Effect of limiting value of subfield number on dosimetry of intensity-modulated radiotherapeutic plan for left-breast radical mastectomy
Objective To investigate the effect of the limiting value of subfield number on the dosime-try of intensity-modulated radiotherapy (IMRT) plan for left-breast radical mastectomy in order to seek the optimal limiting value of subfield number.Methods The clinical data of 30 patients with left-breast radical mastectomy in this hospital from March 1,2022 to March 31,2023 were retrospectively analyzed.All patients used the Oncentra 4.3 planning system to design 5 kinds of IMRT plans,and the limiting values of subfield number were 15,25,35,45 and 55 respectively (all IMRT plans were named according to the subfield number limiting value,the other optimization parameters and objective function were the same),planning target vol-ume (PTV) dosimetric parameters,organ at risk (OAR) receiving dosage and monitor units were statistically analyzed and compared.Results The PTV D2％ (F=104.439,P<0.05),D98％ (F=20.748,P<0.05),Dmean (F=89.578,P<0.05),homogeneity index (HI,F=101.794,P<0.05) and conformity index (CI,F=26.453,P<0.05) among different subfields number limiting values of IMRT had statistical differences,the left side humeral head V50 (F=76.991,P<0.05) had significant difference and the other OAR had no signifi-cant difference (P>0.05).The PTV D2％,D98％,Dmean,CI and HI values of plan35 were significantly superior to those of plan15 and plan25,and the differences were statistically significant (P<0.05).Compared with plan35,there were no statistically significant difference in PTV D98％ and CI of plan45 and plan55 (P>0.05),while the PTV D2％,Dmean and HI were lower,and the difference was statistically significant (P<0.05).The V50 of left humeral head in plan15 and plan25 were too high to meet the clinical request.The plan35,plan45 and plan55 could protect the OAR well,moreover there were no significant difference in the receiving dosage of the OAR (P>0.05).The monitor units of plan35 was lower than that of plan45 and plan55,and the difference was statistically significant (P<0.05).Conclusion When the limiting value of subfield number is 35,the dose distribution of PTV and OAR receiving dosage meet the clinical dosimetric requirements,meanwhile the monitor units is lower,which can be used as a reference value for the IMPT plan design for left-breast cancer radical mastecto-my.
intensity-modulated radiation therapylimiting value of subfield numberbreast cancerdosimetry
万方数据
维普
