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

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C.373
A STUDY OF MYOCARDIAL TOMOSCINTIGRAPHY BY SEMI-QUANTITATIVE
ANALYSIS
L. Pagan E. Cason S. Zobol G. Fierro G. Lucch R. Soav P. Berardi
a Fisica Sanitaria, Azienda USL, Bologna, Italy; b Medicina Nucleare, Azienda
USL, Bologna, Italy
Introduction: In order to verify the possible sensitivity variation using semi-
quantitative analysis, a comparison was performed between myocardial
tomoscintigraphy of a phantom under different setup and equipment, along
with a clinical cases review.
Materials and Methods: Acquisitions were carried out with heart insert
ECT/CAR/I, positioned inside the cylindrical phantom ‘Standard-Jaszczak’
and equipped by two warm sectors (one with 50% of phantom activity con-
centration, the other with 20%). Scans were performed both by a dedicated
gamma camera (CardioMD – Philips) under different setup (i.e. by differ-
ent distances between detectors and phantom), and by a General Purpose
gamma camera (Infinia – GE).
Images were processed using the Filtered Back Projection (FBP) algorithm
and, when possible, the iterative one (Astonish – Philips).
Then, comparisons between different acquisitions were performed using
the regional perfusion semi-quantitative analysis with polar maps.
Finally, a patient’s case review was carried out.
Results: In all FBP images the 50% insert involved 3 segments of maps, in-
cluding 2 identified as pathological, while the 20% one has involved 5 of
which only 3 are pathological.
In CardioMD images reconstructed with Astonish, the 50% insert involved
2 segments of maps, both pathological, while the 20% one has involved 4,
all reported as pathological.
Positive patients’ review also showed higher scores when iterative recon-
struction was used, while in negative patients there were no differences.
Conclusions: Semi-quantitative analysis with polar maps showed that there
are no significant differences between the images acquired with different
setup and equipment, when reconstructed by FBP. The use of the Aston-
ish iterative algorithm instead has highlighted, compared to FBP, greater
sensitivity both in phantom and in patients.
C.374
STUDY OF WHOLE BODY RESIDENCE TIMES FOR 131I TREATMENT OF
THYROID CANCER
M. Paoli *, E. Di Nicola, P. D’Avenia, M. Camarda, L. Montani, G. Rossi,
S. Fattori. ASUR Marche, Macerata, Italy
Introduction: The existence of a rare and precious archive, which con-
tains measures of whole body counts for 1156 patients affected from
thyroid carcinoma and subjected to ablation therapy with 131I, was the
start for this study which aims to establish a reference standard for the
residence times of 131I for patients hospitalized in nuclear medicine
department.
Materials and Methods: The method is based on the measures of total body
counts, made by Geiger–Müller counters present in protected patient rooms,
after administration of therapeutic activity of 131I in order to ablate the
thyroid remnant.
Patients were divided into two groups: 869 at first treatment with 131I and
287 treated with 131I for persistent disease after first treatment; for each
of them the measures of total body counts have been normalized with the
first measure and then it was calculated the residence time in the whole
body through a bi-exponential fit of the counts/time curve.
The concept of residence time is expressed in units of time but it is the
number of nuclear transitions that occur in a certain region in a time in-
terval normalized to the activity administered (Bq-s/Bq or μCi-h/μCi).
Results: The results obtained for residence times are:
First treatment: mean [h] 15.89, standard deviation 5.87, IC at 95%
[15.50;16.28];
nth treatment: mean [h] 19.07, standard deviation 6.45, IC at 95%
[18.33;19.82].
Conclusions: The efficacy of the nuclear medicine therapy is connected to
the absorbed dose by the target that strongly depends on the time in which
the radioiodine remains inside the tumor cell.
From the results it is evident that the mechanism of wash-out of the ra-
dioiodine I in whole body is slower for patients reprocessed.
The high abundance of patients made it possible to calculate precise es-
timates of the confidence level of residence time’s average value; also the
two intervals are quite distinct as thus also the two statistical populations.
