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 vivo measurements, which are generally not used systematically for all patients and all fractions, record and verify (R and V) systems ensure that the machine settings will 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).