A column generation approach to intraday scheduling of chemotherapy patients

Chemotherapy scheduling at cancer treatment centres is a complex problem due to high and growing demand, diversity of treatment protocols, limitations on resources and the need to coordinate treatment session times with laboratory preparation of medication. Over a given planning horizon, treatment centres assign patients first to specific days (interday scheduling) and then to specific times within each day (intraday scheduling), the latter process including the definition of medication preparation time. This paper addresses the intraday scheduling problem using an integer programming model that attempts to schedule all patients assigned to the horizon, and the preparation of the medication to be administered, simultaneously. The linear relaxation of the model formulation, which is based on treatment patterns, is solved using column generation. The proposed approach allows for medication preparation on the day of treatment or a previous day subject to time slot availability. A case study is conducted using actual data from a Chilean cancer centre to compare through simulation the schedules generated by the proposed approach and the centre's manual method. The results show that the proposed approach performs better on makespan, treatment chair occupancy, number of overtime hours and finding solutions at high demand levels.