C.375
RETROSPECTIVE ANALYSIS OF DOSE–RESPONSE FOR HCC LESIONS
TREATED WITH 90Y RESIN MICROSPHERES
C. Pettinato C. Mosconi A. Cappelli S. Civollan P. Pin F. Monari
B. Angelell E. Nobil S. Fanti R. Golfier a U.O. Fisica Sanitaria, AOU
S.Orsola Malpighi, Bologna, Italy; b U.O. Radiologia, AOU S.Orsola Malpighi,
Bologna, Italy; c U.O. Medicina Interna, AOU S.Orsola Malpighi, Bologna, Italy;
d U.O. Radioterapia, AOU S.Orsola Malpighi, Bologna, Italy; eU.O. Oncologia, AOU
S.Orsola Malpighi, Bologna, Italy; f U.O. Medicina Nucleare, AOU S.Orsola
Malpighi, Bologna, Italy
Aim: The aim of this study was to evaluate the correlation between tumor
dose and local tumor response.
Materials and Methods: From September 2010 to October 2014, 48 pa-
tients affected by HCC have been treated with 90Y resin microspheres. All
pts received an intra-hepatic infusion of 150 MBq of 99mTc-MAA to cal-
culate lung and extra-hepatic shunts and to perform lesion and whole liver
dosimetry using the MIRD formalism. The activity to be injected was cal-
culated using the BSA formula and was modulated based on tumor and
normal liver doses, limiting the dose to whole normal liver to about 30 Gy.
Results: The mean injected 90Y activity was 1.5 (r: 0.4–2.4 GBq). The mean
tumor volume was 286 cc (range: 43 cc–2566 cc), while the average dose
was 258 Gy (range: 13–858 Gy). Tumors with smaller volumes received
higher doses. The average doses to tumors with volumes below 100 cc,
between 100 and 200 cc, between 200 and 500 cc and above 500 cc were
respectively 436 Gy (95% IC: 267.6–603.5 Gy), 263 Gy (95% IC: 195.6–
329.4 Gy), 207.8 Gy (95% IC: 157.8–257.8 Gy) and 56.2 Gy (95% IC: 27.1–
85.3 Gy). 25/48 pts received an average tumor dose greater than 200 Gy.
9/25 pts showed a complete response and an average survival >12 months.
9/25 pts had a good response, while 7/25 pts had a stable response on the
treated lesion but a worsening of the disease due to progression of non-
treated lesions. 3/23 pts, who received less than 200 Gy, had a complete
response of the treated lesion, 14/23 had a good response and 6 had stable
disease. Our results suggest that big tumors (>300 cc) are responsive to lower
average doses.
Conclusions: Average tumor dose based on 99mTc-MAA SPECT images is
a good prognostic value to predict tumor response to 90Y resin microsphere
treatments in patients affected by HCC. Our results showed that 36% of
tumors that received more than 200 Gy had complete response while 64%
of tumors had stable or good response for more than one year.
C.376
RADIOMETABOLIC THERAPY WITH 131I FOR HYPERTHYROIDISM FROM
GRAVES’ DISEASE. FIRST EXPERIENCES IN SASSARI HOSPITAL
F. Pinna R. Bona C. Marchion A. Poggi M. Tampon A. Span
P.G. Marini a Azienda Ospedaliero Universitaria, Sassari, Italy; b Azienda
Sanitaria Locale n° 1, Sassari, Italy
Introduction: In our center we are treating patients with Graves’s disease
with 131I for 2 years.
The administered activity is customized by determining the parameters
related to the kinetics of radiopharmaceutical uptake by a nonlinear mixed-
effects model and effective thyroid volumes by echography. To emphasize
the importance of this choice, we analyzed the dependence of the admin-
istered 131I activity by the calculation method.
Materials and Methods: The method used allows to determine kinetic pa-
rameters (maximum uptake Umax and time effective half-life T1/2eff) fitting
thyroid uptake measurements at 4, 24 and 72 hours from administration
of 1,5 MBq of 131I, through a University of Massachusetts tool, which makes
use of an algorithm based on results of reference
e110 Abstracts/Physica Medica 32 (2016) e97–e115