Editor's Summary and Q&amp;A

Lamichane, Manish; Anderson, Nina K.; Rigali, Paul H.; Seldin, Edward B.; Will, Leslie A.

doi:10.1016/j.ajodo.2009.04.006

Cited by 12 publications

(1 citation statement)

References 0 publications

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“…Most current embodiments of CBCT employ variations of the Feldkamp-Davis-Kress (FDK) algorithm 1 for 3D filtered backprojection, although CBCT will similarly benefit from advances in iterative reconstruction techniques and low-dose protocols. 2 The scope of application-specific CBCT embodiments include dental/maxillofacial imaging, [3][4][5][6][7][8][9][10][11][12][13] temporal bone imaging, [14][15][16] breast imaging, 17 musculoskeletal imaging, 18 image-guided radiotherapy, 19,20 and image-guided surgery. 21,22 Each offers the potential for nearly isotropic, submillimeter spatial resolution combined with soft-tissue contrast resolution approaching that of MDCT (but typically limited by factors such as x-ray scatter, limited field of view (FOV), and increased noise).…”

Section: Introductionmentioning

confidence: 99%

Technical assessment of a cone‐beam CT scanner for otolaryngology imaging: Image quality, dose, and technique protocols

Reh

Carey

et al. 2012

Medical Physics

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Purpose : As cone‐beam CT (CBCT) systems dedicated to various imaging specialties proliferate, technical assessment grounded in imaging physics is important to ensuring that image quality and radiation dose are quantified, understood, and justified. This paper involves technical assessment of a new CBCT scanner (CS 9300, Carestream Health, Rochester, NY) dedicated to imaging of the ear and sinuses for applications in otolaryngology‐head and neck surgery (OHNS). The results guided evaluation of technique protocols to minimize radiation dose in a manner sufficient for OHNS imaging tasks. Methods : The technical assessment focused on the imaging performance and radiation dose for each of seven technique protocols recommended by the manufacturer: three sinus protocols and four ear (temporal bone) protocols. Absolute dose was measured using techniques adapted from AAPM Task Group Report No. 111, involving three stacked 16 cm diameter acrylic cylinders (CTDI phantoms) and a 0.6 cm3 Farmer ionization chamber to measure central and peripheral dose. The central dose (Do) was also measured as a function of longitudinal position (z) within and beyond the primary radiation field to assess, for example, out‐of‐field dose to the neck. Signal‐difference‐to‐noise ratio (SDNR) and Hounsfield unit (HU) accuracy were assessed in a commercially available quality assurance phantom (CATPHAN module CTP404, The Phantom Laboratory, Greenwich, NY) and a custom phantom with soft‐tissue‐simulating plastic inserts (Gammex RMI, Madison, WI). Spatial resolution was assessed both qualitatively (a line‐pair pattern, CATPHAN module CTP528) and quantitatively (modulation transfer function, MTF, measured with a wire phantom). Imaging performance pertinent to various OHNS imaging tasks was qualitatively assessed using an anthropomorphic phantom as evaluated by two experienced OHNS specialists. Results: The technical assessment motivated a variety of modifications to the manufacturer‐specified protocols to provide reduced radiation dose without compromising pertinent task‐based imaging performance. The revised protocols yieldedDo ranging 2.9–5.7 mGy, representing a ∼30% reduction in dose from the original technique chart. Out‐of‐field dose was ∼10% of Do at a distance of ∼8 cm from the field edge. Soft‐tissue contrast resolution was fairly limited (water‐brain SDNR ∼0.4–0.7) while high‐contrast performance was reasonably good (SDNR ∼2–4 for a polystyrene insert in the CATPHAN). The scanner does not demonstrate (or claim to provide) accurate HU and exhibits a systematic error in CT number that could potentially be addressed by further calibration. The spatial resolution is ∼10–16 lp/cm as assessed in a line‐pair phantom, with MTF exceeding 10% out to ∼20 lp/cm. Qualitative assessment by expert readers suggested limited soft‐tissue visibility but excellent high‐contrast (bone) visualization with isotropic spatial resolution suitable to a broad spectrum of pertinent sinus and temporal bone imaging tasks. Conclusions: The CBCT scanner provided spatial an...

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