A dosimetric comparative study following RTOG and ESTRO contouring guidelines for breast radiation therapy

To compare the dosimetric parameters considering the Radiation Therapy Oncology Group (RTOG) and European Society for Radiotherapy and Oncology (ESTRO) guidelines for breast cancer radiotherapy. Two radiotherapy techniques, intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT), were considered. Twenty-eight patients with left-sided medially-located TanyN2M0 tumors were contoured based on RTOG and ESTRO guidelines. 9-field IMRT, 10-field IMRT, 11-field IMRT, and VMAT treatment plans were applied as radiotherapy (RT) techniques for both contouring sets. The dosimetric parameters of the RT plans were extracted and compared. Comparing dose-volume histogram (DVH) parameters, equivalent uniform dose (EUD), and normal tissue complication probability (NTCP) of OARs across the contouring guidelines and considering each RT technique showed that the only significant differences were higher Dmax, Dmean, V30, and V45, EUD, and NTCP of the thyroid in all treatment modalities when the RTOG guideline had been adopted. Using the VMAT technique, PTV's EUD and the tumor control probability (TCP) were considerably higher when the ESTRO guideline was adopted. Moreover, the conformity index (CI) of VMAT plans was significantly higher when the ESTRO guideline was used. Unless having higher doses to thyroid when the RTOG guideline was adopted, the doses to other organs-at-risk (OAR) were similar between the two considering guidelines. Moreover, except for higher EUD, TCP, and CI for VMAT when the ESTRO guideline was used, no other significant differences were obtained between dosimetric parameters of target volumes considering the RT techniques and contouring guidelines. Comparer les paramètres dosimétriques en utilisant les recommandations de délinéation mammaire selon le Radiation Therapy Oncology Group (RTOG) et de la Société européenne de radiothérapie et d’oncologie (ESTRO). Deux techniques de radiothérapie ont été comparées : radiothérapie conformationnelle avec modulation d’intensité (RCMI) et arcthérapie volumétrique avec modulation d’intensité (AVMI). Vingt-huit patients atteints de tumeurs T (quel que soit) N2M0 médiales du côté gauche ont été inclus dans l’étude. Les délinéations ont été réalisées selon les recommandations de l’ESTRO ou du RTOG. Les plans de tRCMI ont comporté 9 faisceaux, 10 faisceaux et 11 faisceaux et ont été comparés au plans de AVMI. La comparaison des paramètres de l’histogramme dose-volume (DVH), de la dose uni