Quantitative evaluation of deformable image registration based on TG- 132

Abstract

Author(s): T. Ragul, V. Sharma, PV. Nameer, SK Senthil Kumar, Sumanta Manna, Sharad Singh, Pramod Kumar Gupta, Shaleen Kumar, K J Maria Das

Aim: This study aimed to evaluate the Deformable Image Registration (DIR) software of Mirada® and Velocity® using quantitative measures as per the recommendation based on Task Group TG- 132.

Materials and Methods: Task Group 132 has provided geometric and anatomic virtual phantoms for quality assurance which were imported and contoured on the reference image, followed by DIR and then the contours were propagated on all the CT/CBCT data sets with different offsets and orientation of geometric and anatomic virtual phantom using Mirada and Velocity. Analysis was performed using the Dice Similarity Coefficient (DSC), Mean Distance to Agreement (MDA), Housdorff (HD) and Target Registration Error (TRE). The results were compared to find the difference in significance using a Paired t-test with a significance level set at 5%.

Results: The obtained statistical result is listed below, considering the Geometric phantom, with regards to DSC, Mean and SD values obtained for Mirada and Velocity is 0.955 ± 0.348 and 0.965 ± 0.418 respectively with the p-value coming at 0.013 indicating a significant difference. Considering MDA, a significant difference of p-value of 0.001 was found between Mirada and Velocity with the former having 0.668 ± 0.684 compared to 0.381 ± 0.424 of the latter. For HD, Mirada obtained a mean value of 3.464 ± 2.091 in comparison with 2.202 ± 1.215 of Velocity. As for TRE, three fiducials within the phantom were considered and Mirada had a mean value of 1.037 mm while Velocity had 1.338 mm. While analyzing the Anatomic phantom, DSC values for Mirada and Velocity were 0.946 ± 0.031 and 0.944 ± 0.313 respectively indicating no significance. Likewise, no significance was found considering MDA (Mirada: 0.435 ± 0.235, Velocity: 0.449 ± 0.242). Regarding HD, Mirada obtained 4.216 mm while Velocity had 4.233 mm showing exceptional compliance. The mean value of TRE for three fiducials was found to be less than 1 mm it’s also found significant difference.

Conclusion: This study highlights the strengths and differences between Mirada and Velocity in DIR for adaptive radiotherapy. While both software applications excel in DSC, MDA and HD, the observed difference in TRE indicates a potential advantage of Mirada in achieving better image registration, especially in landmark-based registration scenarios.

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