A system comprising a coolant source, a delivery apparatus and a delivery device, the delivery apparatus comprising an optical element, the delivery device comprising: an elongate body having a coolant delivery lumen in fluid connection with the coolant source and being insertable into the delivery apparatus; and an ablation assembly positionable in an airway of a bronchial tree and being connected to a distal end of the elongate body, the ablation assembly including: an energy emitter assembly configured to output energy to ablate targeted tissue of the bronchial tree, the energy emitter assembly comprising a fluid delivery conduit in fluid connection with the coolant delivery lumen and one or more energy emitters coupled to the fluid delivery conduit; and a transparent or semi-transparent conformable balloon movable from a collapsed state to an expanded state to bring a tissue-contacting portion of the energy emitter assembly into contact with an airway wall of the bronchial tree, the balloon being configured to deploy the energy emitter in the expanded state and to contain and circulate a coolant delivered through the coolant delivery lumen and being movable into contact with a wall of the airway, wherein in the expanded state, the fluid delivery conduit at least partially wraps circumferentially around an exterior surface of the balloon, and the one or more energy emitters are configured to engage a wall of the airway in at least one intercartilagenous space extending between adjacent cartilaginous rings of the airway, and the surface of the balloon is configured for optical coupling with the optical element which is configured to be positioned in the airway outside of the balloon, the optical element facing the surface of the balloon such that a position of the one or more electrodes of the energy emitter assembly in the at least one intercartilagenous space is viewable through the surface of the balloon and the coolant contained therein with the optical element when the balloon is in the expanded state. an elongate body having a coolant delivery lumen in fluid connection with the coolant source and being insertable into the delivery apparatus; and an ablation assembly positionable in an airway of a bronchial tree and being connected to a distal end of the elongate body, the ablation assembly including: an energy emitter assembly configured to output energy to ablate targeted tissue of the bronchial tree, the energy emitter assembly comprising a fluid delivery conduit in fluid connection with the coolant delivery lumen and one or more energy emitters coupled to the fluid delivery conduit; and a transparent or semi-transparent conformable balloon movable from a collapsed state to an expanded state to bring a tissue-contacting portion of the energy emitter assembly into contact with an airway wall of the bronchial tree, the balloon being configured to deploy the energy emitter in the expanded state and to contain and circulate a coolant delivered through the coolant delivery lumen and being movable into contact with a wall of the airway, wherein in the expanded state, the fluid delivery conduit at least partially wraps circumferentially around an exterior surface of the balloon, and the one or more energy emitters are configured to engage a wall of the airway in at least one intercartilagenous space extending between adjacent cartilaginous rings of the airway, and a transparent or semi-transparent conformable balloon movable from a collapsed state to an expanded state to bring a tissue-contacting portion of the energy emitter assembly into contact with an airway wall of the bronchial tree, the balloon being configured to deploy the energy emitter in the expanded state and to contain and circulate a coolant delivered through the coolant delivery lumen and being movable into contact with a wall of the airway, wherein in the expanded state, the fluid delivery conduit at least partially wraps circumferentially around an exterior surface of the balloon, and the one or more energy emitters are configured to engage a wall of the airway in at least one intercartilagenous space extending between adjacent cartilaginous rings of the airway, and