“…Hence, non-multiplying detectors such as CCDs and photodiodes cannot work with such few radiation counts (assuming that there are 10 5 100 keV X-rays received by a single detector element in 1 s, 1 X-ray can produce 10 5 electron-hole pairs o1 eV per electron-hole4 the signal current of the detector element is 1.9 nA. The dark current of most photodiodes is several nanoamperes [15], and so it is difficult to distinguish signals from its background.). The backscattered X-ray detector would work in the counting mode when the X-ray rate is not very high.…”