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. 2013 Jan 30;8:23. doi: 10.1186/1748-717X-8-23

Table 2.

Quantitative parameters measuring quality: definition of indices

Parameter [ref] Definition Optimal Value Acceptable Minor Violation Major Violation
RTOG Conformity Index (CI) [11]
 Vpi/ VT
 1.0
 1.0 – 2.0
 ≥ 0.9-1.0 or > 2.0-2.5
 < 0.9 or >2.5
Target Coverage (TC) [12]
 VT,pi/ VT
 1.0
 ≥0.95 – 1.0
 0.90 - 0.95
 < 0.90
Homogeneity Index (HI)* [13] (D2%- D98%) / D50% 0.0 0.0 - 0.12 0.12 - 0.2 > 0.2

*HI minor and major deviations defined according to protocol deviation parameters for dose conformity and PTV D2%.

Abbreviations: Vpi, Prescription Isodose Volume; VT, Volume Target; VT,pi, 95% isodose volume within the target; D2%, D50%, D98%, Dose received by 2, 50 and 98 percent of the PTV, respectively.