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PubMed1999

Perturbation of radiotherapy beams by radiographic film: measurements and Monte Carlo simulations.

Radiographic film is an established practical tool used in the measurement of the dose distribution for radiotherapy purposes. The accuracy and reproducibility of film optical density as an indicator of dose has been associated with several factors including photon energy, processing conditions and film plane orientation. Few studies have investigated the factors causing variability in film dosimetry, due to the difficulty of separating the individual contributions. The effect that a sheet of radiographic film in a water phantom has on its response to a 6 MV photon and a cobalt-60 teletherapy beam, when orientated perpendicular and parallel to the beam central axis, is reported. Monte Carlo generated spectra were used to calculate collision kerma (Kcoll) for water and film elements. Measured and calculated results indicate a potential over-response at 25 cm depth of the order of 14 +/- 2.4% and 18 +/- 6.0% respectively for 6 MV photons and 15 +/- 3.4% and 32 +/- 4.5% respectively for a cobalt beam. For film exposed parallel as compared to perpendicular to the central axis of the beam, the calculated results suggest an explanation in terms of the predominantly forward directed secondary electrons for the measured difference in film response at depth. It is proposed that the difference in response of the parallel as compared to perpendicular exposed film be due to the predominantly 'upstream' photon interactions giving rise to energy deposition in film. The simulations indicate that the variation with depth of relative energy imparted in film and water elements correlates with the observed variation in film response with depth.

Energy Transfer↗
PubMed2002

Comparative evaluation of Kodak EDR2 and XV2 films for verification of intensity modulated radiation therapy.

Film dosimetry provides a convenient tool to determine dose distributions, especially for verification of IMRT plans. However, the film response to radiation shows a significant dependence on depth, energy and field size that compromise the accuracy of measurements. Kodak's XV2 film has a low saturation dose (approximately 100 cGy) and, consequently, a relatively short region of linear dose-response. The recently introduced Kodak extended range EDR2 film was reported to have a linear dose-response region extending to 500 cGy. This increased dose range may be particularly useful in the verification of IMRT plans. In this work, the dependence of Kodak EDR2 film's response on the depth, field size and energy was evaluated and compared with Kodak XV2 film. Co-60, 6 MV, 10 MV and 18 MV beams were used. Field sizes were 2 x 2, 6 x 6, 10 x 10, 14 x 14, 18 x 18 and 24 x 24 cm2. Doses for XV2 and EDR2 films were 80 cGy and 300 cGy, respectively. Optical density was converted to dose using depth-corrected sensitometric (Hurter and Driffield, or H&D) curves. For each field size, XV2 and EDR2 depth-dose curves were compared with ion chamber depth-dose curves. Both films demonstrated similar (within 1%) field size dependence. The deviation from the ion chamber for both films was small forthe fields ranging from 2 x 2 to 10 x 10 cm2: < or =2% for 6, 10 and 18 MV beams. No deviation was observed for the Co-60 beam. As the field size increased to 24 x 24 cm2, the deviation became significant for both films: approximately 7.5% for Co-60, approximately 5% for 6 MV and 10 MV, and approximately 6% for 18 MV. During the verification of IMRT plans, EDR2 film showed a better agreement with the calculated dose distributions than the XV2 film.

Dose-Response Relationship, Radiation↗
PubMed2001

A comparison of Kodak Ultraspeed and Ektaspeed Plus dental X-ray films for use in endodontics.

