Bio-Rad Personal Molecular Imager™ (PMI™) System - Manual (Page 19)

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When screens are not in use, they should be placed in the original shipping box provided
and placed in a dry and dark environment.
Caution: The phosphor surface of the screen is sensitive to damage from moisture,
mishandling and improper use of solvents. For detailed instructions on how to maintain the
K-type imaging screens, please refer to the Care and Maintenance section of this manual
(Section 5.2).
4.2.2 How to Erase Imaging Screens
The screen eraser (Figure 4.3) contains a series of bulbs that produce light that is a specific
wavelength range. When illuminated with this light, the phosphor crystals in the screen
discharge, returning to ground state. As a result, any screen background or residual signal
is removed.
Fig. 4.3. Screen eraser.
To erase the imaging screens, place the imaging screen against the front panel of the
Eraser-K with the white phosphor side facing the white diffuser plate of the unit. Set the
timer to the desired setting or to erase continuously set the timer to the HOLD position.
The erasure process typically requires only 10 minutes, assuming the previous sample has
not charged the phosphor in the screen above 20,000 pixel density units. An erasing time
guideline is shown in Table 4.1.
Note: The screen will not be damaged by extended erasure.
Note: Erasing the screen to the basal level is critical, since this has a direct effect on the
sensitivity, linear response, quantitation, exposure time, and image quality.
Erasure Guidelines
Table 4.1 Recommended Erasure Times
4.2.3 How to Prepare Samples
The recommended phosphor screen exposure time can be estimated, based on one-tenth
of the time it would normally take to visualize the sample on X-ray film.
Condition Background
(PD units)
Time
Before each exposure 1-20,000 10 minutes
After high dosage exposure >20,000 20 minutes
!