PURPOSE: To quantify the impact of systematic use of tube current modulation for neuroradiology CT protocols in terms of patient dose reduction and image quality.
METHOD AND MATERIALS: As part of a retrospective study, approved by our institutional review board and in compliance with Health Insurance Portability and Accountability Act (HIPAA), we evaluated the impact of dose modulation on 4 types of neuroradiological CT studies: brain noncontrast CT (NCT) in adult patients, brain NCT in pediatric patients, adult cervical spine CT, and adult cervical and intracranial CT-angiogram (CTA). For each type of CT study, three series of 100 consecutive studies were reviewed: (1) 100 studies without dose-modulation; (2) 100 studies with Z-axis dose-modulation; (3) 100 studies with XYZ-axis dose-modulation. For each examination, the weighted computed dose tomographic index (CTDIvol) and dose length product (DLP) were recorded, and noise was measured. Each examination was reviewed by a neuroradiologist blinded to the dose modulation mode for image quality. Continuous variables (CTDIvol, DLP, noise) were compared using T-tests, and categorical variables (image quality) using Chi2 tests.
RESULTS: For adult brain NCT, CTDIvol and DLP were reduced by 60.0% and 60.3%, respectively, using Z-axis dose-modulation; and by 50.4% and 22.4%, respectively, using XYZ-axis dose-modulation. Significant dose reductions were also observed for pediatric brain NCT, cervical spine CT and CTAs. Image quality and noise were unaffected by use of dose modulation.
CONCLUSION: Dose-modulation techniques should be systematically used for neuroradiology CT examinations, because they afford significant dose reduction, while image quality is maintained.
CLINICAL RELEVANCE/APPLICATION: Utilization of dose modulation techniques results in significant reduction in radiation dose to patients for studies typically utilized in a neuroradiology department without loss of image quality.