It was in the prototype stages in 2368, when Dr. Russell brought it to the USS Enterprise-D in hopes of using it to treat a paralyzed Lieutenant Worf. At that point, it had very low success rate of 37% during holographic simulations. Starfleet Medical had three times turned down Russell's request to test it on a humanoid patient, and Dr. Crusher agreed that there was still too little data to risk its use.