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PubMedDate not supplied

Development of a high quality film duplication system using a laser digitizer: comparison with computed radiography.

A high quality film-duplication system was developed in order to improve the image quality of duplicated radiographs and to recover improperly exposed films. The system consists of a laser film digitizer, a laser film printer, a workstation, and a magneto-optical disk. Radiographs are digitized by the laser digitizer, processed by the computer for image enhancement, and then printed on a film by the laser printer. A nonlinear density-correction technique is employed in recovering improperly exposed radiographs using the H&D curve of the screen-film system. Using the new duplication system in our department, the average recovery rate was over 80% for chest and abdominal films rejected due to over- or underexposed. The basic imaging properties of the duplication system were compared with those of a Computed Radiography (CR) system and a conventional screen-film system. For low spatial frequencies, the MTF of the CR system is superior to that of the digital duplication system; however, for high spatial frequencies, the MTF of the duplication system is superior. The noise in the duplication system is about half of that in the CR system.

Biophysical Phenomena↗
PubMed1994

High-sensitivity GafChromic film dosimetry for 125I seed.

The dose response of high-sensitivity GafChromic film to photons from 125I seeds for doses up to 200 Gy was established. The optical densities were measured using two types of densitometers: (a) a Macbeth spot densitometer with broadband light spectrum, and (b) an LKB He-Ne laser scanning microdensitometer with red light of wavelength 632.8 nm. The net optical density was found to be a power function of dose with exponents of 0.858 and 0.997, for the Macbeth and LKB densitometers, respectively. Film sensitivity with the LKB densitometer was about double of that with the Macbeth densitometer. The dose measurements were performed using the high-sensitivity GafChromic films for 125I model 6702 seed in solid water phantom. Each film was positioned parallel to the seed's long axis and centered at the seed's transverse axis. Films were exposed at various distances, ranging from contact to 3 cm from the seed center. The radiation dose delivered to the film center varied from 7 to 50 Gy, depending on the distance. The optical density at the film center was measured using both types of densitometers. Dose conversion was achieved with the established dose response curves for the respective densitometers. The dose values, along the seed's transverse axis obtained using both densitometers, were compared with each other, and also compared with published thermoluminescent dosimeter (TLD) data and Monte Carlo results. General agreement was found. It was concluded that the high-sensitivity GafChromic film measurement is a feasible method for 125I seed dosimetry in solid water phantom.(ABSTRACT TRUNCATED AT 250 WORDS)

Biophysical Phenomena↗
PubMed1995

Tests for evaluating laser film digitizers.

A number of tests to evaluate the image transfer characteristics of laser film digitizers have been developed and these tests have been used to evaluate the performance of a Konica KFDR-S laser film digitizer. These tests were designed to be simple in nature and to use materials readily available in clinical departments. The tests examined (i) the geometric accuracy of the laser film digitizer; (ii) the linearity of the digitizer's characteristic curve; (iii) the temporal/spatial response of the digitizer to abrupt changes in optical density; and (iv) the noise added by the digitizer to the digitized images. The tests were easy to use and could be performed in a short period of time. Results of the tests for the Konica laser film digitizer revealed several problems including minor geometric inaccuracies, structural noise added by a shading correction circuit in the digitizer, and spread of the laser beam before reaching the film plane, possibly caused by the f-theta lens of the digitizer. The light spread made the optical density of small, high density structures measured by the digitizer dependent upon the optical density of the surrounding regions. Therefore, under some circumstances, film digitization with the Konica laser film digitizer could lead to erroneous results. In addition, our measurements suggest that these problems are not unique to the Konica digitizer. Thus, the testing of laser film digitizers is recommended, especially if the digitizer is to be used for quantitative measurements.

Humans↗
PubMed1995

Radiation protection requirements for medical x-ray film.

Previous darkroom shielding requirements for medical x-ray film-assumed that the film should not be exposed to diagnostic x-ray radiation levels greater than 2 microGy (0.2 mR) for the life of the film. Modern medical x-ray films are much less sensitive to ionizing radiation, with most films showing at least an order of magnitude less sensitivity than previously assumed. Conversely, these same films when loaded in cassettes using modern intensifying screens exhibit an order of magnitude greater sensitivity when these cassettes are exposed to ionizing radiation. These data suggest that protection of modern medical x-ray film, stored in a darkroom, may require less shielding than previously assumed. Conversely, film loaded in a cassette will require greater shielding.

Radiation Protection↗
PubMed1996

Sensitometric and image quality performance of "rapid" intraoral film processing techniques.

