Biomedical subjects

M M Tesic

Publications and source records attributed to M M Tesic.

6 recordsLinked to original sources

PubMed1985

Digital chest radiography: performance evaluation of a prototype unit.

Measurements of the physical performance of a prototype digital chest unit (DCU) are presented. The parameters evaluated were entrance skin exposure, system exposure response and dynamic range, system modulation transfer function (MTF), image noise levels, detective quantum efficiency (DQE) of the detector, and scatter suppression efficiency. Compared with conventional chest imaging systems, the unit has markedly greater exposure latitude, limited spatial resolution, a lower detector DQE, and virtually scatter-free images. Routine clinical exposure levels are comparable with the 1982 national average.

Equipment Design↗

PubMed1985

Detector for dual-energy digital radiography.

A detection scheme is described that allows one to accomplish dual-energy scanned projection digital radiography without switching the x-ray tube voltage. The method employs a high/low atomic number detector sandwich that simultaneously separates the x-ray beam transmitted by the patient into low and high energy components. To test the method, the response of a scanning linear array of energy-sensitive detectors was simulated, and bone and soft tissue images of an anthropomorphic chest phantom were obtained at 140 kVp. These were compared with similar images obtained by switching the x-ray tube voltage from 80 kVp to a heavily filtered 140 kVp. For comparable entrance skin exposures, the dual-energy detector images required a lower tube load and resulted in higher noise levels. The latter is attributable to the fact that the separation in energy between the high and low energy components is smaller with the dual-energy detector than with the voltage switching technique, and to misregistration problems associated with the simulation methodology. A detector design is also discussed that would result in improved energy separation and lower noise levels. In view of this possibility and the tube loading advantage, the method looks promising for digital scanned projection radiography.

Humans↗

PubMed1984

Single-slit digital radiography: some practical considerations.

Clinical evaluation of an experimental digital chest unit using a solid-state linear detector array has provided information regarding the postpatient photon flux required for clinically acceptable images. Results from computer simulation show that energy subtraction imaging of the chest by the method of x-ray-tube voltage switching will be unsuccessful unless it can be demonstrated clinically that a much lower number of photons per pixel is acceptable in energy subtracted images. In addition, x-ray-tube loading limitations preclude imaging of the abdominal and pelvic regions with this technology.

Analog-Digital Conversion↗

PubMed1983

Digital radiography of the chest: design features and considerations for a prototype unit.

The general features of a prototype digital chest unit are described along with the rationale for the choice of design factors employed. It is shown that the scanning-slit, linear-detector-array approach employed can, with available x-ray tube technology, achieve a spatial resolution of 1 cy/mm and detector radiation levels comparable with those obtained with conventional screen-film systems. Also discussed are the unit's exposure latitude and its ability virtually to eliminate scatter.

Computers↗

PubMedDate not supplied

Measured performance characteristics of a solid-state linear detector array.

Experimental studies of a solid-state linear detector array developed for a prototype scanning slit digital chest radiographic unit have been completed. The detector consists of a strip of scintillating material, optically coupled to a linear silicon photodiode array. Measured performance characteristics of the detector, such as sensitivity, modulation transfer function, and detective quantum efficiency, are presented for several different scintillators. Results indicate that direct x-ray absorption events in the silicon photodiode can degrade detective quantum efficiency. Results also indicate that the inexpensive preamplifier circuits used in the digital chest prototype contribute negligible noise at diagnostic x-ray photon fluence rates.

Mathematics↗

PubMedDate not supplied

A laser-based multiformat camera for medical imaging.

The spatial resolution and contrast resolution required of a multiformat camera (MFC) for medical imaging are discussed. A typical cathode-ray tube (CRT) MFC and a prototype laser MFC are compared based on the following measured quantities: line spread function and associated contrast transfer function, noise characteristics, intensity transfer function (dynamic range), large-area contrast, and film irradiance. The laser MFC is found to provide significantly better performance than the CRT MFC in all of these areas.

Fourier Analysis↗