Article
Treatment planning in proton therapy of ocular tumors
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Published: | September 21, 2010 |
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Outline
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Background: International standard in treatment planning of ocular tumors is EYEPLAN: A spherical eye model is constructed based on ultrasound measurements of the eye length and the tantalum clip positions determined by radiography. The tumor base is delineated on the retina from information of different sources, like fundus composite, ultrasound measurements, and inter-operative measurements. The tumor model is constructed by polynomial interpolation between tumor base and a defined apex. This model is used for treatment planning. The treatment planning system (TPS) presented in this article allows the incorporation of additional imaging modalities.
Methods: OCTOPUS is a special TPS development in cooperation with the German cancer centre (DKFZ) for the treatment of ocular tumors. Additional to the basic features of EYEPLAN, OCTOPUS is able to use images generated by computer tomography, magnet resonance imaging (MRI) and funduscopy for treatment planning.
Results: OCTOPUS enables the creation of more realistic eye models. Especially the positions of organs at risk can be modeled individually. Tumors with a prominence of less than 5 mm can be drawn on the retina; bigger tumors will be overestimated by up to 100% with this method. Therefore delineating the tumor from MRI has many advantages. The real shape of the tumor can be considered in treatment planning, resulting in better protection possibilities for the organs at risk.
Conclusions: At the moment OCTOPUS is the most advanced TPS for ocular tumors.