Physica Medica: European Journal of Medical Physics - Volume 32 - Supplement 1 - February 2016

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fix the maximum value of contamination accepted. In this work we propose
a procedure to assess the radionuclide purity of [18F]FDG samples for routine
quality controls by using gamma ray spectrometry.
Materials and Methods: 18-fluorine is produced through proton irradia-
tion of a small volume of 18-oxygen enriched water in a 9 MeV cyclotron
and then transferred to a synthesis module for the production of [18F]FDG
to be injected.
Gamma rays emitted by samples of the radiopharmaceutical are acquired
by an HPGe detector shielded by lead from atmospheric background ra-
diation; gamma spectra are analyzed with a software that associates the
peaks in the spectrum to radionuclides included in a library user defined
and uses efficiency and energy calibrations to calculate the activities.
Minimum Detectable Activities (MDA) for the nuclides in the library are
also provided.
Results: Base on literature evidence, a library was developed taking into
account all possible contaminants in [18F]FDG routine production of our
center with a mean life compatible with timing involved in the detection.
Spectrum acquisition duration was evaluated considering the minimum con-
centration to be detected for a long-life contaminant. Cross verifications
were also used to identify the origin of the peaks in the spectra. Radionu-
clide purity was then evaluated as the ratio between the sum of detected
activities (related to release time) and the total activity actually mea-
sured at the release time. The sum of MDAs and detected activities was
finally used as an estimate of the maximum activity due to all contaminants.
Conclusions: The procedure can be used in the routine for radionuclide
purity assessment of FDG and can be extended to other radiopharmaceu-
tical. The proposed method supplies instruments to verify the reliability
of obtained results.
C.384
DIFFERENT POLAR-MAP PATTERNS USING THE NOVEL TECHNOLOGY FOR
MYOCARDIAL PERFUSION IMAGING (MPI)
C. Scabbio O. Zoccarat C. Marcass D. Lizio L. Leva G. Lucignani
A. Savi R. Matheoud M. Lecchi M. Brambill a Department of Health
Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital,
Milan, Italy; b Unit of Nuclear Medicine and Department of Cardiology, S.
Maugeri Foundation, IRCCS, Scientific Institute of Veruno, Veruno (NO), Italy;
c Departments of Medical Physics and Nuclear Medicine, University Hospital
Maggiore della Carità, Novara, Italy; d Unit of Nuclear Medicine, San Raffaele
Hospital of Milan (IRCCS), Milan, Italy
Introduction: Iterative algorithms with resolution recovery (IRRs), inno-
vative collimators and dedicated cameras with CZT detectors are now
available in MPI. Our aim was to evaluate the impact of this novel tech-
nology on the uniformity of normal myocardial uptake in the polar-map
representation, over a wide range of acquired count statistics, and with and
without the attenuation and scatter corrections (SCAC).
Materials and Methods: A phantom study was performed and consid-
ered twenty-one scanner/software combinations and reconstruction
methods: 4 conventional gamma-cameras with filtered-back-projection (FBP)
or IRR, with or without AC; a Symbia–IQ (Siemens) and a D530c (General
Electric), with or without AC; and a D-SPECT (Spectrum Dynamics). Dif-
ferent count statistics were considered up to a quarter of the reference
(6 × 106 counts in the left-ventricular) for the conventional gamma-
cameras and up to one-twelfth for the advanced scanners. Using the 17-
segment polar-map, the regional and vascular segmental uptakes, the
coefficient of variation (COV) among the segmental uptakes and the anterior/
inferior (ANT/INF) ratio were calculated.
Results: The normal polar-map pattern did not depend on the selected count
statistics. Reconstruction method and scanner/software combination
(p < 0.0001) were all main effects with a statistically significant impact on
normal myocardial uptake. A significant increase in the segmental uptakes
was found from IRR to IRR + SCAC (78.0 ± 13.5% vs 86.1 ± 9.4%; p < 0.0001).
COV was significantly lower for D-SPECT (10.1 ± 0.5%) and after SCAC both
for conventional (9.9 ± 3.0%) and advanced systems (8.9 ± 1.7%). The ANT/
INF ratio was above 1 for IRR (1.12 ± 0.07), while fell below 1 for IRR + SCAC
(0.97 ± 0.05).
Conclusions: Different normal polar-map patterns were found in MPI.
