P. Ghotra

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).

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.

Enhanced X-Ray Detectors Using Polar Dopants for KCD Digital Radiography.

The goal of this study is to develop high resolution imaging detectors with applications in digital radiography and computed tomography. A physical treatment aimed at a better understanding of the line-spread function response of kinestatic charge detector (KCD) gas media, using dopants with permanent electric dipoles, is presented. Experimental results were obtained by operating a KCD krypton-filled detector at pressures up to 60 atm and constant electric field-to-gas density ratio doped with small amounts of polar or nonpolar polyatomic molecules with low or high ionization potential. The results clearly indicate that the addition of dopants having both low ionization potential and high dipole moment significantly enhance the imaging signal quality. An analysis of the experimental results aimed at providing a plausible interpretation of the reported observations is offered.

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.

Evaluation of a gas-microstrip dual-energy system

The use of a gas microstrip detector in dual-energy radiography for certain clinical applications is explored. Optimal conditions of this technology for digital chest radiography are presented. These optimal conditions were obtained via computer simulations. The gas microstrip detector shows promise for achieving high spatial resolution, high internal gain, low noise and through the use of dual-energy techniques, high contrast resolution.

Optimization of Cd 1–xZn xTe Detectors for Digital Radiography

In this study, measurements of the electrical and detection parameters of the Cd1-xZnxTe detectors, within the x-ray diagnostic energy range, have been performed with the aim of optimizing the image quality parameters of these solid-state-ionization detectors. Namely, the leakage current and system capacitance of the x-ray imaging system have been measured as they relate to signal parameters. Similarly, the detected signal and noise contributions were measured and related to the radiation exposure and tube current setting. Furthermore, the detector contrast has been experimentally determined. The experimental results indicate that Cd1-xZnxTe detectors have low leakage current, high resistivity, and high detector contrast resolution. Therefore, they appear to be very attractive for imaging applications with applications in x-ray digital radiography.

Progress in gas detector technology for medical imaging research

The x-ray capture, conversion into charge carriers, ion transport mechanisms and image formation mechanisms within a high-gas pressure digital radiographic system, operating up to 60 atm., are presented and analyzed. In detail, the physics of the high-pressure KCD imaging detectors is exposed, analyzed and related to the detector and image quality parameters. Specifically, this study indicates that ion diffusion cannot account for all the experimental observations. It advances the hypothesis that, at sufficiently high pressures, formation of molecular clusters with narrowed mobility distribution take place, through energy exchange mechanism, with local potential forces such that they compensate the space charge distortion of the applied field strength.

Real-time portal imaging devices operating on high-pressure gaseous electronic principles

A novel real-time portal imaging scanning detector, based on high-pressure gaseous electronics principles and operating up to 60 atmospheres, is presented and the predicted performance of this detector is analyzed. The idea is to utilize high pressure gaseous electronics imaging detectors operating in the saturation regime, aimed at improving image performance characteristics in real time portal imaging. As a result, beam localization errors are controlled, identified and corrected accurately and the patient radiotherapy treatment becomes more effective.

Ion-polar collisions in gas-filled KCD imaging detectors

A narrowing of the line spread function (LSF) has been observed when small amounts of low ionization potential polar dopant molecules were added to gas-filled high pressure kinestatic charge detector (KCD) for x-ray digital radiography. The LSF narrowing is attributed to different coexisting physical mechanisms. In this study, the impact of long-range dipole moment forces, associated with low ionization potential polar molecules, during ion-polars collisions, is investigated. Finally, this study is implemented with experimental examples.