Study on the position accuracy and repeatability of the whole upper limb fixed by negative pressure vacuum bag in IMRT after breast-conserving surgery for breast cancer
Objective To investigate the values of the position accuracy and repeatability of the whole upper limb fixed by negative pressure vacuum bag in intensity modulated radiotherapy(IMRT)after breast-conserving surgery.Methods A total of 34 patients with breast cancer treated with radiotherapy after breast-conserving surgery from October 2020 to May 2022 were randomly divided into experimental group and control group.The whole upper limb was fixed with the vacuum bags of 80 cm×120 cm in experimental group.The part upper limb was fixed with the vacuum bags of 70 cm×100 cm in control group,and the hands crossed in front of the forehead.Before and after treatment,the inter-fraction and intra-fraction setup errors(ΔP1 and ΔP2)in the left and right(X),head and feet(Y),ventral and dorsal(Z)three-dimensional directions were obtained.Three-dimensional directions external ranges from the clinical target volume(CTV)to the planning target volume(PTV)were calculated by the ΔP1.The body surface lines shifts of the three-dimensional directions before and after treatment(ΔP3)were calculated.The paired sample t-tests were performed for the same dirction set-up errors of ΔP1,ΔP2 and ΔP3 in the experimental and control group,respectively.The Pearson correlation analysis was performed for the ΔP1 and ΔP3 of the same dirction errors.Results There were no significance differences in the three-dimensional directions of ΔP1 between experimental group and control group(P>0.05).The PTV expansion values in the X,Y,and Z directions of the experimental and control groups were 4.97 mm,6.31 mm,5.38 mm,and 8.24 mm,9.96 mm,7.52 mm,respectively,with statistically significant differences(P=0.02).The ΔP2 of Z direction in the experimental and control groups was(0.29±1.02)mm and(-0.09±1.49)mm,respectively,and the ΔP3 values were(-0.63±0.95)mm and(-1.05±1.35)mm,respectively,with statistically significant differences between the two groups(P<0.05).There was an correlation between ΔP1 and ΔP3 in the Z direction of experimental and control groups(r=0.450,P<0.05;r=0.630,P<0.05).Conclusion The total upper limb fixed by vacuum bag can improve the position accuracy and repeatability in the whole breast IMRT after breast-conserving surgery for breast cancer,which might have certain clinical reference and promotion value.
Breast cancerIntensity modulated radiotherapy(IMRT)Vacuum bagBody position fixedSet-up er-rors
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