"I don't have a life. I have a program." - The Doctor
The Emergency Medical Holographic Program is designed to temporarily suppliment the regular medical staff in the event that they are overloaded or incapacitated.
The Doctor's program was developed on Jupiter Station under the direction of Dr. Lewis Zimmerman, who the doctor's image is modeled after. Lt. Reginald Barclay also assisted with the Doctor's programming. The Doctor's database contains information from over 2000 medical reference sources, and the experience of 47 medical officers. The program is adaptive, allowing new modules to be added. Being a hologram, the doctor cannot leave the sickbay, and his program can not be transferred off the ship. Untill the ship was transpoted back in time, the Doctor then received a holographic emitter that's mobile by one of the villians they over came, what a surpirse!!!
"Heroes and Demons" - The Doctor ventures into the holodeck to rescue three trapped crew members.
"Projections" - Believing the ship has suffered a massive attack, the Doctor ventures from sickbay via a remote holo-projection system.
"Lifesigns" - The Doctor feels romantic for the first time while treating a Vidiian female for the Phage.