Enhancement of survival of 9L gliosarcoma bearing rats following intracerebral delivery of drugs in combination with microbeam radiation therapy

Régnard, Pierrick; Bräuer-Krisch, Elke; Troprés, Irène; Keyriläinen, Jani; Bravin, A.; Duc, Géraldine Le

doi:10.1016/j.ejrad.2008.04.049

Cited by 39 publications

(38 citation statements)

References 16 publications

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“…These can be selectively accumulated within the tumor prior to any irradiation protocol. This idea was first proposed by Dilmanian et al 22 and applied experimentally by Régnard et al 23 The probability of undergoing a photoelectric interaction increases significantly for the energy range of the MRT spectrum and in the presence of high-Z contrast agents. Localized tumor dose enhancement is thus achieved.…”

Section: Introductionmentioning

confidence: 95%

“…43 A cylindrical tumor of 4 mm in height and 4 mm in diameter was placed 6.7 mm from the head surface to mimic the tumor model used in the experiments. 23 The tumor was loaded with different elements in both phantoms: iodine (Z ¼ 53), gadolinium (Z ¼ 64), holmium (Z ¼ 67), erbium (Z ¼ 68), ytterbium (Z ¼ 70), lutetium (Z ¼ 71), hafnium (Z ¼ 72), gold (Z ¼ 79), and thallium (Z ¼ 81). A concentration of 5 mg/ml in the tumor was assessed for each element.…”

Section: Iic Phantom Description and Simulation Detailsmentioning

confidence: 99%

“…Pilot in vivo experiments performed at ESRF showed an important increase in survival time when the tumor was loaded with gadolinium compounds [resulting from the union of Gd with diethylene triamine pentaacetic acid (DTPA)]. 23 Gd concentrations of 5 mg/ml have been reported. 24 Due to the continuous improvement of contrast agent delivery methods and their chemistry, higher achievable concentrations are expected in the near future.…”

Section: Introductionmentioning

confidence: 98%

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Monte Carlo dose enhancement studies in microbeam radiation therapy

Martínez-Rovira¹,

Prezado²

2011

Medical Physics

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The remarkable therapeutic index in microbeam radiation therapy can be further improved by loading the tumor with a high-Z element. This study reports quantitative data on several dosimetric magnitudes in order to find the optimum contrast agent. Although the final choice of the element will also depend on possible cytotoxicity, three elements were found to be worthy of mention: gold, thallium, and lutetium.

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Section: Introductionmentioning

confidence: 95%

Section: Iic Phantom Description and Simulation Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Monte Carlo dose enhancement studies in microbeam radiation therapy

Martínez-Rovira¹,

Prezado²

2011

Medical Physics

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“…To date, there have been no studies that reported the application of AuNPs on the MRT technique. There are also very limited studies on using high Z atoms as radiation enhancer for MRT, and most of those works are based on gadolinium [13,14].…”

Section: Discussionmentioning

confidence: 99%

“…Le Duc et al [13] proposed the use of Gd chelate as dose enhancement agent on rodent brain tumours treated with MRT. Regnard et al [14] followed these studies by undertaking animal study using gadolinium compound in combination with microbeam radiotherapy. Theoretical simulation using Monte Carlo found a relevant increase in the dose deposition in the presence of gadolinium [15].…”

Section: Introductionmentioning

confidence: 98%

Influence of Gold Nanoparticles on Radiation Dose Enhancement and Cellular Migration in Microbeam-Irradiated Cells

et al. 2011

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The focus of this research was the enhancement of radiation dose for microbeam radiotherapy (MRT) by the inclusion of gold nanoparticles (AuNPs) in the target. Microbeam radiotherapy is a technique that employs a very high dose rate of X-rays to kill highly resistant tumours such as glioma without jeopardizing the tolerance of normal tissue. The reduction of radiation dose rate used in this technique by using AuNPs may enhance the normal tissue tolerance while achieving better tumour control. In this study, microbeam kilovoltage X-ray of mean energy 125 keV from the SPring8 Synchrotron in Japan was used. The results show dose enhancement effects on endothelial cells by AuNPs which are consistent with previously documented results using broad beams of X-rays. It was also observed in this study that the inclusion of AuNPs accelerates cell migration towards the eradicated area which is important in normal tissue recovery. The phenomenon of cell migration is observed when cell fill depleted gaps that have been created by the microbeams or when such gaps are manually made by scratching the cell culture as a wound. The reason behind this acceleration of the rate of gap fillings is not well understood. However, it has been attributed to various biological processes and has also been thought of as being partially due to the effects of electrostatic charge of such particles. It could also be the combined effects of biological and electrostatic effects due to the charges of the particles inside the cells. Moreover, it is also observed that the cancerous glioma cell fills the gaps in much slower rates in comparison to the normal endothelial cells. This is consistent with the notion on which the MRT techniques are based.

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A novel calorimeter for synchrotron produced monochromatic x‐ray beams

2023

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BackgroundElectron synchrotrons produce x‐ray beams with dose rates orders of magnitude greater than conventional x‐ray tubes and with beam sizes on the order of a few millimeters. These characteristics put severe challenges on current dosimeters to accurately realize absorbed dose or air kerma.PurposeThis work seeks to investigate the suitability of a novel aluminum‐based calorimeter to determine absorbed dose to water with an uncertainty significantly smaller than currently possible with conventional detectors. A lower uncertainty in the determination of absolute dose rate would impact both therapeutic applications of synchrotron‐produced x‐ray beams and research investigations.MethodsA vacuum‐based calorimeter prototype with an aluminum core was built, matching the beam profile of the 140 keV monochromatic x‐ray beam, produced by the Canadian Light Source Biomedical Imaging and Therapy beamline. The choice of material and overall calorimeter design was optimized using FEM thermal modeling software while Monte Carlo radiation transport simulations were used to model the impact of interactions of the radiation beam with the detector components.ResultsCorrections for both the thermal conduction and radiation transport effects were of the order of 3% and the simplicity of the geometry, combined with the monochromatic nature of the incident x‐ray beam, meant that the uncertainty in each correction was ≤0.5%. The calorimeter performance was found to be repeatable over multiple irradiations of 1 Gy at the ± 0.6% level, and no systematic dependence on environmental effects or total dose was observed.ConclusionThe combined standard uncertainty in the determination of absorbed dose to aluminum was estimated to be 0.8%, indicating that absorbed dose to water, the ultimate quantity of interest, could be determined with an uncertainty on the order of 1%. This value is an improvement over current techniques used for synchrotron dosimetry and comparable with the state‐of‐the art for conventional kV x‐ray dosimetry.

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Enhancement of survival of 9L gliosarcoma bearing rats following intracerebral delivery of drugs in combination with microbeam radiation therapy

Cited by 39 publications

References 16 publications

Monte Carlo dose enhancement studies in microbeam radiation therapy

Monte Carlo dose enhancement studies in microbeam radiation therapy

Influence of Gold Nanoparticles on Radiation Dose Enhancement and Cellular Migration in Microbeam-Irradiated Cells

A novel calorimeter for synchrotron produced monochromatic x‐ray beams

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