Abstract: Embodiments of the disclosure may be drawn to brachytherapy applicators. Exemplary applicators may include an interstitial tube having a body with a proximal end and a distal end and a central conduit extending from the distal end of the body, wherein the central conduit includes a proximal opening, a distal opening, and a channel extending from the proximal opening to the distal opening, and wherein the proximal opening is offset from an axis of the body. The proximal opening may be configured to fluidly connect to a brachytherapy guide tube, and the channel of the central conduit may be dimensioned to receive at least one of a needle or a catheter therethrough.