The Clinical Possibility to Make Use of P++ Strategy to Obtain Refined Biological Optimization for the Treatment of Locally Advanced Nasopharyngeal Carcinoma

It has been believed that the better optimization can be achieved by the P++ optimization strategy since the P+ curve shows a rather shallow maximum. In this paper, the P++ optimization strategy has been verified by evaluating IMRT plans for a T4 stage NPC patient in the situation where difficult compromise has to be made between probabilities for tumor control and normal tissue injury. The results showed that including the biological objective gEUD into the plan optimization could decrease the mean dose of OAR. Theoretically, P++ optimization strategy could be helpful to find the refined optimization solution for radiation therapy planning. However, in clinical radiotherapy practice, disease situations will form restrictions to use the biological evaluation only. More factors including both physical and biological models should be considered in a planning evaluation process to achieve a best clinical solution.