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Objective To investigate the difference of styrofoam and breast carrier in postposition fixation of intensity-modulated radiotherapy after breast conservative surgery for breast cancer patients.Methods From February 2018 to August 2018,tweenty-four patients with breast cancer in Sun Yet-Sen Memorial Hospital of Sun Yet-sen University were selected for this study,who underwent hypofactionationed radiotherapy after breast conservative surgery with total dose 42.56 Gy/16Fractions.They were randomized into styrofoam test group and breastcarrier control group.Cone beam CT as used to record the positioning error under the directions of left and right (x),head and foot (y),abdomen and back (y) within two groups at the first,third,fifth,seventh,eleventh time before irradiation.Furthermore,the PTV extension margin was calculated and the positioning time of two groups was recorded.Two sets of pendulum errors were analyzed by independent sample T-test,and the outspread value of inter-fractional set up error of the PTV was calculated.Results The errors of the test group and the control group in the direction of x,y,z were as follows:(2.36±1.89) and (2.56±2.05) mm (P=0.49),(1.76± 1.78) and (3.28±2.79) mm (P＜0.05),(1.47± 1.49) and (1.73± 1.81) mm (P=0.28).The extension values of inter-fractional set up error of CTV to PTV were 2.97,2.92,2.21 mm and 3.41,4.09,2.59 mm respectively.The time of single positioning was (3.4± 1.1) and (5.5 ± 3.1) min respectively (P=0.01).Conclusion Styrofoam has better positioning accuracy and efficiency compared with breast carrier.
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Objective@#To compare the dosimetric parameters of target volumes and organs at risk between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for left sided breast cancer after breast-conserving surgery by a meta-analysis.@*Methods@#Literature search was performed to include related studies to analyze the dosimetric parameters of target volumes and organs at risk.@*Results@#A total of 11 studies involving 154 patients were included in meta-analysis. There were no significant differences in Dmean, HI of PTV-Whole breast and PTV-Boost. Comparing to IMRT, VMAT increased the conformity index (CI) of PTV-Whole breast (P=0.000) and PTV-Boost (P=0.002). When the mean volume of target volumes was≤634 cm3, there were no significant differences in Dmean, V5, V20 of the heart and left sided lung, V30 of the heart, Dmean of the right sided lung and breast between VMAT and IMRT.When the mean volume of target volumes was>634 cm3, the Dmean(P=0.037), V5(P=0.005) and V20(P=0.030) of the heart in IMRT was lower than VMAT, but the V30(P=0.001) of heart in VMAT was lower than IMRT.IMRT showed significantly lower Dmean(P=0.013), V5(P=0.000), V20(P=0.000) of the left sided lung, and Dmean(P=0.001) of the right sided lung than VMAT.There were no significant differences in Dmean of the right sided breast.@*Conclusions@#There were no significant differences in dosimetric parameters of target volumes between VMAT and IMRT.When the mean volume of target volumes was≤634 cm3, there were no significant differences in dosimetric parameters of organs at risk. When the mean volume of target volumes was>634 cm3, IMRT has some advantages in protection of the heart and lung.
Résumé
Objective To investigate the impacts of planning target volume (VPTV),maximal heart distance (MHD),central lung distance (CLD),and cardiothoracic ratio (CTR) on intensity-modulated radiotherapy (IMRT) after breast-conserving surgery for breast cancer.Methods Forty-eight patients with breast cancer (31 with left-sided breast cancer and 17 with right-sided breast cancer) who received whole-breast IMRT after breast-conserving surgery in our hospital from 2016 to 2017 were enrolled as subjects.The prescribed radiation dose tor PTV was 50 Gy in 25 fractions.In IMRT planning for each patient,the objective function was optimized using physical parameters and the equivalent uniform dose.The relationship of influencing factors with dose-volume histogram,conformal index (CI),and homogeneity index (HI) for organ at risk was predicted using univariate and multivariate linear regression analyses.Results CTR and VPTV were independent influencing factors for CI in patients with left-sided breast cancer (R2=0.56,P=0.04;R2 =0.56,P=0.00).CLD was an independent influencing factor for HI in patients with left-sided breast cancer (R2=0.17,P=0.023).VPTV was an independent influencing factor for CI in patients with right-sided breast cancer (R2 =0.48,P=0.00).MHD and CTR were predictors for VHeart30 of the heart.MHD and CLD were predictors for DmaxHeart of the heart.The prediction formulae for left-sided breast cancer were CI=0.38+0.32CTR and HI=1.06+0.02CLD.CI was 0.48 at the right side.At the left side,Vlung20=12.68+3.18CLD,Vlung10=18.78+4.3CLD,Vlung5=26.2+5.2CLD,and Dmeanlung=686.7+210.ICLD.For the heart,VHeart30=-13.65+30.5CTR+1.9MHD and DmaxHeart =5 140.1 +248.9MHD-195.6CLD.There was no correlation of patient's heart volume with MHD,VHeart10,VHeart5,DmeanHeart,or DmaxHeart.There was no correlation of whole lung volume with CLD,Vlung20,Vlung10,Vlung5,or Dmeanlung.The mean values of CI and HI were 0.63± 0.06 (0.46-0.72) and 1.09± 0.02 (1.07-1.14-) in radiotherapy plans for left-sided breast cancer,and 0.65± 0.08 (0.4-8-0.76) and 1.09± 0.04 (1.03-1.18) in radiotherapy plans for right-sided breast cancer,respectively.Conclusions CTR,CLD,and MHD can predict the rationality of each parameter in IMRT planning for left-sided breast cancer rather than right-sided breast cancer.The obtained formulae can help physicians choose the optimal setting mode for radiation field and improve the quality of treatment plans.
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Objective To evaluate the dosimetric difference between fixed-field static intensity-modulated radiotherapy (IMRT), fixed-field dynamic multileaf collimator (DMLC), and volumetric modulated arc therapy (VMAT), all of which involve supraclavicular and infraclavicular regions, in breast cancer patients after breast-conserving surgery.Methods This study included 14 female patients with breast cancer who received radiotherapy after breast-conserving surgery in our hospital from October 2012 to April 2016.The radiation field included the chest wall and supraclavicular and infraclavicular regions.IMRT, DMLC, and VMAT plans were generated for each patient while using identical optimization conditions.The doses to planning target volume (PTV) and organs at risk (OARs) were compared based on dose-volume histogram (DVH);one-way analysis of variance or nonparametric Wilcoxon rank test was used for comparison.Results For the dose distribution of PTV, VMAT achieved the best V95, V98, CI, and HI (P<0.009).Concerning the doses to OARs, VMAT achieved the best V5, V20, and Dmean of the ipsilateral lung and the best V5 and Dmean of the contralateral lung (P<0.022).Dmean of the spinal cord was significantly lower in VMAT than in IMRT and DMLC (P=0.004).Conclusions VMAT is preferred for the patients with breast cancer to be treated with radiotherapy involving supraclavicular and infraclavicular regions after breast-conserving surgery.It can improve the dose distribution of target and reduce the doses to organs at risk and radiotherapy toxicities.