Temperature Distribution In Tumor Research Articles

Mathematical Study of Two-Dimensional Temperature Variation in Tumor Embedded Breast Tissue

The human body is made by 100 trillion cells. The uncontrolled and abnormal growth of cells causes tumors. Due to the presence of tumor, the skin surface temperature of body provides abnormal behavior than normal. Most of the breast tumor develops in lobules and milk ducts of glandular layer. In this study, tumor is assumed in glandular layer. The study of this work is focused to find the temperature distribution in tumor embedded female breast tissue with different tumor location and different tumor size. For this, the finite element method is used to solve two-dimensional Pennes bio heat equation. The results show that the skin surface temperature of breast is higher with nearest tumor from areola. The temperature variation in breast tissue with tumors located at symmetrical position about the central line of the breast are identical.

Modelling the tumor temperature distribution in anatomically correct female breast phantom

Modelling the tumor temperature distribution in anatomically correct female breast phantom

On the temperature control in self-controlling hyperthermia therapy

In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature change pattern and temperature distribution in tumor and surrounding tissue are studied. After describing the model and its governing equations and constants precisely, a typical numerical solution of the model is presented. Then it is showed that how different parameters like Curie temperature of nanoparticles, magnetic field amplitude and nanoparticles concentration can affect the temperature change pattern during self-controlling magnetic hyperthermia. The model system herein discussed can be useful to gain insight on the self-controlling magnetic hyperthermia while applied to cancer treatment in real scenario and can be useful for treatment strategy determination.

Computational evaluation of amplitude modulation for enhanced magnetic nanoparticle hyperthermia.

Magnetic nanoparticles (MNPs) can interact with alternating magnetic fields (AMFs) to deposit localized energy for hyperthermia treatment of cancer. Hyperthermia is useful in the context of multimodality treatments with radiation or chemotherapy to enhance disease control without increased toxicity. The unique attributes of heat deposition and transfer with MNPs have generated considerable attention and have been the focus of extensive investigations to elucidate mechanisms and optimize performance. Three-dimensional (3D) simulations are often conducted with the finite element method (FEM) using the Pennes' bioheat equation. In the current study, the Pennes' equation was modified to include a thermal damage-dependent perfusion profile to improve model predictions with respect to known physiological responses to tissue heating. A normal distribution of MNPs in a model liver tumor was combined with empirical nanoparticle heating data to calculate tumor temperature distributions and resulting survival fraction of cancer cells. In addition, calculated spatiotemporal temperature changes were compared among magnetic field amplitude modulations of a base 150-kHz sinusoidal waveform, specifically, no modulation, sinusoidal, rectangular, and triangular modulation. Complex relationships were observed between nanoparticle heating and cancer tissue damage when amplitude modulation and damage-related perfusion profiles were varied. These results are tantalizing and motivate further exploration of amplitude modulation as a means to enhance efficiency of and overcome technical challenges associated with magnetic nanoparticle hyperthermia (MNH).

Magnetic Heating by Tunable Arrays of Nanoparticles in Cancer Therapy

Detailed knowledge about the temperature distribution achieved in the target area is essential for the development of magnetic hyperthermia treatments. However, the temperature inhomogeneity was found in all local hyperthermia studies. As a consequence of the impossibility of guaranteeing the temperature and thus the thermal dose distribution, hyperthermia is never applied as a single treatment modality. We suggest a model that enables the calculations and optimization of the spatial-time distribution of the temperature in the target volume (i.e. tumor) caused by magnetically heated elements: (i) arrays of clusters of iron oxides magnetite (Fe3O4) magnetic nanoparticles, and (ii) arrays of magnetic needles. In order to find the spatial-time temperature distribution in tumor, the bioheat transfer equation is solved for the two above-mentioned arrays of magnetically heated sources embedded in the tumor. The temporal and spatial temperature distributions were calculated with regard to the effect of blood perfusion in the tumor. It is shown that a matrix of magnetic micro-needles injected in the tumor could provide rather uniform tumor heating with the center-edge temperature difference smaller than 3◦C at any times during the magnetic hyperthermia treatments. The temperature profiles can be suitably adjusted by a proper choice of the magnetic nanoparticles arrangement.

