High-sensitive X-ray fluoroscopy using chalcogenide glasses: Degradation of X-ray images
High-sensitive X-ray fluoroscopy using chalcogenide glasses: Degradation of X-ray images
批准号:
17560279
负责人:
SHIMAKAWA Koichi
金额:
$2.3万
依托单位:
依托单位国家:
日本
项目类别:
Grant-in-Aid for Scientific Research (C)
财政年份:
2005
资助国家:
日本
项目状态:
已结题
起止时间:
2005 至 2006
中文摘要
无定形硒(a-Se)是一种可用于最近开发的用于医学成像的直接转换平板x射线图像探测器的x射线光导体。为了更好地理解a- se中的捕获和复合效应,我们研究了a- se薄膜中的光和x射线诱导光电流。x射线照射后的剩余光电流在夹层细胞中减少,而在共面细胞中增加。这些影响需要几个小时的时间才能恢复。结果表明,可以用VAP(价交替对)型带电缺陷来解释。由于累积的x射线照射,基于a- se的x射线探测器的灵敏度(疲劳)有所下降。灵敏度降低是砷硒探测器的缺点之一,会导致图像的重影。术语“重影”是指以前x射线曝光后的残留图像。在对鬼影的某些解释中,有人提出x射线暴露会导致产生更多新的深圈闭。为了获得稳定(和安全)的实时x射线图像(透视),必须克服以下问题:(1)x射线曝光导致x射线图像退化(2)响应时间延迟,大约几十秒,以获得正确的图像。在a-Se中观察到x射线对光电流的诱导效应。x射线照射后,共面光电流增大,夹层光电流减小。我们已经证明了共面电池和夹层电池在x射线对光电流的诱导效应方面具有完全不同的特性。在共面结构中,x射线产生的空穴的捕获改变了准费米能级,增加了光电流。在夹层结构中,当x射线诱导的电子被困在那里时,来自光载流子的捕获空穴充当复合中心。已经证明,x射线诱导电荷的捕获主导了图像中的“重影”。认为现有的x射线曝光条件不会产生新的缺陷。少
英文摘要
Amorphous selenium (a-Se) is one of the x-ray photoconductors that is available for use in recently developed direct conversion flat panel x-ray image detectors for medical imaging. To obtain a better understanding of trapping and recombination effects in a-Se, we have studied light and x-ray induced photocurrents in a-Se films. The residual photocurrent, after x-ray exposure, decreases in sandwich cells whereas it increases in coplanar cells. These effects are recovered over a time scale of hours. We show that the results can be interpreted by using VAP (valence alternation pair) type charged defects.a-Se based x-ray detectors have shown some decrease in the sensitivity (fatigue) as a result of accumulated x-ray exposure. Reduction of sensitivity is one of drawbacks of a-Se detectors, resulting in a ghosting images. The term ghosting means the residual image from previous x-ray exposure. In some explanation of ghosting it has been suggested that x-ray exposure should lead to the gener … More ation of new deep traps.To get stabilized (and safe) real-time X-ray image (fluoroscopy), the following problems should be overcome :(1) Degradation of X-ray images with exposing X-ray(2) Delay of the response time, around several ten seconds, for getting a proper image.X-ray induced effects on the photocurrent were observed in a-Se. After x-ray exposure, the photocurrent increases in coplanar and decreases in sandwich cells. We have shown that coplanar and sandwich cells have totally different characteristics in terms of x-ray induced effects on the photocurrent. In the coplanar structure, the trapping of x-ray generated holes modifies the quasi-Fermi level and increased the photocurrent. In the sandwich structure, the trapped holes from the photocarriers act as recombination centers, when the x-ray induced electrons are trapped there. It has been turned out that the trapping of X-ray induced charges dominate "ghosting" in the images. It is suggested that new defects are not created by the present x-ray exposure conditions. Less
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Photo-carrier transport in disordered organic TPD films
无序有机 TPD 薄膜中的光载流子传输
DOI:
--
发表时间:
2006
期刊:
J. Non-cryst. Solids 352
影响因子:
--
作者:
[K.Shimakawa, K.Murata, S.Matsumoto, H.Naito]
通讯作者:
H.Naito
Photo-carrier transport in disordered TPD films
无序 TPD 薄膜中的光载流子传输
DOI:
--
发表时间:
2006
期刊:
J.Non-cryst.Solids 352
影响因子:
--
作者:
[K.Shimakawa, K.Murata, S.Matsumoto, H.Naito]
通讯作者:
H.Naito
Recombination kinetics of very-long-lived photoluminescence decay in a-Si : H correlated with light-induced spin densities
a-Si : H 中超长寿命光致发光衰变的复合动力学与光诱导自旋密度相关
DOI:
--
发表时间:
2006
期刊:
Philos. Mag. Lett. 86
影响因子:
--
作者:
[T.Aoki, K.Ikeda, S.Kobayashi, K.Shimakawa]
通讯作者:
K.Shimakawa
DOI:
10.1103/physrevlett.95.206803
发表时间:
2005-11
期刊:
Physical review letters
影响因子:
8.6
作者:
[J. Hegedüs;K. Kohary;D. Pettifor;K. Shimakawa;S. Kugler]
通讯作者:
J. Hegedüs;K. Kohary;D. Pettifor;K. Shimakawa;S. Kugler
X-ray induced effects on photocurrents in amorphous Se films
X 射线对非晶 Se 薄膜光电流的影响
DOI:
--
发表时间:
2007
期刊:
Jpn. J. Appl. Phys 46
影响因子:
--
作者:
[K.Shimakawa, K.Fukami, H.Kishi, G.Belev, S.Kasap]
通讯作者:
S.Kasap
共 8 条
Control of X-ray induced defects in chalcogenide glasses : Large area X-ray sensor for medical use
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批准号:14550297
-
项目类别:Grant-in-Aid for Scientific Research (C)
-
资助金额:$2.56万
-
财政年份:2002
-
负责人:SHIMAKAWA Koichi
-
依托单位:
A new defect spectrosoopy using optical and electric noises : Application to a-Si : H
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批准号:12650307
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项目类别:Grant-in-Aid for Scientific Research (C)
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资助金额:$2.37万
-
财政年份:2000
-
负责人:SHIMAKAWA Koichi
-
依托单位:
Electrical and optical properties in rare earth-doped amorphous chalcogenides
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批准号:09650352
-
项目类别:Grant-in-Aid for Scientific Research (C)
-
资助金额:$2.18万
-
财政年份:1997
-
负责人:SHIMAKAWA Koichi
-
依托单位:
海外基金