A possible hazard is delivery of too much radiation to a patient. This can arise because of a system failure where a dose greater than the specified dose is delivered or an operator failure where the dose to be delivered is wrongly input.
Software features that may be included to guard against system failure are the delivery of radiation in increments with a operator display showing the dose delivered and the requirement that the operator confirm the delivery of the next increment. To reduce the probability of operator error, there could be a feature that requires confirmation of the dose to be delivered and that compares this to previous doses delivered to that patient. Alternatively, two different operators could be required to independently input the dose before the machine could operate.