Presenter of 3 Presentations
Q&A
Advancing Treatment Planning Methods for FLASH
TREATMENT PLANNING TOOLS TO EVALUATE THE FEASIBILITY OF FLASH THERAPY WITH PROTONS
Abstract
Background and Aims
To exemplify the potential and limitations of two approaches to FLASH treatment planning with protons by testing them on two clinically realistic scenarios and different FLASH-specific parameters
Methods
We selected two planning approaches to be delivered with a cyclotron: 3D range modulator (3DRM) and transmission beams(TB). (See Table below for details on the beam delivery parameters.) We associated each planning technique with a disease site and a clinically applied hypofractionation protocol ( 3DRM - liver - 3x25Gy, TB - lung - 3x20Gy). We evaluated the resulting dose distributions for different beam currents (200nA and 800nA at isocentre), two dose rate definitions (dose-averaged dose rate (DADR) and a sliding time window), two minimum dose thresholds and two dose rate thresholds for the FLASH effect (4Gy and 8Gy, 40Gy/s and 100Gy/s, respectively).
Results
Both techniques achieved acceptable dose distributions with a limited number of fields (liver - 1 field, lung - 3 fields) for FLASH proton plans. All combinations of beam intensity, dose rate definition, dose and dose rate threshold we investigated were associated with some level of FLASH dose, suggesting that these disease sites and dosimetric protocols are reasonable candidates for FLASH proton therapy. The figure below shows an example of the results for 200nA and 4Gy and 40Gy/s thresholds.
Conclusions
Treatment planning studies are a useful tool to test candidate disease sites, protocols and planning techniques for proton FLASH. The next step will be to include additional combinations of beam production systems, planning techniques, and patient anatomies.
Author Of 4 Presentations
Advancing Treatment Planning Methods for FLASH
Q&A
TREATMENT PLANNING TOOLS TO EVALUATE THE FEASIBILITY OF FLASH THERAPY WITH PROTONS
Abstract
Background and Aims
To exemplify the potential and limitations of two approaches to FLASH treatment planning with protons by testing them on two clinically realistic scenarios and different FLASH-specific parameters
Methods
We selected two planning approaches to be delivered with a cyclotron: 3D range modulator (3DRM) and transmission beams(TB). (See Table below for details on the beam delivery parameters.) We associated each planning technique with a disease site and a clinically applied hypofractionation protocol ( 3DRM - liver - 3x25Gy, TB - lung - 3x20Gy). We evaluated the resulting dose distributions for different beam currents (200nA and 800nA at isocentre), two dose rate definitions (dose-averaged dose rate (DADR) and a sliding time window), two minimum dose thresholds and two dose rate thresholds for the FLASH effect (4Gy and 8Gy, 40Gy/s and 100Gy/s, respectively).
Results
Both techniques achieved acceptable dose distributions with a limited number of fields (liver - 1 field, lung - 3 fields) for FLASH proton plans. All combinations of beam intensity, dose rate definition, dose and dose rate threshold we investigated were associated with some level of FLASH dose, suggesting that these disease sites and dosimetric protocols are reasonable candidates for FLASH proton therapy. The figure below shows an example of the results for 200nA and 4Gy and 40Gy/s thresholds.
Conclusions
Treatment planning studies are a useful tool to test candidate disease sites, protocols and planning techniques for proton FLASH. The next step will be to include additional combinations of beam production systems, planning techniques, and patient anatomies.
ADVANCED DOSIMETRY AND BIOPHYSICAL MODELING FOR PRECLINICAL FLASH RADIOTHERAPY
Abstract
Background and Aims
Since the oxygen depletion hypothesis has been recently challenged, the setup of a new joint project dedicated to an alternative mechanistic explanation of the FLASH effect, presently submitted to the Italian Association for Cancer Research (AIRC), will be presented. Our approach is a bottom up analysis linking radiation chemical based radicals description and DNA damage modeling studies. This should enable us to predict the irradiation parameters of absolute dose, and dose rate for which the effect could be verified.
Methods
We will develop point-like and two dimensional optical based methods for FLASH real time dosimetry using Cerenkov and radioluminescence light.
In a second phase a multiscale mechanistic description of ultrahigh dose rate induced damage including oxygen interplay and reactive oxygen species production and reactions will be developed. Our approach is based on chemical track structure Monte Carlo simulations and dedicated extensions of analytical biophysical models.
Results
We expect to obtain:
-Real time dosimetric methods to monitor FLASH beams for cells and mice irradiations. The same methods can be also translated to monitor FLASH delivery to human patients.
-A refined mechanistic description of the FLASH effect starting from basic radiation chemistry concepts in a biological environment. We will also provide in vitro and in vivo validation tests using two types of FLASH beams.
Conclusions
This work will contribute to unraveling the basic biological mechanisms of the FLASH effect and, at the same time, it will provide accurate real time dosimetric tools not available at the moment.