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Objective To study the left breast cancer postoperative radiotherapy dosimetry difference of three type different radiotherapy plans.Methods 15 cases of postoperative patients with left breast cancer respectively,design 3 d-CRT,dIMRT and RapidArc planning,prescription doses of 5000 cgy.Dose volume histogram analysis clinical target CTV,endanger organ OARs of each evaluation index.Results 3 d-CRT plan except the HI,D2%in each evaluation index,are inferior to dIMRT and RapidArc plans(P < 0.05).dIMRT compared with RapidArc plan,only in Dmean,V95%difference was statistically significant(P < 0.05),and in RapidArc plan Dmean closer to the prescription dose,V95%coverage rate is as high as 97.44%.Three plans for ipsilateral lung,in 3 d-CRT V5,V10 lowest(P < 0.05),while V20,V30 was the highest(P < 0.05).RapidArc and dIMRT ipsilateral lung V5,V10 slightly higher(P < 0.05).The contralateral lung and heart-3 d CRT minimum each index(P < 0.05).The contralateral breast D1%criterion with low dIMRT and RapidArc plans,were 1770.89+/-121.16 cGy,1839.92+/-92.77 cGy.And D1%of spinal cord for dIMRT and RapidArc plans are higher,respectively was 1990.12+/-61.52 cGy,1927.38+/-43.67 cGy.Normal tissue to accept dose for 5 to 15 Gy for 3 d-CRT program significantly lowest volume,the RapidArc plans are relatively high.RapidArc plan MU and treatment time,at least only for dIMRT plan of 49.33%and 55.86%.Conclusions Three types of plans are able to satisfy the requirement of the left breast cancer postoperative radiotherapy clinical dosimetry.dIMRT and RapidArc plan better suited to target,and RapidArc plan has the advantages of less total MU,total treatment time.