Study design:

Retrospective cross-sectional study.

Objective:

(1) To determine the incremental increase in intraoperative ionizing radiation conferred by CT as compared to conventional radiography; and (2) To model different lifetime cancer risks contextualized by the intersection between age, sex, and intraoperative imaging modality.

Summary of background data:

Emerging technologies in spine surgery like navigation, automation, and augmented reality commonly utilize intraoperative CT. While much has been written about the benefits of such imaging modalities, the inherent risk profile of increasing intraoperative CT has not been well evaluated.

Methods:

Effective doses of intraoperative ionizing radiation were extracted from 610 adult patients who underwent single-level instrumented fusion for lumbar degenerative or isthmic spondylolisthesis from January 2015 through January 2022. Patients were divided into those who received intraoperative CT (n=138) and those who underwent conventional intraoperative radiography (n=472). Generalized linear modeling was utilized with intraoperative CT use as a primary predictor and patient demographics, disease characteristics, and preference-sensitive intraoperative considerations (e.g. surgical approach, surgical invasiveness) as covariates. The adjusted risk difference in radiation dose calculated from our regression analysis was used to prognosticate the associated cancer risk across age and sex strata.

Results:

(1) After adjusting for covariates, intraoperative CT was associated with 7.6 mSv (IQR 6.8-8.4 mSv; P<0.001) more radiation than conventional radiography. (2) For the median patient in our population (a 62-year-old female), intraoperative CT use increased lifetime cancer risk by 2.3 incidents (IQR 2.1-2.6) per 10,000. Similar projections for other age and sex strata were also appreciated.

Conclusion:

Intraoperative CT use significantly increased cancer risk compared to conventional intraoperative radiography for patients undergoing lumbar spinal fusions. As emerging technologies in spine surgery continue to proliferate and leverage intraoperative CT for cross-sectional imaging data, strategies must be developed by surgeons, institutions, and medical technology companies to mitigate long-term cancer risks.