Anthony R. Lubinsky

Storage Phosphor System For Computed Radiography: Screen Optics

A model for light scattering and absorption effects is applied to a system for computed radiography in which a turbid photostimulable phosphor is scanned with a laser. The spatial spreading of the laser light and the escape probability of the stimulated light are important in determining system response, and models for their effects are presented. Model calculations of system MTF are compared with measured data.

Storage Phosphor System For Computed Radiography: Destructive Scanning

A particular system for computed radiography uses a photostimulable phosphor which is scanned by a laser that reads and also erases the storage medium. The process of reading and erasing is called destructive scanning, and a model of its effects is presented here. Model predictions of system dc gain vs. scanning exposure for the case of raster scanning with a Gaussian beam are compared with measured data.

High-resolution computed radiography by scanned luminescent toner xeroradiography

A new computed radiography system is described in which a charged selenium photoconductive plate is exposed to x-rays to create an electrostatic latent image, developed with a luminescent toner, and scanned with a stimulating laser beam to produce emitted light, which is filtered and detected. The resulting electronic signals are processed, and converted to hard copy using a laser film printer. The system is characterized by high x-ray sensitivity and by very high spatial resolution, which makes it particularly suitable for applications such as mammography and bone radiography. The image luminescence is bright and its decay time is extremely short, enabling rapid scanning with an inexpensive laser source. Also, the electronic capture of image data permits enhancement of the displayed contrast of image structures by image processing techniques.

Performance analysis of medical x-ray film digitizers

A system model for analyzing degradation in the image quality of a radiograph introduced by a film digitizer is presented. The analysis is an extension of the screen-film model of Shaw and VanMetter (SPIE 454, 128-141(1984)). By combining the screen-film characteristics for specific exam types with the properties (e.g., MTF and NPS) of a particular scanner design, the information transfer of the whole digital system can be determined. As an example, the performance of two typical film digitizers, a CCD-based scanner and a laser-based scanner, are evaluated and compared. Image quality descriptors, such as DQE and NEQ as well as equivalent bandwidth and system aperture, are used for the evaluation. By incorporating the human observers threshold response to changes in noise levels (just noticeable differences), a criterion for negligible loss of image information can be established. This can be very useful for system optimization and determination of design tradeoffs.