A system for disinfecting an intravenous catheter and/or other fluidic tubing includes attaching a device around the catheter and delivering a high dose of ultraviolet or other type of radiation to the catheter connection point and adjacent tubing. The device may include a UV radiation source connected to a catheter attachment assembly via fiber optic cable, allowing transmission of UV radiation from the source to an internal reflector unit. The UV source may be built into the catheter connection assembly. The device may be a handheld device that fits over a catheter connection point, with single or multiple integrated UV sources to deliver 360 degree radiation around the catheter, with mirrors to increase light delivery. The method involves controlled exterior irradiation of a catheter connection point to disinfect the lumen via transmitted light through the catheter wall. Commercially available catheters or those specially designed for passage of radiation may be used.