Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of Graph Search.
Concept
Photostimulated luminescence
Summary
Photostimulated luminescence (PSL) is the release of stored energy within a phosphor by stimulation with visible light, to produce a luminescent signal. X-rays may induce such an energy storage. A plate based on this mechanism is called a photostimulable phosphor (PSP) plate and is one type of X-ray detector used in projectional radiography. Creating an image requires illuminating the plate twice: the first exposure, to the radiation of interest, "writes" the image, and a later, second illumination (typically by a visible-wavelength laser) "reads" the image. The device to read such a plate is known as a phosphorimager (occasionally spelled phosphoimager, perhaps reflecting its common application in molecular biology for detecting radiolabeled phosphorylated proteins and nucleic acids).
Projectional radiography using a photostimulable phosphor plate as an X-ray detector can be called "phosphor plate radiography" or "computed radiography" (not to be confused with computed tomography which uses computer processing to convert multiple projectional radiographies to a 3D image).
On photostimulable phosphor (PSP) plates, the phosphor layer is typically 0.1 to 0.3 mm thick. After the initial exposure by short-wavelength (typically, X-ray) electromagnetic radiation, excited electrons in the phosphor material remain 'trapped' in 'colour centres' ("F-centers") in the crystal lattice until stimulated by the second illumination. For example, Fuji's photostimulable phosphor is deposited on a flexible polyester film support with grain size about 5 micrometers, and is described as "barium fluorobromide containing a trace amount of bivalent europium as a luminescence center". Europium is a divalent cation that replaces barium to create a solid solution. When Eu2+ ions are struck by ionizing radiation, they lose an additional electron to become Eu3+ ions. These electrons enter the conduction band of the crystal and become trapped in the bromine ion empty lattice of the crystal, resulting in a metastable state that is higher in energy than the original condition.
Official source
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.