Raymond P. Rossi

An evaluation of rare earth screen/film combinations.

The physical and imaging characteristics of a number of commercially available rare earth screen/film combinations were evaluated and compared to those of conventional calcium tungstate/X-Omat RP-14 systems. All systems were evaluated for base-plus-fog density, relative speed, resolution, noise, and overall performance. The results indicate that despite certain limitations, rare earth screen/film combinations offer significant advantages for imaging.

A Variable Aperture Fluoroscopic Unit for Reduced Patient Exposure

A real time fluoroscopic imaging system which provides capability for reduced patient exposure by as much as a factor of five has been developed. Modifications to the system include the incorporation of a variable aperture iris between the image intensifier output phosphor and television camera and the use of the video signal as the feedback element in the fluoroscopic automatic exposure rate control system. Quantitative and qualitative performance of the system is described.

Broad beam transmission properties of some common shielding materials for use in diagnostic radiology

Broad beam geometry was used to measure the x-ray transmission properties of gypsum wallboard, steel, plate glass, and concrete for x-ray tube potentials of 50-125 kVp using an x-ray generator having a three-phase, twelve-pulse waveform and total initial beam filtration sufficient to provide half-value layers representative of those found in common practice and required by regulatory agencies. Measurement results are presented graphically and as numerical fits to a mathematical model of broad beam transmission to permit their use in the design of protective barriers for medical diagnostic x-ray facilities.

Radiation exposure in radiographic examinations of the newborn.

Radiation exposure of the newborn during routine chest and abdominal radiographic examinations has been determined. The exposure has been measured at sites representing the entrance and exit chest, entrance, midline, and exit abdomen, the gonads, and the thyroid. Results of these measurements are reported as a function of kVp and in terms of mR received at the anatomical site per mR output of the generator at 24 in. (61 cm). This reporting procedure facilitates application of the results to exposure estimates under similar conditions at other institutions.

Performance Specifications for Diagnostic X-Ray Equipment

The specification of performance characteristics for diagnostic x-ray equipment involves an interplay between purchaser and supplier which often results in inadequate understanding of imaging requirements by the supplier, and unfulfilled expectations by the purchaser. A statement of performance specifications has been prepared and accompanies requests for bids distributed to suppliers. The statement is described in its general form; modifications bay be needed to adapt it to a specific radiographic system.

The Exchange Of Information Between the Purchaser and Supplier of Radiologic Imaging Equipment

As radiologic imaging systems continue to increase in sophistication and cost, and as the complexity and diversity of procedures performed with the systems continue to expand, both the purchaser and supplier of radiologic equipment find themselves in a quandry. How can these individuals he sure a given piece of enuipment will fulfill the demands made of it in the clinical environment? All too frenuently, a lack of understanding of technical equipment specifications by the purchaser, and an unfamiliarity with specific imaging requirements hy the supplier, combine to produce overexpenditures for radiologic equipment and unfulfilled expectations of eguipment performance. To reduce the frequency of these undesirable results, an extensive interchange of information is required between the purchaser and the supplier of radiologic equipment.

Determination Of High-Intensity X-Ray Spectra

A method for determining high intensity x-ray spectra from diagnostic x-ray units is described. The method combines direct measurements of low intensity, constant potential x-ray spectra with digitized measurements of current and voltage waveforms at high intensity to determine high intensity x-ray spectra. The effect of ripple in the voltage waveform on the resulting x-ray spectra is also shown.

Acceptance Testing and Performance Monitoring of Radiographic Phototimers

A protocol for acceptance testing and performance monitoring of radiographic phototimers is described, together with results obtained during application of the protocol to evaluation of the response characteristics of phototimers on two new x-ray generators.

Performance Specifications For Diagnostic Radiologic Equipment: A Delicate Interface Between Purchaser And Supplier

The specification of performance characteristics for a diagnostic radiologic imaging system involves an interplay between purchaser and supplier which often results in inadequate understanding of the imaging requirements by the supplier, and unfulfilled expectations of the imaging system by the purchaser. To diminish the impact of these results, the communicative linkage between supplier and purchaser should be as strong as possible during the development of performance specifications and acceptance testing protocols for the imaging system. As an aid in establishing this linkage, we have developed a statement of performance specifications which accompanies requests for bid proposals distributed to suppliers of diagnostic radiologic equipment. This statement is presented here in its general form; certain modifications may be necessary in its adaptation to any specific radiologic imaging systems.

Field Evaluation Of Radiographic Phototimers

A protocol for acceptance testing and performance monitoring of radiographic phototimers is described, together with results obtained during application of the protocol to evaluation of the response characteristics of phototimers on two new x-ray generators.