Ultrasonic Power Balances

Davidson, F.

doi:10.1007/978-1-4471-1883-1_6

Cited by 29 publications

(12 citation statements)

References 20 publications

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“…This envelope attenuated the ultrasound pressure by about 9% and was inflated with degassed water to provide acoustic coupling between the transducer and the tissues. Using an acoustic balance technique (28), the electroacoustic efficiency of the applicator was measured as 60% at 10.6 MHz in the absence of the latex balloon. This technique was also used to measure the acoustic intensity at the surface of the transducer as a function of the electric power.…”

Section: Methodsmentioning

confidence: 99%

A renal mass in the setting of a nonrenal malignancy

Sánchez-Ortiz

Madsen

Bermejo

et al. 2004

Cancer

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BACKGROUNDFrequently, a renal mass is identified when patients with cancer undergo studies for staging or surveillance. In determining whether it represents a metastasis, patients are frequently subjected to percutaneous renal biopsies. The authors evaluated their experience with this dilemma to formulate management guidelines.METHODSThe authors reviewed the medical records of 100 consecutive patients with nonrenal malignancies diagnosed with renal masses at presentation or follow‐up. Renal mass histology was available for all patients after nephrectomy or biopsy. Clinical characteristics were assessed to identify factors predictive for a renal metastasis versus a primary renal neoplasm.RESULTSThe only factors predictive of a metastasis to the kidney were progression of the nonrenal malignancy and lack of enhancement of the renal mass (P < 0.0001). Forty‐six patients (46%) had evidence of progression of their nonrenal malignancy in addition to the renal mass. In these patients, the probability of a metastasis to the kidney was 86% (95% confidence interval [CI], 57.2–98.2%) without renal mass enhancement and 32% (95% CI, 14–55%) with enhancing renal masses. None of the 54 patients without signs of progression of their nonrenal malignancy proved to have metastases to the kidney, regardless of the imaging characteristics of the mass (zero probability; 95% CI, 0–7%; P < 0.001).CONCLUSIONSIn patients presenting with renal masses and another clinically localized malignancy, renal mass biopsies were not indicated, as the mass rarely represented a metastasis. These patients may opt for close surveillance or extirpation based on the prognosis of their nonrenal malignancy. Cancer 2004. © 2004 American Cancer Society.

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Section: Methodsmentioning

confidence: 99%

A renal mass in the setting of a nonrenal malignancy

Sánchez-Ortiz

Madsen

Bermejo

et al. 2004

Cancer

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“…To limit energy loss during transmission of the electric signal, a connection with a capacitor-inductor network was included to match the transducer. Using the acoustic balance technique by Davidson 1991 [52], the electroacoustic efficiency of the applicator was measured to 65% at 5.3 MHz. The external face of the transducer was cooled by a continuous flow of degassed water circulating the length of the transducer.…”

Section: Hifu/mri Systemmentioning

confidence: 99%

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

et al. 2012

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link a b s t r a c tThe aim of this study was to evaluate a flat rectangular (3 Â 10 mm 2 ) MRI compatible transducer operating at 5 MHz. The main task was to explore the feasibility of creating deep lesions in heart at a depth of at least 15 mm. The size of thermal necrosis in heart tissue was estimated as a function of power and time using a simulation model. The system was then tested in an excised lamb heart. In this study, we were able to create lesions of 15 mm deep with acoustic power of 6 W for an exposure of approximately 1 min. The contrast to noise ratio (CNR) between lesion and heart tissue was evaluated using fast spin echo (FSE). The CNR value was approximately 22 using T1 W FSE. Maximum CNR was achieved with repetition time (TR) between 300 and 800 ms. Using T2W FSE, the corresponding CNR was approximately 13 for the 14 in vivo experiments. The average lesion depth was 11.93 mm with a standard deviation of 0.62 mm. In vivo irradiation conditions were 6 W for 60 s. The size of the lesion in the other two dimensions was close to 3 Â 10 mm 2 (size of the transducer element).

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“…Fig. 1 Schematic representation of a radiation force balance for determining the output power of a medical ultrasonic transducer [18]. The force on the reflecting target is measured using a balance, where the required sensitivity of the force-measuring instrument deployed is dictated by the magnitude of the force being measured.…”

Section: Measurement Of Acoustic Output Powermentioning

confidence: 99%

Measurements, phantoms, and standardization

Zeqiri

Hodnett

2009

Proc Inst Mech Eng H

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The last 25 years has seen a number of significant developments in the establishment of a measurement infrastructure supporting medical applications of ultrasound. This has allowed manufacturers and users of medical ultrasonic equipment to undertake and compare measurements of key parameters describing the magnitude or strength of the applied ultrasonic field in a meaningful and traceable way: for equipment development, standards compliance, and quality assurance purposes. This paper describes the current state of the art for measurement techniques used to determine the key properties of an ultrasonic field, principally acoustic pressure and acoustic power. Measurement tools and methodologies are described in detail, alongside considerations of how these are likely to develop, shaped by user need. The way that these measurement methods underpin a range of international and national specification standards enabling equipment manufacturers to demonstrate that their equipment is safe and fit for purpose is covered.

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Ultrasonic Power Balances

Cited by 29 publications

References 20 publications

A renal mass in the setting of a nonrenal malignancy

A renal mass in the setting of a nonrenal malignancy

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

Measurements, phantoms, and standardization

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