Metal artifact reduction through MVCBCT and kVCT in radiotherapy

Area of Science:

• Medical Imaging
• Radiotherapy Physics

Background:

• Metal artifacts significantly degrade computed tomography (CT) image quality.
• Artifacts in CT images can lead to inaccurate radiotherapy planning and dose calculations.

Purpose of the Study:

• To develop and validate a new method for metal artifact reduction in kilovoltage CT (kVCT) and megavoltage cone beam CT (MVCBCT) images.
• To assess the impact of artifact reduction on radiotherapy plan accuracy.

Main Methods:

• Combined kVCT and MVCBCT images to create a prior image.
• Forward projected the prior image to generate surrogate data for metal trace replacement.
• Reconstructed the corrected image using filtered back projection.
• Designed radiotherapy plans using theoretical, uncorrected, and corrected CT images.

Main Results:

• The novel method effectively removed most metal artifacts, restoring accurate CT values.
• Internal structures within metal implants, like hollow holes, were accurately visualized in corrected images.
• Dose distributions calculated from corrected images closely matched those from theoretical CT images.
• Uncorrected images failed to show internal metal structures and led to inaccurate dose calculations.

Conclusions:

• Combining kVCT and MVCBCT data significantly improves CT image quality in the presence of large metal implants.
• The proposed artifact reduction technique enhances the accuracy of radiotherapy planning and dose calculation.