Development of a next generation X-ray CT with energy spectra of incident photons

开发具有入射光子能谱的下一代 X 射线 CT

• 批准号: 16390344
• 负责人: OGAWA Koichi
• 金额: $ 9.28万
• 依托单位: Hosei University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16390344/
• 关键词: x-ray CT; energy spectrum; semiconductor detector; photon counting; high spatial resolution; contrast resolution; beam hardening; Monte Carlo simulation; モンテカルロシミュレーション

In 2004 we have made a photon transporting code with Monte Carlo method for x-ray photon and evaluated the validity of our proposed photon counting method. The test was performed in terms of (1)improvement of the contrast resolution, (2)reduction of x-ray intensity, and (3)elimination of the beam hardening effect. The results of simulations showed that we could improve the low level contrast resolution about three times compared with the conventional CT method which used the energy fluence of x-rays. For the beam hardening effect we could eliminated the artifacts by weighing the measured energy spectra. And we applied this method to the energy spectra which could be obtained with the conventional modern X-ray system and good results. With this consideration we designed a new photon counting detector which was made of CdTe material and evaluated the performance of the detector with a micro focus x-ray tube.In 2005 we performed several experiment with the newly developed x-ray detector and the performance was compared with the results of Monte Carlo simulation data. For the tested materials we chosen water, Fe, Ca, alcohol and we measured transmitted x-rays with the photon counting method. In this experiment we set several thresholds for discriminating x-rays with their energy and the experiment value was compared with the ideal value. The experiment data showed that we could increase the low density contrast with energy weighted count data and also decrease the beam-hardening artifacts with energy weighted count data. Unfortunately the reconstructed CT images had some ring artifacts which were caused by the non-uniformity of sensitivity of the detector, but this problem could overcome with an appropriate interpolation method for the measured count data.

2004年，我们用蒙特卡罗方法实现了x射线光子的传输编码，并对所提出的光子计数方法的有效性进行了评价。测试从(1)提高对比度分辨率，(2)降低x射线强度，(3)消除光束硬化效应三个方面进行。仿真结果表明，与利用x射线能量影响的传统CT方法相比，该方法可将低水平对比度分辨率提高约3倍。对于光束硬化效应，我们可以通过测量能谱来消除伪影。并将该方法应用于传统的现代x射线系统所能得到的能谱，取得了较好的结果。为此，我们设计了一种新的CdTe材料光子计数探测器，并利用微聚焦x射线管对探测器的性能进行了评价。2005年，我们用新研制的x射线探测器进行了多次实验，并将其性能与蒙特卡罗模拟数据的结果进行了比较。对于测试材料，我们选择了水、铁、钙和酒精，并用光子计数法测量了透射的x射线。在这个实验中，我们设置了几个阈值来区分x射线的能量，并将实验值与理想值进行了比较。实验数据表明，利用能量加权计数数据可以提高低密度对比度，减少波束硬化伪影。由于检测器灵敏度的不均匀性，重建的CT图像存在环状伪影，但通过对实测计数数据进行适当的插值可以克服这一问题。

项目成果

Reduction of artifacts appeared on an X-ray CT image with a photon counting detector

使用光子计数探测器减少 X 射线 CT 图像上出现的伪影

• 发表时间: 2006
• 期刊: Japanese Journal of Medical Physics 26(Suppliment 2)
• 作者: 加藤和夫;和田森直;松田甚一;高橋英明;宇塚岳夫;田中隆一;小輪瀬一彦;小輪瀬一彦;K.Kowase
• 通讯作者: K.Kowase

Proposal on photon counting method for x-ray CT

X射线CT光子计数方法的提案

• 发表时间: 2004
• 期刊: Medical Imaging Technology 21(suppl, P1-03)
• 作者: 加藤和夫;和田森直;松田甚一;高橋英明;宇塚岳夫;田中隆一;小輪瀬一彦;小輪瀬一彦;K.Kowase;K.Kowase;小輪瀬一彦;小輪瀬一彦;吉竹純平;K.Kowase;小輪瀬一彦;K.Kowase;小輪瀬一彦;春多伸洋;渋沢 創;Koichi Ogawa;H.Shibusawa
• 通讯作者: H.Shibusawa

Photon counting X-ray CT with a CdTe semiconductor detector

使用 CdTe 半导体探测器进行光子计数 X 射线 CT

• 发表时间: 2005
• 期刊: Japanese Journal of Medical Physics 25・3-1
• 作者: 加藤和夫;和田森直;松田甚一;高橋英明;宇塚岳夫;田中隆一;小輪瀬一彦;小輪瀬一彦;K.Kowase;K.Kowase;小輪瀬一彦;小輪瀬一彦;吉竹純平;K.Kowase
• 通讯作者: K.Kowase

Simulation Study on a Photon Counting X-ray CT System

光子计数X射线CT系统仿真研究

• 发表时间: 2004
• 期刊: Proceedings of IEEE Nuclear Science Symposium and Medical Imaging Conference Vol.5
• 作者: 加藤和夫;和田森直;松田甚一;高橋英明;宇塚岳夫;田中隆一;小輪瀬一彦;小輪瀬一彦;K.Kowase;K.Kowase;小輪瀬一彦;小輪瀬一彦;吉竹純平;K.Kowase;小輪瀬一彦;K.Kowase;小輪瀬一彦;春多伸洋;渋沢 創;Koichi Ogawa
• 通讯作者: Koichi Ogawa

X-ray CT imaging with an energy-windowed photon counting line detector

使用能量窗光子计数线探测器进行 X 射线 CT 成像

• 发表时间: 2006
• 期刊: Japanese Journal of Medical Physics 26(Suppliment 2)
• 作者: 加藤和夫;和田森直;松田甚一;高橋英明;宇塚岳夫;田中隆一;小輪瀬一彦;小輪瀬一彦;K.Kowase;K.Kowase
• 通讯作者: K.Kowase