Impact of the Frequency and Type of Procedures Performed in Nuclear Medicine Units on the Expected Radiological Hazard.

Nuclear medicine procedures play an important role in medical diagnostics and therapy. They are related to the use of ionizing radiation, which affects the radiological exposure of all of the persons involved in their performance. The goal of the study was to estimate the doses associated with the performance of various nuclear medicine procedures in order to optimize workload management. The analysis was performed for 158 myocardial perfusion scintigraphy procedures, 24 bone scintigraphies, 9 thyroid scintigraphies (6 with use of 131I and 3 with 99mTc), 5 parathyroid glands and 5 renal scintigraphies. In this evaluation, two possible locations of thermoluminescent detectors, used for measurements, were taken into consideration: in the control room and directly next to the patient. It was shown how the radiological exposure varies depending on the performed procedure. For high activity procedures, ambient dose equivalent registered in the control room reached the level over 50% of allowed dose limit. For example, ambient dose equivalent obtained in control room when performing bone scintigraphy only was 1.13 ± 0.3 mSv. It is 68% of calculated dose limit in the examined time span. It has been shown that risk associated with nuclear medicine procedures is influenced not only by the type of procedure, but also by the frequency of their performance and compliance with the ALARA principle. Myocardial perfusion scintigraphy accounted for 79% of all evaluated procedures. The use of radiation shielding reduced the obtained doses from 14.7 ± 2.1 mSv in patient's vicinity to 1.47 ± 0.6 mSv behind the shielding. By comparing the results obtained for procedures and dose limits established by Polish Ministry of Health, it is possible to estimate what should be the optimal division of duties between staff, so that everyone receives similar doses.

The elemental changes occurring in the rat liver after exposure to PEG-coated iron oxide nanoparticles: total reflection x-ray fluorescence (TXRF) spectroscopy study.

The main goal of this study was to evaluate in vivo effects of low dose of PEG-coated magnetic iron oxide nanoparticles (IONPs) on the rat liver. The IONPs was intravenously injected into rats at a dose equaled to 0.03 mg of Fe per 1 kg of an animal body weight. The elemental composition of liver tissue in rats subjected to IONPs action and controls were compared. Moreover, in order to determine the dynamics of nanoparticles (NPs) induced elemental changes, the tissues taken from animals 2 hours, 24 hours, and 7 days from IONPs injection were examined. The analysis of subtle elemental anomalies occurring as a result of IONPs action required application of highly sensitive analytical method. The total reflection X-ray fluorescence spectroscopy perfectly meets such requirements and therefore it was used in this study. The obtained results showed increasing trend of Fe level within liver occurring 2 hours from IONPs injection. One day after NPs administration, the liver Fe content presented the baseline level what suggests only the short-term accumulation of nanoparticles in the organ. The Ca, Cu, and Zn levels changed significantly as a result of NPs action. Moreover, the anomalies in their accumulation were still observed 7 days after IONPs injection. The level of Cu decreased while those of Ca and Zn increased in the liver of NPs-treated animals. The reduced liver Cu, followed by elevated serum level of this element, might be related in triggering the mechanisms responsible for Fe metabolism in the organism.

THE INFLUENCE OF PRE- AND POST-IRRADIATION ANNEALING ON LiF:Mg,Cu,P STABILITY.

The influence of pre- and post-irradiation annealing procedures on LiF:Mg,Cu,P (trade name MCP-N) thermoluminescent detector stability was investigated. The detectors were processed in four groups, undergoing complete or incomplete preparation cycles (containing pre- and/or post-irradiation annealing in various combinations). Each cycle was repeated 10 times. The decrease in the stability was observed in groups with pre-irradiation annealing procedure, and not observed in other groups that were found to be apparently stable. The influence of the thermal history on the properties of the detectors was also investigated by swapping the chosen groups of detectors with respect to the annealing cycles. Changes in the properties of the detectors were observed after next 10 cycles of measurements too. Exponential model was proposed to describe the trends observed at two parts of the experiment. Its application for the dose corrections related to the cycle number of the readout improves the accuracy of final dose determination.

Evaluation of spatial and seasonal radioactivity dose fluctuations in a Wierzchowska Górna limestone cave.

