Image therapy was a medical procedure used on Earth in the 20th century. It was often evaluated against other methods of treatment, among them chemotherapy. Doctor Leonard McCoy, traveling back in time to 1986 once heard two 20th century doctors discussing the pros and cons of image therapy versus chemotherapy, to which McCoy remarked that it was "unbelievable" patients had to endure such treatment. When asked if he had a different view, McCoy's response was "Sounds like the goddamn Spanish Inquisition if you ask me!" (Star Trek IV: The Voyage Home)