The technologies of delivering IMRT in slices are known as rotation IMRT or tomotherapy. Purists may argue about the precise terminology but serial tomotherapy (MIMiC-based) and spiral tomotherapy (University of Wisconsin machine-based) are related and usually reviewed together. The history of what interaction there might be considered to be was best reviewed by Mackie et al (2003b). The concept of the binary modulator for slit-field radiation was first proposed by Swerdloff in Mackie’s group in 1988. This led to the patent for the multivane intensity-modulating collimator (MIMiC) being held by the University of Wisconsin Alumni Research Foundation (WARF) and licenced to NOMOS who first made it a practical reality in 1992. The idea of spiral tomotherapy did not come until about 1992 when spiral CT became possible and Mackie saw the opportunity to reuse a gantry for this purpose. By then the NOMOS MIMiC was a reality (NOMOS is now part of North American Scientific). It was another 10 years before the spiral tomotherapy unit, a much grander engineering venture, became commercially available.