Advanced

AJNR - American Journal of Neuroradiology

Published ahead of print on October 14, 2008
doi: 10.3174/ajnr.A1327

This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: ajnr.A1327v1 30/2/373    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Tan, J.S.P. Articles by Chan, L.-L. Search for Related Content PubMed PubMed Citation Articles by Tan, J.S.P. Articles by Chan, L.-L.

American Journal of Neuroradiology 30:373-377, February 2009
© 2009 American Society of Neuroradiology

BRAIN

Comparison of Eye Lens Dose on Neuroimaging Protocols between 16- and 64-Section Multidetector CT: Achieving the Lowest Possible Dose

J.S.P. Tan^a, K.-L. Tan^a, J.C.L. Lee^c, C.-M. Wan^a, J.-L. Leong^b and L.-L. Chan^a

^a Department of Diagnostic Radiology, Singapore General Hospital, Singapore
^b Department of Otolaryngology, Singapore General Hospital, Singapore
^c Department of Radiation Oncology, National Cancer Centre, Singapore

Please address correspondence to Judy S.P. Tan, MD, Singapore General Hospital, Outram Rd, Singapore 169608; e-mail: judy.tan.s.p{at}sgh.com.sg

BACKGROUND AND PURPOSE: To our knowledge, there has been no study that compares the radiation dose delivered to the eye lens by 16- and 64-section multidetector CT (MDCT) for standard clinical neuroimaging protocols. Our aim was to assess radiation-dose differences between 16- and 64-section MDCT from the same manufacturer, by using near-identical neuroimaging protocols.

MATERIALS AND METHODS: Three cadaveric heads were scanned on 16- and 64-section MDCT by using standard neuroimaging CT protocols. Eye lens dose was measured by using thermoluminescent dosimeters (TLD), and each scanning was repeated to reduce random error. The dose-length product, volume CT dose index (CTDI_vol), and TLD readings for each imaging protocol were averaged and compared between scanners and protocols, by using the paired Student t test. Statistical significance was defined at P < .05.

RESULTS: The radiation dose delivered and eye lens doses were lower by 28.1%–45.7% (P < .000) on the 64-section MDCT for near-identical imaging protocols. On the 16-section MDCT, lens dose reduction was greatest (81.1%) on a tilted axial mode, compared with a nontilted helical mode for CT brain scans. Among the protocols studied, CT of the temporal bone delivered the greatest radiation dose to the eye lens.

CONCLUSIONS: Eye lens radiation doses delivered by the 64-section MDCT are significantly lower, partly due to improvements in automatic tube current modulation technology. However, where applicable, protection of the eyes from the radiation beam by either repositioning the head or tilting the gantry remains the best way to reduce eye lens dose.