A number of products are available to dentists for the rapid production of intraoral radiographic films but there is little information on their relative merits. This study evaluated the performance of five "rapid" film processing products commonly used by British dentists in comparison with standard Kodak manual processing. Two Perspex contrast-detail test objects were made in order to investigate threshold contrast. Film speed, film gradient, limiting resolution and threshold contrast results are presented. Rapid processing systems possessed lower film speed when compared with Kodak Ektaspeed film and standard Kodak processing. The speed of E-speed film was found to be lower than that of D-speed film when used with Westone "Rapid X-ray" processing. Overall image quality was generally similar for all film/processing combinations evaluated, with the exception of Nix QP which gave markedly poorer image quality.

Humans↗
PubMedDate not supplied

Managing the film library: what to do until the panacea arrives.

Today's imaging departments are complex and often decentralized. Despite such growth, the film library is often overlooked and minimally planned for. The oversight may come from the anticipation of picture archiving and communications systems (PACS), considered by many to be the panacea for film management, but in reality, still only a concept, or at best, in its early stages. Since most departments do not anticipate going filmless for many years and others expect to continue hard copy imaging at a 20 to 30 percent rate, managing the film library remains an important issue. In general, film librarians' daily work remains labor intensive, despite attempts to automate some tasks. Yet when cutbacks are made, this support staff is often cut. One way to deal with service and expansion issues in the film library is to stop and evaluate the situation, assess the decline in the level of service, and determine what issues need improvement. Managers should gather information, analyze the data and listen to all interested parties to be sure they understand the overall problems, often best done by someone from outside the department. Analyzing and evaluating work processes, even observing the design of work areas, can be useful in understanding productivity inside the department. An invaluable way to gather data is to listen to those who carry out the daily tasks and those who use the services. Until their needs are understood by management, further changes will have minimal success. When a list of issues is assembled, managers should establish a team to review and prioritize them. Team members will need to understand departmental long-term plans before making recommendations. While every library's operations are unique, a key problem remains lost films. Policies and procedures for removing films must come from hospital senior administration, while managing film within the department is everyone's job. With the chaos under control, managers will be ready to face the challenge of electronic imaging.

Efficiency, Organizational↗
PubMed1981

A comparative physical evaluation of four X-ray films.

In this study, four general purpose radiographic films (Agfa Gevaert Curix RP-1, duPont Cronex 4, Fuji RX, and Kodak XRP-1) were compared using three independent techniques. By examining the characteristic curves for the four films, film speed and contrast were compared over the diagnostically useful density range. These curves were generated using three methods: (1) irradiation of a standard film cassette lined with high-speed screens, covered by a twelve-step aluminum wedge; (2) direct exposure of film strips to an electro-luminescent sensitometer; and (3) direct irradiation of a standard film cassette lined with high-speed screens. The latter technique provided quantitative values for film speed and relative contrast. All three techniques provided virtually properly identical results and indicate that under properly controlled conditions simplified methods of film testing can give results equivalent to those obtained by more sophisticated techniques.

Evaluation Studies as Topic↗
PubMed2000

Comparison of sensitometric and diagnostic performance of two films.

The sensitometric properties of Kodak Ektaspeed Plus and Flow E-speed film as well as their diagnostic efficacy for detecting proximal surface caries were compared. Flow and Kodak E-speed films were exposed and processed according to American National Standards Institute and American Dental Association (ADA) specifications, and film speed, contrast, and density of base plus fog were measured. Additionally, 80 premolar and molar teeth were imaged and their proximal surfaces scored by 12 dentists for the presence of caries. The actual depth of the caries was determined by microscopic examination of the teeth after sectioning. Kodak Ektaspeed Plus and Flow E-speed films, although labeled E-speed by the manufacturers, are both slow F-speed films. They have comparable base plus fog densities and comparable contrast curves. Dentists detected carious lesions equally well using both film types. The sensitivity, specificity, accuracy, and receiver operating characteristic area for detecting enamel and dentinal caries were not significantly different between the two films. Kodak Ektaspeed Plus and Flow E-speed films both meet or exceed the ADA performance specifications in terms of sensitometric properties. Both offer equal diagnostic utility for detecting caries.

Absorptiometry, Photon↗
PubMed2002

Pre-clinical performance comparing intraoral film and CCD-based systems.

