X-ray sources abound around us. They include the following:
Natural X-ray sources:
Astrophysical X-ray source, as viewed in X-ray astronomy
X-ray background
Naturally occurring radionuclides
Artificial X-ray sources
Radiopharmaceuticals in radiopharmacology
Radioactive tracer
Brachytherapy
X-ray tube, a vacuum tube that produces X-rays when current flows through it
X-ray laser
X-ray generator, any of various devices using X-ray tubes, lasers, or radioisotopes
Synchrotron, which produces X-rays as synchrotron radiation
Cyclotron, which produces X-rays as cyclotron radiation