Discipline of Medical Radiations, The Royal Melbourne Institute of Technology University, Victoria, Australia.
Int J Radiat Oncol Biol Phys. 2012 Nov 15;84(4):e549-55. doi: 10.1016/j.ijrobp.2012.05.029. Epub 2012 Jul 3.
Gold nanoparticles (AuNps), because of their high atomic number (Z), have been demonstrated to absorb low-energy X-rays preferentially, compared with tissue, and may be used to achieve localized radiation dose enhancement in tumors. The purpose of this study is to introduce the first example of a novel multicompartment radiochromic radiation dosimeter and to demonstrate its applicability for 3-dimensional (3D) dosimetry of nanoparticle-enhanced radiation therapy.
A novel multicompartment phantom radiochromic dosimeter was developed. It was designed and formulated to mimic a tumor loaded with AuNps (50 nm in diameter) at a concentration of 0.5 mM, surrounded by normal tissues. The novel dosimeter is referred to as the Sensitivity Modulated Advanced Radiation Therapy (SMART) dosimeter. The dosimeters were irradiated with 100-kV and 6-MV X-ray energies. Dose enhancement produced from the interaction of X-rays with AuNps was calculated using spectrophotometric and cone-beam optical computed tomography scanning by quantitatively comparing the change in optical density and 3D datasets of the dosimetric measurements between the tissue-equivalent (TE) and TE/AuNps compartments. The interbatch and intrabatch variability and the postresponse stability of the dosimeters with AuNps were also assessed.
Radiation dose enhancement factors of 1.77 and 1.11 were obtained using 100-kV and 6-MV X-ray energies, respectively. The results of this study are in good agreement with previous observations; however, for the first time we provide direct experimental confirmation and 3D visualization of the radiosensitization effect of AuNps. The dosimeters with AuNps showed small (<3.5%) interbatch variability and negligible (<0.5%) intrabatch variability.
The SMART dosimeter yields experimental insights concerning the spatial distributions and elevated dose in nanoparticle-enhanced radiation therapy, which cannot be performed using any of the current methods. The authors concluded that it can be used as a novel independent method for nanoparticle-enhanced radiation therapy dosimetry.
金纳米粒子（AuNps）由于其高原子序数（Z），与组织相比，已被证明优先吸收低能 X 射线，并可用于实现肿瘤内的局部辐射剂量增强。本研究的目的是介绍新型多隔室放射变色辐射剂量计的第一个实例，并证明其在纳米颗粒增强放射治疗的 3 维（3D）剂量测定中的适用性。
开发了一种新型多隔室幻影放射变色剂量计。它的设计和配方旨在模拟充满浓度为 0.5mM 的 50nm 金纳米粒子的肿瘤，周围是正常组织。新型剂量计称为灵敏度调制先进放射治疗（SMART）剂量计。用 100kV 和 6MV X 射线能量对剂量计进行照射。通过定量比较等效组织（TE）和 TE/AuNps 隔室之间的光密度和 3D 数据集的变化，使用分光光度法和锥形束光学计算机断层扫描来计算 X 射线与 AuNps 相互作用产生的剂量增强。还评估了含有 AuNps 的剂量计的批间和批内变异性以及后反应稳定性。
分别用 100kV 和 6MV X 射线能量获得 1.77 和 1.11 的辐射剂量增强因子。本研究结果与以前的观察结果一致；然而，我们首次提供了 AuNps 放射增敏效应的直接实验证实和 3D 可视化。含有 AuNps 的剂量计的批间变异性较小（<3.5%），批内变异性可以忽略（<0.5%）。
SMART 剂量计提供了关于纳米颗粒增强放射治疗中空间分布和升高剂量的实验见解，这是任何当前方法都无法实现的。作者得出结论，它可以用作纳米颗粒增强放射治疗剂量测定的新独立方法。
