Program Information
NTCP Modeling of Radiation Induced Temporal Lobe Injury in Nasopharyngeal Carcinoma Patients
H Deng1*, S Liu2 , X Wan2 , (1) Banner - University Medical Center Phoenix, Phoenix, AZ, (2) the Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong
Presentations
WE-RAM3-GePD-TT-4 (Wednesday, August 2, 2017) 10:30 AM - 11:00 AM Room: Therapy ePoster Theater
Purpose: To investigate the best NTCP model for radiation induced temporal lobe injury which is relative common in nasopharyngeal carcinoma patients after radiotherapy.
Methods: The left and right temporal lobes of nasopharyngeal carcinoma patients who received radiotherapy were contoured and their DVHs exported. In total 702 DVH files were obtained. Together with the binary data of the complication of radiation induced temporal lobe injury, several NTCP models were calculated. The models include serial reconstruction unit (SRU) model, Logit-EUD, Poisson-EUD, LKB-EUD, mean dose logistic regression model and cutoff dose logistic regression model. The Log Likelihood (LL) and Akaike information criterion (AIC value) were calculated for fitting quality assessment and comparison.
Results: The fitting parameters for our NTCP models are as follows: Logit EUD model, D₅₀=80Gy, k=28, 1/a=0 (i.e. serial model), LL=-83.16, AIC=172.32; Poisson EUD model, a=20 (i.e. close to serial), D₅₀=65Gy, LL=-93.56, AIC=191.12; Mean dose model, β₀=-6.13, β₁=0.168, LL=-106.44, AIC=216.87; Cutoff dose model, Dc=82Gy, β₀=-3.13, β₁=0.1850, LL=-139.06, AIC=284.12; SRU model with physical dose, σ=0.22, D₀=64Gy, LL= -91.3, AIC=186.6 and SRU model with biological dose, σ=0.17, D₀=67Gy, LL=-91.36, AIC=186.72; Lyman EUD model, n=0, m=0.07, TD₅₀=81Gy, LL=-82.84, AIC=171.68.
Conclusion: Our modeling indicates that temporal lobe acts like a serial organ, implying that the maximum dose to the organ is a useful predictor for toxicity. Based on AIC value, Lyman EUD, Logit EUD are of the best fitting quality, followed by SRU and Poisson EUD models, and all their parameters point to serial organ nature of the temporal lobe. The mean dose and cutoff dose models are the worst fitting models.
Contact Email: