The 21st Birthday Party for intensity-modulated radiation therapy (IMRT); 21 years from 1988-2009; From concept to practical reality

Abstract

IMRT is now a major clinical specialty. It is a form of conformal radiation therapy which is specifically tailored to create a high-dose volume that matches the volumetric shape of the intended target region and simultaneously spares the nearby organs at risk. It is particularly competent for treating head-and-neck cancers, prostate, lung, breast and other targets where adjacent organs at risk are present. The development of IMRT is firmly rooted in physics and specifically the branch of physics known as medical physics. IMRT was "born" in about 1988 in that this was the year in which the pioneering paper on inverse planning for IMRT of Anders Brahme appeared. In the years immediately following, a small handful of workers, including the author, developed methods to plan and deliver IMRT. By the mid 1990s the main methods were established using phantom materials in University Hospitals. Clinical IMRT started in 1994 and, for a few years thereafter, commenced in a very limited number of specialist institutions. By the turn of the millennium the technique was beginning to be established more widely and in 2009 it is regarded as a clinical necessity for many tumour sites and has Worldwide popularity. This lecture will review this growth and present the main IMRT planning and delivery landmarks along the developmental path. The clinical rationale will be explained. Some pre-history will also be discussed. The technologies of multiple-static multileaf collimator IMRT, dynamic MLC IMRT, Tomotherapy, robotic IMRT, volume modulated arc therapy will be explained. Specific early planning systems will be mentioned. The role of the author's Centre in establishing clinical IMRT in the UK will be explained. Finally, as IMRT becomes a regularly used tool, attention will switch to combining 3D and 4D medical imaging with IMRT, so called IGRT, for taking care of organ motion. © 2009 Springer-Verlag.