R Borisova

National Centre of Radiobiology and Radiation Protection, Ulpia Serdica, Sofia-Capital, Bulgaria

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Publications (5)2.74 Total impact

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    Full-text · Book · Jan 2013
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    ABSTRACT: The paper presents the current status of Diagnostic Radiology in Bulgaria. The total number of X-ray systems in 2009 is 2490, with 55.8 % contribution of conventional radiography and fluoroscopy systems, 25.5 % of dental, 7.8 % of computed tomography and 6.9 % of mammography systems. Old X-ray equipment still constitutes a considerable part of the total number, including also high dose CT and angiography systems. The paper presents analysis of results of a large scale national survey of patient doses in Diagnostic Radiology, performed in the period 2007-2009, which covered conventional radiography, mammography, fluoroscopy, including interventional radiology, and computed tomography. Variations in patient dose of up to 18 % were found between departments for the same X-ray procedure. New national diagnostic reference levels for 17 X-ray procedures are presented. The total collective dose of the Bulgarian population was estimated to be 3191 man.Sv. Computed tomography has the highest contribution (30.1 %), followed by conventional radiography (27.3 %), fluoroscopy (20 %) and interventional radiology (9 %). The next national survey should be performed in 2013-2014. The assurance of quality diagnostics at minimum exposure of patients and staff should be of constant concern for the radiological society.
    No preview · Article · Jan 2010 · Rentgenologiya i Radiologiya
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    ABSTRACT: This work is aimed to study the variability of dosimetry results owing to various measurement methodologies for breast dosimetry. This is performed in the frame of the development of a national protocol for breast dosimetry. Doses for standard phantom and group of patients were calculated for two mammography systems from the tube output measured with a calibrated ionisation chamber. The backscatter from the phantom under the chamber contributes to an increase in dosimeter readings of ∼0.8–1.5%, whereas the proximity of the compression plate to the chamber causes increase in the measured air kerma value by 6.5–7%. High value layer (HVL) measured with solid-state detector without corrections for energy dependence was 17% higher than the one measured with ionisation chamber, which causes corresponding overestimation of average glandular dose (AGD). The use of conversion factors based on typical but not measured HVL values leads to 3.5–5.6% overestimation of AGD. Although the sources of uncertainty were taken into account, the difference between the phantom and patient doses was 24%. Some practical recommendations to be included in the national dosimetry protocol are summarised.
    No preview · Article · May 2008 · Radiation Protection Dosimetry
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    ABSTRACT: Patient doses for a few common fluoroscopy-guided procedures in interventional radiology (IR) (excluding cardiology) were collected from a few radiological departments in 13 European countries. The major aim was to evaluate patient doses for the basis of the reference levels. In total, data for 20 procedures for about 1300 patients were collected. There were many-fold variations in the number of IR equipment and procedures per population, in the entrance dose rates, and in the patient dose data (total dose area product or DAP, fluoroscopy time and number of frames). There was no clear correlation between the total DAP and entrance dose rate, or between the total DAP and fluoroscopy time, indicating that a number of parameters affect the differences. Because of the limited number of patients, preliminary reference levels were proposed only for a few procedures. There is a need to improve the optimisation of IR procedures and their definitions and grouping, in order to account for their different complexities.
    Full-text · Article · Mar 2008 · Radiation Protection Dosimetry
  • R Borisova · Ch Ingilizova · J Vassileva
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    ABSTRACT: A study of patient exposure in paediatric diagnostic radiology was conducted in three dedicated paediatric departments. The entrance surface dose was assessed by three methods: direct measurement by thermoluminescent dosemeters, calculation from the dose-area product and from the tube output. The results obtained by the these methods were compared, proving that all of them are applicable for the assessment of paediatric doses. Subsequently, the accumulated data were compared with the mean values from other similar studies and to the reference dose levels set by the Commission of European Communities, which clearly demonstrated the need for further investigation of the paediatric dose levels in Bulgaria and for optimisation of the radiological practice.
    No preview · Article · Mar 2008 · Radiation Protection Dosimetry