Temat: dose - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Luminescence dating of Quaternary sediments – some practical aspects
Autorzy:: Moska, Piotr
Tematy:: luminescence dating
dose rate
equivalent dose; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2025218.pdf Link otwiera się w nowym oknie
Opis:: Luminescence dating is based mainly on the dosimetric properties of quartz and feldspar. These minerals are among the most popular found on Earth, resulting in the possibility of using luminescence methods in practically any environment. Currently, quartz remains the best recognized mineral in terms of dosimetric properties, particularly with regards to results obtained for quartz grains, which are regarded as being the most reliable in luminescence dating. Supporters of luminescence methods are constantly growing, however, these groups do not always have sufficient knowledge to avoid even the most basic of issues that may be encountered overall – from the process of sampling through to the awareness of what a single luminescence result represents. The present paper provides an overview of several practical aspects of luminescence dating such as correct sampling procedures and all necessary information regarding the calculation of the dose rate and equivalent dose with particular reference to potential problems that occur when the age of the sample is being determined. All these aspects are crucial for obtaining a reliable dating result, on the other hand, they remain a potential source of uncertainty.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Evaluation of the quality of mammographic screening examinations performed in the Mazovian Province in 2007-2009
Autorzy:: Ślusarczyk-Kacprzyk, Wioletta
Skrzyński, Witold
Fabiszewska, Ewa
Jankowska, Katarzyna
Grabska, Iwona
Opis:: Background: There is a significant risk of radiation-induced carcinogenesis associated with x-ray mammography. Therefore, the dose received by a woman during mammography should be as low as possible, with an optimal quality of the image. The purpose of this study was to assess changes in the quality of mammographic examinations within three consecutive years of the screening program in the Mazovian Province. Material/Methods: The material for this study consisted of protocols from 114 mammography facilities, developed by physicists from the Mazovian Coordinating Centre in 2007-2009. According to the method published by Dance, individual doses (data from 2007 and 2008) and the value of the absorbed dose in a routine exposure of a standard PMMA phantom with a thickness of 4.5 cm were calculated. Moreover, optical densities of the phantom image (data from the years 2007 to 2009) were measured. Results: The weighted average value of the calculated individual doses in 2008 was lower by 15%, as compared to the value from 2007. Reduction of individual doses is also reflected in the reduced phantom dose in routine exposures performed in consecutive years. In 2007, 2008, and 2009, the phantom dose in routine exposures did not exceed 2.5 mGy in 54%, 70% and 75% mammography facilities (respectively) and the optical density ranged from 1.3 to 1.8. Conclusions: Results from consecutive years showed an evident tendency for decreasing radiation risk, with increasing image quality.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 3.

Tytuł:: Factors affecting high cumulative radiation exposure from paediatric computed tomography
Autorzy:: Tangsiwong, Thipsumon
Trinavarat, Panruethai
Phewplung, Teerasak
Opis:: Purpose: To estimate occurrence rate of high cumulative radiation exposure from paediatric computed tomography (CT), and to determine influential factors on high-dose inclination. Material and methods: Patients below 18 years old receiving at least 50 mSv of a cumulative dose during a 5-year period in a tertiary care centre were retrospectively enrolled. Individual patient characteristics, diagnoses, frequency of examinations, scanner sites, designated scans, and effective doses were recorded. Collective doses were compared among groups of the diagnoses and scanner sites, and regression analyses were applied. Results: Of 2771 patients, 3.2% received individual cumulative doses between 50 and 303 mSv (median, 74 mSv). Frequency of examinations ranged from 1 to 13 times (median, 4 times) per patient. About 70% of the patients had oncological illness. Radiation was predominantly high in a CT simulator that could contribute the percentage of collective dose to twice that of examinations owing to higher scanning parts and CT dose index. Some scanner sites used higher acquisition phases. Regression analysis showed that the number of scanning parts and phases significantly influenced the cumulative dose inclination (p < 0.05) while frequent examinations did not. Conclusions: There was a low occurrence of paediatrics with high dose accumulation. Significant factors affecting potentially high exposure were customized CT protocols in the specific scanners.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: Natural radioactivity in building materials in Iran
Autorzy:: Mehdizadeh, S.
Faghihi, R.
Sina, S.
