arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.12163cs.CVphysics.med-ph
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利用约束结构和改进的目标检测网络从有限视野的CT图像中检测第12节脊椎骨用于图像引导放射治疗

Using constraint structure and an improved object detection network to detect the 12^{th} Vertebra from CT images with a limited field of view for image-guided radiotherapy

Massachusetts General Hospital(麻省总医院);CVCS

Yunhe Xie, Kongbin Kang, Gregory Sharp, David P. Gierga, Theodore S. Hong, Thomas Bortfeld

摘要:

图像引导已经广泛应用于放射治疗。从有限的视野中正确识别解剖标志的限界框是成功的关键。在图像引导放射治疗(IGRT)中,像第12节椎骨(T12)这样的标志的检测仍然需要繁琐的手动检查和注释;上下错位到错误的椎体仍然相对常见。有必要开发一种自动化的方法来从图像中检测这些地标。训练模型以自动识别T12椎骨的挑战主要是T12和相邻椎骨之间的高形状相似性、有限的注释数据和类别不平衡。本研究提出一种新的三维检测网络,只需要少量的训练数据。该方法具有以下创新点:1)引入辅助网络构建约束特征映射,提高模型的泛化能力,尤其是在约束结构比主结构更易检测的情况下; 2)改进检测头和目标函数,实现精确的限界框检测; 3)改进损失函数,解决高类别不平衡问题。我们提出的网络进行了训练,验证和测试的anotated CT图像从55名患者,并表现出准确区分T12椎骨与其相邻的椎骨的形状相似性高。我们提出的算法产生的限界框中心和大小的误差分别为3.98 \pm2.04mm和16.83 \pm8.34mm。在IoU阈值为0.35和0.5时,我们的方法在平均精度(AP)方面显著优于最先进的Retina-Net 3D,AP分别从0增加到95.4和0增加到64.7。总之,我们的方法有很大的潜力被整合到临床工作流程,以提高IGRT的安全性。

英文摘要:

Image guidance has been widely used in radiation therapy. Correctly identifying the bounding box of the anatomical landmarks from limited field of views is the key to success. In image-guided radiation therapy (IGRT), the detection of those landmarks like the 12th vertebra (T12) still requires tedious manual inspections and annotations; and superior-inferior misalignment to the wrong vertebral body is still relatively common. It is necessary to develop an automated approach to detect those landmarks from images. The challenges of training a model to identify T12 vertebrae automatically mainly are high shape similarity between T12 and neighboring vertebrae, limited annotated data, and class imbalance. This study proposed a novel 3D detection network, requiring only a small amount of training data. Our approach has the following innovations, including 1) the introduction of an auxiliary network to build constraint feature map for improving the model's generalization, especially when the constraint structure is easier to be detected than the main one; 2) an improved detection head and target functions for accurate bounding box detection; and 3) an improved loss functions to address the high class imbalance. Our proposed network was trained, validated and tested on anotated CT images from 55 patients and demonstrated accurate distinguish T12 vertebra from its neighboring vertebrae of high shape similarity. Our proposed algorithm yielded the bounding box center and size errors of 3.98\pm2.04mm and 16.83\pm8.34mm, respectively. Our approach significantly outperformed state-of-the-arts Retina-Net3D in average precision (AP) at IoU thresholds of 0.35 and 0.5, with AP increasing from 0 to 95.4 and 0 to 64.7, respectively. In summary, our approach has a great potential to be integrated into the clinical workflow to improve the safety of IGRT.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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