Crystalline Exposition During Pediatric Cranial CT Imaging

Study Overview
=================
Brief Summary
-----------------
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

Detailed Description
-----------------
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.

Official Title
-----------------
Crystalline Exposition During Pediatric Cranial CT Imaging

Conditions
-----------------
Any Pathology Requiring a Cranial CT Imaging

Intervention / Treatment
-----------------
* Other: use or non-use of dose modulator and bismuth mask


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Children between 5 and 16 yrs old Indication of cerebral CT with or without contrast regardless to indication or exam specificity Patients beneficiary or affiliated to health system security Oral consent for data processing from the child and his/her representative of parental authority Exclusion Criteria: Children anxious or agitated Sedated patients or patients under general anaesthesia Impossibility to position the skull on the orbito-meatal plane (intubation for example) Patients under legal protection

Ages Eligible for Study
-----------------
Minimum Age: 5 Years
Maximum Age: 16 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| without modification of dose and without bismuth mask<br>The cranial CT imaging presrcibed in usual care will be performed without modification of dose and without bismuth mask | Other: use or non-use of dose modulator and bismuth mask<br>* 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<br>|
| with modification of dose and with bismuth mask<br>e cranial CT imaging presrcibed in usual care will be performed with modification of dose and with bismuth mask | Other: use or non-use of dose modulator and bismuth mask<br>* 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<br>|
| without modification of dose and with bismuth mask<br>e cranial CT imaging presrcibed in usual care will be performed without modification of dose and with bismuth mask | Other: use or non-use of dose modulator and bismuth mask<br>* 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<br>|
| with modification of dose and without bismuth mask<br>e cranial CT imaging presrcibed in usual care will be performed with modification of dose and without bismuth mask | Other: use or non-use of dose modulator and bismuth mask<br>* 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<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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 | Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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 | 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 | Baseline | 
| Image quality | Quantitative analysis of the image quality obtained with both systems after CT acquisition. Quality will be assessed by radiologist's categorization | Baseline | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
dosimetry, Radioprotection, tomodensitometry, pediatrics