[Dosimetry of roentgen & gamma rays by means of photographic films. 2. Application to film dosimetry. III. Sources of error in film dosimetry].
Explore the source record for details and available documents.
Film Dosimetry↗
SEARCH · PubMed Health
Results for “Films”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[On the problem of the use of film-screen combinations consisting only of film and back screen instead of film without screens (author's transl)].
Explore the source record for details and available documents.
Film Dosimetry↗
Laser-tissue soldering with biodegradable polymer films in vitro: film surface morphology and hydration effects.
BACKGROUND AND OBJECTIVE: Previous research introduced the concept of using biodegradable polymer film reinforcement of a liquid albumin solder for improvement of the tensile strength of repaired incisions in vitro. In this study, the effect of creating small pores in the PLGA films on the weld breaking strength is studied. Additionally, the effect of hydration on the strength of the reinforced welds is investigated. STUDY DESIGN/MATERIALS AND METHODS: A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with an 806-nm CW diode laser. A poly(DL-lactic-co-glycolic acid) (PLGA) film was used to reinforce the solder (the controls had solder but no reinforcement). Breaking strengths were measured acutely and after hydration in saline for 1 and 2 days. The data were analyzed by ANOVA (P < 0.05) and multiple comparisons of means were performed using the Newman-Keuls test. RESULTS: The creation of pores in the PLGA films qualitatively improved the film flexibility without having an apparent adverse effect on the breaking strength, while the actual technique of applying the film and solder had more of an effect. The acute maximum average breaking strengths of some of the film reinforced specimens (114.7 g-134.4 g) were significantly higher (P < 0.05) than the acute maximum average breaking strength of the unreinforced control specimens (68.3 g). Film reinforced specimens were shown to have a statistically significantly higher breaking strength than unreinforced controls after 1- and 2-day hydration. CONCLUSIONS: Reinforcement of liquid albumin solders in laser-assisted incision repair appears to have advantages over conventional methods that do not reinforce the cohesive strength of the solder in terms of acute breaking strength and after immersion in moist environments for short periods of time. Using a film with the solder applied to one surface only may be advantageous over other techniques.
Animals↗
Cognitive engineering of film library transition from film medium to digital environment in a Texas teaching hospital.
Digital imaging technology promises efficient, economical, and fast service for patient care, but the challenges are great in the transition from film to a filmless (digital) environment. This change has a significant impact on the film library's personnel (film librarians) who play a leading roles in storage, classification, and retrieval of images. The objectives of this project were to study film library errors and the usability of a physical computerized system that could not be changed, while developing an intervention to reduce errors and test the usability of the intervention. Cognitive and human factors analysis were used to evaluate human-computer interaction. A workflow analysis was performed to understand the film and digital imaging processes. User and task analyses were applied to account for all behaviors involved in interaction with the system. A heuristic evaluation was used to probe the usability issues in the picture archiving and communication systems (PACS) modules. Simplified paper-based instructions were designed to familiarize the film librarians with the digital system. A usability survey evaluated the effectiveness of the instruction. The user and task analyses indicated that different users faced challenges based on their computer literacy, education, roles, and frequency of use of diagnostic imaging. The workflow analysis showed that the approaches to using the digital library differ among the various departments. The heuristic evaluation of the PACS modules showed the human-computer interface to have usability issues that prevented easy operation. Simplified instructions were designed for operation of the modules. Usability surveys conducted before and after revision of the instructions showed that performance improved. Cognitive and human factor analysis can help film librarians and other users adapt to the filmless system. Use of cognitive science tools will aid in successful transition of the film library from a film environment to a digital environment.
Cognitive Science↗
Electrochemically deposited organic luminescent films: the effects of deposition parameters on morphologies and luminescent efficiency of films.
