PURPOSE: Accurate calibration of radiobiological parameters is crucial to predicting radiation treatment response. Modeling differences may have a significant impact on calibrated parameters. In this study, we have integrated two existing models with kinetic differential equations to formulate a new @entity5 regression model for calibrating radiobiological parameters for individual @entity1 . METHODS: A system of differential equations that characterizes the birth-and-death process of @entity5 cells in radiation treatment was analytically solved. The solution of this system was used to construct an iterative model (Z-model). The model consists of three parameters: @entity5 doubling time Td, half-life of dying cells Tr and cell survival fraction SFD under dose D. The Jacobian determinant of this model was proposed as a constraint to optimize the three parameters for six @entity135 @entity1 . The derived parameters were compared with those generated from the two existing models, Chvetsov model (C-model) and @entity18282 model (L-model). The C-model and L-model were optimized with the parameter Td fixed. RESULTS: With the Jacobian-constrained Z-model, the mean of the optimized cell survival fractions is 0.43  0.08, and the half-life of dying cells averaged over the six @entity1 is 17.5  3.2 days. The parameters Tr and SFD optimized with the Z-model differ by 1.2% and 20.3% from those optimized with the Td-fixed C-model, and by 32.1% and 112.3% from those optimized with the Td-fixed L-model, respectively. CONCLUSION: The Z-model was analytically constructed from the cellpopulation differential equations to describe changes in the number of different @entity5 cells during the course of fractionated radiation treatment. The Jacobian constraints were proposed to optimize the three radiobiological parameters. The developed modeling and optimization methods may help develop high-quality treatment regimens for individual @entity1 .

TH-E-BRF-06: Kinetic Modeling of XXXX Response to Fractionated Radiotherapy.

@entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity1 :: ('9606', 'Species') :: ['patients'] @entity135 :: ('MESH:D006258', 'Disease') :: ['head and neck cancer'] @entity18282 :: ('10611', 'Gene') :: ['Lim']
@entity5 :: (MESH:D009369,Disease) :: ['Tumor']
