Postupanje sa izuzetnim vrednostima u statističkoj analizi velikih voda

In the hydraulic structures design process, the reliable flood estimation is essential for designing the structure. Statistical analysis of observed flood flows, i.e. the flood frequency analysis is one way to obtain the design flood of a specified probability. The problems that can threaten the credibility of flood estimates are related, among other issues, to the treatment procedure of exceptional values (outliers) in the observed flood flow data sets. In this paper a detection of upper and lower outliers in a series of streamflow annual maxima is performed by the Grubbs and Beck statistical test on 68 hydrological stations in Serbia. The data observation period considered is from the establishment of the stations until 2012. The outlier detection results are compared to the previous results obtained for the data processing period until the year 2006.Zbornik radova Građevinskog fakultet

Statistička analiza velikih voda na profilima hidroloških stanica - potreba za promenom pristupa

In most developed countries, practices and research results are translated into standards or guidelines for flood flow assessment, usually with the compulsory application in the design and exploitation of hydraulic structures and systems. This paper briefly presents the draft guidelines for flood flow statistical analysis in gauged basins based on methods of statistical hydrology, intended for practitioners in Serbia. It explains the motivation for composing national guidelines and gives insight into contemporary trends in flood flow assessment in a few selected countries. The content of the draft guidelines is shown, as well as the main conclusions of the expanded research in terms of the proposed methodology for detection and handling of exceptional values. The proposed recommendations for modernization of existing, common engineering practices are highlighted. The paper presents the guidelines at the end of the first from three planned research phases, with the primary aim to encourage public debate which, in pair with the professional review, would lead to the adoption of the guidelines.U većini razvijenih zemalja, iskustva iz prakse i rezultati istraživanja, pretočeni su u standarde ili preporuke za proračun velikih voda, najčešće sa obaveznom primenom u projektovanju ili eksploataciji hidrotehničkih objekata i sistema. U ovom radu ukratko je prikazan nacrt preporuka za proračun velikih voda na izučenim slivovima metodama statističke hidrologije, koji je namenjen domaćoj stručnoj javnosti. Objašnjena je motivacija za izradu preporuka u Srbiji i dat je uvid u savremene tendencije u standardizaciji proračuna velikih voda u nekoliko odabranih zemalja. Prikazan je sadržaj nacrta preporuka, a priloženi su i glavni zaključci proširenog istraživanja u pogledu predložene metodologije za otkrivanje i postupanje sa izuzetnim vrednostima. Sumirane su predložene konkretne preporuke za osavremenjavanje postojeće, uobičajene inženjerske prakse. U radu se stručnoj javnosti predstavlja predlog teksta preporuka nastao posle prve od tri predviđene faze istraživanja, sa prevashodnim ciljem da podstakne javnu raspravu koja bi, uz stručnu recenziju, dovela do usvajanja preporuka

Statistička analiza velikih voda u prisustvu izuzetaka

Flood flow frequency analysis is performed on the series of hydrological observations. The observations introduce uncertainties in the analysis results, inherited from limited data sets, operational difficulties in high flow measurements, flood flow estimates in the rating curve extrapolation zone, as well as different mechanisms of runoff generation. Difficulties in defining flood flow probabilistic model arise in the presence of outliers (significantly larger or smaller value compared to the remaining data set values). The paper provides an overview of methods for the detection of outliers from traditional practice to the latest research results, as well as procedures for outlier treatment in the further statistical analysis, focusing especially on the recommendations from the recently published Bulletin 17C in the USA. The assumptions about the population, procedures of outlier detection, the treatment of transformed data sets, and potential difficulties in the application are highlighted. Statistical tests and procedures are applied to flood data at 70 hydrological stations in Serbia. Analysis of flood flow frequency in the presence of outliers is performed by the methods of the annual maxima and peaks over threshold (POT). The examples include both upper and lower outliers. Comments are given on the differences in the results from the applied outlier detection and treatment procedures. Recommendations to the practitioners are given in the conclusions in order to reduce uncertainty in the flood flow frequency analysis in the presence of outliers.Statistička analiza velikih voda se radi na nizovima hidroloških osmatranja, koja u rezultate ove analize unose neizvesnosti u pogledu ograničene dužine osmatranja, teškoća u merenju vrlo velikih protoka i njihove procene iz zone ekstrapolovanih krivih protoka, kao i zbog različitih mehanizama generisanja oticaja. Definisanje probabilističkog modela velikih voda je otežano i zbog postojanja izuzetaka u nizovima, tj. značajno velikih ili malih vrednosti u odnosu na većinu. U radu se daje pregled postupaka i statističkih testova za otkrivanje izuzetaka od standardnih do najnovijih, kao i načini postupanja sa izuzetnim vrednostima. Najveća pažnja posvećena je otkrivanju i tretmanu donjih izuzetaka, koji u velikoj meri utiču na raspodelu a time i na usvojene računske velike vode. Poseban osvrt je dat na najnovije preporuke iz američkog Biltena 17C. Komentarišu se pretpostavke o raspodeli populacije, procedure testiranja, postupanje sa transformisanim nizovima i ukazuje na moguće poteškoće u primeni. Sama primena testova i procedura prikazana je u praktičnom delu, gde se statistička analiza velikih voda u prisustvu izuzetaka sprovodi za karakteristične primere sa hidroloških stanica u Srbiji na nizovima formiranim metodama godišnjih maksimuma i prekoračenja preko praga. Primeri obuhvataju i gornje i donje izuzetke. Komentarišu se razlike u rezultatima prilikom primene različitih procedura u prisustvu izuzetaka i predlaže niz iskustvenih mera kako bi ocena velikih voda bila što pouzdanija

