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541 ST 6.3 – Protección radiológica del público y el ambiente
CALCULATION TECHNIQUE FOR THE SECONDARY SHIELDING AGAINST
X-RAY OF MEGAVOLTAGE
da Silva Borges, Diogo*; Lava, Deise Diana; Fernandes da Silva, Lucinda;
Werneck Affonso, Renato Raoni; Moreira, Maria de Lourdes;
Ferreira Guimarães, Antonio Cesar
Instituto de Engenharia Nuclear. Brazil.
* Responsible author, email: diogofisica@ymail.com
With the use of high power beams, it becomes necessary to realize considerations of the
production of secondary beams in rooms that containing X-ray apparatus of megavoltage. The
residual Radiation originate from the interaction of the primary beam with the patient can
interfere in the dose limits established in the CNEN-NN-3.01 published in September 2011.
Thus, this paper presents the development of a algorithm capable of calculate the thickness of
secondary barriers against scattering beams and leakage. The analysis of secondary beam
requires consideration of the scattering angle, as well as factors normally used to shield medical
facilities that use radiographic techniques. The code was validated by comparison with a case
example provided by the NCRP-151 Report. In it are given calculations for the determining the
secondary barrier for small angles and for the technique of Radiotherapy intensity modulated
(IMRT). The results are consistent with those provided by the report, making the code can be
used as a practical tool for the determination of an efficient shielding against X-ray beam of
megavoltage.