Lens exposure during brain scans using multidetector row CT scanners: methods for estimation of lens dose

Area of Science:

• Radiological physics
• Medical imaging
• Radiation protection

Background:

• Recent studies suggest lower radiation dose thresholds for lens injuries than current guidelines.
• Accurate assessment of radiation dose to the lens is crucial for patient safety.

Purpose of the Study:

• To measure radiation dose to the lens during brain CT scans using multidetector row CT.
• To evaluate methods for estimating lens dose during these procedures.

Main Methods:

• Utilized 8 types of multidetector row CT scanners with a human-shaped phantom.
• Measured lens doses using an optically stimulated luminescence dosimeter (OSLD) during whole-brain scans including the orbit.
• Assessed the impact of different scan starting points (inferior orbital rim, orbitomeatal line, superior orbital rim) on lens dose.

Main Results:

• Lens doses ranged from 42.6 to 103.5 mGy during whole-brain CT scans including the orbit.
• Ratios of lens dose to CTDIvol (Computed Tomography Dose Index volume) were between 80.6% and 103.4%.
• Setting scan starting points more superiorly significantly reduced lens doses (11.8%-20.9% of doses from inferior orbital rim).

Conclusions:

• CTDIvol is a reliable indicator for estimating lens dose in brain CT scans that include the orbit.
• Optimizing scan starting points can effectively minimize radiation exposure to the lens.