The procedure required the patient to be completely motionless in an isotropic restraint to allow for the organ to always be in the correct location to operate properly. The holographic organ was then created through file records on the computer and projected into the patient.
This method was used as a holographic lung replacement for Neelix. When Neelix's lungs were removed by a Vidiian. The Doctor's idea worked, but Neelix was confined to an isotropic restraint. The Doctor was later able to transplant one of Kes' lungs into Neelix with help from the Vidiians. (VOY: "Phage")