A swallowable in vivo therapeutic device, and a method for use of a device. The device may include a transparent case and one or more radiation sources, the radiation sources to treat the detected pathological lesions inside the gastrointestinal (GI) tract with light during the passage of the device through the GI tract. A method may include inserting into a patient a device, rotating external magnets in close proximity to the patient, thereby fully controlling the movement of the device inside the GI tract, stopping the device and activating the light radiation in areas of the pathological lesions for a predetermined period of time, and deactivating the light radiation and moving the device further through the GI tract.