BACKGROUND: The advantage of using a faster film for length determination in endodontic therapy is obvious. However, for such a film to be generally accepted, it must demonstrate comparable diagnostic quality to traditionally used films. METHODS: The comparative accuracy of canal length determination of Ultraspeed and Ektaspeed Plus dental X-ray films was assessed in maxillary first and second molars; for different canals, for different teeth, for different exposures, and for different examiners (five general dentists and three endodontic specialists). RESULTS: In general, there were no significant differences between films, among examiners, or any interaction between films and exposures. That is, an assessor's ability to estimate lengths was not significantly influenced by the film type or by exposure used. There was a wide divergence in the individual assessor's ability to estimate lengths. Specialists estimated lengths more accurately than general practitioners and estimated lengths more accurately with Ektaspeed Plus film. Length determination in distobuccal and mesiobuccal canals was more accurate than in palatal canals. Most palatal canals were underestimated in length by more than 1mm. The use of file sizes larger in number than size 15 is recommended in these canals. CONCLUSION: For length determination, Ektaspeed Plus dental X-ray film is as effective as Ultraspeed film. Given the acceptable quality and accuracy of Ektaspeed Plus film, there seems to be no clinical reason to subject patients to greater radiation by using a slower film during endodontic therapy.

Dental Pulp Cavity↗
PubMed2002

A comparison of Kodak Ultraspeed and Ektaspeed plus dental X-ray films for the detection of dental caries.

BACKGROUND: Using the fastest dental X-ray film available is an easy way of reducing exposure to ionizing radiation. However, the diagnostic ability of fast films for the detection of proximal surface caries must be demonstrated before these films will become universally accepted. METHODS: Extracted premolar and molar teeth were arranged to simulate a bitewing examination and radiographed using Ultraspeed and Ektaspeed Plus dental X-ray films. Three different exposure times were used for each film type. Six general dentists were used to determine the presence and depth of the decay in the proximal surfaces of the teeth radiographed. The actual extent of the decay in the teeth was determined by sectioning the teeth and examining them under a microscope. RESULTS: There was no significant difference between the two films for the mean correct diagnosis. However, there was a significant difference between the means for the three exposure times used for Ultraspeed film. The practitioners used were not consistent in their ability to make a correct diagnosis, or for the film for which they got the highest correct diagnosis. CONCLUSIONS: Ektaspeed Plus dental X-ray film is just as reliable as Ultraspeed dental X-ray film for the detection of proximal surface decay. The effect of underexposure was significant for Ultraspeed, but not for Ektaspeed Plus. Patient exposure can be reduced significantly with no loss of diagnostic ability by changing from Ultraspeed X-ray film to Ektaspeed Plus X-ray film.

Dental Caries↗
PubMed2001

Variation of sensitometric curves of radiographic films in high energy photon beams.

Film dosimetry is an important tool for the verification of irradiation techniques. The shape of the sensitometric curve depends on the type of film as well as on the irradiation and processing conditions. Existing data concerning the influence of irradiation geometry on the sensitometric curve are conflicting. In particular the variation of optical density, OD, with field size and depth in a phantom shows large differences in magnitude between various authors. This variation, as well as the effect of beam energy and film plane orientation on OD, was therefore investigated for two types of film, Kodak X-Omat V and Agfa Structurix D2. Films were positioned in a solid phantom, either perpendicular or (almost) parallel to the beam axis, and irradiated to different dose levels using various photon beams (Co-60, 6 MV, 15 MV, 18 MV, 45 MV). It was found that the sensitometric curves of the Kodak film derived at different depths are almost identical for the four x-ray beams. For the Kodak film the differences in OD with depth are less than 2%, except for the Co-60 beam, where the difference is about 4% at 10 cm depth for a 15 cm x 15 cm field. The slope of the sensitometric curve of the Agfa film is somewhat more dependent on photon beam energy, depth and field size. The sensitometric curves of both types of film are almost independent of the film plane orientation, except for shallow depths. For Co-60 and for the same dose, the Kodak and Agfa films gave at dose maximum an OD lower by 4% and 6%, respectively, for the parallel compared to the perpendicular geometry. Good dosimetric results can be obtained if films from the same batch are irradiated with small to moderate field sizes (up to about 15 cm x 15 cm), at moderate depths (up to about 15 cm), using a single calibration curve, e.g., for a 10 cm x 10 cm field.

Biophysical Phenomena↗
PubMed1999

Characterization of the reciprocity law failure in three mammography screen-film systems.

