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Create a Free AccountFLASH technology and dosimetry: a selection of papers presented at the conference "FRPT2021 - FLASH Radiotherapy & Particle Therapy
Out-of-field measurements and simulations of a proton pencil beam in a wide range of dose rates using a Timepix3 detector: Dose rate, flux and LET
Heavy-charged particle (protons and heavier ions) radiation therapy (RT) is an advanced and innovative technique used successfully to treat various types of tumors. Heavy charged particles have a finite range and deposit most of the dose at the end of the range in the Bragg peak (BP), which can reduce the dose deposition in healthy tissue as compared to the most advanced technology in conventional photon RT. FLASH treatment is a recent concept introduced in the field of radiotherapy that showed a reduction of adverse effects to the surrounding healthy tissue but the same tumor control after ultra-high dose rate (UHDR) irradiation compared to conventional dose rate RT [1–3].A novel electron source for a compact x-ray tube for microbeam radiotherapy with very high dose rates
Microbeam radiotherapy (MRT) is a novel concept in radiation oncology with arrays of alternating micrometer-wide high-dose peaks and low-dose valleys. Preclinical experiments have shown a lower normal tissue toxicity for MRT with similar tumor control rates compared to conventional radiotherapy. A promising candidate for the demanded compact radiation source is the line-focus x-ray tube. Here, we present the setup of a prototype for an electron accelerator being able to provide a suitable x-ray beam for the tube.Ion recombination correction factors and detector comparison in a very-high dose rate proton scanning beam
Radiotherapy is a curative treatment for a large variety of cancers and is one of the key components of effective cancer treatment, comprising 50 % to 60 % of cancer treatments. It operates on a thin line between maximizing the eradication of tumour cells while minimizing the damage to nearby healthy tissues. Already observed in 1959 by Dewey and Boag [1], the effect of large doses delivered in a short time was recently brought to the spotlight by Favaudon et al. [2] who used an electron accelerator to produce mean dose rate electron beams greater than 40 Gy/s, and observed that FLASH-irradiated mice did not exhibit pneumonitis and lung fibrosis, unlike conventional dose rate (≤0.03 Gy/s) irradiated mice, while retaining tumour control – FLASH effect.FLASH l a b @PITZ : New R&D platform with unique capabilities for electron FLASH and VHEE radiation therapy and radiation biology under preparation at PITZ
The classical approach of radiation therapy for cancer care relies largely on the rationale that cancer cells are less efficient in repairing DNA damages than normal cells – an effect that is also dependent on the tumor microenvironment [1]. However, radiation can damage normal tissue surrounding the treated tumor and radioresistance occurs [2–4] that limits the applied treatment dose and causes cancer relapse, respectively. The treatment of radiation-resistant and metastatic cancers is nowadays a major challenge.Perspectives in linear accelerator for FLASH VHEE: Study of a compact C-band system
In order to translate the FLASH effect in clinical use and to treat deep tumors, Very High Electron Energy irradiations could represent a valid technique. Here, we address the main issues in the design of a VHEE FLASH machine. We present preliminary results for a compact C-band system aiming to reach a high accelerating gradient and high current necessary to deliver a Ultra High Dose Rate with a beam pulse duration of 3 μ s .Reduction of recombination effects in large plane parallel beam monitors for FLASH radiotherapy with scanned ion beams
Radiotherapy escalating dose rates above 50Gys−1, might offer a great potential in treating tumours while further sparing healthy tissue. However, these ultra-high intensities of FLASH-RT lead to new challenges with regard to dosimetry and beam monitoring. FLASH experiments at HIT (Heidelberg Ion Beam Therapy Center) and at GSI (GSI Helmholtz Centre for Heavy Ion Research) have shown a significant loss of signal in the beam monitoring system due to recombination effects. To enable accurate beam monitoring, this work investigates the recombination loss of different fill gases in the plane parallel ionisation chambers (ICs).Ultra-high dose rate dosimetry for pre-clinical experiments with mm-small proton fields
Radiation therapy with ultra-high dose rates (UHDR) has gained momentum in recent years not only because of the beneficial impact on treatments’ duration, but particularly for the promising reduction of adverse side effects to healthy tissue as observed in in-vivo experiments [1–4]. This so-called FLASH effect has been mainly investigated in electron beams [5,6], but pre-clinical studies in X-ray photons [7] as well as in proton and heavy-ion beams [8–10] are increasing in number. Whilst the biological mechanisms behind the FLASH effect are not yet fully understood, and more experiments are required to confirm the protecting effect in proton beams [11], several technical and metrological challenges arise in this unconventional irradiation modality [12].Charge collection efficiency, underlying recombination mechanisms, and the role of electrode distance of vented ionization chambers under ultra-high dose-per-pulse conditions
Currently, ultra-high dose rates (UHDR) are used to study the so-called FLASH effect. It was found that irradiation with UHDR greater than 40 Gy/s can lead to sparing of healthy tissue while maintaining tumor control. This sparing effect has been discussed and reviewed recently in the literature [1–5]. Most studies of this biological effect have been performed with dedicated electron linear accelerators or modified medical accelerators with pulsed beams [6–11]. The dose-per-pulse (DPP) is in the range of 0.6 to 10 Gy that are orders of magnitude higher than in conventional radiotherapy.A new calculation method for the free electron fraction of an ionization chamber in the ultra-high-dose-per-pulse regimen
The Flash Effect [1,2], produced by ultra-high dose per pulse (UHDP) beams, is a radiobiological effect obtained by delivering the entire therapeutic dose in less than 100 ms. This phenomenon allows to drastically reduce the side effects on healthy tissues while maintaining the same therapeutic efficacy on tumour tissue, resulting in a widened therapeutic window.Numerical modeling of air-vented parallel plate ionization chambers for ultra-high dose rate applications
Air-vented ionization chambers have been the secondary standard for radiation dosimetry since the origins of radiation metrology. However, the feasibility of their use in ultra-high dose rate pulsed beams has been a matter of discussion, as large losses are caused by ion recombinations and no suitable theoretical model is available for their correction. The theories developed by Boag and his contemporaries since the 1950s, which have provided the standard ion recombination correction factor in clinical dosimetry, do not provide an accurate description when used under the limit conditions of ultra-high dose rates (UHDRs).Point scintillator dosimetry in ultra-high dose rate electron “FLASH” radiation therapy: A first characterization
FLASH radiation therapy is a novel technique combining ultra-high dose rates (UHDR) with very short treatment times to strongly decrease normal tissue toxicity while preserving the anti-tumoral effect. However, the radiobiological mechanisms and exact conditions for obtaining the FLASH-effect are still under investigation. There are strong indications that parameters defining the beam structure, such as dose per pulse, instantaneous dose rate and pulse repetition frequency (PRF) are of importance.A new solution for UHDP and UHDR (Flash) measurements: Theory and conceptual design of ALLS chamber
The FLASH effect [1,2] is a radiobiological effect obtained by delivering the entire therapeutic dose in less than 100 ms, thus allowing to drastically reduce the side effects for healthy tissues, still maintaining the same therapeutic efficacy on the tumor. This leads to a broadening of the therapeutic window.Monte Carlo modelling of pixel clusters in Timepix detectors using the MCNP code
In the planning and delivery of external radiation therapy with ionizing radiation (e.g., photons, electrons, protons), i.e. “radiotherapy”, the main focus placed on accurate delivery of the dose to the target volume and minimization of the dose to the surrounding critical organs. Currently, another topic of great interest in radiotherapy is the dosimetry outside the primary particle beam, or out-of-field dosimetry [1].
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