Book excerpt: This publication is intended as a guide for the clinical commissioning of radiotherapy treatment planning systems (RTPSs) and provides a simple protocol for these tasks. The procedures for clinical commissioning tests cover typical treatment techniques used in the radiotherapy hospitals and are based on the use of a specific phantom. The purpose of this testing is twofold. Firstly, the tests will provide an educational opportunity for the user to become familiar with the operation of the RTPS. Secondly, the tests will demonstrate to the user that the logistic chain starting from CT scanning, anatomic modelling, treatment planning and MU calculation is operable and leads to the desired results with sufficient accuracy.