Dose recalculation in megavoltage cone-beam CT for treatment evaluation: Removal of cupping and truncation artefacts in scans of the thorax and abdomen |
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Authors: | Steven F. Petit,Wouter J.C. van Elmpt,Philippe Lambin,André L.A.J. Dekker |
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Affiliation: | Department of Radiation Oncology (MAASTRO Clinic), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands |
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Abstract: | PurposeTo 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 methodsMVCBCT 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.ResultsThe 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.ConclusionsThe 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. |
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Keywords: | Megavoltage cone-beam CT (MVCBCT) Cupping artefacts Truncation artifacts Dose recalculation Dose reconstruction Treatment evaluation |
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