[Computer-assisted dosimetry system for the monitor calibration of accelerators].
OBJECTIVE
A computerized dosimetry system for calibration of the dose monitor of a medical accelerator was developed with the aim of saving time and reducing errors during measurement and analysis of measured data.


METHODS
The PC-based part of the programme system controls measurements with dosimeters of type Dosimentor using an interface IF4. After transmission of the measured data to an UNIX-network the other part of the programme system serves as a tool for analysis. That means in particular the calculation of the absorbed dose in water per monitor unit and the conversion of measured data to basic data for treatment planning.


RESULTS
In the case of the compact ionization chamber M233641 the relative uncertainty of the monitor calibration amounts to 3.5% and 3.3% for photons and electrons, respectively. Using the flat ionization chamber of Markus type M23343 for measuring electrons a relative measuring uncertainty of 2.1% results.


CONCLUSIONS
For high-energy photons and electrons with energies above 10 MeV the greatest contribution to the relative uncertainty of the monitor calibration is caused by the uncertainty of the calibration factor for the compact ionization chamber M233641. If it is possible to reduce this error to a value of 2% the relative measuring uncertainty would be smaller than 3%. In the case of high-energy electrons it can be concluded that the precision of the monitor calibration is higher with a flat ionization chamber of Markus type M23343 than with a compact ionization chamber M233641.
Seifert
H
H
Institut für Radiologische Physik, Universitätskliniken des Saarlandes, Homburg/Saar.
Licht
N
N
Leetz
H K
HK
D002138:Calibration; D004583:Electrons; D006801:Humans; D010315:Particle Accelerators; D017785:Photons; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy; D012984:Software
Rechnergestütztes Dosimetriesystem zur Monitorkalibrierung von Beschleunigern.