Radiobiological comparison of 3D conformal and intensity modulated radiation therapy in thetreatment of left-sided breast cancer

The current study aimed to compare the tumor controlprobability (tcp) and normal tissue complication probability (ntcp) of threedimensionalconformal radiation therapy (3d-crt) and intensity-modulatedradiation therapy (imrt) for left-sided breast cancer using radiobiologicalmodels. methods: this study was conducted on 30 patients with left-sidedbreast cancer, who were planned for 3d-crt and 6-9 fields imrt treatmentsusing the prowess treatment planning system. the planning target volume(ptv) dose of 50 gy was administered for the 3d-crt and imrt plans,respectively. the niemierko’s equivalent uniform dose (eud) model wasutilized for the estimation of tumor control probability (tcp) and normaltissue complication probability (ntcp). results: according to the results, themean tcp values for 3d-crt, 6-fields imrt, and 9-fields imrt plans were99.07 ±0.07, 99.24 ±0.05 and 99.28 ±0.04, respectively, showing nostatistically significant difference. the ntcps of the lung and heart wereconsiderably lower in the imrt plans, compared to those in the 3d-crt plans.conclusions: from the radiobiological point of view, our results indicatedthat 3d-crt produces a lower ntcp for ipsilateral lung. in contrast, for tcpcalculations, there was a higher gain with imrt plans compared to 3d-crtplans.