Operation Manual
VacuDAP 2002
2002BA01e.DOC / 22.07.2004
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of
22
3 Operating
instructions
3.1 General
The VacuDAP 2002
measuring
system is used for measuring the dose area product
(DAP), which is a
direct measure of the radiation a patient is exposed to.
The measuring chamber is inserted in the collimator; it does not affect routine operation in any way.
As compared with measuring the incident radiation dose, the measurement of the dose area product
allows the influencing variables, dose rate, irradiation time and field size used to be determined. The
system measures the entire radiation received by the ionization chamber and accumulated within a
time which is started by pressing
Reset
.
3.2 Components and measuring principle
Fig. 1: Components of the VacuDAP 2002 measuring system
Within the ionization chamber (1), the X-rays produce charge carriers which are proportional to the
product of dose and X-rayed ionization chamber area. The small measuring currents so generated are
amplified and digitised by the detector electronics (2). The digital measuring signal is transmitted to
the display unit (3) where it is further processed and displayed.
3.2.1 Ionization chamber and detector electronics
The compact design of ionization chamber and detector electronics allow the installation inside the
collimator of the X-ray unit.The transparent ionization chambers are intended for use on X-ray
equipment with light beam diaphragm.
The electronic components include, among others, the chamber voltage generator, a charge amplifier
and a microprocessor. A signal cable is used for transmitting the measuring signal to the display unit.