Izloženost osoblja nuklearne medicine ionizirajućem zračenju u 18F-FDG PET/CT dijagnostici – preliminarna retrospektivna studija

This retrospective study provides an insight into the levels of radiation exposure of six nuclear medicine (NM) staff (four technologists and two nurses) performing routine diagnostic 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) at the University Clinical Centre of the Republic of Srpska, Department of Nuclear Medicine and Thyroid Disorders, Banja Luka, Bosnia and Herzegovina. Data analysis included monthly staff exposure measured with personal thermoluminescent dosimeters (TLD) between June and December 2018, quantified in terms of normalised dose for the whole body [Hp(10)] and dominant hand [Hp(0.07)] and their comparison between each staff member and between the two groups (technologists and nurses). The study goal was to establish how our Department compared with reports from other PET/CT centres worldwide in terms of annual number of procedures and exposure limits and whether there could be room for further improvements in radiation protection. The number of procedures rose considerably from 208 in 2016 to 876 in 2019 and was 423 in the observed seven-month period. Mean individual wholebody exposure dose per GBq of injected 18F-FDG activity, [Hp(10)/A] was 18.55 μSv/GBq for the four technologists and 15.61 μSv/GBq for the two nurses. Mean dominant-hand exposure dose per GBq of injected 18F-FDG activity [Hp(0.07)/A] was 16.99 μSv/GBq and 25.44 μSv/GBq for the two groups, respectively. The average annual cumulative dose for all staff was (1.06±0.29) mSv for Hp(10) and (1.15±0.32) mSv for Hp(0.07). These results are comparable with those of similar studies. Staff doses were well below the annual limits. Nurses received slightly higher extremity doses than technologists. In view of the increasing trends in the number of PET/CT procedures, dose monitoring should be continued to identify exposure hotspots and maintain doses as low as possible.Ova retrospektivna studija pruža uvid u razinu izloženosti ionizirajućem zračenju za šestero zaposlenih (četiri radiološka tehničara i dvije medicinske sestre) koji izvode rutinska dijagnostička ispitivanja primjenom 18F-FDG na PET/CT-u u Kliničkom zavodu za nuklearnu medicinu i bolesti štitne žlijezde Univerzitetskoga kliničkog centra Republike Srpske (Banja Luka, Bosna i Hercegovina). Analiza podataka obuhvatila je mjesečnu izloženost osoblja, koja je od lipnja do prosinca 2018. mjerena osobnim termoluminiscentnim dozimetrima (TLD-ima), a izražena je normaliziranom dozom za cijelo tijelo [Hp(10)] te dozom za dominantnu ruku [Hp(0,07)]. Također, u obzir je uzeta i usporedba tih veličina između svakoga člana osoblja te između dviju skupina (radiološki tehničari i medicinske sestre). Cilj studije bio je usporediti izvješća našega Zavoda i drugih PET/CT centara u svijetu u pogledu godišnjega broja postupaka, granica izloženosti osoblja te mogućnosti uvođenja dodatnih poboljšanja mjera zaštite od zračenja. Ustanovljeno je da se broj postupaka znatno povećao (s 208 u 2016. na 876 u 2019. godini), a tijekom praćenoga sedmomjesečnog razdoblja iznosio je 423. Srednja vrijednost pojedinačne doze za cijelo tijelo po jedinici aplicirane aktivnosti 18F-FDG [Hp(10)/A] iznosila je 18,55 μSv/GBq za četvero radioloških tehničara i 15,61 μSv/GBq za dvije medicinske sestre. Srednja vrijednost doze za dominantnu ruku po jedinici aplicirane aktivnosti 18F-FDG [Hp(0,07)/A] iznosila je 16,99 μSv/GBq i 25,44 μSv/GBq za te dvije skupine. Srednja vrijednost godišnje kumulativne doze za svih šestero zaposlenih iznosila je (1,06±0,29) mSv za Hp(10) i (1,15±0,32) mSv za Hp(0,07). Ovi su rezultati usporedivi s rezultatima sličnih studija. Doze za osoblje bile su znatno ispod propisanih godišnjih limita. Medicinske sestre imale su nešto više vrijednosti doza za ekstremitete (ruke) nego radiološki tehničari. Imajući u vidu tendenciju povećanja broja PET/CT postupaka, potrebno je nastaviti monitoring doza za osoblje kako bi se identificirale faze radnoga procesa koje dovode do najveće izloženosti osoblja, a zatim smanjile doze za osoblje

