Application of a biequational bioheat transfer model in the skin for assessment of thermal characteristics of protective garments Zastosowanie dwurównaniowego modelu transportu ciepła w skórze do oceny charakterystyk cieplnych ubrań ochronnych

2017 ◽  
Vol 1 (2) ◽  
pp. 97-101
Author(s):  
Piotr Łapka
Keyword(s):  
Thermal Characteristics ◽  
Bioheat Transfer ◽  
Transfer Model

Bioheat Transfer in a Branching Countercurrent Network During Hyperthermia

1989 ◽  
Vol 111 (4) ◽  
pp. 263-270 ◽  
Author(s):  
C. K. Charny ◽  
R. L. Levin
Keyword(s):  
Muscle Blood Flow ◽  
Equation Model ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Transfer Model ◽  
Temperature Profiles ◽  
The Mean ◽  
Pennes Model ◽  
Theoretical Results ◽  
Two Parameter

A bioheat transfer model which computes the spatial variations in the arteriole, venule, and muscle temperatures in a human extremity under both resting and hyperthermic conditions is presented. This model uses the two-parameter model first proposed by Baish et al. [2] to account for the heat exchange between tissue and the paired arterioles and venules that comprise the microcirculation. Thermoregulation of the muscle blood flow during hyperthermia is also incorporated into the model. Results show that even when the paired arteriole and venule are assumed to have equal radii, the mean temperature under both steady and transient conditions is not equal to the mean of the arteriole and venule blood temperatures. Tissue temperature profiles during hyperthermia computed with the three-equation model presented in this study are similar in shape and magnitude to those predicted by the traditional one-equation Pennes bioheat transfer model [1]. This is due primarily to the influence of thermoregulatory mechanism in the heated muscle. The unexpected agreement is significant given the inherent relative simplicity of the traditional Pennes model. An “experimental” thermal conductivity is presented to relate the theoretical results to experimental procedures that are widely used to estimate the enhancement of conductivity by perfusion.

Thermal Therapy Protocols for Benign Prostatic Hyperplasia

2007 ◽  
Author(s):  
Daniel Chinn ◽  
Elvis Nditafon ◽  
Alvin Yew ◽  
Chandrasekhar Thamire
Keyword(s):  
Benign Prostatic Hyperplasia ◽  
Thermal Damage ◽  
Prostatic Hyperplasia ◽  
Operating Conditions ◽  
Thermal Therapy ◽  
Bioheat Transfer ◽  
Surrounding Tissue ◽  
Accurate Estimation ◽  
Transfer Model ◽  
Porous Media Model

Thermal therapy for treatment of benign prostatic hyperplasia (BPH) is becoming increasingly popular due to the minimally invasive nature of the treatment. Successful management of such therapy requires accurate estimation of thermal dosage. The purpose of this study is to provide correlations for the thermal damage caused by ultrasound, microwave, and infrared devices under a range of operating conditions. A boundary-fitting finite difference method is used to examine the heat transfer in the prostate gland and surrounding tissue. The Pennes bioheat transfer model and a porous media model were utilized to calculate temperature histories. Necrosis zones were determined using published necrosis data for prostatic tissue and cells. Thermal damage correlations for the three different hyperthermia sources along with sample temperature contours and necrosis zones are presented. Results indicate that the applicator power level and heating time are the most important parameters in achieving the desired necrosis zones, while coolant parameters strongly affect the temperatures of the sensitive urethra and serve as constraints for protocol parameters. Out of the three sources evaluated, ultrasound modality appears to be the most capable of causing necrosis in the target zones, with least damage to the surrounding healthy tissues.

Intensity Based Simulation of the Temperature Prediction in the Focal Region of Liver Using MRI-Guided High Intensity Focused Ultrasound (HIFU)

2016 ◽  
Vol 13 (10) ◽  
pp. 6728-6732
Author(s):  
P Revathy ◽  
V Sadasivam ◽  
T. Ajith Bosco Raj
Keyword(s):  
Focused Ultrasound ◽  
Treatment Time ◽  
Prediction Method ◽  
Treatment Temperature ◽  
High Intensity Focused Ultrasound ◽  
Bioheat Transfer ◽  
Transfer Model ◽  
Focal Region ◽  
Temperature Elevation ◽  
Temperature Prediction

In this research paper a new temperature prediction method is proposed to predict the temperature in liver during thermal ablation which also takes in to account the blood flow cooling. The proposed method suggest a modification of Pennes bioheat transfer equation (PBHTE) inorder to more accurately predict the treatment temperature. The temperature elevation by the proposed heat transfer model is compared with the PBHTE model and the other two heat continuum models by Wulff and Klinger. Appropriate temperature prediction is useful in treatment planning. This may reduce the recurrence level of cancer. Further the reduction in treatment time increases patient safety.

scholarly journals A Generic Bioheat Transfer Thermal Model for a Perfused Tissue

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Devashish Shrivastava ◽  
J. Thomas Vaughan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Rate ◽  
Thermal Model ◽  
Imaging Techniques ◽  
Bioheat Transfer ◽  
Generic Model ◽  
Transfer Model ◽  
Conservation Of Energy ◽  
Simplifying Assumptions

