Effect of Set-up Error on Cardiac Dose in Postoperative Radiotherapy Patients with Breast Cancer
Objective To investigate the effect of simulated set-up error on cardiac irradiation dose of left breast cancer patients after postoperative radiotherapy.Methods A total of 17 left breast cancer patients undergone modified radical mastectomy were enrolled as research object.In the planning system,the deviation of the center of the target volume relative to the center of the planned field was simulated,including moving 5 mm each towards the superior(S),inferior(I),left(L),right(R),anterior(A),and posterior(P).The cardiac irradiation dose was then assessed,with an analysis focusing on the influence of these set-up errors on cardiac dose.Results The mean cardiac irradiation dose(Dmean)of the original plan was 5.72 Gy.After the isocenter of irradiation beam were moved with 5 mm in six different directions,the cardiac irradiation dose decreased at the L,A,and S directions,while the cardiac irradiation dose increased at the R,P,and I directions.The cardiac irradiation dose Dmean increased by(1.46±0.24)Gy at the P direction,(1.14±0.17)Gy at the R direction,and(0.43±0.25)Gy at the I direction.Conclusion Set-up errors in the R,P,I directions during radiotherapy after modified radical mastectomy for left breast cancer can result in an elevated dose of cardiac irradiation.Set-up errors in the L,A,S directions can decrease the cardiac irradiation dose.
breast cancermodified radical mastectomyradiation therapyset-up errorcardiac dose
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