A catheter assembly, comprising: a core wire configured for linear actuation including extension and retraction, wherein: a proximal end of the core wire includes a sonic connector configured to couple to an ultrasound-producing mechanism for imparting vibrational energy to the core wire, and a distal end of the core wire is configured to modify intravascular lesions with vibrational energy; and a damping mechanism around a proximal-end portion of the core wire configured to dampen transverse wave-producing vibrational energy in the proximal-end portion of the core wire, the damping mechanism including: a gasket system configured to exert a compressive force around the core wire; and a retainer to retain the gasket system in a damping-mechanism bore of the catheter assembly, wherein the compressive force is sufficient to dampen transverse wave-producing vibrational energy in the proximal-end portion of the core wire without restricting the extension or retraction of the core wire through the damping mechanism, and a linear actuation mechanism configured to: extend the core wire from a fully retracted state of the core wire, and retract the core wire from a fully extended state of the core wire, wherein: the distal end of the core wire and a working length of the core wire up to 20 cm from a distal end of a sheath around the core wire are exposed in the fully extended state, and the working length of the core wire up to at least the distal end of the core wire are concealed in the sheath in the fully retracted state. a core wire configured for linear actuation including extension and retraction, wherein: a proximal end of the core wire includes a sonic connector configured to couple to an ultrasound-producing mechanism for imparting vibrational energy to the core wire, and a distal end of the core wire is configured to modify intravascular lesions with vibrational energy; and a proximal end of the core wire includes a sonic connector configured to couple to an ultrasound-producing mechanism for imparting vibrational energy to the core wire, and a distal end of the core wire is configured to modify intravascular lesions with vibrational energy; and a damping mechanism around a proximal-end portion of the core wire configured to dampen transverse wave-producing vibrational energy in the proximal-end portion of the core wire, the damping mechanism including: a gasket system configured to exert a compressive force around the core wire; and a retainer to retain the gasket system in a damping-mechanism bore of the catheter assembly, wherein the compressive force is sufficient to dampen transverse wave-producing vibrational energy in the proximal-end portion of the core wire without restricting the extension or retraction of the core wire through the damping mechanism, and a gasket system configured to exert a compressive force around the core wire; and a retainer to retain the gasket system in a damping-mechanism bore of the catheter assembly, wherein the compressive force is sufficient to dampen transverse wave-producing vibrational energy in the proximal-end portion of the core wire without restricting the extension or retraction of the core wire through the damping mechanism, and a linear actuation mechanism configured to: extend the core wire from a fully retracted state of the core wire, and retract the core wire from a fully extended state of the core wire, wherein: the distal end of the core wire and a working length of the core wire up to 20 cm from a distal end of a sheath around the core wire are exposed in the fully extended state, and the working length of the core wire up to at least the distal end of the core wire are concealed in the sheath in the fully retracted state. extend the core wire from a fully retracted state of the core wire, and retract the core wire from a fully extended state of the core wire, wherein: the distal end of the core wire and a working length of the core wire up to 20 cm from a distal end of a sheath around the core wire are exposed in the fully extended state, and the working length of the core wire up to at least the distal end of the core wire are concealed in the sheath in the fully retracted state. the distal end of the core wire and a working length of the core wire up to 20 cm from a distal end of a sheath around the core wire are exposed in the fully extended state, and the working length of the core wire up to at least the distal end of the core wire are concealed in the sheath in the fully retracted state.