WordNet

the top or extreme point of something (usually a mountain or hill); "the view from the peak was magnificent"; "they clambered to the tip of Monadnock"; "the region is a few molecules wide at the summit" (同)crown, crest, top, tip, summit
a leguminous plant of the genus Pisum with small white flowers and long green pods containing edible green seeds (同)pea plant
the fruit or seed of a pea plant
seed of a pea plant used for food
having or rising to a peak; "the peaked ceiling"; "the islands peaked hills"
Confederate general during the American Civil War who was defeated by Grant in the battle of Chattanooga (1817-1876) (同)Braxton Bragg
the 17th letter of the Hebrew alphabet

PrepTutorEJDIC

(とがった)『山頂』,峰;最も高い所 / (独立した)鋭峰,孤峰 / 『とがった先』,先端 / (事の)最頂点,絶頂,ピーク / (帽子の)前びさし / 最高の,最大の,ピークの / 頂点に達する,最高(最大)になる
《古》〈勢いが〉衰える;〈人が〉病み衰える,やつれる
『エンドウ』;エンドウ豆
先のとがった;前びさしのある
やせた,やつれた

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/25 21:15:34」(JST)

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The Bragg curve of 5.49 MeV alphas in air has its peak to the right and is skewed to the left, unlike the x-ray beam below.

The dose produced by a native and by a modified proton beam in passing through tissue, compared to the absorption of a photon or x-ray beam

The Bragg peak is a pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. For protons, α-rays, and other ion rays, the peak occurs immediately before the particles come to rest. This is called Bragg peak, for William Henry Bragg who discovered it in 1903.

When a fast charged particle moves through matter, it ionizes atoms of the material and deposits a dose along its path. A peak occurs because the interaction cross section increases as the charged particle's energy decreases. In the upper figure, it is the peak for alpha particles of 5.49 MeV moving through air. In the lower figure, it is the narrow peak of the "native" proton beam curve which is produced by a particle accelerator of 250 MeV. The figure also shows the absorption of a beam of energetic photons (X rays) which is entirely different in nature; the curve is mainly exponential.

The phenomenon is exploited in particle therapy of cancer, to concentrate the effect of light ion beams on the tumor being treated while minimizing the effect on the surrounding healthy tissue.^[1] The blue curve in the figure ("modified proton beam") shows how the originally monoenergetic proton beam with the sharp peak is widened by increasing the range of energies, so that a larger tumor volume can be treated. This can be achieved by using variable thickness attenuators like spinning wedges.

References

^ Trikalinos, TA; et al. (2009). Particle Beam Radiation Therapies for Cancer [Internet]. Comparative Effectiveness Technical Briefs, No. 1. Rockville (MD): Agency for Healthcare Research and Quality (US). pp. ES1–ES5.

External links

Douglas J. Wagenaar, Ph.D, 7.1.3 The Bragg Curve // RADIATION PHYSICS PRINCIPLES, 1995

UpToDate Contents

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4. がん治療における放射線治療手技 radiation therapy techniques in cancer treatment
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English Journal

Molecular imprinted photonic crystal hydrogels for the rapid and label-free detection of imidacloprid.

Wang X, Mu Z, Liu R, Pu Y, Yin L.SourceKey Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, PR China.
Food chemistry.Food Chem.2013 Dec 15;141(4):3947-53. doi: 10.1016/j.foodchem.2013.06.024. Epub 2013 Jun 15.
A novel sensor for the rapid and label-free detection of imidacloprid was developed based on the combination of a colloidal crystal templating method and a molecular imprinting technique. The molecular imprinted photonic hydrogel film was prepared with methacrylic acid as monomers, ethylene glycol d
PMID 23993570

Induction and Persistence of Large γH2AX Foci by High Linear Energy Transfer Radiation in DNA-Dependent protein kinase-Deficient Cells.

Bracalente C, Ibañez IL, Molinari B, Palmieri M, Kreiner A, Valda A, Davidson J, Durán H.SourceDepartamento de Micro y Nanotecnología, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
International journal of radiation oncology, biology, physics.Int J Radiat Oncol Biol Phys.2013 Nov 15;87(4):785-94. doi: 10.1016/j.ijrobp.2013.07.014. Epub 2013 Aug 22.
PURPOSE: To evaluate the cell response to DNA double-strand breaks induced by low and high linear energy transfer (LET) radiations when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of the nonhomologous end-joining repair pathway, lacks kinase activity.METHOD
PMID 23972723

Japanese Journal

InGaN light-emitting diodes with embedded nanoporous GaN distributed Bragg reflectors

Shieh Bing-Cheng,Jhang Yuan-Chang,Huang Kun-Pin,Huang Wan-Chun,Dai Jing-Jie,Lai Chun-Feng,Lin Chia-Feng
Appl. Phys. Express 8(8), 082101, 2015-07-08
… InGaN-based light-emitting diodes (LEDs) with embedded conductive nanoporous GaN/undoped GaN (NP-GaN/u-GaN) distributed Bragg reflectors (DBRs) were demonstrated. … The measured center wavelength, peak reflectivity, and bandwidth of the nanoporous GaN DBR structure were 417 nm, 96.7%, and 34 nm, respectively. …
NAID 150000111055

Narrow-bandwidth and stable-wavelength operation of spatial beam-combining high-power laser-diode stack configuration using a single volume Bragg grating

Zheng Yujin,Kawashima Toshiyuki,Satoh Nakahiro,Sekine Takashi,Kan Hirofumi
Appl. Phys. Express 8(5), 052701, 2015-04-14
… The spectral bandwidth was effectively suppressed and the wavelength was locked for two high-power laser-diode (LD) stacks with an external-cavity configuration that consisted of a stripe mirror and volume Bragg grating. … During operation at a drive current of 100 A, the bandwidth was reduced from 2.59 to 0.31 nm (8.4-fold reduction), and a peak power output of 581 W was achieved. …
NAID 150000110561