Measurements of the dose rate changes were carried out in order to assess seasonal and spatial radioactivity variations in the largest limestone cave of the Polish Jura Wierzchowska Górna. Thermoluminescence detectors, which were annealed, calibrated and protected against humidity were used. Measurements were repeated four times in 13 locations to observe possible changes. The external dose rate was in the range of 0.004-0.106 mGy/quarter. The results were influenced by the detector locations - lower doses were estimated closer to the cave entrance and the highest doses were in the so-called 'primitive man room'. Doses measured in four periods were statistically significantly different. The external dose level as well as seasonal and spatial dose changes measured in the cave were low. In other caves where external doses are higher, seasonal and spatial dose changes may have a stronger impact on radiological hazard.

Relationship between kinetics of albumin-bound bilirubin and water-soluble urea in extracorporeal blood purification.

BACKGROUND: The purpose of the study was to examine the relationship between urea and conjugated bilirubin kinetics during extracorporeal liver support (ELS) therapy and to determine the dose of therapy for urea and conjugated bilirubin as markers for water-soluble and protein-bound solutes, respectively. METHODS: Kinetics of urea and bilirubin were described by standard two-compartment models with central clearance, constant intercompartment clearance, constant generation rate and constant volume. While the concentration of urea was assumed as equilibrated between compartments at the beginning of ELS therapy, the concentration of conjugated bilirubin between compartments was assumed to follow the partition of albumin between plasma and interstitial spaces. Treatment dose was calculated as removed solute mass and fractional solute removal. RESULTS: Seven patients were studied during 15 treatments lasting at least 6 h. Bilirubin distribution volume of 14.8 ± 5.4 L was not different from urea extracellular water volume of 15.0 ± 2.8 L. The correspondence between models was used to predict the mass of bilirubin removed based on extracellular volume obtained from urea kinetics, average data from bilirubin kinetics, as well as selected treatment and patient information. The prediction of bilirubin mass removed based on this reduced information was not different from the mass of solute removed based on complete bilirubin kinetic analysis. CONCLUSIONS: The correspondence between kinetics of urea and conjugated bilirubin can be used to identify the bilirubin distribution volume from urea kinetic analysis. This information is then useful to estimate and predict the solute removal of conjugated bilirubin in ELS.

Removal of bile acids by two different extracorporeal liver support systems in acute-on-chronic liver failure.

Acute-on-chronic liver failure (ACLF) is accompanied by marked intrahepatic cholestasis leading to accumulation of cytotoxic bile acids. Extracorporeal liver support systems efficiently remove bile acids, but their effect on bile acid composition in ACLF is unknown. The aim of the present study was to compare elimination of individual plasma bile acids by albumin dialysis (Molecular Adsorbents Recirculating System, MARS) and fractionated plasma separation (Prometheus). Eight consecutive patients with ACLF underwent alternating 6-hour sessions with MARS or Prometheus in a randomized, cross-over design. Serum samples were obtained before, during, and after each treatment, and individual bile acids including cholic acid and chenodeoxycholic acid (CDCA) were measured by gas chromatography. MARS and Prometheus removed total bile acids to a similar extent (reduction ratio, 45% and 46%, respectively). Both devices cleared cholic acid more efficiently than did CDCA. The molar fraction of CDCA (fCDCA) was elevated at baseline and correlated with the degree of liver dysfunction. Prometheus but not MARS treatments further increased fCDCA. Although both devices eliminate total bile acids to a similar extent, clearance of individual bile acids is different, leading to a slight change of the bile acid profile toward hydrophobic bile acids during Prometheus treatments.

Effect of extracorporeal liver support by MARS and Prometheus on serum cytokines in acute-on-chronic liver failure.

