Scanner Development Early scanner -1972 4 minutes for 180 rotation 8 or 13 mm slices time for scan >30 mins 2 slices simultaneously UKRC: 22d May 2001
Scanner Development 301,1A Early scanner 1972 early images taken away overnight for processing 80 x 80 matrix UKRC: 22d May 2001
Then and now c) d) Kalender, Computed Tomography
传统的Ⅹ射线装置的缺点 ■影像重叠。深度方向上的信息至叠在起 引起混崤。 ■密度分辨率低,对软组织分辨能力低。 ■所用剂量大
传统的X射线装置的缺点 ◼ 影像重叠。深度方向上的信息至叠在 起， 引起混淆。 ◼ 密度分辨率低，对软组织分辨能力低。 ◼ 所用剂量大
X-ray Film/Screen Cassette X-rays Film- Silver halide grains-tums black when exposed PncosensimvelEmusion to visible light- relatively insensitive to x-rays-1% Phosphor emits visible and UV light Airtight cassette Screens can increase sensitivity by a factor of 100 Screens decrease resolution