[en] The potential risk by being exposed by artificial UV-sources at the workplace in Austria was measured and evaluated. A representative overview of the measurement results, the evaluation of the UV-exposure risk and recommendations to reduction of the risk is given. The international organizations ACGIH and ICNIRP have promulgated guidelines on exposure to ultraviolet radiation (UVR), to protect the general public and workers from hazards which result from being exposed to UVR sources. As the two guidelines differ in some definitions of the exposure duration to calculate the radiant exposure, different results may be obtained. Further it is possible to use the concept of minimal erythema doses - MED's in order to analyze the ability of UV radiation to produce erythema in the human skin. The differences have been analyzed by using the ICNIRP and ACGIH guidelines and the concept of MED's. The different results were compared and discussed. Measurements of UV-radiation concerning photobiological hazards were performed with spectral or integral methods. To increase the accuracy of the measurement a wavelength-dependent correction factor for the integral detectors was used. For simplified handling, the correction factors were classified into different spectra, lamp groups respectively. (author)

[en] Phase analysis of radionuclide ventriculograms is used for identifying ischemic wall motion abnormalities. Myocardial segments with an abnormal phase and the synchronicity of LV wall motion can be assessed from a histogram of LV phase distribution. We examined in this study the sensitivity of SDP-LV for identifying coronary artery disease and its specificity in patients with normal and various degrees of left ventricular impairment. A total of 84 patients were studied. In severe left ventricular impairment, phase analysis did not aid in distinguishing coronary artery disease from other causes of ventricular dysfunction. By contrast, phase analysis was highly sensitive and specific for coronary artery disease in patients with normal or moderately depressed left ventricular function

[en] The panel discussion opened with a question concerning whether true quantification of myocardial sympathetic presynaptic function or receptor density can be obtained with currently available radiopharmaceuticals. What are the relative advantages of the two general approaches that have been proposed for quantification: (1) The assessment of tracer distribution volume in tissue following bolus injection and (2) quantification based on tracer displacement kinetics following administration of excess unlabeled tracer. It was pointed out that tracer kinetics for the delineation of presynaptic and postsynaptic binding sites by radiopharmaceuticals or radiolabeled receptor antagonists are rather complex, reflecting several physiologic processes that are difficult to separate. Several approaches were examined. The possibility of regional definition of receptor density by PET was questioned and it was noted that regions of interest can be applied to calculate regional receptor kinetics. However, due to the limited spatial resolution of PET, only average transmural values can be determined. The discussion then turned to the discrepancy between the known sparse parasympathetic innervation of the heart and the high density of muscarinic receptors observed with PET. Experiences with MIBG imaging were reported, including uptake in the transplanted heart and interaction of drugs with MIBG uptake

[en] The kinetics of [1-14C]acetate oxidation in isolated perfused rat hearts have been determined over a range of perfusion conditions. Effluent measurements demonstrated that 14CO2 cleared biexponentially over 50 minutes after bolus injection of [1-14C]acetate into normoxic hearts perfused with 5 mM glucose and 10 mU/ml insulin. The clearance half-time (t1/2) for the predominant initial clearance phase was 3.1 +/- 0.5 minutes (n = 4). MVO2 was varied over a fourfold range by hypoxia and phenylephrine stimulation (t1/2, 7.2 +/- 1.2 and 2.2 +/- 0.2 minutes, respectively) and in the presence of alternate substrates (lactate, 2 mM; DL-3-hydroxybutyrate, 20 mM; and palmitate, 0.1 mM), which did not modify either tricarboxylic acid (TCA) cycle flux or acetate kinetics. A good correlation (r = 0.93) was observed between k, the rate constant for the initial phase of 14CO2 clearance, and TCA cycle flux, estimated from oxygen consumption. In contrast to results with [1-14C]acetate, lactate (2 mM) increased t1/2 for 14CO2 clearance from a bolus injection of [1-14C]palmitate from 3.0 +/- 0.4 minutes (n = 3) at control to 4.3 +/- 0.2 minutes (n = 3, p less than 0.01). Addition of acetate in nontracer amounts (0.5 or 5 mM) caused significant underestimation of TCA cycle flux when estimated with [1-14C]acetate. 14CO2 clearance accounted for 88-98% of total effluent 14C between 10 and 20 minutes after [1-14C]acetate bolus injection; rate constants for clearance of 14CO2 and total 14C clearance were very similar during this period, and these two rate constants did not differ significantly from each other under any conditions tested

