The record and verify system is computer software that checks the position of the couch, collimator, gantry and any beam modifiers before a treatment is given. The components of this system are:
- Links with the treatment planning system (to compare data with the treatment plan)
- Links with the control system of the linear accelerator (often the R&V system is part of the control system)
- Accurate positioning information from the linear accelerator, including the couch, gantry, collimator, accessory tray, independent jaws, multileaf collimators and ionisation chambers (and numerous other recording devices)
- Display of this information
- Manual data entry (for quantities the machine can't measure, such as SSD)
- A username/password entry so staff can authorise a treatment
Most record and verify systems have tolerance levels built into them. These allow some parameters to be allowable as long as they are within a certain range of the expected value. Different parameters have different tolerance levels. If a parameter is grossly different from expected, then the patient's position often needs to be altered, or the reason for the shift identified (maybe due to loss of weight with head and neck treatment). If the shift can not be corrected, replanning may be needed.