Scanning Microdensitometer Research Articles

Use of GafChromic film to diagnose laser generated proton beams

A calibration of three types of GafChromic radiochromic film (HS, MD-55, and HD-810) was carried out on the Crocker Nuclear Laboratory's 76 in. cyclotron at UC Davis over doses ranging from 0.001 to 15 kGy. The film was digitized with a scanning microdensitometer with which it was scanned twice with two different filters to increase the film's effective dynamic range. We demonstrate how this calibrated film can be used to measure the spectrum and total energy of a laser generated proton beam. This technique was applied to an experiment on the 10 J, 100 fs Callisto laser at Lawrence Livermore National Laboratory. The resulting proton spectrum was compared to that obtained by simultaneous measurement of Ti nuclear activation; the two methods give the same proton beam slope temperature and agree in number of protons to within 27%.

Control and analysis software for a laser scanning microdensitometer

A PC-based control software and data acquisition system is developed for an existing commercial microdensitometer (Biomed make model No. SL-2D/1D UV/VIS) to facilitate scanning and analysis of X-ray films. The software is developed in Labview, which includes operation of the microdensitometer in 1D and 2D scans and analysis of spatial or spectral data on X-ray films, such as optical density, intensity and wavelength. It provides a user-friendly Graphical User Interface (GUI) to analyse the scanned data and also store the analysed data/image in popular formats like data in Excel and images in jpeg. It has also on-line calibration facility with standard optical density tablets. The control software and data acquisition system is simple, inexpensive and versatile.

A Data Acquisition and Analysis System for On-Line Calibration and Measurements of Optical Density by a Scanning Microdensitometer

A data acquisition and analysis system has been set up for on-line measurements of spatial variation of optical density using a microdensitometer. The entire processing and control of analog and digital signals as well as data analysis and plotting is carried out using a Window 95/98 based software ‘DEPICT’ developed for the purpose. Any possible errors due to variations in the scanning motor speed, intensity of the light source, and the amplifier gain are avoided by adding a shaft encoder, a photo-detector, and an on-line calibration set up. Optical density scans with a spatial accuracy better than 25 micron over large scan lengths are obtained upto an optical density of 2.5. The data acquisition and analysis system is simple, inexpensive, and is easily adaptable to various other instruments.

Age, strain, and semi-chronic hydergine treatment effects on motor activity and neuronal nucleic acid-protein metabolism in male mice

This study was designed to examine the effects of Hydergine (DHET), co-dergocrine mesylate, treatment on motor activity and neuronal nucleoprotein metabolism in several motor areas of the aging rodent brain, specifically the caudate-putamen (CP), the substantia nigra (SN), and the cerebral cortex layer V (CX). Three age groups of two different strains of mice were used which represented two different aging rates: DBA/2 male mice (short lived) and C57BL/6 male mice (long lived). A representative sample of each age group was injected (IP) daily with a single dose of either DHET (1 mg/kg) or vehicle (0.9% saline) solution for one month. Total spontaneous motor activity was measured using a File apparatus to assess the functional ability of the selected brain areas. Histochemical parameters measured included the relative RNA and protein contents from a homogeneous population of neurons within each nuclei. The RNA and protein contents were assessed with a scanning microdensitometer using azure B and Coomassie staining protocols, respectively. The results of this study provide evidence that DHET does have significant effects on neuronal functioning in the motor compartments studied at the behavioral as well as the histochemical level for DBA/2 male mice. The C57BL/6 strain showed parallel, but less significant, changes in the histochemical parameters and no statistical differences in motor activity. In addition, DHET treatment produced no sign of neurotoxicity within any of the brain nuclei in either strain.

Objective assessment of phantom image quality in mammography: a feasibility study.

