Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    German Medical Science GMS Publishing House; Düsseldorf
    In:  PTCOG 48; Meeting of the Particle Therapy Co-Operative Group; 20090928-20091003; Heidelberg; DOC09ptcog223 /20090924/
    Publication Date: 2009-09-25
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    German Medical Science GMS Publishing House; Düsseldorf
    In:  PTCOG 48; Meeting of the Particle Therapy Co-Operative Group; 20090928-20091003; Heidelberg; DOC09ptcog177 /20090924/
    Publication Date: 2009-09-25
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Keywords: SYSTEM ; SIMULATION ; ION-BEAMS ; ACCELERATED PROTON
    Abstract: This work is a feasibility study of a radiation treatment unit with laser-driven protons based on a state-of-the-art energy selection system employing four dipole magnets in a compact shielded beamline. The secondary radiation emitted from the beamline and its energy selection system and the resulting effective dose to the patient are assessed. Further, it is evaluated whether or not such a compact system could be operated in a conventional treatment vault for clinical linear accelerators under the constraint of not exceeding the effective dose limit of 1 mSv per year to the general public outside the treatment room. The Monte Carlo code Geant4 is employed to simulate the secondary radiation generated while irradiating a hypothetical tumor. The secondary radiation inevitably generated inside the patient is taken into account as well, serving as a lower limit. The results show that the secondary radiation emanating from the shielded compact therapy system would pose a serious secondary dose contamination to the patient. This is due to the broad energy spectrum and in particular the angular distribution of the laser-driven protons, which make the investigated beamline together with the employed energy selection system quite inefficient. The secondary radiation also cannot be sufficiently absorbed in a conventional linear accelerator treatment vault to enable a clinical operation. A promising result, however, is the fact that the secondary radiation generated in the patient alone could be very well shielded by a regular treatment vault, allowing the application of more than 100 fractions of 2 Gy per day with protons. It is thus theoretically possible to treat patients with protons in such treatment vaults. Nevertheless, the results show that there is a clear need for alternative more efficient energy selection solutions for laser-driven protons.
    Type of Publication: Journal article published
    PubMed ID: 25267383
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Keywords: QUANTIFICATION ; SKIN ; FREQUENCY ; LYMPHOCYTES ; dosimetry ; MICROBEAM RADIATION-THERAPY ; MICRONUCLEUS RSMN ASSAY ; SYNCHROTRON MICROBEAM ; EBT3 FILMS ; MICROIRRADIATION
    Abstract: The risk of developing normal tissue injuries often limits the radiation dose that can be applied to the tumour in radiation therapy. Microbeam Radiation Therapy (MRT), a spatially fractionated photon radiotherapy is currently tested at the European Synchrotron Radiation Facility (ESRF) to improve normal tissue protection. MRT utilizes an array of microscopically thin and nearly parallel X-ray beams that are generated by a synchrotron. At the ion microprobe SNAKE in Munich focused proton microbeams ("proton microchannels") are studied to improve normal tissue protection. Here, we comparatively investigate microbeam/microchannel irradiations with sub-millimetre X-ray versus proton beams to minimize the risk of normal tissue damage in a human skin model, in vitro. Skin tissues were irradiated with a mean dose of 2 Gy over the irradiated area either with parallel synchrotron-generated X-ray beams at the ESRF or with 20 MeV protons at SNAKE using four different irradiation modes: homogeneous field, parallel lines and microchannel applications using two different channel sizes. Normal tissue viability as determined in an MTT test was significantly higher after proton or X-ray microchannel irradiation compared to a homogeneous field irradiation. In line with these findings genetic damage, as determined by the measurement of micronuclei in keratinocytes, was significantly reduced after proton or X-ray microchannel compared to a homogeneous field irradiation. Our data show that skin irradiation using either X-ray or proton microchannels maintain a higher cell viability and DNA integrity compared to a homogeneous irradiation, and thus might improve normal tissue protection after radiation therapy.
