![]() ![]() In this context, different types of filters, such as high-pass, low-pass, and band-pass, are used. Compared to radiology, noise is more common in nuclear medicine imaging which can be reduced by using digital filters. In clinical applications, image noise tends to limit the diagnostic accuracy and increases the difficulty in providing high quality medical services to patients. In SPECT, image noise is an important factor may degrade the image quality. Effects of both filters on the quality of hot and cold region images varied with the change in cutoff frequency. Overall, the Butterworth filter under investigation provided superior results than the Hamming filter. ![]() However, with the Butterworth filter, the decrease in SNR for both types of regions with the increase in cutoff frequency as compared to the Hamming filter was obtained. In addition, higher contrast values were recorded, as compared to the Hamming filter. The findings of our study indicate that the Butterworth filter was able to expose more hot and cold regions in reconstructed images. Images of hot and cold regions were analyzed in terms of detectability, contrast, and signal-to-noise ratio (SNR). Various cutoff frequency values, namely, 0.35, 0.40, 0.45, and 0.50 cycles/cm, were selected for both filters, whereas for the Butterworth filter, the order was set at 7. Images were reconstructed by the FBP method. Furthermore, a symmetrical energy window (20%) centered at 140 keV was adjusted. A Technetium-99m radioactive solution was homogenously mixed into the phantom. ![]() SPECT data were acquired by scanning a phantom with an insert composed of hot and cold regions. A low-energy, high-resolution collimator was installed on the gamma camera. A Philips ADAC forte gamma camera was used. In this study, the effects on the quality of reconstructed images of the Butterworth filter were compared with the ones of the Hamming filter. With this technique, different types of reconstruction filters are used, such as the Butterworth and the Hamming. Filtered back projection (FBP) is the most popular technique for image reconstruction in SPECT. Adverse effects on image quality arise if an improper filter is selected. In single photon emission computed tomography (SPECT) imaging, the choice of a suitable filter and its parameters for noise reduction purposes is a big challenge. ![]()
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January 2023
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