The BECM concepts applied to heal cancer

The application of Bio-Electric Circuits Model (BECM) concepts can destroy cancer cells. Complete Response (CR)+Partial Response (PR) of about 80% was obtained in more than three thousand cases from different types of human cancer. We agree that the treatment of cancer using the concepts of BECM utilizes the same principle as that of hyperthermia techniques in cancer therapy. This paper estimates the tumor temperature distribution when the BECM is applied in the cancer area. The Finite Element Method (FEM) is used to determine the temperature distribution inside the human model caused by the application of BECM in the tumor region. The simulation of the use of BECM in a tumor situated in the thorax region is presented. The aim of this work is to present a new hyperthermia technique where DC current is used directly in the tumor (contrary to irradiating the cancer area with high frequencies) to determine the temperature distribution of this area.

Inverse techniques in hyperthermia: a sensitivity study.

Numerical modeling methods and hyperthermia treatment temperature measurements have been used together to reconstruct steady-state tumor temperature distributions. However, model errors will exist which may in turn produce errors in the reconstructed temperature distributions. A series of computer experiments was conducted to study the sensitivity of reconstructed two-dimensional temperature distributions to perfusion distribution modeling errors. Temperature distributions were simulated using a finite element approximation of Pennes' bioheat transfer equation. Relevant variables such as tumor shape, perfusion distribution, and power deposition were modeled. An optimization method and the temperatures "measured" from the simulated temperature distributions were used to reconstruct the tumor temperature distribution. Using this procedure, the sensitivity of the reconstructed tumor temperature distribution to model-related errors, such as the perfusion function, was studied. It was found that: 1) if the problem is conduction dominated, large errors in the perfusion distribution produce only small errors in the reconstructed temperature distribution (maximum error < 1.0 degrees C), and 2) when the actual perfusion distribution contains a small random variation (+/- 15%) which is neglected by the model, the reconstructed temperature distribution will be in good agreement with the actual temperature distribution (maximum error < or = 0.3 degrees.

Hyperthermia in the Management of Lung Cancer: The Current Situation

It is technically difficult to heat tumors in the thorax. Whole body heating gives the best tumor temperature distribution but is limited to 42°C, while external RF heating is uncertain. Implant techniques may be worth developing to overcome some of these problems. Hyperthermia alone is ineffective and needs to be combined with radiotherapy or chemotherapy. Does hyperthermia have a place in the management of lung cancer? As clinical results remain largely anecdotal, it can only be recommended as an experimental technique to be studied within the framework of well-designed clinical trials.

Numerical simulation of magnetic induction heating of tumors with ferromagnetic seed implants.

Calculations based on the bioheat transfer equation have been carried out to determine the temperature distributions to be expected from the use of inductively heated ferromagnetic implants to heat deep-seated tumors. Two types of ferromagnetic implants are considered: constant power seeds, for example, those constructed from Type 430 stainless steel; and constant temperature seeds which pass through a Curie transition to the nonmagnetic state at a specified temperature. The temperature distributions are studied as a function of the size of the implant array, its geometrical relationship to the tumor, the density of implants within the array, and the blood perfusion characteristics of the tumor and its surrounding normal tissue. Two tumor models are considered: a uniformly perfused model which is indistinguishable from the surrounding normal tissue, and an annular perfusion model with a necrotic core surrounded by intermediately and highly perfused shells. Temperature distributions are considered acceptable if the minimum temperature in the tumor is greater than 42°C and the maximum temperature does not exceed a maximum allowable value (either 48 or 60°C). The results of over 200 combinations of the above parameters are presented in a compact format. General conclusions drawn are that the tumor should lie entirely within the implanted array if the tumor periphery is to be heated adequately, and that the constant temperature seeds, which are self-regulating in temperature, give better tumor temperature distributions.

