The four authors continuing the pioneering work of Frank Attix, Prof Pedro Andreo (Karolinska, Stockholm), Dr David T. Burns (BIPM, Paris), Prof Alan E. Nahum (University of Liverpool) and Prof Jan Seuntjens (McGill University, Montreal), are leading scientists in radiation dosimetry, having published between them more than 600 papers in the field. They have co-authored most of the existing national and international recommendations for radiotherapy dosimetry and received a number of international awards for their contributions.