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首页> 外文期刊>Physics in medicine and biology. >Removal and effects of scatter-glare in cone-beam CT with an amorphous-silicon flat-panel detector.
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Removal and effects of scatter-glare in cone-beam CT with an amorphous-silicon flat-panel detector.

机译：使用非晶硅平板探测器消除锥束CT中的散射眩光及其影响。

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摘要

Scatter in a detector and its housing can result in image degradation. Typically, such scatter leads to a low-spatial frequency 'glare' superimposed on the primary signal. We infer the glare-spread function (GSF) of an amorphous-silicon flat-panel detector via an edge-spread technique. We demonstrate that this spread (referred to as 'scatter-glare' herein) causes a low-spatial frequency drop in the associated modulation-transfer function. This results in a compression of the range of reconstructed CT (computed tomography) numbers and is an impediment to accurate CT-number calibration. We show that it can also lead to visual artefacts. This explains previously unresolved CT-number discrepancies in an earlier work (Poludniowski et al 2009 Phys. Med. Biol. 54 3847). We demonstrate that after deconvolving the GSF from the projection images, in conjunction with a correction for phantom-scatter, the CT-number discrepancies disappear. We show results for an in-house-built phantom with inserts of tissue-equivalent materials and for a patient scan. We conclude that where scatter-glare has not been accounted for, the calibration of cone-beam CT numbers to material density will be compromised. The scatter-glare measurement method we propose is simple and requires no special equipment. The deconvolution process is also straightforward and relatively quick (60 ms per projection on a desktop PC).
机译：检测器及其外壳中的散射会导致图像质量下降。通常，这种散射会导致在主信号上叠加低空间频率的“眩光”。我们通过边缘扩散技术推断出非晶硅平板探测器的眩光扩散函数（GSF）。我们证明了这种扩散（在本文中称为“散射眩光”）导致相关调制传递函数中的低空间频率下降。这导致重建的CT（计算机断层扫描）数量范围的压缩，并且妨碍了精确的CT数量校准。我们证明它也可以导致视觉伪像。这解释了以前的工作中以前无法解决的CT编号差异（Poludniowski等，2009 Phys。Med。Biol。54 3847）。我们证明，将GSF从投影图像中解卷积后，再结合对幻像散布的校正，CT编号差异将消失。我们显示了带有等效组织插入物的内部幻像以及患者扫描结果。我们得出的结论是，在没有考虑散射眩光的情况下，锥束CT数对材料密度的校准将受到影响。我们提出的散射眩光测量方法很简单，不需要特殊设备。反卷积过程也很简单且相对较快（台式PC上每个投影60毫秒）。

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