Source of Support: None, Conflict of Interest: None
Interstitial brachytherapy as a treatment modality for the malignant lesions is gaining increasing interest. Tables and nomographs have been suggested and are being used for manual dosimetry. In this paper
some empirical equations are suggested for the computation of basal dose-rate (BDR) for standard single and double plane implant geometry based on Paris system. These equations, however, can also be used for finding the inter-source spacing or inter-plane spacing for a given linear activity and reference dose-rate to get the optimal implant geometry.