Table 6.
Statistically significant Spearman's rank correlation coefficients of the differences in dose–volumetric parameters between treatment plan and delivery to Sl–h and Al–h of head and neck volumetric modulated arc therapy plans
| Dose–volumetric parameter | S0–0.4 | S0.4–0.8 | S0.8–1.2 | S1.2–1.6 | S1.6–2.0 | Mean speed | A0–4 | A4–8 | A16–20 | Mean acceleration | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Target 1 | |||||||||||
| D95% | rs | – | – | 0.677 | 0.464 | – | – | – | – | – | 0.464 |
| p-value | – | – | 0.001 | 0.039 | – | – | – | – | – | 0.039 | |
| D5% | rs | – | – | 0.648 | 0.541 | – | – | – | – | – | 0.462 |
| p-value | – | – | 0.002 | 0.014 | – | – | – | – | – | 0.040 | |
| Mean | rs | – | – | 0.675 | 0.616 | – | – | – | – | – | 0.495 |
| p-value | – | – | 0.001 | 0.004 | – | – | – | – | – | 0.026 | |
| Target 2 | |||||||||||
| D95% | rs | – | – | 0.467 | 0.451 | – | – | – | – | – | 0.480 |
| p-value | – | – | 0.038 | 0.046 | – | – | – | – | – | 0.032 | |
| D5% | rs | – | – | 0.702 | 0.552 | – | – | −0.529 | 0.531 | – | 0.675 |
| p-value | – | – | 0.001 | 0.013 | – | – | 0.018 | 0.017 | – | 0.001 | |
| Mean | rs | – | – | 0.647 | 0.670 | – | – | −0.461 | 0.465 | – | 0.623 |
| p-value | – | – | 0.002 | 0.001 | – | – | 0.041 | 0.039 | – | 0.003 | |
| Target 3 | |||||||||||
| D95% | rs | – | – | 0.519 | 0.515 | – | – | – | – | 0.481 | 0.563 |
| p-value | – | – | 0.023 | 0.024 | – | – | – | – | 0.037 | 0.012 | |
| D5% | rs | – | – | 0.674 | 0.597 | – | – | −0.476 | 0.473 | – | 0.552 |
| p-value | – | – | 0.002 | 0.007 | – | – | 0.039 | 0.041 | – | 0.014 | |
| Min. | rs | −0.569 | – | 0.651 | 0.579 | 0.628 | 0.586 | −0.577 | 0.630 | – | 0.694 |
| p-value | 0.011 | – | 0.003 | 0.009 | 0.004 | 0.008 | 0.010 | 0.004 | – | 0.001 | |
| Max. | rs | – | – | 0.579 | 0.747 | – | – | −0.543 | 0.574 | – | 0.546 |
| p-value | – | – | 0.009 | <0.001 | – | – | 0.016 | 0.010 | – | 0.016 | |
| Mean | rs | – | −0.540 | 0.541 | 0.569 | – | – | – | – | ||
| p-value | – | 0.017 | 0.017 | 0.011 | – | – | – | – | |||
| Organs at risk | |||||||||||
| Brain stem max. | rs | – | – | – | – | – | – | – | – | – | 0.467 |
| p-value | – | – | – | – | – | – | – | – | – | 0.038 | |
| Left parotid gland mean | rs | −0.484 | – | – | – | – | 0.478 | – | – | – | – |
| p-value | 0.031 | – | – | – | – | 0.033 | – | – | – | – | |
| Left optic nerve max. | rs | – | – | – | – | – | – | – | – | −0.480 | – |
| p-value | – | – | – | – | – | – | – | – | 0.032 | – | |
Al–h, the proportion of number of CPs of MLC accelerations ranging from l to h cm s−2; CP, control point; Dn%, dose received by n% of volume of structure; Max., maximum dose; Mean, mean dose; Min., minimum dose; rs, Spearman's rho; Sl–h, the proportion of number of CPs with MLC speeds ranging from l to h cm s−2.