Table 5 Correlation coefficients (r) with corresponding p-values of Pearson’s or Spearman’s correlation test of dose-volumetric parameters of organ-at-risk volumes to modulation complexity score for volumetric modulated radiation therapy and total monitor units for cervical and thoracic spine stereotactic ablative radiotherapy plans

Spinal cord

ΔD_1.2 cc

-0.679

< 0.0001

0.793

< 0.0001

ΔD_0.35 cc

-0.504

0.007

0.644

< 0.001

ΔD_0.035 cc

-0.349

0.069

0.380

0.047

ΔMaximum dose

-0.394

0.039

0.584

0.001

ΔMean dose

-0.686

< 0.001

0.790

< 0.0001

Spinal cord PRV

ΔD_1.2 cc

-0.533

0.004

0.605

0.001

ΔD_0.35 cc

-0.287

0.138

0.460

0.015

ΔD_0.035 cc

-0.652

< 0.001

0.781

< 0.0001

ΔMaximum dose

-0.276

0.155

0.540

0.003

ΔMean dose

-0.635

< 0.001

0.804

< 0.0001

Ring_1.5 cm

ΔV_105% (cm³)

-0.075

0.704

0.216

0.269

ΔV_110% (cm³)

-0.004

0.983

0.133

0.499

ΔV_115% (cm³)

-0.089

0.652

0.137

0.487