ABSTRACT
To improve the accuracy of treatment delivery, by eliminating as many errors as possible,
checking systems, whether human or computer-assisted are commonly used on radiotherapy
treatment machines (Rosenbloom et al. 1977; Klein et al. 1998). Errors can either be caused by
human fallibility or machine malfunction, so interlock and checking systems have been devised
to help reduce these errors. In contrast with portal imaging and in vivomeasurements, which are
generally not used systematically for all patients and all fractions, record and verify (R and V)
systems ensure that themachine settingswill be repeated throughout the treatment course. They
also ensure that the programmed total dose will not be exceeded. This places a considerable
burden on the person entering the data for the first time, as any errors may be repeated
throughout the treatment (see Section 41.2.2).
