Non-invasive cardiac-pulmonary gating is proposed to improve the imaging resolution. It produces signals based on the cardiac-pulmonary motion of an animal in real-time. The system with the non-invasive gating consist...Non-invasive cardiac-pulmonary gating is proposed to improve the imaging resolution. It produces signals based on the cardiac-pulmonary motion of an animal in real-time. The system with the non-invasive gating consists of a digital signal processor （DSP）, an electrocardiography （ECG） detection circuit and a thermoeouple circuit. An enhanced R wave detection algorithm based on zero crossing counts is used to adjust the low sample frequency associated with the respiratory rate of an animal. The thermocouple recognizes the respiration phase by sensing the temperature changes of the nasal airflow of an animal. The proposed gating can accurately generate the gating signal for freely breathing mice （weight of around 0.03 kg）, and its respiratory signal is too weak to be detected. Apart from non-invasiveness, compared with other existing gating techniques, it occupies minimal space at lower cost. Actually, it can be used in micro-computed tomography （CT） and other systems needed to detect the cardiac-pulmonary motion. Several tests validate that the proposed cardiac-pulmonary gating can generate the gating signal as required. By using the gating technique, the image resolution is improved.展开更多
CBCT scanners have been widely used in angiography,radiotherapy guidance,mammography and oral maxillofacial imaging.To cut detector size,reduce manufacturing costs and radiation dose while keeping a reasonable FOV,the...CBCT scanners have been widely used in angiography,radiotherapy guidance,mammography and oral maxillofacial imaging.To cut detector size,reduce manufacturing costs and radiation dose while keeping a reasonable FOV,the flat panel detector can be placed off-center horizontally.This scanning configuration extends the FOV effectively.However,each projection is transversely truncated,bringing errors and artifacts in reconstruction.In this paper,a simple but practical method is proposed for this scanning geometry based on truncation compensation and the modified FDK algorithm.Numerical simulations with jaw phantom were conducted to evaluate the accuracy and practicability of the proposed method.A novel CBCT system for maxillofacial imaging is used for clinical test,which is equipped with an off-center small size flat panel detector.Results show that reconstruction accuracy is acceptable for clinical use,and the image quality appears sufficient for specific diagnostic requirements.It provides a novel solution for clinical CBCT system,in order to reduce radiation dose and manufacturing cost.展开更多
In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In t...In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In this paper, a novel design of industrial computed tomography(ICT) system with a linac as X-ray source is proposed to complete the task. The major advantage of the proposed system is that it can provide visualized images of internal structures of the running aero-engine without physical disturbance, which makes it possible to extract the accurate geometry information. The main idea behind this design is to measure the projection data from various views for reconstructions making use of the rotations of the aero-engine blades, instead of the mechanical rotations in the conventional ICT system. However, due to high speed rotation of the aero-engine blades,the system faces more challenges than conventional ICT systems both in data acquisitions and reconstruction algorithms. The challenges and corresponding solutions are presented in this paper. In conclusion, the proposed ICT system provides a powerful tool for monitoring the running aero-engines.展开更多
In this paper, a measurement method for cross-sectional temperature distribution is addressed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature distributions are estimated us...In this paper, a measurement method for cross-sectional temperature distribution is addressed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature distributions are estimated using the time of flight data of several ultrasonic propagation paths. The times of the flight data contain both temperature and wind effect, and the method to select only temperature component is introduced. A filtered back projection method is applied to reconstruct the temperature distributions from the time of flight data. An experimental system was designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.展开更多
The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in ...The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in terms of uniformity, spatial linearity and spatial resolution and micro-CT unit in terms of uniformity, spatial linearity, spatial resolution, diffusion rate, low contrast detectability, Hounsfield unit linearity and slice thickness. The construction material is Plexiglas. As for the implementation, it was made on a micro-SPECT/CT machine of the type “speCZT eXplore CT 120”. Compared to the NEMA NU 4-2008 image quality phantom, this phantom offers micro-CT quality control and is more efficient in control of spatial resolution for micro-SPECT and micro- PET systems.展开更多
This is a GATE-simulation study of the Siemens Biograph DUO PET/CT system. It reports effects of changes in the thickness of the employed Lutetium Oxyorthosilicate(LSO) detectors. The PET/CT, a human body phantom and ...This is a GATE-simulation study of the Siemens Biograph DUO PET/CT system. It reports effects of changes in the thickness of the employed Lutetium Oxyorthosilicate(LSO) detectors. The PET/CT, a human body phantom and a cylindrical F-18 FDG source were simulated. Validation measurements were conducted. The results indicate that LSO thickness increase degrades spatial resolution, improves relative energy resolution from 9.0% to 11.3% and increases signal-to-noise-ratio from 0.81 to 1.17. Thicker LSO crystals present greater axial sensitivity so as the detection efficiency of PET would be significantly enhanced.展开更多
基金Supported by the National Basic Research Program of China ("973" Program) (2006CB705700)~~
文摘Non-invasive cardiac-pulmonary gating is proposed to improve the imaging resolution. It produces signals based on the cardiac-pulmonary motion of an animal in real-time. The system with the non-invasive gating consists of a digital signal processor （DSP）, an electrocardiography （ECG） detection circuit and a thermoeouple circuit. An enhanced R wave detection algorithm based on zero crossing counts is used to adjust the low sample frequency associated with the respiratory rate of an animal. The thermocouple recognizes the respiration phase by sensing the temperature changes of the nasal airflow of an animal. The proposed gating can accurately generate the gating signal for freely breathing mice （weight of around 0.03 kg）, and its respiratory signal is too weak to be detected. Apart from non-invasiveness, compared with other existing gating techniques, it occupies minimal space at lower cost. Actually, it can be used in micro-computed tomography （CT） and other systems needed to detect the cardiac-pulmonary motion. Several tests validate that the proposed cardiac-pulmonary gating can generate the gating signal as required. By using the gating technique, the image resolution is improved.
