Hodgkin lymphomas are radiosensitive and curable tumors that often involve the mediastinum. However, the application of radiation therapy to the mediastinum is associated with late effects including cardiac and pulmonary toxicities and secondary cancers. The adoption of conformal IMRT and deep inspiration breath- hold (DIBH) can reduce the dose to healthy normal tissues (lungs, heart and breast). We compared the dosimetry of organs at risk (OARs) using different IMRT techniques for two breathing conditions, i.e., deep inspiration breath hold (DIBH) and free breathing. Twenty-three patients with early-stage mediastinal Hodgkin lymphomas were accrued in the prospective study. The patients were given treatment plans which utilized full arc volumetric modulated arc therapy (F-VMAT), Butterfly VMAT (B-VMAT), and fixed field IMRT (FF-IMRT) techniques for both DIBH and free breathing methods, respectively. All the plans were optimized to deliver 95% of the prescription dose which was 25.2 Gy to 95% of the PTV volume. The mean dose and standard error of the mean for each OAR, conformity index (CI), and homogeneity index (HI) for the target using the three planning techniques were calculated and compared using Student’st-test for parametric data and Wilcoxon signed-rank test for non-parametric data. The HI and CI of the target was not compromised using the DIBH technique for mediastinal lymphomas. The mean values of CI and HI for both DIBH and FB were comparable. The mean heart doses were reduced by 2.1 Gy, 2.54 Gy, and 2.38 Gy in DIBH compared to FB for the F-VMAT, B-VMAT, and IMRT techniques, respectively. There was a significant reduction in V5Gy, V10Gy, and V15Gy to the heart (p< 0.005) with DIBH. DIBH reduced the mean dose to the total lung by 1.19 Gy, 1.47 Gy, and 1.3 Gy, respectively. Among the 14 female patients, there was a reduction in the mean right breast dose with DIBH compared to FB (4.47 Gy vs. 3.63 Gy,p= 0.004). DIBH results in lower heart, lung, and breast doses than free breathing in mediastinal Hodgkin Lymphoma. Among the different IMRT techniques, FF-IMRT, B-VMAT, and F-VMAT showed similar PTV coverage, with similar conformity and homogeneity indices. However, the time taken for FF-IMRT was much longer than for the F-VMAT and B-VMAT techniques for both breathing methods. B-VMAT and F-VMAT emerged as the optimal planning techniques able to achieve the best target coverage and lower doses to the OARs, with less time required to deliver the prescribed dose.
霍奇金淋巴瘤是对放射治疗敏感且可治愈的肿瘤，常累及纵隔。然而，纵隔放射治疗的应用与远期效应相关，包括心脏和肺毒性以及继发性癌症。采用适形调强放射治疗（IMRT）和深吸气屏气（DIBH）技术可降低健康正常组织（肺、心脏和乳腺）的照射剂量。本研究比较了在两种呼吸条件下（即深吸气屏气与自由呼吸）使用不同IMRT技术对危及器官（OARs）的剂量学影响。这项前瞻性研究纳入了23例早期纵隔霍奇金淋巴瘤患者。分别为每例患者制定了采用全弧容积旋转调强放疗（F-VMAT）、蝶形VMAT（B-VMAT）和固定野IMRT（FF-IMRT）技术的治疗计划，并分别适配DIBH和自由呼吸模式。所有计划均经过优化，使95%的计划靶区体积接受95%的处方剂量（25.2 Gy）。计算并比较了三种计划技术下各危及器官的平均剂量及标准误、靶区的适形指数（CI）和均匀性指数（HI），参数数据采用Student's t检验，非参数数据采用Wilcoxon符号秩检验。对于纵隔淋巴瘤，DIBH技术并未影响靶区的HI和CI，DIBH与自由呼吸的CI和HI平均值具有可比性。在F-VMAT、B-VMAT和IMRT技术中，DIBH较自由呼吸分别使心脏平均剂量降低2.1 Gy、2.54 Gy和2.38 Gy。DIBH显著降低了心脏的V5Gy、V10Gy和V15Gy（p<0.005）。DIBH使全肺平均剂量分别降低1.19 Gy、1.47 Gy和1.3 Gy。在14例女性患者中，DIBH较自由呼吸降低了右乳腺平均剂量（4.47 Gy对比3.63 Gy，p=0.004）。对于纵隔霍奇金淋巴瘤，DIBH能降低心脏、肺和乳腺的照射剂量。在不同IMRT技术中，FF-IMRT、B-VMAT和F-VMAT显示出相似的靶区覆盖度，以及相近的适形指数和均匀性指数。然而，在两种呼吸模式下，FF-IMRT所需时间均远长于F-VMAT和B-VMAT技术。B-VMAT和F-VMAT成为最优计划技术，能够在更短的时间内实现最佳靶区覆盖和更低的危及器官剂量。
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