We are investigating the performance capabilities of a niobium superco
nducting radiofrequency quadrupole (RFQ) accelerator for high-field co
ntinuous-wave operation, to provide greater acceleration and stronger
focusing of low-velocity ion beams. We present an example of an RFQ to
produce radioisotopes for positron-emission tomography (PET), and we
report on the mechanical design aspects of a short, superconducting RF
Q four-vane prototype structure that will be tested at high fields dur
ing the coming year.