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

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F.458
SIMULTANEOUS USING OF TWO SUPERFICIAL HYPERTHERMIA ANTENNAS
A. Di Dia S. Depalma S. Brescian A. Maggio A. Miranti M. Poli
E. Garibald P. Gabriele M. Stas a FPO-IRCCS, Medical Physics, Candiolo
Cancer Institute, Candiolo, TO, Italy; b Dipartimento scienza applicata e
tecnologia, Politecnico di Torino, Torino, TO, Italy; c FPO-IRCCS, Radiotherapy
Department, Candiolo Cancer Institute, Candiolo, TO, Italy
Introduction: The purpose of this work is the 3D-modeling/simulation of
the simultaneous using of two antennas of our hyperthermia equipment.
Materials and methods: The hyperthermia device is equipped with double
superficial antennas, operating at a frequency of 434 MHz. with a water
automatic superficial cooling device (water bolus). The applicators geom-
etry has been reproduced in the CAD environment with a professional
software based on the FDTD processing methods. In order to identify the
distribution of specific absorption power rate (SAR), simulations have been
performed varying the relative antennas positions on several phantoms (skin,
fat, muscle). The accuracy of the solver has been set at −40 dB with a time
simulation limit of 50 pulses. The SAR calculation has been calculated as
point SAR with a default stimulation power of 1 W peak power flowing into
the structure.
Results: The simulation showed that, increasing the fat thickness, the tem-
peratures were gradually reduced in the underlying muscle tissue (0.2
degrees less for every 5 mm more fat). In the fat layer, for each 5 mm of
thickness, the temperature increased by about 0.6 degrees and in the cutting
plane the intensity of absorbed power decreases very rapidly with increas-
ing distance from the projection of the slot. Varying the thickness of bolus
from 10 to 20 mm, the setting of the applicator coupled to the tissue model
underwent small changes of the reflected power and, at the operating fre-
quency, the model with thickness 17.5 mm showed to have the best
coefficient of reflection. The simultaneous use of the two antennas dem-
onstrated that, when the relative antennas positions increasing, the second
applicator’s resonance is distributed. At the relative distance of 0, 1, 2 cm
we obtained 52%, 31% and 10% isoSAR maximum.
Conclusions: The numerical simulation demonstrates that it is possible to
use both antennas in safety without possibility of hot spots in the tissue,
varying also the thickness of the bolus.
F.459
OPENING FRACTION TIME OF INTERNAL JUGULAR VALVES USING
ULTRASOUND TRACES
N. Mohammed M. Vannin E. Menegatti M. Tessari P. Zombon
G. Di Domenico F. Sisin M. Gambaccin a Department of Physics and
Earth Sciences, Ferrara, Italy; b Vascular Disease Center, Ferrara, Italy
Introduction: Internal jugular vein valves IJVV, are the only venous valves
between the brain and the heart. It is known that their incompetence can
influence the brain drainage. For this reason it is important to establish a
gold standard for their opening fraction time (OFT) in physiological and
pathological conditions.
In this work three different methods are used to estimate OFT over a sample
of young healthy subjects.
Material and method: B-mode and M-mode ultrasound traces associ-
ated with ECG are used to analyse the opening–closure cycles of IJV leaflets.
25 healthy young subjects, age ranging from 20 to 25 years old were en-
rolled in this study to be scanned with GE Ultrasound System.
Three methods, (i) Curved lines searching algorithm (CLSA) method, which
is an open source software using a local approach classifying of the image
pixels as belonging to a curve or not and; (ii) ROI measurements of ImageJ
software; (iii) Doppler blood flow analysis are herein used to estimate the
opening fraction time (OFT) of the IJVV through a cardiac cycle.
Result: The opening fraction time of IJVV through one cardiac cycle were ob-
tained for all the three proposed methodologies. The main results show that
the valves are open according to the ECG events and Doppler blood velocity.
Conclusion: In this work we shown that OTF can be easily estimated using
a non invasive methodology. This parameter could be used in the future
for clinical applications.
