MEDICAL RADIATION THERAPIES

Abstract

Historically speaking, medical radiation therapy is a relatively old medical branch as it originated two centuries ago with the discovery of x-radiation by W.C. Rontgen in 1895. Shortly after this historical event the first treatment attempts were carried out by some courageous physicians. Since then radiation therapy evolution has undergone several major leaps due to essential developments in mechanical engineering, electronics, and computer science. An introductory part gives an overview of these developmental steps through history. This is followed by some basic information on the physical and technological principles of radiation physics. Here radiation types, radiation sources, and the interaction of radiation with biological tissue are covered and finally rounded out with a more detailed look at dosimetry. Furthermore, the three therapy fields for radiation treatments are discussed: percutaneous therapy, brachytherapy, and radionuclide therapy. The main part covers equipment technology for the generation of radiation. In radiation therapy, ionizing radiation is used, which either results from radioactive decay processes or is generated by the acceleration of charged particles. The technologies described are x-ray equipment, cobalt unit, linear accelerator, brachytherapy sources/treatment units, and radioactive implants. A main focus is on the technology of linear accelerators, which serve as the daily workhorses nowadays. Finally, special techniques and newer developments in teletherapy are discussed. Besides stereotactic and tomotherapy approaches, technological developments and refinements in the field of linear accelerator technology are described in more detail.