Four ways of optimizing laser-assisted treatments in hollow organs are proposed in this paper: 1. For coagulation in axial direction at small irradiation distances fiber tips with enhanced divergence increase the coagulation volume and reduce vaporization. 2. Circumferentially complete coagulation of cylindrical organs can be achieved by using a radially radiating probe. 3. Radiators for photodynamic therapy in cylindrical organs can be constructed and optimized by means of a theoretical scattering model. 4. Isotropic radiators based on conical fiber tips improve the radiation into the rear hemisphere.