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OBJECTIVE@#To study the feasibility and potential benefits of beam angle optimization (BAO) to automated planning in liver cancer.@*METHODS@#An approach of beam angle sampling is proposed to implement BAO along with the module Auto-planning in treatment planning system (TPS) Pinnacle. An in-house developed plan quality metric (PQM) is taken as the preferred evaluating method during the sampling. The process is driven automatically by in-house made Pinnacle scripts both in sampling and scoring. In addition, dosimetry analysis and physician's opinion are also performed as the supplementary and compared with the result of PQM.@*RESULTS@#It is revealed by the numerical analysis of PQM scores that only 15% patients whose superior trials evaluated by PQM are also the initial trials. Gantry optimization can bring benefit to plan quality along with auto-planning in liver cancer. Similar results are provided by both dose comparison and physician's opinion.@*CONCLUSIONS@#It is possible to introduce a full automated approach of beam angle optimization to automated planning process. The advantages of this procedure can be observed both in numerical analysis and physician's opinion.
Subject(s)
Humans , Radiotherapy Planning, Computer-Assisted/methods , Feasibility Studies , Radiometry/methods , Liver Neoplasms/radiotherapy , Radiotherapy, Intensity-Modulated/methods , Radiotherapy DosageABSTRACT
Objective:To propose an automatic planning method of intensity-modulated radiotherapy (IMRT) for esophageal cancer based on dose volume histogram prediction and beam angle optimization in Raystation treatment planning system.Methods:50 IMRT plans of esophageal cancer were selected as the training set to establish a dose prediction model for organs at risk. Another 20 testing plans were optimized in Raystation using RuiPlan and manual method, and the beam angle optimization and dose volume histogram prediction functions of RuiPlan were used for automatic planning. Dosimetric differences and planning efficiency between two methods were statistically compared with paired t-test. Results:There were no significant dosimetric differences in the conformity index (CI), homogeneity index (HI) of PTV, V 5Gy of both lungs and D max of the spinal cord between automatic and manual plans (all P>0.05). Compared with those in the manual plans, the V 20Gy and D mean of the left and right lungs generated from automatic plans were reduced by 1.1%, 0.37 Gy and 1.2%, 0.38 Gy (all P<0.05), and the V 30Gy, V 40Gy and D mean of the heart in automatic plans were significantly decreased by 5.1%, 3.0% and 1.41 Gy, respectively (all P<0.05). The labor time, computer working time, and monitor unit (MU) number of automatic plans were significantly decreased by 65.8%, 14.1%, and 17.2%, respectively (all P<0.05). Conclusion:RuiPlan automatic planning scripts can improve the efficiency of esophageal cancer planning by dose prediction and beam angle optimization, providing an alternative for esophageal cancer radiotherapy planning.
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Objective To study the dosimetric impact of different angle fields in intensitymodulated radiotherapy (IMRT) and the feasibility of beam angle optimization (BAO) for multiple intracranial metastases.Methods In total,11 patients with multiple intracranial metastases were included in these analyses.Two treatment techniques were designed for each patient:the 7 equal spaced fields (BAF group) IMRT,and 7 fields by beam angle optimization (BAO group) IMRT.The dose distribution in the target,the dose to the organs at risk and normal brain tissues,and total MU in two groups were compared to explore the dosimetric differences.Results In comparison to the BAF group,the BAO group reduced the maximum dose to left and right lenses by an average of 45％,37％ (t =-5.707,-4.438,P ＜ 0.05);the mean dose to the left and right eyes were reduced by an average of 42.6％,44.5％ (t =-4.380,-5.638,P ＜0.05);the maximum dose to the right eyes were reduced by an average of 32.5％ (t =-2.518,P ＜ 0.05).The maximum dose of the right optic nerve and the mean dose of normal brain tissue were reduced by an average of 23％ and 3％ (t =-3.105,-3.437,P ＜0.05),respectively.For the target dose,conformity and homogeneity in PTV,no statistical differences were observed between the two groups (P ＞ 0.05).The BAO group reduced the maximum dose of the brainstem and the optic chiasm,as well as the number of MU,however,the differences were not statistically significant (P ＞ 0.05).Conclusions In comparison to the BAF group,the BAO group shows a similar target dose and reduces the dose for the organs at risk.For multiple intracranial metastases,IMRT protocols with BAO are feasible and beneficial.
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Objective To study the dosimetry characteristics of 9 equal spaced fields and 9 fields with beam angle optimization (BAO) process for cervix uteri.Methods 12 cervix uteri cancer patients CT Images were transferred into Eclipse planning system.Each patient,the 9 equal spaced fields and 9 fields by BAO process were IMRT plan designed with the same CT image.Make a evaluation of dose distribution for target volume and OARs,and paired t test for them.Results Comparing to 9 equal spaced fields IMRT plan,the quality of 9 fields IMRT plan with BAO process the the PTV V95％ was 99.31％ vs 99.42％,P =0.020,at the same time V105％,V110％,Dmax,D got 60.54％ vs 47.92％,P =0.013;7.14％ vs 0.37％,P =0.000;56.62 Gy vs 55.47 Gy,P =0.000;53.29 Gy vs 52.72 Gy,P =0.000,the CI and HI was 0.85 vs 0.89,P =0.000 ;0.10 vs 0.13,P =0.000.For organs at risk,bladder V40 was increased by 4.7 ％ (P =0.013) ;the D40 of rectum was 0.5 Gy higher (P =0.004) ; the small bowel's DVH showed that V40 and Dmax increased by 0.6％ (P =0.015) and 1.4 Gy (P =0.000),D of bone marrow were raised separately by 1.3 Gy (P =0.000),the spinal cord's dose D0.1 cm3 was also increased by 2.0 Gy (P =0.000).Conclusion The quality of 9 equal spaced fields IMRT plan will be better than those achieved by BAO process optimized plans.