X-rays were first discovered by Dr. W. Roentgen in Germany in 1895 and have currently been utilized in a wide range of fields including physics, industry, and medical diagnosis. Detectors for X-ray applications span a broad range including a-Si detectors, single crystal detectors, and compound detectors. There are many kinds of detectors made especially of Si single crystals. For X-ray detectors, Hamamatsu offers Si photodiodes, Si APDs, CCD area image sensors, and CMOS area image sensors, flat panel sensors, etc. Applications of our X-ray detectors include dental X-ray imaging and X-ray CT (computer tomography) in medical equipment fields, as well as non-destructive inspection of luggage, foods, and industrial products; physics experiments; and the like.

In the low energy X-ray region called the soft X-ray region from a few hundred eV to about 20 keV, direct detectors such as Si PIN photodiodes, Si APDs, and CCD area image sensors are utilized. These detectors provide high detection efficiency and high energy resolution, and so are used in X-ray analysis, X-ray astronomical observation, physics experiments, etc.

The hard X-ray region with energy higher than soft X-rays is utilized in industrial and medical equipment because of high penetration efficiency through objects. Scintillator detectors are widely used in these applications. These detectors use scintillators to convert X-rays into visible light and detect this visible light to detect X-rays indirectly.

Especially in the medical field, the digital X-ray method, which uses X-ray detectors with large photosensitive area, is becoming mainstream, replacing the conventional film-based method. In non-destructive inspection, dual energy imaging, which allows image capturing with deep tones by simultaneously detecting high- and low-energy X-rays, is becoming popular.