Inference of complete tissue temperature fields from a few measured temperatures: an unconstrained optimization method.

In clinical applications of hyperthermia, tissue temperature measurements are made at only a few selected locations because of patient tolerance and practical clinical limitations. Since it is necessary to know the complete tumor temperature field in order to effectively evaluate a treatment, methods of interpolating and extrapolating must be developed to estimate the unmeasured tumor temperatures. The difficulty of making such estimates from only a few data points is compounded by a lack of knowledge of the tumor blood perfusion characteristics. To solve this problem we have developed an iterative state and parameter estimation algorithm to attempt to estimate complete tissue temperature fields from temperatures measured at selected locations when tissue perfusion values are unknown. This approach uses either a conjugate gradient or a relaxation method to minimize the difference between the measured temperatures and the temperatures predicted at those same locations by the bioheat transfer equation. To investigate the mathematical capabilities and limitations of this technique a sensitivity analysis has been performed by applying it to a large number of simulated one-dimensional hyperthermia treatments. To illustrate its applicability to clinical situations, the estimation algorithm is also applied to temperature measurements from an animal experiment. The simulation results show that the technique is promising for estimating the complete tumor temperature distribution from measurements at a small number of sampled locations, if some knowledge of the blood perfusion pattern is available.

Uniform regional heating of the lower trunk: Numerical evaluation of tumor temperature distributions

The temperature distributions in deep seated tumors resulting from uniform heating of the abdominal and pelvic regions of the trunk are predicted from a one dimensional numerical solution of the bio-heat transfer equation. The effect of tumor size and location are investigated for two tumor perfusion models: uniform perfusion and a concentric annulus perfusion model. Tumor temperature distributions are considered acceptable if the range of temperatures in the tumor lie between 42°C and 60°C. This range of tumor temperatures is defined as T ave ± 2a where o is the population standard deviation of tumor temperatures from the average computed at the nodal points in the finite difference array. To simulate practical clinical restrictions, muscle and fat temperatures are not allowed to exceed 44°C, significant portions of the viscera are not allowed to exceed 42°C, and the total absorbed power required to maintain steady state cannot exceed two kilowatts. Over 100 possible cases are presented in a compact form. From this study it appears that heating systems with power deposition patterns approximately uniform are promising for heating deep-seated tumors. Small, detectable tumors (approximately 2 cm in size) are adequately heated for a wider range of conditions than are larger tumors. Excessively high temperatures in deep-seated, normal tissue could be a significant limitation for this technique.

Magnetic induction heating of tissue: Numerical evaluation of tumor temperature distributions

A one dimensional (radial) numerical model based on the bioheat transfer equation has been developed and applied to the abdomen and pelvis heated by a concentric magnetic induction electrode. This model consists of four normal tissue regions: viscera, muscle, fat and skin. Each region is assigned thermal properties characteristic of that region and power deposition values consistent with those for this mode of heating. Tumors of 2, 4 and 7 cm thicknesses are positioned in five different radial locations ranging from the central axis to the skin surface. Two blood perfusion models of the tumor are considered: the uniformly perfused model and an annular model. Tumor temperature distributions are considered acceptable if the average tumor temperature plus and minus two standard deviations lie between 42°C and 60°C. To simulate practical clinical restrictions, muscle and fat temperatures are not allowed to exceed 44°C, significant portions of the viscera (except for a 1 cm thick band) are not allowed to exceed 42°C, and the total absorbed power required to maintain steady state cannot exceed one kilowatt. Over 100 possible cases are presented in a compact form. A conclusion drawn from this study is that with few exceptions, only small tumors in the muscle annulus are heated adequately with this modality. Large tumors will have significant unheated portions if the specified limitations are not exceeded. While this heating modality can raise the necrotic core of a tumor to high temperatures, it cannot adequately heat well perfused regions of a deep seated tumor. These conclusions are borne out clinically and are discussed in a companion paper.