Image quality and localization accuracy in C-arm tomosynthesis-guided head and neck surgery

G. Bachar, J. H. Siewerdsen*, M. J. Daly, D. A. Jaffray, J. C. Irish

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The image quality and localization accuracy for C-arm tomosynthesis and cone-beam computed tomography (CBCT) guidance of head and neck surgery were investigated. A continuum in image acquisition was explored, ranging from a single exposure (radiograph) to multiple projections acquired over a limited arc (tomosynthesis) to a full semicircular trajectory (CBCT). Experiments were performed using a prototype mobile C-arm modified to perform 3D image acquisition (a modified Siemens PowerMobil). The tradeoffs in image quality associated with the extent of the source-detector arc (θtot), the number of projection views, and the total imaging dose were evaluated in phantom and cadaver studies. Surgical localization performance was evaluated using three cadaver heads imaged as a function of θtot. Six localization tasks were considered, ranging from high-contrast feature identification (e.g., tip of a K-wire pointer) to more challenging soft-tissue delineation (e.g., junction of the hard and soft palate). Five head and neck surgeons and one radiologist participated as observers. For each localization task, the 3D coordinates of landmarks pinpointed by each observer were analyzed as a function of θtot. For all tomosynthesis angles, image quality was highest in the coronal plane, whereas sagittal and axial planes exhibited a substantial decrease in spatial resolution associated with out-of-plane blur and distortion. Tasks involving complex, lower-contrast features demonstrated steeper degradation with smaller tomosynthetic arc. Localization accuracy in the coronal plane was correspondingly high, maintained to <3 mm down to θtot ∼30°, whereas sagittal and axial localization degraded rapidly below θtot ∼60°. Similarly, localization precision was better than ∼1 mm within the coronal plane, compared to ∼2-3 mm out-of-plane for tomosynthesis angles below θtot ∼45°. An overall 3D localization accuracy of ∼2.5 mm was achieved with θtot ∼ 90° for most tasks. The high in-plane spatial resolution, short scanning time, and low radiation dose characteristic of tomosynthesis may enable the surgeon to collect near real-time images throughout the procedure with minimal interference to surgical workflow. Therefore, tomosynthesis could provide a useful addition to the image-guided surgery arsenal, providing on-demand, high quality image updates, complemented by CBCT at critical milestones in the surgical procedure.

Original languageEnglish
Pages (from-to)4664-4677
Number of pages14
JournalMedical Physics
Volume34
Issue number12
DOIs
StatePublished - 2007
Externally publishedYes

Keywords

  • C-arm
  • Cone-beam CT
  • Flat-panel detector
  • Image quality
  • Image-guided interventions
  • Image-guided surgery
  • Tomosynthesis

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