Table 1.
Average GTV, CTV, PTV changes and differences on initial and adaptive CT scans
| Target volume (mL) |
ΔTV (mL) | ΔTV (%) | p-value | ||
|---|---|---|---|---|---|
| Initial | Adapted | ||||
| GTV | 45.032 ± 27.56 (-4.2 to -111.1) | 38.225 ± 26.30 (-1.8 to -111.5) | 6.80 ± 9.63 (-0.68 to -28.30) | 18.34 ± 23.01 (-1.30 to -60.00) | 0.003 |
| CTV | 122.27 ± 59.50 (-36.3 to -278.5) | 107.29 ± 55.17 (-32.6 to -287.4) | 14.98 ± 23.90 (-1.20 to -78.10) | 11.02 ± 20.12 (-0.75 to 53.06) | 0.004 |
| PTV | 153.08 ± 68.50 (-48.0 to -327.5) | 133.62 ± 64.32 (-43.4 to -338.3) | 19.40 ± 25.60 (0.04 to -84.90) | 12.30 ± 16.60 (0 to -35.90) | 0.001 |
Values are presented as mean ± standard deviation (min to max).
(-) values were indicative of target volume shrinkage on adaptive scan while (+) values were suggestive of target volume expansion.
GTV, gross tumor volume; CTV, clinical target volume; PTV, planning target volume; ΔTV, differences were calculated using GTVadapt – GTVInit, CTVadapt – CTVInit, and PTVadapt – PTVInit.