The tuning fork artifact in computerized tomography

Shepp, Larry; Hilal, S. K.; Schulz, Raymond

doi:10.1016/0146-664x(79)90004-2

Cited by 73 publications

(40 citation statements)

References 2 publications

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“…This change with time is not accounted for in the image reconstruction, and hence artifacts are expected [1][2][3][4][5] . From both the gated and non-gated images acquired during the simulated respiration experiments, the images with the 'worst' artifacts (as determined by the author's visual inspection) were identified.…”

Section: Image Artifactsmentioning

confidence: 99%

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Potential radiotherapy improvements with respiratory gating

Keall

Kini

Vedam

et al. 2002

Australas. Phys. Eng. Sci. Med.

148

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Gating is a relatively new and potentially useful therapeutic addition to external beam radiotherapy applied to regions affected by intra-fraction motion. The impact was of gating on treatment margins, image artifacts, and volume and positional accuracy was investigated by CT imaging of sinusoidally moving spheres. The motion of the spheres simulates target motion. During the CT imaging of dynamically moving spheres, gating reproduced the static volume to within 1%, whereas errors of over 20% were observed where gating was not used. Using a theoretical analysis of margins, gating alone or in combination with an electronic portal imaging device may allow a 2-11 mm reduction in the CTV to PTV margin, and thus less healthy tissue need be irradiated. Gating may allow a reduction of treatment margins, an improvement in image quality, and an improvement in positional and volumetric accuracy of the gross tumor volume.

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Section: Image Artifactsmentioning

confidence: 99%

“…Respiration motion also causes artifacts during image acquisition, such as warping of the target volume and incorrect positional and volumetric information [1][2][3][4][5] . An example of incorrect positional and volumetric information during CT imaging due to respiration motion is shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Potential radiotherapy improvements with respiratory gating

Keall

Kini

Vedam

et al. 2002

Australas. Phys. Eng. Sci. Med.

148

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show abstract

“…Respiratory motion degrades anatomic position reproducibility during imaging [1][2][3][4][5][6][7][8][9][10][11] necessitates larger margins during radiotherapy planning 12,13 and causes errors during radiation delivery [14][15][16][17][18][19] . Clinically significant lung tumor motion cannot be predicted by any known clinical parameters 20 , suggesting that tumor motion must be explicitly determined for each patient.…”

Section: Introductionmentioning

confidence: 99%

Respiratory regularity gated 4D CT acquisition: concepts and proof of principle

Keall

Vedam

George

et al. 2007

Australas. Phys. Eng. Sci. Med.

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Four-dimensional CT images are generally sorted through a post-acquisition procedure correlating images with a time-synchronized external respiration signal. The patient's ability to maintain reproducible respiration is the limiting factor during 4D CT, where artifacts occur in approximately 85% of scans with current technology. To reduce these artifacts and their subsequent effects during radiotherapy planning, a method for improved 4D CT image acquisition that relies on gating 4D CT acquisition based on the real time monitoring of the respiration signal has been proposed. The respiration signal and CT data acquisition are linked, such that data from irregular breathing cycles, which cause artifacts, are not acquired by gating CT acquisition by the respiratory signal. A proof-of-principle application of the respiratory regularity gated 4D CT method using patient respiratory signals demonstrates the potential of this method to reduce artifacts currently found in 4D CT scans. Numerical simulations indicate a potential reduction in motion within a respiratory phase bin by 20-40% depending on tolerances chosen. Additional advantages of the proposed method are dose reduction by eliminating unnecessary oversampling and obviating the need for post-processing to create the 4D CT data set.

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“…However, full realization of IMRT's advantages are limited by target and normal tissue positioning uncertainties, including internal organ motion and tissue deformation. [1][2][3] For example, if not explicitly accounted for, respiratory motion can negatively affect the imaging, [4][5][6][7] planning, 8,9 and delivery 10,11 in radiation therapy. To alleviate the negative impact of this motion, respiratory gating and breath-hold radiotherapy methods have been clinically applied at a number of institutions.…”

Section: Introductionmentioning

confidence: 99%

A method to evaluate dose errors introduced by dose mapping processes for mass conserving deformations

et al. 2012

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Purpose: To present a method to evaluate the dose mapping error introduced by the dose mapping process. In addition, apply the method to evaluate the dose mapping error introduced by the 4D dose calculation process implemented in a research version of commercial treatment planning system for a patient case. Methods: The average dose accumulated in a finite volume should be unchanged when the dose delivered to one anatomic instance of that volume is mapped to a different anatomic instance-provided that the tissue deformation between the anatomic instances is mass conserving. The average dose to a finite volume on image S is defined as d S ¼ e s =m S , where e S is the energy deposited in the mass m S contained in the volume. Since mass and energy should be conserved, when d S is mapped to an image Rðd S!R ¼ d R Þ, the mean dose mapping error is defined aswhere the e R and e S are integral doses (energy deposited), and m R and m S are the masses within the region of interest (ROI) on image R and the corresponding ROI on image S, where R and S are the two anatomic instances from the same patient. Alternatively, application of simple differential propagation yields the differential dose mapping error,

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The tuning fork artifact in computerized tomography

Cited by 73 publications

References 2 publications

Potential radiotherapy improvements with respiratory gating

Potential radiotherapy improvements with respiratory gating

Respiratory regularity gated 4D CT acquisition: concepts and proof of principle

A method to evaluate dose errors introduced by dose mapping processes for mass conserving deformations

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