Screen Film Radiology

4. Intensifying Screen Function and Geometry
v Modulation Transfer Function
(MTF) describes the resolution
properties of an imaging
system
v The MTF illustrates the
fraction (or %) of an object’s
contrast that is recorded by the
imaging system as a function of
object size (spatial frequency)
v F (linepairs or cycles/mm)
F=1/2∆, ∆ = object size
v As screen thickness ↑ MTF ↓
c.f. Bushberg, et al. The Essential Physics of
Medical Imaging, 2 nd ed., p 152.
4. Intensifying Screen Function and Geometry
v Crossover or print-through:
light from top screen
penetrates the film base and
exposes the bottom emulsion
or vice versa
v Due to type of film grain, not a
problem now
c.f. http://www.sprawls.org/resources/RADDETAIL/classroom.htm
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