| Chen Cheng,Bao Zhirong,Yu Haijun,Liu Hui.Improved 2D image registration algorithm applied to head and neck tumor[J].Chinese Journal of Radiological Medicine and Protection,2017,37(9):690-695 |
| Improved 2D image registration algorithm applied to head and neck tumor |
| Received:February 09, 2017 |
| DOI：10.3760/cma.j.issn.0254-5098.2017.09.010 |
| KeyWords:Setup errors Electronic portal imaging device Portal image Image registration |
| FundProject: |
| Author Name | Affiliation | E-mail | | Chen Cheng | Department of Radiation Oncology and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China | | | Bao Zhirong | Department of Radiation Oncology and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China | | | Yu Haijun | Department of Radiation Oncology and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China | | | Liu Hui | Department of Radiation Oncology and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China | liuhui69@hotmail.com |
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| Abstract:: |
| Objective To evaluate the effect of setup errors on the 2D image projection and image registration, and then propose an improved registration method based on mutual information.Methods An anthropomorphic head phantom was used to simulate the rotational and translational setup errors. The geometric disparities were reflected by the changes of mutual information. Known setup errors were intentionally introduced to twenty cases divided into two groups demarcated by 3 mm translation error and 3° rotation error: ten cases with larger errors and ten with smaller errors. Then the anterior-posterior and lateral portal images were captured by the electronic portal imaging device (EPID), based on which the setup errors were calculated using two mutual information registration method respectively: the vender provided one, and the improved method as proposed. The calculated errors were compared with the actual setup errors to evaluate robustness of the method.Results For the ten cases with smaller setup errors, the average translational registration disparities using the conventional method were 0.3, 0.4, and 0.3 mm in x, y and z directions respectively. The rotational disagreements were 0.4° in both x and z directions. The average time consumption was 28.7 s. The corresponding discrepancies analyzed using the improved method were 0.3, 0.4, 0.3 mm, 0.5° and 0.4°, respectively. On average, 31.1 s was needed for registration. For the ten cases with larger setup errors, the mean disparities of the conventional method were 0.9, 0.7, 0.8 mm, 0.9° and 0.8°, 29.9 s taken on average. The corresponding result of the improved method was 0.5, 0.4, 0.5 mm, 0.6° and 0.5°, 33.2 s taken on average.Conclusions Regarding smaller setup errors, the two methods showed little difference and both had good performance in image registration accuracy. For larger setup errors, however, the improved mutual information registration method exhibited significantly higher accuracy than the conventional method, at cost of clinically acceptable registration time. |
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