The purpose of this project was to quantify reciprocity law failure (RLF) for mammography screen-film systems. Three widely used screen-film systems were evaluated: the Kodak MinR 2000 system. Fuji UM Mammo Fine screen and Fuji UM MA HC film, and Agfa MR Detail screen and Agfa Mammoray MR5 film. The logit algorithm that linearizes logistic curve shapes was utilized to characterize film sensitometric response. Different values of mammographic phantom thickness, tube current, and kVp were used to vary screen-film exposure rates. RLF was quantified by examining the dependence of logit parameters (maximum and minimum film density, curve shift, and slope) on exposure rate. The shift of the logit curve was found to be a good indicator of the screen-film system speed, while the slope of the logit curve is affected by the RLF. RLF leads to changes in film contrast as well as speed. For the range of exposure rates measured (50-fold), screen-film contrast and speed varied by factors of 2 and 3.5, respectively. Film contrast decreased as exposure rate increased. The greatest changes were observed with the Kodak MinR 2000 screen-film system.

Mammography↗
PubMed2001

Implications of using high contrast mammography X-ray film-screen combinations.

The objective of this study was to determine the implications of using Fuji AD-M and Kodak min-R 2000, two high contrast X-ray film types developed for mammography. Evaluation of the Fuji AD-M film was divided into two parts. The first part was a contralateral comparison between mammograms using Fuji AD-M and Fuji UM-MA HC film-screen combinations. Fuji AD-M contrast was about 25% higher than that of Fuji UM-MA HC. The effect of increased contrast on image quality was investigated by visually grading the quality of information in different parts of each mammogram. Fuji AD-M film was generally judged to be better for overall diagnosis. However, 2.3% of mammograms produced using Fuji AD-M film were not acceptable and might have led to a technical recall of the patient. In the second part of this study, sets of mammograms from women attending mobile screening units were reviewed. One unit used Fuji AD-M film and the other used Kodak min-R 2000 film. Both samples of mammograms were digitized and analysed. The average film gradients between an optical density (OD) of 0.25 and 2.00 above base plus fog were 4.38 for Fuji AD-M film and 3.77 for Kodak min-R 2000 film. The main breast regions of the mammograms were judged to be satisfactorily displayed when breast tissues were above ODs of approximately 0.6 for Fuji AD-M film and 0.8 for Kodak min-R 2000 film.

Adult↗
PubMed1991

Image quality comparisons of X-Omat RP, L and B films.

The Eastman Kodak Company has recently developed a new film, X-Omat B (XB), designed to be interchangeable with X-Omat RP (XRP) film. The manufacturer claims the new film can be manually developed in half the time of other X-Omat films while automatic processing is unchanged. Three X-Omat film types were processed manually or automatically and the image qualities were evaluated. The XRP film had greater contrast than the XB and X-Omat L (XL) films when manually processed, and the XL film showed less contrast than the XB and XRP films when processed automatically. There was no difference in the subjective evaluation of the various film types and processing methods, and the XB film could be interchanged with XRP film in a simulated clinical situation.

Evaluation Studies as Topic↗
PubMed1990

Diagnostic quality of mammograms obtained with a new low-radiation-dose dual-screen and dual-emulsion film combination.

We evaluated the image quality of mammograms made by using a new dual-screen, dual-emulsion film combination (Kodak Min-R Fast screen, T-Mat Mll film) that permits reduction of radiation exposure by approximately 50% when compared with a standard single-screen, single-emulsion film system (Kodak Min-R screen, OM-1 film). This new film has been improved when compared with earlier T-Mat M film, including the introduction of an inert dye to reduce light crossover to essentially 0%. Mammogram pairs made with the dual-emulsion film combination and the standard single-emulsion film combination were obtained in 50 patients otherwise undergoing routine mammography. The image pairs were randomized and evaluated by three radiologists who used a three-point scale (better, same, or worse). Each pair was evaluated with regard to parenchymal contrast, sharpness, and latitude, as well as the number and sharpness of calcifications (n = 19) and sharpness of masses (n = 12) when present. All three observers found the dual-emulsion film combination to be better than or the same as the standard with regard to parenchymal sharpness (94-100%), the number and sharpness of calcifications (98-100%), and sharpness of masses (100%). Two observers found the dual-emulsion film combination to be significantly worse (p less than .05) than the standard with respect to parenchymal contrast (72%, 86%), and all three observers rated it significantly worse for film latitude (14 to 42%). Our results suggest that this new dual-emulsion film combination that allows mammography to be performed with less radiation exposure can be used without loss of image quality.

