Exam category: Image Production → Image Acquisition & Evaluation
Why it matters: This is how the exposure that leaves the patient actually becomes data — both the older plate-based system (CR) and the newer flat-panel systems (DR) are tested, along with the numbers that describe how well a receptor performs.
A digital receptor is an array of tiny detector elements, each recording how much radiation hit it. That array of values becomes the image's matrix; each individual value is a pixel. Two different receptor designs get from "x-ray hits the detector" to "electrical signal the computer can use" — one (CR) captures the image on a reusable plate that has to be scanned separately, the other (DR) reads out electronically in one step.
CR uses a cassette-housed imaging plate (IP) instead of a fixed detector. The IP's phosphor layer — a photostimulable phosphor (PSP), typically barium fluorohalide doped with europium — absorbs the exit radiation and stores the resulting energy as a latent image, trapped in the phosphor's electrons rather than displayed anywhere yet.
Reading the plate (two-step process):
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An exposed CR imaging plate goes into the reader. What turns its stored latent image into a light signal?
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