A catheter assembly is disclosed according to one embodiment of the invention. The assembly includes a catheter body, a housing and a detector. The catheter includes a distal tip, a proximal end, and a fiber optic extending between the proximal end and the distal tip. The housing may include a channel adapted to support at least a portion of the distal tip of the catheter. The may be detector disposed within the housing so as to be spaced a fixed distance from the distal tip of the catheter. Methods for providing and calibrating a catheter supported within housing are also disclosed according to other embodiments of the invention.