TROTS - The Radiotherapy Optimisation Test Set. The Radiotherapy Optimisation Test Set (TROTS) is an extensive set of problems originating from radiation therapy treatment planning [1,2]. When a patient is diagnosed with cancer and selected for treatment with radiation therapy, a so-called treatment plan has to be generated. This is based on a 3D or 4D Computer Tomography (CT) scan of the patient. The treatment plan describes the personalised settings of the applied treatment unit, and contains a predicted patient dose distribution for these settings, projected on the planning CT-scan. The delivered dose distribution determines both the probability for cure and also the probability of damage to healthy tissues. The aim is to deliver sufficient dose to the tumour for curation, while keeping the dose to healthy organs as low as possible to minimise the probability of developing radiation-induced treatment related complications. More background information can be found on the pages of Radiation oncology and the website of Sebastiaan Breedveld.