Hiraku Iramina1, Mitsuhiro Nakamura2, Yusuke Iizuka3, Takamasa Mitsuyoshi3, Yukinori Matsuo3, Takashi Mizowaki3, Masahiro Hiraoka3, Ikuo Kanno4. 1. Department of Nuclear Engineering, Graduate School of Engineering, Kyoto University, Japan; Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Japan. 2. Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Japan. Electronic address: m_nkmr@kuhp.kyoto-u.ac.jp. 3. Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Japan. 4. Department of Nuclear Engineering, Graduate School of Engineering, Kyoto University, Japan.
Abstract
PURPOSE: To quantify the accuracy of extracted target motion trajectories in dual-source four-dimensional cone-beam computed tomography (4D-CBCT) by comparison with the actual three-dimensional (3D) target motion acquired simultaneously during 4D-CBCT scan. MATERIALS AND METHODS: 4D-CBCT scans were performed for 19 different sinusoidal-like patterns and 13 lung cancer patients with implanted markers. Internal (In) or external (Ex) surrogates with amplitude (Amp)- or phase (Ph)-based sorting were used for the reconstructions. The targets were a pseudo-tumor and implanted marker for the phantom and clinical studies, respectively. The accuracy was evaluated by determining the maximum error (MaxEi) between the 3D target position extracted from 4D-CBCT and the actual 3D target position detected by fluoroscopy in each ith phase (0⩽i⩽7). RESULTS: Median peak-to-peak target displacements in the superior-inferior (SI) direction were 20.6 and 20.6mm in the phantom and clinical studies, respectively. In the phantom and clinical studies, the maximum of median MaxEis in the SI direction was 4.6 and 9.2mm in the In_Ph reconstruction. In the clinical study, the maximum of median MaxEis was observed during the end-inhalation phase among all reconstruction approaches. CONCLUSIONS: This study showed the magnitude of underestimation toward the inferior direction of target motion in clinical 4D-CBCT.
PURPOSE: To quantify the accuracy of extracted target motion trajectories in dual-source four-dimensional cone-beam computed tomography (4D-CBCT) by comparison with the actual three-dimensional (3D) target motion acquired simultaneously during 4D-CBCT scan. MATERIALS AND METHODS: 4D-CBCT scans were performed for 19 different sinusoidal-like patterns and 13 lung cancerpatients with implanted markers. Internal (In) or external (Ex) surrogates with amplitude (Amp)- or phase (Ph)-based sorting were used for the reconstructions. The targets were a pseudo-tumor and implanted marker for the phantom and clinical studies, respectively. The accuracy was evaluated by determining the maximum error (MaxEi) between the 3D target position extracted from 4D-CBCT and the actual 3D target position detected by fluoroscopy in each ith phase (0⩽i⩽7). RESULTS: Median peak-to-peak target displacements in the superior-inferior (SI) direction were 20.6 and 20.6mm in the phantom and clinical studies, respectively. In the phantom and clinical studies, the maximum of median MaxEis in the SI direction was 4.6 and 9.2mm in the In_Ph reconstruction. In the clinical study, the maximum of median MaxEis was observed during the end-inhalation phase among all reconstruction approaches. CONCLUSIONS: This study showed the magnitude of underestimation toward the inferior direction of target motion in clinical 4D-CBCT.
Authors: Chun-Chien Shieh; Vincent Caillet; Michelle Dunbar; Paul J Keall; Jeremy T Booth; Nicholas Hardcastle; Carol Haddad; Thomas Eade; Ilana Feain Journal: Phys Med Biol Date: 2017-03-21 Impact factor: 3.609