Program Information
A Novel Study On a Fixed-Jaw Method IMRT Planning in Peripheral Lung Cancer Combined with Mediastinal Lymph Node Metastasis
H Wang1 , H Wang2*, (1) Shanghai Jiao Tong University Shanghai chest hospital, Shanghai, Shanghai, (2) Shanghai Jiao Tong University Shanghai chest hospital, Shanghai, Shanghai
Presentations
SU-I-GPD-T-313 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: In current planning system,jaw positions are automatically set to cover all target volumes by the planning system. Once lung tumors locates separately and radiation leakage and transmission increase total lung dose although blocked by MLC leaves,We evaluate the reduced lung dose derived from manually fixed jaw positions,and assess the correlation between the total lung dose volume reduction with the reduction of lung relative volume exposed by radiation leakage and transmission in fixed-jaw method
Methods: Twelve peripheral lung cancer combined with mediastinal lymph node metastasis patients treated with routine jaw auto-chosen plan were then re-planned with a fixed-jaw method.Paired t-tests were used to compare the following dosimetric parameters:2% and 98% PTV coverage dose;Conformality Index(CI); Homogeneity Index(HI); whole lung D2, V5, V10, V20, V30 and the mean dose; ipsilateral lung V5, V20 and the mean dose.Pearson rank tests were performed to determine the correlation of lung tissue dose volume reduction with the reduction of lung relative volume exposed by radiation leakage and transmission in the fixed-jaw plan
Results: 2 kinds of plans met clinical requirements;V5、V10、V20、V30 and mean dose for total lung were less than jaw auto-chosen plans(P＜0.002）,V5、V20 and mean dose for ipsilateral lung were also less than jaw auto-chosen plans(P＜0.017）. When using fixed-jaw method, the total lung dose volume reduction TLV5-△Vab (cc) and TLV10-△Vab(cc) value have moderate positive correlation with the reduction of LRVRLT: Σ△Si3/2(R=0.582,P=0.047;R=0.791,P=0.002); 2 values have higher positive correlation with the weighted reduction of LRVRLT:ΣMUi*△Si3/2(R=0.711,P=0.010;R=0.839,P=0.001).
Conclusion: Fixed-jaw plan is superior to jaw auto-chosen plan in reducing lung dose especially for peripheral lung cancer combined with mediastinal lymph node metastasis,and it could be applied in IMRT planning
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