The study is going to enroll about 220 consecutive patients with screws in lumber spine after internal fixation surgery who underwent follow-up assessment using Incisive CT according to the department standard of care. Retrospective data sets will be reconstructed into conventional image, the O-MAR algorithm, and Precise-MAR. Three blinded, independent radiologists evaluate both qualitative and quantitative analysis of image quality of surrounding tissue and artifact. Statistical analysis included the Friedman test, Wilcoxon signed-rank test, and Levene test.

Inclusion Criteria:

1. Images come from patients aged ≥ 18 years,
2. Images come from patients with screws in lumber spine after internal fixation surgery underwent follow up Incisive CT scan;
3. Images come from patients who comply with the requirements of informed consent at the study site.

Exclusion Criteria:

1. Patients with other metal objects inside or outside the body
2. There is movement during the CT scan, causing by breathing etc. artifact affecting image quality
3. Data is considered unsuitable for enrollment based on the investigator's evaluation due to incomplete clinical data or radiological information etc.

The study participants from Beijing Jishuitan Hospital.