Evaluation of transmission source collimation for SPECT attenuation compensation

Tornai, Martin P.; Bowsher, J.E.; Stone, C.D.; Gilland, D.R.; Jaszczak, R.J.; Enos, G.

doi:10.1109/nssmic.1999.842810

Cited by 2 publications

(4 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Substituting (13) into (12), we obtained a separable surrogate function (14) Minimizing and enforcing the nonnegativity constraint, we obtained the update as (15) where the operator for , and zero otherwise. From (5), we have the gradient (16) To calculate the gradient as in (16), one should perform one forward-blur in and one back-blur in . Taking into account only for rays within the same projection view, these blurring steps are performed frame-by-frame within projection/backprojection and do not affect severely reconstruction time.…”

Section: In Transmission Imaging the Measurement Model Ismentioning

confidence: 99%

“…To adapt our method to the OSTR algorithm, we replaced the sum over in (16) with the sum over subsets of the rays, and approximated with , which is independent of the iteration number thus achieving a fast implementation [24]. From (13), we have (17) Since the blur caused by the finite detector resolution is small, we approximated , where if , otherwise…”

Section: In Transmission Imaging the Measurement Model Ismentioning

confidence: 99%

“…[7]- [14]. The finite intrinsic spatial Manuscript resolution of the camera and nonideal photon collimation cause an imprecision in the detected location and assumed origin of the transmission photons, which results in the blurred attenuation maps [15], [16]. Herein, when we speak of system resolution we will be referring to the combination of the intrinsic resolution of the NaI(Tl) camera, and geometric resolution provided by collimation.…”

Section: Introductionmentioning

confidence: 99%

“…For line-source [7], [15] or scanning line-source [12], [19] transmission systems, the spatial resolution can be different between the transverse and axial directions, since in one direction the position of the source is well-defined or the source is well-collimated via electronic collimation and in the other direction it should be treated as the extended source [20] since typically no added source collimation is provided along the line. As the finite resolution of the imaging system causes image degradation in emission reconstruction, it also causes degradation of attenuation maps obtained from transmission reconstructions [15], [16].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT

Feng

Fessler

King

2006

IEEE Trans. Med. Imaging

View full text Add to dashboard Cite

In order to reconstruct attenuation maps with improved spatial resolution and quantitative accuracy, we developed an approximate method of incorporating system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission reconstruction. Our method approximately models the blur caused by the finite intrinsic detector resolution, the nonideal source collimation and detector collimation. We derived the formulation using the optimization transfer principle as in the derivation of the OSTR algorithm. The formulation includes one forward-blur step and one back-blur step, which do not severely slow down reconstruction. The formulation could be applicable to various transmission geometries, such as point-source, line-source, and sheet-source systems. Through computer simulations of the MCAT phantom and transmission measurements of the air-filled Data Spectrum Deluxe single photo emission computed tomography (SPECT) Phantom on a system which employed a cone-beam geometry and a system which employed a scanning-line-source geometry, we showed that incorporation of RC increased spatial resolution and improved the quantitative accuracy of reconstruction. In simulation studies, attenuation maps reconstructed with RC correction improved the quantitative accuracy of emission reconstruction.

show abstract

Section: In Transmission Imaging the Measurement Model Ismentioning

confidence: 99%

Section: In Transmission Imaging the Measurement Model Ismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT

Feng

Fessler

King

2006

IEEE Trans. Med. Imaging

View full text Add to dashboard Cite

show abstract

Modeling the axial extension of a transmission line source within iterative reconstruction via multiple transmission sources

Bowsher

Tornai

Peter

et al. 2002

IEEE Trans. Med. Imaging

View full text Add to dashboard Cite

Reconstruction algorithms for transmission tomography have generally assumed that the photons reaching a particular detector bin at a particular angle originate from a single point source. In this paper, we highlight several cases of extended transmission sources, in which it may be useful to approach the estimation of attenuation coefficients as a problem involving multiple transmission point sources. Examined in detail is the case of a fixed transmission line source with a fan-beam collimator. This geometry can result in attenuation images that have significant axial blur. Herein it is also shown, empirically, that extended transmission sources can result in biased estimates of the average attenuation, and an explanation is proposed. The finite axial resolution of the transmission line source configuration is modeled within iterative reconstruction using an expectation-maximization algorithm that was previously derived for estimating attenuation coefficients from single photon emission computed tomography (SPECT) emission data. The same algorithm is applicable to both problems because both can be thought of as involving multiple transmission sources. It is shown that modeling axial blur within reconstruction removes the bias in the average estimated attenuation and substantially improves the axial resolution of attenuation images.

show abstract

Evaluation of transmission source collimation for SPECT attenuation compensation

Cited by 2 publications

References 6 publications

Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT

Incorporation of system resolution compensation (RC) in the ordered-subset transmission (OSTR) algorithm for transmission imaging in SPECT

Modeling the axial extension of a transmission line source within iterative reconstruction via multiple transmission sources

Contact Info

Product

Resources

About