使用 Geant4/GATE 的新进展模拟 Lu & I 分子放疗的 SPECT 自动勾画采集。

Modelling SPECT auto-contouring acquisitions for Lu & I molecular radiotherapy using new developments in Geant4/GATE.

机构信息

CRCT, UMR 1037, INSERM, Université Toulouse III Paul Sabatier, Toulouse, France; SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, Mol 2400, Belgium.

CRCT, UMR 1037, INSERM, Université Toulouse III Paul Sabatier, Toulouse, France.

出版信息

Phys Med. 2022 Apr;96:101-113. doi: 10.1016/j.ejmp.2022.03.003. Epub 2022 Mar 8.

DOI:10.1016/j.ejmp.2022.03.003

PMID:35276403

Abstract

PURPOSE

Monte Carlo modelling of SPECT imaging in Molecular Radiotherapy can improve activity quantification. Until now, SPECT modelling with GATE only considered circular orbit (CO) acquisitions. This cannot reproduce auto-contour acquisitions, where the detector head moves close to the patient to improve image resolution. The aim of this work is to develop and validate an auto-contouring step-and-shoot acquisition mode for GATE SPECT modelling.

METHODS

Lu and I SPECT experimental acquisitions performed on a Siemens Symbia T2 and GE Discovery 670 gamma camera, respectively, were modelled. SPECT projections were obtained for a cylindrical Jaszczak phantom and a lung and spine phantom. Detector head parameters (radial positions and acquisition angles) were extracted from the experimental projections to model the non-circular orbit (NCO) detector motion. The gamma camera model was validated against the experimental projections obtained with the cylindrical Jaszczak (Lu) and lung and spine phantom (I). Then, Lu and I CO and NCO SPECT projections were simulated to validate the impact of explicit NCO modelling on simulated projections.

RESULTS

Experimental and simulated SPECT images were compared using the gamma index, and were in good agreement with gamma index passing rate (GIPR) and gamma of 96.27%, 0.242 (Lu) and 92.89%, 0.36 (I). Then, simulated Lu and I CO and NCO SPECT projections were compared. The GIPR, gamma between the two gamma camera motions was 99.85%, 0.108 for Lu and 75.58%, 0.6 for I.

CONCLUSION

This work thereby justifies the need for auto-contouring modelling for isotopes with high septal penetration.

摘要

目的

在分子放射治疗中的单光子发射计算机断层成像（SPECT）的蒙特卡罗建模可以提高活性定量。到目前为止，使用 GATE 的 SPECT 建模仅考虑了圆形轨道（CO）采集。这不能复制自动轮廓采集，在自动轮廓采集中，探测器头靠近患者以提高图像分辨率。这项工作的目的是开发和验证 GATE SPECT 建模的自动轮廓步进和拍摄采集模式。

方法

对分别在西门子 Symbia T2 和 GE Discovery 670 伽马相机上进行的 Lu 和 I SPECT 实验采集进行建模。为圆柱状 Jaszczak 体模和肺和脊柱体模获得了 SPECT 投影。从实验投影中提取探测器头参数（径向位置和采集角度）以模拟非圆形轨道（NCO）探测器运动。伽马相机模型通过与圆柱状 Jaszczak（Lu）和肺和脊柱体模（I）获得的实验投影进行验证。然后，模拟 Lu 和 I CO 和 NCO SPECT 投影以验证显式 NCO 建模对模拟投影的影响。

结果

使用伽马指数比较实验和模拟的 SPECT 图像，并且与伽马指数通过率（GIPR）和伽马值为 96.27%，0.242（Lu）和 92.89%，0.36（I）吻合良好。然后，比较了模拟的 Lu 和 I CO 和 NCO SPECT 投影。两种伽马相机运动之间的 GIPR，伽马值为 99.85%，0.108 为 Lu，75.58%，0.6 为 I。