Inżynier i Fizyk Medyczny 6/2016 vol. 5
321
artykuł
/
article
radioterapia
/
radiotherapy
was updated and fully tested by the user (acceptance
tests and commissioning). The update didn’t change the
facilities of the user and engineering logs. An idea of an
independent detector/control system was created be-
cause of:
––
the Flexitrion TDU control system doesn’t ensure
the user that treatment provided is as planned,
––
the Felxitron TDU control system provides records
off-line what causes lack of possibilities to compen-
sate the lost pulse or to stop treatment when the
additional pulse would happen,
––
the user logs and engineers logs don’t provide clear
information about the events and issues,
––
the engineers logs use coded system of description
of the events/issues, what doesn’t provide clear in-
formation to the user,
––
time of the user logs and engineering logs is
different.
PATIENT DOSE EVALUATION
AFTER MISSING THE PULSE
As it is regulated, when mistreatment appears, the patient dose
has to be calculated and compared to dose of intent (planned
dose). When difference between prescribed dose and planned
dose is bigger than 10% of total treatment it has to be repor-
ted to the external authority bodies and the reasons have to be
investigated/audited.
The calculations completed for the patient showed that final
dose was different by 1.2% than planned dose (Fig. 6). The in-
cident didn’t have to be reported externally but was reported
internally (the local system of the incidents/adverse events re-
cord) and the adequate action was taken (as described above).
INDEPENDENT DOSE/PULSES
MONITORING SYSTEM
The independent dose/pulse monitoring systemwas implemen-
ted before putting the PDR system back to clinic. That system
detects on-line and actively monitors dose/pulses delivered
during a treatment. The radiation doserate monitoring system
was installed in the treatment room connected via network to
PC running their Mevis Lite 2.2 software (Fig. 7). The doserate
probe is placed in the treatment room far away (the opposite
corner next to the celling) from the patient bad to avoid satu-
ration of it during measurements. The LG6500 probe is a Geiger
Muller Dose Rate Probe with high dose rate and energy range –
adequate to the application (Fig. 8). The system time resolution
is 1 minute – it means that the monitoring systems collects data
for every 1 minute. It is enough to an intended aim. The system
is connected by network to PC and delivered treatment can be
monitored on-line.
Fig. 7
. The doserate monitoring system – the electrometer installed in the control room
Source: Own material.
ADVANTAGES
The doserate monitoring system brought a few advantages to
clinical practice. The most important is that the system is totally
independent on the PDR system, It provides active monitoring
of the treatment remotely and the user can get data on-line and
action when it is needed. The system presents data numerically
as well as the user can get graphical presentation of provided
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