18 March 2016 4D cone-beam CT imaging for guidance in radiation therapy: setup verification by use of implanted fiducial markers
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Abstract
The use of 4D cone-beam computed tomography (CBCT) and fiducial markers for guidance during radiation therapy of mobile tumors is challenging due to the trade-off between image quality, imaging dose, and scanning time. We aimed to investigate the visibility of markers and the feasibility of marker-based 4D registration and manual respiration-induced marker motion quantification for different CBCT acquisition settings. A dynamic thorax phantom and a patient with implanted gold markers were included. For both the phantom and patient, the peak-to-peak amplitude of marker motion in the cranial-caudal direction ranged from 5.3 to 14.0 mm, which did not affect the marker visibility and the associated marker-based registration feasibility. While using a medium field of view (FOV) and the same total imaging dose as is applied for 3D CBCT scanning in our clinic, it was feasible to attain an improved marker visibility by reducing the imaging dose per projection and increasing the number of projection images. For a small FOV with a shorter rotation arc but similar total imaging dose, streak artifacts were reduced due to using a smaller sampling angle. Additionally, the use of a small FOV allowed reducing total imaging dose and scanning time (~2.5 min) without losing the marker visibility. In conclusion, by using 4D CBCT with identical or lower imaging dose and a reduced gantry speed, it is feasible to attain sufficient marker visibility for marker-based 4D setup verification. Moreover, regardless of the settings, manual marker motion quantification can achieve a high accuracy with the error <1.2 mm.
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Peng Jin, Peng Jin, Niek van Wieringen, Niek van Wieringen, Maarten C. C. M. Hulshof, Maarten C. C. M. Hulshof, Arjan Bel, Arjan Bel, Tanja Alderliesten, Tanja Alderliesten, } "4D cone-beam CT imaging for guidance in radiation therapy: setup verification by use of implanted fiducial markers", Proc. SPIE 9786, Medical Imaging 2016: Image-Guided Procedures, Robotic Interventions, and Modeling, 97862N (18 March 2016); doi: 10.1117/12.2216359; https://doi.org/10.1117/12.2216359
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