Página 177 - irpa

177 ST 3.1 – Protección radiológica en radiodiagnóstico (orientada a intervencionismo)
DOSE RATES IN REAL TIME FOR INTERVENTIONAL FLUOROSCOPY
PROCEDURES
Lourenco, Jose Carlos 1; Paschuk, Sergei1 ; Schelin, Hugo2*;
Denyak, Valeriy2; Santos, Cesar 3
1 Federal University of Technology. Brasil.
2 Pelé Pequeno Príncipe Research Institute. Brasil.
3 Londrina State University. Brasil.
* Responsible author, email: schelin2@gmail.com
The objective of the present work was to develop a system to estimate the equivalent doses of
ionizing radiation in real-time during interventional fluoroscopy procedures. We used the remote
system fluoroscopy control manually operated at 50 kVp and 30 mA and the ionization chamber
Ludlum Model 9DP. In the experimental phase a PMMA simulator was used to measure the
scattered radiation. The dose rates were collected in 3D in relation to the main beam of 19, 38,
76 and 152 cm and the height with the same numeric values, corresponding to thirteen points
with angles of 7O, 14O, 45O, adopting the inverse distance square law. The dose rates above
5μSv/h were considered and the reproducibility of the measurements. The algorithm of the
Chauvenet criterion was used to eliminate the discrepant measures, selecting the dose rates
that were above the average. The resulting measures of these selections were used to build the
isodose of the dose rates. To visualize the dose rates real-time in 3D an ionization chamber was
placed on top of the fluoroscopy table. The collected data were sent to the computer for
processing in order to determine the estimated dose rates indirectly in relation to the
predetermined isodoses and to the positioning of the staff in the interventional procedures. The
dose rates and the cumulative dose are shown in real time through a TV monitor placed in a
visible place for the medical staff showing the intensities of the dose rates with visual indication of
the color for the intensities of the dose rates in the medical staff. The estimated doses found by
the system were: 1.4 0.5 mSv/h trunk; 4.5 0.5 mSv/h hands; 0.8 0.5 thyroid; and 0.28 0.5 mSv/h
eyes. Work supported by CNPq, CAPES and Fundação Araucária.