A Dosimetric Comparison of Radiotherapy Techniques in the Treatment of Carcinoma of Breast

Abstract

Objectives of present study are a) to compare the planning and delivery aspects of five different techniques, planned by a) forward, inverse planning and electronic tissue compensation methods; and b) to evaluate and verify the accuracy of the planning system using phantom to estimate the skin dose for target and contraletral breast from five techniques. In-vivo skin dosimetry is planned with TL detectors. Five different radiotherapy techniques for treatment of carcinoma breast were studied using archived computed tomography (CT) scans of 25 breast conserving surgery patients (leftsided whole breast), planned for 50 Gy in 25 fractions. Linear accelerator (Clinac 2300 CD) photon beams were used and thermoluminescent detectors (TLD) [LiF:Mg, Ti] estimated dose on humanoid phantom. Dose coverage (95%) (to PTV) and hot spot (105%) covering volumes did not show differences (p > 0.05) in all 5 plans; Electronic compensator plans are better than others. IP-IMRT plan showed the worst Homogeneity Index (HI) (p , contra-lateral breast (CB) and heart OARs (V20 ipsi.lung, CB, V30 Heart,) are the least with IP-IMRT. IP-IMRT and E-COMP plans resulted in significantly lower mean dose to the superficial skin (Dmean, V40skin, 45skin, 50skin) (p the least doses to the skin of PTV and contra-lateral breast and less hot spots; E-COMP showed better homogeneity, fewer MUs, and the least dose in non-target zones.