As shown in tables 4 and 5, it was found that less than 20% of the PTV70 received more than 110% of the prescribed dose in all the BBTP plans generated in the current study. These results at least did not violate the protocol designed by the Radiation Therapy Oncology Group of the American College of Radiology. Comparing with dose/dose volume based optimization, biological optimization was simpler and more effective. Based on our usual clinical practice using dose/dose volume based optimization, a large number of virtual organs were required for avoidance to reduce the dose outside the PTVs and contoured as hot and cold areas to improve target dose homogeneity. It is common to repeat the optimization cycles more than 5 to 6 times for adjusting the dose distributions through the trial and error approach. When using the biological optimization, the only virtual organ used was the normal tissue as listed in table 3. All the objective functions and physical constraints used were those listed in table 3. The total number of parameters used and the number of optimization cycles required were smaller than half of those used in dose/dose volume based optimization. The use of Eclipse biological related model for IMRT optimization in NPC produced INCB18424 comparable target coverage, target conformity and improved sparing of parotid glands with lower NTCP values when compared to physical dose based optimization operating on the same platform. For the primary target, BBTP plans produced comparable TCP values for early stage NPC cases and improved TCP values for advanced stage NPC cases compared to DVTP plans. The doses to serial organs and their corresponding NTCP values were comparable between the two approaches. The BBTP plans produced inferior target dose homogeneity with occurrence of mainly hot spots rather than cold spots. The hot spots were mainly located within the primary target volume with maximum doses of about 110%. This might be considered as clinically acceptable depending on the local practice of individual centers and the location of the hot spots. The use of biological based optimization combined with physical constraints can be a potential alternative to the conventional dose/dose volume based optimization for NPC cases. However, hot spots are sometimes considered as undesirable in NPC especially when they are located close to the skull base. There is still room for further improvement in the current BBTP approach in terms of improving target dose homogeneity. During the last years, remarkable efforts have been focused on understanding the molecular mechanisms underlying host–pathogen interactions in plant diseases. Among plant pathogens, Phytophthora species are eliciting a growing interest for their considerable economical and environmental impact. These filamentous microorganisms are oomycetes, belonging to the Stramenopiles, that include many devastating pathogens causing severe plant diseases.