1National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan 030051, China 2Key Laboratory of Instrument Science & Dynamic Measurement Technology, North University of China, Taiyuan 030051, China 3Electronic Engineering Department, Taiyuan Institute of Technology, Taiyuan 030008, China 4Laboratory of Image Science and Technology, Southeast University, Nanjing 210096, China
Abstract：In optimization methods of conformal intensity modulated radiation therapy, the performance of biological optimization based on generalized equivalent uniform dose (gEUD) still requires improvement to control the target dose coverage precisely, while physical optimization based on dose volume does not reflect the nonlinear response of tissue to dose. Hence, a hybrid criteria optimization method integrating the biological criteria (generalized equivalent uniform dose: gEUD) and physical criteria (minimum dose, mean dose) was proposed in this paper. The new algorithm,taking full advantages of these two kinds of criteria, gave consideration to both the dose coverage of the target area and the protection of the organ.Its feasibility was tested on ten prostate cases through evaluation and comparison from the perspective of dosimetry and biology. Compared with physical criteria optimization, the hybrid criteria optimization reduced dose to the organs at risk on the premise that dose coverage characteristics of target were similar, and at the significance level of 0.05, the mean dose for rectum, V50 and V60 of rectum, the mean dose for bladder, V65,V70,V75,NTCP and gEUD of bladder were significantly different (P<0.05). Moreover, compared with gEUD based biological optimization, on the one hand the target dose coverage characteristics have been greatly improved with dose statistics, and the biological indicators were significantly different (P<0.05); on the other hand, organs at risk got better protection with significant difference (P<0.05) in rectal average dose, V50, V60, V75, NTCP and gEUD as well as in bladder V75 and gEUD. In conclusion, gEUD-based hybrid criteria optimization could reduce the dose to OAR that may be helpful to further improve the dose coverage of PTV and to increase the gain ratio of radio therapy while guarantying the dose to PTV.
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