Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Medical Physics Unit, Reggio Emilia, Italy; Department of Physics, University of Bologna, Italy.
School of Engineering, Cardiff University, Cardiff, UK.
Phys Med. 2019 Jan;57:153-159. doi: 10.1016/j.ejmp.2018.12.029. Epub 2019 Jan 8.
At present activity quantification is one of the most critical step in dosimetry calculation, and Partial Volume Effect (PVE) one of the most important source of error. In recent years models based upon phantoms that incorporate hot spheres have been used to establish recovery models. In this context the goal of this study was to point out the most critical issues related to PVE and to establish a model closer to a biological imaging environment.
Two different phantoms, filled with a Lu solution, were used to obtain the PVE Recovery Coefficients (RCs): a phantom with spherical inserts and a phantom with organ-shaped inserts. Two additional phantoms with inserts of various geometrical shapes and an anthropomorphic phantom were acquired to compare the real activities to predicted values after PVE correction.
The RCs versus volume of the inserts produced two different curves, one for the spheres and one for the organs. After PVE correction, accuracy on activity quantification averaged over all inserts of three test phantoms passed from -26% to 1.3% (from 26% to 10% for absolute values).
RCs is a simple method for PVE correction easily applicable in clinical routine. The use of two different models for organs and lesions has permitted to closely mimic the situation in a living subject. A marked improvement in the quantification of activity was observed when PVE correction was adopted, even if further investigations should be performed for more accurate models of PVE corrections.
目前，活性量化是剂量计算中最关键的步骤之一，部分容积效应（PVE）是最主要的误差源之一。近年来，基于包含热球的体模的模型已被用于建立恢复模型。在这种情况下，本研究的目的是指出与 PVE 相关的最关键问题，并建立更接近生物成像环境的模型。
使用两个不同的充满 Lu 溶液的体模来获得 PVE 恢复系数（RC）：一个带有球形插入物的体模和一个带有器官形状插入物的体模。获得了两个具有不同几何形状的插入物和一个拟人化体模的两个附加体模，以比较经 PVE 校正后的实际活动与预测值。
插入物体积的 RC 产生了两条不同的曲线，一条用于球体，一条用于器官。经 PVE 校正后，三个测试体模的所有插入物的活性定量准确性从 -26%提高到 1.3%（绝对值从 26%提高到 10%）。
RCs 是一种简单的 PVE 校正方法，易于在临床常规中应用。使用两种不同的器官和病变模型，能够更逼真地模拟活体中的情况。采用 PVE 校正后，观察到活性定量明显改善，尽管需要进一步研究更准确的 PVE 校正模型。
