Investigation of the Scattering of Focused Ultrasonic Waves at Bones

Author(s):  
Christoph Schaal ◽  
Vibhav Durgesh

High-intensity focused ultrasound (HIFU) can be used for the ablation of tissue, such as in the case of prostate cancer. However, targeting tissue deeper inside the body remains challenging due to the increased attenuation and scattering of the ultrasonic waves. In this work, the partial and complete obstruction of the ultrasonic beam from a HIFU transducer at bones is investigated. Ultrasonic transmission and reflection under such conditions have scarcely been the focus of previous research. Thus, this work provides a reference based on numerical and experimental results. To this end, numerical simulations are conducted for various bone obstruction configurations. In addition, a diffraction-based shadowgraph technique is used for the ultrasound visualization in laboratory experiments. Imaging of focused ultrasonic waves is performed in water with no obstruction, varying partial obstruction, as well as with complete obstruction by bones phantoms. It is shown that there is reasonable agreement between the findings from experiments and simulations. While the field of view in experiments is limited, the entire pressure field in the area of interest can be investigated in numerical simulations. Overall, the results of this work provide a basis for future research in the field of therapeutic ultrasound.

Author(s):  
David Sanford ◽  
Christoph Schaal

Abstract High-intensity focused ultrasound (HIFU) is used clinically to heat cells therapeutically or to destroy them through heat or cavitation. In homogeneous media, the highest wave amplitudes occur at a predictable focal region. However, HIFU is generally not used in the proximity of bones due to wave absorption and scattering. Ultrasound is passed through the skull in some clinical trials, but the complex geometry of the spine poses a greater targeting challenge and currently prohibits therapeutic ultrasound treatments near the vertebral column. This paper presents a comprehensive experimental study involving shadowgraphy and hydrophone measurements to determine the spatial distribution of pressure amplitudes from induced HIFU waves near vertebrae. First, a bone-like composite plate that is partially obstructing the induced waves is shown to break the conical HIFU form into two regions. Wave images are captured using pulsed laser shadowgraphy, and hydrophone measurements over the same region are compared to the shadowgraphy intensity plots to validate the procedure. Next, shadowgraphy is performed for an individual, clean, ex-vivo feline vertebra. The results indicate that shadowgraphy can be used to determine energy deposition patterns and to determine heating at a specific location. The latter is confirmed through additional temperature measurements. Overall, these laboratory experiments may help determine the efficacy of warming specific nerve cells within mammal vertebrae without causing damage to adjacent tissue.


2020 ◽  
Vol 38 (02/03) ◽  
pp. 157-167
Author(s):  
Joseph Chen ◽  
Anne E. Porter ◽  
Kimberly A. Kho

AbstractHistorically, hysterectomy has been the recommended treatment for patients with adenomyosis. However, in the past two decades, various uterine-sparing treatment methods have emerged. These range from excisional techniques such as adenomyomectomy or wedge resection to uterine artery embolization, radiofrequency thermal ablation, hysteroscopic excision, endometrial ablation, and high-intensity focused ultrasound. While largely investigative for the treatment of adenomyosis, these procedures have demonstrated improvement in symptoms including abnormal uterine bleeding, dysmenorrhea, pelvic pain, and overall quality of life. However, long-term data including fertility and obstetric outcomes are needed. Future research is needed to better understand the impact of these uterine-preserving techniques to expand our armamentarium for the treatment of adenomyosis.


2015 ◽  
Vol 33 (7_suppl) ◽  
pp. 133-133 ◽  
Author(s):  
Stephanie Guillaumier ◽  
Neil McCartan ◽  
Louise Dickinson ◽  
Yomi Fatola ◽  
Alex Freeman ◽  
...  

133 Background: There is an increase in the ageing population leading a significant proportion of men diagnosed with prostate cancer being over 75 years of age. Misconceptions regarding treating the elderly are still rife. The body of evidence that has recently emerged shows that this cohort of patients should be offered the same curative therapies as their counterparts. This study looks at the feasibility of focal HIFU in treating localised prostate cancer in those aged over 75 years of age. Methods: Our independent academic HIFU registry incorporates a total of 60 patients who were diagnosed with low, intermediate and high risk localized adenocarcinoma of the prostate, stage T2a-T3aN0M0 and treated with focal HIFU using Sonablate500, between 2004 and 2014. We divided the patient cohort into those that were treated within the remit of a trial protocol, and those that were not. Results: As biochemical failure is difficult to define, we looked at the medium-term transition rates to redo HIFU, local salvage and systemic therapy. 12% required re-treatment with HIFU. 8% transitioned into local salvage or systemic therapy of which 1 patient had radiotherapy and 4 were subsequently treated with androgen deprivation therapy). The table below outlines the complication rates associated with focal HIFU. Conclusions: Focal HIFU has been shown to be both feasible and effective in the elderly population. It is a safe modality of treatment to use in this patient cohort with a low complication profile. Long-term studies are however necessary. [Table: see text]


1998 ◽  
Vol 103 (5) ◽  
pp. 2867-2867 ◽  
Author(s):  
Francesco P. Curra ◽  
Peter Kaczkowski ◽  
Pierre D. Mourad ◽  
Lawrence A. Crum ◽  
Vera A. Khokhlova

Author(s):  
Kohei Okita ◽  
Ryuta Narumi ◽  
Takashi Azuma ◽  
Shu Takagi ◽  
Yoichiro Matsumoto

Therapeutic application of ultrasound is of interest for a tumor treatment, thrombolysis, drag delivery, blood-brain barrier opening and so on. High-intensity focused ultrasound (HIFU) therapy has been developed as the noninvasive treatment deep cancers in particular. Issues as the defocusing and distortion of ultrasound in the body and the long treatment time in current HIFU should be resolved quickly. Numerical simulation is required for the early development of the advance HIFU system.


