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W Weidenmaier

Publications and source records attributed to W Weidenmaier.

27 records · Page 2Linked to original sources
PubMed1986

pH-induced modification of BCNU toxicity on glial cells.

A dose-response relationship for the dependence of the cytotoxic activity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) on extracellular pH has been established. The hypothesis, that the integral dose of the rapidly degrading BCNU determines cytotoxicity, has been examined. Human glial cells exhibited lower survival rates for BCNU exposure at pH 6.5 and pH 6.7, compared to pH 7.4. This effect can be explained by the more rapid decay of BCNU at pH 7.4, leading to a lower integral dose. However, the determination of BCNU decay constants for different pH values and calculation of the integral exposure dose reveal that tolerance to BCNU is increased with decreasing pH.

Astrocytoma↗
PubMed1986

Technique and dosimetry of total body irradiations at Ulm.

At the University of Ulm total body irradiation before bone marrow transplantation is given in nine fractions within three days. A total dose of 13 Gy is applied via four fields with 8-MV X-rays. Dose to the lung is limited to 10.5 Gy by means of individually shaped blocks. The homogeneity of dose distributions is improved by the use of compensators for the lower extremities and boli in the head and neck region. Dosimetric data for treatment planning are measured by an ionization chamber and thermoluminescence dosimeters in water and perspex phantoms. In vivo measurements of dose distributions (ionization chamber, TLD) during each fraction allow modifications of compensators and boli in the case of deviations from calculated data.

Air Ionization↗
PubMed1985

[The effect of beam hardening on CT values].

The investigation has shown that the effect of beam hardening and the nature of surrounding structures must not be neglected when carrying out quantitative measurements. This is particularly true in the presence of strongly attenuating, and therefore strongly beam hardening structures such as bone, in regions where there are wide variations in CT values and when using varying kilo-voltages. Within the range of 0 to 200 HU, the effect of beam hardening is less important when compared with other statistical errors.

Calcium Chloride↗
PubMedDate not supplied

Tibial shaft fractures: assessment of fracture healing with computed tomography.

OBJECTIVE: To assess the capability of CT in assessing stability of tibial shaft fractures with planimetry. MATERIALS AND METHODS: Eighteen patients with fracture of the tibial shaft were treated by external fixator. All patients underwent CT 1, 6, 12, and 18 weeks postoperatively to assess the fracture healing. The callus formation and compacta were determined with planimetry. Fractometry, a noninvasive method to measure stability, was used as the gold standard to determine the stability of the fracture. RESULTS: The patients were divided into three groups according to different periods of time for removal of external fixation. Twelve patients with stable fractures showed a steady increase of callus, which was 50% higher after 12 weeks. Three patients with delayed fracture healing demonstrated an increase of callus of > 50% after 18 weeks. Three patients with unstable fractures obtained only callus formation of < 20% after 15-18 weeks. The external fixator was removed and endomedullary nails were used for stabilization. CONCLUSION: The CT data allow quantification of callus and compacta formation and are able to determine the stability of tibial shaft fractures.

Adolescent↗