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L. Krynke et al.. / Medical Physics in the Baltic States 7 (2009) 93 - 95 Average max/min DLP values – 875/148 mGy x cm. Variation of kV and mA parameters for chest examination between CT rooms - 110-130 kV; 200-500 mA; Spine examination mGy x cm 440 390 340 290 240 190 140 CT room Spine DRL 300 mGy x cm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Fig. 3 Average DLP values in comparison with spine DRL value – 300 mGy x cm Average values for spine examination for 3 of medicine centers (or 21%) are above DRL value (300 mGy x cm). Average max/min DLP values – 471/214 mGy x cm. Variation of kV and mA parameters for spine examination between CT rooms – 120-140 kV and 200-600 mA; For pelvis and abdomen examination the data is being collected still to evaluate situation more confidently. For head, chest and spine examinations was found compliance to established DRLs for these examinations. Wide variation of parameters for the same examination, but different CT units and medicine centers could be a reason of variation of dose values. The relation between exceeded dose values and type of CT unit was not found. Observing the data, were spotted 2 medicine centers, with enlarged average DLP values for all established DRLs in CT. 2 medicine centers were found exceeding DRLs for 2 of examinations and remainder centers exceeds DRLs for 1 of examinations. 4. Conclusions In this study were made first steps for establishment DRLs in computed tomography in Lithuania. First- new DRLs values in units of dose length product (mGy x cm) were proposed and approved by director of Radiation Protection Centre. Second - by evaluating 95 additional data, were found several medicine centers, within average dose values are above proposed reference levels. Additional data collection and evaluation from medicine centers with exceeded average DLP values is intended in a short term future. During further investigation of situation in computed tomography, there is intention to settle DRLs for more detailed examination (cervical spine, thoracic spine, lumbar spine; different phase of abdomen examination etc.). After national DRLs establishment it is essential for all medicine centers not exceed these levels. For this reason regular local compliance checking with DRLs is necessary. Medicine physicist availability, performing these procedures, should bring essential help. At this moment medicine physicists are involved only in big medicine centers activity. 5. References 1. Guidance on the establishment and use of diagnostic reference levels for medical X-Ray examination, Institute of Physics and Engineering in Medicine, Report 88, York 2004. 2. European guidelines on quality criteria for computed tomography. Report EUR16262. European Community, Brussels, Belgium, 1998. 3. Dosimetry in diagnostic radiology: an international code of practice technical reports series No 457, p. 188-196. 4. COUNCIL OF EUROPEAN UNION (1997): ‘Council Directive 97/43/EURATOM of 30 June 1997 on health protection of individuals against the dangers of ionizing radiation in relation to medical exposure 5. Publication of diagnostic reference levels for radiological and nuclear medical examinations Diagnostic reference levels, 2003, p. 3, (Available on http://www.bfs.de/en/ion/medizin/referenzwerte01.pdf), Accessed on 25 September 2009. 6. J. Clarke, K. Cranley, J. Robinson, H. S. Smith, A. Workman, Application of draft European Commission reference levels to a regional CT dose survey, The British Journal of Radiology, 73, 2000. p. 43-50. 7. Decreto legislativo 26 maggio 2000, n. 187, p.15, (Avialiable on http://www.ifinmed.it/download/Dlgs187_00.pdf), Accessed on 25 September 2009.
MEDICAL PHYSICS IN THE BALTIC STATES 7 (2009) Proceedings of International Conference “Medical Physics 2009” 8 - 10 October 2009, Kaunas, Lithuania INFRARED SPECTROSCOPICAL STUDIES OF DISTRIBUTION OF CHEMICAL COMPONENTS IN URINARY STONES Milda PUČETAITĖ*, Valdas ŠABLINSKAS*, Vaiva HEDRIXSON**, Zita KUČINSKIENĖ**, Arūnas ŽELVYS***, Feliksas JANKEVIČIUS*** *Dept. of General Physics and Spectroscopy, Faculty of Physics, Vilnius University; ** Dept. of Physiology, Biochemistry and Laboratory Medicine, Faculty of Medicine, Vilnius University; ***Centre of Urology, Vilniaus University Hospital Santariskių klinikos, Faculty of Medicine, Vilnius University Abstract: Kidney diseases which cause the occurrence of urinary stones are frequent in human pathology. The formation process of the stones is not fully understood therefore the studies of chemical composition and structure are of great importance. The means of Fourier transform infrared spectroscopy (FTIR) were used to determine the composition of the stones while FTIR microscopy was used to create chemical maps of cross-sectioned stones. The data from the study were used to analyze the formation process of the stones. Keywords: urinary stones, FTIR, microspectroscopic surface reflectance imaging 1. Introduction The composition and structure of urinary stones is complex and depend on a variety of factors which include diet, sex, environment, metabolism, etc. The identification of the components and structure of the stone enables to find out the underlying cause of the disease, prescribe treatment and prevent recurrences [1]. The qualitative and quantitative analysis of urinary calculi is challenging because of their usually small size, fragility, heterogeneous composition. Fourier transform infrared spectroscopy (FTIR) is easy and rapid method to obtain quantitative and qualitative information about chemical composition of the calculi even from small amount of the substance. In addition, this method enables to distinguish such similar components in the stones as calcium oxalate mono- and dihydrate. Microspectroscopic surface reflectance imaging is an informative method for analyzing morphology of cross-sectioned stones [2]. 2. Experimental Urinary stones for this study were surgically removed from patients in Vilnius University hospital Santariskiu klinikos. 2 mg of homogenized sample was finely grounded with potassium bromide (KBr) powder of spectroscopic purity and converted into a pellet using manually operated hydraulic press “Specac” exerting a pressure of 10 tons. The pellet was placed in the sample compartment of “Vertex 70” spectrometer from “Bruker” in the path of infrared radiation emitted by 96 “glowbar” light source. The spectrum was obtained using liquid nitrogen cooled MCT (mercury cadmium telluride) detector with 4 cm -1 spectral resolution. The spectrum was then matched against library spectra to identify various stone components. The cross-sectioned stones were fixed on glass microscope slides using two-component epoxidic glue and polished. Spectra were obtained using FTIR microscope “Hyperion 3000” from “Bruker” with single element MCT detector. The resolution of the spectrometer was set to 2 cm -1 . False-colour images representing the distribution of different chemical components in the urinary stones were obtained by integrating the area under the spectral band of specific chemical component. OPUS software was used for this purpose. 3. Results and discussions In this study, the components found in the stones were: calcium oxalate (mono- and dihydrate), phosphates (carbapatite and brushite), uric acid and struvite. The majority of stones (~78%) are constituted from calcium oxalate with phosphate deposits. Some of the stones (~17%) are constituted from pure uric acid (Fig. 1) and the others (~5%) – from three components: calcium oxalate, phosphate and struvite (Fig. 2). FTIR spectroscopy allows distinguish two very similar substances: calcium oxalate monohydrate and calcium oxalate dihydrate [3]. Such analysis in this work was based on the position of C-O stretching spectral band. This band shifts from 1317 cm -1 for calcium oxalate
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