Biomedical subjects

E M Hussein

Publications and source records attributed to E M Hussein.

7 recordsLinked to original sources

PubMed1999

Algorithms for density and composition-discrimination imaging for fourth-generation CT systems.

This paper shows that if the off-beam idle detectors in the detection ring of a fourth-generation x-ray computed tomography (CT) system are used to measure the scattered radiation, it is numerically feasible to reconstruct electron-density images to supplement the conventional attenuation-coefficient images of transmitted radiation. It is also shown that by combining these two images, composition changes can be detected with the aid of an effective-atomic-number indicator. The required image-reconstruction algorithms are developed and tested against Monte Carlo simulated measurements, for a variety of phantom configurations. In spite of the relatively poor statistical quality of scattering measurements, it is demonstrated that electron-density images of reasonable quality can be obtained. In addition, it is shown that composition discrimination is possible for materials of effective atomic number greater than five, in the photon energy range of a typical medical x-ray CT system operating at 102 kVp. The obtained supplementary electron-density and composition images can be useful in radiotherapy planning and for studying tumour histology, as well as in industrial and security applications where identification of materials based on density and composition is important.

Algorithms↗

PubMed1997

Skin dose from radionuclide contamination on clothing.

Skin dose due to radionuclide contamination on clothing is calculated by Monte Carlo simulation of electron and photon radiation transport. Contamination due to a hot particle on some selected clothing geometries of cotton garment is simulated. The effect of backscattering in the surrounding air is taken into account. For each combination of source-clothing geometry, the dose distribution function in the skin, including the dose at tissue depths of 7 mg cm(-2) and 1,000 mg cm(-2), is calculated by simulating monoenergetic photon and electron sources. Skin dose due to contamination by a radionuclide is then determined by proper weighting of the monoenergetic dose distribution functions. The results are compared with the VARSKIN point-kernel code for some radionuclides, indicating that the latter code tends to underestimate the dose for gamma and high energy beta sources while it overestimates skin dose for low energy beta sources.

Beta Particles↗

PubMed1994

Radioactivity of phosphate ore, superphosphate, and phosphogypsum in Abu-Zaabal phosphate plant, Egypt.

A measurement of the radioactivity content of phosphate ore material, phosphatic fertilizer (superphosphate), and by-product phosphogypsum in the Abu-Zaabal phosphate plant, Egypt, has been carried out. According to the results of gamma-ray spectroscopy analysis, 238U was found in concentrations of 523, 473, and 134 Bq kg-1; 226Ra in concentrations of 514, 301, and 411 Bq kg-1; 232Th in concentrations of 37, 24, and 19 Bq kg-1; and 40K in concentrations of 19, 3, and 16 Bq kg-1 for the analyzed materials, respectively. The data are discussed and compared with those given in the literature for some other countries in light of permissible radiation dose rates.

Egypt↗

PubMed1994

Determination of beam orientation in radiotherapy planning.

A computer-assisted method for selecting beam orientation in a one-step procedure is presented. Inverse and adjoint techniques are developed to obtain the best beam directions. Both methods rely on determining the "path of least resistance" to radiation from the tumor location to the surface of the section. The effectiveness of beam directions is then determined by monitoring the dose distribution along the section boundary. The inverse and adjoint calculations are performed for three tumor cases using a two-dimensional discrete ordinates transport code. The proposed treatment plans from these calculations are verified against typical treatment plans. The new techniques improved the dose distribution in the treated section. The inverse calculations are useful in sections involving low-density tissues. The adjoint technique can effectively deal with multiple target volumes and/or sections with complex geometry. The proposed method is potentially useful in selecting beam orientations for three-dimensional planning systems and in determining beam intensities in rotational and conformal therapy.

Humans↗

PubMed1984

Oxypertine in tardive dyskinesia: an 8-week controlled study.

In a double-blind placebo controlled trial of oxypertine in the treatment of tardive dyskinesia, 33 patients with chronic schizophrenia received either oxypertine or placebo. At the end of eight weeks, the results showed that oxypertine was superior to placebo at a statistically significant level.

Adult↗

PubMedDate not supplied

Landmine detection: the problem and the challenge.

This paper explores the role of radiation methods in addressing the problem of detecting landmines. The application of neutron activation analysis, with an isotopic source or a pulsed neutron generator, is discussed. The use of neutron moderation as an indicator of the presence of a landmine is also explored. In addition, information provided by measuring scattered photons (gamma- and X-rays) is examined.

Animals↗

PubMedDate not supplied

Optimal design of radiation compensators.

A method to achieve the optimal design of radiation therapy compensating filters in multibeam situations is proposed. Dose distribution is optimized such that it approaches the prescribed value in the target zone, is minimized everywhere else, and does not exceed designated limits at vulnerable regions. Field shapes, sizes, and weights, together with filter thicknesses that take into account missing tissues and body heterogeneities, are calculated as a result of this process. The dose distribution, after the application of the calculated filters and beams, is also predicted. The method is rigorous, and its accuracy depends only upon the accuracy of the applied dose calculation method. Examples are discussed and verified using data obtained from Theraplan 300L treatment planning system.

Equipment Design↗