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

Counting statistics (kilocounts per second (kcps)) for the 30 min acquisition with 2 bed positions for Day 0, 3, 5 and 7 measurement time points during 1 week and an empty phantom measurement.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110401-g001: Counting statistics (kilocounts per second (kcps)) for the 30 min acquisition with 2 bed positions for Day 0, 3, 5 and 7 measurement time points during 1 week and an empty phantom measurement.

Mentions: Total prompts, randoms and the net trues for the 30 min acquisition at the four time points are shown in Figure 1. Total prompts and random coincidences have an offset due to the contributions from the single photons from 176Lu. The net true coincidences fall along a straight line with a slope of (189.4±1.5) kcps/GBq, y-intercept of (6.8±2.5) kcps and R2 = 0.9998. The amount of inherent activity in the detectors due to the gamma emissions from 176Lu was estimated from the background trues to be approximately 2.77 MBq. The sensitivity of the system for 90Y measurements based on its positron emission was calculated to be (3.63±0.02) cps/kBq.


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)

Counting statistics (kilocounts per second (kcps)) for the 30 min acquisition with 2 bed positions for Day 0, 3, 5 and 7 measurement time points during 1 week and an empty phantom measurement.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110401-g001: Counting statistics (kilocounts per second (kcps)) for the 30 min acquisition with 2 bed positions for Day 0, 3, 5 and 7 measurement time points during 1 week and an empty phantom measurement.
Mentions: Total prompts, randoms and the net trues for the 30 min acquisition at the four time points are shown in Figure 1. Total prompts and random coincidences have an offset due to the contributions from the single photons from 176Lu. The net true coincidences fall along a straight line with a slope of (189.4±1.5) kcps/GBq, y-intercept of (6.8±2.5) kcps and R2 = 0.9998. The amount of inherent activity in the detectors due to the gamma emissions from 176Lu was estimated from the background trues to be approximately 2.77 MBq. The sensitivity of the system for 90Y measurements based on its positron emission was calculated to be (3.63±0.02) cps/kBq.

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