Comparison of three dosimetric techniques to take in account lung tumor motion: Gating-like technique results lead to advice the use of gating device even in the cases of pre-operative irradiation
Fiche publication
Date publication
janvier 2010
Auteurs
Membres identifiés du Cancéropôle Est :
Pr NOEL Georges
Tous les auteurs :
Beneyton V, Billaud G, Niederst C, Meyer P, Bourhala K, Schumacher C, Karamanoukian D, Noel G
Lien Pubmed
Résumé
Purpose. - Comparison of three dosimetric techniques of lung tumor delineation to integrate tumor motion during breathing. Patients and methods. - Nineteen patients with T1-3NOMO malignant lung tumor were treated with definitive chemoradiotherapy (14 cases) or pre-surgery chemoradiation. Doses were, respectively, 66 and 46Gy. CT-scan for delineation was performed during three phases of breathing: free breathing and deep breath-hold inspiration and expiration. GTV (gross tumor volume) was delineated on the three sequences. The classic technique included GTV from the free-breathing sequence plus a CTV (clinical target Volume) margin of 5 to 8 mm plus a PTV (planning target volume) margin of 7 to 10 mm (including ITV internal tat-get volume] margin and set-up margin). The gating-like technique included GTV from the deep breath-hold inspiration sequence Plus a CTV margin of 5 to 8 mm plus a PTV margin of 2 min. The three-volume technique, included GTV as a result of the fusion of GTVs from the three sequences plus a CTV margin of 5 to 8 min plus a PTV margin of 2 mm. Dosimetry Was Calculated for the three PTVs, if possible, with the same fields number and position. Dose constraints and rules were imposed to accept dosimetries: firstly spinal cord maximal dose less than 45 Gy, followed by V95% for PTV greater than or equal to 95%, and V20 GY(Gy) for lung less than or equal to 30%, V30 GY(Gy) for lung less than or equal to 20%. Results. - GTVs were not statistically different between the three methods of delineation. PTVs were significantly lower with the gating-like technique. V95% of the PTV were not different between the three techniques. With the classic-, the gating-like- and the 3-volume techniques, dosimetry was considered as acceptable, respectively in 15, 18 and 15 cases. Comparisons of constraint values showed that the gating-like method gave the best results. In the case of pre-operative management, the gating-like method allowed the best results even for the V95% Values. However, in the absence of gating device or without the Possibility to use it, the 3-volume method allowed to take into account More precisely the organ motion than the classical technique. Conclusion. - The 3-volume method can be done. It is good method to take into account the organ motions. However, the gating-like method gives the best results leading to propose its use even for pre-operative patients With Upper tumors. (D 2009 Published by Elsevier Masson SAS on behalf of the Societie francaise de radiotherapie oncologique (SFRO).
Référence
Cancer Radiother. 2010 Jan;14(1):50-8