Comparison of X-ray Fluorescence and Optical Density Methods for Evaluation of Exposures of Dosimetric Films

1978 ◽  
Vol 34 (1) ◽  
pp. 55-59 ◽  
Author(s):  
G. Agelao ◽  
G. Greco ◽  
M. C. Romano ◽  
D. Di Mariano
Keyword(s):  
Optical Density ◽  
X Ray ◽  
Density Methods

scholarly journals Analysis of Sensitometry in Radiographic Films using Optical Density Measurement

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Oladotun A. Ojo ◽  
Peter A. Oluwafisoye ◽  
Charles O. Chime
Keyword(s):  
Quality Control ◽  
Optical Density ◽  
Density Measurement ◽  
Absorbed Dose ◽  
Good Prediction ◽  
Radiographic Film ◽  
X Ray ◽  
Dose Curve ◽  
Optical Density Measurement ◽  
Before And After

The sensitivity of radiographic films is an important factor to the clarity and accuracy of X-ray exposure to patients during treatment or diagnostic periods. It is therefore important to do a thorough analysis of the sensitivity of the radiographic film before and after exposure to enhance the Quality Assurance (QA) and the Quality Control (QC), of the exposure procedures. The optical densities (OD) of each film was measured, with a densitometer model MA 5336, made by GAMMEX. These values were then converted to the absorbed dose (X mGy), which is the amount of dose absorbed by each patient. The optical density versus the dose curve, followed the expected pattern, showing a good prediction from the General model, that the films employed in the exposures were of good quality and standard. Hence the optical density versus dose sensitometric curves depicts the outcome of the various films sensitivity after an exposure to the X-ray radiation through the patients.

scholarly journals The Chemistry of Heteroarylphosphorus Compounds, Part 16.+ An X-Ray Structural Study of (2-Thienyl)bis(2,2′-biphenylylene)phosphorane. A Comparison with Related Methyl and Aryl bis(2,2′-biphenylylene)- spirophosphoranes

1983 ◽  
Vol 38 (4) ◽  
pp. 465-469 ◽  
Author(s):  
David W. Allen ◽  
Lorraine A. March ◽  
Ian W. Nowell ◽  
John C. Tebby
Keyword(s):  
Least Squares ◽  
Electron Density ◽  
Structural Study ◽  
Equatorial Plane ◽  
Title Compound ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Thienyl Group ◽  
Density Methods ◽  
Least Squares Techniques

AbstractCrystals of the title compound are monoclinic, a= 18.9 93 (11), b = 8.757(5), c= 13.267(8) Å, β = 106.60(5)°, Z = 4 in space group Cc (Cs4 , No. 9). The structure was determined by Patterson and electron-density methods and refined by least squares techniques to R= 0.081, R′ = 0.085 for 1293 independent reflections classified as observed. The molecule is found to adopt an almost regular trigonal bipyramidal geometry in which the two biphenylylene units span apical-equatorial positions and the 2-thienyl group occupies the remaining equatorial site. The 2-thienyl group, which is disordered, does not lie in the equatorial plane, and there is no indication of C2pπ → P3dπ-t interactions between the heteroaryl group and phosphorus. The steric requirements of the 2-thienyl group appear to be comparable with those of methyl and phenyl groups in bis(2,2′-biphenylylene)spiro-phosphoranes.

Digital automatic calculator for a meter for measuring the optical density of x-ray pictures

1988 ◽  
Vol 31 (2) ◽  
pp. 135-136
Author(s):  
A. A. Ketkovich ◽  
A. M. Lizunov ◽  
V. S. Fedosov
Keyword(s):  
Optical Density ◽  
X Ray

A First Experimental Electron Density Study on a C70 Fullerene: (C70C2F5)10

2010 ◽  
Vol 65 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roman Kalinowski ◽  
Manuela Weber ◽  
Sergey I. Troyanov ◽  
Carsten Paulmann ◽  
Peter Luger
Keyword(s):  
High Resolution ◽  
Electron Density ◽  
Theoretical Calculations ◽  
Asymmetric Unit ◽  
Data Set ◽  
X Ray ◽  
Atomic Properties ◽  
Density Methods ◽  
Experimental Electron Density ◽  
Density Study

The electron density of the C70 fullerene C70(C2F5)10 was determined from a high-resolution X-ray data set measured with synchrotron radiation (beamline F1 of Hasylab/DESY, Germany) at a temperature of 100 K. With 140 atoms in the asymmetric unit this fullerene belongs to the largest problems examined until now by electron density methods. Using the QTAIM formalism quantitative bond topological and atomic properties have been derived and compared with the results of theoretical calculations on the title compound and on free C70

scholarly journals Comparative Evaluation of the Radiopacity of Bone Graft Materials used in Dentistry

2017 ◽  
Vol 7 (3) ◽  
pp. 150-155 ◽  
Author(s):  
Emine S Kursun-Çakmak ◽  
Nihat Akbulut ◽  
Dogan D Öztas
Keyword(s):  
Statistical Analysis ◽  
Bone Graft ◽  
Bone Tissue ◽  
Optical Density ◽  
Comparative Evaluation ◽  
Statistical Significance ◽  
Radiographic Images ◽  
X Ray ◽  
Materials Used

