Dose recalculation in megavoltage cone-beam CT for treatment evaluation: Removal of cupping and truncation artefacts in scans of the thorax and abdomen

Abstract Purpose To correct megavoltage cone-beam CT (MVCBCT) images of the thorax and abdomen for cupping and truncation artefacts to reconstruct the 3D-delivered dose distribution for treatment evaluation. Materials and methods MVCBCT scans of three phantoms, three lung and two rectal cancer patie...

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Bibliographic Details
Published in:Radiotherapy and oncology 2010-03, Vol.94 (3), p.359-366
Main Authors: Petit, Steven F, van Elmpt, Wouter J.C, Lambin, Philippe, Dekker, André L.A.J
Format: Article
Language:English
Subjects:
Abdomen - diagnostic imaging
Algorithms
Cone-Beam Computed Tomography
Cupping artefacts
Dose recalculation
Dose reconstruction
Hematology, Oncology and Palliative Medicine
Humans
Lung Neoplasms - radiotherapy
Megavoltage cone-beam CT (MVCBCT)
Phantoms, Imaging
Radiotherapy Dosage
Rectal Neoplasms - radiotherapy
Thorax - diagnostic imaging
Treatment evaluation
Treatment Outcome
Truncation artifacts
Ultrasonography
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Summary:Abstract Purpose To correct megavoltage cone-beam CT (MVCBCT) images of the thorax and abdomen for cupping and truncation artefacts to reconstruct the 3D-delivered dose distribution for treatment evaluation. Materials and methods MVCBCT scans of three phantoms, three lung and two rectal cancer patients were acquired. The cone-beam projection images were iteratively corrected for cupping and truncation artefacts and the resulting primary transmission was used for cone-beam reconstruction. The reconstructed scans were merged into the planning CT scan (MVCBCT+). Dose distributions of clinical IMRT, stereotactic and conformal treatment plans were recalculated on the uncorrected and corrected MVCBCT+ scans using the treatment planning system and compared to the planned dose distribution. Results The dose distributions on the corrected MVCBCT+ of the phantoms were accurate for 99% of the voxels within 2% or 2 mm. Using this method the errors in mean GTV dose reduced from about 10% to 1% for the patients. Conclusions The method corrects cupping and truncation artefacts in cone-beam scans of the thorax and abdomen in addition to head-and-neck (demonstrated previously). The corrected scans can be used to calculate the influence of anatomical changes on the 3D-delivered dose distribution.
ISSN:0167-8140
1879-0887
DOI:10.1016/j.radonc.2009.12.001