BOS Controller described a ASDE-X alert activated when a Runway 9 departure traveled through the intersecting Runway 4R with landing traffic on short final; the reporter indicationg it was a false alert.

Narrative

Aircraft X was on a Visual Approach to Runway 4R. I cleared the twin Cessna for take off on Runway 9 which intersects Runway 4R. As the twin Cessna was accelerating through the Runway 4R intersection; the ASDE-X alerted to send the aircraft around because of the intersecting runway departure. The applied spacing for determining if there was enough room for the twin Cessna is the same that I have used countless times. In addition if the aircraft was too close for the Runway 9 departure the Runway Status Lights would have alerted the twin Cessna that the condition was not safe. The ASDE-X for some reason alerted in a situation that occurs on a regular basis; and had not previously alerted in identical situations. I was required to issue the aircraft a go-around while the aircraft was almost to the runway creating an unnecessary and unsafe condition for it. By the time I was able to say go-around the Runway 9 departure; the twin Cessna; was already through the intersection and there was no reason to issue a go-around. Recommendation; adjust the parameters of the ASDE-X; to eliminate the early and unnecessary alert of a go-around.