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108 CYCLOTRON DESIGNS FOR HADRONTHERAPY WITH CYCLINACS
S44 scanner BASTEI at GSI. For off-line tests without ion beam irradiation two 22Na point sources with a total activity of 1.37 MBq were stacked at the center of the field of view of the PET scanner. One-dimensional periodic motion with peak-to-peak amplitudes from 1 mm to 108 mm was generated by a motion device. Sinusoidal as well as cos4-patterns were investigated. The deviation of the reconstructed b+-activity distribution from an ideal static reference distribution is evaluated depending on motion amplitude, number of motion phases and phase separation by time or amplitude. The noise-robustness of the 4D MLEM algorithm is demonstrated with in-beam PET data taken during the irradiation of a moving (20 mm peak-to-peak amplitude) PMMA target with a monoenergetic 12Cbeam. The applied dose distribution of linear shape was centered at the horizontal midplane of the field of view. The listmode PET data stream was thinned to a patient-like counting statistic by randomly rejecting coincidence events. The reconstructed activity distributions are compared for different counting statistics and reconstruction algorithms. Conclusion: The 4D MLEM algorithm overcomes the drawback of intrinsic low counting statistic in single motion phases. Motion related artifacts are vanished by using an adequate number of motion phases. Resulting b+-activity distributions contain a low noise level for high dose experiments as well as for patient-like counting statistics. Furthermore, it allows the implementation of different motion models by adapting the transformation matrices between the different motion phases. Therefore, it is suggested to apply the 4D MLEM algorithm for the tomographic reconstruction of in-beam PET data taken under intrafractional motion. 108 CYCLOTRON DESIGNS FOR HADRONTHERAPY WITH CYCLINACS A. Garonna1, A. Laisn1, U. Amaldi2 1 TERA Foundation, Italy 2 CERN This work presents new superconducting compact (as opposed to separated-sector) cyclotron designs for injection in CABOTO, a linac developed by the TERA Foundation delivering C6+/H2+ beams up to 400 MeV/u for ion beam therapy. This association of a variable energy linac injected by a fixed energy cyclotron is called cyclinac. Two superconducting cyclotron designs are compared under the same design constraints and methods: a synchrocyclotron and an isochronous cyclotron, both at the highest possible magnetic field and with an output energy of 230 MeV/u. This energy allows to use the cyclotron as a stand-alone accelerator for protontherapy. Once the optimal cyclotron is determined, lower energy cyclotrons can easily be designed. The short pulse length (1.5 μs), fast repetition rate (100300 Hz) and small beam transmission of the cyclinac (0.2 %) require intense pulsed ion sources. To deliver the desired clinical dose rate, the average pulse current of 60 eμA of C6+ at 300 Hz can be produced by three commercial EBIS (EBIS-SC by Dreebit Gmbh) operating at 100 Hz and connected to the beamline in alternating mode. A multicusp ion source is sufficient to produce
ICTR-PHE 2012 compatible H2+ beams. The synchrocyclotron design features a central magnetic field of 5 T, an axisymmetric pole and a constant field index of 0.02. The beam is injected axially with a spiral inflector (K=1.4). A static magnetic perturbation of 0.1 T and 5 deg width boosts the beam radial gain per turn (with no emittance degradation) by exciting the first radial integer resonance and thus allows beam ejection with moderate beam losses (30 %). The RF system operates in first harmonic (Q=2500). The 180 deg Dee provides 28 kV peak voltage and the RF is modulated (30-38 MHz) by a rotating capacitor (90-900 pF). The synchrocyclotron's best features are the simple and compact magnet (300 tons) and the low RF power requirements (30 kW power supply). The isochronous cyclotron design features a 3.2 T central magnetic field, four sectors and a pole characterized by elliptical gaps in the hills (3-30 mm) and in the valleys (11-50 cm). Spiraling is minimized (80 deg total hill axis rotation) and beam ejection is achieved with a single electrostatic deflector placed inside an empty valley. The two RF cavities operate in fourth harmonic at 98 MHz (Q=7100). The RF system provides peak voltages of 70-120 kV and is powered by a single 100 kW unit. The synchrocyclotron reliability is brought into question by the need of a rotating capacitor and by the complexity of the injection and ejection systems. However, the isochronous cyclotron requires a much more complex magnet. Overall, the isochronous cyclotron is