Investigations presented in this paper represent the first estimation of patient doses in chest radiography in Montenegro. In the initial stage of our study, we measured the entrance surface air kerma and kerma area product for chest radiography in five major health institutions in the country. A total of 214 patients were observed. We reported the mean value, minimum and third quartile values, as well as maximum values of surface air kerma and kerma area product of patient doses. In the second stage, the possibilities for dose reduction were investigated. Mean kerma area product values were 0.8 ? 0.5 Gycm2 for the posterior-anterior projection and 1.6 ? 0.9 Gycm2 for the lateral projection. The max/min ratio for the entrance surface air kerma was found to be 53 for the posterior-anterior projection and 88 for the lateral projection. Comparing the results obtained in Montenegro with results from other countries, we concluded that patient doses in our medical centres are significantly higher. Changes in exposure parameters and increased filtration contributed to a dose reduction of up to 36% for posterior-anterior chest examinations. The variability of the estimated dose values points to a significant space for dose reduction throughout the process of radiological practice optimisation.

BACKGROUND: Chronic exposure to low-dose radiation doses could be much more harmful than high, short-term doses because of lipid peroxidation initiated by free radicals. The cell membranes and cellular organelles are the main targets for free radicals attack. Peroxidation of cell membrane increases with decreasing dose rate (Petkau effect). The aim of this study was to establish if chronic occupational exposure to low-dose ionizing radiation could induce cell membrane damage. METHODS: Our investigation comprised 77 medical workers: 44 occupationally exposed to ionizing radiation (E), divided in two subgroups-exposed to x-rays (Ex) or gamma rays (En), and 33 controls (C). Informed consent and questionnaire containing dietary, habits, medical factors and exposure history were taken. Groups were matched in gender, age, dietary habits, alcohol consumption, smoking habit, and specific exposure time. Radiation dose accumulated by occupationally exposed over years was calculated on the basis of individual TL-dose records. Besides regular biochemical and cytogenetic tests, lipid peroxidation index, expressed as malondyaldehyde production was performed. RESULTS: Significantly higher lipid peroxidation index was found in workers occupationally exposed to low-dose of ionizing radiation (p>0.000028), which is correlated with age, smoking habit, and significantly correlated with doses. After blood samples in vitro irradiation by 2 Gy of gamma-radiation malondyaldehyde production significantly increased in each group, but were not significantly different between groups. CONCLUSION: Lipid peroxidation index could be considered as triage parameter for further cytogenetic studies in workers chronically exposed to low-dose radiation

BACKGROUND: Since 1976 it has been recognized that an accuracy of ±5% in the delivery of an absorbed dose to a target volume is necessary for successful therapy treatment. Recent studies have concluded that combined standard uncertainty in dose delivery should be smaller than ±3.5 %. The basic radiotherapy requirements initiated some changes in calibration approach. New approach included beam as vital part of calibration chain and also insisted on realization of measurement quality assurance through legal metrology, international key and supplementary intercomparisons, national comparisons, and routine calibration. METHODS: In past twenty years there were three various protocols for absorbed dose determination in radiotherapy that had been based on various principles and various calibration concepts. As there were three conversions in air kerma concept the basic national protocol was changed. We gave up air kerma concept and developed absorbed dose primary standard by ionometric approach and assured appropriate transfer of calibration through four various laboratory levels. The primary standard was realized with combined uncertainty better than 0.3%, 1 s. Transfer of calibration was realized through calibration coefficient determination. RESULTS: Before Code of Practice IAEA 398 was adopted some steps were made in verification of absorbed dose to water primary standard. This standard was established after bilateral intercomparison with Hungarian National Office of Measure (OMH) in 1999 and also after international supplementary comparison organized by International Bureau of Weights and Measures (BIPM) in Sevres, in 2001. Results of the BIPM intercomparison were presented in this paper and they are recognized as national input true value of absorbed dose. Verification of national absorbed dose true value gave us the opportunity to establish new calibration protocol in our radiotherapy centers. We also introduced the new regulatory paper for determination of ionization chamber calibration coefficient. New metrological conditions and calibration manual for radiotherapy chamber were presented in this paper. CONCLUSION: As the method for in-water calibration for gamma and high-energy photons generated in accelerators has been established in our country it gives us possibility to join regional EUROMET program for high-energy photon beam calibration. The first step of calibration in gamma beam quality included also users of high-energy beam in order to fulfill the main metrology goal: calibration in conditions similar to those of users as much as it is possible