FEM models of pancreatic head tumors were generated and used to assess the feasibility of performing endoluminal ultrasound thermal ablation and hyperthermia of pancreatic tumors. Results indicated over 80% of the volume of small tumors (~2 cm diameter) within 35 mm of the duodenum could be safely ablated in under 30 minutes or elevated to hyperthermic temperatures at steady-state. Approximately 60% of a large tumor (~5 cm diameter) model could be safely ablated by considering multiple positions of the applicator along the length of the duodenum to increase coverage. Prototype applicators containing two 3.2 MHz planar transducers were fabricated and evaluated in ex vivo porcine carcass heating experiments under MR temperature imaging (MRTI) guidance. The applicator was positioned in the stomach adjacent to the pancreas, and sonications were performed for 10 min at 5 W/cm2 applied intensity. MRTI indicated over 40°C temperature rise in pancreatic tissue with heating penetration extending 3 cm from the luminal wall.
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Affiliation(s)
- Matthew S Adams
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA 94115 ; Joint Graduate Program in Bioengineering, UC Berkeley and UC San Francisco
| | - Serena J Scott
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA 94115
| | - Vasant A Salgaonkar
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA 94115
| | - Peter D Jones
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA 94115
| | - Juan C Plata-Camargo
- Radiological Sciences Laboratory, Stanford University, 1201 Welch Road, Palo Alto, CA 94304
| | - Graham Sommer
- Stanford Medical Center, 300 Pasteur Drive, Stanford, CA 94305
| | - Chris J Diederich
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA 94115 ; Joint Graduate Program in Bioengineering, UC Berkeley and UC San Francisco
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