Automated functional image-guided radiation treatment planning for rectal cancer
- Department of Radiation Oncology, Zurich University Hospital, Zurich (Switzerland)
- Computer Vision Laboratory, Swiss Federal Institute of Technology, Zurich University Hospital, Zurich (Switzerland)
- Department of Nuclear Medicine, Zurich University Hospital, Zurich (Switzerland)
Purpose: Computer tomography-based (CT-based) tumor-volume definition is time consuming and is subject to clinical interpretation. CT is not accessible for standardized algorithms for the purpose of treatment-volume planning. We have evaluated the accuracy of target-volume definition based on the positron emission tomography (PET) data from an integrated PET/CT system with 2-[{sup 18}F]fluoro-2-deoxy-D-glucose (FDG) for standardized target-volume delineation. Materials and Methods: Eleven patients with rectal cancer who were undergoing preoperative radiation therapy (RT) were studied. A standardized region-growing algorithm was tested to replace the CT-derived gross tumor volume by the PET-derived gross tumor volume (PET-GTV) or the biologic target volume (BTV). A software tool was developed to automatically delineate the appropriate tumor volume as defined by the FDG signal, the PET-GTV, and the planning target volume (PTV). The PET-derived volumes were compared with the target volumes from CT. Results: The BTV defined for appropriate GTV assessment was set at a single peak threshold of 40% of the signal of interest. Immediate treatment volume definition based on the choice of a single-tumor volume-derived PET-voxel resulted in a tumor volume that strongly correlated with the CT-derived GTV (r {sup 2} = 0.84; p < 0.01) and the volume as assessed on subsequent anatomic-pathologic analysis (r {sup 2} = 0.77; p < 0.01). In providing sufficient extension margins from the CT-derived GTV and the PET-derived GTV, to PTV, respectively, the correlation of the CT-derived and PET-derived PTV was sufficiently accurate for PTV definition for external-beam therapy (r {sup 2} = 0.96; p < 0.01). Conclusion: Automated segmentation of the PET signal from rectal cancer may allow immediate and sufficiently accurate definition of a preliminary working PTV for preoperative RT. If required, correction for anatomic precision and geometric resolution may be applied in a second step. Computed PET-based target-volume definition could be useful for the definition of standardized simultaneous internal-boost volumes for intensity-modulated radiation therapy (IMRT) based on biologic target volumes.
- OSTI ID:
- 20698594
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 62, Issue 3; Other Information: DOI: 10.1016/j.ijrobp.2004.12.089; PII: S0360-3016(05)00403-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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