Date: 31 May 2013

Respiratory Motion Correction in Cone-Beam CT for Image-Guided Radiotherapy

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Abstract

Cone-beam CT has been integrated with the linear accelerator for image-guided radiotherapy, i.e., the accurate assessment and correction of the target position prior to treatment delivery. The slowness of these cone-beam CT scanners, which rotate at less than 1 rpm, induces respiratory motion artifacts if the patient can breath freely during the acquisition. As in conventional CT, several techniques have been proposed to correct for these artifacts. Respiration-correlated cone-beam CT assumes that respiratory motion is periodic to sort the cone-beam projection images in subsets according to a respiratory signal, and reconstructs from each subset the corresponding phase of the respiratory cycle, resulting in a 4D cone-beam CT image. A more advanced solution is motion-compensated cone-beam CT which necessitates an estimate of the respiratory motion during the cone-beam acquisition to compensate for the respiratory motion during the reconstruction from all the cone-beam projection images. This chapter is an overview of these recent developments for correction of respiratory motion in cone-beam CT for image-guided radiotherapy.