Faculty of Science and Engineering, Waseda University, Japan.
Kobe Proton Center, Japan.
Phys Med. 2024 Nov;127:104847. doi: 10.1016/j.ejmp.2024.104847. Epub 2024 Oct 28.
Prompt gammas imaging (PGI) is a promising method for observing a beam's shape and estimating the range of the beam from outside a subject. However 2-dimensional images of prompt gammas (PGs) during irradiation of protons were still difficult to measure. To achieve PGI, we developed a new gamma camera and imaged PGs while irradiating a phantom by proton beams. We also simultaneously measured prompt X-ray (PX) images with an X-ray camera from opposed direction and compared the images. The developed gamma camera uses a 10 mm thick GAGG block optically coupled to a flat panel photomultiplier tube (FP-PMT), and it is contained in a 20 mm thick tungsten container with a pinhole collimator attached. A poly-methyl-methacrylate (PMMA) block was irradiated by proton beams with total number of the protons similar to the clinical level, and the gamma camera imaged PGs and X-ray camera imaged PXs simultaneously. For all of the tested beams, we could measure the beam shapes of the PGs and the PXs and the ranges could also be estimated from the images. For both PG and PX images, time sequential images and accumulated images could be derived. We confirmed that the PGI using our developed gamma camera, as well as PXI, is promising for beam imaging and range estimation in proton therapy.
提示伽马成像（PGI）是一种观察光束形状并从受检者外部估算光束射程的有前途的方法。然而，在质子辐照期间，提示伽马（PG）的二维图像仍然难以测量。为了实现 PGI，我们开发了一种新的伽马相机，并通过质子束辐照体模来对 PG 进行成像。我们还同时使用对向的 X 射线相机测量了提示 X 射线（PX）图像，并对这些图像进行了比较。所开发的伽马相机使用 10 毫米厚的 GAGG 块与平板光电倍增管（FP-PMT）光学耦合，并用附有针孔准直器的 20 毫米厚的钨容器进行封装。将一块聚甲基丙烯酸甲酯（PMMA）块用类似于临床水平的质子总数进行辐照，伽马相机同时对 PG 进行成像，X 射线相机对 PX 进行成像。对于所有测试的光束，我们都可以测量 PG 和 PX 的光束形状，并且可以根据图像估计射程。对于 PG 和 PX 图像，都可以得出时间序列图像和累积图像。我们证实，使用我们开发的伽马相机进行的 PGI 以及 PXI 非常有希望用于质子治疗中的光束成像和射程估计。
