Operation Manual
VacuDAP 2002
2002BA01e.DOC / 22.07.2004
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4 Preventive maintenance and checks/tests
4.1 General
Under normal operating conditions, the air-open ionization chamber and the display unit are not
subjected to any wear.
In the interest of a high measuring accuracy, the operational reliability and serviceability of the system
shall be checked within the framework of the X-ray equipment maintenance which is required to be
performed at certain intervals (RöV, X-ray Ordinance). During such checks, the patients' leakage
currents must be measured.
4.2 Stability test
Regularly, the stability of the entire system is automatically tested during the POWER-ON TEST.
When it is necessary, the test can be repeated in the MEASURE function phase by calling up the
TEST function (see 3.3.3,
TEST function
).
4.3 Checking the indicated values for drifting
A drift check of the indicated values can be made after the stabilization time (see 2.6,
Stabilization
time
) as follows:
1. Call up the RESET function (see 3.3.5,
RESET function
).
2. With typical X-ray equipment settings, direct a defined radiation on the measuring system.
3. Wait 3 seconds, then note down the indicated value.
4. Leave the measuring system in the MEASURE mode for a rest period of at least one hour,
without exposing it to radiation.
5. After this time, read the value a second time and compare it with the first value.
For every hour of the rest period, the second value may deviate from the first value by a maximum of
1 mGy*cm².
If the deviation is greater and cannot be reduced even after drying the ionization chamber at max.
50°C, have the measuring chamber checked by the manufacturer (see 5.2, After-sales s
ervice and
repairs
).
4.4 Overall calibration test
Before its delivery, the VacuDAP 2002 dose area product measuring system was calibrated in line
with IEC 60580 by means of a calibrated reference unit (IEC 61674); see 2.7,
Factory calibration
).
The overall calibration test of the measuring system should be made
every two years at the latest.
It is recommended to record all testing conditions, measured data and
calibration factors.
In checking the calibration of the measuring system, the dose area product is determined as the
numerical product of the cross-sectional area of the useful beam and the dose measured in the cross-
sectional plane (air kerma), with the variables measured successively at the same distance from the
focal spot. The dose area product so measured is compared with the indicated value on the
VacuDAP 2002.
