Ramar Natarajan, Meher Samir Ranjan
Philips Health Systems, Philips India Limited, Bengaluru, Karnataka; Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
J Cancer Res Ther. 2023 Apr-Jun;19(3):688-696. doi: 10.4103/jcrt.jcrt_530_21.
We propose a novel metric called ψ - score to rank the Intensity Modulated Proton Therapy (IMPT) beams in the order of their optimality and robustness. The beams ranked based on this metric were accordingly chosen for IMPT optimization. The objective of this work is to study the effectiveness of the proposed method in various clinical cases.
We have used Pinnacle TPS (Philips Medical System V 16.2) for performing the optimization. To validate our approach, we have applied it in four clinical cases: Lung, Pancreas, Prostate+Node and Prostate. Basically, for all clinical cases, four set of plans were created using Multi field optimization (MFO) and Robust Optimization (RO) with same clinical objectives, namely (1) Conventional angle plan without Robust Optimization (CA Plan), (2) Suitable angle Plan without Robust Optimization (SA Plan), (3) Conventional angle plan with Robust Optimization (CA-RO Plan), (4) Suitable angle Plan with Robust Optimization (SA-RO Plan). Initial plan was generated with 20 equiangular beams starting from the gantry angle of 0°. In the corresponding SA Plan and SA-RO Plan, the beam angles were obtained using the guidance provided by ψ - score.
All CA plans were compared against the SA plans in terms of Dose distribution, Dose volume histogram (DVH) and percentage of dose difference. The results obtained from the clinical cases indicate that the plan quality is considerably improved without significantly compromising the robustness when the beam angles are optimized using the proposed method. It takes approximately 10-15 min to find the suitable beam angles without Robust Optimization (RO), while it takes approximately 20-30 min to find the suitable beam angles with RO. However, the inclusion of RO in BAO did not result in a change in the final beam angles for anatomies other than lung.
The results obtained in different anatomic sites demonstrate the usefulness of our approach in improving the plan quality by determining optimal beam angles in IMPT.
我们提出一种名为ψ评分的新指标，用于按强度调制质子治疗（IMPT）束的最优性和稳健性顺序对其进行排序。基于该指标排序的束相应地被选用于IMPT优化。这项工作的目的是研究该方法在各种临床病例中的有效性。
我们使用Pinnacle治疗计划系统（飞利浦医疗系统V 16.2）进行优化。为验证我们的方法，我们将其应用于四个临床病例：肺癌、胰腺癌、前列腺癌+淋巴结转移和前列腺癌。基本上，对于所有临床病例，使用多野优化（MFO）和稳健优化（RO）创建了四组计划，具有相同的临床目标，即（1）无稳健优化的传统角度计划（CA计划），（2）无稳健优化的合适角度计划（SA计划），（3）有稳健优化的传统角度计划（CA-RO计划），（4）有稳健优化的合适角度计划（SA-RO计划）。初始计划从机架角度0°开始，用20个等角束生成。在相应的SA计划和SA-RO计划中，束角度根据ψ评分提供的指导获得。
所有CA计划在剂量分布、剂量体积直方图（DVH）和剂量差异百分比方面与SA计划进行了比较。临床病例获得的结果表明，当使用所提出的方法优化束角度时，计划质量在不显著损害稳健性的情况下有相当大的提高。在无稳健优化（RO）的情况下找到合适的束角度大约需要10 - 15分钟，而在有RO的情况下找到合适的束角度大约需要20 - 30分钟。然而，除了肺部之外，在束角度优化（BAO）中纳入RO并没有导致其他解剖部位最终束角度的改变。
在不同解剖部位获得的结果证明了我们的方法在IMPT中通过确定最优束角度来提高计划质量的有用性。