PURPOSE: The purpose of this study was to compare dental hygiene student radiographic performance using film and charge-coupled device (CCD) systems. Specific objectives were to compare the 1) number of technique errors, 2) error type, 3) retake frequency, and 4) learning experience using both systems. METHODS: Twenty-eight subjects exposed two 18-projection full series, one film-based, and one CCD-based system, on a manikin. One examiner, using standardized image quality criteria, evaluated all images. Each subject was assigned to one of four focus groups. Quantitative data were analyzed using ANOVA and Wilcoxon tests. Emic expressions and percentages were used to report qualitative data with themes supported by performance data. RESULTS: A greater number of technique errors occurred using the CCD system than the film system (p < 0.0001), with vertical angulation being the most common error (53%). Using the film-based system, 66% of the errors were due to incorrect horizontal angulation. Subjects exposed an average of 10 retakes per series using the CCD versus 3 retakes using film. Forty-four percent of the subjects felt their most common CCD errors were film placement and vertical angulation compared to 59% who believed horizontal angulation was the main technique error when using film. Difficulty placing the CCD sensor intraorally was expressed by 74%. The CCD system was reported to be beneficial for teaching theory (67%), with 59% preferring film for learning the psychomotor skill. CONCLUSION: In pre-clinical situations, the CCD system may be an effective tool for teaching technique. Radiographic errors are dependent on the type of image receptor used.

Analysis of Variance↗
PubMed1991

Densitometric evaluation of four rapid dental film processing solutions.

The aim of this study was to evaluate densitometrically four rapid processing solutions for dental films; also to identify those combinations of film, solution and temperature which produced the best results in terms of radiographic contrast and relative film speed at a given temperature. The film types used were Agfa Dentus M2, Flow X-ray and Kodak Ultra-speed while the rapid processing solutions tested were Kolchem Rapid Dev 1, Kolchem Rapid Dev 2, MEMS Ultra-Neg and Siemens Insta-Neg. An aluminium step-wedge was radiographed under standardized conditions. Processing was done manually at 18, 20, 22, 25, 27, 29 and 32 degrees C, the temperatures being controlled with the aid of two Julabo thermostatically controlled immersion circulators, to ensure constant temperatures. Unexposed films were processed at each temperature setting to determine base plus fog values. Densitometric readings were taken using a digital densitometer, and base plus fog values were subtracted from each reading. Radiographic contrast and relative film speed were calculated and the data obtained subjected to statistical analysis using Duncan's Multiple Range Test. It was concluded that Agfa Dentus M2 film processed with Kolchem Rapid Dev 2 at 18 degrees C gave the highest radiographic contrast of 0.44 and relative film speed of 4.36. All base plus fog values were within the acceptable limit of 0.25.

Densitometry↗
PubMed1991

Sensitometric evaluation of some mammographic film-screen combinations.

The rapid expansion of screening and assessment mammography is due in part to recent advances in film and processing technology. This has been facilitated by the achievement of high contrast images at lower radiation dose levels. One of the recognised keys for this advancement has been the adoption of extended processing times when compared to regular radiographic processing. The role of other factors, including film types and development chemistry, have received less attention to the present, but is becoming increasingly important as mammographic film technology progresses. This paper reports on four locally available mammographic films that have been exposed through film screen systems to ascertain sensitometric parameters for a variety of processing conditions. Three development times were used (23, 32 and 42 seconds) in combination with four development temperature (32, 34, 36 and 38 degrees) for each of four different chemistries. The results indicate that, as expected, development temperature and time play a major role in film contrast and speed. They also show, however, that different film types respond very differently to extended development times and that development chemistries can be critical to optimal film performance.

Evaluation Studies as Topic↗
PubMed1990

[Lead foil artifacts as a result of unintentional bending of dental X-ray films].

The lead foil of dental x-ray film packets may cause a number of artifacts; especially well known are the "tractor treads" and "herringbone patterns" following a backward filmpositioning in the patient's mouth. In the present paper a specific and seldomly occurring lead foil artifact is described which is caused by bending of the film packet. Four cases collected over a 5-year period are presented. Although different the four cases show a number of similarities. They appear as radiopaque areas covering the upper or lower halves of the films. Their borders show the characteristic "sandbar-pattern" previously described by the author. The explanation of their origin is that the patient has been occluding on a part of the film packet which has been bent to a nearly horizontal position. The x-rays directed against the edge of the lead foil will be absorbed causing irregular radiopaque areas on the film lined by "sandbar-pattern". When the film packet is bent, the lead foil will be stretched and drawn a little away from the edges of the films. Consequently the x-rays will be able to expose the edges of the films. Irregularities of the foil will give rise to concentric "bars". The lead foil is only of limited radiopacity, but due to the oblique direction of the x-rays through the foil the absorbing effect is intensified.

