change output hash structure to key-based rather than array-based.
add preferred_unit_by_site for Prostate.
define unit of m3, which is not supported by ruby-units by default.
make method name in primary app more clearer.
add some standardize_site for GYN organs. use a method to get preferred unit, and if non-matched, return the original unit.
new constrants
if no site available, discard the item.
the carotid sonography SR need another parser.