基金Supported by National Key Technology R&D Program of the Ministry of Science and Technology(No.2012BAI07B05)
文摘CBCT scanners have been widely used in angiography,radiotherapy guidance,mammography and oral maxillofacial imaging.To cut detector size,reduce manufacturing costs and radiation dose while keeping a reasonable FOV,the flat panel detector can be placed off-center horizontally.This scanning configuration extends the FOV effectively.However,each projection is transversely truncated,bringing errors and artifacts in reconstruction.In this paper,a simple but practical method is proposed for this scanning geometry based on truncation compensation and the modified FDK algorithm.Numerical simulations with jaw phantom were conducted to evaluate the accuracy and practicability of the proposed method.A novel CBCT system for maxillofacial imaging is used for clinical test,which is equipped with an off-center small size flat panel detector.Results show that reconstruction accuracy is acceptable for clinical use,and the image quality appears sufficient for specific diagnostic requirements.It provides a novel solution for clinical CBCT system,in order to reduce radiation dose and manufacturing cost.
基金Supported by the Transportation Construction Science and Technology Project(No.201332849A090)
文摘In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In this paper, a novel design of industrial computed tomography(ICT) system with a linac as X-ray source is proposed to complete the task. The major advantage of the proposed system is that it can provide visualized images of internal structures of the running aero-engine without physical disturbance, which makes it possible to extract the accurate geometry information. The main idea behind this design is to measure the projection data from various views for reconstructions making use of the rotations of the aero-engine blades, instead of the mechanical rotations in the conventional ICT system. However, due to high speed rotation of the aero-engine blades,the system faces more challenges than conventional ICT systems both in data acquisitions and reconstruction algorithms. The challenges and corresponding solutions are presented in this paper. In conclusion, the proposed ICT system provides a powerful tool for monitoring the running aero-engines.
文摘In this paper, a measurement method for cross-sectional temperature distribution is addressed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature distributions are estimated using the time of flight data of several ultrasonic propagation paths. The times of the flight data contain both temperature and wind effect, and the method to select only temperature component is introduced. A filtered back projection method is applied to reconstruct the temperature distributions from the time of flight data. An experimental system was designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.
文摘The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in terms of uniformity, spatial linearity and spatial resolution and micro-CT unit in terms of uniformity, spatial linearity, spatial resolution, diffusion rate, low contrast detectability, Hounsfield unit linearity and slice thickness. The construction material is Plexiglas. As for the implementation, it was made on a micro-SPECT/CT machine of the type “speCZT eXplore CT 120”. Compared to the NEMA NU 4-2008 image quality phantom, this phantom offers micro-CT quality control and is more efficient in control of spatial resolution for micro-SPECT and micro- PET systems.
文摘This is a GATE-simulation study of the Siemens Biograph DUO PET/CT system. It reports effects of changes in the thickness of the employed Lutetium Oxyorthosilicate(LSO) detectors. The PET/CT, a human body phantom and a cylindrical F-18 FDG source were simulated. Validation measurements were conducted. The results indicate that LSO thickness increase degrades spatial resolution, improves relative energy resolution from 9.0% to 11.3% and increases signal-to-noise-ratio from 0.81 to 1.17. Thicker LSO crystals present greater axial sensitivity so as the detection efficiency of PET would be significantly enhanced.
