Logos Imaging EPIX Scanner
User Manual
28
Recommendations on Lighting Conditions
for Erasing Imaging Plates
In order to completely erase imaging plates,
99.5% of the image information must be
removed. Scanning only removes part of the
information. To completely erase imaging
plates, follow the guidelines given below. It is
important that you measure the light intensity
with a light meter at the point where the
imaging plate will be positioned. The intensity
of light changes dramatically as you move
away from the source. Erasing the imaging
plates for periods of time longer than
suggested does not harm them. A good place
to store your imaging plates is under the
erasing light source.
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Fluorescent Lights
A light box typically gives off between
1000 and 5000 lux. Measure your light box
and use the lowest value to determine the
erasing time. At 1000 lux, an imaging plate
will be erased in 1 minute. At 2000 lux or
more, 30 seconds is sufficient.
œ
Incandescent Lighting
At 1000 lux, an imaging plate will be
erased in about 2 minutes. At 2000 lux or
more, erase for 1 minute.
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Sunlight
Full sunlight on a bright day can be as
strong as 70,000 lux. At this intensity, it
takes less than 10 seconds to erase imaging
plates. However, sunlight is too variable,
and we do not recommend using it.
If you are unable to directly measure the light
output from your erasing light source, or do
not have an erasing light source greater than
1000 lux, use the practical test, below, to
determine your erasing time.
Practical Test
1.
Completely erase an imaging plate by
subjecting it to direct, intense light for
about 20 minutes.
2.
Scan the imaging plate. No image should
appear on the monitor. If an image does
appear, repeat step 1 with a more intense
light source.
3.
Place the imaging plate in a sleeve or
cassette.
4.
Expose the imaging plate using normal
exposure conditions. If possible, place an
object, in the path of the x-ray beam.
5.
Turn on your erasing light source. We
recommend a light box or a minimum l00-
watt incandescent light bulb (see Section
5.2).
6.
Remove the imaging plate from its sleeve
or cassette and place it with the blue side
toward the light for 2 minutes.
7.
Scan the imaging plate. If an image
appears, the plate was not completely
erased. Repeat step 6, adding a minute to
the exposure time. Continue to repeat until
no image appears on the monitor. Record
the erasing time that resulted in no image.
This is the time required to erase an
unscanned imaging plate.
8.
Repeat steps 1-4. This time, under low
light conditions, remove the imaging plate
from the sleeve or cassette and mount it on
the carousel. Scan the imaging plate.
9.
Remove the scanned imaging plate and
place it, in the dark, into a light-protected
area (such as a light-tight drawer.
10.
Now repeat steps 6 and 7, exposing one
plate (blue side toward light) to the erasing
light for 2 minutes, the next plate for 3
minutes, etc., until you find the point
where no image appears on the monitor.
This is the time required to erase a scanned
imaging plate.
The time required to erase an imaging plate
will vary depending on the quality and
intensity of the erasing light source. It should
be fairly easy to find a light source that will
erase imaging plates in 2-3 minutes.