2012 ◽  
Vol 201-202 ◽  
pp. 521-524
Author(s):  
Li Liu ◽  
Jian Sun

High intensity focused ultrasound (HIFU) is the fourth brand-new and efficient means to cure tumour acknowledged by the medical field. China is one of countries applying HIFU to clinical oncotherapy earliest in the world. However, a considerable part of HIFU equipments which have been put on the market leave unused because accidental injuries such as ambustion to the body surface, tumour tissue residues in the target section or damages to normal tissues are often caused in HIFU clinical treatment. In the thesis, temperature measurement technique of high-intensity focusing ultrasonic therapy is introduced; features and existing problems of two methods (ultrasound and MRI) which are usually used at home and abroad to guide and monitor HIFU treatment are focally analyzed and illustrated.


Author(s):  
Drishti Yadav ◽  
Karan Veer

Background: With the enhancement in manageability and robustness, ultrasound discovers growing usage in an eclectic variety of applications. The capability to accomplish and construe an outsized variability of ultrasound investigations is marvelously revealed by Physicians, nurses and medical officers, and the use of ultrasound in the developing world is unequivocally supported by a growing body of literature. This paper delivers a general idea of the technological and engineering developments that succor in the progression of ultrasonic applications. This paper reviews the prevailing literature in aid of ultrasound use in the emerging biosphere. It also endorses imminent guidelines for ultrasound usage and exploration in order to develop the investigative capability and patient care in the utmost far-flung regions of the world. Methods: A well-thought-out examination of bibliographic records in quest of peer-reviewed research accomplishments by means of an intensive assessment interrogation was carried out. Good quality papers were included in the review based on their features. With the intention of analyzing the verdicts of the considered investigations, we employed an inferential scrutiny approach centered on the quality of the content. Results: A total of 152 papers were included in this review including a massive volume of literature works on various ultrasonic applications. These ultrasonic applications included food processing, cleaning, and nanostructured material synthesis along with a variety of therapeutic and clinical applications. This review identified the captivating improvements and ground-breaking applications of ultrasound worldwide together with a few of its prospective applications. Conclusion: The utilization of ultrasound in processing crafts innovative and attention-grabbing approaches which have an eclectic scope for further research both from industrial and academic perspectives. Various areas, for instance: crystallization, degassing, drying, extraction, filtration, freezing, homogenization, meat tenderization, sterilization, etc.; have been acknowledged with prodigious potential for forthcoming improvements in food processing and preservation. Enriched extraction of heat sensitive bioactive and food constituents at lower processing temperatures can be carried out using UAE. There is also a prospective for attaining concurrent extrication and encapsulation of extracted constituents via ultrasonic. Nevertheless, its utilization in the diagnosis of certain syndromes still remains controversial. In the near future, tumor ablation would necessitate the most important use of high intensity focused ultrasound in medicine. These applications, predominantly the treatment of uterine fibroids, are projected to encounter stretched out usage globally. With the proliferation of additional ablation techniques, a number of electrifying enhancements and innovative applications lie on the vista; together with application for targeted drug delivery and gene therapies, and treatment of an eclectic variety of brain ailments. There is an urgent need to broaden the research to assess the impression of ultrasound in resource-limited settings in the arena of Clinician-performed bedside ultrasonography in an attempt to draw inferences regarding the long-term sustainability and further expansion of ultrasound programs in the developing world. Ultrasonic processing, still in its embryonic stage, entails significant future research with the aim of developing technology and elucidating the effects of ultrasound.


2021 ◽  
Author(s):  
Shahrad Jabbary.

Therapeutic ultrasound is a promising field with many novel applications in medicine and biology. High intensity focused ultrasound (HIFU) provides the ability to localize the deposition of acoustic energy within the body by thermal effect. In this work a brief description of how the HIFU system works and how it can be used to produce localized thermal lesions on the pathogenic tissues in the human body will be presented. Results of acoustic characterization of a hand-held HIFU system developed in our lab will also be presented. The capabilities of creating controlled reversible and irreversible changes in the compound action potential (CAP) values of a specific neural tissue, i.e. lobster abdominal nerves by adjusting different ultrasound parameters (intensity, exposure duration, etc.) in the HIFU system will also be described. Lobster abdominal nerves were exposed to a 10s HIFU exposure. The focal intensity values for this study were chosen as 100, 175, 275, 400, 525 and 700 W .cm ⁻². It was shown that a trend of small changes in the measured CAP values (increase in the CAP amplitude) could be achieved in the five intermediate intensities, while a drastic decrease in the measured CAP values and total degeneration of the nerve could be observed with the highest focal intensity of 700 W .cm⁻².


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