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  • 1
    Abstract: Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra. For the application of laser-driven beams in PT, new solutions for beam transport, such as beam capture, integrated energy selection, beam shaping and delivery systems are required due to the specific beam parameters. The generation of these beams are limited by the low repetition rate of high-power lasers and this limitation would require alternative solutions for tumour irradiation which can efficiently utilize the available high proton fluence and broad-energy spectra per proton bunch to keep treatment times short. This demands new dose delivery system and irradiation field formation schemes. In this paper, we present a multi-functional light-weight and compact proton gantry design for laser-driven sources based on iron-less pulsed high-field magnets. This achromatic design includes improved beam capturing and energy selection systems, with a novel beam shaping and dose delivery system, so-called ELPIS. ELPIS system utilizes magnetic fields, instead of physical scatterers, for broadening the spot-size of broad-energetic beams while capable of simultaneously scanning them in lateral directions. To investigate the clinical feasibility of this gantry design, we conducted a treatment planning study with a 3D treatment planning system augmented for the pulsed beams with optimizable broad-energetic widths and selectable beam spot sizes. High quality treatment plans could be achieved with such unconventional beam parameters, deliverable via the presented gantry and ELPIS dose delivery system. The conventional PT gantries are huge and require large space for the gantry to rotate the beam around the patient, which could be reduced up to 4 times with the presented pulse powered gantry system. The further developments in the next generation petawatt laser systems and laser-targets are crucial to reach higher proton energies. However, if proton energies required for therapy applications are reached it could be possible in future to reduce the footprint of the PT facilities, without compromising on clinical standards.
    Type of Publication: Journal article published
    PubMed ID: 28609301
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  • 2
    Abstract: Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.
    Type of Publication: Journal article published
    PubMed ID: 28828925
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  • 3
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  PTCOG 48; Meeting of the Particle Therapy Co-Operative Group; 20090928-20091003; Heidelberg; DOC09ptcog057 /20090924/
    Publication Date: 2009-09-25
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
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  • 4
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Jahrestagung der Gesellschaft für Medizinische Ausbildung - GMA; 20091008-20091010; Freiburg im Breisgau; DOC09gmaT4V068 /20090902/
    Publication Date: 2009-09-02
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 5
    ISSN: 1435-0130
    Keywords: Neovascularization ; Free muscle grafts ; Endothelial cells ; Vein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 78 male Wistar rats, the gracilis anterior muscles were devascularized and transplanted into the femoral region. In one experimental group, the muscles were transplanted with their innervation intact, in a second group denervated muscles were transplanted. The ipsilateral saphenous artery and vein were dissected out of their adventitia and implanted axially into the muscle graft. The entire transplant was encased in silicone foil in order to prevent neovascularization and reinnervation emanating from the host area. Neovascularization of the ischaemic innervated and denervated muscle grafts, containing approximately 300 muscle fibers, followed in a centrifugal pattern. The newly formed sinusoidal capillary network originated from the vein. Within the first four days, endothelial cells of the implanted vein had loosened their intercellular contacts, proliferated and migrated through the vascular wall into the muscle graft. The initially solid capillary sprouts opened up, starting at the lumen of the vein. Within two weeks a complete endomysial capillary network was reestablished. Possible and conceivable clinical uses of these findings are discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-0130
    Keywords: Revascularization ; Vessel implantation ; Bone grafts ; Corrosion casts ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The microsurgical implantation of a saphenous vascular axis into free transplanted autologous isolated rib segments in Beagle dogs led to complete revascularization of the bone after two, three and four weeks. Indian ink and Mercox-injected specimens showed a vascular network which penetrated the entire cortical layer. Semi-thin sections revealed osteoblasts and osteoclasts visible in the canals of the revascularized cortical layer, while the control specimen without vessel implantation showed nothing but ground substance. The revascularized bones did not contain any necrotic areas. The newly formed vascular system consisted of arteries, veins and their anastomoses. The veins appeared to produce a greater number of new vessels than the arteries.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 412 (2001), S. 717-720 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] By freezing out the motion between particles in a high-energy storage ring, it should be possible to create threads of ions, offering research opportunities beyond the realm of standard accelerator physics. The usual heating due to intra-beam collisions should completely vanish, giving rise to a ...
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spontaneous recombination of highly charged ions with free electrons in merged velocity matched electron and ion beams has been observed in earlier experiments to occur at rates significantly higher than predicted by theoretical estimates. To study this enhanced spontaneous recombination, laser induced recombination spectra were measured both in velocity matched beams and in beams with well defined relative velocities, corresponding to relative electron-ion detuning energies ranging from 1 meV up to 6.5 meV where the spontaneous recombination enhancement was found to be strongly reduced. Based on a comparison with simplified calculations, the development of the recombination spectra for decreasing detuning energies indicates additional contributions at matched velocities which could be related to the energy distribution of electrons causing the spontaneous recombination rate enhancement.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 115 (1998), S. 29-36 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Facing the difficulties associated with the preparation of crystalline ion beams in heavy ion storage rings we propose two complementary table top schemes to elucidate fundamental issues like stability criteria for moving ion crystals at low velocities. One is based on a small radio-frequency quadrupole (RFQ) storage ring, where by laser cooling Mg+ ion crystals at rest were observed, but conceptionally modified with additional acceleration electrodes and manufactured with highest mechanical precision. The other approach suggested here implies the use of an RFQ ion guide for the lateral confinement of the ions combined with buffer gas viscous damping, which could lead to an ideal starting condition for first time direct three-dimensional laser cooling in a single pass arrangement.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on the generation of 750 mW cw laser radiation at a wavelength of 257 nm obtained by frequency doubling the green Ar+ line in a Brewster-cut BBO crystal placed in the spherical focus of an external ring resonator. The system is optimized for laser cooling studies of intense 83.7 MeV 21Mg+ ion beams at the ESR dedicated to the investigation of space charge-dominated beams.
    Type of Medium: Electronic Resource
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