Various sealing structures are used in a front-loading
injector, for preventing leakage of spilled fluid from an external surface of a
syringe into the vicinity of the drive ram. For example, a sealing
gasket may be incorporated into the front face of the
injector housing, for
mating to the rearward circular edge of the cylindrical body of a
syringe. Alternatively, sealing and locking functions may be performed by a single structure on the rearward end of the
syringe. Further, leakage may be prevented by including a non-planar sealing
flange on the syringe, positioned on the syringe forward of the locking structure, or by a two-piece structure, including a syringe and a separate leakage stopping
washer for surrounding the syringe to halt the flow of fluid along the exterior of the syringe. As part of this aspect, or as an independent feature, the syringe may include an annularly discontinuous
flange forward of the locking structure, for providing mechanical support for the syringe against the
injector. Alternatively, an iris-like structure may be incorporated into the front surface of the injector, for closing about the syringe upon
insertion of the syringe into the injector.