TY  - JOUR
A1  - Lassmann, Michael
A1  - Preylowski, Veronika
A1  - Schlögl, Susanne
A1  - Schoenahl, Frédéric
A1  - Jörg, Gerhard
A1  - Samnick, Samuel
A1  - Buck, Andreas K.
T1  - Is the Image Quality of I-124-PET Impaired by an Automatic Correction of Prompt Gammas?
JF  - PLoS ONE
N2  - Objectives

The aim of this study is to evaluate the quality of I-124 PET images with and without prompt gamma compensation (PGC) by comparing the recovery coefficients (RC), the signal to noise ratios (SNR) and the contrast to F-18 and Ga-68. Furthermore, the influence of the PGC on the quantification and image quality is evaluated.

Methods

For measuring the image quality the NEMA NU2-2001 PET/SPECT-Phantom was used containing 6 spheres with a diameter between 10 mm and 37 mm placed in water with different levels of background activity. Each sphere was filled with the same activity concentration measured by an independently cross-calibrated dose calibrator. The “hot” sources were acquired with a full 3D PET/CT (Biograph mCT®, Siemens Medical USA). Acquisition times were 2 min for F-18 and Ga-68, and 10 min for I-124. For reconstruction an OSEM algorithm was applied. For I-124 the images were reconstructed with and without PGC. For the calculation of the RCs the activity concentrations in each sphere were determined; in addition, the influence of the background correction was studied.

Results

The RCs of Ga-68 are the smallest (79%). I-124 reaches similar RCs (87% with PGC, 84% without PGC) as F-18 (84%). showing that the quantification of I-124 images is similar to F-18 and slightly better than Ga-68. With background activity the contrast of the I-124 PGC images is similar to Ga-68 and F-18 scans. There was lower background activity in the I-124 images without PGC, which probably originates from an overcorrection of the scatter contribution. Consequently, the contrast without PGC was much higher than with PGC. As a consequence PGC should be used for I-124.

Conclusions

For I-124 there is only a slight influence on the quantification depending on the use of the PGC. However, there are considerable differences with respect to I-124 image quality.
KW  - cancer treatment
KW  - health care
KW  - isotopes
KW  - photons
KW  - positron emission tomography
KW  - signal to noise ratio
KW  - super ultraviolet
KW  - thyroid carcinomas
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96863
ER  - 
TY  - JOUR
A1  - Wevrett, Jill
A1  - Fenwick, Andrew
A1  - Scuffham, James
A1  - Johansson, Lena
A1  - Gear, Jonathan
A1  - Schlögl, Susanne
A1  - Segbers, Marcel
A1  - Sjögreen-Gleisner, Katarina
A1  - Solný, Pavel
A1  - Lassmann, Michael
A1  - Tipping, Jill
A1  - Nisbet, Andrew
T1  - Inter-comparison of quantitative imaging of lutetium-177 (\(^{177}\)Lu) in European hospitals
JF  - EJNMMI Physics
N2  - Background
This inter-comparison exercise was performed to demonstrate the variability of quantitative SPECT/CT imaging for lutetium-177 (\(^{177}\)Lu) in current clinical practice. Our aim was to assess the feasibility of using international inter-comparison exercises as a means to ensure consistency between clinical sites whilst enabling the sites to use their own choice of quantitative imaging protocols, specific to their systems.

Dual-compartment concentric spherical sources of accurately known activity concentrations were prepared and sent to seven European clinical sites. The site staff were not aware of the true volumes or activity within the sources—they performed SPECT/CT imaging of the source, positioned within a water-filled phantom, using their own choice of parameters and reported their estimate of the activities within the source.

Results
The volumes reported by the participants for the inner section of the source were all within 29% of the true value and within 60% of the true value for the outer section. The activities reported by the participants for the inner section of the source were all within 20% of the true value, whilst those reported for the outer section were up to 83% different to the true value.

Conclusions
A variety of calibration and segmentation methods were used by the participants for this exercise which demonstrated the variability of quantitative imaging across clinical sites. This paper presents a method to assess consistency between sites using different calibration and segmentation methods.
KW  - Lutetium
KW  - Lu-177
KW  - SPECT/CT
KW  - quantitative imaging
KW  - PRRT
KW  - molecular radiotherapy
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233658
VL  - 5
ER  -