    Type of Publication: Journal article published
    PubMed ID: 25936621
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    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
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Abstract: BACKGROUND AND PURPOSE: High-precision radiotherapy (RT) requires precise positioning, particularly with high single doses. Fiducial markers in combination with onboard imaging are excellent tools to support this. The purpose of this study is to establish a pancreatic cancer mouse model for high-precision image-guided RT (IGRT) using the liquid fiducial marker BioXmark (Nanovi, Kongens Lyngby, Denmark). METHODS: In an animal-based cancer model, different volumes of BioXmark (10-50 microl), application forms, and imaging modalities-cone-beam computer tomography (CBCT) incorporated in either the Small Animal Radiation Research Platform (SARRP) or the small-animal micro-CT Scanner (SkyScan; Bruker, Brussels, Belgium)-as well as subsequent RT with the SARRP system were analyzed to derive recommendations for BioXmark. RESULTS: Even small volumes (10 microl) of BioXmark could be detected by CBCT (SARRP and Skyscan). Larger volumes (50 microl) led to hardening artefacts. The position of BioXmark was monitored at least weekly by CBCT and was stable over 4 months. BioXmark was shown to be well tolerated; no changes in physical condition or toxic side effects were observed in comparison to control mice. BioXmark enabled an exact fusion with the original treatment plan with less hardening artefacts, and minimized the application of contrast agent for fractionated RT. CONCLUSION: An orthotopic pancreatic tumor mouse model was established for high-precision IGRT using a fiducial marker. BioXmark was successfully tested and provides the perfect basis for improved imaging in high-precision RT. BioXmark enables a unique application method and optimal targeted precision in fractionated RT. Therefore, preclinical trials evaluating novel fractionation regimens and/or combination treatment with high-end RT can be performed.
    Type of Publication: Journal article published
    PubMed ID: 28808749
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    Keywords: IRRADIATION ; radiotherapy ; Germany ; VOLUME ; CELL-LINES ; RADIATION-THERAPY ; DOSE-RESPONSE ; HEAD ; RBE ; RELATIVE BIOLOGICAL EFFECTIVENESS ; proton therapy ; CAPACITY ; BEAMS ; Biological optimization ; Plan comparison
    Abstract: Purpose: To investigate in a simulation study whether using a variable relative biological effectiveness (RBE) in calculation and optimization of intensity-modulated proton therapy (IMPT) instead of using an RBE of 1.1 would result in significant changes in the RBE-weighted dose (RWD) distributions. Methods and Materials: For 4 patients with head-and-neck tumors, three IMPT plans were prepared respectively. The first plan was physically optimized (IMPT-PO plan), and the RWD was calculated with a constant RBE of 1.1. Then the plan's RWD was recalculated (IMPT-R plan) using a variable RBE model taking into account the linear energy transfer (LET) and tissue-specific radiobiological parameters. The third IMPT plan was optimized using a biological optimization routine (IMPT-BO plan). Results: Comparing the IMPT-PO and IMPT-R plans, we observed that the RWD in radioresistant tissues was more sensitive to the LET than in radiosensitive tissues. The IMPT-R plans were in general more inhomogeneous than the IMPT-PO plans. The differences of RWD distributions for all volumes between IMPT-PO and IMPT-BO plans complied with predefined dose volume constraints. The average LET was significantly lower in IMPT-BO plans than in IMPT-R plans. Conclusion: In radioresistant normal tissues caution has to be used regarding the LET distribution because these are most sensitive to changes in the LET. Biological optimization of IMPT plans based on the organ-specific biological parameters and LET distributions is feasible.
    Type of Publication: Journal article published
    PubMed ID: 20382482
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    German Medical Science GMS Publishing House; Düsseldorf
    In:  70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie; 20190512-20190515; Würzburg; DOCP182 /20190508/
    Publication Date: 2019-05-09
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...