Blood perfusion and thermal conduction effects in Gaussian beam, minimum time single-pulse thermal therapies

2005 ◽  
Vol 32 (2) ◽  
pp. 311-317 ◽  
Author(s):  
Kung-Shan Cheng ◽  
Robert B. Roemer
Keyword(s):  
Gaussian Beam ◽  
Thermal Conduction ◽  
Blood Perfusion ◽  
Single Pulse ◽  
Minimum Time ◽  
Thermal Therapies

Cooling Limit Approach for Single-Pulse Thermal Therapies

2004 ◽  
Author(s):  
Kung-Shan Cheng
Keyword(s):  
Closed Form ◽  
Upper Bound ◽  
Treatment Protocol ◽  
Blood Perfusion ◽  
Single Pulse ◽  
Peak Temperature ◽  
Thermal Dose ◽  
Efficient Treatment ◽  
Period 2 ◽  
Thermal Therapies

Based upon the commonly used Sapareto-Dewey thermal dose formula, a thermal treatment is divided into four periods: 1) period-1 is from 37°C to 43°C, 2) period-2 is from 43°C to Tpeak, 3) period-3 is from Tpeak to 43°C, and 4) period-4 is 43°C to 38°C. A recent study derived a closed form thermal dose formula based on a combined term, the “effective cooling frequency,” revealed that one can determine the best performance of a thermal therapy by concentrating on the cooling periods: period-3 and period-4. As an extension, this study used a closed-form temperature solution to investigate the influences from both cooling terms (perfusion and thermal conduction) separately. The results determined the upper bound of the peak temperature for pulses with different focal sizes under different blood perfusion values. Under practical settings, no pulse should introduce peak temperature higher than 67°C to avoid overdosing when the desired thermal dose is 240CEM43°C. It also showed that pulses with focal size smaller than or equal to 4 mm benefit the perfusion independence for the following quantities: the upper bound on the peak temperature, the treatment size, and the time/temperature for which 90% thermal dose is accumulated. Thus the conduction dominates the cooling process for each single pulse heated by the highly focused SFUS applicators when the pulses are properly isolated temporally. Results from this study further provide an estimation of the closest distance between two pulses and the time/temperature to re-activate the consecutive pulses. Thus the results can guide the researchers to design more efficient treatment protocol for multiple-pulse thermal therapies.

MR thermometry-based feedback control of efficacy and safety in minimum-time thermal therapies: Phantom andin-vivoevaluations

2006 ◽  
Vol 22 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Dhiraj Arora ◽  
Daniel Cooley ◽  
Trent Perry ◽  
Junyu Guo ◽  
Andrew Richardson ◽  
...  
Keyword(s):  
Feedback Control ◽  
Minimum Time ◽  
Efficacy And Safety ◽  
Mr Thermometry ◽  
Thermal Therapies

The Thermoinduced Self-Action of the Gaussian Beam of Radiation in the Dispersion Liquid Medium

2010 ◽  
Vol 5 (1) ◽  
pp. 5-8
Author(s):  
Valeriy I. Ivanov ◽  
Albert I. Livashvili
Keyword(s):  
Liquid Medium ◽  
Gaussian Beam ◽  
Light Beam ◽  
Thermal Diffusion ◽  
Analytical Solutions ◽  
Thermal Conduction ◽  
Light Field ◽  
Focal Distance ◽  
Fluid Medium ◽  
Diffusion Flows

The change of the concentration of nanoparticles in the fluid medium which is under the influence of a Gaussian light beam is theoretically explored. Analytical solutions of the nonsteady equations of a thermal conduction and transport of particles taking into account thermal diffusion flows are gained. The expression for a focal distance of the thermoinduced lens resulting self-action of a light field is found.

scholarly journals Minimum-Time Thermal Dose Control of Thermal Therapies

2005 ◽  
Vol 52 (2) ◽  
pp. 191-200 ◽  
Author(s):  
D. Arora ◽  
M. Skliar ◽  
R.B. Roemer
Keyword(s):  
Minimum Time ◽  
Thermal Dose ◽  
Thermal Therapies ◽  
Dose Control

Constrained Predictive Control of Thermal Therapies for Minimum-Time Delivery of Thermal Dose

2007 ◽  
Vol 15 (6) ◽  
pp. 1030-1037 ◽  
Author(s):  
Dhiraj Arora ◽  
Mikhail Skliar ◽  
Daniel Cooley ◽  
Robert B. Roemer
Keyword(s):  
Predictive Control ◽  
Minimum Time ◽  
Thermal Dose ◽  
Thermal Therapies

