TOP-X100NR USER MANUAL
Innomed Medical Inc.
17
6. Automatic exposure control (AEC)
6.1 The AEC operating mode
When using the AEC operating mode, the so-called ionization chamber placed
between the patient and the film performs the in time exposure stoppage. The
ionization chamber measures the dosage passing through it and stops exposure
when the dosage required for the optimal darkening of the used film is reached.
AEC can be used in both APR and manual mode, but only if AEC mode is configured
for the given examination device. In both cases the AEC function can be turned on or
off according to user preference. In APR mode, depending on body part related
programming the program starts either with or without AEC. The LEDs above the
AEC field buttons (25-27) indicate which fields are used. If any of the three LEDs are
on, the device is operating in AEC mode.
The AEC dominant field buttons (25-27) determine which part of the image is
considered important; while the DENSITY (density correction) buttons (12, 18) let
you set whether to make the image darker or lighter than usual.
In AEC mode the time (sec) or current-time product (mAs) parameters on the RAD
parameter displays (C, D) only indicate the maximum value the generator will allow
during exposure. If this exposure time value or the mAs value is reached during
exposure, the generator will turn off exposure. These are the so-called backup
values. These are protections in case the AEC function is not operational. This can
happen, for example, if X-ray radiation does not reach the ionization chamber,
because the collimator setting is not appropriate.
If the AEC function did not stop the exposure but reaching either the set time or the
set mAs value, the generator displays an error message at the end of the exposure,
warning that the film will most likely be too light. In this case the error message
remains and exposure is disabled until the user pushes any of the buttons on the
console to acknowledge it.
The two backup values have to be set according to the expected mAs value within
the current conditions (FFD, patient size, etc.) and at the given tube voltage (kV).
6.2 AEC operating mode setting possibilities
You can access AEC operating mode by selecting one or more of the AEC dominant
fields (25-27).
The LED over the selected field’s button turns on
and the DENSITY field appears on the LCD display (A). The mentioned field is not
accessible in other operating modes. Setting the dominant fields does not affect the
recording parameters.