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

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for this reason TAVI dosimetric data are very rare and we have verified that
our results are near the same of those presented in a recent publication
(Catheterization and Cardiovascular Intervention, 2015, 85, 1256–1261).
Conclusions: Automated methods of radiation dose data collection permit
a detailed analysis of a great amount of data and an easy determination
of local dose reference levels for interventional cardiology procedures. We
have verified that our data are dosimetrically correct and that we have never
exceeded the DAP threshold limit of 500 Gycm^2.
B.265
HOW TO DEFINE LOCAL DIAGNOSTIC REFERENCE LEVELS FOR CT, MG
AND XA USING A DOSE TRACKING SOFTWARE
C. Ghetti * S. Filice O. Ortenzia F. Palleri M. Sireus G. Crisi
a Department of Medical Physics, University Hospital of Parma, Parma, Italy;
b University of Cagliari, Cagliari, Italy; cDepartment of Neuroradiology, University
Hospital of Parma, Parma, Italy
Introduction: Dose optimization in high dose radiological examinations
is a mandatory issue: in this study local Diagnostic Reference Levels (lDRLs)
for the most frequent procedures performed in our Radiology Depart-
ment were established using a radiation dose tracking system in order to
have an optimization tool and to face the requests of the new Euratom di-
rective 2013/59.
Materials and Method: Radiation dose data (CTDI, DLP, AGD, fluoro time,
DAP) collection was realized using a dose tracking software (Radimetrics,
Bayer) connected to 5 CT scanners, 2 clinical mammographic units and 5
angiographic systems.
From the beginning of 2015 we have analyzed 27,700 CT acquisitions, 4600
mammographic radiograms, 2100 interventional procedures (cardiac, neuro
and body).
We have defined our lDRLS and we have compared our data with Dlgs 187/
00 and with the recent literature.
Results: For head, sinuses, dental, chest, cardiac, spine, chest-abdomen and
CAP CT scans we have defined the 75thpercentiles of CTDIvol and DLPtot.
We have established our lDRLS for CA, PTCA, CA+PTCA,TAVI, arteriogra-
phy, vertebroplasty, IVC angiography, PTC+PTBD, PTA and varicocele in term
of fluoro time, fluoro DAP and total DAP.
We have evaluated the AGD mean and the 75th percentile for each mam-
mographic radiogram, for the whole examination and for the magnification
images.
We have verified that most of our data are dosimetrically correct and we
have focused which are the procedures that need an optimization.
Conclusions: Automated methods of radiation dose data collection allow
a fast and detailed analysis of a great amount of data and an easy deter-
mination of lDRLs for different radiological procedures.
Alert, productivity and benchmarking tools, available in Radimetrics, enable
to control in real time the dosimetric trend of our radiological examina-
tions and to perform the necessary corrective actions.
B.266
EVALUATION OF THE VOLUMETRIC DOSE IN DIGITAL BREAST
TOMOSYNTHESIS
G. Aser P. Barone C. Greco A. Guel L. Raffael S. Spampinat
a PH3DRA Laboratories, Dipartimento di Fisica e Astronomia, Università di
Catania&INFN, Sez. CT, Catania, Italy; b Azienda Ospedaliero, Universitaria
Policlinico Vittorio Emanuele, Catania, Italy; cScuola di Specializzazione in Fisica
Medica, Scuola Facoltà di Medicina, Università di Catania, Catania, Italy
Introduction: Digital Breast Tomosynthesis (DBT) is often used in clinical
exams to integrate the information obtained with conventional mammog-
raphy and to investigate the breast thickness at different depths through
image projections. The aim of this work is to analyse the dose distribu-
tion along the three dimensions, within a phantom that simulates the breast.
Materials and Methods: To perform dose measurements, Gafchromic® XR-
QA2 films were used. To obtain a calibration curve that links absorbed dose
with Pixel Value, different pieces of film (3 × 3 cm2) were irradiated with
increasing known doses and digitised with a commercial flatbed scanner
using a standard protocol for film dosimetry (72 dpi, 48 bit colour depth).
