Pilot study of the IAEA protocol for clinical commissioning of treatment planning systems

Clinical test cases to facilitate the commissioning process of radiotherapy treatment planning system (TPS) were developed by participants of the IAEA coordinated research project (CRP) on 'Development of procedures for quality assurance for dosimetry calculation in radiotherapy'. The tests cover basic treatment techniques in typical radiotherapy installations and are based on the use of CIRS torso phantom. The practicability of the commissioning tests is assured through their trial use in the clinical facilities of different sizes. All hospitals used the same type of phantom which was scanned twice with computer tomography (CT). At the first scan different inserts were introduced into the phantom to derive the CT number to relative electron density conversion curve. At the second scan the phantom CT slices were acquired for planning of different clinical test cases on TPS. The dose was measured with ionization chamber placed inside the phantom. In this work we present the results from eleven hospitals which are using fifteen different TPSs. Altogether there are 37 different combinations of algorithms and beam qualities. The use of the phantom and the tests proposed in the CRP enabled the evaluation of accuracy and limitations of different algorithms as well as inconsistencies in the loaded data. The differences between TPS dose calculations and measurements for different photon beam algorithms and inhomogeneity correction methods which exceed 3% tolerance limit are shown. More results for different clinical test cases as well as test descriptions will be presented at the conference. Results of the pilot study have shown that proposed test cases can not only serve to ensure the safe use of the TPS in a specific clinic, but may also help the user to appreciate the possibilities of their system and understand its limitations. The set of tests for clinical commissioning can be performed in reasonable time in the majority of hospitals, particularly in those with limited resources)