De or het dosisverlaging?

The correct Dutch article is:

de dosisverlaging

Rule Words ending in -ing: almost always de. See the rule

How to use dosisverlaging

the dosisverlagingde dosisverlaging
this dosisverlagingdeze dosisverlaging
that dosisverlagingdie dosisverlaging
our dosisverlagingonze dosisverlaging
your dosisverlagingjouw dosisverlaging
every dosisverlagingelke dosisverlaging
which dosisverlaging?welke dosisverlaging?
a big dosisverlaging / the big dosisverlagingeen grote dosisverlaging, de grote dosisverlaging