Michele Togno (Switzerland)
Paul Scherrer Institute
Center for Proton Therapy
Michele Togno obtained his MSc at the university Politecnico di Milano, Italy, followed by a PhD in Physics at the Technische Universitaet Muenchen, Germany. He worked as R&D physicist for IBA Dosimetry GmbH until 2018, when he moved to Switzerland to join the Center for Proton Therapy (CPT) of Paul Scherrer Institut. In his current position, he is responsible and coordinator of the dosimetry activities at CPT, and participates in the development, clinical integration, commissioning and maintenance of the dosimetry equipment of the center. He is active member of the work party WP2 (Dose assessment, quality assurance, dummy runs, technology inventory) of the European Particle Therapy Network – a task force of ESTRO. Recently, his research work focused on the investigation of dosimeters response in ultra-high dose rate (FLASH) proton therapy beams.

Moderator of 1 Session

 Online Program
FLASH in Pre-Clinical and Clinical Settings

FLASH in Pre-Clinical and Clinical Settings : QA and Dosimetry - (Oral presentations)

Session Type
FLASH in Pre-Clinical and Clinical Settings
Date
30.11.2022
Session Time
11:00 - 12:00
Room
Hall 131-132
Chair(s)

Presenter of 1 Presentation

 Online Program

CHARACTERIZATION OF A PROTON IRRADIATION SETUP FOR IN VIVO PRE-CLINICAL FLASH EXPERIMENTS

Session Type
FLASH Modalities Track
Session Name
0410 - FLASH Modalities: Facilities and Radiation Protection - (Oral presentations) (ID 28)
Date
30.11.2022
Session Time
17:40 - 18:40
Room
Hall 113-114
Presenter
Lecture Time
17:47 - 17:54

Abstract

Background and Aims

To present the optimization of an irradiation setup suitable to investigate the FLASH effect in high-energy proton beams, and to characterize the dosimetric properties (absolute and relative dose) of the irradiation beam in view of in vivo pre-clinical experiments.

Methods

An experimental setup consisting of a scattered single pencil beam and a copper collimator (17 mm aperture) was optimized (in TOPAS simulations and measurements) to achieve uniform dose/dose rate coverage after the applicator. Absolute dosimetry was performed with EBT3 films and a PTW microDiamond cross-calibrated in a proton beam (PSI), and with passive dosimeters (TLD, alanine) from IRA (CHUV) calibrated in a Co-60 reference beam. A scintillator screen was also used for relative dose measurements.

Results

A robust and reproducible irradiation setup capable to deliver protons at ultra-high dose rates was implemented and characterized at PSI Gantry 1. The thickness of the collimator, as well as its distance from the irradiation nozzle, were optimized to achieve dose rates > 100 Gy/s. Indeed, the dose rate at the exit of the applicator is increased (> 25%) by scattered protons compared to the dose rate in the un-collimated beam. The average dose measured by the PSI’s and IRA’s detectors was in agreement within ± 2%. In the optimized scenario, the surface lateral dose uniformity was found to be within ± 5% over the collimator’s aperture.

Conclusions

A single pencil proton beam can be scattered and collimated to achieve ultra-high dose rates in a 17 mm large uniform field. Dosimetric agreement could be established in a controlled bilateral comparison with active and passive detectors. This study serves as basis for a larger investigation which aims at comparing the FLASH effect in different irradiation beams with in vivo biological models.

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