Journal of Hong Kong College of Radiologists

Volume 4 Number 3, 2001

Lens Exclusion in Computed Tomography Scans of the Brain - The Local Practice

KF Lai,1 YK Cheung,1 CB Tan,2 E Tsui,1 SK Yu3
1Department of Diagnostic Radiology, Tuen Mun Hospital, Hong Kong, 2Department of Diagnostic Radiology, Kwong Wah Hospital, Hong Kong, 3Medical Physics Division, Tuen Mun Hospital, Hong Kong

Objectives: To review protocols used in Hong Kong public hospitals for computed tomography brain scans, with a view to highlighting potential radiation damage to the lens with particular scanning planes. Methods: Following a survey of radiological practice in 8 local hospitals, a retrospective study of routine computed tomography brain scanning, with special interest in avoidance of lens exposure, was completed in 2 major regional hospitals. Six hundred patient records were reviewed, along with the scanning protocols used. Results: The orbitomeatal plane was the predominant reference plane utilised by the majority of public hospitals in this locality, including the 2 hospitals investigated in depth. More than 90% of patients in the study population were found to have either one or both lenses irradiated, despite differences in machines and staff. Conclusion: A protocol for computed tomography brain scanning, specifying a baseline orientation which excludes the lens, should be established in hospitals to prevent routine lens irradiation. (J HK Coll Radiol 2001;4:181-184)

Key words : Computed tomography brain, Lens dose, Radiation protection

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