Investigation of gated cone-beam CT to reduce respiratory motion blurring Journal Article
| Authors: | Kincaid, R. E. Jr; Yorke, E. D.; Goodman, K. A.; Rimner, A.; Wu, A. J.; Mageras, G. S. |
| Article Title: | Investigation of gated cone-beam CT to reduce respiratory motion blurring |
| Abstract: | Purpose: Methods of reducing respiratory motion blurring in cone-beam CT (CBCT) have been limited to lung where soft tissue contrast is large. Respiration-correlated cone-beam CT uses slow continuous gantry rotation but image quality is limited by uneven projection spacing. This study investigates the efficacy of a novel gated CBCT technique. Methods: In gated CBCT, the linac is programmed such that gantry rotation and kV image acquisition occur within a gate around end expiration and are triggered by an external respiratory monitor. Standard CBCT and gated CBCT scans are performed in 22 patients (11 thoracic, 11 abdominal) and a respiration-correlated CT (RCCT) scan, acquired on a standard CT scanner, from the same day serves as a criterion standard. Image quality is compared by calculating contrast-to-noise ratios (CNR) for tumors in lung, gastroesophageal junction (GEJ) tissue, and pancreas tissue, relative to surrounding background tissue. Congruence between the object in the CBCT images and that in the RCCT is measured by calculating the optimized normalized cross-correlation (NCC) following CBCT-to-RCCT rigid registrations. Results: Gated CBCT results in reduced motion artifacts relative to standard CBCT, with better visualization of tumors in lung, and of abdominal organs including GEJ, pancreas, and organs at risk. CNR of lung tumors is larger in gated CBCT in 6 of 11 cases relative to standard CBCT. A paired two-tailed t-test of lung patient mean CNR shows no statistical significance (p 0.133). In 4 of 5 cases where CNR is not increased, lung tumor motion observed in RCCT is small (range 1.3-5.2 mm). CNR is increased and becomes statistically significant for 6 out of 7 lung patients with > 5 mm tumor motion (p 0.044). CNR is larger in gated CBCT in 5 of 7 GEJ cases and 3 of 4 pancreas cases (p 0.082 and 0.192). Gated CBCT yields improvement with lower NCC relative to standard CBCT in 10 of 11, 7 of 7, and 3 of 4 patients for lung, GEJ, and pancreas images, respectively (p 0.0014, 0.0030, 0.165). Conclusions: Gated CBCT reduces image blurring caused by respiratory motion. The gated gantry rotation yields uniformly and closely spaced projections resulting in improved reconstructed image quality. The technique is shown to be applicable to abdominal sites, where image contrast of soft tissues is low. © 2013 American Association of Physicists in Medicine. |
| Keywords: | clinical article; methodology; sensitivity and specificity; reproducibility; reproducibility of results; biological model; models, biological; lung tumor; registration; image quality; pancreas tumor; artifact; computer simulation; artifacts; esophagus tumor; lower esophagus sphincter; respiratory mechanics; cone beam computed tomography; breathing mechanics; computed tomography scanner; cone-beam computed tomography; radiographic image enhancement; respiratory gated imaging; respiratory-gated imaging techniques; movement; rotation; movement (physiology); image guided radiotherapy; cone-beam ct; image guided radiation therapy; respiratory motion; barium sulfate; radiotherapy, image-guided; motion management; imaging phantom; contrast to noise ratio; four dimensional computed tomography; four-dimensional computed tomography |
| Journal Title: | Medical Physics |
| Volume: | 40 |
| Issue: | 4 |
| ISSN: | 0094-2405 |
| Publisher: | American Association of Physicists in Medicine |
| Date Published: | 2013-04-01 |
| Start Page: | 041717 |
| Language: | English |
| PROVIDER: | scopus |
| PMCID: | PMC3618091 |
| PUBMED: | 23556887 |
| DOI: | 10.1118/1.4795336 |
| DOI/URL: | |
| Notes: | --- - "Export Date: 1 May 2013" - "CODEN: MPHYA" - ":doi 10.1118/1.4795336" - "Source: Scopus" |
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