Dose distribution of a 125 keV mean energy microplanar x-ray beam for basic studies on microbeam radiotherapy

Ohno, Yumiko; Torikoshi, M.; Suzuki, Masao; Umetani, Keiji; Imai, Yasuhiko; Uesugi, Kentaro; Yagi, Naoto

doi:10.1118/1.2940157

Cited by 21 publications

(24 citation statements)

References 18 publications

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“…The nominal beam width was 25 mm (industrial-grade kapton sheets). Ohno et al [23] reported the effective beam width for this collimator at full width half maximum was 21.2-23.1 mm with a centre-to-centre spacing of exactly 200 mm. The peakto-valley dose ratio for this collimator was measured using radiochromic films of different sensitivity.…”

Section: Synchrotron Radiation Source and Microbeam Generationmentioning

confidence: 99%

“…The synchrotron X-ray beam was filtered by passing through a 3 mm-thick copper absorber that preferentially absorbs low energy X-rays and hence increases the beam's mean energy. The mean energy of the filtered X-ray beam was 125 keV [23]. A tungsten/ kapton collimator segmented the BB into a lattice of planar microbeams.…”

Section: Synchrotron Radiation Source and Microbeam Generationmentioning

confidence: 99%

“…In a solid water phantom, the dose in the valley region is typically between 1% and 2% of the dose in the peaks. A complete description of the dosimetry used for this MRT research is described elsewhere [10,23].…”

Section: Synchrotron Radiation Source and Microbeam Generationmentioning

confidence: 99%

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Biodosimetric quantification of short-term synchrotron microbeam versus broad-beam radiation damage to mouse skin using a dermatopathological scoring system

Priyadarshika

Crosbie²,

Kumar³

et al. 2011

BJR

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Objectives: Microbeam radiotherapy (MRT) with wafers of microscopically narrow, synchrotron generated X-rays is being used for pre-clinical cancer trials in animal models. It has been shown that high dose MRT can be effective at destroying tumours in animal models, while causing unexpectedly little damage to normal tissue. The aim of this study was to use a dermatopathological scoring system to quantify and compare the acute biological response of normal mouse skin with microplanar and broad-beam (BB) radiation as a basis for biological dosimetry. Method: The skin flaps of three groups of mice were irradiated with high entrance doses (200 Gy, 400 Gy and 800 Gy) of MRT and BB and low dose BB (11 Gy, 22 Gy and 44 Gy). The mice were culled at different time-points post-irradiation. Skin sections were evaluated histologically using the following parameters: epidermal cell death, nuclear enlargement, spongiosis, hair follicle damage and dermal inflammation. The fields of irradiation were identified by cH2AX-positive immunostaining. Results: The acute radiation damage in skin from high dose MRT was significantly lower than from high dose BB and, importantly, similar to low dose BB. Conclusion: The integrated MRT dose was more relevant than the peak or valley dose when comparing with BB fields. In MRT-treated skin, the apoptotic cells of epidermis and hair follicles were not confined to the microbeam paths.

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Section: Synchrotron Radiation Source and Microbeam Generationmentioning

confidence: 99%

Section: Synchrotron Radiation Source and Microbeam Generationmentioning

confidence: 99%

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Biodosimetric quantification of short-term synchrotron microbeam versus broad-beam radiation damage to mouse skin using a dermatopathological scoring system

Priyadarshika

Crosbie²,

Kumar³

et al. 2011

BJR

View full text Add to dashboard Cite

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“…Each microbeam is approximately 25-μm wide with a spacing of 200 μm between adjacent microbeams. The details of the beams and multislit irradiation system have been described by Kashino et al [9], Ohno et al [16] and Nariyama et al [17]. The cells were then fixed with 4% paraformaldehyde in phosphate buffer saline immediately after irradiation and at 6, 12 and 24 h after irradiation.…”

Section: Cell Irradiation With Microplanar Beam At Spring-8mentioning

confidence: 99%

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

et al. 2011

Self Cite

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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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“…14,15 The ultra-high dose rates (>100 Gy/s) allow for the instantaneous delivery of the high dose in tens of milliseconds, thus maintaining the microbeam profile despite the physiological motion which is on the order of hundreds of micrometers and the time scale of 100 s of milliseconds. Another reason that so far the method could not be implemented with sources other than synchrotron is that the near parallel beam and high dose rate make it easier to collimate the beam into parallel microplanar beams.…”

Section: A Microbeam Radiation Therapy (Mrt)mentioning

confidence: 99%

Physiologically gated microbeam radiation using a field emission x‐ray source array

et al. 2014

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Purpose: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring. Methods: The CNT field emission x-ray source array with a narrow line focal track was operated at 160 kVp. The x-ray radiation was collimated to a single 280 μm wide microbeam at entrance. The microbeam beam pattern was recorded using EBT2 Gafchromic c films. For the feasibility study, a strip of EBT2 film was attached to an oscillating mechanical phantom mimicking mouse chest respiratory motion. The servo arm was put against a pressure sensor to monitor the motion. The film was irradiated with three microbeams under gated and nongated conditions and the full width at half maximums and PVDRs were compared. An in vivo study was also performed with adult male athymic mice. The liver was chosen as the target organ for proof of concept due to its large motion during respiration compared to other organs. The mouse was immobilized in a specialized mouse bed and anesthetized using isoflurane. A pressure sensor was attached to a mouse's chest to monitor its respiration. The output signal triggered the electron extraction voltage of the field emission source such that x-ray was generated only during a portion of the mouse respiratory cycle when there was minimum motion. Parallel planes of microbeams with 12.4 Gy/plane dose and 900 μm pitch were delivered. The microbeam profiles with and without gating were analyzed using γ -H2Ax immunofluorescence staining. Results: The phantom study showed that the respiratory motion caused a 50% drop in PVDR from 11.5 when there is no motion to 5.4, whereas there was only a 5.5% decrease in PVDR for gated irradiation compared to the no motion case. In the in vivo study, the histology result showed gating increased PVDR by a factor of 2.4 compared to the nongated case, similar to the result from the phantom study. The full width at tenth maximum of the microbeam decreased by 40% in gating in vivo and close to 38% with phantom studies. Conclusions:The CNT field emission x-ray source array can be synchronized to physiological signals for gated delivery of x-ray radiation to minimize motion-induced beam blurring. Gated MRT reduces valley dose between lines during long-time radiation of a moving object. The technique allows for...

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Dose distribution of a 125 keV mean energy microplanar x-ray beam for basic studies on microbeam radiotherapy

Cited by 21 publications

References 18 publications

Biodosimetric quantification of short-term synchrotron microbeam versus broad-beam radiation damage to mouse skin using a dermatopathological scoring system

Biodosimetric quantification of short-term synchrotron microbeam versus broad-beam radiation damage to mouse skin using a dermatopathological scoring system

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

Physiologically gated microbeam radiation using a field emission x‐ray source array

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