Experimental Validation of an Inverse Heat Transfer Algorithm for Optimizing Hyperthermia Treatments

2006 ◽  
Vol 128 (4) ◽  
pp. 505-515 ◽  
Author(s):  
F. Scott Gayzik ◽  
Elaine P. Scott ◽  
Tahar Loulou
Keyword(s):  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Treatment Protocol ◽  
Bioheat Transfer ◽  
Transient Temperature ◽  
Transfer Model ◽  
Minimization Algorithm ◽  
Hyperthermia Treatment ◽  
Extent Of Damage

Hyperthermia is a cancer treatment modality in which body tissue is exposed to elevated temperatures to destroy cancerous cells. Hyperthermia treatment planning refers to the use of computational models to optimize the heating protocol with the goal of isolating thermal damage to predetermined treatment areas. This paper presents an algorithm to optimize a hyperthermia treatment protocol using the conjugate gradient method with the adjoint problem. The output of the minimization algorithm is a heating protocol that will cause a desired amount of thermal damage. The transient temperature distribution in a cylindrical region is simulated using the bioheat transfer equation. Temperature and time are integrated to calculate the extent of thermal damage in the region via a first-order rate process based on the Arrhenius equation. Several validation experiments are carried out by applying the results of the minimization algorithm to an albumen tissue phantom. Comparisons of metrics describing the damage region (the height and radius of the volume of thermally ablated phantom) show good agreement between the desired extent of damage and the measured extent of damage. The sensitivity of the bioheat transfer model and the Arrhenius damage model to their constituent parameters is calculated to create a tolerable range of error between the desired and measured extent of damage. The measured height and radius of the ablated region fit well within the tolerable range of error found in the sensitivity analysis.

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.

Temperature Profiles in a Finite Element Thermal Model of the Prostate Region Under Hyperthermia Treatment

1990 ◽  
Vol 189 ◽  
Author(s):  
Indira Chatterjee ◽  
Roy E. Adams ◽  
Namdar Saniei
Keyword(s):  
Finite Element ◽  
Phased Array ◽  
Blood Perfusion ◽  
Element Model ◽  
Bioheat Transfer ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Hyperthermia Treatment ◽  
Finite Element Software ◽  
Transient Temperature Distribution

ABSTRACTThe detailed transient temperature distribution in an inhomogeneous model of a cross section through the prostate region of the human body undergoing hyperthermia treatment forcancer has been calculated. The finite element method has been used to solve the bioheattransfer equation. A commercially available finite element software package called ANSYS® has been adapted to the present problem.The model consists of 523 triangular elements and incorporates a tumor in the prostate.The hyperthermia device under test is an Annular Phased Array consisting of dipole antennas. The model is surrounded by a bolus of deionized water. The calculated electromagnetic energy distribution is input into the bioheat transfer equation and the resulting temperature distributions calculated.The increase in blood perfusion rates due to heating is incorporated into the model. Detailed transient temperature profiles in the finite element model are presented for various values of blood perfusion rates in the tumor and surrounding tissues. It is observed that the Annular Phased Array is effective in raising the temperature of the tumor to therapeutic values.

scholarly journals A Fibonacci Wavelet Method for Solving Dual-Phase-Lag Heat Transfer Model in Multi-Layer Skin Tissue during Hyperthermia Treatment

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2254
Author(s):  
Hari Mohan Srivastava ◽  
Mohd. Irfan ◽  
Firdous A. Shah
Keyword(s):  
Time Lag ◽  
Blood Perfusion ◽  
Bioheat Transfer ◽  
Transfer Model ◽  
Operational Matrices ◽  
Phase Lag ◽  
Dual Phase ◽  
Algebraic Equations ◽  
Hyperthermia Treatment ◽  
Wavelet Collocation Method

In this article, a novel wavelet collocation method based on Fibonacci wavelets is proposed to solve the dual-phase-lag (DPL) bioheat transfer model in multilayer skin tissues during hyperthermia treatment. Firstly, the Fibonacci polynomials and the corresponding wavelets along with their fundamental properties are briefly studied. Secondly, the operational matrices of integration for the Fibonacci wavelets are built by following the celebrated approach of Chen and Haiso. Thirdly, the proposed method is utilized to reduce the underlying DPL model into a system of algebraic equations, which has been solved using the Newton iteration method. Towards the culmination, the effect of different parameters including the tissue-wall temperature, time-lag due to heat flux, time-lag due to temperature gradient, blood perfusion, metabolic heat generation, heat loss due to diffusion of water, and boundary conditions of various kinds on multilayer skin tissues during hyperthermia treatment are briefly presented and all the outcomes are portrayed graphically.

How Bone Tissue and Cells Experience Elevated Temperatures During Orthopaedic Cutting: An Experimental and Computational Investigation

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Eimear B. Dolan ◽  
Ted J. Vaughan ◽  
Glen L. Niebur ◽  
Conor Casey ◽  
David Tallon ◽  
...  
Keyword(s):  
Bone Tissue ◽  
Orthopaedic Surgery ◽  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
A Priori ◽  
Computational Investigation ◽  
Bone Injury ◽  
Analytical Expressions ◽  
Insight Into

During orthopaedic surgery elevated temperatures due to cutting can result in bone injury, contributing to implant failure or delayed healing. However, how resulting temperatures are experienced throughout bone tissue and cells is unknown. This study uses a combination of experiments (forward-looking infrared (FLIR)) and multiscale computational models to predict thermal elevations in bone tissue and cells. Using multiple regression analysis, analytical expressions are derived allowing a priori prediction of temperature distribution throughout bone with respect to blade geometry, feed-rate, distance from surface, and cooling time. This study offers an insight into bone thermal behavior, informing innovative cutting techniques that reduce cellular thermal damage.

