R


R


Radiation therapy


Description


Radiation therapy is one of the oldest methods of cancer treatment. Delivery of high-energy beams, when absorbed into tissue, produces ionization of atomic particles. The energy in ionizing radiation acts to break the chemical bonds in DNA. The DNA is damaged, resulting in cell death.


Different types of ionizing radiation are used to treat cancer, including electromagnetic radiation (i.e., x-rays, gamma rays) and particulate radiation (alpha particles, electrons, neutrons, protons). High-energy x-rays (photons) are generated by an electric machine, such as a linear accelerator.



■ The nomenclature for radiation dose is gray (Gy) or centigray (cGy). A centigray is equivalent to 1 rad, and 100 centigray equals 1 gray.


■ Once the total dose to be delivered is determined, that dose is divided into daily fractions. Doses between 180 and 200 cGy/day are considered standard fractionation, typically delivered once a day Monday through Friday for a period of 2 to 8 weeks (depending on the desired total dose).


■ Radiation only has an effect on tissues within the treatment field. It is not appropriate as the primary treatment for systemic disease. However, radiation may be used by itself in combination with chemotherapy or surgery to treat primary tumors, or for palliation of metastatic lesions.


■ Radiation can be delivered externally (known as teletherapy or external beam radiation therapy) or internally (brachytherapy).

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Oct 26, 2016 | Posted by in NURSING | Comments Off on R

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