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首页> 外文期刊>Medical Physics >Development of high quantum efficiency flat panel detectors for portal imaging: intrinsic spatial resolution.
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Development of high quantum efficiency flat panel detectors for portal imaging: intrinsic spatial resolution.

机译：用于门禁成像的高量子效率平板探测器的开发：内在空间分辨率。

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摘要

Recently developed flat panel detectors have been proven to have a much better image quality than conventional electronic portal imaging devices (EPIDs). They are, however, not yet the ideal systems for portal imaging application due to the low x-ray absorption, i.e., low quantum efficiency (QE), which is typically on the order of 2-4% as compared to the theoretical limit of 100%. The QE of current flat panel systems can be improved by significantly increasing the thickness of the energy conversion layer (i.e., amorphous selenium or phosphor screen). This, however, will be at the expense of a decrease in spatial resolution mainly due to x-ray scatter in the conversion layer (and also the spread of optical photons in the case of phosphor screen). In this paper, we investigate theoretically the intrinsic spatial resolution of a high QE flat panel detector with a new energy conversion layer that is much denser and thicker than that of current flat panel systems. The modulation transfer function (MTF) of the system is calculated based on a theoretical model using a novel approach, which uses an analytical expression for absorbed dose. It is found that if appropriate materials are used for the conversion layer, then the intrinsic MTF of the high QE flat panel is better than that of current EPIDs, and in addition they have a high QE (e.g., approximately 60%). Some general rules for the design of the conversion layer to achieve both high QE and high resolution as well as high DQE are also discussed.
机译：事实证明，最近开发的平板探测器比传统的电子门禁成像设备（EPID）具有更好的图像质量。但是，由于它们的低X射线吸收（即低量子效率（QE），与理论上的理论极限相比通常为2-4％的数量），它们还不是用于门户成像的理想系统。 100％。可以通过显着增加能量转换层（即，非晶硒或磷屏）的厚度来改善当前平板系统的QE。然而，这将以空间分辨率的降低为代价，这主要归因于转换层中的x射线散射（以及在荧光屏的情况下，光子的扩散）。在本文中，我们从理论上研究具有新的能量转换层的高QE平板探测器的固有空间分辨率，该新的能量转换层比当前的平板系统更致密，更厚。系统的调制传递函数（MTF）是基于理论模型使用一种新颖的方法计算得出的，该方法使用了一个吸收剂量的解析表达式。已经发现，如果将适当的材料用于转换层，则高QE平板的固有MTF优于当前EPID的固有MTF，并且它们还具有高QE（例如，大约60％）。还讨论了用于实现高QE和高分辨率以及高DQE的转换层设计的一些一般规则。

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