Approach to radionuclide therapy dosimetry planning

Control of radiation dose absorbed in pathological volume represents one of the challenging issues in the implementation of radionuclide therapy (RNT). This paper presents new approach based on estimation of radiopharmaceutical (RP) accumulated activity value in tumor volume, based on planar scintigraphic images of the patient and calculated radiation transport using Monte Carlo method, including absorption and scattering in biological tissues of the patient, and elements of gamma camera itself. In our research, to obtain the data, we performed modeling scintigraphy of the vial with administered to the patient activity of RP in gamma camera, the vial was placed at the certain distance from the collimator, and the similar study was performed in identical geometry, with the same values of activity of radiopharmaceuticals in the pathological target in the body of the patient. For correct calculation results, adapted Fisher–Snyder human phantom was simulated in MCNP program. In the context of our technique, calculations were performed for different sizes of pathological targets and various tumors deeps inside patient's body, using radiopharmaceuticals based on a mixed β–γ-emitting (131I, 177Lu), and clear в-emitting (89Sr, 90Y) therapeutic radionuclides. Presented method can be used for adequate assessment of the absorbed dose in the regions of interest on the basis of patient planar scintigraphy

Vegetation and climate changes around the Lama Lake, Taymyr Peninsula during the Late Pleistocene and Holocene reconstructed from pollen records

A continuous lacustrine sequence from the western part of Lama Lake (69°32'N, 90°12'E),completed by a peat sequence from the lake catchment provides the first detailed environmentalreconstruction for the Late Glacial and Holocene on the Taymyr Peninsula. Scarce steppe-likecommunities with Artemisia, Poaceae, and Cyperaceae dominated during the Late Glacial. Tundra-like communities with Betula nana, Dryas, and Salix grew on more mesic sites. There are distinctclimatic signals, which may be correlated with the Bølling and Allerød warmings and Middle andYounger Dryas coolings. The Late Glacial/Preboreal transition, at about 10,000 14C yr BP, wascharacterized by changes from predominantly open herb communities to shrub tundra ones. Larchforest might have been established as early as 9700-9600 14C yr BP, whilst shrub alder came tothe area ca 9500-9400 14C yr BP, and spruce did not reach area before ca 9200 14C yr BP. Spruce-larch forests with shrub alder and tree birch dominated the vegetation around the Lama Lake fromca 9000 14C yr BP. Dwarf birch communities were also broadly distributed. Role of spruce in theforest gradually decreased after 4500 14C yr BP. Vegetation cover in the Lama Lake area becamesimilar to modern larch-spruce forest ca 2500 14C yr BP. A pollen-based biome reconstructionsupports a quantitative interpretation of the pollen spectra. Climate reconstructions obtained withinformation-statistical and plan-functional-type methods show very similar trends in reconstructedJuly temperature since ca 12,300 14C yr BP, while precipitation anomalies are less coherent,especially during the Late Glacial-Holocene transition