Diagnostic Errors↗
PubMed1985

[Test report on the system components for film processing by the middle-format technology].

Industrially developed accessories for use with medium-format equipment, which have been tested in a-clinical settery, were evaluated separately. The automatic mounting system (Delcadro) with the plastic mount (Cadrix) was accepted by all of our colleagues, and was rated as an advantage, with hardly any reservations. A slight modification is needed in the design of the mounts. This equipment would be a desirable addition to our own equipment for routine work. The daylight system (camera magazine and feeder) is, in principle, certainly a step in the right direction. Handling of the magazine proved to be too complicated and it was prone to malfunctions. Simplification, especially of the loading mechanism, would be desirable. The film feeder is designed for use with conventional roll processing machines. In our opinion, a feeder will always be put to full use if the films processed in this machine are mainly or exclusively of middle format; the darkroom is not permanently staffed and/or adaptation to an existing daylight system (large formats) has already been effected and/or depending on availability, both large and medium size-formats can be processed fully automatically as quickly as possible. However, if films of various formats are processed by an assistant in a darkroom, it is possible to deal with the total quantity of films faster than with a feeder by inserting 3 or 4 medium-format films (or 2 or 3 large-format films) simultaneously. The Heliomat film viewer offers impressive reproductions of 100 mm film on a glare-free glass screen.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed1998

Digital film processing: a comparison of wet and dry processing methods.

Traditional film-based imaging has always relied on film processing that uses liquid chemicals--a method sometimes referred to as wet film processing. As digital imaging has become available for modalities ranging from radiography to magnetic resonance imaging, however, a digital-based processing method called dry film processing has been devised. Dry film processing transfers digital information to film using heat or a combination of heat and light, and the images are processed by the films themselves. In this article, we present an overview of each film processing method, along with a comparison between the methods as they are used by laser imagers and other imager types.

Diagnostic Imaging↗
PubMed1997

Intraalveolar bubbles and bubble films: III. Vulnerability and preservation in the laboratory.

BACKGROUND: Having confirmed (Scarpelli et al. 1996. Anat. Rec. 244:344-357 and 246:245-270) the discovery of intraalveolar bubbles and films as the normal anatomical infrastructure of aerated alveoli at all ages, we now address three questions. Why have these structures been so elusive? Visible in fresh lungs from the in vivo state, can they be preserved by known laboratory methods? Can they be preserved intact for study in tissue sections? METHODS: Lungs of adult rabbits and pups were examined in thorax directly from the in vivo state to confirm normal bubbles both at functional residual capacity and at maximal volume; other lungs were permitted to deflate naturally to minimal volume. The fate of bubbles in situ (either intact, transected, or diced lung tissue) and of isolated bubbles was assessed (1) during conventional histopreparative processing, (2) during inflation-deflation after degassing, (3) after drying in air, (4) during and after quick freezing in liquid N2, and (5) after preservation in fixed and stained tissue sections prepared by a new double-impregnation procedure in which glutaraldehyde-fixed tissue was preembedded in agar, dehydrated and clarified chemically, embedded in paraffin, sectioned, and stained. Control studies included both blocking of bubble formation by rinsing the air spaces with Tween 20 prior to double impregnation and preparation of normal tissue without preembedding in agar. RESULTS: (1) Each of the following procedures in conventional processing dislocated and disrupted bubbles and films: osmium tetroxide and glutaraldehyde:formaldehyde:tannic acid mixture fixation; chemical dehydration (70-100% ethanol) and clarification (xylene and acetone); and embedding in paraffin or epoxy resin. Transection and dicing of the tissue aggravated the untoward effects. In contrast, bubbles and films remained stable in either glutaraldehyde or formaldehyde, which, however, did not protect against the other agents. (2) Degassing destroyed all bubbles as expected; however, bubbles and films re-formed immediately with reinflation. (3) Topography of fixed bubbles and films was retained after air drying. The dry polygonal configuration reverted to spherical-oval either in saline solution or in 50% ethanol, whereas vulnerability to upgraded ethanol concentrations was unchanged. (4) Normal topography and shape appeared to be retained during quick freezing and after thawing. (5) Intraalveolar and intraductal bubbles and films were preserved and photographed in sections from tissue prepared by the double-impregnation procedure; they were not seen either when bubble formation had been blocked (double-impregnation procedure) or when preembedding in agar had been omitted. CONCLUSIONS: (1) Whether or not fixed in glutaraldehyde or formaldehyde, preservation of intraalveolar and intraductal bubbles and films is not to be expected in tissue prepared by conventional histopreparative procedures, whereas product artifacts may be expected from bubble rupture in situ. (2) Degassing cannot be recommended for studies of alveolar structure-function interrelations because all natural bubbles are disrupted in the process, and bubble re-formation may not parallel their "natural history" in vivo. (3) Compared with glutaraldehyde or formaldehyde fixation, air drying offers no added protection against the untoward effects of conventional processing. (4) Quick-frozen tissue is equally at risk. (5) A new double-impregnation procedure does preserve bubbles and films during processing, sectioning, and staining.

