Faculty of Science and Engineering, Waseda University, Japan.
Cyclotron and Radioisotope Center, Tohoku University, Japan.
Phys Med Biol. 2024 Feb 22;69(5). doi: 10.1088/1361-6560/ad25c6.
. Prompt gamma photon, prompt x-ray, and induced positron imaging are possible methods for observing a proton beam's shape from outside the subject. However, since these three types of images have not been measured simultaneously nor compared using the same subject, their advantages and disadvantages remain unknown for imaging beam shapes in therapy. To clarify these points, we developed a triple-imaging-modality system to simultaneously measure prompt gamma photons, prompt x-rays, and induced positrons during proton beam irradiation to a phantom.. The developed triple-imaging-modality system consists of a gamma camera, an x-ray camera, and a dual-head positron emission tomography (PET) system. During 80 MeV proton beam irradiation to a polymethyl methacrylate (PMMA) phantom, imaging of prompt gamma photons was conducted by the developed gamma camera from one side of the phantom. Imaging of prompt x-rays was conducted by the developed x-ray camera from the other side. Induced positrons were measured by the developed dual-head PET system set on the upper and lower sides of the phantom.. With the proposed triple-imaging-modality system, we could simultaneously image the prompt gamma photons and prompt x-rays during proton beam irradiation. Induced positron distributions could be measured after the irradiation by the PET system and the gamma camera. Among these imaging modalities, image quality was the best for the induced positrons measured by PET. The estimated ranges were actually similar to those imaged with prompt gamma photons, prompt x-rays and induced positrons measured by PET.. The developed triple-imaging-modality system made possible to simultaneously measure the three different beam images. The system will contribute to increasing the data available for imaging in therapy and will contribute to better estimating the shapes or ranges of proton beam.
. 从受检体外部观察质子束形状，可以采用瞬时伽马光子、瞬时 X 射线和感生正电子成像等方法。但是，这三种类型的图像尚未在同一受检体上同时测量和比较，因此，它们在治疗中的束流成像方面的优缺点尚不清楚。为了阐明这些问题，我们开发了一种三重成像模式系统，以便在质子束辐照到体模时同时测量瞬时伽马光子、瞬时 X 射线和感生正电子。. 所开发的三重成像模式系统由伽马相机、X 射线相机和双探头正电子发射断层扫描（PET）系统组成。在 80 MeV 质子束辐照到聚甲基丙烯酸甲酯（PMMA）体模时，通过开发的伽马相机从体模的一侧进行瞬时伽马光子成像。通过开发的 X 射线相机从另一侧进行瞬时 X 射线成像。通过设置在体模上下两侧的开发的双探头 PET 系统测量感生正电子。. 使用所提出的三重成像模式系统，我们可以在质子束辐照期间同时对瞬时伽马光子和瞬时 X 射线进行成像。通过 PET 系统和伽马相机可以在辐照后测量感生正电子的分布。在这些成像模式中，通过 PET 测量的感生正电子的图像质量最好。估计的范围实际上与通过瞬时伽马光子、瞬时 X 射线和通过 PET 测量的感生正电子成像的范围相似。. 所开发的三重成像模式系统能够同时测量三种不同的束流图像。该系统将有助于增加治疗中的成像数据，并有助于更好地估计质子束的形状或范围。