Breast↗
PubMed1992

Sensitometric comparison of direct- and indirect-exposure films used in intraoral radiography.

In Japan, some dentists use indirect-exposure (screen) films for intraoral radiography, without the use of intensifying screens. The purpose of the present investigation was to determine whether film speed, inherent contrast, and latitude of Japanese indirect-exposure films used without intensifying screens were comparable to those of direct-exposure (non-screen) films used for intraoral radiography. The characteristic curves of Kodak Ektaspeed ("E" speed) and Ultra-speed ("D" speed) films were used as standards for comparison. Indirect-exposure films without intensifying screens were extremely slow compared with direct-exposure "E" and "D" speed films. Therefore, they should not be used for intraoral radiography because they needlessly expose the patient to excessive X-ray radiation. The direct-exposure films Hanshin Hi-Fi and Hanshin New Silver were equivalent in speed, higher in contrast, and narrower in latitude than Kodak Ektaspeed film. In general, the indirect-exposure films had lower speed, lower contrast and wider latitude than the direct-exposure films. Their speed and contrast would have been increased if intensifying screens had been used. Therefore, indirect-exposure films without intensifying screens should not be used for intraoral radiography.

Radiation Dosage↗
PubMed2001

[New film for intraoral radiography].

Recently, a new film for intraoral radiography was introduced, the Kodak Insight Dental film. The manufacturer claims that this film requires a reduced exposure time compared to Ektaspeed Plus-film, whereas other relevant film characteristics remained unchanged. These claims were investigated in this study. The exposure time of the Insight-film was on average 17% less than that of Ektaspeed Plus-film upon standard manual development, and 49% less than that of Kodak Ultraspeed-film. Compared to the E-speed film, the Insight-film has an identical gradient and spatial resolution (> 10 lp/mm). Compared to the D-speed film the gradient was larger, indicating a better contrast, whereas the resolution was the same. It was concluded that the Insight Dental film can be used in intraoral radiographic diagnosis.

Humans↗
PubMed1999

In vitro degradation of thin poly(DL-lactic-co-glycolic acid) films.

This study was designed to investigate the in vitro degradation of thin poly(DL-lactic-co-glycolic acid) (PLGA) films for applications in retinal pigment epithelium transplantation and guided tissue regeneration. PLGA films of copolymer ratios of 75:25 and 50:50 were manufactured with thickness levels of 10 microm (thin) and 100 microm (thick). Degradation of the films occurred during sample processing, and thin films with a higher surface area to volume ratio degraded faster. Sample weight loss, molecular weight loss, dimensional, and morphological changes were analyzed over a 10-week period of degradation in 0.2 M of phosphate-buffered saline (PBS), pH 7.4, at 37 degrees C. All PLGA films degraded by heterogeneous bulk degradation. Sample weights remained relatively constant for the first several weeks and then decreased dramatically. The molecular weights of PLGA films decreased immediately upon placement in PBS and continued to decrease throughout the time course. PLGA 50:50 films degraded faster than 75:25 films due to their higher content of hydrophilic glycolic units. The results also demonstrated that thick films degrade faster than corresponding thin films with the same composition. This was attributed to the greater extent of the autocatalytic effect, which further was confirmed by heterogeneous gel permeation chromatograms. These studies suggest that the degradation rate of thin films can be engineered by varying film thicknesses.