ABSTRACT Introduction Ample radiopacity in order to distinguish from the surrounding tissues is a desirable property of dental graft materials. A total of 15 bone graft materials’ (BGMs) opacities were analyzed in this study. Materials and methods Graft materials were placed in the implant cavity (5 × 10 mm) in cadaver's mandible respectively. Cavity was exposed by using periapical film and a dental X-ray machine at 70 kVp and 8 mA. The optical density of the radiographic images was measured with a transmission densitometer. One-way analysis of variance (ANOVA) was conducted for statistical analysis. Results Among the materials tested, the most radiolucent bone grafts were Grafton and Allogenix with a statistical significance of p ≥ 0.05. 4Bone and Bego Oss exhibited the highest radiopacity with a statistical significance of p ≥ 0.05. Inadequate radiopacity of the dental graft materials may lead to confusion among clinicians in the radiographical follow-up. Among 15 BGMs tested, only three had higher density than bone tissue. Conclusion The radiopacity of the BGM was found to be higher than bone at only three of them. How to cite this article Kursun-Çakmak ES, Akbulut N, Öztas DD. Comparative Evaluation of the Radiopacity of Bone Graft Materials used in Dentistry. J Contemp Dent 2017;7(3):150-155.

X-ray Structural Study of 5-Phenyl-10,11-dihydrodibenzo[b,f]phosphepin-5-oxide

1980 ◽  
Vol 35 (2) ◽  
pp. 133-135 ◽  
Author(s):  
David W. Allen ◽  
Ian W. Nowell ◽  
Philip E. Walker
Keyword(s):  
Least Squares ◽  
Electron Density ◽  
Structural Study ◽  
Title Compound ◽  
Bond Distance ◽  
Direct Methods ◽  
X Ray ◽  
Phenyl Rings ◽  
Density Methods ◽  
Least Squares Techniques

AbstractCrystals of the title compound are triclinic, a = 8.533(5), b = 11.106(6), c = 8.815(5) Å, a = 107.83(6), β = 104.99(6), γ = 81.30(5)°, Z = 2, space group P1̄. The structure was determined by multisolution direct methods and electron density methods. Refinement by least-squares techniques gave a final R = 0.081 for the 1753 independent reflections. The molecule adopts a butterfly-type conformation such that the fused phenyl rings are inclined to each other at an angle of 56.8°. The P-0 bond distance is 1.506(4) Å; the endocyclic angle at phosphorus is 107.2(3)° and the exocyclic angles vary from 106.5 to 111.9(3)°.

scholarly journals An Innovative Low Cost Bone Densitometer Based on Conventional X-Ray Facility

2013 ◽  
Vol 4 (1) ◽  
pp. 95-100
Author(s):  
Jubaid Abdul Qayyum ◽  
Md Masum Howlader ◽  
Md Tamzeed-Al-Alam ◽  
Md Saiful Islam ◽  
Tahmid Latif ◽  
...  
Keyword(s):  
Optical Density ◽  
Bone Densitometry ◽  
Bone Fractures ◽  
Human Subjects ◽  
Medical Physics ◽  
Low Cost ◽  
X Ray ◽  
Bone Densitometer ◽  
The Third World ◽  
Processing Factors

Osteoporosis or bone loss affects many people, particularly the aged women, and leads to disabling bone fractures. An early diagnosis could provide preventive management. However, available bone densitometry equipment are very expensive and not available widely in the Third World. The present work presents the design & development of an innovative low cost bone densitometer based on conventional X-ray equipment available widely. The main innovation is the incorporation of a stack of aluminium with varying thickness placed beside the limb of a patient while taking an X-ray image. Then the optical density of the bone area in the developed film is compared to that from the aluminium stack, which eliminates variations due to all other processing factors, and gives a measure of the bone density. A low cost device has been developed to measure the optical density of the X-ray film over a circular area of about 1cm to give an average reading, which is more appropriate than spot metering in this application. Preliminary measurements of a few human subjects using this equipment clearly indicate the differences obtained due to expected osteoporosis. Calibration with standard bone densitometry equipment could provide values in standard units. This low cost innovative method and equipment appears to provide a low cost alternative to the diagnosis of osteoporosis. DOI: http://dx.doi.org/10.3329/bjmp.v4i1.14693 Bangladesh Journal of Medical Physics Vol.4 No.1 2011 95-100

First-principles X-ray absorption dose calculation for time-dependent mass and optical density

2018 ◽  
Vol 25 (3) ◽  
pp. 833-847 ◽  
Author(s):  
Viatcheslav Berejnov ◽  
Boris Rubinstein ◽  
Lis G. A. Melo ◽  
Adam P. Hitchcock
Keyword(s):  
Photon Energy ◽  
Optical Density ◽  
Exposure Time ◽  
First Principles ◽  
Dose Calculation ◽  
Time Dependent ◽  
X Ray ◽  
Effective Time ◽  
Time Integral ◽  
X Ray Absorption

A dose integral of time-dependent X-ray absorption under conditions of variable photon energy and changing sample mass is derived from first principles starting with the Beer–Lambert (BL) absorption model. For a given photon energy the BL dose integralD(e, t) reduces to the product of an effective time integralT(t) and a dose rateR(e). Two approximations of the time-dependent optical density,i.e.exponentialA(t) =c+aexp(−bt) for first-order kinetics and hyperbolicA(t) =c+a/(b+t) for second-order kinetics, were considered for BL dose evaluation. For both models three methods of evaluating the effective time integral are considered: analytical integration, approximation by a function, and calculation of the asymptotic behaviour at large times. Data for poly(methyl methacrylate) and perfluorosulfonic acid polymers measured by scanning transmission soft X-ray microscopy were used to test the BL dose calculation. It was found that a previous method to calculate time-dependent dose underestimates the dose in mass loss situations, depending on the applied exposure time. All these methods here show that the BL dose is proportional to the exposure timeD(e, t) ≃K(e)t.

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