What is stereotactic radiotherapy?

The concept of stereotactic radiosurgery has become a reality with the invention of gamma knife and good therapeutic effect, and it has become a new concept and a new branch of stereotactic radiosurgery with the invention of gamma knife and good therapeutic effect. Around the concept of stereotactic radiosurgery, the inventions of different medical instruments and new technologies emerge one after another. In 1980s, Colombo, Betti and other scholars improved the medical linear accelerator, added a stereotactic system and a collimator, and used a non-* * plane multi-radian Xiaoye three-dimensional beam to irradiate the focus, achieving a therapeutic effect similar to that of gamma knife. This improved linear accelerator is called X-knife. Generally, staged treatment is adopted, which is called stereotactic radiotherapy (SRT) in academic circles. Three-dimensional conformal radiotherapy (3D CRT) and intensity modulated radiotherapy (IMRT) techniques of linear accelerator, whole-body gamma knife and body gamma knife, which gradually matured in 1990s, belong to the category of stereotactic radiotherapy. It is characterized by stereoscopic, lobular, bunching, grading and high dose irradiation. According to the size of single dose and the degree of beam cluster, SRT is currently divided into two categories. The first type of SRT is characterized by three-dimensional, Xiao Ye, bunching, fractional and large dose (much larger than the conventional fractional dose) irradiation. This kind of multi-arc non-planar rotating focusing technology is adopted, and the additional three-pole collimator is generally round. Generally, X-knife, whole-body gamma knife and whole-body gamma knife all belong to this category, but in the case of skull fixation and single large-dose treatment, X-knife can be called SRS. The second type of SRT is conventional fractionated radiotherapy using stereotactic technique. 3DCRT, especially IMRT, falls into this category. Stereotactic radiotherapy and stereotactic radiosurgery are two confusing concepts. They have both similarities and obvious differences. Similarly, under stereotactic orientation, the irradiation dose in the target area is increased as much as possible by different techniques, and the dose of tissues outside the target area is reduced. The difference mainly lies in the accuracy of positioning and the degree of dose attenuation outside the target area. The error of SRT is larger than SRS, and the radiation dose attenuation outside the target area is not as steep as SRS. It is precisely for this reason that SRT has not reached the level of "surgery", which determines that SRT is a multiple high-dose treatment (greater than conventional radiotherapy and less than SRS), while SRS is a one-time high-dose treatment.