Mishra Vishwadeep, Chaudhary Shwetima, Singh Prarabdh, Pandey Laxman, Pandey Archana, Chatterjee Rachita
Radiation Oncology, All India Institute of Medical Sciences, Gorakhpur, Gorakhpur, IND.
Radiation Oncology, T.S Misra Medical College and Hospital, Lucknow, IND.
Cureus. 2024 Aug 30;16(8):e68182. doi: 10.7759/cureus.68182. eCollection 2024 Aug.
Introduction Esophageal cancer remains a leading cause of cancer-related mortality worldwide, with chemoradiotherapy being a cornerstone of its treatment. Ensuring precise radiation delivery is critical, as it minimizes exposure to surrounding healthy tissues, particularly vital structures like the heart and the left anterior descending artery (LAD). Volumetric arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) are two advanced radiotherapy techniques that offer enhanced dose conformity and reduced toxicity. This study conducts a retrospective dosimetric analysis to compare the effectiveness of VMAT and IMRT in sparing cardiac substructures and the LAD in patients with carcinoma of the esophagus. Methods Ten patients with middle-third esophageal cancer were treated using the VMAT technique with two coplanar arcs. These patients were retrospectively re-planned with IMRT using 7-9 fields on the Varian TrueBeam linear accelerator between June 2023 and December 2023. VMAT planning involved a two-phase approach: 45 Gy in 25 fractions followed by a boost of 5.4 Gy in three fractions. Dose-volume histograms were analyzed and compared for the planning target volume (PTV), heart and its substructures (including the right atrium, right ventricle, left atrium, and left ventricle), and the LAD. Statistical significance was determined using paired t-tests with a significance level set at P < 0.05. Results PTV coverage was comparable between VMAT and IMRT. VMAT resulted in higher low-dose exposure (V5 and V10) but offered better sparing at moderate doses (V20 and V40) for the heart. The LAD benefited from reduced high-dose exposure with VMAT. For other cardiac substructures, VMAT generally showed higher low-dose exposure but provided superior sparing at moderate doses compared to IMRT. Conclusions VMAT offers notable dosimetric advantages in sparing critical cardiac structures compared to IMRT for treating patients with middle third esophageal cancer. Long-term follow-up studies are needed to assess how these dosimetric benefits influence coronary artery disease and other cardiac complications.
引言 食管癌仍然是全球癌症相关死亡的主要原因，放化疗是其治疗的基石。确保精确的放疗至关重要，因为这可将周围健康组织，尤其是心脏和左前降支动脉（LAD）等重要结构的暴露降至最低。容积弧形调强放疗（VMAT）和调强放疗（IMRT）是两种先进的放疗技术，可提供更高的剂量适形性并降低毒性。本研究进行了一项回顾性剂量分析，以比较VMAT和IMRT在食管癌患者中保护心脏亚结构和LAD的有效性。方法 10例中段食管癌患者采用VMAT技术和两个共面弧形进行治疗。2023年6月至2023年12月期间，在瓦里安TrueBeam直线加速器上对这些患者进行回顾性IMRT重新计划，使用7-9个野。VMAT计划采用两阶段方法：25次分割给予45 Gy，随后3次分割给予5.4 Gy的推量。分析并比较了计划靶区（PTV）、心脏及其亚结构（包括右心房、右心室、左心房和左心室）以及LAD的剂量体积直方图。使用配对t检验确定统计学意义，显著性水平设定为P < 0.05。结果 VMAT和IMRT之间的PTV覆盖相当。VMAT导致更高的低剂量暴露（V5和V10），但在中等剂量（V20和V40）时对心脏的保护更好。LAD受益于VMAT降低的高剂量暴露。对于其他心脏亚结构，VMAT通常显示出更高的低剂量暴露，但与IMRT相比，在中等剂量时提供了更好的保护。结论 与IMRT相比，VMAT在治疗中段食管癌患者时，在保护关键心脏结构方面具有显著的剂量学优势。需要进行长期随访研究，以评估这些剂量学益处如何影响冠状动脉疾病和其他心脏并发症。
