Fig 7.

Sample images from a 2010 study with aggressive dose reduction during a technically successful CT-guided right C6 selective nerve root block. Only the survey CT images were acquired helically (scan length = 50 mm). The milliampere/DLP (milligrays per centimeter) was 29/20.1, 10/0.5, and 20/1.0 for the survey (A), guide (B), and contrast (C) images, respectively (note, 8 guide series with slightly varying milliamperes or ranges were obtained). Total examination DLP was 28.6 mGy · cm, giving an estimated total effective dose of only 0.17 mSv. This dose is comparable with or lower than that for fluoroscopy-based spinal injections for pain.