Digital: Lesson 6 - CCD/CMOS Image Capture Exam.

Digital: Lesson 6 - CCD/CMOS Image Capture Exam. 1. What is a Charge-Cou- pled Devices? 2. How does a Charged-Cou- pled Device work? 3. Structure of a CCD: 4. Function of a CCD: The oldest indirect conversion digital radiography system used to acquire a digital image X-ray photons interact with a scintillation material, and the signal is transmitted by lenses or fiber optics to the CCD. During the transmission process, the lenses reduce the size of the projected visible light image One or more small capacitors convert the light into an electrical charge. This charge is stored in a sequential pattern and released line by line. A CCD is made up of a photosensitive receptor and electronics embedded in a substrate material in a silicon chip Incident light from a scintillator strikes the detector, and electron-hole pairs are produced in the silicon. -The amount of electron-hole pairs is related to the amount of light absorbed. The electrons are held by electrostatic forces in the array until the charge is read out to form the image. 5. Image-Related Characteristics 6. Reducing the im- age size involves several compo- nents that con- tribute to the quality of the im- age: It is not currently practical to manufacture a CCD chip larger than 5 cm x 5 cm. -Most range from 2 to 4 cm -The image must be matched to the size of the CCD. -CCD technology uses lenses or fiberoptics so that the image matches the receptor size. -The scintillator -Light collection component -Noise 7. The Scintillator The two main types of phosphors are structured and unstructured (turbid). -CsI is considered structured because of its needle-like crystals. -Gd2O2 is considered unstructured because of its powder-like gr