Understanding the Effects of Thermal Elevations Associated With Orthopedic Intervention: An Experimental and Computational Investigation

2013 ◽  
Author(s):  
E. B. Dolan ◽  
T. J. Vaughan ◽  
G. L. Niebur ◽  
D. Tallon ◽  
L. M. McNamara
Keyword(s):  
Bone Tissue ◽  
Computational Models ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Bone Cells ◽  
The Body ◽  
Surrounding Soft Tissue ◽  
Multi Scale ◽  
Orthopedic Surgeons

Specialized surgical cutting instruments are required to provide orthopedic surgeons with access to joints of the body, without causing extensive harm to native tissue, thus enhancing post-operative outcome. Orthopaedic intervention inevitably exposes bone tissue to elevated temperatures due to mechanical abrasion. Elevated temperatures lead to thermal necrosis and apoptosis of bone cells, surrounding soft tissue, bone marrow and stem cells crucial for postoperative healing (1–4). Thermally damaged bone tissue is subsequently resorbed and in severe cases replaced by connective tissue (2, 5) Bone thermal damage occurs when the local temperature exceeds a thermal threshold, largely recognised as ≥47°C (4, 6). Furthermore, it has been proposed that the area of bone to experience thermal damage is directly proportional to the duration of exposure to the heat source (7, 8). However, precise thermal elevations occurring throughout bone during surgical cutting are not well defined. It is also unclear whether temperatures generated in osteocytes in vivo are sufficient to induce cellular responses. Experimental analysis of temperature generation throughout bone is challenging due to its complex heterogeneous composition. There is a specific need for advanced 3D computational models that incorporate multi-scale variability in both bone tissue composition and thermal properties to predict how organ level thermal elevations are distributed throughout bone cells and tissue during orthopaedic cutting procedures.

Optimization of Multiprobe Cryosurgery

1992 ◽  
Vol 114 (4) ◽  
pp. 796-801 ◽  
Author(s):  
R. G. Keanini ◽  
B. Rubinsky
Keyword(s):  
Optimization Algorithm ◽  
Iterative Procedure ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Bioheat Transfer ◽  
Simplified Model ◽  
Transfer Model ◽  
Illustrative Case ◽  
Minimization Algorithm ◽  
General Technique

This paper describes a general technique for optimizing cryosurgical procedures. The method, which is based on the simplex minimization algorithm, minimizes unnecessary freezing by optimizing various surgical parameters. The optimization procedure is illustrated using a simplified model of prostatic cryosurgery. In this illustrative case, the function to be minimized, F, defined as the volume of healthy tissue destroyed during complete freezing of the prostate, is assumed to depend on three parameters: the number of cryoprobes used, the freezing length per cryoprobe, and the cryoprobe diameter. Using an iterative procedure, the optimization algorithm first alters these parameters, then calculates F by solving a three-dimensional bioheat transfer model of multiprobe cryosurgery, and finally determines whether F is minimized. The iterative procedure continues until unnecessary freezing is minimized. For the model considered here, the optimization code indicates that unnecessary freezing during cryoprostatectomy is minimized using approximately 5 cryoprobes, each 7.5 mm in length and 4 mm in diameter.

Transient Temperature During the Vaporization of Liquid on a Pulsed Laser-Heated Solid Surface

1996 ◽  
Vol 118 (3) ◽  
pp. 702-708 ◽  
Author(s):  
H. K. Park ◽  
X. Zhang ◽  
C. P. Grigoropoulos ◽  
C. C. Poon ◽  
A. C. Tam
Keyword(s):  
Thin Film ◽  
Solid Surface ◽  
Elevated Temperatures ◽  
Bubble Nucleation ◽  
Transient Temperature ◽  
Specular Reflectance ◽  
Transient Temperature Field ◽  
Excimer Laser Pulse ◽  
Nanosecond Time Resolution ◽  
Laser Heated

The thermodynamics of the rapid vaporization of a liquid on a solid surface heated by an excimer laser pulse is studied experimentally. The transient temperature field is measured by monitoring the photothermal reflectance of an embedded thin film in nanosecond time resolution. The transient reflectivity is calibrated by considering a temperature gradient across the sample based on the static measurements of the thin film optical properties at elevated temperatures. The dynamics of bubble nucleation, growth, and collapse is detected by probing the optical specular reflectance. The metastability behavior of the liquid and the criterion for the onset of liquid–vapor phase transition in nanosecond time scale are obtained quantitatively for the first time.

Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy

2017 ◽  
Vol 71 (12) ◽  
pp. 2626-2631 ◽  
Author(s):  
Jeffrey L. Wheeler ◽  
McKinley Pugh ◽  
S. Jake Atkins ◽  
Jason M. Porter
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Computational Models ◽  
Elevated Temperatures ◽  
Molar Absorptivity ◽  
Ir Absorption ◽  
Optical Cell ◽  
Multiple Samples ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

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