X-ray imaging using a consumer-grade digital camera

Abstract

2 þ Computed radiography abstract The recent advancements in consumer-grade digital camera technology and the introduction of high- resolution, high sensitivity CsBr:Eu 2 þ storage phosphor imaging plates make possible a new cost- effective technique for X-ray imaging. The imaging plate is bathed with red stimulating light by high- intensity light-emitting diodes, and the photostimulated image is captured with a digital single-lens reflex (SLR) camera. A blue band-pass optical filter blocks the stimulating red light but transmits the blue photostimulated luminescence. Using a Canon D5 Mk II camera and an f1.4 wide-angle lens, the optical image of a 240 � 180 mm 2 Konica CsBr:Eu 2 þ imaging plate from a position 230 mm in front of the camera lens can be focussed so as to laterally fill the 35 � 23.3 mm 2 camera sensor, and recorded in 2808 � 1872 pixel elements, corresponding to an equivalent pixel size on the plate of 88 mm. The analogue-to-digital conversion from the camera electronics is 13 bits, but the dynamic range of the imaging system as a whole is limited in practice by noise to about 2.5 orders of magnitude. The modulation transfer function falls to 0.2 at a spatial frequency of 2.2 line pairs/mm. The limiting factor of the spatial resolution is light scattering in the plate rather than the camera optics. The limiting factors for signal-to-noise ratio are shot noise in the light, and dark noise in the CMOS sensor. Good quality images of high-contrast objects can be recorded with doses of approximately 1 mGy. The CsBr:Eu