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E El-Khatib

Publications and source records attributed to E El-Khatib.

5 recordsLinked to original sources
PubMed1997

Clinical use of asymmetric collimators.

PURPOSE: To illustrate some of the radiation treatment techniques with asymmetric collimators in one field dimension. METHODS AND MATERIALS: Treatment planning for various sites is done with an in-house developed treatment planning system. Dose distributions in the central plane are illustrated. RESULTS: The use of asymmetric collimation, in addition to being a replacement for cerrobend and lead blocks, can facilitate treatment setup with boost fields and with half-beam asymmetric fields as in matching two adjacent fields, in avoiding nearby critical organ or tissue, and in tangential breast treatment. The use of asymmetric collimators would alter the dose distribution across the radiation field and should be accounted for during treatment planning. In conjunction with arc rotation or multiple asymmetric fields, two-dimensional conformal radiotherapy is possible. CONCLUSION: The full potential of asymmetric collimation requires the use of a proper treatment planning algorithm. Some of the treatment techniques with asymmetric collimation in one field dimension are shown here.

Breast Neoplasms↗
PubMed1983

The density of mouse lung in vivo following X irradiation.

The lungs of mice were irradiated with single X radiation doses of 5 to 14 Gy. Six weeks after irradiation, computed tomographic (CT) scans of the mice were performed at two-week intervals. Beyond 14 weeks after irradiation, the animals were scanned at 1-week intervals. The mice irradiated to 5 and 7 Gy exhibited no change in lung density, in comparison with the unirradiated lungs of control mice up to times of 48 weeks. The mice irradiated to doses of greater than 10 Gy exhibited marked increases in lung density at 15 weeks after irradiation. Increases in density followed a similar time course for these doses, but the magnitude of the density increase was dependent on the radiation dose. An interpretation of these findings in terms of radiation pneumonitis is presented, and the possibility of using CT to monitor lung density in radiotherapy patients is discussed.

Absorptiometry, Photon↗
PubMed1979

[Ultrastructural cytochemistry of the mouse juxtaglomerular apparatus (author's transl)].

The ultrastructural cytochemistry of the mouse juxtaglomerular apparatus has been studied. The specific granules of the juxtaglomerular cells were found to be argentaphobic when ultrathin sections of araldite-embedded renal cortex were stained according to the periodic acid-thio-carbohydrazide-silver proteinate technique of Thiery. This technique revealed an abundant glycogen of type beta in the specific granules and in the cytosol of these cells. The rim of specific granules was positive when ultrathin sections of glutaraldehyde-fixed, glycol methacrylate-embedded kidneys were stained with phosphotungstic-hydrochloric acids at a low pH. A reaction was also shown by the cell coat, lysosomes, autophagolysosomes, residual bodies and part of the Golgi complex. These results indicate that the specific granules of the mouse juxtaglomerular apparatus contains glycoproteins that are glycosylated in the Golgi complex.

Animals↗
PubMedDate not supplied

Improved lung dose calculation using tissue-maximum ratios in the Batho correction.

We have reexamined the Batho power law for computing the dose within and beyond lung irradiated with small and large fields of cobalt-60 and 6-MV x rays. Using slab phantoms consisting of two materials, agreement between calculated and measured doses was within 2% inside lung for 6-MV x irradiation, but much poorer (9%) for cobalt-60 irradiation. For cobalt-60 irradiation, tissue-air ratios (TARs) were used initially in the Batho equation, while for 6-MV x rays, tissue-maximum ratios (TMRs) were used. When we substituted TMR values instead of TAR values for cobalt-60, we found marked improvement by nearly 5% in the accuracy of dose calculated within lung. This was confirmed by numerical comparison of the Batho expression with an analytic solution of the primary and first-scattered radiation. We therefore encourage the use of TMRs for cobalt-60 radiation, especially for larger radiation fields, and provide measured data tables for field sizes up to 50 X 50 cm2, and depths up to 30 cm. In addition to unifying the dosimetry for all megavoltage irradiation, this approach improves the accuracy of doses calculated within lung.

Cobalt Radioisotopes↗