Generation and Dissipation of Heat in Vocal Fold Tissue

1985 ◽  
Vol 28 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Donald S. Cooper ◽  
Ingo R. Titze
Keyword(s):  
Temperature Rise ◽  
Thermal Conduction ◽  
Vocal Fold ◽  
Time Course ◽  
Blood Perfusion ◽  
Vocal Folds ◽  
Ambient Air ◽  
Future Studies ◽  
Fine Wire ◽  
Viscous Loss

The power dissipated in the vocal folds during phonation results from viscous loss in the fold tissues and can be estimated on the basis of a simplified representation of the geometry and movement of the folds. Assuming this power is converted into heat, it combines with the effects of muscle contraction, blood perfusion, and thermal conduction to the surface of the folds to determine fold temperature. To isolate the thermomechanical source of heat, the vocal folds of excised larynges were vibrated vertically over a range of frequencies and amplitudes, while the temperature rise in them was measured by inserted fine-wire thermocouples. The temperature rise observed was somewhat smaller than that predicted. This may be partly accounted for by convective and evaporative cooling of the vocal fold as it moved relative to the ambient air. Future studies should consider the time course of heating and vocal fold geometry in more detail.

Cryosurgery as an Alternative Treatment for Menorrhagia and Uterine Fibroids

2010 ◽  
Author(s):  
Katherine L. McCaffrey ◽  
Karen M. Rose ◽  
John P. Abraham
Keyword(s):  
Cooling Rate ◽  
Solid Phase ◽  
Treatment Options ◽  
Uterine Fibroids ◽  
Blood Perfusion ◽  
Uterine Wall ◽  
Bioheat Transfer ◽  
Transfer Model ◽  
Thermal Therapies ◽  
Survival Studies

Nearly 80% of all women may suffer from uterine fibroids (leiomyomas) and/or menorrhagia, which is a condition where the uterus walls bleed abnormally. The vast majority of women whose symptoms are strong enough to require treatment obtain a hysterectomy. Other treatment options which are less invasive than hysterectomy include thermal therapies such as thermal ablation or cryosurgical removal of tissue. This project numerically evaluates the efficacy of a liquid-nitrogen-based cryotherapy for the treatment of uterine fibroids. A bioheat transfer model was utilized which included both the effects of blood perfusion and the impacts of liquid-to-solid phase change. An upper limit on the cooling rate was obtained by simulating a direct contact between the probe tip and the inner lining of the uterus. Calculations were carried out for a one-minute treatment duration with 720 calculation nodes which spanned the thickness of the uterine wall. Results obtained from the calculations allowed a determination of the cooling rate at each nodal location within the tissue. Based on data obtained from previous cell-survival studies, it was found that necrosis would occur within the tissue up to a depth of approximately 5.8 mm.

Optimal Power Deposition Patterns for Single Pulse High Temperature Therapies With Temperature-Dependent Perfusion

2004 ◽  
Author(s):  
Kung-Shan Cheng
Keyword(s):  
High Temperature ◽  
Normal Tissue ◽  
Blood Perfusion ◽  
Single Pulse ◽  
Thermal Treatments ◽  
Temperature Dependent ◽  
Power Deposition ◽  
Deposition Patterns ◽  
Optimal Power ◽  
Short Time

The blood perfusion has been know to be an important factor of a thermal therapy, furthermore there were experiments shown that both normal tissue and tumor have different temperature-dependent perfusions. Since it has been shown by a recent study that the optimal power deposition patterns producing uniform tumor thermal dose distributions exist for thermal treatments ranging from the conventional hyperthermia to the high temperature therapy, this motivates performing a study on the optimal power deposition patterns for the high temperature therapy. This study showed that there are such optimal power deposition patterns for different tumor sizes by applying a 5-sec heating pulse with different out-tumor heat patterns even when the tumor and normal tissue both have different temperature-dependent perfusions. With this short heating, the optimal power patterns for temperature dependent perfusion models are almost identical to the corresponding constant perfusion models. In addition to this perfusion-independence, when tumor size is at least 4cm, even the treatment times from both perfusion models are almost the same. Furthermore, the simulations also showed that the optimal power deposition patterns are not sensitive to the out-tumor heating patterns, provided the heating applicator is not poorly focused. Results of the study motivate the thermal treatment community to perform more studies on the short-time high-temperature therapy to benefit these blood perfusion independences.

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