Microbeam radiation therapy

Slatkin, D.N.; Spanne, P.; Dilmanian, F.A.; Sandborg, Michael

doi:10.1118/1.596771

Cited by 269 publications

(232 citation statements)

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“…In microbeam radiation therapy (MRT), the tumor is irradiated by arrays of micrometer wide planar beams of unconventionally high doses of up to a few hundred Grays that are separated by several hundred micrometer wide low dose regions 1 . These treatment fields selectively destroy tumor tissue 2 , 3 , 4 while leaving penetrated healthy tissue unimpaired 5 , 6 .…”

Section: Introductionmentioning

confidence: 99%

A preclinical microbeam facility with a conventional x‐ray tube

et al. 2016

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Purpose:Microbeam radiation therapy is an innovative treatment approach in radiation therapy that uses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar x‐ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors while normal tissue could effectively be spared. However, development and clinical application of microbeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only large synchrotrons provide appropriate beam properties for the production of microbeams.Methods:In this work, a conventional x‐ray tube with a small focal spot and a specially designed collimator are used to produce microbeams for preclinical research. The applicability of the developed source is demonstrated in a pilot in vitro experiment. The properties of the produced radiation field are characterized by radiochromic film dosimetry.Results:50 μm wide and 400 μm spaced microbeams were produced in a 20 × 20 mm2 sized microbeam field. The peak to valley dose ratio ranged from 15.5 to 30, which is comparable to values obtained at synchrotrons. A dose rate of up to 300 mGy/s was achieved in the microbeam peaks. Analysis of DNA double strand repair and cell cycle distribution after in vitro exposures of pancreatic cancer cells (Panc1) at the x‐ray tube and the European Synchrotron leads to similar results. In particular, a reduced G2 cell cycle arrest is observed in cells in the microbeam peak region.Conclusions:At its current stage, the source is restricted to in vitro applications. However, moderate modifications of the setup may soon allow in vivo research in mice and rats.

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Section: Introductionmentioning

confidence: 99%

A preclinical microbeam facility with a conventional x‐ray tube

et al. 2016

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“…MRT involves the application of an array of spatially fractionated microbeams sourced from third generation synchrotrons, with beam widths ranging from 25 to 75 µm, and a pitch of 200-400 µm [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Microbeam peak doses of between 500-1000 Gy can be delivered safely due to the wellknown dose volume effect [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…The peak doses are typically 20-100 times higher than the valley [5,6,7]. Small PVDRs indicate that the valley dose between adjacent microbeams, is large in relation to the peak dose.…”

Section: Introductionmentioning

confidence: 99%

“…When made comparable to the large peak doses, this indicates better tumour coverage [7,8]. Conversely, a large PVDR and small valley dose may be more accommodating for tissue recovery, allowing normal tissue to be spared through the dose-volume effect [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Optimizing dose enhancement with Ta 2 O 5 nanoparticles for synchrotron microbeam activated radiation therapy

et al. 2016

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Microbeam Radiation Therapy (MRT) exploits tumour selectivity and normal tissue sparing with spatially fractionated kilovoltage X-ray microbeams through the dose volume effect. Experimental measurements with Ta 2 O 5 nanoparticles (NPs) in 9L gliosarcoma treated with MRT at the Australian Synchrotron, increased the treatment efficiency. Ta 2 O 5 NPs were observed to form shells around cell nuclei which may be the reason for their efficiency in MRT. In this article, our experimental observation of NP shell formation is the basis of a Geant4 radiation transport study to characterise dose enhancement by Ta 2 O 5 NPs in MRT. Our study showed that NP shells enhance the physical dose depending microbeam energy and their location relative to a single microbeam. For monochromatic microbeam energies below ∼70 keV, NP shells show highly localised dose enhancement due to the short range of associated secondary electrons. Low microbeam energies indicate better targeted treatment by allowing higher microbeam doses to be administered to tumours and better exploit the spatial fractionation related selectivity observed with MRT. For microbeam energies above ∼100 keV, NP shells extend the physical dose enhancement due to longer-range secondary electrons. Again, with NPs selectively internalised, the local effectiveness of MRT is expected to increase in the tumour. Dose enhancement produced by the shell aggregate varied more significantly in the cell population, depending on its location, when compared to a homogeneous NP distribution. These combined simulation and experimental data provide first evidence for optimising MRT through the incorporation of newly observed Ta 2 O 5 NP distributions within 9L cancer cells. Disciplines Engineering | Science and Technology Studies Publication DetailsEngels, E., Corde, S., McKinnon, S., Incerti, S., Konstantinov, K., Rozenfeld, A., Tehei, M., . Optimizing dose enhancement with Ta2O5 nanoparticles for synchrotron microbeam activated radiation therapy. Physica Medica: an international journal devoted to the applications of physics to medicine and biology, 32 (12)

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Neuropathology of ablation of rat gliosarcomas and contiguous brain tissues using a microplanar beam of synchrotron-wiggler-generated X rays

et al. 1998

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Adult‐rat‐brain tissues display an unusually high resistance to necrosis when serially irradiated with parallel, thin slices of a microplanar (i.e., microscopically thin and macroscopically broad) beam of synchrotron‐wiggler‐generated, approx. 35–120 keV (median approx. 50 keV) Gd‐filtered X rays at skin‐entrance absorbed doses of 312 to 5000 Gy per slice. Such microplanar beams were used to irradiate young adult rats bearing right frontocerebral 9L gliosarcomas (approx. 4 mm diameter), through a volume of tissue containing the tumor and contiguous brain tissue, either in a single array or in 2 orthogonally crossed arrays of tissue slices. Each array included 101 parallel microplanar slices, 100 μm center‐to‐center distance, each slice being approx. 25 μm wide and 12 mm high, with skin‐entrance absorbed doses of 312.5 Gy or 625 Gy per slice. Compared with unirradiated controls with a median survival time of 20 days after tumor initiation, the median survival time was extended in irradiated rats by 139 days (625 Gy, crossed arrays), 96 days (312.Gy, crossed arrays) or 24 days (625 Gy, single array). The tumors disappeared in 22 of the 36 irradiated rats, 4/ 11 even after unidirectional microbeam irradiation. The extent and severity of radiation damage to the normal brain in rats with or without tumor was graded histopathologically. Correlation of those grades with radiation doses shows that loss of tissue structure was confined to beam‐crossing regions and that only minor damage was done to zones of the brain irradiated unidirectionally. Int. J. Cancer 78:654–660, 1998. © 1998 Wiley‐Liss, Inc.

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Microbeam radiation therapy

Cited by 269 publications

References 0 publications

A preclinical microbeam facility with a conventional x‐ray tube

A preclinical microbeam facility with a conventional x‐ray tube

Optimizing dose enhancement with Ta 2 O 5 nanoparticles for synchrotron microbeam activated radiation therapy

Neuropathology of ablation of rat gliosarcomas and contiguous brain tissues using a microplanar beam of synchrotron-wiggler-generated X rays

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