Department of Medical Physics, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy.
Nuclear Medicine Unit, IRCCS Azienda Ospedaliero, University of Bologna, 40138 Bologna, Italy.
Phys Med. 2022 Jun;98:98-112. doi: 10.1016/j.ejmp.2022.04.017. Epub 2022 May 5.
In Selective Internal Radiation Therapy (SIRT), Y is administered to primary/secondary hepatic lesions. An accurate pre-treatment planning using Tc-MAA SPECT/CT allows the assessment of its feasibility and of the activity to be injected. Unfortunately, SPECT/CT suffers from patient-specific respiratory motion which causes artifacts and absorbed dose inaccuracies. In this study, a data-driven solution was developed to correct the respiratory motion.
The tool realigns the barycenter of SPECT projection images and shifts them to obtain a fine registration with the attenuation map. The tool was validated using a modified dynamic phantom with several breathing patterns. We compared the absorbed dose distributions derived from uncorrected(D)/corrected(D) images with static ones(D) in terms of γ-passing rates, 210 Gy isodose volumes, dose-volume histograms and percentage differences of mean doses (i.e., ΔD¯ and ΔD¯, respectively). The tool was applied to twelve SIRT patients and the Bland-Altman analysis was performed on mean doses.
In the phantom study, the agreement between D and D was higher (γ-passing rates generally > 90%) than D and D. The isodose volumes in D were closer than D to D, with differences up to 10% and 30% respectively. A reduction from a median ΔD¯ = -19.3% to ΔD¯ = -0.9%, from ΔD¯ = -42.8% to ΔD¯ = -7.0% and from ΔD¯ = 1586% to ΔD¯ = 47.2% was observed in liver-, tumor- and lungs-like structures. The Bland-Altman analysis on patients showed variations (±50 Gy) and (±4 Gy) between D¯ and D¯ of tumor and lungs, respectively.
The proposed tool allowed the correction of Tc-MAA SPECT/CT images, improving the accuracy of the absorbed dose distribution.
在选择性内部放射疗法（SIRT）中，放射性同位素 Y 被施用于原发性/继发性肝脏病变。使用 Tc-MAA SPECT/CT 进行准确的术前规划可以评估其可行性和要注射的放射性同位素 Y 的活度。不幸的是，SPECT/CT 受到患者特定的呼吸运动的影响，这会导致伪影和吸收剂量不准确。在这项研究中，开发了一种数据驱动的解决方案来校正呼吸运动。
该工具重新调整 SPECT 投影图像的质心并对其进行移位，以实现与衰减图的精细配准。该工具使用具有几种呼吸模式的改良动态体模进行了验证。我们比较了未校正（D）/校正（D）图像与静态（D）图像的吸收剂量分布，比较指标包括 γ 通过率、210 Gy 等剂量体积、剂量-体积直方图和平均剂量的百分比差异（即，ΔD¯ 和 ΔD¯，分别）。该工具应用于 12 例 SIRT 患者，对平均剂量进行 Bland-Altman 分析。
在体模研究中，D 与 D 的一致性较高（γ 通过率通常>90%），优于 D 与 D。D 中的等剂量体积比 D 更接近 D，差异最大可达 10%和 30%。在肝脏、肿瘤和肺样结构中，分别观察到从中位数ΔD¯=-19.3%到ΔD¯=-0.9%、从ΔD¯=-42.8%到ΔD¯=-7.0%和从ΔD¯=1586%到ΔD¯=47.2%的减少。对患者的 Bland-Altman 分析显示，肿瘤和肺部的 D¯和 D¯ 之间存在差异（±50 Gy）和（±4 Gy）。
提出的工具允许校正 Tc-MAA SPECT/CT 图像，提高吸收剂量分布的准确性。
