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

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Results: The developed GUI displays graphs corresponding to system re-
sponse function, ESF, MTF, NPS and DQE. The parameters calculated on the
tested clinical system with our software were compared with those pro-
vided by the detector manufacturer: a good agreement resulted.
Conclusion: It is expected that the application of our software could help
physicists in assessing image quality of digital detectors during quality
control, without mistakes that may occur when images are manually
analysed.
B.272
DENTAL HYBRID CONE BEAM CT EFFECTIVE DOSES AND PATIENT
RADIOLOGICAL REPORT
A. Loria *, C.R. Gigliotti, A. del Vecchio, F. De Cobelli, M. Del Maschio,
R. Calandrino. IRCCS San Raffaele Scientific Institute, Milano, Italy
Introduction: Recently a new pure hybrid 3D Cone Beam CT (CBCT) NewTom
VGi Evo, was installed in our Diagnostic Department.
This machine is not a usual dentistry device used to obtain CT, OPT and
cephalometric exams, it’s a pure CT scan and, due to its technical features
and to the possibility to choose a wide range of exposition parameters, is
also suitable for maxillofacial and ENT surgery. Furthermore, this partic-
ular model, also allows a real 2D acquisition and not only a bidimensional
reconstruction of a 3D image.
Our aim is to provide organs and body effective dose measurements in order
to optimize the exposure protocols for every single clinical application and
to comply Ministerial Regulations G.U. No.124 regarding the imperative to
declare maximum expected dose to the patients in the informed consent.
Materials and Methods: Thermo-luminescent dosimeters (TLD) were placed
in 42 sites throughout the layers of the head and neck of a tissue-equivalent
phantom (Alderson RANDO), identifying the 16 most important OARs. Two
or three TLD were placed in each organ depending on the size. Three more
dosimeters were used to measure skin dose for neck and cheeks. For each
technique three exposures were done. Afterwards doses delivered by CBCT
panoramic view modality and by a digital OPT exam were compared.
Average tissue absorbed dose, weighted equivalent dose and effective dose
were calculated for each ICRP 103 anatomical sites.
Results: In the worst exposition condition (maxillary 3D scan), the total
effective dose resulted 0.14 ± 0.02 mSv while crystalline lens equivalent dose
resulted 1.9 ± 0.2 mSv. Effective doses for 2D panoramic modality with CBCT
and OPT were comparable as expected.
Conclusions: The clinical applications of this CBCT involve very different
radiation doses. Our topic is to provide accurate dosimetric information to
clinicians for each exposition possibilities, in order to allow the best choice
for every single patient and to prepare specific informed consents.
B.273
EVALUATION OF THE ACTUAL PERCEPTION OF MEDICAL IMAGES
INFORMATIVE CONTENT BY VARYING MEDICAL DISPLAYS
PERFORMANCES
M. Lualdi * D. Baldari G. Calareso S. Canestrini F. Cartia
M. Castellani C. Cicero C.M. Ciniselli D. Cusumano C. Ferranti
F.G. Grec A. Laffranchi A. Lorenzoni A. Marchian A. Primolevo
G. Scaperrott C. Sicilian P. Verderio D. Vergnaghi E. Pignoli a SSD
Fisica Medica, Fondazione IRCCS Istituto Nazionale Tumori, Milano, Italy; b SC
Radiologia, Fondazione IRCCS Istituto Nazionale Tumori, Milano, Italy; c SC
Radiologia, ULSS 3, Bassano del Grappa, Italy; d SC Medicina Nucleare,
Fondazione IRCCS Istituto Nazionale Tumori, Milano, Italy; e SC Statistica Medica,
Biometria e Bioinformatica, Fondazione IRCCS Istituto Nazionale Tumori, Milano,
Italy; f Scuola di Specializzazione in Fisica Medica, Università Statale, Milano,
Italy; g SC ICT-SIA, Fondazione IRCCS Istituto Nazionale Tumori, Milano, Italy
Introduction: Medical decisions regarding treatment and care are made
on the basis of the informative content of the images presented on medical
displays. After a pilot study, we started, at July of 2015, a large study more
specifically designed to identify the more suitable physical parameters of
medical displays for a faithful reproduction of medical images and to quan-
tify the possible bias in medical images interpretation.
