Quantification of Nanoscale Dose Enhancement in Gold Nanoparticle-Aided External Photon Beam Radiotherapy

Secondary electron dynamics in core-shell-satellite nanoparticles: a computational strategy for targeted cancer treatment

As the global incidence of cancer escalates, there exists an urgent necessity for innovative therapeutic modalities. While radiation therapy is indispensable in oncology, it faces significant challenges in achieving an optimal equilibrium between tumour ablation and the preservation of surrounding healthy tissues. Noteworthy advancements such as intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) have enhanced the precision of treatment; however, their efficacy is still constrained by the accuracy of tumour delineation. The utilization of radiosensitizers, with a particular emphasis on metal nanoparticles, presents a promising avenue for augmenting the susceptibility of neoplastic cells to ionizing radiation. This research examines the potential of core-shell-satellite Fe3O4-SiO2-Au nanoparticles as effective radiosensitizers. By investigating the interaction of individual nanoparticles situated within a water phantom of 20 micrometers in diameter with monochromatic photon beams at energies of 50, 100, and 150 keV, we analyse how variations in the structural composition of Au nanoparticles and their concentrations within these multifaceted nanoparticles influence the efficacy of radiation therapy, employing Monte Carlo simulations corroborated by the general-purpose radiation transport code PHITS. Our investigation aspires to refine nanoparticle-based methodologies to enhance cancer treatment outcomes, potentially facilitating the development of more targeted therapeutic interventions that minimize adverse effects while improving patient survival rates.

The Emerging Role of Nanoparticles Combined with Either Radiotherapy or Hyperthermia in Head and Neck Cancer: A Current Review

Head and neck cancer (HNC) includes various malignancies and represents the seventh most common cancer worldwide. The early diagnosis of HNC results in a 70-90% five-year survival rate, which declines with locally advanced stages of disease. Current care employs a multimodal strategy encompassing surgery, radiation therapy (RT), chemotherapy, and immunotherapy, while treatment options vary according to the stage, tumor features, and patient characteristics. About 75% of patients with HNC will benefit from RT, either as a primary treatment or as adjuvant therapy following surgical resection. Technological improvements in RT, such as intensity-modulated RT (IMRT) and image-guided RT (IGRT), have enhanced tumor targeting and minimized adjacent healthy tissue irradiation while also expanding RT to the recurrent or metastatic setting. Innovative therapeutic strategies for HNC integrate RT with immunotherapy, gene therapy, molecular targeted therapy, photodynamic therapy, photothermal therapy, and nanoparticles (NPs), with the objective of optimizing tumor control while reducing damage to normal tissues. NPs are emerging as possible radiosensitizers in HNC treatment, enhancing the efficacy of RT, chemotherapy, and immunotherapy. In vivo and in vitro studies on the irradiation of tumors containing gold (Au), gadolinium (Gd), and hafnium oxide (HfO2) NPs show promising results in enhancing tumor destruction and survival rates, indicating their potential for clinical application. Hyperthermia, investigated as an adjunct treatment, potentially improves outcomes when combined with RT or chemotherapy, with advancements in nanotechnology renewing interest in this approach in HNC. At present, NBTXR3 is the sole NP that is being investigated in clinical trials for the enhancement of HNC RT.

XMEA: A New Hybrid Diamond Multielectrode Array for the In Situ Assessment of the Radiation Dose Enhancement by Nanoparticles

This work presents a novel multielectrode array (MEA) to quantitatively assess the dose enhancement factor (DEF) produced in a medium by embedded nanoparticles. The MEA has 16 nanocrystalline diamond electrodes (in a cell-culture well), and a single-crystal diamond divided into four quadrants for X-ray dosimetry. DEF was assessed in water solutions with up to a 1000 µg/mL concentration of silver, platinum, and gold nanoparticles. The X-ray detectors showed a linear response to radiation dose (r2 ≥ 0.9999). Overall, platinum and gold nanoparticles produced a dose enhancement in the medium (maximum of 1.9 and 3.1, respectively), while silver nanoparticles produced a shielding effect (maximum of 37%), lowering the dose in the medium. This work shows that the novel MEA can be a useful tool in the quantitative assessment of radiation dose enhancement due to nanoparticles. Together with its suitability for cells' exocytosis studies, it proves to be a highly versatile device for several applications.

