A multi-element ultrasonic hyperthermia applicator with independent element control

Underwood, Harold R; Burdette, Everette C.; Ocheltree, K.B.; Magin, Richard L.

doi:10.3109/02656738709140392

Cited by 42 publications

(14 citation statements)

References 9 publications

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“…With the advent of multi-element heating devices, there is increased need for temperature measurements that could provide detailed feedback about temperature distributions. This information in real time would considerably improve the ability to deliver consistently effective temperature distributions [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Non-invasive estimation of hyperthermia temperatures with ultrasound

Arthur

Straube

Trobaugh

et al. 2005

International Journal of Hyperthermia

206

134

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Ultrasound is an attractive modality for temperature monitoring because it is non-ionizing, convenient, inexpensive and has relatively simple signal processing requirements. This modality may be useful for temperature estimation if a temperature-dependent ultrasonic parameter can be identified, measured and calibrated. The most prominent methods for using ultrasound as a non-invasive thermometer exploit either (1) echo shifts due to changes in tissue thermal expansion and speed of sound (SOS), (2) variation in the attenuation coefficient or (3) change in backscattered energy from tissue inhomogeneities. The use of echo shifts has received the most attention in the last decade. By tracking scattering volumes and measuring the time shift of received echoes, investigators have been able to predict the temperature from a region of interest both theoretically and experimentally in phantoms, in isolated tissue regions in vitro and preliminary in vivo studies. A limitation of this method for general temperature monitoring is that prior knowledge of both SOS and thermalexpansion coefficients is necessary. Acoustic attenuation is dependent on temperature, but with significant changes occurring only at temperatures above 50 C, which may lead to its use in thermal ablation therapies. Minimal change in attenuation, however, below this temperature range reduces its attractiveness for use in clinical hyperthermia. Models and measurements of the change in backscattered energy suggest that, over the clinical hyperthermia temperature range, changes in backscattered energy are dependent on the properties of individual scatterers or scattering regions. Calibration of the backscattered energy from different tissue regions is an important goal of this approach. All methods must be able to cope with motion of the image features on which temperature estimates are based. A crucial step in identifying a viable ultrasonic approach to temperature estimation is its performance during in vivo tests.

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Section: Introductionmentioning

confidence: 99%

Non-invasive estimation of hyperthermia temperatures with ultrasound

Arthur

Straube

Trobaugh

et al. 2005

International Journal of Hyperthermia

206

134

View full text Add to dashboard Cite

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“…Multi-element array applicator: Alternatively a heat applicator can be constructed with a fixed spatial array of independently controlled heating elements, such as spiral microstrip [26–28], conformal microwave array (CMA) [30–33], Microtherm 1000 planar array [35] applicators, or a fixed array of ultrasound apertures, such as four and sixteen element devices [60, 61]. …”

Section: Definitions and Characteristic Features Of A Superficial Hypmentioning

confidence: 99%

Quality assurance guidelines for superficial hyperthermia clinical trials

Trefná

Crezee²,

Schmidt

et al. 2017

Strahlenther Onkol

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Quality assurance (QA) guidelines are essential to provide uniform execution of clinical trials with uniform quality hyperthermia treatments. This document outlines the requirements for appropriate QA of all current superficial heating equipment including electromagnetic (radiative and capacitive), ultrasound, and infrared heating techniques. Detailed instructions are provided how to characterize and document the performance of these hyperthermia applicators in order to apply reproducible hyperthermia treatments of uniform high quality. Earlier documents used specific absorption rate (SAR) to define and characterize applicator performance. In these QA guidelines, temperature rise is the leading parameter for characterization of applicator performance. The intention of this approach is that characterization can be achieved with affordable equipment and easy-to-implement procedures. These characteristics are essential to establish for each individual applicator the specific maximum size and depth of tumors that can be heated adequately. The guidelines in this document are supplemented with a second set of guidelines focusing on the clinical application. Both sets of guidelines were developed by the European Society for Hyperthermic Oncology (ESHO) Technical Committee with participation of senior Society of Thermal Medicine (STM) members and members of the Atzelsberg Circle.

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“…The square, multi-element applicator described by Underwood et al (1987) was reported to be heavy and bulky (Samulski et al 1990) and thus would not be suitable for intraoperative use. For the series of patients reported here, we selected a round, planar applicator because of its conformity to the surgical opening and tumour dimensions.…”

Section: Introductionmentioning

confidence: 98%

Techniques for intraoperative hyperthermia with ultrasound: the Dartmouth experience with 19 patients

Ryan

Colacchio²,

Douple

et al. 1992

International Journal of Hyperthermia

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Over the course of 3 years, tumours of 19 patients were heated with ultrasound in the operating room during surgical resection. Immediately following intraoperative radiation therapy, thermocouples were inserted into tumour and adjacent normal structures. Patients were then given a 60-min heat treatment with ultrasound after a 10-15-min heatup period. Temperatures were measured at a total of 133 fixed locations for the 19 patient series. Temperature mapping was done in the tumour volume when logistically feasible. Treatment sites included colorectal (n = 3), portahepatus (n = 1), pancreas (n = 7), liver (n = 1), pelvis (n = 3), sacrum (n = 2), and abdomen (n = 2). A sterile, constant-volume water circulating system was utilized to control surface temperatures. Three generations of completely immersible transducers were designed over the course of this study with a 4-cm height specification. Since the ultrasound transducer was assembled on the sterile field during surgery, a 1, 2 or 3 MHz ceramic element was placed in either a 6, 8 or 10 cm diameter aluminium housing to conform the acoustic field to the tumour size. Average of the maximum temperatures attained was 46.6 degrees C. Temperature with which 90% of all measured points equalled or exceeded (T90) was 39.2 degrees C. The T50 was 42.9 degrees C. This compared favourably with T90 and T50 of 38.8 and 41.9 degrees C, respectively, in our outpatient clinic series, in which superficial tumours were treated with a similar external applicator, and patient tolerance was often a treatment limitation.

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A multi-element ultrasonic hyperthermia applicator with independent element control

Cited by 42 publications

References 9 publications

Non-invasive estimation of hyperthermia temperatures with ultrasound

Non-invasive estimation of hyperthermia temperatures with ultrasound

Quality assurance guidelines for superficial hyperthermia clinical trials

Techniques for intraoperative hyperthermia with ultrasound: the Dartmouth experience with 19 patients

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