The present invention is embodied in a medical device which is comprised of a thermal energy delivery component, for example, including an elongate optical fiber terminating in a lateral laser energy emitter, and an outer coolant component, which includes a cannula for receiving the thermal energy delivery component, which terminates in an energy-transmissive balloon for surrounding the thermal energy emitter and providing a tissue-contacting coolant chamber. The cannula portion of the coolant component is moveably sealed around the laser energy delivery component. In one embodiment, a retaining means prevents the thermal energy delivery component from being detached from the coolant component. In an alternate embodiment, there is no retaining means, allowing the more costly thermal energy delivery component to be removed, sterilized and later reused, whereas the less costly outer coolant component, which contacts tissue, blood and body liquids, can be discarded after use.