A prostate treatment device (500) is described. The device comprises: an introducer shaft (510, 512) that is sized and configured for transurethral access into a patient； a vapor generator (570) that is configured to generate a condensable vapor； a vapor delivery needle (540) that is in communication with the vapor generator and slidably disposed within the introducer shaft； and a magnetic actuator (600A, 600B, 602A, 602B, 610, 612). The magnetic actuator is configured to apply magnetic force to the vapor delivery needle to move the vapor delivery needle between a retracted position inside the introducer shaft and an extended position at least partially outside of the introducer shaft and to axially move the vapor delivery needle toward the extended position from the retracted position at a velocity ranging from 0.1 meter per second to 20.0 meters per second.
