A Method to Estimate Mean Position, Motion Magnitude, Motion Correlation, and Trajectory of a Tumor From Cone-Beam CT Projections for Image-Guided Radiotherapy

Poulsen, Per Rugaard; Cho, Byungchul; Keall, Paul J.

doi:10.1016/j.ijrobp.2008.07.037

Cited by 82 publications

(112 citation statements)

References 14 publications

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“…Recently, we developed a method for target trajectory estimation from a sequence of X-ray images acquired by a single rotating imager such as the projection images in a cone-beam CT scan (16). For each image in the sequence, the three-dimensional (3D) target position was estimated by combined use of all images in the sequence, both the preceding and the subsequent images.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Multileaf Collimator Tracking of Respiratory Target Motion Based on a Single Kilovoltage Imager During Arc Radiotherapy

Poulsen

Cho

Ruan

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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Section: Introductionmentioning

confidence: 99%

Dynamic Multileaf Collimator Tracking of Respiratory Target Motion Based on a Single Kilovoltage Imager During Arc Radiotherapy

Poulsen

Cho

Ruan

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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“…After manual correction of the failed segmentations, the resulting projected marker trajectory was used to estimate the 3D marker trajectory. 1 Finally, the normalized cross correlation between the template and the CBCT projection was analyzed for all segmentations in order to investigate if a low cross correlation could be used for segmentation failure detection. Figure 2 summarizes the segmentation for one of the three Visicoil markers.…”

Section: Iib Segmentation Examplesmentioning

confidence: 99%

“…For patients with implanted tumor markers, the CBCT projections provide the target trajectory projected into a 2D rotating coordinate system. The projected trajectory can be used to estimate the three dimensional ͑3D͒ target trajectory either retrospectively for tumor motion analysis 1 or-at a modest cost of accuracy-in real time for tumor motion tracking. 2,3 It requires reliable marker segmentation in the CBCT projections.…”

Section: Introductionmentioning

confidence: 99%

A method for robust segmentation of arbitrarily shaped radiopaque structures in cone‐beam CT projections

et al. 2011

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Purpose: Implanted markers are commonly used in radiotherapy for x-ray based target localization. The projected marker position in a series of cone-beam CT ͑CBCT͒ projections can be used to estimate the three dimensional ͑3D͒ target trajectory during the CBCT acquisition. This has important applications in tumor motion management such as motion inclusive, gating, and tumor tracking strategies. However, for irregularly shaped markers, reliable segmentation is challenged by large variations in the marker shape with projection angle. The purpose of this study was to develop a semiautomated method for robust and reliable segmentation of arbitrarily shaped radiopaque markers in CBCT projections. Methods: The segmentation method involved the following three steps: ͑1͒ Threshold based segmentation of the marker in three to six selected projections with large angular separation, good marker contrast, and uniform background; ͑2͒ construction of a 3D marker model by coalignment and backprojection of the threshold-based segmentations; and ͑3͒ construction of marker templates at all imaging angles by projection of the 3D model and use of these templates for template-based segmentation. The versatility of the segmentation method was demonstrated by segmentation of the following structures in the projections from two clinical CBCT scans: ͑1͒ Three linear fiducial markers ͑Visicoil͒ implanted in or near a lung tumor and ͑2͒ an artificial cardiac valve in a lung cancer patient. Results: Automatic marker segmentation was obtained in more than 99.9% of the cases. The segmentation failed in a few cases where the marker was either close to a structure of similar appearance or hidden behind a dense structure ͑data cable͒. Conclusions: A robust template-based method for segmentation of arbitrarily shaped radiopaque markers in CBCT projections was developed.

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“…Kilovoltage Intrafraction Monitoring (KIM) takes advantage of the gantry‐mounted kV imager available on many modern linear accelerators to determine the position of the prostate in three dimensions from 2D kV projections using a probability density function 15, 16. The geometrical accuracy of KIM has been established, and the software has successfully been used to measure prostate displacement during treatment in noninterventional17 and interventional studies 18…”

Section: Introductionmentioning

confidence: 99%

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

Legge

Nguyen

et al. 2017

J Applied Clin Med Phys

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BackgroundKilovoltage Intrafraction Monitoring (KIM) is a method which determines the three‐dimensional position of the prostate from two‐dimensional kilovoltage (kV) projections taken during linac based radiotherapy treatment with real‐time feedback. Rectal displacement devices (RDDs) allow for improved rectal dosimetry during prostate cancer treatment. This study used KIM to perform a preliminary investigation of prostate intrafraction motion observed in patients with an RDD in place.MethodsTen patients with intermediate to high‐risk prostate cancer were treated with a Rectafix RDD in place during two boost fractions of 9.5–10 Gy delivered using volumetric modulated arc therapy (VMAT) on Clinac iX and Truebeam linacs. Two‐dimensional kV projections were acquired during treatment. KIM software was used following treatment to determine the displacement of the prostate over time. The displacement results were analyzed to determine the percentage of treatment time the prostate spent within 1 mm, between 1 and 2 mm, between 2 and 3 mm and greater than 3 mm from its initial position.Results KIM successfully measured displacement for 19 prostate stereotactic boost fractions. The prostate was within 1 mm of its initial position for 84.8%, 1–2 mm for 14%, 2–3 mm 1.2% and ≥3 mm only 0.4% of the treatment time.ConclusionsIn this preliminary study using KIM, KIM was successfully used to measure prostate intrafraction motion, which was found to be small in the presence of a rectal displacement device.Trial registrationThe Hunter New England Human Research Ethics Committee reference number is 14/08/20/3.01.

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A Method to Estimate Mean Position, Motion Magnitude, Motion Correlation, and Trajectory of a Tumor From Cone-Beam CT Projections for Image-Guided Radiotherapy

Cited by 82 publications

References 14 publications

Dynamic Multileaf Collimator Tracking of Respiratory Target Motion Based on a Single Kilovoltage Imager During Arc Radiotherapy

Dynamic Multileaf Collimator Tracking of Respiratory Target Motion Based on a Single Kilovoltage Imager During Arc Radiotherapy

A method for robust segmentation of arbitrarily shaped radiopaque structures in cone‐beam CT projections

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

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