Biocompatible Materials↗
PubMed2002

Influence of cosolvents and in situ forming hydroxyapatite on the mechanical characteristics of collagen films.

Collagen was processed into films in mixtures containing various ratios of water, propylene glycol, and ethanol. An experimental mixture design was applied to characterize the effects of individual solvents and their interactions on the mechanical properties of collagen films. Scanning electron microscopy (SEM) was used to examine the surface properties of collagen films. The ultimate tensile strength (UTS) and related characteristics of collagen films were also evaluated with dynamic mechanical analysis. The effect of in situ forming hydroxyapatite (HAP) within collagen films at a concentration of 10 mM on the physical characteristics of these films was evaluated by the same methods. With X-ray and SEM examinations, it was confirmed that HAP was formed inside the collagen film. However, the UTS of collagen films without HAP was 4-5 times higher than that with HAP. This was probably due to the discontinuity of the film structure caused by HAP in the collagen films. The results of a statistical analysis of the experimental design revealed the influence of the solvent mixtures on the mechanical properties of the collagen films with and without HAP, showing similar responses for the UTS and modulus of elasticity. Both parameters showed a maximal response in the solvent range containing a lower percentage of ethanol with the desired percentage of propylene glycol to plasticize the collagen films.

Biocompatible Materials↗
PubMed1994

Blood compatibility of sputter-deposited alumina films.

The surface modification of metals by the application of blood compatible ceramics is one approach to developing durable and blood-compatible materials. The blood compatibility of sputter-deposited alumina films was investigated in vitro. The alumina films were prepared by reactive sputtering and conventional sputtering. Diffractometer studies of the alumina films indicate that the sputter-deposited alumina films have amorphous structures. Electron spectroscopy chemical analysis studies of the alumina films indicate that the sputter-deposited alumina films are nonstoichiometric (O/A1 ratio of 1.15-1.66). We examined the platelet reaction to the alumina films and the intrinsic coagulation factor XII activation by the alumina films. Medical grade segmented polyurethane was also tested. The alumina films experienced an adhesion of about 50% fewer platelets than the segmented polyurethane. Also, fewer platelet morphologic changes were observed on the alumina films than on the segmented polyurethane. Factor XII activation was less on the alumina films than on the segmented polyurethane. Surface modification by the sputter-deposited alumina films is promising for developing blood-compatible and durable materials.

Aluminum Oxide↗
PubMed2005

Sol-gel-modified titanium with hydroxyapatite thin films and effect on osteoblast-like cell responses.

Titanium (Ti) surface was coated with hydroxyapatite (HA) films via the sol-gel method. The coating properties, such as crystallinity and surface roughness, were controlled and their effects on the osteoblast-like cell responses were investigated. The film crystallinity was controlled with different heat treatment temperatures (400, 500, and 600 degrees C): Also the surface roughness was changed by using different heating rates (1 and 50 degrees C/min). The obtained sol-gel films had a dense and homogeneous structure with a thickness about 1 mum. The film heat-treated at higher temperature had enhanced crystallinity (600>500>>400 degrees C), while retaining similar surface roughness. When heat-treated rapidly (50 degrees C/min), the film became quite rough, with roughness parameters being much higher (4-6 times) than that obtained at a low heating rate (1 degrees C/min). The dissolution rate of the film decreased with increasing crystallinity (400>>500>600 degrees C), and the rougher film had slightly higher dissolution rate. The attachment, proliferation, and differentiation behaviors of human osteosarcoma HOS TE85 cells were affected by the properties of the films. On the films with higher crystallinity (heat treated over 500 degrees C), the cells attached and proliferated well and expressed alkaline phosphatase (ALP) and osteocalcin (OC) to a higher degree as compared to the poorly crystallized film (heat treated at 400 degrees C). On the rough film, the cell attachment was enhanced, but the ALP and OC expression levels were similar as compared to the smooth films.

Cell Line↗
PubMed2002

Starch acetate--a novel film-forming polymer for pharmaceutical coatings.

