A new Impact Factor of 6.461 (previous 3.709) has been announced for the journal Frontiers in Public Health, that includes the specialty of “Radiation and Health“, Chief Editor Dariusz Leszczynski.
If interested, please, consider submission of your next manuscript.
BRHP - Between a Rock and a Hard Place 
It is used to measure the importance or rank of a journal by calculating the times its articles are cited. How Impact Factor is Calculated? The calculation is based on a two-year period and involves dividing the number of times articles were cited by the number of articles that are citable.
Could you explain what that means?