Feasibility Study of Beam Angle Optimization Based on Scripts in Automated-planning for Liver Cancer / 中国医疗器械杂志

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.

Quantitative comparison of volumetric-modulated arc therapy plans for liver cancer using flattening filter-free and flattening filter modes based on plan quality metric ( PQM) / 中华放射医学与防护杂志

Objective To quantitatively assess the plan quality of conventional fractionated volumetric modulated arc therapy ( VMAT ) plans for liver cancer treatments using flattening filter-free (FFF) and flattening filter (FF) modes based on plan quality metric (PQM). Methods A total of ten patients with liver tumor were selected. The patients were planned in FF and FFF mode of 6 MV X-ray respectively. The dose distribution of the planning target volume ( PTV) and the organ at risk ( OAR) were evaluated, and the monitor units ( MUs) and the beam on time ( BoT) were compared. According to the clinical requirements, a PQM with 16 submetrics was defined to evaluate the plan quality of the two modes. Results The maximal dose of FFF plan was less than that of FF plan (t =3.828, P <0.05). The normalized volume of 5 Gy ( V5 ) and mean dose ( Dmean ) of the normal liver of FFF plan were lower than those of the FF plan (t=2.716, 3.007, P<0.05). The average MU of FFF plan [(574 ± 130) MU] was higher than that of FF plan [(518 ± 81) MU](t= -2. 782,P<0. 05), while the average BoT of FFF plan [(108 ±36)s] was significantly lower than that of FF plan [(160 ±29) s](t=6.767,P<0.05). The score of FFF plan was higher than that of FF plan (t= -2.746, P<0.05). Conclusions FFF mode can better protect the OAR at low dose levels. The MU of FFF mode plan were higher, but the beam on time was significantly lower than FF mode plan. With reference to the PQM evaluation criteria, the overall plan quality of the FFF mode was slightly higher.