孔径形状控制器优化算法在立体定向放射治疗中的应用OACSTPCD

Objective:To evaluate the application of algo-rithm using aperture shape controller(ASC)in stereotactic body radiation therapy(SBRT)for brain metastasis,lung cancer and liver cancer.Methods:A retrospective analysis was performed for the radiotherapy plans for 20 brain metastasis patients,lung cancer patients and liver cancer patients,re-spectively.The planning system was Eclipse 15.6,and the prescription dose was 50 Gy/10 F,40 Gy/5 F and 40 Gy/5 F.Volumetric modulated arc therapy(VMAT)plan was designed in three ASC parameters,including very low(VMATVL)group,moderate(VMATM)group and very high(VMATVH)group.Target D90,D2,conformance index,gradient index and dosimetric parameters of organs at risk,monitor unit(MU)and modulation complexity score(MCS)were analyzed and compared among the three groups.One-way analysis of variance(one-way ANOVA)was used for comparison among groups.Results:There were no significant differences among three groups in dosimetry parameters for target(P＞0.05).In the brain metastasis plan,the V5 of brain tissue in the VMATVL group was better than in the VMATVH group,γ passing rate in the VMATVH group was higher than those in VMATVL and VMATM groups,the differences were statistically significant(P＜0.05).In the lung cancer plan,the results of D1000cc and D1500cc to lung in the VMATM group were better than those in the VMATVH group;MCS in the VMATVH group was higher than those in VMATVL and VMATM groups;γ passing rate in the VMATVH group was higher than that in the VMATVL group;MU in the VMATVL group was higher than those in VMATM and VMATVH groups,the differences were statistically significant(P＜0.05).In the liver cancer plan,the Dmax of esophagus in the VMATVL group was better than that in the VMATM group;the MCS in the VMATVH group was higher than those in VMATVL and VMATM groups(P＜0.05);the y passing rate in the VMATVH group was higher than that in the VMATM group(P＜0.05);the MU in the VMATVL group was higher than that in VMATVH group,the difference was statistically significant(P＜0.05).Conclusion:According to different clinical needs,such as prioritizing the protection of organs at risk,the rec-ommended ASC setting for SBRT for small volume brain metastasis,lung cancer and liver cancer is very low.If delivery effi-ciency and γ passing rate are prioritized,the ASC setting is recommended to be very high for SBRT for small volume brain metastasis,lung cancer and liver cancer.