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Dynamic detector offsets for field of view extension in C‐arm computed tomography with application to weight‐bearing imaging
Author(s) -
Herbst Magdalena,
Schebesch Frank,
Berger Martin,
Choi JangHwan,
Fahrig Rebecca,
Hornegger Joachim,
Maier Andreas
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4915542
Subject(s) - detector , field of view , offset (computer science) , imaging phantom , image quality , physics , ellipsoid , optics , computer vision , computer science , artificial intelligence , image (mathematics) , astronomy , programming language
Purpose: In C‐arm computed tomography (CT), the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g., a full hip or thorax. Proposed methods to extend the FOV use a fixed detector displacement and a 360° scan range to double the radius of the FOV. These trajectories are designed for circular FOVs. However, there are cases in which the required FOV is not circular but rather an ellipsoid.Methods: In this work, the authors show that in fan‐beam CT, the use of a dynamically adjusting detector offset can reduce the required scan range when using a noncircular FOV. Furthermore, the authors present an analytic solution to determine the minimal required scan ranges for elliptic FOVs given a certain detector size and an algorithmic approach for arbitrary FOVs.Results: The authors show that the proposed method can result in a substantial reduction of the required scan range. Initial reconstructions of data sets acquired with our new minimal trajectory yielded image quality comparable to reconstructions of data acquired using a fixed detector offset and a full 360° rotation.Conclusions: Our results show a promising reduction of the necessary scan range especially for ellipsoidal objects that extend the FOV. In noncircular FOVs, there exists a set of solutions that allow a trade‐off between detector size and scan range.