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Vienna, Austria

ESTRO 2023

Session Item

Sunday
May 14
10:30 - 11:30
Stolz 2
Advanced treatment planning with photons and particles
Cristina Garibaldi, Italy;
Gert Meijer, The Netherlands
Mini-Oral
Physics
Potential of Very High Energy Electron (FLASH) beams in pancreatic and head-and-neck treatments
Annalisa Muscato, Italy
MO-0477

Abstract

Potential of Very High Energy Electron (FLASH) beams in pancreatic and head-and-neck treatments
Authors:

Annalisa Muscato1, Lorenzo Arsini2,3, Lorenzo Campana4,5, Daniele Carlotti6,7, Angelica De Gregorio8,6, Francesca De Felice9, Cinzia Di Felice10, Marta Fischetti11,12, Michele Fiore7,13, Gaia Franciosini14,6, Michela Marafini14,15, Valerio Marè16, Ilaria Mattei17, Massimiliano Pacilio18, Vincenzo Patera8,19, Sara Ramella16,20, Angelo Schiavi19,8, Adalberto Sciubba14,19, Marco Schwarz21, Marco Toppi19, Giacomo Traini22, Antonio Trigilio8,6, Alessio Sarti8,19

1University La Sapienza of Rome, Department of Scienze e Biotecnologie medico-chirurgiche, Rome, Italy; 2University La Sapienza of Rome, Physics Department, Rome, Italy; 3INFN,Isituto Nazionale Fisica Nucleare, Section of Rome 1 , Rome, Italy; 4INFN, Istituto Nazionale Fisica Nucleare , Section of Rome 1 , Rome, Italy; 5University La Sapienza of Rome, Department of Scienze e Biotecnologie medico-chirurgiche, Rome , Italy; 6University La Sapienza of Rome, Physics Department , Rome, Italy; 7Fondazione Policlinico Universitario Campus-Bio Medico, Operative Research Unit of Radiation Oncology, Rome, Italy; 8INFN, Istituto Nazionale Fisica Nucleare, Section of Rome 1, Rome, Italy; 9Azienda Ospedaliero-Universitaria Policlinico Umberto I, Department of Radiological,Oncological and Pathological Sciences, Rome, Italy; 10Azienda Ospedaliero-Universitaria Policlinico Umberto I, Unità di Fisica Sanitaria , Rome, Italy; 11University La Sapienza of Rome, Department of Scienze di Base e Applicate per l'Ingegneria, Rome, Italy; 12INFN,Istituto Nazionale Fisica Nucleare, Section of Rome 1 , Rome, Italy; 13University Campus-Bio Medico of Rome, Research Unit of Radiation Oncology, Department of Medicine and Surgery , Rome, Italy; 14INFN, Istituto Nazionale Fisica Nucleare, Section of Rome 1 , Rome, Italy; 15Museo Storico della Fisica e Centro Studi e Ricerche “E.Fermi”, -, Rome, Italy; 16Fondazione Policlinico Universitatio Campus-Bio Medico, Operative Research Unit of Radiation Oncology, Rome, Italy; 17INFN, Istituto Nazionale Fisica Nucleare, Section of Milan , Milan, Italy; 18Azienda Ospedaliero-Universitaria Policlinico Umberto I, Unità di Fisica Sanitaria, Rome, Italy; 19University La Sapienza of Rome, Department of Scienze di Base e Applicate per l’Ingegneria, Rome, Italy; 20Università Campus Bio-Medico of Rome, Research Unit of Radiation Oncology, Department of Medicine and Surgery, Rome, Italy; 21Fred Hutch Cancer Center, Radiation Oncology Department , Seattle, USA; 22INFN, Istituto Nazionale Fisica Nucleare , Section of Rome 1, Rome, Italy

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Purpose or Objective

External beam radiotherapy is currently performed with either photons (RT), protons (PT) or heavier ions like 12C. VHEE beams (100-200 MeV) for the treatment of deep seated tumors are now being considered as well due to the developments in the field of the C-band electron acceleration and FLASH radiotherapy. Compact accelerators with high gradients (~50 MeV/m) will provide ultra-high dose rate (UHDR) beams (>40 Gy/s) suitable for clinical implementation.  We investigated how VHEE could be used in the treatments of deep seated tumors, working on head and neck and pancreatic cancer cases, and compared them with conventional RT or PT.

Material and Methods

We implemented and developed a VHEE treatment plan using an accurate Monte Carlo simulation of the electrons interaction with the patient tissues and included the FLASH effect modelling as a function of the absorbed dose. We studied in detail the feasibility of treating patients with VHEE with kinetic energies in the 70 – 130 MeV range. From the results obtained, based on a set of beam delivery parameters and reasonable assumptions on the conditions that have to be met to trigger the FLASH effect, we computed the absorbed dose rate taking into account a Flash Modifying Factor (FMF) accounting also for the dose rate dependence [1]. For calculating the latter, the Average Dose Rate (ADR) definition was used [2].

[1] doi: 10.1016/j.ijrobp.2022.05.038

[2]   doi:10.1002/mp.14456

Results

Even without assuming a dose modification factor due to FLASH, VHEE dose distributions are competitive with respect to PT and RT when it comes to both target coverage and organs at risk (OARs) sparing: in Fig 1 (right, solid line – pancreatic cancer) and Fig 2 (bottom right – head and neck district) FMF 1 was used.  FLASH effect helps the duodenum sparing in the case of pancreatic cancer in comparison with standard VMAT RT as shown in Fig 1 (right). Such results were obtained with a reasonable treatment hypofractionation (6 Gy/fr) and beam delivery strategy. The implemented thresholds on the dose and on the ADR to enable the FLASH sparing were 4 Gy and 40 Gy/s, respectively.  








Figure 1: DVH of a treatment of pancreatic cancer. (left) VMAT treatment delivered to the patient (right) VHEE treatment. Solid line implies FMF = 1. Results with FMF in the 0.6 – 0.9 range are shown by dashed and dotted lines.

Figure 2: treatment of a Meningioma. (left) proton treatment delivered to the patient. (centre) planning of a 7 fields IMRT treatment. (right) VHEE treatment performed using FMF = 1.


Conclusion

The results obtained without exploiting the FMF demonstrate the VHEE potential in treating deep seated tumors when compared with conventional EBRT both in the H&N and pancreatic pathologies. The impact of UHDR irradiation, both as function of absorbed dose and dose rate has been explored, showing interesting perspectives in the context of dose escalation approaches.