The technical advances that have been achieved over the last decade in the area
of 3－dimensional radiotherapy treatment planning capabilities and new and more flexible hardware capabilities, such as computer－controlled treatments, multileaf collimators, and real－time portal imaging devices, have brought about 3－dimensional conformal radiation therapy. For the purpose of highly conformal radiation therapy, a variety of radiation treatment techniques and treatment machines such as stereotactic radiosurgery(SRS) using gamma－knife, stereotactic radiotherapy(SRT) using linear accelerator, and stereotactic whole body radiotherapy have been invented. Intensity－modulated radiation therapy(IMRT) is a new and evolving technological advance in high－precision radiation therapy. It is an extension of 3－dimensional conformal radiotherapy(3－DCRT) that allows the delivery of highly complex isodose profiles to the target, while minimizing radiation exposure to surrounding normal tissues. Image－guided adaptive radiotherapy(IGRT) combines scanning and radiation equipment, to provide images of the patient’s organs in the treatment position, at the time of the treatment, optimizing the accuracy and precision of the radiotherapy. Respiratory－gated radiotherapy was developed to overcome the motion of organs. Most high precision radiation therapy approaches increase the time and efforts required by physicians and physicists, because optimization systems are not yet robust enough to provide automated solutions for all disease sites, and routine QA
testing is still quite time－consuming. Preliminary clinical experiences of high precision
radiation therapy have been encouraging by high rates of local control and decrease of toxicity. This article provides an overview of high precision radiotherapy such as 3－DCRT, SRS, SRT, Cyberknife, IMRT, and IGRT.
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