Purpose

The use of ocular plaques is a promising treatment option for eye melanoma brachytherapy. Although several studies have been done on various ocular plaques, little is known about the dose characterization of ¹⁹⁸Au plaque.

Materials and method

The full mathematical model of the eye phantom, tumor, ¹⁰⁶Ru/¹⁰⁶Rh CCA, and ¹⁹⁸Au plaque were simulated using the Monte Carlo MCNPX code. The dose distribution was measured in the plaque's central axis direction, and a dose profile was also measured at a distance of 2.5 mm from the plaque surface.

Results

The findings showed that ¹⁹⁸Au plaque has superior dosimetric characteristics than CCA plaque for tumors with a thickness of greater than 3.5 mm, while CCA plaque is better for tumors with a thickness of less than 3.5 mm. The dose to the sclera and choroid is higher in the case of CCA plaque, while the dose to the organs at risk (lens and optic nerve) is greater in the case of ¹⁹⁸Au applicator. In the case of ¹⁹⁸Au plaque, however, the dose to sensitive organs was within their permissible dose range.

Conclusion

In the treatment of medium and large tumors, ¹⁹⁸Au plaque is more successful than CCA plaque. It can produce a much more homogeneous lateral dose profile in the target. In the treatment of dome-shaped tumors, ¹⁹⁸Au plaque may be more successful than CCA plaque. As a result, the tumor's shape influences the plaque type selection.

中文翻译：

---

Au-198 眼近距离放射治疗应用器的剂量特征：蒙特卡洛研究

目的

眼部斑块的使用是眼部黑色素瘤近距离放射治疗的一种有前途的治疗选择。^{尽管已经对各种眼斑进行了几项研究，但对198} Au 斑的剂量表征知之甚少。

材料和方法

眼睛模型、肿瘤、¹⁰⁶ Ru/ ¹⁰⁶ Rh CCA 和¹⁹⁸ Au 斑块的完整数学模型使用 Monte Carlo MCNPX 代码进行了模拟。在斑块的中心轴方向测量剂量分布，并且还在距斑块表面2.5mm的距离处测量剂量分布。

结果

研究结果表明，对于厚度大于 3.5 mm 的肿瘤， ¹⁹⁸ Au 斑块具有优于 CCA 斑块的剂量学特征，而对于厚度小于 3.5 mm 的肿瘤，CCA 斑块具有更好的剂量学特征。^{在 CCA 斑块的情况下，巩膜和脉络膜的剂量较高，而在198} Au 涂药器的情况下，危险器官（晶状体和视神经）的剂量较大。^{然而，在198} Au 斑块的情况下，敏感器官的剂量在其允许的剂量范围内。

结论

在中大型肿瘤的治疗中，¹⁹⁸ Au斑块比CCA斑块更成功。它可以在目标中产生更均匀的横向剂量分布。在圆顶状肿瘤的治疗中，¹⁹⁸ Au斑块可能比CCA斑块更成功。因此，肿瘤的形状会影响斑块类型的选择。