| 1. |
- Hademenos, George J, et al.
(författare)
-
A Monte Carlo Investigation of the Dual Photopeak Window Scatter Correction Method
- 1993
-
Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 40:2, s. 179-185
-
Tidskriftsartikel (refereegranskat)abstract
- Results from a Monte Carlo investigation of the dual photopeak window (DPW) scatter correction method are presented for point and extended sources of Tc-99m in both homogeneous and nonhomogeneous attenuating media. The DPW method uses the ratio of counts in two nonoverlapping energy windows within the photopeak region as input to a regression relation. A pixel-by-pixel estimate of the scatter in the summed windows is obtained and subtracted to yield an estimate of the primary. An approximate tenfold decrease in the scatter fraction and an excellent agreement with the shape of the true scatter distribution were observed.
|
|
| 2. |
- Hademenos, George J, et al.
(författare)
-
A Scatter Correction Method for 201-Tl images: A Monte Carlo Investigation
- 1993
-
Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 40:4, s. 1179-1186
-
Tidskriftsartikel (refereegranskat)abstract
- Results from the application of a modified dual photopeak window scatter correction method to Monte Carlo simulated Tl-201 emission images are presented. In the Monte Carlo investigation, individual simulations are performed for six radiation emissions of Tl-201. For each emission, point sources of Tl-201 are imaged at various locations in a water-filled elliptical tub phantom using three energy windows. The DPW method is applied to each point source image to estimate the scatter distribution. For point source images in both homogeneous and nonhomogeneous attenuating media, the application of this modified version of DPW results in an approximately sixfold reduction in the scatter fraction and an excellent agreement of the shape of the tails between the estimated scatter distribution and the Monte Carlo-simulated truth. This method is also applied to two views of an extended cardiac distribution within an anthropomorphic phantom, again resulting in at least a sixfold improvement between the scatter estimate and the Monte Carlo-simulated true scatter.
|
|
| 3. |
- Hademenos, George J, et al.
(författare)
-
The Influence of Phantom Size, Shape, and Density, and Collimator Selection on the Dual Photopeak Scatter Correction Method
- 1994
-
Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 41:1-2, s. 364-368
-
Tidskriftsartikel (refereegranskat)abstract
- Results from a Monte Carlo investigation are presented for the application of the dual photopeak window (DPW) scatter correction method to phantom geometries of varying shapes, sizes, and densities as well as to several collimators. A Monte Carlo program was used to simulate a Tc-99m point source at locations of 0.5 cm from the phantom surface, at the center, 0.5 cm from the bottom, and 4/5 the distance lateral from the center for each case of variation. DPW was then used to correct for scatter using a regression relation determined for a 30.5 cm×23.0 cm water-filled elliptical tub phantom using an ultrahigh resolution collimator. The application of DPW in all cases accounted for an approximate twelve-fold reduction in scatter fraction with an excellent agreement between the true scatter and scatter estimate distributions both at the tails and under the peak of the point spread functions.
|
|
| 4. |
- Ljungberg, Michael, et al.
(författare)
-
Comparison of four scatter correction methods using Monte Carlo simulated source distributions
- 1994
-
Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 35:1, s. 143-151
-
Tidskriftsartikel (refereegranskat)abstract
- Scatter correction in SPECT is important for improving image quality, boundary detection and the quantification of activity in different regions. This paper presents a comparison of four scatter correction methods, three using more than one energy window and one convolution-subtraction correction method using spatial variant scatter line-spread functions. METHODS: The comparison is based on Monte Carlo simulated data for point sources on- and off-axis, hot and cold spheres of different diameters, and a clinically realistic source distribution simulating brain imaging. All studies were made for a uniform cylindrical water phantom. Since the nature of the detected photon is known with Monte Carlo simulation, separate images of primary and scattered photons can be recorded. These can then be compared with estimated scatter and primary images obtained from the different scatter correction methods. The criteria for comparison were the normalized mean square error, scatter fraction, % recovery and image contrast. RESULTS: All correction methods significantly improved image quality and quantification compared to those obtained with no correction. Quantitatively, no single method was observed to be the best by all criteria for all the source distributions. Three of the methods were observed to perform the best by at least one of the criteria for one of the source distributions. For brain imaging, the differences between all the methods were much less than the difference between them and no correction at all. CONCLUSION: It is concluded that performing scatter correction is essential for accurate quantification, and that all four methods yield a good, but not perfect, scatter correction. Since it is hard to distinguish the methods consistently in terms of their performance, it may be that the choice should be made on the basis of ease of implementation.
|
|