The electropolymerization behaviors of an electroactive and luminescent compound TCPC as precursor are studied. The resultant electrochemical deposition (ED) films are characterized by cyclic voltammetry (CV), UV-vis, fluorescence spectra, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Under the CV mode with potential range of -0.5 to 0.85 V vs Ag/Ag(+), the coupling reactions between the carbazole units of TCPC are very efficient, while the fluorescent trifluorene segment in TCPC is chemically inert in this potential range, which results in a highly fluorescent film formation on indium tin oxide (ITO) electrode. The deposition parameters for preparing the TCPC-based ED films are optimized, and the best ED film gives the fluorescence efficiency of 45.5% with surface roughness of 2.8 nm and morphologic stability as heating to 180 degrees C. The light-emitting devices (LEDs) using this ED film as light emitting layer with structure ITO/ED film (approximately 100 nm)/Ba/Al achieve maximum luminescence and external quantum efficiency of 4224 cd/m(2) at 17 V and 0.72% at 11.5 V, respectively, which are better than the device using TCPC spin-coating films as emitting layer. The technique provides a facile route toward a patternable luminescent film and device because such luminescent ED films can be manipulatively deposited on the electrified electrode.
Journal Article↗
Corn starches as film formers in aqueous-based film coating.
The purpose of this study was to evaluate the film formation ability and mechanical stress-strain properties of aqueous native corn starches, using free films and film coatings applied to tablets. Free films were prepared from high-amylose corn (Hylon VII), corn and waxy corn starches, using sorbitol and glycerol as plasticizers. The tablets and pellets were film-coated using an air-suspension coater, and characterized with respect to the film coating surface topography, cross-sectional structure and thickness (SEM), and dissolution in vitro. The amylose content of the starch film formers affected both the tensile strength and the elongation. The elongations were under 5% for even the plasticized starches, and in most cases, no plasticization effect was seen by either of the plasticizers. Dissolution of native corn starch film-coated tablets (weight gain 1%) did not differ from uncoated ones. A notable delay in dissolution of the drug was found by increasing Hylon VII film coating thickness, suggesting controlled-release characteristics.
Amylose↗
Mammographic microcalcifications: detection with xerography, screen-film, and digitized film display.
Pulverized bone specks and aluminum oxide specks were measured by hand into sizes ranging from 0.2 mm to 1.0 mm and then arranged in clusters. These clusters were superimposed on a human breast tissue phantom, and xeromammograms and screen-film mammograms of the clusters were made. The screen-film mammograms were digitized using a high-resolution laser scanner and then displayed on cathode ray tube (CRT) monitors. Six radiologists independently counted the microcalcifications on the xeromammograms, the screen-film mammograms, and the digitized-film mammograms. The xeromammograms were examined with a magnifying glass; the screen-film images were examined with a magnifying glass and by hot light; and the digitized-film images were examined by electronic magnification and image processing. The bone speck size that corresponded to a mean 50% detectability level for each technique was as follows: xeromammography, 0.550 mm; digitized film, 0.573 mm; and screen-film, 0.661 mm. We postulate that electronic magnification and image processing with edge enhancement can improve the capability of screen-film mammography to enhance the detection of microcalcifications.
Breast Diseases↗
Unified analysis and mathematical representation of film-thickness behavior of film-substrate systems.
The ellipsometric function p of a film-substrate system is studied as the film thickness d is kept constant and the angle of incidence phi is changed. The generated constant-thickness contours (CTCs) are characterized by an introduced mathematical behavior indicator that represents a group of CTCs. The behavior of each group is developed and studied in the four planes phi-d, X, Z, and p, where X is the film-thickness exponential function and Z is a previously introduced intermediate plane. In the phi-d plane the film-thickness domain is identified and divided into a sequence of disconnected thickness subdomains (DTSs), depending on only N0 and N1, and their number depending on the range in which N0/N1 lies. The behavior of the CTCs in the successive planes X, Z, and p is then studied in each DTS, and the CTC's space is divided into disconnected subfamilies according to the behavior indicator. Equivalence classes that reduce the infinite number of subfamilies into a finite number are then introduced. The transformation from each plane to the next is studied with the origin of the Z plane mapped onto the point at infinity of the p plane, forming a singularity. A multiple-film-thickness inequality is derived to determine the unique solution of the film thickness. The type of reflection being internal or external at both ambient-film and film-substrate interfaces affects the analysis and is also considered. To conclude we introduce the design of polarization-preserving devices and a novel oscillating single-element ellipsometer to fully characterize zero film-substrate systems as examples of applying the knowledge developed here.
