Intensifying screens

1. These utilize phosphor which works to convert xray photon energy into light.

2. Used to use calcium tungstate until 1973 when efficiency of rare earth material was discovered.

3. Screen phosphors should have:

1. high atomic number

2. minimal afterglow

3. high conversion rate

4. Rare earth materials used:

• Gladolinium
• Lanthanum
• Yttrium

5. Light is isotropically produced. (Light traveling away from screen is reversed towards screen)

6. The base of an intensifying screen provides mechanical support for the phosphor layer.

7. Intensifying screens provide approximately 95% of films exposure.

8. All rare earth materials have lower atomic numbers than tungsten.

9. KvP values for screens should be greater than 60.

Category: Radiology Notes