Department of Physics, Faculty of Science, Ryerson University, 350 Victoria St., Toronto, ON, M5B 2K3, Canada.
Medical Physics Division, Department of Radiation Oncology, Washington University School of Medicine, 660 S Euclid Ave, St Louis, MO, 63110, USA.
Sci Rep. 2020 Aug 7;10(1):13417. doi: 10.1038/s41598-020-70429-9.
This study investigates the photon production from thermal neutron capture in a gadolinium (Gd) infused tumor as a result of secondary neutrons from particle therapy. Gadolinium contrast agents used in MRI are distributed within the tumor volume and can act as neutron capture agents. As a result of particle therapy, secondary neutrons are produced and absorbed by Gd in the tumor providing potential enhanced localized dose in addition to a signature photon spectrum that can be used to produce an image of the Gd enriched tumor. To investigate this imaging application, Monte Carlo (MC) simulations were performed for 10 different particles using a 5-10 cm spread out-Bragg peak (SOBP) centered on an 8 cm, 3 mg/g Gd infused tumor. For a proton beam, 1.9 × 10 neutron captures per RBE weighted Gray Equivalent dose (GyE) occurred within the Gd tumor region. Antiprotons ([Formula: see text]), negative pions (- π), and helium (He) ion beams resulted in 10, 17 and 1.3 times larger Gd neutron captures per GyE than protons, respectively. Therefore, the characteristic photon based spectroscopic imaging and secondary Gd dose enhancement could be viable and likely beneficial for these three particles.
这项研究调查了在粒子治疗中次级中子的作用下，镝（Gd）注入肿瘤中热中子捕获产生的光子。磁共振成像（MRI）中使用的镝造影剂分布在肿瘤体积内，可作为中子捕获剂。由于粒子治疗，次级中子被肿瘤中的 Gd 吸收，除了可以产生富含 Gd 肿瘤图像的特征光子光谱外，还提供了潜在的增强局部剂量。为了研究这种成像应用，使用一个 5-10 cm 扩展布喇格峰（SOBP）对 10 种不同的粒子进行了蒙特卡罗（MC）模拟，该 SOBP 中心位于一个 8 cm、3 mg/g Gd 注入肿瘤上。对于质子束，在 Gd 肿瘤区域内每 RBE 加权等效灰度剂量（GyE）发生 1.9×10 次中子捕获。反质子（[Formula: see text]）、负π介子（-π）和氦（He）离子束分别使 GyE 中 Gd 中子捕获增加了 10、17 和 1.3 倍。因此，基于特征光子的光谱成像和二次 Gd 剂量增强可能对这三种粒子都是可行且有益的。
