the segment of the top-implart accelerator up to 150 mev has been funded by regione lazio and is...
TRANSCRIPT
The segment of the TOP-IMPLART accelerator up to 150 MeV has
been funded by Regione Lazio and is under realization at ENEA-
Frascati Center choose as a test site. The accelerator is based on
the 7 MeV injector consisting in a 3 MeV RFQ followed by a DTL
up to 7 MeV (PL-7ACCSYSHITACHI model) followed by a vertical
and an horizontal beam transport line matching the beam to the
following accelerating modules.
TOP-IMPLART LINEAR ACCELERATOR FOR PROTON THERAPY:
LAYOUT AND FIRST RADIOBIOLOGICAL RESULTS AT LOW ENERGYMaria Antonella Tabocchini1, Alessandro Ampollini2, Giulia Bazzano2, Francesca Marracino2, Concetta Ronsivalle2, Monia Vadrucci2, Maria Balduzzi3,
Clarice Patrono3, Claudia Snels3, Antonella Testa3, Pasqualino Anello1, Cinzia De Angelis1, Giuseppe Esposito1, Marco D’Andrea4, Lidia Strigari4
7 MeV7 MeV 150 MeV150 MeV35 MeV35 MeV 230MeV230MeV
Head-NeckTumors
Head-NeckTumors
In-vitro and in-vivoRadiobiology
In-vitro and in-vivoRadiobiology
In vitroRadiobiology
In vitroRadiobiology
18 MeV18 MeV Deep TumorDeep Tumor
The section of the accelerator up to 11.6 MeV module, is
already installed and has been tested. Additional modules
will be added to the injector leading proton energy to 30, 70
and 150 MeV in a step by step project. …..
The 7 MeV injector proton beam was used for radiobiology experiments
devoted to a biological characterization of the beams in terms of the cell
killing. A dedicated radiobiology vertical beam line has been implemented.
To this purpose, a 90° vertical bending magnet is placed in the middle of
the low energy beam transport line. In this way it is possible to select the
requested energy of protons impinging on the cells.
The first radiobiological experiments were carried out to characterize the proton beam. To this purpose, cell
killing experiments were conducted at the TOP-IMPLART vertical transport line on V79 and CHO cells. Irradiations
have been performed with protons extracted in air and impinging on the cells with energy of 5 MeV (incident
LET=7.7 keV/μm in MS20); the clonogenic survival was evaluated in the dose range 0.5-8 Gy.
90° magnet
Acknowledgements: Thanks are due to FILAS-Regione Lazio for funding the TOP-IMPLART Project, coordinated by L. Picardi, C.Marino (ENEA) and E. Cisbani (ISS), and to R.Cherubini (LNL-INFN) for his prime scientific support.
Sample holder Beam line
1Istituto Superiore di Sanita (ISS) and INFN-Gr.coll.Sanita (Italy), 2ENEA-Frascati, Rome (Italy), 3ENEA- Casaccia, Rome (Italy),
4Regina Elena National Cancer Institute, IFO, Rome (Italy)
INFN-LNL radiobiology irradiation setup (in air): single sample holder and set of sample holders placed on the revolving system remotely controlled during measurements.
The same sample holders especially designed for
proton irradiation at the LNL (Belli et al, Nucl Instr Meth
1987) have been used at the TOP-IMPLART during
irradiation of Chinese hamster cells with protons of 5
MeV, corresponding to an incident LET (in MS20
tissue) of 7.7 keV/µm. Gaf-Chromic EBT3 film have
shown a uniformity of 90% on the irradiated area.
