Peak skin and eye lens radiation dose from brain perfusion CT based on Monte Carlo simulation

Di Zhang, Chris H. Cagnon, J. Pablo Villablanca, Cynthia H. McCollough, Dianna D. Cody, Donna M. Stevens, Maria Zankl, John J. Demarco, Adam C. Turner, Maryam Khatonabadi, Michael F. McNitt-Gray

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

OBJECTIVE. The purpose of our study was to accurately estimate the radiation dose to skin and the eye lens from clinical CT brain perfusion studies, investigate how well scanner output (expressed as volume CT dose index [CTDI vol]) matches these estimated doses, and investigate the efficacy of eye lens dose reduction techniques. MATERIALS AND METHODS. Peak skin dose and eye lens dose were estimated using Monte Carlo simulation methods on a voxelized patient model and 64-MDCT scanners from four major manufacturers. A range of clinical protocols was evaluated. CTDI vol for each scanner was obtained from the scanner console. Dose reduction to the eye lens was evaluated for various gantry tilt angles as well as scan locations. RESULTS. Peak skin dose and eye lens dose ranged from 81 mGy to 348 mGy, depending on the scanner and protocol used. Peak skin dose and eye lens dose were observed to be 66-79% and 59-63%, respectively, of the CTDI vol values reported by the scanners. The eye lens dose was significantly reduced when the eye lenses were not directly irradiated. CONCLUSION. CTDI vol should not be interpreted as patient dose; this study has shown it to overestimate dose to the skin or eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice. These actions should be considered when they are consistent with the clinical task and patient anatomy.

Original languageEnglish (US)
Pages (from-to)412-417
Number of pages6
JournalAmerican Journal of Roentgenology
Volume198
Issue number2
DOIs
StatePublished - Feb 2012

Keywords

  • CT perfusion
  • Eye lens dose
  • Monte Carlo simulation
  • Radiation dose
  • Skin dose

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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    Zhang, D., Cagnon, C. H., Villablanca, J. P., McCollough, C. H., Cody, D. D., Stevens, D. M., Zankl, M., Demarco, J. J., Turner, A. C., Khatonabadi, M., & McNitt-Gray, M. F. (2012). Peak skin and eye lens radiation dose from brain perfusion CT based on Monte Carlo simulation. American Journal of Roentgenology, 198(2), 412-417. https://doi.org/10.2214/AJR.11.7230