Room: ePoster Forums
Purpose: As the accuracy of radiotherapy techniques continues to increase,hypofractionation such as stereotactic radiotherapy (SBRT) are widely used. In predicting the therapeutic effects of SBRT and calculating the biological effect dose(BED),the linear quadratic (LQ) model now used will error estimate the therapeutic effect, and the higher the single dose, the greater the error.
Methods: With the increase of the fractional dose, the fitting accuracy of the LQ model in low-sensitivity cells is mainly the repair of the sublethal damage by the cells themselves. The reason for affecting the fitting accuracy of the LQ model in highly sensitive cells is the conversion of sublethal to lethal damage. We describe the repair and lethal transition by adding a correction function G(d) to the quadratic term of the LQ model.
Results: Seven kinds of cell survival data with survival information in high dose area were obtained from published literature. The cell survival data were divided into two groups according to their sensitivity.The improvement of the fitting accuracy of the improved model in the first group compared to the LQ model is mainly manifested in high dose areas, such as the Ï‡2/df value of the DU145 cell line, which is increased from 7.2 to 2.10(the smaller the Ï‡2/df value, the higher the accuracy of the fitting). The improvement of the fitting accuracy of the improved model in the second group compared to the LQ model is mainly manifested in the shoulder region, such as the Ï‡2/df value of the EMT6 cell line, which is increased from 8.32 to 0.11.
Conclusion: The improved LQ model can accurately describe the cell survival curve in the whole dose area, and can be used to calculate the biological effect dose and compare the biological response between different radiotherapy regimens.