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[en] The trimesic acid dosemeter is highly sensitive to ionizing radiation. Irradiated trimesic acid fluoresces in response to 455 nm (the excitation wave length being 355 nm). Absorbed doses beginning with 0.02 Gy were detectable by measuring fluorescence intensity. The variation coefficient of measured data was ± 1.77 per cent, following exposure of trimesic acid to 1.5 Gy. With dose rates above 2.5 Gy/min, radiochemical yields were identical for 60Co gamma, pulsed 9 and 15 MV, decelerated, and pulsed electron radiation at mean energy levels between 1.6 and 16.10 MeV. Radiochemical yield was in linear correlation with the absorbed dose. The trimesic acid dosemeter depends only slightly on temperature. It can be stored for several months without any problems. Fluorescence intensity of the exposed solution was found to decline by 0.6 per cent daily. Thus all the properties result in a broad field of application. (author)
Journal
[en] The intention of the study was to demonstrate that a chemical dosimeter on the basis of fluorescing acids is able to measure more sensitively than the Fricke dosimeter. As detectors for ionizing radiation pyromellitic acid (1, 2, 4, 5-benzenetetracarboxylic acid) and trimellitic acid (1, 2, 4-benzenetricarboxylic acid) were investigated. Both solutions were exposed to pulsed 10 MV photons. The dose rate and the radiation dose were modified according to the different questions. The correlation between absorbed dose and intensity of fluorescence was studied from 2 Gy up to doses of 16 Gy. Within this dose range the intensity of fluorescence of the mentioned solutions correlate with the absorbed doses in a single-valued and linear way. The fluorescence of pyromellitic acid is independent of the dose rate in the studied range from 0.6 Gy/min to 5 Gy/min. Detectors with trimellitic acid are able to quantify the absorbed energy of ionising radiation independent of the dose rate from 0.6 Gy/min on, but in contrast to pyromellitic acid only up to 3.8 Gy/min. The stability of the excitation and fluorescence spectra, the fading of the irradiated detectors, the reproducibility of the measured results and the increase of the null value of both solutions qualify for the use of these dosimeters in the clinical routine. (orig./MG)
[de]
Die Untersuchungen erfolgten unter der Zielstellung, ein chemisches Fluessigkeitsdosimeter zu praesentieren, mit dem wesentlich empfindlicher als mit dem Fricke-Dosimeter gemessen werden kann. Die Detektoren bestehen aus Pyromelliticsaeure (1, 2, 4, 5-Benzenetetracarbonsaeure) und Trimelliticsaeure (1, 2, 4-Benzenetricarbonsaeure). Beide Loesungen wurden mit gepulster 10-MV-Bremsstrahlung exponiert, wobei Dosisleistungen und Expositionsdosen entsprechend der Fragestellung variable Parameter waren. Innerhalb des untersuchten Dosisbereiches zwischen 2,0 Gy und 16,0 Gy korrelieren die Fluoreszenzintensitaeten beider Substanzen eindeutig und linear mit den absorbierten Energiedosen. Bei Pyromelliticsaeure verursache eine Variation der Expositionsdosisleistung zwischen 0,6 Gy/min und 5,0 Gy/min keine Aenderung der strahlenchemischen Ausbeute. Der Detektor arbeitet im untersuchten Bereich dosisleistungsunabhaengig. Mit Trimelliticsaeuredetektoren kann man wie mit Pyromelliticsaeuredetektoren mindestens ab 0,6 Gy/min, jedoch im Gegensatz zu diesem Detektor lediglich bis 3,8 Gy/min, dosisleistungsunabhaengig absorbierte Energie ionisierender Strahlung quantifizieren. Die Stabilitaet der Anregungs-und Fluoreszenzspektren, das Fading der bestrahlten Detektoren, die Reproduzierbarkeit der Messergebnisse und die nur geringfuegige Zunahme der Leerwerte beider Loesungen entsprechen Voraussetzungen, die einen Einsatz in der klinischen Routine ermoeglichen. (orig./MG)Journal
No abstract available
Journal
Radiobiologia Radiotherapia; ISSN 0033-8184; 
; v. 26(2); p. 164
; v. 26(2); p. 164
No abstract available
Journal
Radiobiologia Radiotherapia; ISSN 0033-8184; ; v. 26(2); p. 164
; v. 26(2); p. 164
[en] In 1981 the linear accelerator 'Neptun 10 p' will be mounted at the Radiological Clinic of the University of Greifswald. Its place will be an irradiation room which is equipped for a radiation of 1.33 MeV. The strengthening of walls and celling, which is necessary for 9 MeV bremsstrahlung and 10 MeV electron radiation, can only be realized by a self-supporting lead-steel construction for reasons of the distance to the neighbouring house and of the connected conditions of foundation as well as of the load capacity of the existing construction of the roof. As in the eighties similar problems are to be expected in other radiological hospitals of the GDR the constructive solution of the Greifswald linear accelerator project and connected problems of the radiation protection are represented. (author)
Journal
Radiobiologia Radiotherapia; ISSN 0033-8184; ; v. 22(4); p. 460-464
; v. 22(4); p. 460-464
[en] The effect of whole-body irradiation (6.0 Gy) on the development of low-dose streptozotocin diabetes in male C57 Bl/KsJ-mice was investigated. After induction of the process of diabetes development, irradiation failed to interfere with the development of hyperglycemia and did not modify the reduced pancreatic insulin content after exogenous diabetes induction. (author)
Journal
Acta Biologica et Medica Germanica; ISSN 0001-5318; ; v. 41(12); p. 1191-1197
; v. 41(12); p. 1191-1197
[en] In vitro irradiation of rat pancreatic islets up to a dose of 2.5 Gy did neither alter glucose- nor isobutylmethyl xanthine (IBMX)-induced insulin secretion. Insulin as well as glucagon content of irradiated islets corresponded to that of the control tissue. So it was in islets irradiated with 25 Gy which were characterized by a decreased insulin secretion in the presence of glucose and IBMX, respectively. There was no indication of an enhanced hormone output in the radiation medium and it is to be suggested that higher radiation doses affect the insulin release of pancreatic islets in vitro. This must be taken into consideration for radioimmunosuppression experiments. (author)
Journal
Exp. Clin. Endocrinol; ISSN 0013-7251; ; v. 81(1); p. 94-97
; v. 81(1); p. 94-97
[en] Hybridoma cells injected intraperitoneally into mice induce formation of ascites tumors producing ascites fluid with high levels of monoclonal antibodies. Several parameters affect the growth of the immunoglobulin-producing tumors in vivo. In 10 different hybridomas the average ascites tumor formation rate could be increased from 32% (n = 338 mice) to 77% (n = 112 mice) by only one whole-body irradiation of paraffin-pretreated Balb/c mice. Production of monoclonal antibodies was better in males because of the significantly (p < 0.01) increased volume of ascites fluid. From the increased tumor formation rate in irradiated mice it is suggested that in non-irradiated recipients the tumor growth rate was lowered by immunological reactions against hybridoma cells provoked by cell surface neoantigens revealed by cell fusion and/or tumor-associated antigens of the myeloma parent cells as well as by altered antigen pattern caused by possible mutations in the myeloma cell line and/or Balb/c/K strain. (author)
Journal
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