INTRODUCTION: Cytokines are believed to play an important role in acute-on-chronic liver failure (ACLF). Extracorporeal liver support systems may exert beneficial effects in ACLF via removal of cytokines. At present, two systems are commercially available, the Molecular Adsorbent Recirculating System (MARS) and Fractionated Plasma Separation, Adsorption and Dialysis (Prometheus). The aim of this study was to compare the effects of MARS and Prometheus treatments on serum cytokine levels and their clearances. METHODS: Eight patients with ACLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Thirty-four treatments (17 MARS, 17 Prometheus) were available for analysis. Serum cytokines were measured before and after each treatment, and cytokine clearance was calculated from paired arterial and venous samples and effective plasma flow one hour after the start of treatment. RESULTS: Baseline serum levels of interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-alpha), and soluble TNF-alpha receptor 1 were significantly elevated in patients with ACLF. Measurable plasma clearances were detected for all cytokines tested, but no significant changes in serum levels of any cytokine were found after treatments with MARS or Prometheus. In MARS treatments, IL-10 was cleared from plasma more efficiently than IL-6. Clearance of IL-10 was higher in Prometheus than in MARS treatments. CONCLUSION: Cytokines are cleared from plasma by both MARS and Prometheus, but neither system is able to change serum cytokine levels. This discrepancy is probably due to a high rate of cytokine production in patients with ACLF.

Bilirubin kinetic modeling for quantification of extracorporeal liver support.

BACKGROUND/AIM: To provide a measure of treatment dose for extracorporeal liver support (ELS). METHODS: The kinetics of conjugated bilirubin were described by a two-compartment model (Vc, Vp) with central elimination (K) and constant generation rate (G). The transfer of solute between compartments was modeled by intercompartmental clearance (Kpc). The central compartment (Vc) was assumed as a constant fraction of total volume (Vc = 0.3*Vt). RESULTS: Eight patients were studied during 35 treatments lasting 6 h each. The average K, Vt, Kpc, G, and mass of conjugated bilirubin removed were 18.6 +/- 3.9 ml/min, 9.1 +/- 3.8 liters, 103 +/- 108 ml/min, 0.33 +/- 0.15 mg/min, and 641 +/- 275 mg, respectively. The reduction ratio (48 +/- 10%) measured as the change in post- to pre-treatment concentrations underestimated the modeled fraction of bilirubin mass removed (54 +/- 13%) essentially because of significant conjugated bilirubin appearance during treatments. CONCLUSIONS: Kinetic analysis provides an improved measure of treatment dose as generation, distribution, and elimination of conjugated bilirubin are jointly considered.

In vivo quantification of liver dialysis: comparison of albumin dialysis and fractionated plasma separation.

BACKGROUND/AIMS: Artificial liver support represents a potentially useful option for the treatment of severe liver failure. A sufficient 'dose' might be crucial for such treatments to provide a survival benefit. The aim of this study was to compare in vivo efficiency and resulting delivered treatment dose of two commercially available devices that use different therapeutic principles: albumin dialysis (AD, MARS) and fractionated plasma separation (FPS, Prometheus). METHODS: Eight patients with acute-on-chronic liver failure were treated alternately with AD and FPS. Thirty-two treatments at identical blood and dialysate flow rates were evaluated. Clearance and reduction ratio (a measure of delivered treatment dose) were compared for bilirubin subfractions, ammonia and urea. RESULTS: FPS achieved significantly higher clearance for all measured protein-bound and water-soluble markers. This resulted in significantly higher reduction ratios for FPS compared to AD. Unconjugated bilirubin, a marker for strongly albumin-bound toxins, was influenced only by FPS. CONCLUSIONS: FPS provided a higher delivered treatment dose than a matching treatment with AD. Reduction ratios of bilirubin and urea should be reported in clinical studies on liver dialysis, since delivered dose is likely to be linked to the clinical effectiveness of extracorporeal liver support therapies.

Comparative diagnostic value of the breath test and the urine test with 14C-urea in the detection of the Helicobacter pylori infection.

Among 92 patients with chronic gastritis we conducted a synchronous diagnosis of the Helicobacter pylori (H. pylori) infection using a culture and a serological test (IFP), in conjunction with breath and urine tests involving (14)C-urea (BTU-C14 and UTU-C14). The infection was confirmed by isolation in 71 persons (77.2%), the presence of specific IgG in the blood serum was found in 75 (81.5%). In comparison, the BTU-C14 indicated a group of 77 people (83.7%) as infected, and the UTU-C14 a group of 76 (82.6%). In order to determine the diagnostic value (sensitivity, specificity and efficiency) of the latter tests, the results were compared with those of the culture and of the serological tests. It was found that the BTU-C14 test used showed a 100% sensitivity, a 89.5% specificity and a 97.9% efficiency. The UTU-C14 test showed a 100.0% sensitivity, a 94.4% specificity and a 98.9% efficiency in the detection of the H. pylori infection.