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

Abstract

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.

A decision tool for radiographer-led abdominal image-guided stereotactic ablative body radiotherapy – Experience from a single institution

“…In addition, image-guided radiotherapy (IGRT) using cone beam computed tomography (CBCT) can be challenging due to poor contrast within the abdomen, especially with motion-associated artifacts [1] . Uncertainties in CBCT matching can lead to variation in overall match between users which can lead to an increase in the length of time before treatment delivery [2] . The time interval between imaging and treatment delivery should be kept as short as possible to minimise the risk of intrafraction motion changes [3] , [4] .…”