Dosimetric prospective study comparing 2D and 3D planning for irradiation of supraclavicular and infraclavicular regions in breast cancer patients.

Purpose: The purpose of this study is to compare 2D plan and 3D plan regarding coverage of the target (supraclavicular and infraclavicular regions) and dose reaching the risk organs (using mean DVH). Depending on the results of this study, modifications can be made to the 2D conventional planning of supraclavicular and infraclavicular regions in order to achieve better coverage of the target tissues.

Materials And Methods: This is a dosimetric study carried out at the radiation oncology department in NCI-Cairo University in the period from January 2012 to October 2012, on 15 patients with breast cancer who are eligible for supraclavicular and infraclavicular irradiation. For All patients, a 2D and a 3D plan were done.

Results: We found that the coverage of the supraclavicular and infraclavicular regions and the chest wall or breast together with levels I and II axilla (PTV) were significantly better with the 3D technique with less over dose than the 2D technique. That difference was highly significant and was most evident in MRM cases. Also we found that organs at risk received a dose in the 3D technique that was more than that received in the 2D technique, again that difference was highly significant and was also most evident in MRM cases but all doses were still within tolerance.

Conclusions: From the present study we concluded that the coverage of the supraclavicular and infraclavicular PTV is significantly worse with the 2D technique using a single oblique field at a fixed depth of 3 cm for all patients despite their different builts.