A needleless injection system is provided to deliver therapeutic fluids to aninternal treatment site in a patient,where the system is pressurized and is capable of compensating for differencesin injection media viscosity and mechanical systemcharacteristics. In one aspect, a needleless therapeutic fluid injectionsystem is provided that includes modular, interchangeablecomponents. In particular, the system includes a console that generallyincludes the electronic and/or hydraulic controlcompo-nents for the system, an injection chamber, and a shaft or cathetertube.