Starch acetates (SA) have been investigated as novel, multifunctional excipients for the direct compression tableting process. In this study, the film-forming ability of SA (DS 2.8) and the effect of commonly used plasticizers on the physical properties of SA films were evaluated. The results were compared with the properties of ethylcellulose (EC). Free films were prepared by a solvent-cast method. Mechanical studies, water vapor and drug permeability tests, and thermal analysis (DSC) were used to characterize the film-forming ability of SA and efficiency of tested plasticizers. SA films were tougher and stronger than EC films at the same plasticizer concentration. Also, in most cases, the water vapor permeability of SA films was lower than that of EC films. DSC thermograms supported the findings of the tensile test: plasticizers with several small ester groups (e.g., triacetin and triethyl citrate) were the most compatible with SA. Due to the good mechanical properties, low water vapor, and drug permeabilities of the films, SA seems to be a promising film-former for pharmaceutical coatings. The toughness of SA films may result from their dense film structure, which is due to strong interaction forces between adjacent SA molecular chains.

Permeability↗
PubMed2003

Preliminary biocompatibility experiment of polymer films for laser-assisted tissue welding.

BACKGROUND AND OBJECTIVES: The purpose of this study was to examine the impact of a polymer film for liquid solder strength reinforcement on the short term healing of a wound closed by laser-tissue soldering. MATERIALS AND METHODS: Full thickness incisions created on the dorsum of Sprague-Dawley rats were closed by laser-tissue soldering: albumin solder with Indocyanine Green (ICG) dye was inserted between the incision edges and photothermally coagulated with a diode laser. A poly(DL-lactic-co-glycolic acid) (PLGA) polymer film was implanted subcutaneously in the bottom of the incision (controls had no film). Specimens were harvested at 0, 3, 7, and 14 days for breaking strength testing and histological analysis. RESULTS: Breaking strengths of the controls at 0 and 14 days were statistically stronger than the specimens with the implanted films (t-test, P < 0.05). A slight difficulty in apposing the wound edges due to the film presence may have contributed to the low acute strengths. Interference with the wound contraction process by the films possibly contributed to the lower breaking strength at 14 days. Wound histology indicated a mild foreign body reaction to the polymer film material. CONCLUSIONS: The polymer film was well tolerated by the tissue, and the tissue response to the material was consistent with that seen in the literature. The breaking strength differences between control and film-implanted specimens at 0 and 14 days were probably the result of mechanical complications (tissue apposition and wound contraction) due to the presence of the film, and not due to the film material itself. The use of polymer film patches for liquid solder reinforcement and breaking strength enhancement may have certain application specific issues that need to be addressed. Strategies to account for these issues require further research.

Animals↗
PubMed1997

Stability Factors of Foam Film in Contrast to Fluctuation Induced by Humidity Reduction

We have examined the relationship between dynamic surface properties of aqueous SDS solutions and foam film stability by observing the dynamic surface tension (gammat ), elongation of the lamellae (L lamellae ), and the thickness of the lamellae measured by FT-IR. Three foam film models were used by controlling such factors as the Marangoni effect by changing the SDS concentration, the disjoining pressure with the addition of electrolytes, and the surface viscosity with the addition of glycerin. In order to obtain information about the most effective factor in foam film stability, the lifetime of these films was measured under the circumstances of low relative humidity, at which vigorous fluctuation occured in the foam film. Foam film stability was found to be remarkably enhanced by the Marangoni effect and surface shear viscosity in a thin aqueous film at a relative humidity between 60 and 75%. Under these conditions, mild fluctuation would occur in the films. On the other hand, foam film stability was found to be maintained by the disjoining pressure in a thin aqueous film at the humidity below 60%. Under these conditions, vigorous fluctuation would occur in the foam film. It is concluded that foam film stability of an ionic surfactant solution mainly depends on the disjoining pressure which generates a repulsion force between the two surfaces in contrast to the vigorous fluctuation induced by humidity reduction.

Journal Article↗