Limits...
Quantitative and qualitative assessment of Yttrium-90 PET/CT imaging.

Attarwala AA, Molina-Duran F, Büsing KA, Schönberg SO, Bailey DL, Willowson K, Glatting G - PLoS ONE (2014)

Bottom Line: For the smaller diameter spheres, the PSF algorithm with TOF and single bed acquisition provided a comparatively better activity recovery.Quantification of Y-90 using Biograph mCT PET/CT is possible with a reasonable accuracy, the limitations being the size of the lesion and the activity concentration present.At this stage, based on our study, it seems advantageous to use different protocols depending on the size of the lesion.

View Article: PubMed Central - PubMed

Affiliation: Medical Radiation Physics/Radiation Protection, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.

ABSTRACT
Yttrium-90 is known to have a low positron emission decay of 32 ppm that may allow for personalized dosimetry of liver cancer therapy with (90)Y labeled microspheres. The aim of this work was to image and quantify (90)Y so that accurate predictions of the absorbed dose can be made. The measurements were performed within the QUEST study (University of Sydney, and Sirtex Medical, Australia). A NEMA IEC body phantom containing 6 fillable spheres (10-37 mm ∅) was used to measure the 90Y distribution with a Biograph mCT PET/CT (Siemens, Erlangen, Germany) with time-of-flight (TOF) acquisition. A sphere to background ratio of 8:1, with a total (90)Y activity of 3 GBq was used. Measurements were performed for one week (0, 3, 5 and 7 d). he acquisition protocol consisted of 30 min-2 bed positions and 120 min-single bed position. Images were reconstructed with 3D ordered subset expectation maximization (OSEM) and point spread function (PSF) for iteration numbers of 1-12 with 21 (TOF) and 24 (non-TOF) subsets and CT based attenuation and scatter correction. Convergence of algorithms and activity recovery was assessed based on regions-of-interest (ROI) analysis of the background (100 voxels), spheres (4 voxels) and the central low density insert (25 voxels). For the largest sphere, the recovery coefficient (RC) values for the 30 min -2-bed position, 30 min-single bed and 120 min-single bed were 1.12 ± 0.20, 1.14 ± 0.13, 0.97 ± 0.07 respectively. For the smaller diameter spheres, the PSF algorithm with TOF and single bed acquisition provided a comparatively better activity recovery. Quantification of Y-90 using Biograph mCT PET/CT is possible with a reasonable accuracy, the limitations being the size of the lesion and the activity concentration present. At this stage, based on our study, it seems advantageous to use different protocols depending on the size of the lesion.

Show MeSH

Related in: MedlinePlus

Convergence of the hot spheres (central 4 voxels in each sphere), with the PSF TOF algorithm for the (A) 30 min-2 bed position acquisition and (B) 120 min-one bed position acquisition, reconstruction parameters: 1–12 iterations with 21 (TOF) subsets, 5 mm Gaussian filtering and an image matrix of 400.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4219690&req=5

pone-0110401-g004: Convergence of the hot spheres (central 4 voxels in each sphere), with the PSF TOF algorithm for the (A) 30 min-2 bed position acquisition and (B) 120 min-one bed position acquisition, reconstruction parameters: 1–12 iterations with 21 (TOF) subsets, 5 mm Gaussian filtering and an image matrix of 400.

Mentions: The figures 3 and 4 show the convergence of the images based on ROI analyses. For the PSF TOF algorithm and the 30 min acquisition, the background and lung reconstructed activity concentration change about 9% and 15%, respectively, from the first to the third iteration and 37% and 10%, respectively, from the first to the twelfth iteration (Fig.3A). For the 120 min acquisition, corresponding changes were 1% and 52%, and 2% and 61%, respectively (Fig.3B). The reconstructed activity concentration in the 37 mm and 28 mm spheres change about 3% and 7%, respectively, from the first to the third iteration and 2% and 10%, respectively, from the first to the twelfth iteration, for the 30 min acquisition (Fig.4A). For the 120 min acquisition, corresponding changes were 22% and 5%, and 22% and 8%, respectively (Fig.4B).


