Chemistry+Applications+Essay+46

The Chemistry of Radiation Therapy Radiation therapy, officially introduced to treatment facilities as early as 1936, revolutionized the method for cancer treatment worldwide. But, many people are unaware of how exactly it works on a microscopic level. As its name implies, the Radiation therapy is centered around the use of electromagnetic radiation, x-ray and gamma ray, to target and destroy cancerous tumor cells.

X-rays and gamma rays are the only forms of radiation useful in radiation therapy. This is for several scientifically proved reasons. Both have a high frequency and a short wavelength. Because of this, they are able to pass through human tissue. Both x-rays and gamma rays have a special factor that causes them to be harmful to cells: they are forms of ionizing radiation. This means that the photons have the ability to eject an electron from their orbit in an atom. This factor is a great contributor as to why x-ray and gamma ray radiation are able to harm and kill cells. Using ionizing radiation to diagnose medical conditions is a widespread practice that is constantly increasing due to newer applications in healthcare.

These harmful forms of radiation primarily kill cells by attacking their DNA, causing a wide range of lesions. These lesions are in several different areas of the helix, including phosphodiester bonds and nucleotide base pairs; proteins in other areas of the cell can also be damaged. Cancer cells are regarded as “dead” when they have lost the ability to reproduce, not necessarily by if they continue to exist in the body. The rate of response to the radiation depends on how quickly the cells divide. By studying how rapidly the cells are killed, they can be classified as either radiosensitive or radioresistant. Radiosensitive means the tumor is regressing quickly. If the tumor has a high number of rapidly dividing cells, they will express radiation damage at an early stage and the tumor will regress rapidly. A tumor is radioresistant if it regresses slowly. X-ray and gamma ray radiation can also destroy a cell by interacting with the water it contains, which is about eighty percent of a cell’s volume. By interacting with water, the radiation generates free radicals within the cell. Free radicals are chemical entities that do not have a stable amount of electrons in the outer shell. Free radicals are unstable, with a life of only fractions of a second. Most of the cell damage from x-rays is caused by the formation of hydroxyl radicals.

There are two types of treatment methods in radiation therapy: external and internal. During the external beam radiation method, the patient is given a small amount of the normal dose each time and the treatments are administered in increments spread out over several weeks. The radiation, as its name implies, penetrates the body from the exterior. The most effective method is when several beams, each coming from a different direction, are used simultaneously. The beams are precisely focused to come together and meet at an exact point, this point being the tumor. Advanced computer simulation technology aids in determining the placement of these beams in regard to their position about the patients body. On the other hand, internal radiation uses radioactive material sealed in a thin wire, catheter, or tube, which is then directly implanted into the tumor. This method of treatment is also called brachytherapy. There are several different isotopes to choose from to put in the capsule, including radium-226, cesium-137, cobalt-60, iridium192, iodine-125, gold-198 and palladium-103. The radium isotope in the past was the most used isotope in brachytherapy. Due to it’s longer half-life, isotopes with a shorter half-life quickly replaced it. By using this direct implantation of a capsule, this focuses the radiation directly on the cancer cells and decreases the radiation damage of non- cancerous tissue.

Radiation therapy was a breakthrough in medical history and has proved itself extremely beneficial. It is minimally invasive, painless, and has a shorter recovery time than previous methods of cancer treatment. It has completely transformed the field of oncology for the better, and with today’s rapidly improving technology and continual advances in research, radiation therapy holds an even more promising future.

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