Are multiple CT scans required for planning curative radiotherapy in lung tumors of the lower lobe?

Koste, John R. van Sörnsen de; Lagerwaard, Frank J.; Boer, Hans C.J. de; Nijssen-Visser, Margriet R.J; Senan, Suresh

doi:10.1016/s0360-3016(02)04602-3

Cited by 67 publications

(20 citation statements)

References 13 publications

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“…However, as shown in Fig 4, aliasing errors still exist in the reconstructed projection data. While slow-scan techniques generate target volumes larger than fast-scan target volumes, and while slow-scan generated images appear to be more reproducible and seem to approximate the time-average motion profile [10,11], this was shown true only from analytical/simulation studies. Findings in this study showed a perceptible dependence of reconstructed volume on the temporal relationship between initial target motion-phase and initial angle of x-ray source, as illustrated in as well as Fig 7 and 8 (acquisitions in series 3 and 4) for two different initial motion phases.…”

Section: Discussionmentioning

confidence: 99%

Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning

Tanyi

Fuß

Varchena³

et al. 2007

Radiat Oncol

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Purpose: To quantify volumetric and positional aliasing during non-gated fast-and slow-scan acquisition CT in the presence of 3D target motion. Methods:Single-slice fast, single-slice slow, and multi-slice fast scan helical CTs were acquired of dynamic spherical targets (1 and 3.15 cm in diameter), embedded in an anthropomorphic phantom. 3D target motions typical of clinically observed tumor motion parameters were investigated. Motion excursions included ± 5, ± 10, and ± 15 mm displacements in the S-I direction synchronized with constant displacements of ± 5 and ± 2 mm in the A-P and lateral directions, respectively. For each target, scan technique, and motion excursion, eight different initial motion-to-scan phase relationships were investigated.Results: An anticipated general trend of target volume overestimation was observed. The mean percentage overestimation of the true physical target volume typically increased with target motion amplitude and decreasing target diameter. Slow-scan percentage overestimations were larger, and better approximated the time-averaged motion envelope, as opposed to fast-scans. Motion induced centroid misrepresentation was greater in the S-I direction for fast-scan techniques, and transaxial direction for the slow-scan technique. Overestimation is fairly uniform for slice widths < 5 mm, beyond which there is gross overestimation. Conclusion:Non-gated CT imaging of targets describing clinically relevant, 3D motion results in aliased overestimation of the target volume and misrepresentation of centroid location, with little or no correlation between the physical target geometry and the CT-generated target geometry. Slow-scan techniques are a practical method for characterizing time-averaged target position. Fastscan techniques provide a more reliable, albeit still distorted, target margin.

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Section: Discussionmentioning

confidence: 99%

Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning

Tanyi

Fuß

Varchena³

et al. 2007

Radiat Oncol

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“…Giraud et al 30 suggested GTV to CTV margins of 0.6 to 0.8 cm, whereas other studies used a value of 0.5 cm. 31 Setup errors are typically reported to be between 0.3 and 0.5 cm, 32,33 and additional margins in the range typically of 0.5 cm were applied to accommodate internal mobility, contouring uncertainties, and residual inter-and intrafractional motion. 31,34,35 The OARs (heart, esophagus, spinal cord, and lung) were contoured on 4 image series: EOE, EOI, MIP, and AVE datasets.…”

Section: Patient Datasetsmentioning

confidence: 99%

Investigation of Simple IMRT Delivery Techniques for Non-Small Cell Lung Cancer Patients with Respiratory Motion Using 4DCT

et al. 2009

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“…The study concluded that the use of slow planning CT scans enables the drawing of tighter margins in external beam treatment planning of lung cancer. van Sö rnsen de Koste et al [9] also found that slow CT scans generated larger and more reproducible target volumes than rapid planning scans. The study concluded that PTVs derived using slow CT produced superior target coverage to that using conventional scans.…”

mentioning

confidence: 96%

“…Most of the published investigations of slow CT use scanners capable of gantry rotation speeds down to 4.0 s per rotation [8,9,13,14]. The aim of this study is to determine whether slow CT can be implemented on a modern CT scanner capable of rotation speeds only down to 1.5 s per rotation, and the magnitude of the benefits that this could provide for target volume delineation and target location identification.…”

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confidence: 99%

The potential for undertaking slow CT using a modern CT scanner

Chinneck

McJury²,

Hounsell³

2010

BJR

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ABSTRACT. Respiratory motion complicates target volume definition for patients with lung cancer. The use of slow CT to aid in the definition of moving target volumes was investigated. Standard and slow scans of an oscillating phantom were acquired using gantry rotation periods of 0.8 and 1.5 s and pitches of 0.95 and 0.50, respectively. The resultant images of three spheres within the phantom, labelled as A, B and C with diameters of 3.7, 2.8 and 2.2 cm, were analysed. The central co-ordinates of each volume were determined, and the ratio of the target volume outlined on CT (TV CT ) to the true target volume (TV) was calculated. For 1.5 cm peak-to-trough (PTT) motion, standard CT mean ratios of 0.8, 0.8 and 0.7 were obtained for spheres A, B and C, respectively, whereas slow CT resulted in a mean ratio of 0.9 for all three spheres. For 2.5 cm motion, standard CT mean ratios of 0.8, 0.7 and 0.7 were obtained, whereas the slow CT mean ratios were 0.9, 0.9 and 0.8. The deviation of the central co-ordinate for the slow CT volumes was within 0.1 cm whereas deviations of up to 0.7 cm were seen using standard CT. This study indicates the potential benefit of using slow CT, even on modern scanners capable of rotation periods only down to 1.5 s, to define moving target volumes more accurately and reproducibly moving target volumes, and aid in the management of respiratory motion for patients with lung cancer.

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Are multiple CT scans required for planning curative radiotherapy in lung tumors of the lower lobe?

Cited by 67 publications

References 13 publications

Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning

Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning

Investigation of Simple IMRT Delivery Techniques for Non-Small Cell Lung Cancer Patients with Respiratory Motion Using 4DCT

The potential for undertaking slow CT using a modern CT scanner

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