Quantitative and qualitative assessment of Yttrium-90 PET/CT imaging.

Attarwala AA, Molina-Duran F, Büsing KA, Schönberg SO, Bailey DL, Willowson K, Glatting G - PLoS ONE (2014)

Convergence of the hot spheres (central 4 voxels in each sphere), with the PSF TOF algorithm for the (A) 30 min-2 bed position acquisition and (B) 120 min-one bed position acquisition, reconstruction parameters: 1–12 iterations with 21 (TOF) subsets, 5 mm Gaussian filtering and an image matrix of 400.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219690&req=5

pone-0110401-g004: Convergence of the hot spheres (central 4 voxels in each sphere), with the PSF TOF algorithm for the (A) 30 min-2 bed position acquisition and (B) 120 min-one bed position acquisition, reconstruction parameters: 1–12 iterations with 21 (TOF) subsets, 5 mm Gaussian filtering and an image matrix of 400.
Mentions: The figures 3 and 4 show the convergence of the images based on ROI analyses. For the PSF TOF algorithm and the 30 min acquisition, the background and lung reconstructed activity concentration change about 9% and 15%, respectively, from the first to the third iteration and 37% and 10%, respectively, from the first to the twelfth iteration (Fig.3A). For the 120 min acquisition, corresponding changes were 1% and 52%, and 2% and 61%, respectively (Fig.3B). The reconstructed activity concentration in the 37 mm and 28 mm spheres change about 3% and 7%, respectively, from the first to the third iteration and 2% and 10%, respectively, from the first to the twelfth iteration, for the 30 min acquisition (Fig.4A). For the 120 min acquisition, corresponding changes were 22% and 5%, and 22% and 8%, respectively (Fig.4B).

Bottom Line: For the smaller diameter spheres, the PSF algorithm with TOF and single bed acquisition provided a comparatively better activity recovery.Quantification of Y-90 using Biograph mCT PET/CT is possible with a reasonable accuracy, the limitations being the size of the lesion and the activity concentration present.At this stage, based on our study, it seems advantageous to use different protocols depending on the size of the lesion.

View Article: PubMed Central - PubMed

Affiliation: Medical Radiation Physics/Radiation Protection, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.

ABSTRACT
Yttrium-90 is known to have a low positron emission decay of 32 ppm that may allow for personalized dosimetry of liver cancer therapy with (90)Y labeled microspheres. The aim of this work was to image and quantify (90)Y so that accurate predictions of the absorbed dose can be made. The measurements were performed within the QUEST study (University of Sydney, and Sirtex Medical, Australia). A NEMA IEC body phantom containing 6 fillable spheres (10-37 mm ∅) was used to measure the 90Y distribution with a Biograph mCT PET/CT (Siemens, Erlangen, Germany) with time-of-flight (TOF) acquisition. A sphere to background ratio of 8:1, with a total (90)Y activity of 3 GBq was used. Measurements were performed for one week (0, 3, 5 and 7 d). he acquisition protocol consisted of 30 min-2 bed positions and 120 min-single bed position. Images were reconstructed with 3D ordered subset expectation maximization (OSEM) and point spread function (PSF) for iteration numbers of 1-12 with 21 (TOF) and 24 (non-TOF) subsets and CT based attenuation and scatter correction. Convergence of algorithms and activity recovery was assessed based on regions-of-interest (ROI) analysis of the background (100 voxels), spheres (4 voxels) and the central low density insert (25 voxels). For the largest sphere, the recovery coefficient (RC) values for the 30 min -2-bed position, 30 min-single bed and 120 min-single bed were 1.12 ± 0.20, 1.14 ± 0.13, 0.97 ± 0.07 respectively. For the smaller diameter spheres, the PSF algorithm with TOF and single bed acquisition provided a comparatively better activity recovery. Quantification of Y-90 using Biograph mCT PET/CT is possible with a reasonable accuracy, the limitations being the size of the lesion and the activity concentration present. At this stage, based on our study, it seems advantageous to use different protocols depending on the size of the lesion.

Show MeSH
Related in: MedlinePlus