Journal Article↗
Salivary films on hydroxyapatite studied by an in vitro system for investigating the effect of metal ions and by a quartz-crystal microbalance system for monitoring layer-by-layer film formation.
The salivary film or the acquired pellicle is a protein film formed initially on the enamel surface of teeth. Such a film plays an important role in enamel protection, but is also an initial substructure for the formation of plaque and the cosmetically undesirable colored stain. The composition and the structure of the film are still essentially unknown because of the difficulty of its isolation for characterization. The purpose of this study was to investigate the effect of some metal cations on the salivary film or the pellicle formation, and also to clarify the mechanism of development. First, using infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS), the in situ-formed film in the mouth was confirmed to contain selectively adsorbed well-known proteins. Then, in vitro studies have demonstrated that Ca2+ ions enhance film formation at the initial stage in virtue of Ca bridging and, interestingly, that Mg2+ ions oppositely inhibit the formation. Furthermore, the quartz-crystal microbalance (QCM), utilized successfully for the first time to study the salivary film, has shown the possibility of an alternate accumulation mechanism by which the surface charges on the film are effectively reversed by the opposite charged proteins.
Durapatite↗
Is E-speed dental film more sensitive to storage than D-speed dental film?
Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed), were compared regarding film fogging under different storage conditions. The films were stored during one year at room temperature (+21 degrees C) without shielding, with 3 mm lead or with 200 mm iron shielding and in a refrigerator (+8 degrees C) without shielding. The films were processed in a standardised way and the film fog measured densitometrically each month. The film fog increased insignificantly with time for both film types under all storage conditions except in the refrigerator, where it reached unacceptably high levels and the faster film type (Kodak Ektaspeed) became unusable after 4 months storage in the refrigerator.
Radiography, Dental↗
Relationship of film properties to drug release from monolithic films containing adjuvants.
The rate of drug release from a polymeric matrix system was influenced by the physical and chemical properties of the monolithic films. The model drugs, salicylic acid and chlorpheniramine maleate, and two poly(methyl methacrylate) copolymers of different permeabilities (Eudragit RL and Eudragit RS), with and without additional adjuvants, were used to form monolithic matrix films for controlled drug release. Adjuvants, including polyethylene glycols (PEG 400 and PEG 8000) and poly(vinylpyrrolidones) (PVP-K15 and PVP-K90), were incorporated into films of Eudragit RL PM and Eudragit RS PM. The moisture permeation constant, glass transition temperature (Tg), tensile strength, and drug release profiles were determined for each acrylic resin slab to correlate the physicochemical and physicomechanical film properties to observed drug release. Faster rates of drug diffusion were observed with the addition of PEG 400 to the films, because of its plasticizing effect and the resultant increased moisture permeability of the matrix. An exception existed with the Eudragit RL PM film containing salicylic acid where drug-polymer interactions inhibited drug diffusion. The small changes in moisture permeability, Tg, and tensile strength observed with incorporation of the PVPs had an insignificant influence on the dissolution results for salicylic acid from Eudragit RS PM films. Increases in the tensile strength and Tg after addition of PVP to the Eudragit RS PM matrix support the observed decreased rate of diffusion for chlorpheniramine maleate. The pores formed by migration of the hydrophilic adjuvants from the films altered the diffusion kinetics of the matrix, compared with that of the nonporous polymer, when only the antihistamine was present.
Acrylic Resins↗
Effect of film composition and various penetration enhancers concentrations on prazosin release from acrylic polymeric films.