a better solution compared to the synchrocyclotron, because it is as compact but more reliable. To quantitatively determine the industrial and clinical optimum for the CABOTO injection energy, three complementary isochronous cyclotrons of 70, 120 and 170 MeV/u are studied, based on the 230 MeV/u design. The optimal cyclotron energy strongly depends on the clinical aim of the facility. For a dual proton and carbon ion centre, the best compromise between clinical flexibility, accelerator size and power consumption is to accelerate particles up to 150 MeV/u in the cyclotron. In this configuration, the 150 MeV/u isochronous cyclotron has similar weight and spiraling as the most widely used cyclotron for protontherapy (C235 by IBA S.A.), CABOTO is 24 m long and the overall power consumption of the cyclinac is 650 kW. Adding to these characteristics, the property of fast energy variation of the linac makes the cyclinac presented in this work a strongly competitive accelerator for dual proton and carbon ion therapy. 109 TUMOUR MICROENVIRONMENT AND INTRATUMOURAL DISTRIBUTION OF THERAPEUTIC ANTIBODIES L. Koi1, K. Brüchner2, L. Helbig1, M. Zenker3, J.M. Heldt3, R. Bergmann3, B. Mosch3, H.J. Pietzsch3, J. Steinbach3, M. Baumann1, D. Zips1 1 Experimental RT, OncoRay, Dresden, Germany 2 Laser-Radiooncology, OncoRay, Dresden, Germany 3 Radiopharmacy, HZDR, Oncoray, Germany Purpose: The efficacy of therapeutic antibodies in combination with irradiation also dependents on the distribution in the tumour, i.e. the accessibility to radioresistent areas. Here we investigated in
ICTR-PHE 2012 compatible H2+ beams. The synchrocyclotron design features a central magnetic field of 5 T, an axisymmetric pole and a constant field index of 0.02. The beam is injected axially with a spiral inflector (K=1.4). A static magnetic perturbation of 0.1 T and 5 deg width boosts the beam radial gain per turn (with no emittance degradation) by exciting the first radial integer resonance and thus allows beam ejection with moderate beam losses (30 %). The RF system operates in first harmonic (Q=2500). The 180 deg Dee provides 28 kV peak voltage and the RF is modulated (30-38 MHz) by a rotating capacitor (90-900 pF). The synchrocyclotron's best features are the simple and compact magnet (300 tons) and the low RF power requirements (30 kW power supply). The isochronous cyclotron design features a 3.2 T central magnetic field, four sectors and a pole characterized by elliptical gaps in the hills (3-30 mm) and in the valleys (11-50 cm). Spiraling is minimized (80 deg total hill axis rotation) and beam ejection is achieved with a single electrostatic deflector placed inside an empty valley. The two RF cavities operate in fourth harmonic at 98 MHz (Q=7100). The RF system provides peak voltages of 70-120 kV and is powered by a single 100 kW unit. The synchrocyclotron reliability is brought into question by the need of a rotating capacitor and by the complexity of the injection and ejection systems. However, the isochronous cyclotron requires a much more complex magnet. Overall, the isochronous cyclotron is a better solution compared to the synchrocyclotron, because it is as compact but more reliable. To quantitatively determine the industrial and clinical optimum for the CABOTO injection energy, three complementary isochronous cyclotrons of 70, 120 and 170 MeV/u are studied, based on the 230 MeV/u design. The optimal cyclotron energy strongly depends on the clinical aim of the facility. For a dual proton and carbon ion centre, the best compromise between clinical flexibility, accelerator size and power consumption is to accelerate particles up to 150 MeV/u in the cyclotron. In this configuration, the 150 MeV/u isochronous cyclotron has similar weight and spiraling as the most widely used cyclotron for protontherapy (C235 by IBA S.A.), CABOTO is 24 m long and the overall power consumption of the cyclinac is 650 kW. Adding to these characteristics, the property of fast energy variation of the linac makes the cyclinac presented in this work a strongly competitive accelerator for dual proton and carbon ion therapy. 109 TUMOUR MICROENVIRONMENT AND INTRATUMOURAL DISTRIBUTION OF THERAPEUTIC ANTIBODIES L. Koi1, K. Brüchner2, L. Helbig1, M. Zenker3, J.M. Heldt3, R. Bergmann3, B. Mosch3, H.J. Pietzsch3, J. Steinbach3, M. Baumann1, D. Zips1 1 Experimental RT, OncoRay, Dresden, Germany 2 Laser-Radiooncology, OncoRay, Dresden, Germany 3 Radiopharmacy, HZDR, Oncoray, Germany Purpose: The efficacy of therapeutic antibodies in combination with irradiation also dependents on the distribution in the tumour, i.e. the accessibility to radioresistent areas. Here we investigated in