This study focuses on reduction of X-rays dose applied to eye's lens during cranial CT in children. Principal objective is to analyse the efficiency of ocular bismuth masks, which are associated with an eye's lens dose modulation
Eye's lens radiosensitivity represents an important subject of investigation in radiology. Indeed, eye's lens is recognised as one of the most radiosensitive organs in human body.\[1,2\] Radiation induced cataracts represent a determining effect of ionising radiations and has been widely studied. "International Commission for Radiological Protection" has evaluated cataract appearance threshold at 15 Gy in 1977 ",\[3\] then at 8 Gy \[4\] and 5 Gy in 2007.\[5\] Finally, in 2011 new studies gave rise to a new limit of appearance of 0.5 Gy. Eye's lens radiosensitivity seems to have been underestimated for several years and so there is a significant improvement to be made in radioprotection in order to protect to the best of the investigator's ability both patient and manipulator. This was also confirmed by the Directive EURATOM 2013/59 (which is in the process of being transposed in French legislation)\[6\] that reduces legal limit dose delivered to eye's lens from 150mSv to20mSv, for categories A workers. This study is performed on 4 sequential groups, of ten patients, whereby one control group without ocular protection added. Other groups benefit either from a bismuth ocular protection, from a dose modulation applied to the eye's lens, or from both techniques associated. For each group, experiment is then focused on dose received by the eye's lens (measured using TLD detectors) as well as on Image quality obtained. Currently, there is no recommendation regarding lens protection for patient who benefit of a head tomodensitometry. Some practices are already used routinely but without a critical analysis of a comparison of their respective benefits.
Study Type
OBSERVATIONAL
Enrollment
23
For each child for who the eligibility criteria are met, the CT exam is perfomed with or without dose modulator associated to with or without bismuth mask
CHU Bordeaux
Bordeaux, France
Efficiency of a bismuth based ocular protection associated with eye's lens dose modulation technique
quantification of the efficiency of a bismuth based ocular protection associated with eye's lens dose modulation technique during cranial CT of children. This will be measured by the average dose difference relative to the number of helices, kV and mAs delivered between groups 1 and 2
Time frame: Baseline
Efficiency of a bismuth based ocular protection
Quantification of the efficiency of a bismuth based ocular protection during CT acquisition. This will be measured by the average dose difference relative to the number of helices, kV and mAs delivered between groups 1 and 3
Time frame: Baseline
Efficiency of eye's lens dose modification
Quantification of the efficiency of eye's lens dose modification technique during CT acquisition. This will be measured by the average dose difference relative to the number of helices, kV and mAs delivered between groups 1 and 4
Time frame: Baseline
Image quality
Quantitative analysis of the image quality obtained with both systems after CT acquisition. Quality will be assessed by radiologist's categorization
Time frame: Baseline
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