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Biomedical subjects

K H Thunthy

Publications and source records attributed to K H Thunthy.

At least 37 records · Page 2Linked to original sources
PubMed1986

Sensitometric and image analysis of T-grain film.

The new Kodak T-grain film is the result of a new technology that makes fast films with high image resolution. The purpose of the investigation was to determine the sensitometric properties and image quality of a T-grain film (T-Mat G) and also to compare this film with a green-sensitive orthochromatic film (Ortho G) and a blue-sensitive film (XRP). The criteria for film evaluation were relative speed, average contrast, exposure latitude, and image resolution. The results showed that the T-Mat G film is twice as fast as the X-Omat RP film and, one and one-third times as fast as the Ortho G film. T-Mat G also produces high resolution and high contrast. This is contrary to the widely held notion that speed is inversely proportional to image quality.

Absorptiometry, Photon↗
PubMed1985

A special technique to retrieve images from a dark cephalogram.

A high-density, unreadable cephalogram was made readable by duplicating it at 7 to 10 times the usual ultraviolet light exposure. Soft tissue images were retrieved from a readable cephalogram of normal density by duplicating it at 12 to 20 times the usual ultraviolet light exposure. However, the hard tissue images disappeared in the duplicating process. A correctly made duplicate radiograph had a higher image resolution than the image resolution of the original corresponding high-density radiograph. The difference was not significant clinically.

Absorptiometry, Photon↗
PubMed1984

Effects of solution depletion on films developed in the Peri-Pro automatic processor.

The changes in image quality and archival quality of dental films processed successively at room temperature in a Peri-Pro automatic processor without replenishment were measured. The changes in base-plus-fog density, film density and image contrast were measured for each of four processing solutions. All films to be developed in a solution were processed within 4 1/2 hours. The results cannot be generalized to solutions left overnight in the Peri-Pro processor or to solutions used in other automatic processors at different time-temperature cycles. If about 500 films are to be processed in a single day, the Peri-Pro solution, regular X-Omat, and RP X-Omat without part C are the solutions of choice. If about 1,000 films are to be processed in a single day, the Peri-Pro solution and RP X-Omat solution without part C are the solutions of choice. Only the Peri-Pro solution produced films (the first 600 films) of acceptable archival storage quality.

Radiographic Image Enhancement↗
PubMed1984

Maxillary sinus mucocele. Report of an unusual case.

The maxillary sinus mucocele occupying the entire sinus is rarely reported by dentists. This article discusses one such case diagnosed as an exceptionally large maxillary sinus cyst occupying the whole sinus. Unlike their findings in the medical literature, the authors were unable to find many similar cases reported in the dental literature. The location of these mucoceles necessitates the use of diagnostic radiographs, especially those of the panoramic type. Because etiology is still not fully understood after almost 100 years, the authors suggest and discuss four possible mechanisms of sinus mucocele formation and growth.

Adult↗
PubMed1982

Evaluation of contrast in duplicated radiographs.

This investigation evaluated changes in the contrast of duplicated radiographs made at different ultraviolet light exposures. Increasing ultraviolet light exposure had different effects on the duplicates of originals of different "background" densities. When correctly exposed, a duplicate radiograph enhanced contrast. When originals had the same contrast but different "background" densities, their duplicates did not have the same contrast. It was not possible to duplicate accurately all the different contrasts measured on an original. It was possible, however, to produce duplicates with all contrasts greater than those of the original.

Copying Processes↗
PubMed1982

Sensitometric comparison of dental films of groups D and E.

In early 1981 Kodak introduced into the market Ektaspeed dental film of speed group E, which is more sensitive than Ultra-Speed film of speed group D. This investigation compared the sensitometric properties of Kodak dental films of speed groups D and E. By plotting a graph of density against log relative exposure, the characteristic curves were drawn for the two types of films. The curves showed that film E was approximately twice as fast as film D. A table derived from a mathematical description of the characteristic curves permitted the formulation of exact exposure-multiplying factors for changing from one type of film to another. Both films had almost the same useful density range, but film D had higher average film contrast and lower latitude than film E.

Radiography, Dental↗
PubMed1981

Evaluation of the quality of duplicated radiographs.

This experiment evaluated the image quality of duplicated radiographs made at different ultraviolet light exposures. Image quality was measured in terms of "residual" film fog, film density, mottle, image contrast, and resolution. The "residual" fog density of duplicates decreased with increases in ultraviolet exposures until it was less than the fog density of the original. The density of duplicates decreased with increases in ultraviolet exposures until it leveled off at a certain density, depending on the density of the original film. Mottle was less on lighter duplicates than on darker duplicates. Contrast of duplicates increased initially with increases in ultraviolet exposures and later decreased with further increases in ultraviolet exposures. Resolution of duplicates was nearly the same as the original as long as the duplicate had acceptable "residual" fog density.

Copying Processes↗
PubMed1980

Xeroradiographic burnout of the hyoid bone.

This study shows that, depending on the amount of x-radiation used, a phenomenon called xeroradiographic "burnout" can be produced. Clinical cases are illustrated which show the disappearance of the hyoid bone with excessive amounts of x-radiation. Xeroradiographic "burnout" occurs in the positive as well as in the negative mode.

Aged↗
PubMed1980

Comparison of films processed in automatic and manual processors.

This study compared the quality of Kodak RP X-Omat, Kodak Blue Brand, and Kodak periapical films processed in manual tank. Auveloper, P-10, All-Pro, Philips 810, and RP X-Omat processors. Film quality was evaluated in terms of film fog, image contrast, and resolution. For Kodak RP X-Omat and periapical films, automatic processors produced less film fog and were more consistent in fog production than manual tank processor. The difference in fog production between automatic and manual processors was not clinically significant; indeed, it was visuially undetectable. The difference disappeared when Kodak Blue Brand film was used. For Kodak RPX-Omat and Kodak Blue Brand films, at high film densities, the RP X-Omat processor produced films of the highest image contrast. For periapical films, the manual processor produced the highest image contrast. Image contrast at low densities was nearly the same for all processors. For each type of film, resolution was nearly the same for all processors.

Radiography, Dental↗