Objective: To study the dosimetric effect on special reconstruction images obtained from an electrocardiograph-gated four-dimensional computed tomography (ECG 4D-CT) series and compare it with the accumulation dose assessment of ECG 4D-CT. Methods: Fifteen patients underwent ECG 4D-CT scans to obtain a 4D-CT series. The 20 phase images of 0-95% were reconstructed at intervals of 5% of the cardiac cycle by the 4D-CT series. The 4D-CT series was specially reconstructed, and the maximum intensity projection (MIP), minimum intensity projection (MinIP), average intensity projection (AIP), and sum intensity projection (SIP) were obtained. The left ventricular muscle (LV) and the anterior descending branch of the left coronary artery (LAD) were delineated on all series. The intensity-modulated radiation therapy (IMRT) plan for left breast cancer was designed on the basis of the 0% phase, and the accumulative dose (Dose-acc) of 20 phases was obtained by deformation registration. The dose-volume indexes of the LV and LAD were compared based on different CT series. Results: The dose-volume indices of V5, V30, V40, Dmax, and Dmean of the LV on MIP images were 3.8, 2.0, 0.9, 3.8, and 1.7%, respectively (relative to the Dose-acc). There was no significant difference in V5 or Dmax between the MIP and Dose-acc (P > 0.05). The change rates of Dmax on the MinIP, SIP, and AIP images were 2.5, 3.1, and 1.5%, respectively (relative to the Dose-acc) (P < 0.05). Conclusion: In the dose-volume evaluation of the LV, V30, V40, and Dmean obtained by MIP were essentially the same as those obtained by the Dose-acc and can be used instead of the 4D-CT series to evaluate dose-volume indexes.

中文翻译：

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研究4D-CT特殊重建图像对乳腺癌放射治疗中心脏结构剂量的影响。

目的：研究剂量对心电门控四维计算机断层扫描（ECG 4D-CT）系列获得的特殊重建图像的剂量效应，并将其与ECG 4D-CT的累积剂量评估进行比较。方法：15例患者接受了心电图4D-CT扫描以获得4D-CT系列。通过4D-CT系列，以心动周期的5％的间隔重建了0-95％的20个相位图像。专门重建了4D-CT系列，并获得了最大强度投影（MIP），最小强度投影（MinIP），平均强度投影（AIP）和总强度投影（SIP）。在所有系列中都描绘了左心室肌（LV）和左冠状动脉的前降支（LAD）。在0％相的基础上设计了左乳腺癌的调强放射治疗（IMRT）计划，并通过形变配准获得了20个相的累积剂量（Dose-acc）。根据不同的CT系列比较LV和LAD的剂量-体积指数。结果：在MIP图像上，LV的V5，V30，V40，Dmax和Dmean剂量剂量指数分别为3.8、2.0、0.9、3.8和1.7％（相对于Dose-acc）。MIP和Dose-acc之间的V5或Dmax没有显着差异（P> 0.05）。MinIP，SIP和AIP图像上Dmax的变化率分别为2.5％，3.1％和1.5％（相对于Dose-acc）（P <0.05）。结论：在LV，V30，V40，