A detachment system for delivering embolic coils to a treatment site in a vasculature of a patient, comprising: an elongated, flexible tube formed from a shape memory material, and having a distal portion and a proximal portion, said tube defining an interior lumen extending through the tube between the distal portion and the proximal portion of the tube, the distal portion of the tube having a temporary shape having a first configuration with a first inner diameter and a permanent shape having a second configuration with a second inner diameter that is larger than said first inner diameter of said first configuration of said temporary shape; a headpiece having a distal portion and a proximal portion, said proximal portion of said headpiece being releasably mounted within said distal portion of said tube, said second inner diameter of said second configuration of said permanent shape of said tube being larger than an outer diameter of said headpiece; a therapeutic embolic coil having a distal end and a proximal end, said proximal end of said therapeutic embolic coil being fixedly attached to the distal portion of said headpiece, said proximal portion of the headpiece extending proximally of said proximal portion of the embolic coil; and a resistive heating element contained within the interior lumen of the distal portion of the tube, whereby said headpiece and said therapeutic embolic coil attached thereto are configured to be releasable from said distal portion of said tube by heating of said distal portion of the tube by said resistive heating element to cause said distal portion of the tube to change from said temporary shape having a reduced diameter configuration to said enlarged diameter configuration, characterized in that the resistive heating element is disposed longitudinally along and in immediate contact with the inner wall surface of the tubular wall of the distal portion of the tube, to provide direct, even heating of at least a substantial majority of the length of the distal portion of the tube when the resistive heating element is energized. an elongated, flexible tube formed from a shape memory material, and having a distal portion and a proximal portion, said tube defining an interior lumen extending through the tube between the distal portion and the proximal portion of the tube, the distal portion of the tube having a temporary shape having a first configuration with a first inner diameter and a permanent shape having a second configuration with a second inner diameter that is larger than said first inner diameter of said first configuration of said temporary shape; a headpiece having a distal portion and a proximal portion, said proximal portion of said headpiece being releasably mounted within said distal portion of said tube, said second inner diameter of said second configuration of said permanent shape of said tube being larger than an outer diameter of said headpiece; a therapeutic embolic coil having a distal end and a proximal end, said proximal end of said therapeutic embolic coil being fixedly attached to the distal portion of said headpiece, said proximal portion of the headpiece extending proximally of said proximal portion of the embolic coil; and a resistive heating element contained within the interior lumen of the distal portion of the tube, whereby said headpiece and said therapeutic embolic coil attached thereto are configured to be releasable from said distal portion of said tube by heating of said distal portion of the tube by said resistive heating element to cause said distal portion of the tube to change from said temporary shape having a reduced diameter configuration to said enlarged diameter configuration, characterized in that the resistive heating element is disposed longitudinally along and in immediate contact with the inner wall surface of the tubular wall of the distal portion of the tube, to provide direct, even heating of at least a substantial majority of the length of the distal portion of the tube when the resistive heating element is energized.