PHYS1008 Lecture Notes - Lecture 5: Image Intensifier, Charge-Coupled Device, Caesium Iodide
Document Summary
Patient positioned on ct couch, driven through gantry while x-ray tube is energised (x-ray tube, detector array stationary), result in digital radiograph. X-ray beam is collimated to fan by prepatient collimators. Postpatient image forming x-rays are collimated to a fan that corresponds to the detector array a scintillation phosphot, usually nai or csi and is married to a linear arry of ccds through a fiberoptic light path. Principal advantageous imaging characteristics: sensitivity, dynamic range, size. Contrast in unrelated to image receptor x-ray exposure. Low x-ray exposure, response of ccd system is greater than screen film = lower patient dose during dr. Small = highly adaptable to dr (1~2cm), pixel size (100x100um) Receive light from area x-ray beam as it interacts with scintillation phosphor such as cesium iodide. Indirect dr process => x-rays are converted to light then electric signal. Use tiled ccds receiving light from a scintillator allow use of an area x-ray beam so that exposure time is short.
