The role of a conventional simulator in multileaf-plan simulation: A proposal

Modern computer networks provide satisfying levels of data recording and ve rification between the treatment planning system (TPS) and the accelerators , while the main weakness of the preparation chain remains the simulation. When a conventional simulator is employed, it may adversely affect the thre e-dimensional treatment planning system (3DPS) process because of the diffi culty to document the leaf positions on the simulator location films and on the patient's skin. With a conventional simulator, hard copies of the DRRs of each field and CT scans at isocenter level are needed. In an attempt to transfer more information displayed from a BEV perspective from the 3DPS to simulator radiographs, this study aimed to reduce the qua lity loss by using a 2D conventional simulator in a 3DPS process. We realized an acetate photocopy of TPS data for each field, from a BEV per spective, containing: DRR, wire frames of the PTV, organs at risk and MLC a perture. The photocopies, with an appropriate magnification factor to obtai n a correct projective value (ratio 1:1) at isocenter level, are carefully placed on the radiographic images on the same hard copy which allows us to better understand possible setup errors and obliges us to correct these. The method provides reliable documentation, facilitates treatment verificat ion, and fulfils the criteria for MLC simulation. It is accurate, simple, a nd very inexpensive.