Biological effects of ultrasound

Carstensen, Edwin L.; Miller, Morton W.; Linke, Charles A.

doi:10.1007/bf02308984

Cited by 74 publications

(16 citation statements)

References 16 publications

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“…In drug testing, dose is usually expressed in terms of so many units of drug per kilogram of tissue (e.g., 6 lg/ kg of body weight). In thermal biology, a useful concept of dose can be derived from an Arrhenius equation (Carstensen et al, 1974), which posits that effects are linearly related to the duration of the temperature increase and exponentially related to the temperature elevation. Sapareto and Dewey (1984) and Dewey (1994) subsequently applied this equation to their efforts in deriving effective thermal doses for obtaining therapeutic mitigation of certain forms of cancerous conditions.…”

Section: Determination Of a Thermal Dose And Its Isodosesmentioning

confidence: 99%

Fetal thermal dose considerations during the obstetrician's watch: Implications for the pediatrician's observations

Miller

Church

Miller

et al. 2007

Birth Defects Research Pt C

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There are a number of seemingly "usual" thermal episodes during pregnancy for which it is relatively easy to determine a rudimentary aspect of thermal dose; these episodes include fever, labor, labor plus epidural, and the normally-occurring 0.5 degrees C temperature elevation above maternal core temperature of the fetus during the entirety of the third trimester. Complications can involve, for instance, fever during the third trimester. We consider the thermal doses of five different but "usual" or "normal" hyperthermic episodes during human pregnancy and compare those doses with the thermal doses involved with both single and cohort exposures of pregnant guinea pigs throughout their gestational period. The end-point studied in the guinea pigs was microencephaly. In nine of the 10 comparisons (human fetal thermal dose vs. guinea pig fetal thermal dose) the human dose is substantially larger than that of the guinea pig thermal dose, which was substantially teratogenic. This situation is essentially the inverse of the type of information contained in the Physician's Desk Reference (PDR) on drugs, in which it is not unusual to discern that at high drug levels there may be teratogenic effects in laboratory animals, but such effects were not observed at "clinical" drug levels in animals or subsequent clinical trials. With hyperthermic events, however, it appears that the teratogenically-effective thermal dose levels associated with animal testing are quite low relative to those thermal doses associated with relatively "normal" obstetric observations during a pregnancy.

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Section: Determination Of a Thermal Dose And Its Isodosesmentioning

confidence: 99%

Fetal thermal dose considerations during the obstetrician's watch: Implications for the pediatrician's observations

Miller

Church

Miller

et al. 2007

Birth Defects Research Pt C

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“…This integral has been postulated as a useful index of thermally induced tissue alterations. It is based upon an empirical observation that the temperature elevations and corresponding exposure times needed for cellular effects are related to each other by the same relationships that govern chemical reaction kinetics [13,15]. In order to determine whether a reaction goes to completion, the damage integral evaluates the comulative thermal time-history and relates it to an activation energy that is specific to the tissue being studied.…”

Section: T(xt) = K V2 T (Xt)-t(xt) I R+ H (Xt)mentioning

confidence: 99%

“…Tissue alteration occurs if the value of the integral exceeds a threshold level. Specifically, the damage integral [13] is defined as…”

Section: T(xt) = K V2 T (Xt)-t(xt) I R+ H (Xt)mentioning

confidence: 99%

A Theoretical Thermal Model of Ultrasonic Hyperthermia

Shriwastava

Singh

1994

IETE Journal of Research

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“…These observations can be explained quantitatively by a model which is based on the conversion of ultrasonic energy to heat by absorption and the diffusion of heat from the sound beam (Pond, 1970;Carstensen et al, 1974). The thermal damage itself can be treated adequately as a chemical rate process with a single activation energy (Henriques, 1947).…”

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confidence: 99%

Finite amplitude effects on the thresholds for lesion production in tissues by unfocused ultrasound

Carstensen

Becroft

Law

et al. 1981

The Journal of the Acoustical Society of America

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The phenomenon of thermal lesion production in tissues by unfocused ultrasound has been modeled under the assumptions (1) that damage to the tissues is the result of a chemical rate process and (2) that the time-temperature exposure of the tissue results from a competition between the rate of heat generation by absorption of ultrasonic energy and thermal diffusion. The model was tested by observing thresholds for color change in samples of excised bovine liver at 6 cm from a 2.25-MHz, 1.27-cm-diam piston source and 11.5 cm from a 4.4-MHz, 1.27-cm source. The observations disagreed sharply with predictions of the linear model. However, after recognition of the fact that finite amplitude phenomena modify the effective absorption coefficients of the tissues, the model gives excellent predictions of observed thresholds simply by using intensity dependent values of the absorption coefficients in the numerical calculations. Thermoelectric and radiation force methods were used to demonstrate the noblinear absorption phenomenon in excised liver. In contrast with the case of focused ultrasound, the thresholds for lesion formation by unfocused sources (1) occur at lower intensities, (2) are strongly dependent upon frequency, and (3) because acoustic saturation in the coupling medium imposes lower limits on tissue intensities for unfocused than for focused ultrasound, unfocused lesions are limited to relatively long exposure times.

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Biological effects of ultrasound

Cited by 74 publications

References 16 publications

Fetal thermal dose considerations during the obstetrician's watch: Implications for the pediatrician's observations

Fetal thermal dose considerations during the obstetrician's watch: Implications for the pediatrician's observations

A Theoretical Thermal Model of Ultrasonic Hyperthermia

Finite amplitude effects on the thresholds for lesion production in tissues by unfocused ultrasound

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