DDT was equal to 2 cGy for the local normalization analysis cases.

Dose difference threshold is defined as the minimum absolute dose error considered in the analysis when using local normalization.

In the case of local normalization method, the authors set three dose difference threshold (DDT) values of 2, 3, and 5 cGy.

With 3%∕3 mm gamma criteria, the overall passing rate with local normalization was 4.6% less on the average than with global one, as expected.