[en] The active veto shielding of a low-level gamma spectrometer has been optimized to reduce the background in the interval 20-2700 keV by a factor of nine. The signal to noise ratio was increased, due to the reduction of electromagnetic interference coming from the power line, by using an uninterruptible power supply and specially designed line filters. The overall performance of the veto shielding was improved by using time spectroscopy to find the optimum time duration for the coincidence window

[en] Conventional nuclear medicine procedures such as T1-201 scintigraphy allow only qualitative assessment of regional myocardial blood flow. PET provides attenuation-corrected images of myocardial tracer distribution and thus the potential for quantitative measurement of tracer kinetics. Dynamic PET imaging with high temporal resolution (10 sec/frame) after intravenous injection of the blood flow tracer N-13 ammonia was applied to seven healthy human subjects at rest and after intravenous dipyradamole. A three-compartmental tracer kinetic model was used to fit regional myocardial time-activity curves yielding estimates of blood flow and rate constants for tracer retention. At rest, blood flow averaged 64 +- 10 mL/min/100 g and increased after intravenous application of dipyridamole to 274 +- 84 mL/min/100 G. These PET values agree well with invasively measured coronary blood flow

[en] ACGIH and ICNIRP have promulgated guidelines on exposure to ultraviolet radiation (UVR). In these guidelines two independent exposure limits for UVA (315 nm - 400 nm) and for total UV (180 nm - 400 nm), respectively, are given. The two guidelines differ in the definition of the exposure duration to calculate the UVA radiant exposure, which may lead to different results. In addition to the above guidelines, the concept of minimal erythema doses (MEDs) was adopted. A typical photodermatology workplace has been analysed by using the ICNIRP and ACGIH guidelines as well as the concept of MEDs. The use of MED as an indicative level for possible harmful effects on the skin allows one to account for individual skin types. For the workplace analysed, the ICNIRP limits are exceeded, but the skin exposure is a factor of two below the MED of the nurse (Skin Type III), which might be acceptable if eye protection is worn. (author)

No abstract available

[en] Report of the highlights of the meeting, which were: physics and instrumentation, radiopharmacy, cardiology, neurosciences, oncology, as well as radiotherapy

[en] Ischemically injured reperfused myocardium is characterized by increased 18F-fluorodeoxyglucose uptake as demonstrated by positron emission tomography. To elucidate the metabolic fate of exogenous glucose entering reperfused myocardium, D-[6-14C] glucose and L-[U-13C] lactate were used to determine glucose uptake, glucose oxidation and the contribution of exogenous glucose to lactate production. The pathologic model under investigation consisted of a 3 h balloon occlusion of the left anterior descending coronary artery followed by 24 h of reperfusion in canine myocardium. The extent and severity of myocardial injury after the ischemia and reperfusion were assessed by histochemical evaluation (triphenyltetrazolium chloride and periodic acid-Schiff stains). Thirteen intervention and four control dogs were studied. The glucose uptake in the occluded/reperfused area was significantly enhanced compared with that in control dogs (0.40 +/- 0.14 versus 0.15 +/- 0.10 mumol/ml, respectively). In addition, a significantly greater portion of the glucose extracted immediately entered glycolysis in the intervention group (75%) than in the control dogs (33%). The activity of the nonoxidative glycolytic pathway was markedly increased in the ischemically injured reperfused area, as evidenced by the four times greater lactate release in this area compared with the control value. The dual carbon-labeled isotopes showed that 57% of the exogenous glucose entering glycolysis was being converted to lactate. Exogenous glucose contributed to greater than 90% of the observed lactate production. This finding was confirmed by the histochemical finding of sustained glycogen depletion in the occlusion/reperfusion area. The average area of glycogen depletion (37%) significantly exceeded the average area of necrosis