Assessment of a commercially available automatic deformable registration system

B Gino Fallone,D Ryan C Rivest,Albert D Murtha,Terence A Riauka

doi:10.1120/jacmp.v11i3.3175

B Gino Fallone, D Ryan C Rivest + Show 2 more

Open Access

https://doi.org/10.1120/jacmp.v11i3.3175

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Abstract

In recent years, a number of approaches have been applied to the problem of deformable registration validation. However, the challenge of assessing a commercial deformable registration system – in particular, an automatic registration system in which the deformable transformation is not readily accessible – has not been addressed. Using a collection of novel and established methods, we have developed a comprehensive, four‐component protocol for the validation of automatic deformable image registration systems over a range of IGRT applications. The protocol, which was applied to the Reveal‐MVS system, initially consists of a phantom study for determination of the system's general tendencies, while relative comparison of different registration settings is achieved through postregistration similarity measure evaluation. Synthetic transformations and contour‐based metrics are used for absolute verification of the system's intra‐modality and inter‐modality capabilities, respectively. Results suggest that the commercial system is more apt to account for global deformations than local variations when performing deformable image registration. Although the protocol was used to assess the capabilities of the Reveal‐MVS system, it can readily be applied to other commercial systems. The protocol is by no means static or definitive, and can be further expanded to investigate other potential deformable registration applications.PACS numbers: 87.19.xj, 87.56.Da, 87.57.nj

Highlights

In recent years, deformable image registration has become a very important component in a number of image-guided radiation therapy (IGRT) and adaptive radiation therapy (ART) protocols
These and other observations suggest that the commercial system is more apt to account for global deformations than local variations when performing deformable image registration
We have presented a protocol for the validation of automatic commercial deformable image registration systems

Summary

Introduction

Deformable image registration has become a very important component in a number of image-guided radiation therapy (IGRT) and adaptive radiation therapy (ART) protocols. 102 Rivest et al.: Registration system validation to compare algorithms by evaluating similarity measures such as the sum of square intensity differences (SSD), correlation coefficient (CC), and mutual information (MI) upon completion of image registration.[13,15,16,17] It is assumed that there is a direct correlation between enhanced similarity values and registration accuracy. These methods may be sufficient for relative comparison, they provide little information on the absolute accuracy of registration. Authors have argued that phantoms have limited value in validating deformable registration algorithms because they cannot fully assess the impact of anatomical variations on the algorithm’s performance.[24,25]

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