Gaur Garima, Dangwal Vinod Kumar, Banipal Raja Paramjeet Singh, Singh Ranjit, Kaur Gurpreet, Grover Romikant, Sachdeva Sheetal, Kang Manraj Singh, Singh Simrandeep, Garg Pardeep, Singh Baltej
Department of Radiation Oncology, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab, India.
Department of Radiation Oncology, Government Medical College, Patiala, Punjab, India.
J Med Phys. 2023 Apr-Jun;48(2):136-145. doi: 10.4103/jmp.jmp_28_23. Epub 2023 Jun 29.
The aim of the current study was to compare three different dose-calculating algorithms, i.e., superposition (SP), fast SP (FSP), and convolution (CV), for breast cancer patients treated with intensity-modulated radiotherapy (IMRT) and field-in-Field forward plan IMRT (FiF-FP-IMRT).
The current retrospective study involved 100 postmastectomy breast cancer patients who were given radiotherapy using IMRT and FiF-FP-IMRT planning techniques. All the initially SP-calculated plans were recalculated with the same monitor units for FSP and CV algorithm without change in any of the other planning parameters. The isodose distribution and various plan evaluating parameters, for example, conformity index (CI), homogeneity index, and uniformity index target volume and normal structure doses were compared and analyzed for all the different algorithm calculated plans.
In the IMRT plans, all the target and normal structure dose-volume parameters showed a significant difference between all the three different algorithms with < 0.05. In the FiF-FP-IMRT plans, CV algorithm showed a significant difference in most of the target and normal structure dose-volume parameters. Among quality indexes, only CI showed a significant difference between all the algorithms in both the planning techniques. R showed a significant difference with the CV algorithm in both the planning techniques.
The change in the dose calculation algorithm resulted in dosimetric changes which must be evaluated by the medical physicists and oncologists while evaluating treatment plans. In the current study with breast patients, the results obtained for target and normal structure doses using the CV algorithm are overestimated as compared to SP and FSP algorithms, producing variable results in air and bony normal structures. However, the ipsilateral lung V parameter and the ipsilateral humeral head mean dose were found to be underestimated by the CV algorithm as compared to the SP and FSP algorithm in both the planning techniques.
本研究的目的是比较三种不同的剂量计算算法，即叠加法（SP）、快速叠加法（FSP）和卷积法（CV），用于接受调强放疗（IMRT）和野中野正向计划IMRT（FiF-FP-IMRT）治疗的乳腺癌患者。
本回顾性研究纳入了100例接受乳房切除术后放疗的乳腺癌患者，采用IMRT和FiF-FP-IMRT计划技术。所有最初用SP算法计算的计划，在不改变任何其他计划参数的情况下，使用相同的监测单位，用FSP和CV算法重新计算。比较并分析了所有不同算法计算计划的等剂量分布和各种计划评估参数，如适形指数（CI）、均匀性指数、均匀度指数、靶区体积和正常结构剂量。
在IMRT计划中，所有三种不同算法之间的所有靶区和正常结构剂量体积参数均显示出显著差异，P<0.05。在FiF-FP-IMRT计划中，CV算法在大多数靶区和正常结构剂量体积参数上显示出显著差异。在质量指标中，只有CI在两种计划技术的所有算法之间显示出显著差异。在两种计划技术中，R与CV算法均显示出显著差异。
剂量计算算法的改变导致了剂量学变化，在评估治疗计划时，医学物理师和肿瘤学家必须对其进行评估。在本乳腺癌患者研究中，与SP和FSP算法相比，使用CV算法获得的靶区和正常结构剂量结果被高估，在空气和骨性正常结构中产生了可变结果。然而，在两种计划技术中，与SP和FSP算法相比，CV算法均低估了同侧肺V参数和同侧肱骨头平均剂量。
