982 research outputs found
Technologies for Delivery of Proton and Ion Beams for Radiotherapy
Recent developments for the delivery of proton and ion beam therapy have been
significant, and a number of technological solutions now exist for the creation
and utilisation of these particles for the treatment of cancer. In this paper
we review the historical development of particle accelerators used for external
beam radiotherapy and discuss the more recent progress towards more capable and
cost-effective sources of particles.Comment: 53 pages, 13 figures. Submitted to International Journal of Modern
Physics
Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress
It has been known for about sixty years that proton and heavy ion therapy is
a very powerful radiation procedure for treating tumours. It has an innate
ability to irradiate tumours with greater doses and spatial selectivity
compared with electron and photon therapy and hence is a tissue sparing
procedure. For more than twenty years powerful lasers have generated high
energy beams of protons and heavy ions and hence it has been frequently
speculated that lasers could be used as an alternative to RF accelerators to
produce the particle beams necessary for cancer therapy. The present paper
reviews the progress made towards laser driven hadron cancer therapy and what
has still to be accomplished to realise its inherent enormous potential.Comment: 40 pages, 24 figure
The Nano-X Linear Accelerator: A Compact and Economical Cancer Radiotherapy System Incorporating Patient Rotation.
Rapid technological improvements in radiotherapy delivery results in improved outcomes to patients, yet current commercial systems with these technologies on board are costly. The aim of this study was to develop a state-of-the-art cancer radiotherapy system that is economical and space efficient fitting with current world demands. The Nano-X system is a compact design that is light weight combining a patient rotation system with a vertical 6 MV fixed beam. In this paper, we present the Nano-X system design configuration, an estimate of the system dimensions and its potential impact on shielding cost reductions. We provide an assessment of implementing such a radiotherapy system clinically, its advantages and disadvantages compared to a compact conventional gantry rotating linac. The Nano-X system has several differentiating features from current radiotherapy systems, it is [1] compact and therefore can fit into small vaults, [2] light weight, and [3] engineering efficient, i.e., it rotates a relatively light component and the main treatment delivery components are not under rotation (e.g., DMLCs). All these features can have an impact on reducing the costs of the system. In terms of shielding requirements, leakage radiation was found to be the dominant contributor to the Nano-X vault and as such no primary shielding was necessary. For a low leakage design, the Nano-X vault footprint and concrete volume required is 17 m2 and 35 m3 respectively, compared to 54 m2 and 102 m3 for a conventional compact linac vault, resulting in decreased costs in shielding. Key issues to be investigated in future work are the possible patient comfort concerns associated with the patient rotation system, as well as the magnitude of deformation and subsequent adaptation requirements
Combined tumour treatment by coupling conventional radiotherapy to an additional dose contribution from thermal neutrons
Aim: To employ the thermal neutron background in conventional X-rays radiotherapy treatments in order to add a localized neutron dose boost to the patient, enhancing the treatment effectiveness.
Background: Conventional linear accelerators for radiotherapy produce fast secondary neutrons with a mean energy of about 1 MeV due to (\u3b3, n) reaction. This neutron field, isotropically distributed, is considered as an extra unaccounted dose during the treatment. Moreover, considering the moderating effect of human body, a thermal neutron field is localized in the tumour area: this neutron background could be employed for Boron Neutron Capture Therapy (BNCT) by previously administering a boron (10B enriched) carrier to the patient, acting as a localized radiosensitizer. The thermal neutron absorption in the 10B enriched tissue will improve radiotherapy effectiveness.
Materials and Methods: The feasibility of the proposed method was investigated by using simplified tissue-equivalent phantoms with cavities in correspondence of relevant tissues or organs, suited for dosimetric measurements. A 10 cm
7 10 cm square photon field with different energies was delivered to the phantoms. Additional exposures were implemented, using a compact neutron photo-converter-moderator assembly, with the purpose of modifying the mixed photon-neutron field in the treatment region. Doses due to photons and neutrons were both measured by using radiochromic films and superheated bubble detectors, respectively, and simulated with Monte Carlo codes.
Results: For a 10 cm
7 10 cm square photon field with accelerating potentials 6 MV, 10 MV and 15 MV, the neutron dose equivalent in phantom was measured and its values was 0.07 mGy/Gy (neutron dose equivalent / photon absorbed dose at isocentre), 0.99 mGy/Gy and 2.22 mGy/Gy, respectively.
For a 18 MV treatment, simulations and measurements quantified the thermal neutron field in the treatment zone in 1.55
7 107 cm 122 Gy 121. Assuming a BNCT- standard 10B concentration in tumour tissue, the calculated additional BNCT dose at 4 cm depth in phantom would be 1.5 mGy-eq/Gy. This ratio would reach 43 mGy- eq/Gy for an intensity modulated radiotherapy treatment (IMRT).
When a specifically designed compact neutron photo-converter-moderator assembly is applied to the LINAC to enhance the thermal neutron field, the photon field is modified. Particularly, a 15 MV photon field produces a dose profile very similar to that would be produced by a 6 MV field in absence of the photo-converter-moderator assembly. As far as the thermal neutron field is concerned, more thermal neutrons are present, and thermal neutrons per photon increase of a factor 3 to 12 according to the depth in phantom and to different photoconverter geometries. By contrast, the photo-converter-moderator assembly was found to reduce fast neutrons of a factor 16 in the direction of the incident beam.
Conclusions: The parasitic thermal neutron component during conventional high- energy radiotherapy could be exploited to produce additional therapeutic doses if the 10B-carrier was administered to the patient. This radiosensitization effect could be increased by modifying the treatment field by using the specifically designed neutron photo-converter-moderator assembly
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Realization of radiobiological in vitro cell experiments at conventional X-ray tubes and unconventional radiation sources
[no abstract available
Irradiation of luminescence dosimeters in pulsed mixed radiation fields
UHDpulse - Metrology for Advanced Radiotherapy using beams with Ultra-High
Pulse Dose Rates is a European project aimed at developing novel dosimetry
standards, as well as improving existing ones, for FLASH radiotherapy, very
high energy electrons radiotherapy, and laser-driven medical accelerators.
Within the scope of this project, Thermoluminescence (TL) and Optically
Stimulated Luminescence (OSL) detectors are used to measure stray radiation
fields. Experiments performed with conventional pulsed particle-beams allow to
characterize the dosimeters in known and controllable radiation fields. In
turn, this allows to develop models and predict their behavior in complex
radiation fields, such as those at laser-driven and FLASH facilities. TL and
OSL detectors were irradiated at the Microtron MT25 electron accelerator in
Prague, Czech Republic. GAFChromicTM films and plastic nuclear track detectors
were used to study the beam profile and the neutron background respectively.
The responses of the different detector to the pulsed mixed radiation fields of
the Microtron MT25 are compared among each other and presented in this paper
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