Effect of Positioning Error on Radiotherapy Planning Dose After Breast Conserving Surgery
Objective To analyze the effect of positioning error on radiotherapy planning dose after breast conserving surgery for breast cancer.Methods A total of 15 female patients with left and right breasts conserving surgery were selected as the study objects,respectively.By moving the treatment center of the treatment plan to simulate the positioning errors,the effect of different positioning errors on D95 of clinical target volume(CTV-D95),D95 of CTV-boost(CTV-boost-D95)was analyzed,as well as the effects on organs at risk(lung V5,lung V20,Dmean in the health-side breast,Dmean in the heart of left breast patients.Results When the set-up error was in the one direction within 0.5 cm,the CTV-D95 was close to the original plan,and the dose of organs at risk was significantly reduced in the direction of the treatment center bias to the affected side breast,head,and abdomen.The average of CTV-D95 was significantly reduced,and the dose of organs at risk was significantly increased in the treatment center bias to the healthy side breast,foot,back.Among them,the dose variation in the treatment center was the largest in the back direction,but all of them were in the clinically acceptable range.The planned dose effect was also acceptable when the treatment center was simultaneously bias to the affected side breast,head,and abdomen within 0.5 cm or simultaneously bias to the healthy side breast,foot,back within 0.3 cm.When the treatment center was simultaneously bias to the healthy side breast,foot,back reaches 0.5 cm,CTV-D95,CTV-boost-D95 were less than 95%of the prescription dose,and the average value of V20 in the lung had exceeded the dose limit,and the actual dose did not meet the clinical requirements.Conclusion When the average set-up error of this radiotherapy center is less than 0.3 cm in the direction of the X,Y,and Z,the dose effect caused by the set-up error is basically in the scope of clinical acceptance.It should be attracted great attention to the therapist when the treatment center is simultaneously bias to the healthy side breast,foot,back reaches 0.5 cm,and the number of CBCT can be appropriately increased.
breast cancerradiotherapy after breast conserving surgeryCBCTset-up errorsdose effect
国家科技期刊平台
NSTL
万方数据
维普
