Seminars IFIC

se-fis-med: Multi-institutional study on image quality from novel CBCT solution

1001-Primera-1-1-1 - Paterna. Seminario (Universe)

1001-Primera-1-1-1 - Paterna. Seminario


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Medical Physics Seminar - Seminario de Física Médica

Title: Multi-institutional study on image quality from novel CBCT solution

Author: Lluís Agulles Pedrós, PhD


Researcher at the Department of Radiation Oncology, Queen Elizabeth Cancer Centre, Nova Scotia Health, Halifax, Canada


This study presents a multi-institutional study on image quality provided by a novel cone beam computed tomography (CBCT) platform able to acquire patient images in 6 seconds.   

One Relative Electron Density (RED) phantom and another phantom for image quality, were sent to six institutions for imaging with the novel CBCT with pre-defined protocols, including those used typically in the clinic, with kVp ranging from 100 to 140 kVp and tube current from 80 to 800 mAs. Imaging performance was evaluated with regard to RED vs. Hounsfield Units (HU), uniformity, contrast, slice thickness, circular symmetry, Modulation Transfer Function (MTF), and spatial resolution.   

Some variability was observed among institutions in the RED-to-HU relationship, but only for RED values greater than 1. In this range, RED/HU slopes were 475±25 10-6 RED/HU at 100kVp, 505±20 10-6 RED/HU at 125kVp, and 550±20 10-6 RED/HU at 140kVp. Radial uniformity ranged from 2 to 12 HU, depending on protocol. Circular symmetry for two points 50 mm apart showed consistency within one pixel dimension. Integral non-uniformity was were 3±1 HU, with no difference observed between vertical and horizontal dimensions. Contrast with 1% rods can be observed with 8±5 HU, and for 0.5% rods with 4±2 HU. Spatial resolution given by MTF at 10 % and 50 % yielded values of 0.55±0.1 mm-1 and 0.35±12 mm-1, respectively.   

Multi-institutional analysis of CBCT imaging performance, following imaging of the same phantoms, showed consistency in radial uniformity, circular symmetry, integral non-uniformity, contrast and spatial resolution. Some variability was seen in the RED-to-HU relationship for RED>1 depending on tube current, but still, more data is necessary to establish a clear statistical significance.  


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Organized by

Ana Ros y Fernando Hueso