An investigation was conducted to evaluate the effect of changing the Eudragit RL 100 ratio and the influence of different penetration enhancers in various concentrations on the release of prazosin from Carboset 525:Eudragit RL 100 polymeric films using improved Franz diffusion cells, to choose the most suitable polymeric film ratio, the most appropriate enhancer and its optimum concentration to be used to achieve the maximum release of the drug. The results show that prazosin release from polymeric films containing Carboset 525:Eudragit RL 100 in a 1:1 ratio was significantly (p < 0.05) higher than from films in a 1:0.25 ratio and non-significantly (p > 0.05) higher than from those containing 1:0.5, 1:3 polymer ratios and non-significantly lower from those containing 1:4 polymer ratios. The addition of various enhancers, n-decyl alcohol (7, 9 and 11% w/w), Azone (4, 6 and 8% w/w) and Cineole (7, 9, 11 and 14% w/w) significantly (p < 0.05) enhanced the prazosin release from these polymeric films containing the two polymers in a 1:1 ratio. The best concentrations of these enhancers were 11% n-decyl alcohol, 9% Cineole and 8% Azone. The formulations containing these concentrations of the enhancers are being further studied for drug release through rabbits skin. It was found that using either of these enhancers in these concentrations resulted in a significant (p < 0.05) increase in the amount of prazosin transported across the skin. On the other hand these enhancers did not show any significant (p > 0.05) difference between them. The mechanism of drug release from the polymeric films was further studied using water vapor permeability (W.V.P.), the permeability constant (P) and differential scanning calorimetry. The enhancers were found to increase the W.V.P. and the permeability constant (P) and the results were in very good agreement with the effect of enhancers on the in-vitro drug release. The DSC thermograms showed that the enhancers physically interacted with either or both of the polymeric film materials and prazosin which could be one of the reasons for the improvement in the release of the drug from these polymeric films.
Acrylic Resins↗
Molecular basis of film formation from a soybean protein: comparison between the conformation of glycinin in aqueous solution and in films.
Fourier transform infrared spectroscopy has been used to investigate the conformational changes of glycinin. a major storage protein of soybean seeds, upon film-forming. The results show that the secondary structure of glycinin is mainly composed of a beta-sheet (48%) and unordered (49%) structures. The amide I band of glycinin in film-forming conditions, i.e. in alkaline media and in the presence of plasticizing agent, reveals the conversion of 18% of the secondary structure of the protein from the beta-sheet (6%) and random coil (12%) to the alpha-helical conformation due to the helicogenic effect of the ethylene glycol used as the plasticizing agent. Conformational changes also occur upon the film-forming process leading to the formation of intermolecular hydrogen-bonded beta-sheet structures. Results obtained from other plant families indicate that, whatever the origin and conformation of protein, formation of films leads to the appearance of intermolecular hydrogen-bonded beta-sheet structures, suggesting that this type of structure might be essential for the network formation in films. Thus, it is hypothesized that, in the film state, intermolecular hydrogen bonding between segments of beta-sheet may act as junction zones in the film network. This study reveals for the first time that there is a close relationship between the conformation of proteins and the mechanical properties of films.
Globulins↗
Plasma-induced graft polymerization of acrylic acid onto poly(ethylene terephthalate) films: characterization and human smooth muscle cell growth on grafted films.
Graft polymerization of acrylic acid onto plasma treated poly(ethylene terephthalate) (PET) films was carried out to develop surfaces for protein immobilization and smooth muscle cell seeding. Films with various graft densities were characterized by contact angle measurements, attenuated total reflectance infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The contact angle was observed to decrease from 72.9 degrees for the virgin PET films to between 26 degrees and 33 degrees depending on the graft density. Storage of grafted films led to an increase in the contact angle, suggesting molecular rearrangement at the surface. However, films with the lowest graft levels showed maximum enhancement in the contact angle up on storage. XPS confirmed the presence of the polyacrylic acid grafts at the film surface and AFM showed a marked increase in the wavelength of the surface roughness as the graft density increased. The amount of collagen immobilized at the surface of the grafted films also increased as the graft density increased. The collagen immobilized films provided an excellent substrate for the growth of human smooth muscle cells.
Acrylates↗
Finite element analysis of slow drug release through deformed coating film: effects of morphology and average thickness of coating film.
This paper, a continuation of our previous work, is a presentation of the effect of the morphology and the average thickness of the deformed coating films on the slow diffusional release characteristics analyzed numerically under the constraints of the constant volume of the drug matrices and the coating films, if the films have the same average thickness. Increasing the average thickness of the coating films slows down the fractional release and the average release rate of the drug and smoothen the initial burst of the drug, as well as increase the initial lag time. The effect due to deformation of the coating films on these diffusional release characteristics are found to be less significant with the increasing average thickness of the coating films. Interestingly initial lag times are found to be the same for the coated particles having the same smallest thickness but different average thickness of coating films. The effect due to the change in the average thickness of the coating films on the characteristics of the slow controlled-release is discussed to shed light on the design of a better controlled-release device.
