FIRST MOBILE LINEAR ACCELERATORS IN SERBIA PRELIMINARY TLD

FIRST MOBILE LINEAR ACCELERATORS IN SERBIA - PRELIMINARY TLD RESULTS - Olivera Marinkovic(*), Vedrana Prokic(**), Stefan Rafailovic(*), Zoran Mirkov(**) (*) Serbian Radiation Protection and Nuclear Safety Agency, Belgrade (**) Serbian Institute of Occupational Health “Dr Dragomir Karajovic”, Belgrade

THERMOLUMINESCENT DOSIMETRY Serbian Institute of Occupational Health “Dr D. Karajovic” q Harshaw TLD Reader Model 6600 (12 th serial unit) and 12000 dosimeters (Li. F: Mg, Ti) were bought 1991 q Come to the Laboratory for personal dosimetry in January, 1992. Those were the days: - PC 286 - DOS and still operate: - REMSMENU software - CGCD Programme (Computerised Glow Curve Deconvolution) 2/15

ETAM Method for Exposure Conditions Reconstruction Marinkovic, Olivera 1; Spasic Jokic, Vesna 2 1 Serbian Institute of Occupational Health “Dr Dragomir Karajovic”, Belgrade 2 Faculty of Technical Sciences, University of Novi Sad, SERBIA Third European IRPA Congress 2010 June 14 18, Helsinki, Finland

ETAM q Elapsed time correlate with one-shot exposure q Broadly applicable ETAM Exposure Time Assessment Method 4/15

Li. F Fading 5/15 a) b) a) Glow curve shape: a) short elapsed time; b) long elapsed time between irradiation and read-out

CARD HOLDERS STANDARD FILTERED HOLDER - Tissue equivalent filter - Skin equivalent filter A card has two chips (ii) & (iii) beneath different filters! 6/15

GLOW CURVE SHAPE 7/15 b) (ii) “regular” (iii) “irregular” a) “regular” -Many causes for irregularity. -Permanent crystal defect. -Non ionizing excitation.

Mobile Container/Vehicle Inspection System - Serbia has a few 6 Me. V NUCTECH MT 1213 LH - Improvement of cross border control - Cross border area usually is not too big Three decades of mobile linear accelerators in human medicine in China !!! 8/15

DOSIMETRY – points of measurement 9/15 PROTEKTIVE LINE (FENCE) B N C D E F O beam MT 1213 LH A G M P L K J I H Ambient dose equivalent rate (μSv/h) point B C E F G H I J L K value 0. 15 0. 6 1. 2 1. 1 1. 3 0. 8 0. 2 0. 09 0. 08

TLD RESULTS Ø A set of TL dosemeters (two crystals per card packed in standard filtered holders, has been placed around NUCTECH MT 1213 LH Mobile Container/Vehicle Inspection System at different distances to collect radiation during a month. Ø At the same time, eight TL dosimeters which were exposed to three scans were read-out three hours later (Table 2). Crystal (ii) has position below 1 cm tissue equivalent filter and crystal (iii) has position below skin equivalent filter. 10/15

TLD RESULTS – Table 2 Three scans (TLD in air) Check crystals (**) N o. TLD bar-code H 11039 0. 9709 1. 75959 11 m right back 13. 25 12. 85 C 4232 1. 0630 7. 64617 19 m left front 13. 52 13. 86 D 2510 0. 8061 1. 60664 9 m left front 13. 16 13. 84 I 2985 1. 0260 5. 64319 9 m central back 13. 60 12. 85 F 4158 0. 8874 7. 79779 8 m right front 13. 15 13. 91 J 4033 1. 9780 11. 6002 13 m left back 14. 12 14. 07 E 4223 1. 0360 1. 33133 6 m central front (beam) 12. 68 13. 21 B 10244 1. 1740 2. 01362 25 m left front 12. 37 12. 74 - 5537 0. 8372 2. 60281 Not exposed (background) 13. 35 12. 40 - 4113 0. 8786 1. 24128 Not exposed (background) 13. 74 13. 54 average 1. 06572 4. 324269 13. 294 13. 3286 stdev 0. 340241 3. 628713 0. 505573 0. 592033 (ii) (n. C) Distance from spot (different angles) 11/15 (iii) (n. C)(*) (ii) (n. C) (iii) (n. C)(*)

ULTRAVIOLET RADIATION ØTLDs exposed to ultraviolet radiation ØSUNVISION 240, Dinamic FAN solarium machine ØExposure 20 minutes ØREAD OUT AFTER 20 HOURS ØHEATING EFFECT 12/15

COMPARASION: TLD-UV 13/15 SUNVISION 240, Dinamic FAN solarium machine NUCTECH MT 1213 LH (C) (J) (E)

DISCUSION q This paper doesn’t give integral values for doses but strongly testify on intensive low energy field around linac. q Average signal (in n. C) for TLDs exposed two months around linac was only 50% higher than for TLDs exposed one day (low energy peak, spontaneous contamination ). q. Are we sure that health risk is well known? 14/15

THANK YOU FOR YOUR ATTENTION Gaius Flavius Valerius Aurelius Constantinus commonly known as Constantine I, (272 -337) Birthplace: Naissus, Illyria (modern-day Niš, Serbia) The Edict of Milan (Edictum Mediolanensium, 313) was a letter signed by emperors Constantine I and Licinius that proclaimed religious toleration in the Roman Empire