Operator’s eye lens dose in computed tomography–guided interventions

OBJECTIVES: To survey (1) operator’s eye lens doses in typical computed tomography (CT)-guided interventions, (2) correlation between dose length product (DLP) and the operator’s dose, and (3) different ways for estimating the eye lens dose in clinical settings. METHODS: Doses of 16 radiologists in 164 CT-guided interventional procedures were prospectively measured during a 6-month time period upon radioprotective garments and descriptive statistical outcomes were calculated. The correlations between DLP and measured doses were surveyed. RESULTS: On average, the operator’s dose at the eye level (DEL, H(p)(0.07)) was 22 μSv per procedure and the personal equivalent dose H(p)(10) at the collar level was 21 μSv per procedure. The mean DLP of a procedure was 320 mGy cm, where 54% resulted from the fluoroscopy, the mean exposure time being 18 s. Based on the results, the operator’s DEL could be estimated from DLP using the equation DEL (μSv) = 0.10 μSv/mGy cm × patient fluoro DLP (mGycm) (p < 0.001), and the dose at the collar level (DCL) using the equation DCL (μSv) = 0.12 μSv/mGy cm × patient fluoro DLP (mGy cm) (p < 0.001). In addition, DEL (μSv) = 0.7 × DCL (μSv). CONCLUSIONS: The eye lens doses in CT-guided interventions are generally low even without protective equipment, and it is unlikely that the recommended annual equivalent dose limit of 20 mSv for the lens of the eye will be exceeded by conducting CT-guided interventions solely. Eye lens dose can be roughly estimated based on either DLP of the procedure or dose measured at the operator’s collar level. KEY POINTS: • Eye lens doses in CT-guided operations are generally low. • It is unlikely that the ICRP recommendation of the yearly equivalent dose limit of 20 mSv will be exceeded by conducting CT-guided interventions solely. • Magnitude of eye lens dose can be estimated based on either DLP of the procedure or dose measured at the operator’s collar level.