US Patent 4,058,910
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
A housing is provided with an observation opening which exposes a three dimensional model of an arterial system. When a rear-lighted projection screen is placed over the observation opening, light from a projector within the housing casts a shadow of the model on the screen to simulate the view seen in arteriography procedures.
Funk, David C. Apparatus for teaching the structures and projection of arterial systems. US Patent 4,058,910 filed November 18, 1976 and issued November 22, 1977. https://ir.uiowa.edu/patents/11