A system to be used to treat Leukemia, comprises a device to power, control and monitor an ultraviolet radiation as well as to monitor a blood contactless conductivity； and a catheter assembly with an inner dialysis catheter, an ultraviolet radiation source and a differential coil sensor. The system is using wavelengths of ultraviolet radiation to destroy infectious microbes that are in the blood and that are inside circulating tumor cells directly and indirectly as well as to destroy infectious microbes at primary tumor location (bone marrow). This is done without withdrawing the blood out of the body. Furthermore, the system measures a blood conductivity to evaluate the treatment process in a real time during the operation.