The need for test objects in mammography quality control programmes to provide an objective measure of image quality pertinent to clinical problems is well documented. However, interobserver variations may be greater than the fluctuations in image quality that the quality control programme is seeking to detect. We have developed a computer algorithm to score a number of features in the Leeds TOR(MAX) mammography phantom. Threshold scoring techniques have been applied in the first instance; scoring schemes which utilize measures such as signal-to-noise ratio and modulation have also been formulated. This fully automatic algorithm has been applied to a set of 10 films which have been digitized at 25 microns resolution using a Joyce-Loebl scanning microdensitometer. The films were chosen retrospectively from quality control test films to demonstrate: (a) a range of optimized imaging systems, and (b) variation from the optimum. The performance of the algorithm has been compared with that of five experienced observers, and has been shown to be as consistent as individual observers, but more consistent than a pool of observers. Problems have been encountered with the detection of small details, indicating that a more sophisticated localization technique is desirable. The computer performs more successfully with the scoring scheme which utilizes the full imaging information available, rather than with the threshold-determined one. However, both the observers and the computer algorithm failed to identify the non-optimum films, suggesting that the sensitivity of the TOR(MAX) test object may not be adequate for modern mammography imaging systems.

High-resolution scanning microdensitometer

A technique has been developed to enhance the resolution of an optical scanning microdensitometer. Phase shifting optics are used to obtain a signal with high resolution, but with a complex structure. This signal is subtracted from a reference signal to produce the equivalent of an isolated, very narrow, bright line. This line is then scanned across the specimen. Improvements in resolution of about a factor of 2, compared to a conventional optical system, have been observed at numerical apertures up to 0.55, without sacrificing either the working distance or the depth of focus.

The Peak Brightness of SN 1937C in IC 4182 and the Hubble Constant: Comments on Pierce & Jacoby [AJ, 110, 2885 (1995)

view Abstract Citations (27) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Peak Brightness of SN 1937C in IC 4182 and the Hubble Constant: Comments on Pierce & Jacoby [AJ, 110, 2885 (1995)] Schaefer, Bradley E. Abstract The peak brightness of SN 1937C in IC 4182 is important as a calibrator of type Ia supernovae absolute magnitudes. Recently, Pierce & Jacoby [AJ, 110,2885 (1995)] have remeasured some original plates with a scanning microdensitometer and have deduced a peak magnitude and decline rate. Unfortunately, a technical error (relating to day/night vision and the appropriate color correction term) has introduced a large and variable systematic error into all their photovisual magnitudes. In addition, their early remeasured photographic magnitudes are -0.25 mag fainter than those measured by all eight independent observers as well as -0.20 mag fainter than the original measurements of the same plates by Baade and Zwicky. Finally, Pierce and Jacoby deduced the peak magnitude with only 13% of the available data. In this paper, I present an improved analysis using the latest magnitude estimates, analysis techniques, and calibrations. I find the peak B magnitude to be 8.71+/-0.16 at JD2428769.7, while the peak V magnitude was 8.75+/-0.10. The decline in the B light curve over the first 15 days after maximum was 1.07+/-0.11 mag. This leads to a Hubble constant of 57+/-4 km s^-1^ Mpc^-1^. Publication: The Astronomical Journal Pub Date: April 1996 DOI: 10.1086/117906 Bibcode: 1996AJ....111.1668S Keywords: SUPERNOVAE: INDIVIDUAL: SN 1937C; DISTANCE SCALE full text sources ADS | data products SIMBAD (2) NED (2)

The Peak Brightness of SN 1895B in NGC 5253 and the Hubble Constant

The light curve of the Type Ia supernova SN 1895B (in NGC 5253) is important because Sandage et al. have measured a distance to the host galaxy by means of Cepheid variables and thus have derived the Hubble constant. However, the last time the supernova plates were measured was in 1923, and the resultant photometry is inconsistent at the 0.8 mag level. In this paper, I report on the results of my remeasurement of the old supernova plates with a scanning microdensitometer. I find B-magnitudes of >11.3 ± 0.3, 8.36 ± 0.07, 8.51 ± 0.06, 8.54 ± 0.05, and 9.34 ± 0.08 on JD 2,413,359, 2,413,383, 2,413,384, 2,413,385, and 2,413,393, respectively. The last plate was a prism plate, for which I present a flux-calibrated spectrum, taken ~15 days after maximum. Even though only loose constraints can be placed on the light curve shape, the firm limit on the peak magnitude (<8.49 ± 0.03) will provide a firm limit on the Hubble constant. The most likely shape is that of the average Type Ia template of Leibundgut et al., for which the best-fit peak B-magnitude is 8.26 ± 0.11. The deduced probability distribution for H0 is peaked at 51 ± 7 km s-1 Mpc-1, with extreme limits of 61 ± 12 and 26 ± 5 km s-1 Mpc-1.