However, for the same scanner/software combination and reconstruction
method, low-dose or short-time studies could be performed using the same
normality database of the reference protocol.
C.385
CHARACTERIZATION OF A PET SCANNER FOR IMAGING WITH 68GA
G. Serreli O. Ortenzi L. Ruffin C. Ghett a Servizio di Fisica Sanitaria,
AOU Parma, Parma, Italy; b S.C. Medicina Nucleare, AOU Parma, Parma, Italy
Aim: The aim of this study is the characterization of the new PET scanner
GE Discovery IQ for imaging with 68Ga.
68Ga radionuclide has great interest in PET imaging because somatosta-
tin receptor-based imaging with 68Ga-labeled radioligands is considered
superior in detection of NET primary tumors and metastases on the other
standard imaging techniques. Moreover it is possible to provide 68Ga, with
a 68Ge/68Ga generator, on demand in sites without a cyclotron.
Methods and Materials: NEMA NU-2-2007 tests were performed with 68Ga
for Discovery IQ to measure spatial resolution, sensitivity and PET image
quality (IQ).
IQ test was made with NEMA IEC Body phantom filling the fourth small-
est spheres. The hot-spheres/background concentration ratio was 4:1. Data
were corrected for attenuation, scatter, and random coincidences, and the
images were reconstructed with VPHD and the new QC algorithm.
We have evaluated the correctness of SUV calculation, acquiring a 68Ga
uniformity phantom twice: first, acquisition with the 68Ga WCC calibra-
tion and, second, using 18F WCC calibration.
Results: The spatial resolution, respectively radial, tangential, axial at 1 cm
and at 10 cm, was 3.82, 4.67, 4.91 mm and 5.89, 4.77, 5.03 mm. The results
using 18F were 3.8, 4.7, 4.81, 5.81, 4.24, and 5.79 mm.
Sensitivity at the center and at 10 cm off-center was 26.70 and 28.10 cps/
kBq. 18F results were 22.4 and 20 cps/kBq.
Contrast recovery coefficients (CRC) for spheres were 37.6% (1.00 mm),
43.90% (1.30 mm), 62.20% (1.70 mm), 69.00% (2.20 mm), 70.80% (2.80 mm)
and 74.40% (3.70 mm). 18F results were 36.50%, 58.40%, 68.20%, 67.60%,
72.40% and 76.10%.
RE over the lung insert was 18.4% with 68Ga and 17.60% with 18F.
Furthermore it was verified that the evaluation of SUV is correct within
the 10% using 18F WCC calibration even for 68Ga exams.
Conclusions: The performances of Discovery IQ with 68Ga are fully com-
parable to those with the 18F. In addition, in clinical routine it is not
necessary to use a dedicated 68Ga WCC calibration.
C.386
EFFECTIVE DOSE ESTIMATE IN PET-CT EXAMINATIONS
M. Sireus O. Ortenzi F. Paller G. Serreli L. Ruffini C. Ghetti
a Università degli Studi di Cagliari, Cagliari, Italy; b Servizio di Fisica Sanitaria,
AOU Parma, Parma, Italy; c S.C. Medicina Nucleare, AOU Parma, Parma, Italy
Introduction: The recent Directive EURATOM 2013/59, which will be imple-
mented by member states within February 2018, introduces the need to
communicate dosimetric data to the patient. The purpose of this study is
to assess the CTDIvol, DLP and administered activity in PET-CT examina-
tions; we have also evaluated the effective dose for the whole procedure
in order to verify that also in hybrid imaging the ALARA principle is
respected.
Materials and Methods: The study was performed in the Nuclear Medi-
cine Dept of Parma Hospital using a GE Discovery-ST PET-CT. We
retrospectively evaluated the mean value of Effective Dose for a sample of
40 patients (20 men and 20 women) who underwent F-18 Total Body ex-
amination. Dosimetric data (CTDIvol, DLP and injected activity) were
manually extrapolated from DICOM header. We calculated CT contribu-
tion to the Effective Dose using the ImPACT CT Patient Dosimetry Calculator
and PET contribution to the Effective Dose using activity/dose conversion
coefficients published in the EJNMMI Physics (2014) using different values
for men and women.
Results: The mean CTDIvol and administered activity were 2.1 mGy and
3.7 MBq/kg respectively. The mean Effective Dose was 7.8 ± 1.5 mSv for men
e113 Abstracts/Physica Medica 32 (2016) e97–e115