To obtain the two- and three-dimensional dosimetric information, a home-
made phantom, assembled with10 × 10 cm2 slices of 5 mm solid water (ten
slices) and eleven slices of XR-QA2 films was used. Dose maps as a func-
tion of depth were obtained from DBT exposures in AEC modality. The films
were digitised with the scanner (150 dpi, 48 bit colour depth), Image J and
Origin software were used, respectively, for red channel data extraction and
dose values analysis.
Results: After the image acquisition, a ROI was selected in central posi-
tion in order to obtain the dose values useful to Percentage Depth Dose
(PDD) reconstruction. A (16,04 ± 0,80) mGy surface dose, considered in the
reference area (6 cm from chest wall), was obtained while at the maximum
depth a dose of (0,96 ± 0,05) mGy was evaluated.
Furthermore, the 2D map of each sheet results within 10%. An increment
of the dose values is imputable to the Hall effect that amplifies the energy
absorption in the chest wall.
Conclusions: The dosimetry performed by XR-QA2 Gafchromic® films
showed that the 2D and 3D distributions during a mammography exam in
DBT modality are uniform along the direction of the support plane of the
breast. The PDD behaviour shows a dose decrement with respect to depth.
B.267
RETROSPECTIVE DOSE EVALUATION IN ADULTS UNDERGOING RECURRING
CT EXAMINATIONS: LAST FIVE YEARS EXPERIENCE IN OUR INSTITUTION
S. Grisotto E. Mazzarell M. Borron R. Gall F.G. Grec E. Pignoli
A. Marchianò a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori,
Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori,
Milano, Italy
Introduction: A retrospective study of dosimetric data of most fre-
quently performed adult CT examinations has been implemented to
determine the impact of new available technologies in dose reduction.
Materials and Methods: Dosimetric data of CT scans of adult patients re-
peating the same diagnostic examination in the last five years have been
compared to each other. Head, chest and chest-abdomen examinations per-
formed on Siemens Somatom Sensation CT scanner until November 2011
and on Siemens Definition Flash CT scanner (replacing the previous one)
have been considered. For both CT scanners exams have been performed
using tube current modulation system Care Dose 4D (except in the case
of head examinations for which it has been introduced in spring 2014).
Sinogram-Affirmed Iterative Reconstruction (SAFIRE) has also been imple-
mented on the newer CT device. Reference and effective mAs, mean CTDIvol
and DLP provided by the scanners have been recorded for each exam veri-
fying patient size constancy over time. Size specific dose estimate (SSDE)
corrected for water equivalent diameter (WED) has been calculated from
AP and LL patient dimensions measured from images. Image quality has
been evaluated by means of HU standard deviation in ROIs drawn in the
same uniform regions of the image. About 30 patients have been ana-
lyzed for each type of examination.
Results: For head examinations the use of Care Dose 4D and SAFIRE has
enabled a mean dose reduction of about 17% at constant image quality. For
chest examinations it has been possible to reduce both dose and noise by
about 30%. For chest-abdomen examinations only a slight dose reduction
has been shown because aggressive dose reduction could compromise lesion
detectability.
Conclusions: The introduction of tube current modulation and iterative
reconstruction has generally proved to be very effective at reducing dose,
most of all to patients undergoing frequent CT examinations over time.
B.268
PROJECT OF AN AUTOMATIC SYSTEM FOR TRADITIONAL RADIOLOGY
EQUIPMENTS AND IMAGE DETECTORS QUALITY CONTROLS
S. Grisotto E. Mazzarella M. Borroni F.G. Greco E. Pignoli
A. Marchianò a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori,
Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori,
Milano, Italy
e79 Abstracts/Physica Medica 32 (2016) e71–e96