Variations in Rectal Volumes and Dosimetry Values Including NTCP due to Interfractional Variability When Administering 2D-Based IG-IMRT for Prostate Cancer
Table 4
Summary of NTCPs (%) for the rectum: predictions based on the initial plan and on-treatment CBCTs analyses.
Late rectal bleeding
Initial plan
CBCTs
Rectal grade ≥ 2 (RTOG) using LKB model
Mean ± SD
0.10 ± 0.06
1.12 ± 0.76
Median (range)
0.09 (0.02–0.24)
0.35 (0.01–6.16)
Rectal grade ≥ 2 (bleeding) using RS model
Mean ± SD
0.65 ± 0.30
2.29 ± 0.83
Median (range)
0.64 (0.15–1.22)
1.48 (0.18–7.66)
Combined grade ≥ 2 rectal toxicity (QUANTEC update) using LKB model