Algorithms↗
Electrochemically deposited sol-gel-derived silicate films as a viable alternative in thin-film design.
Sol-gel-derived silicate films were electrochemically deposited on conducting surfaces from a sol consisting of tetramethoxysilane (TMOS). In this method, a sufficiently negative potential is applied to the electrode surface to reduce oxygen to hydroxyl ions, which serves as the catalyst for the hydrolysis and condensation of TMOS. The electrodeposition process was followed by the electrochemical quartz crystal microbalance and cyclic voltammetry. The electrodeposited films were characterized for their surface morphology, porosity, and film thickness using atomic force microscopy, electrochemical probe techniques, surface area and pore size analysis, and profilometry. The electrodeposited films were found to have a completely different surface structure and to be significantly rougher relative to spin-coated films. This is likely due in part to the separation of the gelation and evaporation stages of film formation. The electrodeposited films were found to be permeable to simple redox molecules, such as ruthenium(III) hexaammine and ferrocene methanol. Film thickness can be easily varied from < 75 nm to > 15 microm by varying the electrode potential from -600 mV to more than -1000 mV, respectively. The electrodeposition process was further applied for the electroencapsulation of redox molecules and organic dyes within the silicate network. Cyclic voltammograms for the gel-entrapped ferrocene methanol (FcCH2OH) and ruthenium(II) tris(bipyridine) (Ru(bpy)3(2+)) exhibited the characteristic redox behavior of the molecules. The electroencapsulation of organic dyes in their "native" form proved to be more difficult because these species typically contain reducible functionalities that change the structure of the dye.
Journal Article↗
Observation of the anisotropic photoinduced magnetization effect in Co-Fe Prussian blue thin films fabricated by using clay Langmuir-Blodgett films as a template.
Thin films of cobalt-iron cyanide (Co-Fe Prussian blue) have been fabricated by means of the modified Langmuir-Blodgett (LB) method using a smectite clay mineral (montmorillonite). In this combined method, clay LB films play a template role in the formation of the Co-Fe Prussian blue thin layer. The films were revealed to possess a well-organized structure not only in perpendicular directions to the film surface but also in parallel directions to the film surface. The photoinduced electron transfer from the iron ion to the cobalt through the bridging cyanide in the films occurred at low temperature (8 K), similar to that in the bulk Co-Fe Prussian blue. The films clearly exhibited magnetic anisotropy with regards to the direction of the applied magnetic field. Moreover, the photoinduced magnetization effect in the films was also found to be anisotropic.
Journal Article↗
Fabrication of nanoparticulate porous LaOF films through film growth and thermal decomposition of ion-modified lanthanum diacetate hydroxide.
This paper first reports fabrication of macro/nanotextured rare-earth oxyfluoride films. Usage of ion-modified lanthanum diacetate hydroxide (LDAH) as self-templates was successful in producing nanoparticulate lanthanum oxyfluoride (LaOF) films. LDAH template films were deposited on glass substrates through a chemical bath deposition in solutions composed of lanthanum acetate sesquihydrate, methanol, trifluoroacetic acid, and aqueous ammonia. The LDAH films had a unique, nestlike morphology owing to a two-dimensional hexagonal crystal growth. Modification of LDAH with trifluoroacetate ions led to formation of LaOF after pyrolyzing the template films at temperatures of 400-600 degrees C in air. The resultant LaOF films had a nanoparticulate porous microstructure, maintaining the morphology of the original LDAH template films. It was also successful to incorporate Eu3+ ions into LaOF through deposition of the LDAH film in a solution containing europium acetate tetrahydrate. The characteristic photoluminescence from Eu(3+) was observed with an ultraviolet-light excitation at 273 nm, indicating that Eu3+ was homogeneously distributed in LaOF host crystals. Thus the ion-modification of LDAH was also demonstrated to be a useful method for preparing nanostructured rare-earth oxyfluoride materials havingvarious cationic compositions.
Journal Article↗