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2. Irradiation des cristallins des patients par scanners de perfusion itératifs : Dosimétrie et optimisation

Author

Guersen, J., Cassagnes, L., Méchin, G., Etard, C., Rehel, J.-L., Jean, B., Chabert, E., Gabrillargues, J., Labattu, M., Boyer, L., Chabrot, P., CHU Clermont-Ferrand, Image Science for Interventional Techniques (ISIT), Université d'Auvergne - Clermont-Ferrand I (UdA)-Clermont Université-Centre National de la Recherche Scientifique (CNRS), Unité d'Expertise en radioprotection Médicale (IRSN/PRP-HOM/SER/UEM), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Institut Pascal (IP), SIGMA Clermont (SIGMA Clermont)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), PRP-HOM/SER/UEM, and Radiation Protection and Nuclear Safety Institute

Subjects
[SDV]Life Sciences [q-bio], ComputingMilieux_MISCELLANEOUS
Abstract

National audience; The lens of the eye is a radiosensitive organ. In April 2011, the International Commission on Radiological Protection (ICRP) set the new threshold dose of occurrence of deterministic lens effects to 500 mGy. Patients with a ruptured intracranial aneurysm are imaged by CT scans of the brain (CT), for diagnosis and post-treatment follow-up; embolization is the standard treatment. These iterative examinations expose the lens to X-rays. This paper evaluates the lens X-ray exposure of 18 patients who underwent encephalic CT scans after a ruptured intracranial aneurysm in 2011, and proposes a method to reduce this exposure. In our study, 44% of patients received eye doses greater than 500 mGy, generated by CT examinations, especially cerebral CT perfusion, necessary to assess the risk of delayed vasospasm/ischemia. By positioning the patient in neck hyperflexion for cerebral CT perfusion, the dose could be reduced by around 50%. © EDP Sciences, 2014.; Le cristallin est un organe radiosensible. En avril 2011, la Commission Internationale de Protection Radiologique (CIPR) fixait à 500 mGy la nouvelle dose seuil d’apparition d’effets déterministes au cristallin. Les patients qui présentent un anévrysme intracérébral rompu bénéficient d’examens scanographiques de l’encéphale (CT) justifiés, pour le diagnostic et le suivi post traitement, réalisé le plus souvent par embolisation radioguidée. Ces examens itératifs exposent le cristallin aux rayons X. Cet article chiffre l’exposition des cristallins de 18 patients ayant bénéficié en 2011 d’examens scanographiques encéphaliques suite à une rupture d’anévrysme intracérébral, et propose un moyen de diminuer cette exposition. Dans notre étude, 44 % des patients étudiés ont reçu une dose supérieure à 500 mGy au niveau des yeux, générée par les examens scanographiques et en particulier les CT de perfusion, indispensables pour évaluer le risque d’ischémie retardée par vasospasme. Nous avons observé qu’en positionnant les patients en hyper flexion cervicale lors de la réalisation des scanners de perfusion, la dose aux cristallins pouvait être diminuée de près de 50 %.

Published
2014

6. Évaluation de la dose à la peau en radiologie interventionnelle par l'utilisation de films radiochromiques.

Author

LABATTU, M., GUERSEN, J., CHASSIN, V., CASSAGNES, L., MAGNIER, F., DONNARIEIX, D., BOYER, L., and CHABROT, P.

Subjects
*INTERVENTIONAL radiology, *RADIATION doses, *SKIN diseases, *RADIATION dosimetry, *FOLLOW-up studies (Medicine), *DERMATOLOGY, *X-rays
Abstract

Assessment of skin dose in interventional radiology using radiochromic films. The 97/43 /EURATOM Directive (June 30, 1997) indicates interventional radiology as a special practice (Article 9) able to deliver high doses, which is why having safety equipment and procedures, and appropriate quality assurance programs and training is essential. Indeed, using low-energy X-rays during procedures, ranging from a few seconds to several hours (complex cases), inevitably involves stochastic and deterministic risks. The evaluation of the maximum skin dose is useful data in the dermatological follow-up of the patient. In this study, we chose to use Gafchromic® XR-RV3 radiochromic film as a detector to obtain a mapping of the skin dose received by the patient during a procedure. Radiochromic films are interesting because they allow one both to visualize and to quantify the region of the maximum dose. We present the preliminary stages of using the films on patients, that is to say, the study of physical characteristics, the dose calibration, the reading by flatbed scanner and the utilization of films with the image processing software ImageJ. The results show that the use of radiochromic films is relevant to a patient dosimetry assessment. Specifically, the films' response differs by less than 3.6% between calibration at 80 and 120 kV and the overall uncertainty remains below 20% up to a dose of 12 Gy. The evolving response of the films in time being negligible, the reading can be done immediately and utilizing the film requires less than 15 minutes to obtain the dose mapping. The application of this measurement technique in vivo for 58 procedures showed a maximum skin dose that exceeded 3 Gy for 12 patients. These patients were then sent to a dermatological follow-up. Among the 58 patients, assessment of the skin dose with the dosimetry indicators provided by the facilities would have led to the follow-up care of only 4 patients. [ABSTRACT FROM AUTHOR]

Published
2013
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