A novel method for spine ultrasound and X-ray radiograph registration

•This work is designed to provide registration for spine ultrasound and X-ray radiograph.•An improved FFD registration method based on mutual registration and hierarchical adaptive grid (MRHA-FFD) is first put forward in this paper.•The registration image quality is improved by introducing a Blur-aware Attention Network (BANet)•The feasibility of the registration for clinical spine imaging is verified through qualitative and quantitative evaluation indicators. Ultrasound is a promising imaging method for scoliosis evaluation because it is radiation free and provide real-time images. However, it cannot provide bony details because ultrasound cannot penetrate the bony structure. Therefore, registration of real-time ultrasound images with the previous X-ray radiograph can help physicians understand the spinal deformity of patients. In this study, an improved free-from deformation registration method based on mutual registration and hierarchical adaptive grid (MRHA-FFD) was developed. The method first performed registration grid preprocessing and then optimized control points and conducted mutual registration. Finally, a Blur-aware Attention Network was adopted for image deblurring. The performance of each step was verified by ablation experiments. Comparison experiment between the proposed method and traditional registration methods was also conducted. The qualitative and quantitative results suggested that MRHA-FFD is a promising approach for registering spine ultrasound image and X-ray radiograph.