Laser and its medical applications
The Advent of the "Laser Scalpel"
Early experimenters with medical lasers pointed out that there are surgical operations that are difficult to perform with the conventional scalpel and that a laser beam might be used instead. Initial trials showed that a finely focused beam from a carbon dioxide gas laser could cut through human tissue easily and neatly. The surgeon could direct the beam from any angle by using a mirror mounted on a movable metal arm. Several advantages of laser surgery quickly became apparent. First, the light beam is consistent, which means that it gives off the same amount of energy from
In this photo taken during open-heart surgery, a doctor uses a laser probe to punch small holes in the patient's heart muscle to increase the organ's blood flow. one second to the next. So as long as the beam is moving along, the cut it makes (the incision) does not vary in depth; whereas when using a scalpel a doctor can accidentally make part of the incision too deep. A second advantage of the surgical laser is that the hot beam cauterizes, or seals off, the open blood vessels as it moves along. (This works well mainly for small vessels, such as those in the skin. The doctor still has to seal off the larger blood vessels using conventional methods.) Still another advantage is that the cells in human tissue do not conduct heat very well, so the skin or any other tissue near the laser incision does not get very hot and is not affected by the beam. This advantage of laser surgery is very helpful when a doctor must operate on a tiny area that is surrounded by healthy tissue or organs. It should be pointed out that the "laser scalpel" is not necessarily the best tool to use in every operation. Some doctors feel that while the laser is useful in some situations, it will never totally replace the scalpel. Others are more optimistic and see a day when more advanced lasers will make the scalpel a thing of the past. The second of these views may prove to be the most accurate, for surgical use of lasers is rapidly advancing. At first, lasers were considered most effective in operating on areas that are easy to reach—areas on the body's exterior, including the skin, mouth, nose, ears, and eyes. But in recent years doctors have demonstrated remarkable progress in developing laser techniques for use in internal exploration and surgery. Of course, in order to be able to direct the laser beam the doctor must be able to see inside the body. In some cases this is a simple matter of making an incision and opening up the area to be operated on. But there are situations in which this step can be avoided. Cleaning Arteries with Light
For instance, lasers are increasingly used to clean plaque from people's arteries. Plaque is a tough fatty substance that can build up on the inside walls of the arteries. Eventually the vessels can get so clogged that blood does not flow normally, and the result can be a heart attack or stroke, both of which are serious and sometimes fatal. The traditional method for removing the plaque involves opening the chest and making several incisions, a long and sometimes risky operation. It is also expensive and requires weeks for recovery. An effective alternative is to use a laser beam to burn away the plaque. The key to making this work is the doctor's ability to see inside the artery and direct the beam, another area in which fiber optics and lasers are combined into a modern wonder tool. An optic fiber that has been connected to a tiny television camera can be inserted into an artery. These elements now become a miniature sensor that allows the doctor and nurses to see inside the artery while a second fiber is inserted to carry the bursts of light that will burn away the plaque. The technique works in the following way. The fiber-optic array is inserted into a blood vessel in an arm or leg and moved slowly into the area of...
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