Author(s)

Ronnie W. K. Leung, Matthew Y. P. Wong, Venus W. Y. Lee, Steven K. T. Cheung, Aray K. L. Wong, Hollis S. L. Luk, Francesca K. L. Ng, Gilbert M. L. Law, Frankle K. H. Lee, W. H. Mui, Dennis Y. K. Ngar

Department of Clinical Oncology, Tuen Mun Hospital, Hong Kong, China.

Introduction: To investigate the inter-observer and inter-modality variabilities of two imaging guided equipments—cone-beam computed tomography (CBCT) and ultrasound (US) in kidney stereotactic body radiotherapy. Methods: A renal metastasis case implanted with three gold anchor fiducial markers was firstly scanned by US to acquire a 3-dimension US image and followed by 4-dimension CBCT in every fraction. Seven observers retrospectively registered the pre-treatment images with the corresponding reference images based on the gold markers. Registration uncertainty of the observers between two imaging modalities was evaluated. Results: The uncertainties over whole treatment course in CBCT were 0.88 mm, 1.94 mm and 0.86 mm in lateral, longitudinal and vertical directions respectively; while 0.8 mm, 0.97 mm and 1.36 mm were found in US. Conclusion: The greatest uncertainty was found in longitudinal direction in CBCT due to the fact that the respiration motion is the most rigorous in cranial-caudal direction. In US, since the probe was hold almost in upright position, the strong echo in vertical direction was attributed to the greatest uncertainty for such direction.

Inter-Observer, Inter-Modality, Variability, CBCT, US, Kidney SBRT

Leung, R. , Wong, M. , Lee, V. , Cheung, S. , Wong, A. , Luk, H. , Ng, F. , Law, G. , Lee, F. , Mui, W. and Ngar, D. (2017) A Technical Note: Inter-Observer and Inter-Modality Variability of Cone-Beam Computed Tomography (CBCT) and Ultrasound (US) in Stereotactic Body Radiotherapy for Kidney Cancer. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 6, 392-400. doi: 10.4236/ijmpcero.2017.64035.