Simultaneous {sup 68}Ga-DOTATOC-PET/MRI for IMRT Treatment Planning for Meningioma: First Experience

Journal Article · Thu Sep 01 00:00:00 EDT 2011 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2010.10.078· OSTI ID:21587699

Thorwarth, Daniela ^[1]; Henke, Guido; Mueller, Arndt-Christian ^[2]; Reimold, Matthias ^[3]; Beyer, Thomas ^[4]; Boss, Andreas ^[5]; Kolb, Armin; Pichler, Bernd ^[6]; Pfannenberg, Christina ^[5]

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1. Section of Biomedical Physics, University Hospital for Radiation Oncology, Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany)
2. Department of Radiation Oncology, University Hospital for Radiation Oncology, Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany)
3. Department of Nuclear Medicine, University Hospital for Radiology, Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany)
4. Imaging Science Institute, University Hospital, Eberhard-Kars-Universitaet Tuebingen, Tuebingen (Germany)
5. Department of Diagnostic and Interventional Radiology, University Hospital for Radiology, Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany)
6. Laboratory of Preclinical Imaging and Imaging Technology of the Werner Siemens-Foundation, University Hospital for Radiology, Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany)

Purpose: To evaluate intensity-modulated radiotherapy (IMRT) treatment planning based on simultaneous positron-emission tomography and magnetic resonance imaging (PET/MRI) of meningioma. Methods and Materials: A meningioma patient was examined prior to radiotherapy with dedicated planning computed tomography (CT), MRI, PET/CT with gallium-68-labeled DOTATOC ({sup 68}Ga-DOTATOC), and simultaneous {sup 68}Ga-DOTATOC-PET/MRI. The first gross target volume (GTV) was defined based on a combination of separate MR and {sup 68}Ga-DOTATOC-PET/CT imaging (GTV{sub PET/CT+MR}). Then, the simultaneous PET/MR images were used to delineate a second GTV (GTV{sub PET/MR}) by following exactly the same delineation strategy. After an isotropic expansion of those volumes by a 4-mm safety margin, the resulting planning target volumes (PTVs) were compared by calculating the intersection volume and the relative complements. A cross-evaluation of IMRT plans was performed, where the treatment plan created for the PTV{sub PET/CT+MR} was applied to the PET/MR-based PTV{sub PET/MR}. Results: Generally, target volumes for IMRT treatment planning did not differ between MRI plus {sup 68}Ga-DOTATOC-PET/CT and simultaneous PET/MR imaging. Only in certain regions of the GTV were differences observed. The overall volume of the PET/MR-based PTV was approximately the same as that obtained from PET/CT data. A small region of infiltrative tumor growth next to the main tumor mass was better visualized with combined PET/MR due to smaller PET voxel sizes and improved recovery. An IMRT treatment plan was optimized for the PTV{sub PET/CT+MR}. The evaluation of this plan with respect to the PTV{sub PET/MR} showed parts of the target volume that would not have received the full radiation dose after delineation of the tumor, based on simultaneous PET/MR. Conclusion: This case showed that differences in target volumes delineated on the basis of separate MR and PET/CT and simultaneous PET/MR may be observed that can have significant consequences for an effectively applied radiotherapy treatment plan.

• OSTI ID: 21587699
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 1 Vol. 81; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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