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Contact lens-type ocular in vivo dosimeter for radiotherapy

Authors
 Jung-In Kim  ;  Jin-Dong Cho  ;  Jaeman Son  ;  Chang Heon Choi  ;  Hong-Gyun Wu  ;  Jong Min Park 
Citation
 MEDICAL PHYSICS, Vol.47(2) : 722-735, 2020-02 
Journal Title
MEDICAL PHYSICS
ISSN
 0094-2405 
Issue Date
2020-02
MeSH
Calibration ; Contact Lenses* ; Eye / radiation effects* ; Humans ; Optical Phenomena ; Phantoms, Imaging ; Radiometry / instrumentation* ; Radiotherapy*
Keywords
contact lens dosimeter ; lens dose ; ocular dosimeter ; radiation therapy
Abstract
Purpose This study aimed to (a) develop a contact lens-type ocular in vivo dosimeter (CLOD) that can be worn directly on the eye and (b) assess its dosimetric characteristics and biological stability for radiation therapy. Methods The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation-sensitive component - an active layer similar to a radiochromic film - to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients. Results The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. The responses obtained for the 10 and 15 MV photon beams were 1.7% and 1.9% higher compared to the 6 MV photon beam. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90 degrees to 180 degrees with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. For a dose range of 0 to 50 cGy, the total uncertainties for 5, 10, and 50 cGy were 14.2%, 8.9%, and 5%, respectively. Quantitative evaluation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed. Conclusions The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device. The evaluation of dose characteristics in open field conditions shows that the CLOD can be applied to an in vivo dosimeter in radiotherapy.
Full Text
https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.13932
DOI
10.1002/mp.13932
Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Radiation Oncology (방사선종양학교실) > 1. Journal Papers
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/190240
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