Comparative measurements on a series of accelerators by the same vendor

A series of comparative measurements were conducted during a 12-month perio d on a series of linear accelerators made by the same vendor. These measure ments were conducted during acceptance and commissioning of six Varian mode l 2100C linear accelerators which had identical beam energies and beam modi fiers. Nominal accelerating potentials, scatter measurements, depth doses, beam profiles, wedge and electron beam descriptors are presented. The resul ts show highly similar beam parameters with observed variations being appro ximately equivalent to the precision of measurement. This similarity implie s that a standard data set can be used to validate new commissioning data. (C) 1999 American Association of Physicists in Medicine. [S0094-2405(99)001 12-1].