Gold coated contact lens-type ocular in vivo dosimeter (CLOD) for monitoring of low dose in computed tomography: A Monte Carlo study. (December 2021)

• Record Type: Journal Article
• Authors: Jung, Seongmoon; Kim, Jung-in; Park, Jong Min; Wu, Hong-Gyun; Choi, Chang Heon
• Is Part Of: Physica medica. Volume 92(2021)
• Page Start: 1
• Page End: 7
• Publication Date: 2021-12
• Subjects: Contact lens dosimeter -- Lens dose -- Dose enhancement -- Monte Carlo simulation -- Gold nanoparticle; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2021.10.016
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: This study reports a sensitivity enhancement of Au-coated lens-type dosimeter. A layer of Au was attached to the upstream of lens-type dosimeter. The dose enhancement factor of 5- μ m thick gold layers was 5.4 for 120 kVp X-ray tube. Au-coated CLODs can measure a few cGy dose delivered to patients during CT imaging. Abstract: Purpose: This study reports a sensitivity enhancement of gold-coated contact lens-type ocular in vivo dosimeters ( CLOD s) for low-dose measurements in computed tomography (CT). Methods: Monte Carlo (MC) simulations were conducted to evaluate the dose enhancement from the gold (Au) layers on the CLOD s. The human eye and CLOD s were modeled, and the X-ray tube voltages were defined as 80, 120, and 140 kVp. The thickness of the Au layer attached to a CLOD ranged from 100 nm to 10 μm. The thickness of the active layer ranged from 20 to 140 μm. The dose ratio between the active layer of the Au-coated CLOD and a CLOD without a layer, i.e., the dose enhancement factor (DEF), was calculated. Results: The DEFs of the first 20-μm thick active layer of the 5-μm thick Au-coated CLOD were 18.4, 19.7, 20.2 at 80, 120, and 140 kVp, respectively. The DEFs decreased as the thickness of the active layer increased. The DEFs of 100-nm to 5-μm thick Au layers increased from 1.7 to 5.4 for 120-kVp X-ray tube voltage when the thickness of the active layer was 140 μm. Conclusions: The MC results presented a higher sensitivity of Au-coated CLODs (∼20-times higher than that of CLODs without a gold layer). Au-coated CLODs can be applied to an evaluation of very low doses (a few cGy) delivered to patients during CT imaging.