ABLATION

Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. The term occurs in space physics associated with atmospheric reentry, in glaciology, medicine and passive fire protection.

ABLATION IN MEDICINE

In medicine, ablation is the same as removal of a part of biological tissue, usually by surgery, and more recently using other modalities such as radiofrequency ablation and cryoablation. The American Heritage Stedman's Medical Dictionary defines ablation as "Removal of a body part or the destruction of its function, as by a surgery, disease, or noxious substance.

SURFACE ABLATION

i.)Surface ablation in the skin (also called resurfacing, because it induces regeneration) can be carried out by chemicals (peeling) or by lasers. Its purpose is to remove skin spots, aged skin, wrinkles, thus rejuvenating it.



ii.) Surface ablation is also employed in otolaryngology for several kinds of surgery, such as for snoring.



iii.)Ablation therapy using radiofrequency waves on the heart is used to cure a variety of cardiac arrhythmias such as supraventricular tachycardia, Wolff-Parkinson-White syndrome, ventricular tachycardia and more recently atrial fibrillation.



The term is often used in the context of laser ablation, a process by which the molecular bonds of a material are dissolved by a laser.



ROTOABLATION

Rotoablation is a type of arterial cleansing that consists of inserting a tiny, diamond-tipped, drill-like device into the affected artery to remove fatty deposits or plaque. The procedure is used in the treatment of coronary heart disease to restore blood flow.



BONE MARROW ABLATION

Bone marrow ablation is a process whereby the human bone marrow cells are eliminated in preparation for a bone marrow transplant. This is performed using high-intensity chemotherapy and total body irradiation.

GENETIC ABLATION

Genetic ablation is potentially a much more efficient method of removing unwanted cells, such as tumor cells, because large numbers of animals lacking specific cells could be generated. Genetically ablated lines can be maintained for a prolonged period of time and shared within the research community. Researchers at Columbia University report of reconstituted caspases combined from C. elegans and humans, which maintain a high degree of target specificity. The genetic ablation techniques described could prove useful in battling cancer.

LASER ABLATION

Laser ablation is greatly affected by the nature of the material and its ability to absorb energy, therefore the wavelength of the ablation laser should have a minimum absorption depth. While these lasers can average a low power, they can offer peak intensity and fluence given by:





while the peak power is



LASIK / LASEK LASER SYSTEM



Surface ablation of the cornea for several types of eye refractive surgery is now common, using an excimer laser system (LASIK and LASEK). Since the cornea does not grow back, laser is used to remodel the cornea refractive properties, in order to correct refraction errors, such as astigmatism, myopia and hyperopia.
(LASIK-------->Laser in-situ keratomileusis)