A computerized dosimetric database for conformal stereotactic irradiations

An innovative computerized dosimetric database (DDB) is proposed to enable the analysis of the stereotactic radiosurgical dose distributions; it contains relationships between the irradiation parameters and the dose-volume data. Dose-volume data provide guidance to the physicist-physician team by facilitating the initialization of the irradiation parameters and the treatment planning. The presented DDB contains dose-volume data such as the 70% isodose widths and the 70%-30% isodose penumbra along the right-left, anterior-posterior, and superior-inferior directions as a function of the irradiation parameters defined by the user. In order to demonstrate the usefulness of the DDB, the effects of the collimator diameter, the number of arcs, and their length on the shape of the prescription isodose surface are shown and are related to practical considerations for the treatment plan. However, the presented DDB is one example that can be generated by the DDB system. The planner can define as many different DDBs as he/she wishes, which can then be used for different investigations. This type of DDB enables us to investigate the irradiation technique used, to compare different irradiation techniques, to inspect the feasibility of planning different lesion types, or to define some dosimetric rules. The DDB provides useful interactive guidelines for the treatment planning process and replaces the voluminous dosimetric atlas. It has now been in clinical use for a year in a conformal procedure which automatically proposes collimator diameters, arc positions, and lengths allowing rapid conformal planning.