The contrast-detail behaviour of a photostimulable phosphor based computed radiography system

Contrast-detail measurements were performed on a computed radiography imaging system as a function of detector entrance air kerma over the dose range from 0.743 mu Gy (0.085 mR) to 277 mu Gy (31.8 mR). A theoretical model of contrast-detail behaviour for a photostimulable phosphor computed radiography system has been derived, which is based on a modified version of the Rose theory of threshold detection. Included in the model are both system and X-ray quantum noise terms, as well as the response of the eye. The zero-frequency noise power of the computed film images was measured with a double-beam scanning microdensitometer. For a given detector dose, good agreement was found between the predicted and measured data when this measurement of system noise was included in the model. The contrast-detail results obtained for the computed radiography system were also compared with contrast-detail results for an image intensifier-TV based digital imaging system and a conventional film-screen system.

Distinct intracellular lysozyme content in normal granulocytes and monocytes: a quantitative immunoperoxidase and ultrastructural immunogold study.

Using two different immunological methods, we performed a quantitative estimation of lysozyme (LZ) in normal mature granulocytes and monocytes. An immunoperoxidase reaction for LZ in granulocytes and monocytes of 10 healthy donors measured by a scanning microdensitometer as arbitrary units showed a significantly higher LZ content in granulocytes than in monocytes. An ultrastructural immunogold reaction (IGR) for LZ performed on post-embedded thin sections showed a higher number of total gold grains in neutrophilic granulocytes than in monocytes. In monocytic granules we found a high density of gold grains per micron 2, whereas in granulocytic granules lower values were obtained. In granulocytes, LZ was found in both primary myeloperoxidase (MPO)-positive and secondary MPO-negative granules, and in monocytes the granules showed weak MPO reactivity and high LZ content. Granulocytes previously subjected to phagocytosis of bacteria and latex particles showed release of LZ on degranulation inside the phagosome, whereas in monocytes the granules remained outside the phagosome and released LZ without degranulation. Our study demonstrated a significantly higher total LZ content in granulocytes, a higher granular LZ content in monocytes, and release of LZ from intact monocyte granules during phagocytosis.

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)

Application of maximum likelihood analysis to scanning microdensitometer data from X-ray emulsion chambers

The absolute calibration of the method of determination of the energy and spatial parameters of γ-quanta in X-ray emulsion experiments is presented. X-ray films exposed in the calibration experiment PAMIR by π 0→ 2γ decay formed the experimental material. The accuracy of γ-quantum energy determination by the method of one-point measurement is σ( ln E) ≅0.3. The estimation of shower parameters is solved by the method of maximum likelihood using the darkening density matrix measured with a PDS microdensitometer.

Digital mammography—the comparative evaluation of film digitizers

To study the potential of the computer interpretation of digital mammograms it is necessary to use digitized conventional films because at the present time insufficient resolution may be achieved using computed radiography. For example, the automatic detection of very small subtle calcifications requires digitization at 50 μm or smaller with at least 8 bits of grey level (Chan et al, 1987; Dance, 1993). In this paper we present a simple and practical method to evaluate and compare the technical performance of three film digitizers. These all cost about £20 000 and are being assessed as possible methods for obtaining digital mammograms for a national database (Astley, 1993). The digitizers investigated are a drum scanning microdensitometer, a laser scanning densitometer and a CCD camera. According to manufacturers' specifications, each has a high resolution sampling pixel size (50 μm or less) and is capable of digitizing to a grey level of at least 8 bits over the complete range of diffuse optical densities (0–3 or higher) typically found in a mammogram. The digitizers have been compared by measuring the modulation transfer function (MTF), noise and linearity of each system at a pixel resolution of 50 μm with an 8 bit grey scale. Measurement of these properties provides a means of comparison of important parameters such as resolution and dynamic range. Yin et al (1992) have recently presented an evaluation of the imaging properties of a laser film digitizer using a different approach from that described in this paper.