Nanoparticle-Mediated Radiotherapy: Unraveling Dose Enhancement and Apoptotic Responses in Cancer and Normal Cell Lines

Cervical cancer remains a pressing global health concern, necessitating advanced therapeutic strategies. Radiotherapy, a fundamental treatment modality, has faced challenges such as targeted dose deposition and radiation exposure to healthy tissues, limiting optimal outcomes. To address these hurdles, nanomaterials, specifically gold nanoparticles (AuNPs), have emerged as a promising avenue. This study delves into the realm of cervical cancer radiotherapy through the meticulous exploration of AuNPs' impact. Utilizing ex vivo experiments involving cell lines, this research dissected intricate radiobiological interactions. Detailed scrutiny of cell survival curves, dose enhancement factors (DEFs), and apoptosis in both cancer and normal cervical cells revealed profound insights. The outcomes showcased the substantial enhancement of radiation responses in cancer cells following AuNP treatment, resulting in heightened cell death and apoptotic levels. Significantly, the most pronounced effects were observed 24 h post-irradiation, emphasizing the pivotal role of timing in AuNPs' efficacy. Importantly, AuNPs exhibited targeted precision, selectively impacting cancer cells while preserving normal cells. This study illuminates the potential of AuNPs as potent radiosensitizers in cervical cancer therapy, offering a tailored and efficient approach. Through meticulous ex vivo experimentation, this research expands our comprehension of the complex dynamics between AuNPs and cells, laying the foundation for their optimized clinical utilization.

A Boom in Nanotechnologies for a High Level of Precision Medicine

The number of publications on nanomedicine in oncology has been exponential over the last ten years, going from 640 publications in 2012 to 2487 publications in 2022, reflecting the growing interest and potential of these new technologies [...].

Emerging plasmonic nanoparticles and their assemblies for cancer radiotherapy

Plasmonic nanoparticles and their assemblies have been widely used in biosensing, optical imaging, and biomedicine over the past few decades. Especially in the field of radiotherapy, the physicochemical properties of high-Z plasmonic nanomaterials endow them with the ability to sensitize radiotherapy. Compared with single particles, the assembled structure with tunable properties leads to versatile applications in drug delivery and cancer treatment. In this review, we focus on plasmonic nanoparticles and their assemblies for cancer radiotherapy. First, the sensitization mechanism of plasmonic radiosensitizers is briefly introduced. Subsequently, the recent progress in cancer radiotherapy is systematically discussed according to the structure and shape classification. Finally, the current challenges and future perspectives in this field are also discussed in detail.

Dosimetric Impact on the Flattening Filter and Addition of Gold Nanoparticles in Radiotherapy: A Monte Carlo Study on Depth Dose Using the 6 and 10 MV FFF Photon Beams

PURPOSE

This phantom study investigated through Monte Carlo simulation how the dose enhancement varied with depth, when gold nanoparticles (NPs) were added using the flattening filter-free (FFF) photon beams in gold NP-enhanced radiotherapy.

METHOD

A phantom with materials varying from pure water to a mixture of water and gold NPs at different concentrations (3-40 mg/mL) were irradiated by the 6 and 10 MV flattening filter (FF) and FFF photon beams. Monte Carlo simulations were carried out to determine the depth doses along the central beam axis of the phantom up to a depth of 40 cm. The dose enhancement ratio (DER) and FFF enhancement ratio (FFFER) were calculated based on the Monte Carlo results.

RESULTS

The DER values were found decreased with an increase of depth and increase of NP concentration in the phantom. For the maximum NP concentration of 40 mg/mL, the DER values decreased 6.9, 12, 4.6 and 7.2% at a phantom depth from 2 to 40 cm, using the 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF photon beams, respectively. The maximum DER values for the 6 MV beams were 1.08 (FF) and 1.14 (FFF), while those for the 10 MV beams were 1.04 (FF) and 1.07 (FFF). When the FF was removed from the linear accelerator head, the FFFER showed a more significant increase of dose enhancement for the 6 MV beams (1.057) than the 10 MV (1.031).

CONCLUSION

From the DER and FFFER values based on the Monte Carlo results, it is concluded that the dose enhancement with depth was dependent on the NP and beam variables, namely, NP concentration, presence of FF in the beam and beam energy. Dose enhancement was more significant when using the lower photon beam energy (i.e., 6 MV), FFF photon beam and higher NP concentration in the study.

The OpenGATE ecosystem for Monte Carlo simulation in medical physics

This paper reviews the ecosystem of GATE, an open-source Monte Carlo toolkit for medical physics. Based on the shoulders of Geant4, the principal modules (geometry, physics, scorers) are described with brief descriptions of some key concepts (Volume, Actors, Digitizer). The main source code repositories are detailed together with the automated compilation and tests processes (Continuous Integration). We then described how the OpenGATE collaboration managed the collaborative development of about one hundred developers during almost 20 years. The impact of GATE on medical physics and cancer research is then summarized, and examples of a few key applications are given. Finally, future development perspectives are indicated.