Efficient array design for sonotherapy

Stephens, Douglas N.; Kruse, Dustin E.; Ergun, A.S.; Barnes, Stephen; Lu, Xiaofang; Ferrara, Katherine W.

doi:10.1088/0031-9155/53/14/014

Cited by 43 publications

(25 citation statements)

References 23 publications

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“…This issue is naturally exacerbated when the imaging and therapeutic frequencies are quite far from each other. Significant developments based on this approach have nevertheless been reported in the literature, with promising results [23] [24] [25]. Sometimes, USgFUS designers prefer to use so-called "dual-mode transducers", which often means to focus on one of the two modalities at the expense of the other: for instance, [8] primarily designed their USgFUS probe with therapeutic considerations, and methods were later investigated to obtain satisfying images [26].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Gross¹,

Legros

Vince³

et al. 2018

OJAppS

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Capacitive Micromachined Ultrasonic Transducer (CMUT) technology, which has been widely studied in the field of medical imaging, possesses strong design flexibility due to its manufacturing process. Many applications could benefit from this unique feature, especially those that require different operating ultrasonic frequencies. This article reports on the characterization of the therapeutic low-frequency field provided by an ultrasound-guided focused ultrasound CMUT probe that is connected to a custom ultrasonic scanner for hyperthermia applications. The study begins by mapping the focused ultrasonic beam in the vicinity of the focal spot and a parametric analysis providing the maximum peak-to-peak (PTP) pressure delivered by the probe under different acoustic conditions. The measured maximum PTP pressure at the targeted operating frequency of 1 MHz is 3 MPa, with a maximum of 3.6 MPa at 1.25 MHz. Based on an in vitro setup found in the literature, the temperature elevation at the focal point was measured, showing results in agreement with the targeted applications (max. ∆T = 7.5˚C). The article concludes with a reliability study considering the delivered pressure and the self-heating of the CMUT probe: the results show the good stability of the pressure amplitude over 1.8 × 10 9 cycles at a duty cycle of 40%, with a moderate internal heating of 3˚C.

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Section: Introductionmentioning

confidence: 99%

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Gross¹,

Legros

Vince³

et al. 2018

OJAppS

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show abstract

“…Briefly, it consisted of a Siemens Antares ultrasound scanner (Sonoline Antares, Siemens Medical Systems, Inc., Issaquah, WA), a custom dual-mode linear array transducer, and a PC equipped with a temperature control system. The dual-mode linear array transducer has three parallel arrays, including two outer arrays operating at 1.54 MHz for therapeutic application and one center array operating at 5.5 MHz for real-time imaging, as described previously [43, 44]. The two outer arrays are tilted at a 10.2° angle toward the centerline and result in a focal region at 35 mm in depth.…”

Section: Methodsmentioning

confidence: 99%

Dynamic contrast enhanced MRI detects changes in vascular transport rate constants following treatment with thermally-sensitive liposomal doxorubicin

Fite

Kheirolomoom

Foiret

et al. 2017

Journal of Controlled Release

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Temperature-sensitive liposomal formulations of chemotherapeutics, such as doxorubicin, can achieve locally high drug concentrations within a tumor and tumor vasculature while maintaining low systemic toxicity. Further, doxorubicin delivery by temperature-sensitive liposomes can reliably cure local cancer in mouse models. Histological sections of treated tumors have detected red blood cell extravasation within tumors treated with temperature-sensitive doxorubicin and ultrasound hyperthermia. We hypothesize that the local release of drug into the tumor vasculature and resulting high drug concentration can alter vascular transport rate constants along with having direct tumoricidal effects. Dynamic contrast enhanced MRI (DCE-MRI) coupled with a pharmacokinetic model can detect and quantify changes in such vascular transport rate constants. Here, we set out to determine whether changes in rate constants resulting from intravascular drug release were detectable by MRI. We found that the accumulation of gadoteridol was enhanced in tumors treated with temperature-sensitive liposomal doxorubicin and ultrasound hyperthermia. While the initial uptake rate of the small molecule tracer was slower in treated compared to untreated tumors (k1 = 0.0478 ± 0.011 s-1 versus 0.116 ± 0.047 s-1), the tracer was retained after treatment due to a larger reduction in the rate of clearance (k2 = 0.291 ± 0.030 s-1 versus 0.747 ± 0.24 s-1). While DCE-MRI assesses a combination of blood flow and permeability, ultrasound imaging of microvascular flow rate is sensitive only to changes in vascular flow rate; based on this technique, blood flow was not significantly altered 30 minutes after treatment. In summary, DCE-MRI provides a means to detect changes that are associated with treatment by thermally-activated particles and such changes can be exploited to enhance local delivery.

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“…Beams were calculated using the first RayleighSommerfeld solution for a co-linear therapy array geometry, which consists of two parallel therapy arrays of 64 elements each separated by an imaging array (details of the array geometry are presented in [3][4]). Each array was subdivided into 1024 mathematical elements, and the field was calculated in a 2-D plane consisting of 128x128 field points.…”

Section: Beam Calculationsmentioning

confidence: 99%

Function approximations to accelerate 3-D beam predictions for thermal dose calculations

Kruse¹,

Lai²,

Hlawitschka³

et al. 2009

2009 IEEE International Ultrasonics Symposium

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Robust and safe control of tissue heating requires predictions of beam location, temperature and thermal dose in order to optimize the spatial and temporal distribution of acoustic power. Such calculations are computationally intensive, and our objective is to identify methods to speed up such calculations. Monochromatic beam prediction relies heavily on complex exponentials. We have identified a fast 4 th order approximation for the evaluation of a complex exponential using a reduced-complexity polynomial that minimizes absolute error to a maximum of 0.001 over -π to π, and we quantified the effects of the approximation on beam intensity and total acoustic power (TAP) for a 128 physical element transducer array. We demonstrate that ultrasound beam predictions are accelerated by 13x using a fast approximation to evaluate complex exponentials compared to standard libraries.The approximation was optimized to minimize error in TAP, the relevant quantity for thermal diffusion-limited heating. The resulting error in TAP was found to be less than 8x10 -4 %, and the error in intensity was found to be less than 3x10 -2 % as compared to full precision calculations. The same methodology may be applied to other beam prediction algorithms to speed their execution at a relatively minor degradation in accuracy.

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Efficient array design for sonotherapy

Cited by 43 publications

References 23 publications

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Dynamic contrast enhanced MRI detects changes in vascular transport rate constants following treatment with thermally-sensitive liposomal doxorubicin

Function approximations to accelerate 3-D beam predictions for thermal dose calculations

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