ICAN-II was a proposed crewed interplanetary spacecraft that used the antimatter-catalyzed micro-fission (ACMF) engine as its main form of propulsion.
The spacecraft was designed at Penn State University in the 1990s as a way to accomplish a crewed mission to Mars.
The proposed ACMF engine would require only 140 nanograms of antiprotons in conjunction with traditional fissionable fuel sources to allow a one-way transit time to Mars of 30 days.
This is a considerable improvement over many other forms of propulsion that can be used for interplanetary missions, due to the high thrust-to-weight ratio and specific impulse of nuclear fuels.
[1] The radiation from ICAN-II's ACMF engine would be intercepted by a 4-meter radius silicon carbide shell.