Calibration curves Dose vs. netOD of the EBT3 films irradiaed at the LNL with 5MeV protons at the dose rate of 2.1 Gy/min
LAYOUT
FIRST RADIOBIOLOGICAL RESULTS
DOSIMETRY
: 0.208 ± 0.016β: 0.020 ± 0.003
FUTURE DEVELOPMENTS
TOP (Oncological Therapy with Protons) - IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) project curried out by ENEA, ISS and IFO as the end-user, is based
on a compact pulsed 230 MeV proton LINAC designed for fully active scanning (3+1)D in intensity (instantaneous released dose), energy (depth) and transversal position (x-y). Peculiar
characteristics of the system are: modularity, pulsed operation naturally suited to IMPT, fast energy variation, high quality beam, high dose rate capability, reduced beam losses and
reduced neutron production along the accelerating sections. The TOP-IMPLART proton beams will also be used for in vivo” and “in vitro” radiobiological studies.
DOSE DELIVERY MONITOR OF THE TOP-IMPLART
PROTON THERAPY BEAM
A dose delivery monitor was specifically designed for the TOP
IMPLART beam characteristics. It will measure the beam
intensity profile, position and direction to monitor the fully active
3+1D (x, y, z and intensity) pulsed beam. The monitor system
consists of segmented ionization chambers and it is driven by
dedicated electronics.
Assembled chamber
prototype
First electron beam tests of the chamber prototype of the dose delivery monitor show good noise
characteristics and excellent beam profile measurements. Further and more accurate
characterization tests are in progress, while a new, consolidated version of the chamber and the
electronics is under development.
SCATTERING CHAMBER AND MULTISAMPLE HOLDER
Energy measurement of a proton beam after a
scattering process
The scattering process happens inside a scattering
chamber with a vacuum of P~ 10−3 Pa. Target and
detectors can be moved inside the chamber. The energy
of the scattered proton is measured by a Lithium drifted
Silicon detector with 5 mm of thickness. The angle is
determined by a mechanic positioning system of the
detector that uses a quadrature encoder with a resolution
better than 0,004 degrees.
0.01
0.1
1
0 2 4 6 8 10
SF 1
SF 2
SF 3
SF
Sur
vivi
ng F
ract
ion
Dose / Gy
CHO TOP protons (3 exps)
0.01
0.1
1
0 2 4 6 8 10
SF 1SF 2SF 3SF 4SF
Sur
vivi
ng F
ract
ion
Dose / Gy
V79 TOP protons (4 exps)
The dose-response curves for clonogenic survival were found
to be characterized by an initial shoulder (more pronunced in
V79 than in CHO cells) followed by a straight portion, that can
be well fitted by a linear-quadratic function of the dose. The
results on V79 cells, widely used in hadrontherapy
experiments, were found in good agreement with the previous
data obtained at LNL. Also the data obtained using CHO cells
were consistent with literature results (Tang et al., British
Journal of Cancer 1997). Experiments are planned with a
differernt proton energy to extend the radiobiological
characterization of the TOP-IMPLART proton beam.: 0.186 ± 0.019β: 0.090 ± 0.003
Dosimetry was carried out using GafChromic EBT3 films, calibrated at the INFN-LNL Laboratories with a
proton beam having the same energy, at the entrance of the EBT3 film, as the protons produced by the
TOP-IMPLART accelerator for these radiobiological experiments. (Vadrucci et al., accepted for
pubblication in Medical Physics)
Low energy Radiobiology Experiments: beam parameters
Energy Energy spread LET Fluence Pulse
CurrentPulse
DurationRepetition Frequency Dose Rate
5 MeV 0.1 MeV 7.7 keV/m 105÷106
protons/cm2 0.16 A 13 s 10 Hz 2 – 5 Gy/min
V79 (4 exps)
CHO (3 exps)
Dos
e to
MS2
0 (G
y)
netOD
Belli et al., International Journal of Radiation Biology 1999
Fig.1 Survival curves for V79 cells irradiated with X-rays and protons with different LET. Each data point represent the mean of at least seven independent experiments and the error bars denote one standard error of the mean.
: 0.208 ± 0.017 β: 0.020 ± 0.003
Table 2 Parameters obtained from the best fit od the s rvival curves
RBE-LET relationship for cell inactibation and mutation induced by low energy protons in V79 cells: further results at the LNL facilitymylar foil
protons
cell monolayer