Quantitative cytochemical study of some enzymatic activities in preovulatory bovine oocytes after in vitro maturation

In the present study quantitative cytochemical assays were used to measure some enzymatic activities in situ in bovine meiotically immature oocytes and oocytes matured in vitro, since the special metabolic activity of the growing oocytes may be a pivotal factor in stabilizing the meiotically arrested oocytes. Modifications of this particular metabolism might destabilize the arrested meiosis. Preovulatory oocytes, mostly at the germinal vesicle stage, were obtained by puncturing follicles ranging from 2 to 6 mm in diameter with a hypodermic needle. A group of collected oocytes was incubated in maturation medium CRML 1066 to obtain metaphase II oocytes. Succinate, lactate and glucose-6-phosphate dehydrogenase activities in just collected meiotically immature and in vitro matured oocytes were assayed cytochemically. Microdensitometric measurements were made with a Vickers M85a scanning microdensitometer. Our findings show that: 1) succinate dehydrogenase activity was significantly increased in matured oocytes; 2) lactate dehydrogenase activity was present and very strong in immature oocytes but was detectable in only about 50% of matured oocytes, with significantly lower integrated optical density values; 3) glucose-6-phosphate dehydrogenase activity was very high in immature oocytes but significantly decreased after in vitro maturation; 4) there was no linear correlation between the integrated optical densities of the three enzymatic activities and the diameters of the oocytes. We suggest that the ability to utilize glucose may appear earlier in bovine oocytes than in other species and takes place at the time of maturation.

Kinetic analysis of lactate dehydrogenase in situ in mouse liver determined with a quantitative histochemical technique

The kinetics of lactate dehydrogenase in situ were studied in sections of unfixed liver of the male mouse using a quantitative histochemical technique. The sections were incubated on substrate-containing gel films. The absorbance of the final reaction products deposited in a single hepatocyte was measured continuously during the incubation as a function of incubation time using a scanning microdensitometer. The absorbance increased non-linearly during the first minute of incubation, but linearly for at least the next 3 min afterwards. The initial velocity (vi) of the dehydrogenase was calculated from two equations proposed previously by us, vi = 2.82 degrees A and vi = vi + 2 degrees A, where vi and degrees A are, respectively, the gradient and intercept of the linear regression line of absorbance on time for incubation times between 1 and 3 min. The dependence of vi on lactate concentration gave the following mean kinetic constants. For periportal hepatocytes, the apparent Km = 14 mM and Vmax = 80 mumoles hydrogen equivalents formed cm-3 hepatocyte cytoplasm min-1. For pericentral hepatocytes, Km = 12 mM and Vmax = 87 mumoles hydrogen equivalents cm-3 min-1. The Km values are very similar to those determined previously from biochemical assays. The concentrations of the enzyme in single hepatocytes calculated from the Vmax values are in good agreement with those obtained by another method. These data substantiate the validity of our equations.

Recommissioning of the Sheffield Gamma Knife Unit following a Source Change

Reinstallation of the Sheffield Gamma Knife Unit was completed in early November, 1991, following the replacement of the cobalt sources. Two methods were used to evaluate the isodose configuration within the replenished unit. The first method used a scanning microdensitometer to interrogate films exposed within a spherical phantom, whilst the second relied upon a series of measurements obtained with an array of diodes. The results produced by the latter method compared more favorably with the computer-generated theoretical curves. The two sets of results are presented and some possible explanations for the discrepancies are proposed.