A thermal model was needed to predict temperatures in a perfused tissue, which satisfied the following three criteria. One, the model satisfied conservation of energy. Two, the heat transfer rate from blood vessels to tissue was modeled without following a vessel path. Three, the model applied to any unheated and heated tissue. To meet these criteria, a generic bioheat transfer model (BHTM) was derived here by conserving thermal energy in a heated vascularized finite tissue and by making a few simplifying assumptions. Two linear coupled differential equations were obtained with the following two variables: tissue volume averaged temperature and blood volume averaged temperature. The generic model was compared with the widely employed empirical Pennes’ BHTM. The comparison showed that the Pennes’ perfusion term wCp(1−ε) should be interpreted as a local vasculature dependent heat transfer coefficient term. Suggestions are presented for further adaptations of the general BHTM for specific tissues using imaging techniques and numerical simulations.

Computer Assisted Simulation Model in Cryosurgery for Prostate Tumor

2009 ◽  
Author(s):  
Chih-Wei Chen ◽  
Hong-Sen Kou ◽  
Hsueh-Erh Liu ◽  
Cheng-Keng Chuang ◽  
Li-Jen Wang
Keyword(s):  
Medical Imaging ◽  
Three Dimensional ◽  
Solid Modeling ◽  
Prostate Tumor ◽  
Bioheat Transfer ◽  
Computer Assisted ◽  
Transfer Model ◽  
Prostate Tumors ◽  
Commercial Software ◽  
The Third

Cryosurgery is also called as cryoablation or cryoleision. The third generation of cryo-machine use argon gas for cooling and helium for rewarming to destroy cancer cells. The probes may be put into the tumor during surgery or through the skin (percutaneously). After cryosurgery, the frozen tissue thaws and is either naturally absorbed by the body (for internal tumors), or it dissolves and forms a scab (for external tumors). The main purpose of this paper is to establish a preliminary computer assisted simulation in prostate tumor cryosurgery. A radiologist and an urologist in a medical center in addition to the engineering specialist from the university participated in this interdisciplinary research program. The first step of this simulation protocol is to trim hundreds of two-dimensional medical imaging photos from a patient through the imaging reconstructive software into building a three-dimensional solid modeling. The image data for each patient can be obtained from the x-ray computed tomography (CT), or magnetic resonance imaging (MRI) in the imaging department of hospital. It has successfully built up the related knowledge to overcome the complicacy between the medical imaging modalities and engineering graphic solid modeling with high resolution. It is worthy to mention here that the present solid modeling of prostate can demonstrate the variable diameters and courses of the prostate urethra in vivo. The second step focuses on thermal calculation. So far, there has been no existing commercial software for the specific purpose of the bioheat transfer problem. Hence, user subroutines must be added to the existing commercial software to simulate the clinical situation of cryosurgery. For example, the occurrence of phase change during some specified temperature range and the latent heat of fusion are also incorporated into bio-heat transfer model. It has successfully incorporated bioheat transfer model into the software program to fit the reality in thermal medicine. The third step supplies the data and knowledge concerned with the position of a tumor and the related mechanism of metabolism of living tissue and vessels. The number of probes, the position of each probe, and the operating time of each probe will be explored to ensure a complete killing of the tumor tissue while saving as much healthy surrounding tissue as possible. In this study, the three-dimensional transient temperature distributions based on cryosurgery for prostate tumors have been performed for several cases to find the optimal operating conditions. Different cryoprobes with different freezing time are considered to find the temperature distribution. The simulation results for cryosurgery of prostate tumors will be supplied for practicing physicians as reference to greatly improve the effectiveness of cryosurgery.

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.

Relaxation Time Effect on the Human Head Using the Thermal Wave Model

2012 ◽  
Author(s):  
Toni K. Tullius ◽  
Yildiz Bayazitoglu
Keyword(s):  
Relaxation Time ◽  
Wave Model ◽  
Human Head ◽  
The Body ◽  
Bioheat Transfer ◽  
Time Dependent ◽  
Head Model ◽  
Transfer Model ◽  
The Waves ◽  
The Brain

The most common electronics used by the vast majority of the world’s population emit low radio frequencies and they may be harmful to both skin and brain tissue. The bio-heat transfer model is numerically solved to predict the time dependent temperature distribution of micro waves as it emits to the brain caused by everyday electronics in order to understand the effects the waves have on our organs. A time dependent finite difference technique is used to model a multilayer system depicting this external heat source passing through skin, bone, and into the brain. This model accounts for the extra heat generated within the body from the chemical reactions of the tissue, whereas pervious work took this heat sources to be negligible. A relaxation time is also included in the bioheat transfer model in order to account for the response time the tissue takes caused by the perturbation. Most studies neglect this parameter. Parameters for the adult and child head model are compared. The manuscript is aimed to understand the potential threats on the human body caused by everyday use of the technologies such as Ipods, cellular phones, bluetooth’s, etc.

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