Air↗
PubMed1997

Corrosion resistance for biomaterial applications of TiO2 films deposited on titanium and stainless steel by ion-beam-assisted sputtering.

The high corrosion resistance and good biocompatibility of titanium and its alloys are due to a thin passive film that consists essentially of titanium dioxide. There is increasing evidence, however, that under certain conditions extensive titanium release may occur in vivo. An ion-beam-assisted sputtering deposition technique has been used to deposit thick and dense TiO2 films on titanium and stainless steel surfaces. In this study, using the following measurements these TiO2 films have been investigated in a phosphate-buffered saline solution: (1) open-circuit potential versus time of exposure, (2) electrochemical impedance spectroscopy, (3) potentiodynamic polarization, and (4) Mott-Schottky plot. A higher electrical film resistance, lower passive current density, and lower donor density (in the order of 10(15) cm-3) have been measured for the sputter-deposited oxide film on titanium in contrast to the naturally formed passive oxide film on titanium (donor density in the order of 10(20) cm-3). The improved corrosion protection of the sputter-deposited oxide film can be explained by a low defect concentration and, consequently, by a slow mass transport process across the film. As opposed to TiO2 on titanium, a deviation from normal n-type semiconducting Mott-Schottky behavior was observed for TiO2 on stainless steel.

Biocompatible Materials↗
PubMed1998

A complete characterization of Ca5(PO4)3OH sputter-deposited films by ion beam analysis: RBS and ERD.

RF magnetron sputter deposition was used to deposit thin calcium phosphate (hydroxyapatite) layers on titanium alloy substrate material. We determined the precise amount of calcium, phosphorus, oxygen, and hydrogen in these films by combining two ion-beam analysis techniques: Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD). Variables were power level, partial oxygen pressure, or additional water vapor. Also examined was the influence of additional bias power to the substrates during deposition and the effect of annealing on the final composition of the deposited layers. Measurements showed that the Ca/P ratio decreased with increasing oxygen pressure or decreasing sputtering power. In addition, the Ca/P ratio increased when a bias was applied to the substrates. The O/P ratio of the films decreased with additional oxygen pressure but increased when additional water vapor was applied during deposition. All as-deposited films showed a higher hydrogen content than stoichiometric HA. The hydrogen content in the films deposited with water vapor was more than 7 times higher than in the films deposited under pure argon conditions. After annealing, the hydrogen content decreased to about 3.5 at % whereas in stoichiometric HA the hydrogen content amounts to 4.5 at %. After annealing, the oxygen concentration in the film also decreased. We assume that hydrogen disappears out of the film as H2O during annealing. For the targets used in these experiments, sputter deposition at 400 W, with additional water vapor and annealing at 500 degrees C, produced films with a stoichiometry closest to that of hydroxyapatite.

Biocompatible Materials↗
PubMed2003

Correlation of molecular assembly and interactions in crystals and Langmuir-Blodgett films of N-(2,4-dinitrophenyl)-n-octadecylamine.

Correlation of molecular organization in crystals and in ultrathin films is of fundamental interest in the design of molecular materials based on thin films. We have chosen as a test case, N-(2,4-dinitrophenyl)-n-octadecylamine (DNPOA), a potential candidate for the fabrication of Langmuir-Blodgett (LB) films for quadratic nonlinear optical applications. Like several other 4-nitroaniline derivatives, DNPOA does not form stable monolayers at the air-water interface. This has precluded investigations of their organization in LB films. We have stabilized composite Langmuir films of DNPOA with the phospholipid molecule DSPC and fabricated their LB films. Successful growth of single crystals of DNPOA allowed structure determination and detailed analysis of molecular associations in the solid state. Electronic absorption spectra of DNPOA in solution, in the solid state and in the LB film are investigated. Modeling of the various spectral signatures by semiempirical computations on molecular clusters extracted from the crystal lattice provides insight into the correlation between the molecular organization in crystals and in LB films.

Journal Article↗