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Three years after the first edition, we are happy to invite you to the 2nd Workshop “Trento Proton Beam Line Facility”. While the first edition was organized remotely in 2020 due to pandemic restrictions, we are now planning for a two-days meeting in Trento.
The workshop will be dedicated to past and current Users of the Trento facility, which is part of the Trento Proton Therapy Center (APSS, Azienda Provinciale per i Servizi Sanitari), and aims at:
The meeting is scheduled for June 17-18th 2024. Registration and abstract submission is now open. Further information can be found in the dedicated sections (left menu).
This study presents the outcomes of combined radiobiological-microdosimetric experiments conducted in the same selected positions along the profile of a Spread-Out Bragg Peak (SOBP). The aim was to obtain the necessary parameters for a novel microdosimetric model for computing photon isoeffective doses in proton therapy [1-5]. This model, named Continuous Microdosimetric Photon Isoeffective Dose Model, depends on the first 3 moments of the lineal energy of microdosimetric spectra. In addition, these quantities are closely linked to Modified Linear Quadratic survival parameters that will be obtained from radiobiological experiments.
In this context, microdosimetric spectra measurements were conducted using two different Mini-TEPC microdosimeters in collaboration with Valeria Conte et al. (INFN). The sensitive volume of each microdosimeter was positioned at five predetermined measuring positions within solid water blocks, employing SOBP produced by a 148 MeV proton beam in the experimental room of the Trento Proton Therapy Centre.
Cell survival curves were generated at the same five designated positions, employing the same experimental setup used in microdosimetric experiments. These curves were constructed using doses of 0.5, 1.5, 3.5, 6, and 8 Gy, considering two different cell lines, JHU-11 and H460.
Radiobiological experiments involved the irradiation of two cell culture flasks at the same time positioned in the same way as the sensitive volume of the microdosimeter, so that they were exposed to a similar radiation field.
The model depends also on radiobiological parameters for a reference photon radiation. Survival curve for both cell lines were obtained using photons from the Xstrahl RS225 X-ray research irradiator available at TIFPA, considering the following doses: 0.5, 1.5, 3.5, 6, and 8 Gy.
[1] González et al. The photon isoeffective dose in BNCT. Radiat.Res.178.6(2012):609-621.
[2] González et al. Photon isoeffective dose for cancer treatment with mixed field radiation based on dose–response assessment from human and an animal model: clinical application to BNCT for head & neck cancer. Phys.Med.Biol.62.20(2017):7938.
[3] Perotti Bernardini et al. Comparison of Photon Isoeffective Dose Models Based on In Vitro and In Vivo Radiobiological Experiments for Head & Neck Cancer Treated with BNCT. Radiat.Res.(2022):134-144.
[4] Valeriano et al. (2023). A new formalism in hadron therapy for dose calculations in photon equivalent units. PTCOG Conference.
[5] Postuma et al. Using the photon isoeffective dose formalism to compare and combine BNCT and CIRT in a head & neck tumour. Sci.Rep.14.1(2024):418.
Minibeam irradiation is seen as a new frontier for exploiting the advantages of proton beams, as well as other types of radiation, towards increasing the therapeutic ratio on clinical treatments. In this context a novel INFN project has been recently launched called MIRO - Minibeam Radiation, dedicated to the investigation of beam design and radiobiological effectiveness of electron and proton minibeam irradiations. The first part of this project carried on at the Trento proton beam Laboratory (TEPBL) was the setup of a dedicated line for irradiation through a specific collimator, which, being able to serve both for protons (70 MeV) and electrons could allow a link between the local investigations and those performed with electrons in Pisa. This first setup was firstly characterised by extensive simulations and then used for experimental measurements through EBT films. The agreement between simulation and measurements was very promising and it was possible realised a peak to valley dose ratio (PVDR) uin the setup, larger of 3.5, uo to 5 mm depth after the collimator, thus allowing in principle irradiation of biological samples in the range relevant to mini beam radiobiology research. Further design of more opimized collimators is also proposed, through dedicated simulations.