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Titre : | Impact du produit de contraste et de l'algorithme de calcul dans le calcul de la dose chez les patients irradiés pour tumeur tête et cou |
Auteurs : | Zéphyrin Bizimana, Auteur ; F. Sergent, Promoteur |
Type de document : | Travail de fin d'études |
Année de publication : | 2017 |
Langues: | Français |
Index. décimale : | TFE - Imagerie médicale |
Résumé : |
Background: In the Radiation Therapy treatment procedures, Computed Tomography (CT) simulation is a decisive step. This step allows the determination of the best treatment position of the patient, which offers both comfort and good results. Then, 3D CT-images are acquired. The Injection of the iodine-based Contrast Agent (CA) during CT imaging increases the enhancement of different tissues. Tissues attenuation increases as a result of the high atomic number (Z) of the iodine element. Thus, X-rays are attenuated by the CA uptake, which brings to high Hounsfield Units (HU) inside enhanced tissues. The accuracy of delineating of various organs and volumes increases.
In the treatment planning system, a dose calculation algorithm, which is based on UH, is used. Though, the CA is actually absent when the patient is being treated, whereas, the CA is used in dose calculation with 3D images acquired in CT-Simulation imaging. The increase of the HU in tissues due to the increased CA uptake may affect dose calculation. This work comes to verify the influence of the CA on the final dosimetric calculation that provides treatment to the patient. Methods : A statistical analysis of 18 head and neck cancer patients has been realised in this prospective survey. For each patient, 2 CT (a CT without CA followed by a CT with CA) were performed. The treatment plan was calculated, as usual, on CT-images with CA and was carried-over to the CT-images without CA. After the calculation, the resulting Dose Volume Histogram (DVH) of each CT was established and analysed. In addition, the DVH were studied and compared with defined criteria such as the mean dose and the maximum dose. Some structures have been involved. In order to see the variation of the dose deviations, CT without CA were taken as a reference. Results : For all the criteria, results show that the average of differences between the two CT imaging varies between [-0.5% ; +0.5%], then, close to 0%. This may be the result of small variations in doses calculation resulting from the CA uptake. But also, there may be anatomical variations due to patient movements between the two operated CT imaging. Conclusion: This study concludes that CA injection in the Radiation Therapy treatment planning does not clinically cause a significant difference in the dose calculation. |
Disponible en ligne : | Non |
Lieu du stage : | Centre hospitalier universitaire UCL Namur |
Département : | Imagerie médicale |
Exemplaires (1)
Cote | Support | Localisation | Section | Disponibilité |
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BIZ 17 | Travail de fin d'études | Woluwe | Espace livres | Prêt autorisé Disponible |