This report gives guidance for commissioning and subsequent quality assurance of the networked radiotherapy department. It examines common issues for network commissioning and testing, gives comprehensive guidance on hospital IT issues (including network and data security) and examines specific functional aspects along a typical patient pathway; from patient data acquisition and treatment planning/definition, right through to treatment delivery and verification. The guidance is structured so the user can select the sections most relevant to the part of the radiotherapy network being tested. The report will be of interest to all healthcare professionals (particularly physicists, IT professionals, technologists and radiographers) involved in commissioning, testing and implementing the electronic passage of data throughout the radiotherapy department.