.. index:: 
   single: Parameters; 1D Flatness 9050

1D Flatness 9050
================

Returns the ratio of the length of the 90% isodose over the length of the 50% isodose, with the dose normalized at 100% at beam center.:

.. math:: 100 \cdot \cfrac {FW_{90\%}} {FW_{50\%}}

where (FW\ :sub:`90%`) and (FW\ :sub:`50%`) are the distances between the 90% and 50% isodose lines respectively.
   
**Protocol invocation name**: 1D Flatness 9050