Tematy:: gamma spectroscopy
absorbed dose rate
annual effective dose
hazard index; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/147658.pdf Link otwiera się w nowym oknie
Opis:: This work presents a comprehensive study of natural radioactivity in building materials used in Iran. For this purpose, 177 samples of five types of building material, i.e. cement, gypsum, cement blocks, gravel and brick, were gathered from different regions of the country and analyzed by gamma spectroscopy to quantify radioactivity concentrations using a high purity germanium (HPGe) detector and a spectroscopy system. According to the results of this investigation, cement samples had maximum values of the mean Ra-226 and Th-232 concentrations, 39.6 and 28.9 Bq/kg, respectively, while the lowest value for mean concentration of these two radionuclides were found in gypsum samples 8.1 and 2.2 Bq/kg, respectively. The highest (851.4 Bq/kg) and lowest (116.2 Bq/kg) value of K-40 mean concentration were found in brick and gypsum samples, respectively. The absorbed dose rate and the annual effective dose were also calculated from the radioactivity content of the radionuclides. The results show that the maximum values of dose rate and annual effective dose equivalent were 53.72 nGy/h and 0.37 mSv/y in brick samples. The radium equivalent activities Req calculated were below the permissible level of 370 Bq/kg for all building materials. The values of hazard indexes were below the recommended levels, therefore, it is concluded that the buildings constructed from such materials are safe for the inhabitants. The results of this study are consistent with the results of other investigations in different parts of the world.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Patient exposure to X-ray radiation during abdominal aorta and lower limb digital subtraction angiography
Autorzy:: Błaszak, Madgalena A.
Majewski, Wacław
Majewska, Natalia
Juszkat, Robert
Opis:: Background: The main aim of this study was to find out what is the risk caused by ionizing radiation during digital subtraction angiography (DSA) for abdominal aorta and lower limb examinations. Material\Methods: The study is based on a large group of patient data subjected to a complex analysis of fluoroscopy time, exposure time, air kerma values, and dose-area product (DAP). Measurements were performed on 449 patients with intra-arterial (IA DSA) contrast administration. Results and Median DAP value for fluoroscopy was 5.4 Gy-cm2 and for exposure 51.7 Gy-cm2. On exposure the patients received 94% of the total DAP although this examination takes only 0.1% of the total examination time. For this reason, small changes in the exposure time may result in a considerable reduction in the radiation received by the patient. There was good correlation between DAP values and the fluoroscopy time (r=0.78), while the correlation between DAP and the exposure time was much poorer (r=0.39). It was also found that gender was a differentiating factor neither both fluoroscopy (F[1, 449]=0.01, p>0.05) nor exposure time (F[1, 449]=0.42, p>0.05).
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: Ionizing radiation and volumetric mammographic density
Autorzy:: Pepłońska, Beata
Mirowski, Mateusz
Kałużny, Paweł
Domienik-Andrzejewska, Joanna
Tematy:: breast cancer
ionizing radiation
mammography
effective dose
mammographic density
organ dose; Pokaż więcej
Wydawca:: Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Powiązania:: https://bibliotekanauki.pl/articles/2152984.pdf Link otwiera się w nowym oknie
Opis:: Objectives Mammographic density (MD) refers to the percentage of dense tissue of an entire breast and was proposed to be used as a surrogate marker for breast cancer. High-dose ionizing radiation (IR) has been recognized as a breast cancer risk factor. The aim of our study was to investigate association between lifetime low dose ionizing radiation (LDIR) and MD. Material and Methods A cross-sectional study included 467 women aged 40–60 years who underwent screening mammography in Łódź, Poland. The digital mammography examination of the breasts included both craniocaudal and mediolateral oblique views. The volumetric breast density (VBD) (%) and fibrograndular tissue volume (FG) (cm3) were determined based on the analysis of mammographic image (“for processing”) using Volpara Imaging Software. The exposure to IR was estimated for each individual, based on the data from interviews about diagnostic or therapeutic medical procedures performed in the area of the neck, chest, abdomen and spine, which involved X-rays and γ rays and the data about the doses derived from literature. Linear and logistic regression were fitted with VBD and FG as the outcomes and organ breast dose, effective dose and number of mammographies as the determinants, adjusted for major confounders. Results The analyses showed no association between VBD or FG and the breast organ dose or the effective dose. The only significant finding observed concerned the association between the number of mammographies and the FG volume with β coefficient: 0.028 (95% CI: 0.012–0.043), and predicted mean FG volume >13.4 cm3 among the women with >3 mammographies when compared to those with none. Conclusions This study does not, in general, provide support for the positive association between LDIR and MD. The weak association of the FG volume with the number of mammographies warrants further verification in larger independent studies.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Autorzy:: Skiba-Kurek, Iwona
Jachowicz, Renata
Niwiński, Krzysztof
Maciejewska, Aldona
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 8.

Tytuł:: Estimation of entrance skin dose and effective dose from abdomen radiography in two diagnostic facilities in Aba, Abia State, South-East Nigeria
Autorzy:: Esu, E. O.
