Organ-specific SPECT activity calibration using 3D printed phantoms for molecular radiotherapy dosimetry.
Organ-specific SPECT activity calibration using 3D printed phantoms for molecular radiotherapy dosimetry.
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DOI：
10.1186/s40658-016-0148-1
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发表时间：
2016-12
期刊：
影响因子：
4
通讯作者：
Snee R
中科院分区：
文献类型：
--
作者：
Robinson AP;Tipping J;Cullen DM;Hamilton D;Brown R;Flynn A;Oldfield C;Page E;Price E;Smith A;Snee R
分子放射治疗的患者特异性吸收剂量计算需要精确的放射性定量。这通常来自单光子发射计算机断层扫描（SPECT）成像，使用校准因子将检测到的计数与体模插入物中的已知活性相关联。基于许多临床剂量计算的数学模型，已经使用3D打印技术生产了一系列体模插入物。体模插入物的SPECT/CT数据已用于计算99 mTc和177 Lu的新器官特异性校准因子。将测量的校准因子与使用高斯核计算的预测值进行比较。3D打印器官的测量SPECT校准因子显示99 mTc和177 Lu对器官形状的明显依赖性。使用基于高斯核的计算，在99 mTc和177 Lu的插入体积的两个数量级变化上再现了所观察到的校准因子的变化。这些新的器官特异性校准因子显示肝脏、脾脏和肾脏的吸收剂量分别减少24%、11%和8%。来自3D打印体模插入物的非球形校准因子可以显着提高分子放射治疗的整个器官活动量化的准确性，为个性化活动量化和患者特定剂量测定提供关键一步。研究发现，3D打印插入物为临床中心提供了一种具有成本效益和效率的方式，以获取更真实的体模数据。
Patient-specific absorbed dose calculations for molecular radiotherapy require accurate activity quantification. This is commonly derived from Single-Photon Emission Computed Tomography (SPECT) imaging using a calibration factor relating detected counts to known activity in a phantom insert. A series of phantom inserts, based on the mathematical models underlying many clinical dosimetry calculations, have been produced using 3D printing techniques. SPECT/CT data for the phantom inserts has been used to calculate new organ-specific calibration factors for 99mTc and 177Lu. The measured calibration factors are compared to predicted values from calculations using a Gaussian kernel. Measured SPECT calibration factors for 3D printed organs display a clear dependence on organ shape for 99mTc and 177Lu. The observed variation in calibration factor is reproduced using Gaussian kernel-based calculation over two orders of magnitude change in insert volume for 99mTc and 177Lu. These new organ-specific calibration factors show a 24, 11 and 8 % reduction in absorbed dose for the liver, spleen and kidneys, respectively. Non-spherical calibration factors from 3D printed phantom inserts can significantly improve the accuracy of whole organ activity quantification for molecular radiotherapy, providing a crucial step towards individualised activity quantification and patient-specific dosimetry. 3D printed inserts are found to provide a cost effective and efficient way for clinical centres to access more realistic phantom data.