Radiation Emission is an "anchor-debuff" set. With that in mind, you may want to create a bind or otherwise be ready to tell your team which target(s) you are using as said anchors, so they know which other enemies to target or where they should be fighting, in order to maximize their effectiveness. As a defender, you receive the greatest benefit from the buff/debuff effects of your powers, which includes the rad blasts. Especially while running higher difficulty content, those -DEF effects can really help your team's attacks to land more often. That being said, since it is very difficult to keep accelerate metabolism permanent, you'll want to make sure you either have some of the unique IOs that grant you extra endurance/recovery and/or make sure to pace yourself so you aren't constantly bottoming out your end bar. That being said, since you get the most benefit out of the leadership powers, maneuvers, tactics, and victory rush can help your team and address your end issues when AM is still recharging...