Physics considerations in MV-CBCT multi-layer imager design.
Physics considerations in MV-CBCT multi-layer imager design.
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DOI：
10.1088/1361-6560/aac8c6
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发表时间：
2018-06-20
影响因子：
3.5
通讯作者：
Berbeco R
中科院分区：
文献类型：
--
作者：
Hu YH;Fueglistaller R;Myronakis M;Rottmann J;Wang A;Shedlock D;Morf D;Baturin P;Huber P;Star-Lack J;Berbeco R
使用电子射野成像（EPID）的兆伏（MV）锥形束计算机断层扫描（CBCT）提供了有利的功能，包括3D标测、治疗射束配准、高z伪影抑制和直接辐射剂量计算。由于图像质量限制和对成像剂量的担忧，采用速度放缓。已经探索了成像器设计的发展，包括像素化闪烁器、结构化磷光体、廉价闪烁材料和多层成像器（MLI）架构，以提高EPID图像质量并降低成像剂量。本研究采用混合蒙特卡罗和线性系统模型来确定探测器设计元素的影响，如多层结构和闪烁材料。我们遵循图像质量的度量，包括从投影图像到3D重建再到平面内切片的调制传递函数（MTF）和噪声功率谱（SNR），并应用基于任务的品质因数（理想观察者信噪比（d′））来确定探测器设计对目标可探测性的影响。一般来说，探测能力受到探测器噪声性能的限制。使用所有层的单一闪烁材料部署MLI成像仪可以改善噪声性能，并且d′与层数呈线性关系。通常，使用较厚的吸收器改善X射线吸收导致改善的DQE（0）。然而，如果光输出低，则性能将受到相对高剂量的电子噪声的影响，从而导致图像质量快速下降。最大化异质MLI探测器（即多种不同闪烁材料）中的图像质量最受限制总噪声的影响。然而，虽然是二阶效应，但最大化MLI检测器的总空间分辨率是每层的强度贡献与其单个MTF之间的平衡。因此，虽然较薄的闪烁体可以产生最大的单层MTF，但是与较厚的闪烁体相比，其量子效率将相对较低，并且因此，强度贡献可能不足以显著改善总检测器MTF。
Megavoltage (MV) cone-beam computed tomography (CBCT) using an electronic portal imaging (EPID) offers advantageous features, including 3D mapping, treatment beam registration, high-z artifact suppression, and direct radiation dose calculation. Adoption has been slowed by image quality limitations and concerns about imaging dose. Developments in imager design, including pixelated scintillators, structured phosphors, inexpensive scintillation materials, and multi-layer imager (MLI) architecture have been explored to improve EPID image quality and reduce imaging dose. The present study employs a hybrid Monte Carlo and linear systems model to determine the effect of detector design elements, such as multi-layer architecture and scintillation materials. We follow metrics of image quality including modulation transfer function (MTF) and noise power spectrum (NPS) from projection images to 3D reconstructions to in-plane slices and apply a task based figure-of-merit, the ideal observer signal-to-noise ratio (d′) to determine the effect of detector design on object detectability. Generally, detectability was limited by detector noise performance. Deploying an MLI imager with a single scintillation material for all layers yields improvement in noise performance and d′ linear with the number of layers. In general, improving x-ray absorption using thicker scintillators results in improved DQE(0). However, if light yield is low, performance will be affected by electronic noise at relatively high doses, resulting in rapid image quality degradation. Maximizing image quality in a heterogenous MLI detector (i.e. multiple different scintillation materials) is most affected by limiting total noise. However, while a second-order effect, maximizing total spatial resolution of the MLI detector is a balance between the intensity contribution of each layer against its individual MTF. So, while a thinner scintillator may yield a maximal individual-layer MTF, its quantum efficiency will be relatively low in comparison to a thicker scintillator and thus, intensity contribution may be insufficient to noticeably improve the total detector MTF.
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影响因子：
3.8
作者：
Hu YH;Myronakis M;Rottmann J;Wang A;Morf D;Shedlock D;Baturin P;Star-Lack J;Berbeco R
通讯作者：
Berbeco R
影响因子：
3.5
作者：
Rottmann J;Morf D;Fueglistaller R;Zentai G;Star-Lack J;Berbeco R
通讯作者：
Berbeco R
影响因子：
3.8
作者：
Fredenberg, Erik;Hemmendorff, Magnus;Danielsson, Mats
通讯作者：
Danielsson, Mats
影响因子：
3.8
作者：
Star-Lack, Josh;Shedlock, Daniel;Fahrig, Rebecca
通讯作者：
Fahrig, Rebecca
影响因子：
3.8
作者：
Star-Lack, Josh;Sun, Mingshan;Abel, Eric
通讯作者：
Abel, Eric