A phantom for use in quality control measurement of a fully integrated magnetic resonance/PET scanner is disclosed. The phantom features radiation activity distributed throughout an electrically conductive binder. Suitably, the binder is elastomeric and includes carbon fibers distributed throughout it to set the conductivity of the phantom to a desired level. The phantom is applicable to various multimodality integrated medical imaging systems such as MR/SPECT and MR/CT in addition to MR/PET.