The study investigated the dosimetric impact of an iterative metal artifact reduction (iMAR) tool on carbon ion therapy for pelvic cancer patients with hip prostheses. An anthropomorphic pelvic phantom with unilateral and bilateral hip prostheses was used to simulate pelvic cancer patients with metal implants. The raw data obtained from phantom CT scanning were reconstructed with a regular filtered back projection (FBP) algorithm and then corrected with iMAR. The phantom without hip prosthesis was also scanned and used as a reference ground truth (GT). The CT images of three prostate and four sarcoma patients with unilateral hip prosthesis were also reconstructed by FBP and iMAR algorithm and compared. iMAR algorithm reduced the metal artifacts and the maximum WEPL deviation in phantom images from −19.1 to −0.4 mm. However, the CT numbers cannot be retrieved using iMAR for periprosthetic bone materials, eventually leading to a WEPL deviation of −3.6 mm. The use of iMAR improved large discrepancies in DVHs of PTVs and the gamma index between FBP and GT images but increased the difference in the bladder DVH for bilateral hip prostheses due to newly introduced artifacts. In the patient study, the discrepancies of dose distribution were small on iMAR images when compared with FBP images for most cases, except for two sarcoma cases where gamma analysis failed and dose coverage in 98% of the PTV maximally reduced due to large volume of dark metal artifacts. iMAR reduced the metal artifacts and improved dose distribution accuracy in carbon ion radiotherapy for pelvic cancer. However, the residual and newly introduced artifacts, especially with bilateral hip prostheses, may potentially increase WEPL inaccuracy and dose uncertainty. The use of iMAR has the potential to improve carbon ion treatment planning of pelvic cancer but should be used with caution.

中文翻译：

---

使用商业金属伪影减少工具在髋关节假体患者的碳离子治疗中的剂量影响

该研究调查了迭代金属伪影减少 (iMAR) 工具对装有髋关节假体的盆腔癌患者的碳离子治疗的剂量学影响。具有单侧和双侧髋关节假体的拟人骨盆模型用于模拟具有金属植入物的盆腔癌患者。从体模 CT 扫描获得的原始数据用常规滤波反投影 (FBP) 算法重建，然后用 iMAR 校正。没有髋关节假体的体模也被扫描并用作参考地面实况 (GT)。3例前列腺和4例单侧髋关节假体肉瘤患者的CT图像也通过FBP和iMAR算法重建并比较。iMAR 算法将幻像图像中的金属伪影和最大 WEPL 偏差从 -19.1 毫米减少到 -0.4 毫米。然而，对于假体周围骨材料，无法使用 iMAR 检索 CT 编号，最终导致 WEPL 偏差为 -3.6 mm。iMAR 的使用改善了 PTV 的 DVH 以及 FBP 和 GT 图像之间的伽马指数的巨大差异，但由于新引入的伪影增加了双侧髋关节假体膀胱 DVH 的差异。在患者研究中，与 FBP 图像相比，iMAR 图像在大多数情况下的剂量分布差异很小，除了两个肉瘤病例，伽玛分析失败，98% 的 PTV 中的剂量覆盖由于大量黑暗而最大限度地减少金属制品。iMAR 减少了金属伪影，提高了盆腔癌碳离子放射治疗的剂量分布准确性。然而，残留的和新引入的伪影，尤其是双侧髋关节假体，可能会增加 WEPL 的不准确性和剂量的不确定性。iMAR 的使用有可能改善盆腔癌的碳离子治疗计划，但应谨慎使用。