Medicalconsult SA, Campo Grande, n° 56 - 8° A, 1700-093 Lisboa, Portugal.
Escola Superior de Tecnologias da Saúde, Avenida Dom João II, 1900-096 Lisboa, Portugal.
Phys Med. 2014 Mar;30(2):160-70. doi: 10.1016/j.ejmp.2013.04.006. Epub 2013 Jun 2.
This work aims at investigating the impact of treating breast cancer using different radiation therapy (RT) techniques--forwardly-planned intensity-modulated, f-IMRT, inversely-planned IMRT and dynamic conformal arc (DCART) RT--and their effects on the whole-breast irradiation and in the undesirable irradiation of the surrounding healthy tissues. Two algorithms of iPlan BrainLAB treatment planning system were compared: Pencil Beam Convolution (PBC) and commercial Monte Carlo (iMC). Seven left-sided breast patients submitted to breast-conserving surgery were enrolled in the study. For each patient, four RT techniques--f-IMRT, IMRT using 2-fields and 5-fields (IMRT2 and IMRT5, respectively) and DCART - were applied. The dose distributions in the planned target volume (PTV) and the dose to the organs at risk (OAR) were compared analyzing dose-volume histograms; further statistical analysis was performed using IBM SPSS v20 software. For PBC, all techniques provided adequate coverage of the PTV. However, statistically significant dose differences were observed between the techniques, in the PTV, OAR and also in the pattern of dose distribution spreading into normal tissues. IMRT5 and DCART spread low doses into greater volumes of normal tissue, right breast, right lung and heart than tangential techniques. However, IMRT5 plans improved distributions for the PTV, exhibiting better conformity and homogeneity in target and reduced high dose percentages in ipsilateral OAR. DCART did not present advantages over any of the techniques investigated. Differences were also found comparing the calculation algorithms: PBC estimated higher doses for the PTV, ipsilateral lung and heart than the iMC algorithm predicted.
本研究旨在探讨采用不同放射治疗（RT）技术治疗乳腺癌的效果，包括正向计划调强放疗（f-IMRT）、逆向计划调强放疗（IMRT）和动态适形弧放疗（DCART），及其对全乳照射和周围健康组织的不良照射的影响。比较了 iPlan BrainLAB 治疗计划系统的两种算法：笔形束卷积（PBC）和商业蒙特卡罗（iMC）。纳入了 7 名接受保乳手术的左侧乳腺癌患者。对每位患者应用了 4 种 RT 技术：f-IMRT、双野和 5 野 IMRT（IMRT2 和 IMRT5）和 DCART。通过剂量体积直方图分析比较计划靶区（PTV）和危及器官（OAR）的剂量分布；进一步使用 IBM SPSS v20 软件进行统计分析。对于 PBC，所有技术均能充分覆盖 PTV。然而，在 PTV、OAR 以及剂量分布扩散到正常组织的模式方面，不同技术之间存在显著的剂量差异。与切线技术相比，IMRT5 和 DCART 使更多的正常组织、右侧乳腺、右侧肺和心脏受到低剂量照射。然而，与其他技术相比，IMRT5 计划改善了 PTV 的分布，在靶区具有更好的适形性和均匀性，并降低了同侧 OAR 的高剂量百分比。DCART 与所研究的技术相比没有优势。比较计算算法也发现了差异：与 iMC 算法相比，PBC 估计 PTV、同侧肺和心脏的剂量更高。
