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Correction of megavoltage cone‐beam CT images for dose calculation in the head and neck region

2008; Wiley; Volume: 35; Issue: 3 Linguagem: Inglês

10.1118/1.2839146

2473-4209

Jean‐François Aubry, Jean Pouliot, Luc Beaulieu,

Medical Imaging Techniques and Applications

Megavoltage cone‐beam computed tomography (MVCBCT) imaging systems are now available for image‐guided radiation therapy delivery and verification. In order to use the three‐dimensional anatomical information for dose calculation, the MVCBCT image must provide accurate electron density. This work proposes a new method that has been developed to correct for the cupping and missing data artifacts seen on MVCBCT images of the head and neck region. It uses a conventional kilovoltage CT (kVCT) image as a reference for electron density and rigid registration with a MVCBCT image to obtain correction factors. Dose calculations performed on MVCBCT images corrected with the proposed method agree with calculations done on kVCT images within on phantoms. With patients images the agreement is within above the shoulders and below the shoulder line. This level of dose calculation accuracy allows the use of MVCBCT images for dose verification purposes.