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

A.28

ACCURACY OF A DEFORMABLE IMAGE REGISTRATION ALGORITHM

S. Calusi

, a ,

G. Labanca

a ,

L. Noferin

i b ,

C. Talamonti

a , c ,

G. Simontacchi

d ,

S. Pallott

a a , c .

Department of Clinical and Experimental Biomedical Sciences-

Mario Serio, University of Florence, Firenze, Italy;

Health Physics Unit, AOU

Careggi, Firenze, Italy;

Medical Physics Unit, AOU Careggi, Firenze, Italy;

Radiotherapy Unit, AOU Careggi, Firenze, Italy

Introduction:

The accuracy of deformable image registration (DIR) tech-

niques has an important role in adaptive radiation therapy. DIR algorithms

are in fact used to adapt the contours outlined in planning CT in order to

follow anatomical change occurring during radiotherapy treatment. In this

study, we propose a quantitative validation of the deformable image reg-

istration algorithm implemented in MIM-Maestro using real phantoms and

synthetic images.

Materials and methods:

The MIM software uses a free-form intensity-

based algorithm to perform CT-CT DIR; it also implements the RegRefine

tool to manually correct deformed images. The DIR algorithm was tested

considering deformations that typically occur in head and neck area: bending

and tumour shrinking. Two phantoms mimicking these two situations were

prepared and consecutive CT acquisitions were performed applying in-

creasing degrees of deformation. DIR performances on images with different

artificially changed contrasts and using RegRefine tool were also evalu-

ated. DIR accuracy was estimated using DICE similarity index (DSI) between

corresponding ROIs; ROI volume variation and distances (R) between cor-

responding markers.

Results:

Increase bending – DSI range between 0.96 and 0.94 for all the

bending considered; the worst result corresponds to the maximum flec-

tion. Maximum R (1.8 mm) was measured in correspondence of rigid

structures close to big deformations.

Tumour shrinking – DSIs of rigid structures, close to the varying volume,

range between 0.94 and 0.97 for maximum deformations.

Decrease contrast – DSIs decrease with the contrast between objects down

to 0.91 for the lower contrast. In this situation an R up to 2.2 mm was

measured.

RegRefine – DSIs improve when the tool is used; differences are greater

at higher strains.

Conclusions:

The performance of MIM DIR algorithm remains reason-

ably good even in extreme bending, volume variations and poor contrast

situations. The use of RegRefine improves registration results.

http://dx.doi.org/10.1016/j.ejmp.2016.01.032

A.29

INNOVATIVE APPROACHES IN THE DOSIMETRY OF LASER-DRIVEN

PROTON BEAMS FOR FUTURE HADRONTHERAPY APPLICATIONS

G. Candiano

* , a ,

A. Amic

o a , b ,

M. Borghesi

c ,

G.A.P. Cirrone

a ,

G. Cuttone

a ,

D. Doria

c ,

G. La Rosa

a ,

R. Leanza

a , b ,

R. Manna

a ,

L. Mant

i d , e ,

V. Marches

e a ,

G. Milluzzo

a , b ,

F. Perozziello

d , e ,

G. Petringa

a , b ,

I. Pipek

a ,

L. Romagnani

f ,

F. Roman

o a ,

F. Schillac

i a ,

V. Scuder

i a , g ,

A. Tramontana

a , b .

Laboratori Nazionali

del Sud, Istituto Nazionale di Fisica Nucleare, Catania, Italy;

Dipartimento di

Fisica e Astronomia, Università degli studi di Catania, Catania, Italy;

Centre

for Plasma Physics, School of Mathematics and Physics, The Queen’s University

of Belfast, Belfast, UK;

INFN Sezione di Napoli, Complesso Universitario M. S.

Angelo, Napoli, Italy;

Università di Napoli Federico II, Complesso Universitario

M. S. Angelo, Napoli, Italy;

LULI, École Polytechnique, CNRS, CEA, UPMC, Paris,

France;

Department of Experimental Program at ELI-Beamlines, Institute of

Physics of the ASCR, ELI-Beamlines project, Prague, Czech Republic

Introduction:

Nowadays, the innovative high power laser-based particle

acceleration technique is one of the most attractive topics in the relativ-

istic laser-plasma interaction research and represents a concrete future

alternative in the field of particle acceleration. In this framework, the purpose

of the international ELIMED network consists of demonstrating that laser-

driven proton beams can be used for multidisciplinary applications

investigating, particularly, new approaches in the hadron-therapy field.

Methods and materials:

Due the extremely high dose rates per pulse of

laser-driven beams, we proposed innovative approaches for dosimetry of

laser-driven beams using GafChromic Film (GCF) and CR-39.