Radionuclide treatment of metastatic disease in patients with differentiated thyroid carcinoma

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Current concepts of 131I therapy in oncology: Indications, methods and follow up

Radioiodine in various forms (as sodium iodide and as the iodinated compounds MIBG, LIPIODOL, et al.) has been used as a therapeutic agent in oncology. Differentiated thyroid carcinoma (DTC) has been successfully treated by 131I therapy. Neuroendocrine tumors can be treated by palliative therapy, including Meta 131Iodobenzylguanidine therapy (131I-MIBG). Diagnostic 131I or 123I-MIBG scintigraphy is usually performed to image neuroblastoma and malignant pheochromocytoma. Following the establishment of the diagnosis, 131I-MIBG may be applied as a therapeutic agent but with limited success. Hepatocellular carcinoma (HCC) is treated by surgery only in 10% of patients. In others, palliative therapy should be administered. Radionuclide therapy for this disease is a therapeutic option with a major advantage compared to systemic chemotherapy, estrogen and progesterone therapy, and immunotherapy. 131I-lipiodol can be used to treat HCC without side effects. Compared to untreated patients, those who received 131Ilipiodol, showed significantly better survival and a decreased recurrence rate. The modern aspect of the neoplasm treatment involves radioimmunotherapy with radioiodine and some other radionuclides. Monoclonal antibody therapy with radioiodine has been extensively succeeded in the therapy of B-cell non-Hodgkin’s lymphoma, prostate cancer. Radioimmunotherapy is also efficiently performed in some other malignancies such as: medullary thyroid carcinoma, breast cancer, colorectal cancer and malignant brain tumors. Radioimmunotherapy will play a key role in the treatment of malignant diseases, especially hematopoietic neoplasms during this millennium

Radionuklidna terapija bolesnika sa regionalnim i udaljenim metastazama diferenciranog karcinoma štitaste žlezde

Differentiated thyroid carcinoma (DTC) usually has a good prognosis. Nevertheless, 20% to 30% of patients develop recurrences over several decades; two thirds of which appear within the first decade after initial treatment. Reginal metastases (N1) occur in 15%-40% of papillary, and <20% in follicular thyroid carcinomas. Modified regional neck dissection should be performed in cases of regional lymph metastases. Radioiodine treatment should be repeated by administered radioactivity ranging from 5.55 GBq to 7.4 GBq with 3 to 6 month intervals between doses. There is no maximum limit to the cumulative dose of radioactivity that can be administered to patients with persistent disease, provided that individual doses do not exceed 2 Gy of total body exposure. Distant metastases (M1) occur in 10% of DTC patients. Fifty percent of them are present at the time of diagnosis and predict a poor prognosis. Papillary carcinomas develop metastases via lymph nodes in lungs, while follicular carcinomac usually spread hematogeneously into the bones. If possible, surgery is the main treatment of metastatic disease. Radioiodine therapy should be performed in patients with iodine avid metastases. Palliative therapy, including external beam radiotherapy and chemotherapy, is usually performed in non-iodine avid metastases. The 10-year survival rate of 62% is detected in patients with regional recurrences. Their mortality rate has increased in most series. Distant metastases occur more frequently in patients with regional metastases and predict a poor prognosis. The overall survival rate at 10 years from the detection of metastases ranges from 25% to 40%. In our results, we detected a 5-year disease specific survival (DSS) of 67% and 10-year DSS of 55% in patients with iodine-avid lesions, while 15-year and 20- year DSS of 45% were observed. Patients with non-iodine-avid distant metastases had a significantly shorter DSS of 18% after 5 and almost 10 years (p<0.0006). Conclusion: Patients with metastatic DTC can be cured in a significant proportion of patients. In others, durable palliation enables better quality of life and prolonged survival