Determining the probability of locating peaks using computerized peak-location methods in gamma-ray spectra as a function of the relative peak-area uncertainty.

The probabilities of locating peaks with a high relative peak-area uncertainty were determined empirically with nine types of peak-location software used in laboratories engaged in gamma-ray spectrometry measurements. It was found that it is not possible to locate peaks with a probability of 0.95, when they have a relative peak-area uncertainty in excess of 50%. Locating peaks at these relatively high peak-area uncertainties with a probability greater than 0.95 is only possible in the library-driven mode, where the peak positions are supposed a-priori. The deficiencies of the library-driven mode and the possibilities to improve the probabilities of locating peaks are briefly discussed.

Systematic influences on the areas of peaks in gamma-ray spectra that have a large statistical uncertainty.

A method is presented for calculating the expected number of counts in peaks that have a large relative peak-area uncertainty and appear in measured gamma-ray spectra. The method was applied to calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software.

Novel method of measurement of radon exhalation from building materials.

In the era of the energy saving policy (i.e. more air tight doors and windows), the radon exhaled from building materials tends to increase its concentration in indoor air, which increases the importance of the measurement of radon exhalation from building materials. This manuscript presents a novel method of the radon exhalation measurement using only a HPGe detector or any other gamma spectrometer. Comparing it with the already used methods of radon exhalation measurements, this method provides the measurement of the emanation coefficient, the radon diffusion length and the radon exhalation rate, all within the same measurement, which additionally defines material's radon protective properties. Furthermore it does not necessitate additional equipment for radon or radon exhalation measurement, which simplifies measurement technique, and thus potentially facilitates introduction of legal obligation for radon exhalation determination in building materials.

Natural radioactivity in lignite samples from open pit mines "Kolubara", Serbia--risk assessment.

Coal as fossil fuel mainly contains naturally occurring radionuclides from the uranium and thorium series and (40)K. Use of coal, primarily in industry, as a result has dispersion of radioactive material from coal in and through air and water. The aim of this study was to determine the activity concentrations of natural radionuclides in coal samples from open pit mines "Kolubara" and to evaluate its effect on population health. The results showed that all measured and calculated values were below the limits recommended in international legislation.

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry--part II (volume sources).

The second part of an intercomparison of the coincidence summing correction methods is presented. This exercise concerned three volume sources, filled with liquid radioactive solution. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing corrective factors for several energies of (152)Eu and (134)Cs, and different source-to-detector distances. They are presented and discussed.

On the long-term stability of calibration standards in different matrices.

In order to assure Quality Control in accordance with ISO/IEC 17025, it was important, from metrological point of view, to examine the long-term stability of calibration standards previously prepared. Comprehensive reconsideration on efficiency curves with respect to the ageing of calibration standards is presented in this paper. The calibration standards were re-used after a period of 5 years and analysis of the results showed discrepancies in efficiency values.

The direct measurement of 57Co activity by the sum-peak method.

The direct measurement of the activities of (57)Co sources by application of the sum-peak method recently developed by Novkovic et al., is described in this paper. The comprehensive assessment of the uncertainty budget of the activity of the measured sources has been analyzed. The presented method is successfully tested using an HPGe spectrometer with efficiencies of 50%. The accuracy of this method is confirmed to be comparable with the commonly used methods of the activity measurement of (57)Co.

Treatment of the rectal cancer in casuistic Clinic for Abdominal Surgery, Clinical Centre of the University of Sarajevo (2006.-2010.).

Malignant disease of the colon and rectum is the most often human neoplasm which comprises about 30% of all digestive tumours. Thereat, cancer of the lower end the colon (rectum) comprises 45 to 48% of all CRC (colorectal cancers). According to "American Society Cancer", only lung and prostate cancer in men and breast and cervix cancer in women are more frequent than CRC. The incidence of colorectal cancer is 20 to 30/100.000 citizens. Rectal cancer is the result of interection of disturbed genetic factors with external factors. The first surgical treatments began with Faget, who did the first rectal extraperitoneal excision (1739). It was improved by Ernest Milles in 1908, and in 1923, Hartman did the resection without anamnesis. In the middle of 20th century, Dixon defined the resective interventions and in Litre did a colostomy. The aim of this study is point out the necessity of early diagnosis and protocolar chirurgical end oncological approach to the treatment of this malignant disease which must be done before choosing any operative procedure in order to prevent postoperative morbidity. On the material of the Clinic for Abdominal Surgery at the Clinical centre University of Sarajevo, during the four-year period (from 2006 to 2010), out of the 406 patients with CRC, 261 of them (64.3%) had cancer of the final part of the colon and rectum. In this case, all the time of the treatment, protocol was strictly applied. Primary surgery was performed on the early stages of the disease. Radiochemotherapy (RCT) followed by operation after 6 to 8 week is applied in the progressive state of the disease with the penetration of the meso rectal fascia with positive lymph-gland assessment (NMR-nuclear magnete resonance). Out of 261 operated patients, 5 of them (1.9%) underwent transanal resections where the tumour was up to 2 cm; 104 patients (39.8%) underwent rectal resection with TME (II and III tumour states of recto-sigma); 24 (9.2%) patients uderwent amputation; 156 (22.4%) underwent left chemicolectomy with rectal resection and 29 (11%) underwent intersphincteric colo-trans-versal-anal anastomosis. The operation by Hartman was performed on 44 (16.8%) patients and colostomy on 10 (3.8%) patients in emergency service. In the tumours with low localisation we do low colo-transversal-rectal or ultra-low intersphincer colo-anal anastomosis. Total meso rectal excision and lymhadenectomy is our priority. We fully respect the oncologic approach, i.e. complete removement of the affected organ with the lymphovascular arcade. Operative lethality up to 30 days was 2.5% (comorbidity, thromboembolism). Owing to combined protocolar approach of surgical and radiochemotherapy, extirpational interventions are not so frequent any more compared with resections with low and ultra-low anastomosis. Team work and close cooperation of oncologic team of physicians (surgeons, gastroenterologists, pathologists, oncologists, radiotherapeutists) as well as respect for the protocol of the treatment are the most important factors of a successful oncologic surgery.

A simple method for determination of natural and depleted uranium in surface soil samples.

A simple and efficient method for determination of uranium content in surface soil samples contaminated with depleted uranium, by gamma ray spectrometry is presented. The content of natural uranium and depleted uranium, as well as the activity ratio (235)U/(238)U of depleted uranium, were determined in contaminated surface soil samples by application of this method.

Experimental determination of the HPGe spectrometer efficiency curve.

A review of the calibration procedures of the semiconductor HPGe spectrometer is presented in this paper. Calibration standards were prepared using the standardized radioactive solution of the common monoenergetic radionuclides mixture and standardized multigamma (152)Eu solution. The matrix materials were spiked using the activated carbon, and homogenized mechanically or by suspension in C(2)H(5)OH. Experimentally determined efficiency curves were compared with those obtained by Monte Carlo simulation.

Determination of the specific alpha activity of thick sources with a large area ZnS(Ag) scintillation detector.

A method for determining the specific alpha activity of thick sources using a large area ZnS(Ag) scintillation detector is presented. In this method a quadratic relationship between the detector response and window thickness is assumed. This method provides a quick estimation of alpha activity in the sample, so it is an indicative method. The aim of this experimental work is to approve theoretical assumption and to develop a standard routine method for absolute alpha measurements of thick contaminated environmental sources. For this purpose reference material U(3)O(8) and spiked standards of soil were used. Measurements of contaminated soil samples from south Serbia showed the practical application of this method.