GCFs, used in stack configuration, provide a measurement of the energy

spectrum of an incident radiation: knowing the thickness, composition and

density of each GCF, it is possible to retrieve the energy spectra through

an iterative procedure. Another important application is related to the mea-

surement of the effective area when performing absolute dosimetry with

a Faraday cup, which is independent of the dose rate as well.

The nuclear track detectors, CR-39, reveal very high sensitivity and uni-

formity of response and permit the direct measure of particle fluence

independent of the particle dose rate.

Results:

GCF spectroscopic procedures have been experimentally verified

and tests with CR-39 have been performed with proton beams acceler-

ated by the superconducting cyclotron and by tandem of the LNS-INFN in

Catania. Further studies have been carried out using laser-driven beams

at the TARANIS facility in Belfast and at the LULI laser facility in Paris.

Conclusion:

Extensive studies were carried out on innovative detectors for

absolute and relative dosimetry for laser-driven beams. The results ob-

tained in the mentioned experimental campaigns will be presented.

http://dx.doi.org/10.1016/j.ejmp.2016.01.033

A.30

PATIENT-SPECIFIC PLAN QA IN ACTIVE PENCIL BEAM SCANNING WITH

PROTON AND CARBON ION BEAMS: A NEW SOFTWARE SOLUTION TO

SUPPORT TREATMENT PLANNING WORKFLOW

A. Carlino

, a , b ,

M. Hager

a ,

M. Marrale

b ,

M. Stock

a ,

S. Vatnitsky

a .

EBG

MedAustron GmbH, Wiener Neustadt, Austria;

Department of Physics and

Chemistry, University of Palermo, Palermo, Italy

Introduction:

At MedAustron, the active pencil beam scanning technique

with protons and carbon ions has been implemented. A commercial so-

lution, based on the use of multiple ionization chambers for a quasi-

three dimensional dosimetric verification, has been acquired. However, no

specific software to support the selected dosimetric equipment and inter-

face it to the TPS is commercially available. In this paper we present an

innovative, in-house developed software solution that makes the treat-

ment planning verification workflow more efficient and faster.

Materials and methods:

Dose distribution for patient plan is optimized

and computed by the RayStation TPS. The PTW equipment for plan veri-

fication consists of a holder which fixes up to 24 PinPoint ionization

chambers in different planes, allowing a quasi-three dimensional verifi-

cation of delivered dose distributions.

Results:

In order to verify the delivery of each single beam of a compos-

ite treatment plan, dose distribution for each beam is recomputed in a virtual

water phantom. To support the next step a python script has been imple-

mented in the TPS to select the position of the holder within the water

phantom and extract dose and dose gradient values at the effective point

of measurement for each PinPoint ionization chamber. The developed ‘Plan

Verificator’ software in C# supports the verification by remotely control-

ling the PTW equipment, carrying out measurements, comparing the

measurement results with the planned dose, analyzing and exporting the

data into a QA report for documentation.

Conclusions:

The patient-specific plan verification procedure is even more

demanding for complex delivery techniques such as active scanning with

proton and carbon ion beams. Moreover, the lack of commercial software

solution to interface two different medical products (RayStation TPS on the

one side and the PTW equipment on the other side) has been overcome

by the integration of a script and the software ‘Plan Verificator’.

http://dx.doi.org/10.1016/j.ejmp.2016.01.034

A.31

DEVELOPMENT AND APPLICATION OF A TRANS-RECTAL US PROBE

INTEGRATED WITH MOSKIN DOSIMETERS: IN VIVO RECTAL WALL

MEASUREMENTS DURING HDR PROSTATE BRACHYTHERAPY

M. Carrara

* , a ,

C. Tenconi

a ,

G. Rossi

a ,

M. Borron

i a ,

A. Cerrott

a a ,

S. Grisotto

a ,

B. Pappalard

i a ,

D. Cutaja

r b ,

M. Petasecca

b ,

M. Lerch

b ,

J. Bucci

c ,

C. Fallai

a ,

G. Gambarin

i d ,

A. Rosenfel

d b ,

E. Pignol

i a .

Fondazione IRCCS Istituto Nazionale

dei Tumori, Milano, Italy;

Centre for Medical Radiation Physics, Wollongong,

Australia;

St. George Hospital, Sydney, Australia;

Istituto Nazionale di Fisica

Nucleare, Milano, Italy

Introduction:

In collaboration with the Centre for Medical Radiation Physics,

University of Wollongong, a novel prototype of trans-rectal ultrasound (TRUS)

Abstracts/Physica Medica 32 (2016) e1–e70