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Relationship between the optimum cut off frequency for Butterworth filter and lung-heart ratio in 99mTc myocardial SPECT
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M.N. Salihin Yusoff   , A. Zakaria |
| , mnsalihin@gmail.com |
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Abstract: (15195 Views) |
| Background: We investigated whether the lungheart
ratio parameter (LHR) can be used to identify
the optimum cut off frequency for Butterworth filter in
99mTc myocardial SPECT imaging. Materials and
Methods: This study involved a cardiac phantom
system consisting of cardiac insert in which 1.10 cm
cold defect was inserted into its myocardium wall and
filled with 4.0 μCi/ml (0.148 MBq/ml) 99mTc
concentration. The cardiac insert was then put into a
cylindrical tank which filled with six different 99mTc
concentrations as background. Thus, six target background
concentrations ratios (T/B) were carried
out. The LHR was determined for every SPECT raw
image obtained corresponding to each T/B. Then,
130 different combinations of filter parameters from
Butterworth filter were utilized to reconstruct each
SPECT raw image. The determination of count in
myocardium, background, and defect regions of
interest (ROI) were performed for every reconstructed
image. All the count values were then used to calculate
contrast, signal-to-noise ratio (SNR), and defect
size. Each criterion was graded (1 to 100) and then
summed together to obtain total grade. The optimum
cut off frequency for each LHR was determined from
the total grade. The relation between optimum cut off
frequency for Butterworth filter and LHR was
established using linear regression. Results: There
were good relationship between the optimum Butterworth
cut off frequency and LHR (R2 = 0.864, p <
0.01). The optimal cut off frequency correspond to
the change in LHR can be expressed by the equation:
Optimum cut off frequency = 0.715*LHR + 0.227.
Conclusion: This study suggests that the optimum cut
off frequency for Butterworth filter should be determined
by referring to LHR in each patient study. Iran.
J. Radiat. Res., 2010 8 (1): 17-24 |
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| Keywords: 99mTc myocardial SPECT, filtering, lungheart ratio. |
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Full-Text [PDF 508 kb]
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Type of Study: Original Research |
Subject:
Radiation Biology
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