Villa Sistemi Medicali ENDOS AC, User Manual

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USER'S MANUAL
Technical data
(Rev. 7) ENDOS AC/ACP - CE 25
By using a tube with grid it is possible to reduce to the minimum the
time required for the anodic current, and as a consequence, the dose
adjustment to reach the steady state, so there is very little difference
between the exposure time measurement using the invasive and the non
invasive method.
Corrective actions
A practical method can be applied to get round the problem which can
be described this way:
•
In a graph you report the values of times measured using the
equipment compared with the ones displayed by the timer
(automatically corrected for the line variations): the dots of the graph
are interpolated with a straight line (if possible by the least square
method or more simply in a graphic way).
•
You determine the intercept on the Y axis of this straight line: this
can be assumed as the time value that the non-invasive device adds
to each measurement due to the radiation which reaches the device
before the anodic current is 25% of its maximum value.
•
Then you subtract this "offset" time from all the device measurements
and you proceed with comparing the time measurements displayed
by the timer.