TABLE II.
Effects of systematic longitudinal source positioning errors on dose to the HR-CTV, and organs at risk for 45° azimuthal emission angle. Only the organ-at-risk D2cc values for which the D2cc tolerance was violated following the positioning errors were included. Organ-at-risk tolerance D2cc-values for sigmoid colon, rectum, and bladder were 75, 75, and 90 Gy3, none of which were violated when there is no positioning error.
| Patient | Longitudinal positioning error (mm) | HR-CTV D90 change (%) | Sigmoid colon D2cc (Gy3) | Rectum D2cc (Gy3) | Bladder D2cc (Gy3) |
|---|---|---|---|---|---|
| 1 | −1 | −2.15 | 76.18 | ||
| +1 | −2.07 | 93.26 | |||
| 2 | −1 | −6.31 | 97.89 | ||
| +1 | −6.17 | 98.24 | |||
| 3 | −1 | −3.54 | 75.89 | ||
| +1 | −3.4 | 75.97 | |||
| 4 | −1 | −15.67 | 78.71 | ||
| +1 | −5.18 | 102.24 | |||
| 5 | −1 | −6 | 75.62 | ||
| +1 | −4.96 | 105.8 |