Cytophotometric assay of cytochrome oxidase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase activities in human peroxidized spermatozoa

Human spermatozoa contain appreciable amounts of intracellular glutathione, which has a protective function against peroxidative degradation of spermatozoal polyunsaturated fatty acids by the NADPH-dependent glutathione peroxidase/reductase enzymatic system. The glutathione system provides a basic defense against peroxidative damage, without which the superoxide dismutase system would dominate. Since oxidative damage is said to include enzyme leakage and changes in metabolism, cytochrome oxidase and lactate dehydrogenase activities were used as indicators of the energy metabolism in unwashed and washed human spermatozoa during lipid peroxidation. Lipid peroxidation was induced by aerobic incubation of sperms in the presence of sodium ascorbate and ferrous sulphate. In addition, since NADPH concentrations influence the concentration of reduced glutathione, we studied glucose-6-phosphate dehydrogenase activity as an indicator of pentose phosphate shunt activity, the main source of NADPH. Microdensitometric measurements of the three enzymes were made by a Vickers M85a scanning microdensitometer. We found that the lipid peroxidation process greatly affects the 3 enzymatic activities examined and that seminal plasma protects against the extensive deleterious effects of lipid peroxidation.

X-ray holographic microscopy using photoresists

Gabor x-ray holograms of biological specimens and of test objects that display ≤56–nm resolution are presented. This spatial resolution is more than an order of magnitude smaller than what has been achieved previously in x-ray holography. The holograms were recorded on photoresist using 2.57-nm soft x rays from the X–17t undulator at the National Syncrotron Light Source at Brookhaven National Laboratory. The processed photoresists were enlarged with an electron microscope and digitized using a scanning microdensitometer; the digitized holograms were reconstructed numerically. The exposure requirements were in good agreement with simple theory. The method offers promise as a technique for soft-x-ray microscopy.

DNA measurements in chronic hepatitis, cirrhosis and hepatocellular carcinoma

It has been documented that chronic hepatitis may progress to cirrhosis and then develop hepatocellular carcinoma (HCC). To test whether abnormal cellular DNA increases along this line of development, liver tissues from 48 patients with chronic hepatitis, 17 with cirrhosis, and 8 with HCC were investigated for cellular DNA content with a scanning microdensitometer. Seven of 8 HCCs and 2 cirrhotic livers adjacent to HCC had abnormally increased cellular DNA content. Only 4 livers from patients with chronic liver diseases other than HCC had abnormal cellular DNA content. The cellular DNA content in livers not accompanying HCC was not related to the patient's age, histological diagnosis, and hepatitis inflammatory activity. The results confirmed the increase of cellular DNA content in HCC, but did not provide evidence of a progressively increasing DNA content from chronic hepatitis to liver cirrhosis. However, cirrhotic livers with abnormal hepatocytic DNA content deserve careful follow-up for the early detection of HCC.

Drug‐induced cell cycle perturbation in chemotherapy of patients with non‐small cell lung cancer

To observe in vivo cell cycle perturbation in the chemotherapy of lung cancer, tumour cell kinetics during the first course of chemotherapy were measured in seven patients with histologically-verified non-small cell lung cancer. The tumour cells were aspirated from six lymph nodes and one subcutaneous nodule both prior to treatment and twice weekly after the administration of chemotherapeutic agents. The nuclear DNA content of aspirated tumour cells was measured with a scanning microdensitometer at a wavelength of 550 nm after the modified Feulgen reaction. The cell population in cell cycle was estimated with a cumulated percentage scale. Marked cell cycle perturbation occurred within one week after initiation of chemotherapy. There was a decrease in the G1 cell population, from 70.6 +/- 9.1% to 26.1 +/- 11.4%, and a corresponding increase of cells in G2-M phase, from 21.4 +/- 8.7% to 63.7 +/- 10.0%. The proportion of cells in S phase was slightly increased from 8.0 +/- 1.5% to 10.1 +/- 3.2% during this period. The degree of cell cycle changes was unrelated to the clinical response to chemotherapy.