Combination of the gamma emission tomography and the virtual point-detector methods for calculating radioactive waste drum by non-destructive assays

In this study, the gamma emission tomography and the virtual point-detector method were combined to calculate the efficiency of the radionuclide inside the radioactive waste drum. Therefore, the radioactivity of the radionuclide inside the waste drum has been calculated. The results showed that the source location was determined by the gamma emission tomography for good results with the experimental value. The discrepancies between measured and true activity were smaller than 13% for the sand matrix.

Quantitative Accuracy of Low-Count SPECT Imaging in Phantom and In Vivo Mouse Studies

We investigated the accuracy of a single photon emission computed tomography (SPECT) system in quantifying a wide range of radioactivity concentrations using different scan times in both phantom and animal models. A phantom containing various amounts of In-111 or Tc-99m was imaged until the activity had decayed close to background levels. Scans were acquired for different durations, employing different collimator pinhole sizes. VOI analysis was performed to quantify uptake in the images and the values compared to the true activity. The phantom results were then validated in tumour-bearing mice. The use of an appropriate calibration phantom and disabling of a background subtraction feature meant that absolute errors were within 12% of the true activity. Furthermore, a comparison of in vivo imaging and biodistribution studies in mice showed a correlation of 0.99 for activities over the 200 kBq to 5 MBq range. We conclude that the quantitative information provided by the NanoSPECT camera is accurate and allows replacement of dissection studies for assessment of radiotracer biodistribution in mouse models.

Patient-Specific Three Dimensional (3D) Dosimetry for 90Y Ibritumomab Tiutexan (Zevalin®) in Patients with Follicular Lymphoma.

Objectives: Dosimetry calculations for radioimmunotherapy are usually performed using a two dimensional (2D) protocol based on planar whole body (WB) scintigraphy and fixed organ masses derived from the MIRD anthropomorphic model (Wiseman GA et al., J Nucl Med2003:44;465–74). We compared the absorbed dose obtained with this method with an approach involving patient-specific 3D dosimetry based on quantitative SPECT and patient organs mass estimation. Methods: Five patients with follicular lymphoma in partial or complete remission underwent a CT scan, and five successive WB and SPECT scans at day 0 (D0) 1 hour, D0 4 hours, D1, D4 and D6 after injection of 111In ibritumomab tiutexan (185 MBq). WB scans were used to estimate the activity in the liver, spleen and kidneys. SPECT images were reconstructed using a quantitative processing including corrections for scatter, attenuation, and partial volume effect. The organs mass and activity values were estimated in 3D volumes of interest manually drawn on the CT scan and registered to the SPECT scan. Absorbed doses after administration of 15 MBq/kg of 90Y ibritumomab tiutexan were derived from both 111In WB and SPECT data accounting for the fractions of injected activity measured in each organ at the five time points. Results: The mean differences between the organs mass estimated from the patient CT and the MIRD anthropomorphic model were 8%, 105% and 12% for liver, spleen and kidneys respectively. Measurements on an abdominal phantom filled with 111In showed that errors in organ activity estimates ((estimated activity - true activity)/true activity) for WB and SPECT protocols, were 37% and −6% respectively in the liver, 20% and −10% in the spleen, −26% and −23% in the left kidney, and 47% and −9% in the right kidney. Patient liver, spleen and kidney activity values determined from the SPECT scans were on average 35%, 60% and 39% less than those found from the WB scans. The absorbed doses calculated with the 3D patient-specific protocol were less than those calculated with the 2D protocol, by 46±14%, 77±14% and 70±22% in the liver, spleen and kidneys respectively, except in one patient kidney where SPECT dose exceeded WB dose by 2%. Conclusions: Accounting for patient-specific organ mass and using SPECT activity quantification have a great impact on estimated absorbed doses of 90Y ibritumomab tiutexan if compared with the 2D protocol. This method could improve the correlation between dosimetry and clinical consequences of this treatment, especially in view of dose escalation with stem cell rescue.

