  In recent years, the use of PACS for radiation therapy has become the norm in
hospital environment and has suggested for collecting data and management from
different TPSs with DICOM objects. However, some TPS does not provide the DVH
exportation with text or other format. In addition, plan review systems for
various TPSs often allow DVH recalculation with different algorithms. These
algorithms result in the inevitable discrepancy between the values obtained
with the recalculation and those obtained with TPS itself. The purpose of this
study was to develop a simple method for generating reproducible DVH values
obtained from the TPSs. Treatment planning information including structures and
delivered dose was exported by the DICOM format from planning systems. The
supersampling and trilinear interpolation methods were employed to calculate
DVH data from 35 treatment plans. The discrepancies between DVHs extracted from
each TPS and the proposed calculation method were evaluated with respect to the
supersampling ratio. The volume, minimum dose, maximum dose, and mean dose were
compared. The variation of DVHs from multiple TPSs was compared with a
commercially available treatment planning comparison tool. The overall
comparisons of the volume, minimum dose, maximum dose, and mean dose showed
that the proposed method generated relatively smaller discrepancies compared
with TPS than those by MIM software and TPS. As the structure volume decreased,
the overall percent difference increased. Most large difference was observed in
the small organs such as eye ball, lens, optic nerve which had below 10 cc
volume. A simple and useful technique was developed to generate DVH with
acceptable error from a proprietary TPS. This study provides the convenient and
common framework which allows to use a single well-managed storage solution for
the independent information system.
