Dissertação
Proposta para otimização de protocolos de exames em tomografia computadorizada, visando a redução das doses de radiação dos pacientes
Fecha
2011-08-30Registro en:
CÁS, Elias Vergílio da. PROPOSAL FOR IMPROVEMENT OF EXAMINATION PROTOCOLS
IN COMPUTED TOMOGRAPHY WITH REGARD TO THE REDUCTION OF RADIATION DOSES TO PATIENTS.. 2011. 199 f. Dissertação (Mestrado em Engenharia de Produção) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Cás, Elias Vergílio da
Institución
Resumen
The challenge for professional physicists, doctors and technicians and to identify the
limits of acceptable image quality of the procedures to minimize the radiation dose to
patients subjected. The definition of image quality should extend to matters of view of
lesions to optimize the dose of radiation. (Kalra et al, 2004, p. 620). In this paper, the
proposed optimization of the protocols provided by manufacturers of equipment for
computed tomography (CT), give yourself to the reduction of transportable cargo
(MAS) suggested by the manufacturers. The proposed new MAS, or optimized to be
found by the intersection of two curves, which correlate dose levels and noise, plotted
on the y axis, with the MAS, the x-axis Two devices were studied with computed
tomography protocols optimized. Equipment has a single section (single slice) and
the other multiple sections (multi-slice). The optimization was carried out in the protocols
correspond to the skull by larger percentages of examinations. The quality of
images of original and optimized protocols was analyzed quantitatively and qualitatively.
Quantitatively, we analyzed the relation to noise (ASD), the High Spatial Resolution
Contrast (HSRC), the spatial resolution of low contrast (SRLC) and Signal to
Noise Ratio (SNR). From a qualitative (images) analyzed the noise (phantom water),
the HSRC (phantom) and SRLC (phantom). Concurrently, we estimated the amount
of heat generated in the X-ray tube. For the protocol 1∆ original, but 250 mAs, the
CTDIVol, Exp was 33.19. For the protocol 1∆ optimized for 235 mAs, the CTDIVol, Exp
was 31.37. 2∆ for the original protocol, but in 250, the CTDIVol, Exp was 33.96. For the
protocol optimized for 235 mAs, the CTDIVol, Exp was 32.96. For the protocol 3∆ original,
but 150, the CTDIVol, Exp was 18.28. For the protocol 3∆ optimized for 143 MAS,
the CTDIVol, Exp was 16.63. For the protocol 4∆ original, but 150, the CTDIVol, Teo was
39.90. For the protocol optimized 4∆, 135 mAs, the CTDIVol, Exp was 28.29. For protocol
5∆ original, but 380, the CTDIVol, Exp was 40.97. For protocol 5∆ optimized for 367
mAs, the CTDIVol, Teo was 44.66. For protocol 6∆ original of 190 mAs, the CTDIVol, Exp
was 20.04. For protocol 6∆ optimized for 178 mAs, the CTDIVol, Exp was 18.66. The
protocols were already with low mAs, the technique used to find the optimal mAs
provided noise levels that have not harmed the image quality, there was a natural
increase in noise with decreasing mAs, however, that amount was found acceptable,
as can be seen in the images obtained.