Amlan Dasgupta

Sensitometric response of Cd/sub 1-x/Zn/sub x/Te detectors for chest radiography

The sensitometric response of Cd/sub 1-x/Zn/sub x/Te semiconductor detectors using a geometrical chest phantom, within the X-ray diagnostic energy range, has been studied with the aim of optimizing the image quality parameters of these solid state-ionization devices. In addition, the dependence of the spatial resolution of a planar Cd/sub 1-x/Zn/sub x/Te substrate on the phantom thickness has been experimentally determined. The results of this study indicate that Cd/sub 1-x/Zn/sub x/Te detectors exhibit a high signal-to-noise ratio (S/N).

Study of detection efficiency of Cd/sub 1-x/Zn/sub x/Te detectors for digital radiography

In this paper, the signal-to-noise ratio (S/N) of resistive Cd/sub 1-x/Zn/sub x/Te semiconductor detectors, at different directions of irradiation, within the X-ray diagnostic energy range, has been experimentally studied. In addition, the dependence of the spatial resolution of a planar Cd/sub 1-x/Zn/sub x/Te substrate both on the applied bias voltage and thickness has been experimentally determined. The detection efficiency of semiconductor detectors depend upon the energy absorption efficiency as well as the collection efficiency. This study suggests that high signal-to-noise ratios can be obtained by optimally choosing which polarizing electrode is directly exposed to the incident X-ray beam, as well as on both the detector thickness and applied bias voltage. In addition, the experimental results on the temporal system MTF indicate a spatial resolution of >6 cy/mm. Besides the intrinsic charge transport characteristics of the semiconductor sample, by decreasing the collector size and optimizing the X-ray digital system geometry and temporal response, the temporal system MTF can be improved significantly. The research imaging detector system allows one to investigate methods to improve the detection and imaging performance parameters as part of the development of a digital radiographic system.

Feasibility study of a gas microstrip detector for medical applications

The goal of this study is to optimize the gas composition medium and strip geometry of a small-field of view gas- microstrip detector for medical imaging applications, such as x-ray digital imaging, computed tomography, quantitative autoradiography, including other nuclear medicine applications. The gas multiplication factor as well as the electrical parameters of the microstrip substrate have been studied. The results of this study indicate that an adequate gas multiplication process can be achieved with a Xe filled gas detector operating up to 10 atm.

Novel multimedia detectors for medical imaging

The objective of this research is to provide the physical and engineering principles of novel gas detector media operating on gas-microstrip principles. It is believed that the presented technology will have a significant impact on x-ray digital radiography, with emphasis on dual- energy imaging, computed tomography (CT), microtomography and x-ray microscopy, as well as in nuclear medicine, particularly in the important area of quantitative autoradiography, single photon emission tomography (SPECT) and (PET).

Sensitometric response of CdZnTe detectors for digital radiography

The sensitometric response of the CdZnTe semiconductor detectors, within the X-ray diagnostic energy range, have been studied with the aim of optimizing the image quality parameters of these solid state-ionization devices. The detected signal and noise contributions were measured and related to the tube setting current parameters. Furthermore, the detector contrast has been experimentally determined. The experimental results indicate that CdZnTe detectors have high resistivity, high signal-to-noise ratio, and high detector contrast resolution. Therefore, they appear to be potential candidates for imaging applications with applications in X-ray digital radiography, dual-energy radiography, and computed tomography (CT).

Electrical characterization of CdZnTe imaging detectors for digital radiography

The purpose of this study is to measure the electrical parameters of the Cd1-1ZnxTe detectors, with the aim of characterizing the optimal detector performance parameters for digital radiographic applications.

Evaluation of a CdZnTe dual-energy system

The purpose of the study is to optimize the input and the output parameters of a dual energy CdZnTe semiconductor detector for chest radiography. The optimal detector parameters were obtained by maximizing the figure of merit, defined as the ratio between the square of the signal-to- noise ratio and the absorbed dose, for chest radiography.

Contrast resolution study of CdZnTe detectors for medical imaging

The detected signal and noise contributions were measured and related to the radiation exposure and tube current tube setting. Furthermore, the detector contrast has been experimentally determined. The experimental results indicate that Cd1-xZnxTe detectors have high detector contrast resolution. Therefore, they appear to be very attractive for x-ray digital imaging applications.

Timing characteristics of a Cd/sub 1-x/Zn/sub x/Te detector-based X-ray imaging system

The timing characteristics of a planar Cd/sub 1-x/Zn/sub x/Te sample at each frequency of a scanning square-wave test pattern, has been measured. This study is aimed at evaluating the speed characteristics of a Cd/sub 1-x/Zn/sub x/Te detector for X-ray imaging and computed tomographic (CT) applications. The experimental results of this study indicate that the temporal response of a Cd/sub 1-x/Zn/sub x/Te detector based X-ray system, improves significantly by optimizing the X-ray tube and detector parameters.

Signal dispersion measurements on the gas detector volume of a dual-energy multimedia digital imaging sensor

In this study, experimental results on the signal dispersion of a gas detector volume of a multimedia imaging detector, operating on both gaseous and solid-state ionization principles, with specific emphasis on single X-ray exposure dual-energy radiography, are presented. The results of this study indicate that the gas detector volume of the multimedia detector technology exhibits excellent signal characteristics suitable for a large number of imaging applications. By focusing on the gas detector element, drift distance causes significant effects on both the amplitude and full-width at half maximum due to mobility dispersion and space-charge. An improved signal results with increasing gas pressure.