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Table 3 Radiation dose tolerances for the SCM with respect to neck muscle spasm, as determined using ROC curve analysis

From: Patient- and treatment-related risk factors associated with neck muscle spasm in nasopharyngeal carcinoma patients after intensity-modulated radiotherapy

  Area under ROC curve Standard error P Lower limit Upper limit Cut-off point Sensitivity Specificity
V20a 0.795 0.030 <0.001 0.737 0.853 99.99% 0.920 0.673
V25 0.810 0.029 <0.001 0.752 0.867 99.99% 0.900 0.713
V30 0.815 0.029 <0.001 0.758 0.872 99.94% 0.900 0.709
V35 0.834 0.029 <0.001 0.777 0.892 98.94% 0.920 0.665
V40 0.834 0.029 <0.001 0.777 0.891 97.58% 0.920 0.685
V45 0.826 0.029 <0.001 0.769 0.883 94.72% 0.900 0.689
V50 0.860 0.025 <0.001 0.810 0.910 90.02% 0.900 0.732
V55 0.895 0.023 <0.001 0.849 0.941 65.78% 0.940 0.524
V60 0.934 0.024 <0.001 0.887 0.981 61.92% 0.900 0.953
V65 0.848 0.303 <0.001 0.784 0.912 28.94% 0.680 0.902
V70 0.675 0.046 <0.001 0.584 0.766 0.57% 0.600 0.744
  1. Abbreviations: SCM sternocleidomastoid muscle, ROC receiver operating characteristic, V20 a percentage of the sternocleidomastoid muscle volume that received >20 Gy; other dosimetric parameters are reported in a similar manner