18-05-2012, 01:56 PM
Magnet Design of the Superconducting
Cyclotron for Carbon Therapy
[attachment=22366]
Abstract
Korea Institute of Radiological & Medical Sciences
(KIRAMS) has started the development of a superconducting
cyclotron for carbon therapy. The goal of the development is to
produce a 430 MeV/u carbon beam for medical use. The magnet
system is composed of one set of NbTi superconducting coils and
four spiral sectors with a return yoke. The hill angular widths, hill
gaps, and spiral angles with radius have been designed for the
isochronous magnetic field. The spiral sector shape and the beam
characteristics of the designed magnetic field have been
presented.
I. INTRODUCTION
T is well known that particle therapy is more effective than
radiation therapy for cancer treatment. Especially, the
relative biological effectiveness (RBE) value of carbon ion is
higher than that of proton [1]. The number of heavy ion therapy
facilities is growing in the world; five facilities are operating
and eight facilities are under construction or being proposed
[2]-[4]. In Korea, the first heavy ion therapy project, the Korea
Heavy Ion Medical Accelerator (KHIMA) project, has been
launched in April 2011 [4]. One accelerator, three treatment
rooms, and one research room will be constructed at KHIMA
center in Busan, Korea. We are expecting cancer treatment
would be started in December 2016. It took one year to choose
the accelerator between a cyclotron and a synchrotron. The
design studies of a superconducting cyclotron have been started
in April 2011. The other systems of KHIMA facility are being
studied simultaneously and three articles were presented in
IPAC 2011 [5]-[7].
The superconducting cyclotron will accelerate carbon ions,
12C6+ 12.5 keV/u to 430 MeV/u. Carbon ions will be injected by
an axial inflector and extracted by an electric deflector. 1720
MeV of bending limit is required to a magnet for the cyclotron.
NbTi superconducting coil is used to produce a high magnetic
field. In this paper.
DESIGN MODEL
Because the geometry of the magnet is reflection symmetric
in x-y plane and is four-fold rotational symmetric in z-axis, An
1/8 of numerical model was used in magnetic field simulation
by OPEAR3d (Fig. 2).
DESIGN RESULTS
The current density of the superconducting coil is 2253
A/cm2 and the maximum magnetic field in the coil is 3.07 T.
The height and diameter of the whole magnet is 4.44 m and
7.78 m, respectively. The pole radius is 2.05 m.
The hill gap is decreased linearly from 0.08 m to 0.02 m with
the radius and the valley gap is 1.84 m. The maximum hill angle
is 49.44° at extraction radius, r = 1.98 m. After the extraction
radius, the hill has been trimmed for deflected beam passing.
The overall spiral angle is increased from 0° to 80° linearly. To
adjust vertical betatron oscillation (or tune) around outer region
of the hill, the spiral angle was decreased in that region (Fig. 4).
The designed spiral hill with design points are shown in Fig. 5.
The dashed lines in valley region are acceleration gaps that
have been used for beam tracking calculation.
CONCLUSION.
We have designed the superconducting magnet for 12C6+
acceleration to 430 MeV/u. The overall structure of the
superconducting magnet and detailed shape of the spiral hill
have been presented. The listed characteristics of magnetic
field and beam tracking show that the magnetic field of the
magnet is well designed. Studies for the interference with other
systems are now under way. More detailed design for central
region and extraction area is required. Current agenda for
technical design is aiming August 2012. We are also
developing measurement system and shimming method for
manufacturing.
Cyclotron for Carbon Therapy
[attachment=22366]
Abstract
Korea Institute of Radiological & Medical Sciences
(KIRAMS) has started the development of a superconducting
cyclotron for carbon therapy. The goal of the development is to
produce a 430 MeV/u carbon beam for medical use. The magnet
system is composed of one set of NbTi superconducting coils and
four spiral sectors with a return yoke. The hill angular widths, hill
gaps, and spiral angles with radius have been designed for the
isochronous magnetic field. The spiral sector shape and the beam
characteristics of the designed magnetic field have been
presented.
I. INTRODUCTION
T is well known that particle therapy is more effective than
radiation therapy for cancer treatment. Especially, the
relative biological effectiveness (RBE) value of carbon ion is
higher than that of proton [1]. The number of heavy ion therapy
facilities is growing in the world; five facilities are operating
and eight facilities are under construction or being proposed
[2]-[4]. In Korea, the first heavy ion therapy project, the Korea
Heavy Ion Medical Accelerator (KHIMA) project, has been
launched in April 2011 [4]. One accelerator, three treatment
rooms, and one research room will be constructed at KHIMA
center in Busan, Korea. We are expecting cancer treatment
would be started in December 2016. It took one year to choose
the accelerator between a cyclotron and a synchrotron. The
design studies of a superconducting cyclotron have been started
in April 2011. The other systems of KHIMA facility are being
studied simultaneously and three articles were presented in
IPAC 2011 [5]-[7].
The superconducting cyclotron will accelerate carbon ions,
12C6+ 12.5 keV/u to 430 MeV/u. Carbon ions will be injected by
an axial inflector and extracted by an electric deflector. 1720
MeV of bending limit is required to a magnet for the cyclotron.
NbTi superconducting coil is used to produce a high magnetic
field. In this paper.
DESIGN MODEL
Because the geometry of the magnet is reflection symmetric
in x-y plane and is four-fold rotational symmetric in z-axis, An
1/8 of numerical model was used in magnetic field simulation
by OPEAR3d (Fig. 2).
DESIGN RESULTS
The current density of the superconducting coil is 2253
A/cm2 and the maximum magnetic field in the coil is 3.07 T.
The height and diameter of the whole magnet is 4.44 m and
7.78 m, respectively. The pole radius is 2.05 m.
The hill gap is decreased linearly from 0.08 m to 0.02 m with
the radius and the valley gap is 1.84 m. The maximum hill angle
is 49.44° at extraction radius, r = 1.98 m. After the extraction
radius, the hill has been trimmed for deflected beam passing.
The overall spiral angle is increased from 0° to 80° linearly. To
adjust vertical betatron oscillation (or tune) around outer region
of the hill, the spiral angle was decreased in that region (Fig. 4).
The designed spiral hill with design points are shown in Fig. 5.
The dashed lines in valley region are acceleration gaps that
have been used for beam tracking calculation.
CONCLUSION.
We have designed the superconducting magnet for 12C6+
acceleration to 430 MeV/u. The overall structure of the
superconducting magnet and detailed shape of the spiral hill
have been presented. The listed characteristics of magnetic
field and beam tracking show that the magnetic field of the
magnet is well designed. Studies for the interference with other
systems are now under way. More detailed design for central
region and extraction area is required. Current agenda for
technical design is aiming August 2012. We are also
developing measurement system and shimming method for
manufacturing.