A projection-domain low-count quantitative SPECT method for alpha-particle emitting radiopharmaceutical therapy
Zekun Li, Nadia Benabdallah, Diane S. Abou, Brian C. Baumann, Farrokh Dehdashti, David H. Ballard, Jonathan Liu, Uday Jammalamadaka, Richard Laforest, Richard L… 展开作者
Zekun Li, Nadia Benabdallah, Diane S. Abou, Brian C. Baumann, Farrokh Dehdashti, David H. Ballard, Jonathan Liu, Uday Jammalamadaka, Richard Laforest, Richard L. Wahl, Daniel L. J. Thorek, Abhinav K. Jha
Single-photon emission computed tomography (SPECT) provides a mechanism to estimate regional isotope uptake in lesions and at-risk organs after administration of α-particle-emitting radiopharmaceutical therapies (α-RPTs). However, this estimation task is challenging due to the complex emission spectra, the very low number of detected counts, the impact of stray-radiation-related noise at these low counts, and the multiple image-degrading processes in SPECT. The conventional reconstruction-based quantification methods are observed to be erroneous for α-RPT SPECT. To address these challenges, we developed a low-count quantitative SPECT (LC-QSPECT) method that directly estimates the regional activity uptake from the projection data, compensates for stray-radiation-related noise, and for the radioisotope and SPECT physics. The method was validated in the context of three-dimensional SPECT with 223 Ra. Validation was performed using both realistic simulation studies, including a virtual clinical trial, and synthetic and anthropomorphic physical-phantom studies. Across all studies, the LC-QSPECT method yielded reliable regional-uptake estimates and outperformed the conventional ordered subset expectation maximization (OSEM)-based reconstruction and geometric transfer matrix (GTM)-based post-reconstruction partial-volume compensation methods. Further, the method yielded reliable uptake across different lesion sizes, contrasts, and different levels of intra-lesion heterogeneity. Additionally, the variance of the estimated uptake approached the Cramé-Rao bound-defined theoretical limit.
Artificial intelligence for simplified patient-centered dosimetry in radiopharmaceutical therapies
Bern University Hospital, University of Bern（伯尔尼大学医院，伯尔尼大学）；BC Cancer Research（不列颠哥伦比亚省癌症研究中心）；Geneva University Hospital（日内瓦大学医院）；University of British Columbia（不列颠哥伦比亚大学）
Towards Routine AI-Based PET/CT and SPECT/CT Lesion Segmentation and Tracking in PSMA Theranostics
BC Cancer Research Institute（BC癌症研究所）；University of British Columbia（不列颠哥伦比亚大学）；Université Laval（拉瓦尔大学）；CHU de Québec - Université Laval Research Centre（魁北克大学医院研究中心-拉瓦尔大学）；CHU de Québec – Université Laval（魁北克大学医院-拉瓦尔大学）
Secondary radiation measurements for particle therapy applications: Charged secondaries produced by 4He and 12C ion beams in a PMMA target at large angle
Optimization of the image contrast in SPECT-CT bremsstrahlung imaging for Selective Internal Radiation Therapy of liver malignancies with Y-90 microspheres
Integrating microdosimetric in vitro RBE models for particle therapy into TOPAS MC using the MicrOdosimetry-based modeling for RBE Assessment (MONAS) tool
Analytical expressions for stopping-power ratios relevant for accurate dosimetry in particle therapy
在粒子治疗中，精确的电离室剂量测定需要了解离子束对空气和水的停止功率比（STPR）。早期的工作已经研究了原始碳离子束的STPR，但在这里，我们将计算扩展到离子范围（1 <= z <= 18）以及分散布拉格峰（SOBP），并提供了一个理论上的深入研究，特别关注与粒子治疗相关的参数机制。蒙特卡罗输运程序SHIELD-HIT用于计算根据国际原子能机构（IAEA）的建议确定STPR所需的完整粒子注量谱。我们确认，STPR主要取决于当前的离子的能量，而不是他们的电荷z或在介质中的绝对位置。然而，STPR为不同的停止功率数据的水和空气的国际辐射单位与测量委员会（ICRU）建议的比较，包括最近修订的数据水，在高原地区产生的偏差高达2%。相比之下，二次粒子谱对STPR的影响在整个区域内直到实际范围都要小两个数量级。所获得的见解，使我们能够提出一个解析近似的STPR为原始和SOBPs作为穿透深度的函数，参数仅依赖于初始能量和离子的残留范围，分别。
A new method using machine learning to integrate ECG and gated SPECT MPI for Cardiac Resynchronization Therapy Decision Support on behalf of the VISION-CRT
Bragg-Curve Simulation of Carbon-Ion Beams for Particle-therapy Applications: a study with the GEANT4 toolkit
我们使用GEANT4 Monte Carlo MC Toolkit模拟碳离子束入射到水、组织和骨骼上，同时考虑到核碎裂反应。在增加初级射束的能量时，布拉格峰的位置转移到体模内部更深的位置。对于不同的材料，峰值位于沿束方向的较浅的深度处，并且随着电子密度NZ的增加而变得尖锐。随后，产生的深度剂量的布拉格曲线，然后基准与德国GSI的实验数据。计算结果与GSI实验数据具有较好的相关性，精度在0.02~0.08cm之间，为在重离子治疗计划中采用MC奠定了基础。Kolmogorov-Smirnov K-S检验从统计学的角度进一步确定了模拟数据与实验测量数据非常匹配。将入口处的二维等剂量线与峰值位置周围和超出峰值的尾部区域中的等剂量线进行比较，表明由于二次剂量，与水和组织相比，骨产生更多剂量。在水中，结果表明，每个碎片沉积的最大能量主要归因于次级碳离子，其次是次级硼和铍。此外，产生的质子数是最高的，从而对尾区的总剂量沉积做出最大贡献。最后分析了中子和光子的关联谱。平均中子能量值为16.29 MeV，次级γ射线为1.03 MeV。然而，中子剂量被认为是可以忽略不计的总剂量相比，由于其较长的范围。
Weighted Directional Total Nuclear Variation for Joint Yttrium-90 PET/SPECT Reconstruction with CTAC-derived Guidance
University College London (UCL)（伦敦大学学院）；The National Physical Laboratory (NPL)（英国国家物理实验室）；Oxford University Hospitals NHS Foundation Trust（牛津大学医院NHS基金会信托）；University of Oxford（牛津大学）；The Christie NHS Trust（克里斯蒂NHS信托）；Centre for Inverse Problems（逆问题中心）