Importance of Neutralizes in the Stripping Fluid in a Simulated Healthcare Personnel Handwash

The Food and Drug Administration (FDA) healthcare personnel handwash procedure allows for the use of a non-neutralizing stripping fluid after washing with an antimicrobial handwash product. The antimicrobial in the handwash product can remain active up until the time of neutralization or plating. A modified healthcare personnel handwash procedure using a pigskin substrate and a 4% chlorhexidine gluconate handwash product was used to demonstrate the need for a neutralizer in the stripping fluid. When tests were run with and without neutralizers in the dilution blanks, but with adequate neutralizers in the stripping fluid, there were no significant differences (p>.05) between results obtained after five washes or after each wash. When tests were run with a non-neutralizing stripping fluid, significant differences were noticed in the first and the fifth wash (p<.05), and in the presence or absence of neutralizers in the dilution blanks (p<.05). The data generated indicate that in order to determine the true activity of an antimicrobial handwash product, an adequate neutralizer should be incorporated into the stripping fluid and not just the dilution media. They also suggest that neutralizer carry-over from the stripping fluid is not a valid concern.

The Growth of The Anti-Jewish Stereotype

There are three good reasons at the present time to try to arrive at an historical model to explain the development of anti-Jewish stereotyping and prejudice, and in this way, provided it is worked out at a sufficiently high level of abstraction, at an historical model of racism.Thefirstreason is that both the Netherlands and its neighbours are increasingly faced with racism and that for a good line of action it is necessary to collect all kinds of knowledge. Moreover, it is desirable that historians prove willing to co-operate by making their particular contribution to this collection of knowledge. Thesecondreason is that in contemporary thinking about history a tendency seems to have made itself felt that considers the narrative element of history as the only true activity of the historian, so that a hypothetical-deductive, one might say Popperian, approach to the past seems to be wrong. Although I do not want to enter into a methodological discussion, which I am glad to leave to my friend P. H. H. Vries, who has very capably formulated a point of view that I subscribe to, my intention is to show the usefulness of an abstract, partially mathematical, model in this article. By the way, in the framework of an article it is impossible to present an extensive test of the predictions of the model by means of source material. It can only be hinted at. This article is not non-narrative because I want it to be non-narrative, but because of lack of space. A full exposition would need a book. I shall only present in summary what I hope is the logical argument that lies at the basis of the model.

Assessment of telemetric motion sensors for studies of activity

Radio transmitters containing motion-sensitive devices that changed the pulse rate (mode) in response to movement were evaluated as a means for studying activity of black bears (Ursus americanus). Two types of motion sensors were used: tip switches gave immediate indications of activity, whereas reset motion sensors extended the active mode signal for 5 min. Locational accuracy was less affected by reset sensors than tip switches, and reset sensors facilitated activity monitoring of weak or fading radio signals. Tip switches were more useful in making continuous judgements of activity, and may be used to differentiate types and degrees of activity. For both sensors true activity could be distinguished from comfort movements. Also, both motion-sensitive transmitters gave indications of activity that compared well with hourly movements of bears; these transmitters were more sensitive to localized movements than measurements between radio locations determined by triangulation and were more practical because only one observer was necessary. Motion sensors also gave more reliable indications of activity than changes in signal integrity.

Analysis of Anticoagulation Activities of Heparins - Is usp Heparin Assay Reliable?

The in vitro “over-all” activity of heparins was analyzed by the technique of rigidity measurements with plasmas upon recalcification. This technique allows the measurement of the entire clotting process of a heparinized plasma, and is thus more sensitive and reliable than clotting time determination. Contrary to its action to the clotting of whole blood, heparin reduces the final rigidity of a plasma clot only when the degree of heparinization exceeds certain limit. A log-log plot of clotting half-time vs. amount of heparin may be used to compare the anticoagulation activity of various heparins in human plasma and in sheep plasma. Results show that heparin with molecular weight around 20,000 possesses highest specific activity, the activity drops sharply when molecular weight increases or decreases. The anticoagulation activity of heparin in human plasma, expressed by the increase in clotting half-time is up to 100 times more effective than that in sheep plasma but responds less sensitively to the change in heparin concentration. Using the same heparin standard, the specific activity of certain heparin fractions assayed in human plasma differs from that assayed in sheep plasma. The discrepancy increases with the decrease in heparin molecular weight. The discrepancy was also observed with some heparins of different tissues and sources. The USP heparin assay, which uses sheep plasma as the assay medium, therefore does not necessarily reflect the true activity in human blood clotting system.