ABSTRACT
The goal of the optimization in brachytherapy is to generate treatment plans that result in delivering a sufficiently high dose to the planned target volume (PTV) while sparing the surrounding organs at risk (OARs) and normal tissues (NTs) as much as possible. Electronic brachytherapy uses a miniature x-ray source instead of a radioactive one for high-dose rate (HDR) brachytherapy. Dose optimization aspects of electronic brachytherapy are dependent on the type of equipment. With equipment for skin treatment, no dwell time optimization takes place, while for volume implants, the x-ray source is stepping through one or more catheters and planning optimization techniques remain largely similar compared to radioactive sources. The use of tumor control probability (TCP) and normal tissue control probability (NTCP) for dose optimization is not yet clinically applicable on a routine basis. Radioembolization uses microspheres loaded with a radioactive isotope for the treatment of hepatic malignancies.