Chiegwu, H. U.
Omojola, A. D.
Eze, E. M.
Tematy:: Entrance skin dose (ESD)
Local diagnostic reference levels (LDRLs)
Dose area product (DAP)
Effective dose (E)
Absorbed dose (DT)
Thermoluminescent dosimeter (TLD)
Kilovoltage peak (kVp)
milliampere-seconds (mAs); Pokaż więcej
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:: https://bibliotekanauki.pl/articles/1839405.pdf Link otwiera się w nowym oknie
Opis:: Medical exposure for abdomen radiography is associated with higher doses compared to X-Rays of the chest and other extremities. The study aims to determine the mean entrance skin dose (ESD) for 104 adult patients between 20-89 years with 2 X-Ray units (A and B) in Aba, South-East Nigeria and to determine the ESD at the 75th percentile to estimate the local diagnostic reference levels (LDRLs). This study also determined the effective dose (E), the dose area product (DAP) and the relationship between absorbed dose (DT) and other parameters. This study will also compare its findings with relevant articles where necessary. The study used 2 functional floors mounted X-Ray units. A total of 208 annealed thermoluminescent dosimeters (TLDs) were used made of Lithium Fluoride, doped with Magnesium and Titanium (LiF: Mg, Ti). Two TLD chips were used per patient. The chips were positioned at the anterior and posterior end of the patient respectively for a given beam area for abdomen radiography. After exposure, a calibrated RadPro TLDcube 400 reader (Freiberg Instrument, Germany) was used to estimate individual patient doses. This was done by multiplying the TLD counts by a pre-determined calibration factor (CF). The mean/75th percentile ESD for facilities A and B was 2.92/4.12 and 3.01/3.67 mGy. The E for facilities A and B was 0.73 and 0.82 mSv respectively. There was a good relationship between the DT with ESD, exit dose (ED) and DAP for facility A, but no relationship was seen with other parameters. The mean ESD was lower compared to the National Council on Radiation Protection and Measurements (NCRP 172) and the American Association of Physicists in Medicine (AAPM) reports respectively. The study proved useful and could serve as a reference point to initiate LDRLs within the South-East zone in Nigeria for abdomen radiography.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Prediction of the cumulated dose for external beam irradiation of prostate cancer patients with 3D-CRT technique
Autorzy:: Giżyńska, M.
Blatkiewicz, D.
Czyżew, B.
Gałecki, M.
Gil-Ulkowska, M.
Kukołowicz, P.
Tematy:: 3D-CRT
cumulative dose
dose prediction
setup error
individualized margins; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/147543.pdf Link otwiera się w nowym oknie
Opis:: Nowadays in radiotherapy, much effort is taken to minimize the irradiated volume and consequently minimize doses to healthy tissues. In our work, we tested the hypothesis that the mean dose distribution calculated from a few fi rst fractions can serve as prediction of the cumulated dose distribution, representing the whole treatment. We made our tests for 25 prostate cancer patients treated with three orthogonal fi elds technique. We did a comparison of dose distribution calculated as a sum of dose distribution from each fraction with a dose distribution calculated with isocenter shifted for a mean setup error from a few fi rst fractions. The cumulative dose distribution and predicted dose distributions are similar in terms of gamma (3 mm 3%) analysis, under condition that we know setup error from seven fi rst fractions. We showed that the dose distribution calculated for the original plan with the isocenter shifted to the point, defi ned as the original isocenter corrected of the mean setup error estimated from the fi rst seven fractions supports our hypothesis, i.e. can serve as a prediction for cumulative dose distribution.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Investigation of high-dose irradiation effects on polystyrene calorimeter response
Autorzy:: Ziaie, F.
Noori, A.
Tematy:: polystyrene calorimeter
electron beam
absorbed dose
high dose
high impact polystyrene (HIPS); Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/146133.pdf Link otwiera się w nowym oknie
Opis:: In this work attempts have been made to investigate the variation of polystyrene calorimeter response after frequent irradiations with an electron beam. Polystyrene calorimeters are routinely used in every radiation processing center as a traceable to NPL primary standard dosimeter. Thus, self designed high impact polystyrene as the calorimeter core was irradiated several times up to many thousands of kGy doses. After each irradiation, the specific heat capacity of the polystyrene as the main changeable parameter was measured using the differential scanning calorimeter system (DSC) in the practical temperature range of polystyrene calorimeter. Therefore, correction factors to calculate the precise absorbed dose were obtained. At the final stage, several these calorimeters were irradiated simultaneously along with two Risoe standard calorimeters and another correction factor for each tested calorimeter was calculated.
Dostawca treści:: Biblioteka Nauki

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