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Biomedical subjects

A Rubach

Publications and source records attributed to A Rubach.

7 recordsLinked to original sources
PubMed2005

The Schwarzschild effect of the dosimetry film Kodak EDR 2.

The magnitude of the Schwarzschild effect or failure of the reciprocity law has been experimentally investigated for the dosimetry film EDR 2 from Kodak. When the dose rate applied to achieve a given dose was reduced by a factor of 12, the net optical density was reduced by up to 5%. The clinical importance of this effect is negligible as long as the films are calibrated at a value of the dose rate approximately representative of the dose rates occurring in the target volume, but in target regions of strongly reduced dose rate the Schwarzschild effect should be allowed for by a correction of the net optical density.

Calibration↗
PubMed1993

Body acupuncture: effect on colonic function in chronic constipation.

Acupuncture has been claimed to be an efficacious treatment for chronic constipation, though there are no studies to prove this. We therefore investigated the effect of body acupuncture on stool frequency and colonic transit time of radiopaque markers in 8 constipated patients (58 +/- 6 years, 3 female; vigorous straining necessary to open bowels without the use of laxatives for more than one year, total colonic marker transit > 60 h) in a control period and during a three weeks treatment period with six sessions. Acupuncture was performed as body acupuncture with electric needles (10 Hz, current titrated to individual threshold, 25 min each session) on acupuncture points Di4 [He Gu], Ma25 [Tian Shu], Le3 [Yuan], and B125 [Da Chang Yu]). Two patients dropped out during acupuncture because symptoms of constipation worsened. In the other 6 patients, stool frequencies and colonic transit times were not significantly different during control and acupuncture period (0.38 +/- 0.09 vs. 0.40 +/- 0.14 defecations per day +/- s.e.m., 95% confidence interval for the difference control minus acupuncture [-0.34; 0.30], and 97 +/- 17 vs. 108 +/- 24h, 95% Cl [-50; 27]). Segmental transit times for right and left hemicolon, and rectosigmoid colon did not differ significantly either. In conclusion, acupuncture as performed in this study does not influence objective parameters of colonic function to a clinically relevant degree.

Acupuncture Points↗
PubMed1983

[Reconstruction of fresh and old ligament injuries of the proximal thumb joint].

In fresh ruptures of the collateral ligaments of the proximal thumb joint conservative therapy often fails; therefore these lesions ought to be operated. A reinsertion of the ligaments which at the most part are torn out at their distal end, using the suture described by Lengemann, proved successful in 16 cases. At old ligament lesions we used the palmaris longus tendon as a ligament-substitute. 6 patients operated according to this method were completely painless at the reexamination which took place on an average 8 months after the operation.

Adult↗
PubMed1983

[Effect of satellite supports of different materials on the surface dose in telecobalt therapy].

The surface doses were measured behind shield supports of different materials with a focus-skin distance of 140 cm. The shield supports were at a distance of 40 cm from the skin. The plates were made of lead glass with a thickness of 11.3 mm, window glass with a thickness of 2.6 mm, plexiglas with a thickness of 5 and 10 mm, and perforated plexiglas with a thickness of 6 mm. The greatest contamination of the useful ray with secondary electrons was measured behind the plexiglas plates, the least contamination was measured behind the plate of lead glass. The relative surface dose is increased by at most 18.5% by plates of plexiglas, while the lead glass plate causes an increase of 3.3%.

Cobalt Radioisotopes↗
PubMed1982

Neutron dosimetry with spherical ionisation chambers III. Calculated results for tissue-equivalent chambers.

Values are given of the average energy required to produce an ion pair, Wn, and of the dose conversion factor, r, for tissue-equivalent chambers filled with either tissue-equivalent gas or air, irradiated by neutrons. The model for finite spherical cavities previously presented in part I was used for the calculations, which employed the W values and stopping powers of the charged particles produced in the materials described in part II. Neutron energies ranging from 0.4 to 14 MeV were considered: many of these energies were chosen because of their particularly large or small total cross-sections in order to explore the range of fluctuations of r and Wn. The results are therefore not very suitable for spectral averaging. Cavity sizes ranging from the infinitesimal Bragg-Gray to the infinite cavity were studied. It was found that the changes of r with cavity size and with neutron energy are smaller for the TE-TE chamber than for the TE-air chamber, but for Wn they are about equal; the TE-TE chamber should therefore be considered the ionisation chamber of choice but absolute doses cannot be determined with it to better than +/- 8%.

Computers↗