Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT

In SPECT, noise is one of the major limitations that degrade image quality. To suppress the noisy signals in an image, digital filters are most commonly applied. However, in SPECT image recon-struction, selection of an appropriate filter and its functions has always remained a difficult task. In thi...

Full description

Bibliographic Details
Main Authors:	Sayed, Inayatullah Shah, Mohamed Nasrudin, Nor Syahirah
Format:	Article
Language:	English
Published:	Scientific Research Publishing 2016
Subjects:	QC Physics
Online Access:	http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/1/IJMPCERO_2016_BWFilter.pdf

id	iium-49979
recordtype	eprints
spelling	iium-499792016-10-12T09:55:27Z http://irep.iium.edu.my/49979/ Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT Sayed, Inayatullah Shah Mohamed Nasrudin, Nor Syahirah QC Physics In SPECT, noise is one of the major limitations that degrade image quality. To suppress the noisy signals in an image, digital filters are most commonly applied. However, in SPECT image recon-struction, selection of an appropriate filter and its functions has always remained a difficult task. In this work an attempt was made to investigate the effects of varying cut-off frequencies and in keeping the order of Butterworth filter constant on detectability and contrast of hot and cold re-gions images. A new insert simulating hot and cold regions which provides similar views in a re-constructed image was placed in the phantom’s cylindrical source tank and imaged. Tc-99m ra-dionuclide was distributed uniformly in the phantom. SPECT data were collected in a 20% energy window centered at 140 keV by a Philips ADAC Forte dual head gamma camera mounted with a LEHR collimator. Images were generated by using the filtered backprojection technique. A But-terworth filter of order 5 with cut-off frequencies 0.35 and 0.45 cycles.cm-1 was applied. Images were examined in terms of hot and cold regions, detectability and contrast. Results show that the hot and cold regions’ detectability and contrast vary with the change of cut-off frequency. With a 0.45 cycles.cm-1 cut-off frequency a significant enhancement in contrast of cold regions was achieved as compared to a 0.35 cycles.cm-1 cut-off frequency. Furthermore, the detectability of hot and cold regions improved with the use of a 0.45 cycles.cm-1 cut-off frequency. In conclusion, image quality of hot and cold regions affected in a different way with a change of cut-off frequency. Thus, care should be taken in selecting the filter cut-off frequency prior to reconstruction of images; particularly, when both types of regions are expected in the reconstructed image. Scientific Research Publishing 2016-02 Article PeerReviewed application/pdf en http://irep.iium.edu.my/49979/1/IJMPCERO_2016_BWFilter.pdf Sayed, Inayatullah Shah and Mohamed Nasrudin, Nor Syahirah (2016) Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 5 (1). pp. 100-109. ISSN 2168-5436 E-ISSN 2168-5444 http://www.scirp.org/journal/ijmpcero http://dx.doi.org/10.4236/ijmpcero.2016.51011
repository_type	Digital Repository
institution_category	Local University
institution	International Islamic University Malaysia
building	IIUM Repository
collection	Online Access
language	English
topic	QC Physics
spellingShingle	QC Physics Sayed, Inayatullah Shah Mohamed Nasrudin, Nor Syahirah Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
description	In SPECT, noise is one of the major limitations that degrade image quality. To suppress the noisy signals in an image, digital filters are most commonly applied. However, in SPECT image recon-struction, selection of an appropriate filter and its functions has always remained a difficult task. In this work an attempt was made to investigate the effects of varying cut-off frequencies and in keeping the order of Butterworth filter constant on detectability and contrast of hot and cold re-gions images. A new insert simulating hot and cold regions which provides similar views in a re-constructed image was placed in the phantom’s cylindrical source tank and imaged. Tc-99m ra-dionuclide was distributed uniformly in the phantom. SPECT data were collected in a 20% energy window centered at 140 keV by a Philips ADAC Forte dual head gamma camera mounted with a LEHR collimator. Images were generated by using the filtered backprojection technique. A But-terworth filter of order 5 with cut-off frequencies 0.35 and 0.45 cycles.cm-1 was applied. Images were examined in terms of hot and cold regions, detectability and contrast. Results show that the hot and cold regions’ detectability and contrast vary with the change of cut-off frequency. With a 0.45 cycles.cm-1 cut-off frequency a significant enhancement in contrast of cold regions was achieved as compared to a 0.35 cycles.cm-1 cut-off frequency. Furthermore, the detectability of hot and cold regions improved with the use of a 0.45 cycles.cm-1 cut-off frequency. In conclusion, image quality of hot and cold regions affected in a different way with a change of cut-off frequency. Thus, care should be taken in selecting the filter cut-off frequency prior to reconstruction of images; particularly, when both types of regions are expected in the reconstructed image.
format	Article
author	Sayed, Inayatullah Shah Mohamed Nasrudin, Nor Syahirah
author_facet	Sayed, Inayatullah Shah Mohamed Nasrudin, Nor Syahirah
author_sort	Sayed, Inayatullah Shah
title	Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
title_short	Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
title_full	Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
title_fullStr	Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
title_full_unstemmed	Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT
title_sort	effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in tc-99m spect
publisher	Scientific Research Publishing
publishDate	2016
url	http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/ http://irep.iium.edu.my/49979/1/IJMPCERO_2016_BWFilter.pdf
first_indexed	2023-09-18T21:10:37Z
last_indexed	2023-09-18T21:10:37Z
_version_	1777411227893366784

Effect of cut-off frequency of butterworth filter on detectability and contrast of hot and cold regions in Tc-99m SPECT

Similar Items