F.460
IMPLEMENTATION OF A QUALITY ASSURANCE PROGRAM FOR
ULTRASOUND TRANSDUCERS
L. Montani *, M. Paoli, M. Camarda, P. D’Avenia, E. Di Nicola, G. Rossi,
S. Fattori. Servizio di Fisica Medica AV3 ASUR Marche, Macerata, Italy
Introduction: A Quality Assurance (QA) program for ultrasound (US) trans-
ducers has been implemented in the Area Vasta 3 of Marche ASUR. We plan
to apply it to all linear and convex transducers for B-mode imaging present
in the about 20 hospitals and ambulatories of the district.
Materials and Methods: The US devices present in the health facilities are
different in their manufacturer, model, type, use and age. The general purpose
CIRS phantom (model 054GS) used for quality controls allows to investi-
gate the main image quality parameters. In this study we report the results
obtained in terms of five parameters: image uniformity, penetration depth,
spatial resolution (axial and lateral at different depth), length accuracy at
different depths and dead zone. A qualitative score (poor, sufficient, good)
was applied to the results, following criteria by AAPM 22-TG1-1998 or
Cozzolino et al. in Radiol Med 2010 115:668-677
Results: Two of the 31 considered transducers had crystal damages and
needed to be replaced. The tested 14 convex and 15 linear transducers had
central frequencies in the range 3.5–6 MHz and 7–10 MHz respectively.
Image uniformity evaluation was qualitative and resulted in 14% poor, 24%
sufficient, 62% good. The other results are: penetration depth 17% poor, 17%
sufficient, 66% good; axial resolution 3% poor, 6% sufficient, 91% good; lateral
resolution 13% poor, 16% sufficient, 72% good; dead zone 14% poor, 10% suf-
ficient, 76% good.
Conclusions: A QA program consisting of periodic quality controls is useful
for monitoring image quality over time, in order to foresee image degra-
dation and transducers damage. To this aim reproducible acquisition
parameters have to be defined in order to acquire comparable measure-
ments over time. Even if some parameters are difficult to be quantified and
can result in user-dependent qualitative scoring, baseline values have to
be acquired and recommended levels have to be defined to provide cor-
rective measures in case of image degradation.
F.461
HOW HTA METHODOLOGY IS ABLE TO HELP THE DECISION MAKER TO
INTRODUCE MOST SUITABLE TECHNOLOGY
A. Occhipint A. Pedalino A. Rabito E. Ruscic a UOS Fisica Sanitaria
– ASP7, Ragusa, Italy; b Ingegneria Clinica – ASP7, Ragusa, Italy
Introduction: The purpose of this work is to show how a successful HTA
multidisciplinary approach does not necessarily lead to the introduction
of a new more profitable technology.
Evaluation has been made by comparing FibroScan with shear wave
elastography, technologies that both enable to establish the stage of liver
fibrosis.
Materials and Method: HTA analysis has been performed in the first place
by identifying target population and then by comparing the two technolo-
gies through comparative scientific works and by carrying out an economic
evaluation on the basis of factors such as: costs of technology, mainte-
nance, any structural adjustment costs and personnel costs. Organisational,
social and legal aspects have also been taken into account.
Results: Scientific analysis has shown a diagnostic overlap of the two tech-
nologies, while from the economic point of view it has shown that the
introduction of shear wave elastography could prove more favourable com-
pared to FibroScan.
The net estimated economic benefit of the elastography should point in
the direction of the cheaper technology, but since the purchase is subject
to the inclusion of patients in protocols for the use of new generation
antifibrosis drugs, a query has been filed to AIFA (Italian Drug Agency) on
the possibility of using a system other than the Fibroscan and the re-
sponse obtained states that only the use of technology Fibroscan allows
the refund of the new antifibrosis drug costs.
Conclusions: Though the above mentioned HTA evaluation has identified
the shear wave elastography as the best technology for the area needs –
being equivalent from an efficiency point of view and more convenient from
an economic point of view – such evaluation does not allow access to ex-
e136 Abstracts/Physica Medica 32 (2016) e135–e137