Materials and Method: Five radiological modalities have been enrolled in
our research: planar mammography, tomosynthesis, traditional RX, com-
puted tomography and nuclear medicine. For each modality, a diagnostic
question has been chosen and altogether more than 300 images with in-
creasing difficulty of interpretation have been selected by a senior radiologist.
Participant radiologists with different level of expertise are blindly evalu-
ating all the images on various displays each with a prefixed set-up (i.e.
different levels of maximum and minimum luminance, contrast ratio and
spatial resolution). The pattern of reproducibility will be evaluated by re-
sorting to appropriate index of agreement.
Results: Preliminary results highlight that one of the most relevant factor
related to tomosynthesis exams is the luminance level of the displays. Spe-
cifically displays with an up to 1000 cd/m2 luminance seem to allow a easier
detection of microcalcifications. For nuclear medicine exams, a high con-
trast ratio seems to facilitate the detection of low uptake areas even if
displays with a low spatial resolution are used.
Conclusion: Our preliminary results confirm the importance of the di-
splay’s setting in the medical decision process. The large study actually
ongoing will better identify the most suitable and optimized setup for each
of the considered radiological modalities to avoid visual discomfort and,
in some cases, inaccurate interpretation of the evaluated image.
B.274
A NOVEL COMPUTERIZED METHOD FOR QUALITY ASSURANCE OF
MEDICAL ULTRASOUND PROBES
M. Lualdi L. Gamberal E. Pignoli a Fondazione IRCCS Istituto Nazionale
Tumori, Milan, Italy; b LD-Brane srls, Milan, Italy
Introduction: The benefits from continuous ultrasound (US) image quality
assurance (QA) are widely recognized to help in reducing the risk of in-
accurate diagnosis. QA protocols for B-mode probes are based on tissue
mimicking phantom studies, conventionally performed with manual ac-
quisitions followed by visual or automated image analysis. In this work
we describe a new home-made computerized method for QA of US
probes.
Materials and Method: The presented software is able to manage all the
phases of QA for US probes: to guide images acquisition, to measure and
linearize the post processing look up table and to evaluate the image pa-
rameters requested by the most recent standard recommendations: echo
level dynamic range, contrast resolution, signal-to-noise ratio, penetra-
tion depth, uniformity, dead zone, axial and lateral resolution, vertical and
horizontal distance accuracy and size of anechoic masses. The software was
evaluated by performing measurements on a tissue-mimicking phantom
with 80 medical transducers. An analysis of software output was finally
performed, focused on the evaluation of the historical trend of the ob-
tained results when compared with previous measurements or reference
values.
Results: The test performed on the US probes lead, for some parameters,
to results comparable to those obtained with other available software. On
the contrary, for other parameters (signal-to-noise ratio, lateral resolu-
tion and uniformity) significant differences were pointed out, probably due
both to the method and to accuracy in calculation. The principal improve-
ments offered by the novel software are the quantitative evaluation of crystal
damages and the rigorous analysis of spatial parameters for all image
formats.
Conclusion: The results obtained confirm that the developed software ef-
ficiently supports the tester during the image acquisition and performs a
rigorous analysis of the acquired images, thus representing a valid and rig-
orous tool for QA of medical US probes.
B.275
CONE BEAM COMPUTED TOMOGRAPHY (CBCT) CHARACTERIZATION FOR
IN-VIVO CANCELLOUS BONE STRUCTURAL MEASUREMENTS
M. Maddalo * F. Baruffaldi C. Fersini C. Pinardi F. Dusi
L. Mascaro R. Maroldi R. Moretti a Medical Physics Unit, Hospital Spedali
Civili, Brescia, Italy; b Department of Medical and Surgical Specialties,
e81 Abstracts/Physica Medica 32 (2016) e71–e96