The invention discloses a Light Irradiating Unit (LIU) for providing radiant energy safely to a treatment site within the human body during treatment sessions. the LIU is comprised of the following modules: an Irradiating Array (IA) comprising LEDs longitudinally disposed in a single row along a flexible support member an external LED Controller and Power Supply (CPS) an Array Housing Catheter (AHC) for enclosing and guiding said IA to the treatment site and a Cooling Catheter (CC) for enclosing and cooling the AHC during treatment sessions the CC connects to a standard intra venous bag, containing cooling fluid, the is bag adapted to provide gravity induced cooling fluid flow through the CC during treatment sessions the CC further adapted to provide drainage of the cooling fluid during said treatment sessions.
