(Radio)Biological Optimization of External-Beam Radiotherapy

Figure 2

The distribution of NTCP values (grade 2 pneumonitis) estimated for a series of Clatterbridge NSCLC patients all with a 𝐷_presc of 55 Gy in 20 fractions; LKB model used with parameters 𝛼/𝛽=3; 𝑇𝐷₅₀=24.5 Gy; 𝑚=0.37, 𝑛=1 [35]. The extremely wide variation in NTCP is simply a reflection of the wide variation in tumour sizes, tumour position, and hence volume of lung in the radiation fields. Note that the average NTCP was 9.5% [36] (adapted from [38]).