Hyperthermia

For a long time researchers have been interested to use heat as a treatment for cancer. Hyperthermia (also called thermal therapy or thermotherapy) is one of cancer treatment processes in which body tissues containing tumor is exposed to high temperatures (up to 42 degree Celsius). This treatment is usually used with other forms of cancer therapy, such as radiation therapy and chemotherapy. Microwaves, laser and ionizing radiation are the most common methods which are used in hyperthermia. These methods are mainly used for heating and eliminating superficial tumors on the skin. Magnetic hyperthermia is one of the novel techniques in thermotherapy which has drawn a lot of attention. It is theoretically based on the fact that magnetic nanoparticles can transform electromagnetic energy from an external high-frequency field to heat. Magnetic nanoparticles that are used for thermotherapy can be ferromagnetic. For medical applications, these particles must be innocuous, biologically compatible with the body, as well as have a natural pH and be soluble in water. The carrier fluids of magnetic particles are usually water or hydrocarbons. Magnetic nanoparticles like permanent magnets have magnetic spins which align in the same direction. In order for magnetic spins to align randomly, a variable magnetic field is used to provide the required energy. This energy can be converted into heat. The generated energy resulting from change in spins direction is used to create heat inside the living cells. Moreover, the friction created by the rotation of the magnetic nanoparticles inside the fluid with high viscosity and concentration can generate heat until reaching the physical equilibrium state. Thus, the basis of this method involves the direct injection of magnetic fluids containing magnetic nanoparticles into cancerous tumors and the generation of heat based on the aforementioned mechanism. When a patient is exposed to a variable magnetic field at frequencies close to the FM radio signal, magnetic nanoparticles can kill the cancerous tumor by creating heat. Inappropriate distribution of heat in all tumor cells, inadequate amount of produced heat and unwanted thermotherapy of healthy cells are the most important challenges of current hyperthermia methods.