One of the main limitations during low-kV IORT (intraoperative radiotherapy) with dedicated spherical applicators is the long treatment time. Employing nanoparticles (NPs) can reduce the treatment time through increasing the absorbed dose by the irradiated volume. The current study aims to evaluate and compare the efficacy of different clinically recommended NP types in dose enhancement during low-kV IORT using a Monte Carlo simulation approach.

The INTRABEAM, a dedicated IORT machine, including the bare probe along with 2 and 4 cm diameter spherical applicators was simulated by MCNPX Monte Carlo code and dose enhancement factor (DEF) in presence of eight different NP types of Silver (Ag), Gold (Au), Bismuth (Bi), Iron (Fe), Gadolinium (Gd), Hafnium (Hf), Platinum (Pt), and Titanium (Ti) with two concentrations of 0.5% (5 mg/g) and 2% (20 mg/g) were calculated inside the water.

The results demonstrated that the Bi nanoparticle has the most desirable efficacy in dose enhancement within the target region as well as protection of underlying healthy tissues, especially at 2% concentration. Ag, Au, Hf, and Pt NPs have also a good performance in dose enhancement within the tumor volume, but at expense of higher absorbed dose by underlying healthy tissues.

From the results, it can be concluded that employing the NPs during low energy X-ray IORT can considerably reduce the treatment time, a fact that can increase the lifetime of the IORT machine as well as improve the anesthetized patient manipulation irradiated inside the operating room.

使用专用球形涂药器的低kV IORT（术中放疗）期间的主要限制之一是治疗时间长。使用纳米颗粒（NPs）可以通过增加辐照量来增加吸收剂量，从而减少治疗时间。当前的研究旨在使用蒙特卡罗模拟方法评估和比较不同临床推荐的NP类型在低kV IORT期间剂量增加中的功效。

在8种不同的NP类型的银（Ag），金（ Au），铋（Bi），铁（Fe），d（Gd），Ha（Hf），铂（Pt）和钛（Ti），两种浓度分别为0.5％（5 mg / g）和2％（20在水中计算。

结果表明，Bi纳米颗粒在目标区域内的剂量增加以及对基础健康组织的保护方面具有最理想的功效，尤其是在浓度为2％的情况下。Ag，Au，Hf和Pt NP在肿瘤体积内的剂量增加方面也有良好的表现，但以潜在的健康组织吸收更高的剂量为代价。

从结果可以得出结论，在低能X射线IORT期间使用NP可以显着减少治疗时间，这一事实可以延长IORT机器的使用寿命，并改善在手术室内照射的麻醉患者的操作。