Dosimetry for New Radiation Therapy Approaches Using High Energy Electron Accelerators

Karolina Kokurewicz,Anna Subiel,Ralf-Peter Kapsch,Enrico Brunetti,Dino A Jaroszynski,Thomas Hackel,Rafael Kranzer,Markus Meier,Andreas Schüller

doi:10.3389/fphy.2020.568302

Abstract

We have performed dosimetry studies using electron beams with energies up to 50 MeV, which exceed current clinical energy ranges and approaches the bottom end of the very high energy electron (VHEE) range. 50 MeV electron beams can reach deep-seated tumours. In contrast to photon beams, electron beams can be generated with ultra-high dose rates by linear accelerators, which could enable FLASH radiotherapy of deep-seated tumours. The response of radiochromic film and alanine is compared with dose measurements using an ionisation chamber. Energy dependence is not observed within the measurement uncertainty in the investigated energy range from 15 MeV to 50 MeV.

Highlights

Radiotherapy (RT) is a cost-effective method of treating cancer, which alone or in combination with other cancer treatments contributes toward approximately 50% of cancer survivals [1,2,3]
FLASH radiotherapy is a promising treatment modality [4,5,6,7,8], which relies on delivery of therapeutic doses in less than a second (e.g., 90 ms [7]) at ultra-high dose rates (>40 Gy/s [4]), which are orders of magnitude higher than currently used in conventional radiotherapy
The data points are fitted to the analytical function given in Eq 6

Summary

Introduction

Radiotherapy (RT) is a cost-effective method of treating cancer, which alone or in combination with other cancer treatments contributes toward approximately 50% of cancer survivals [1,2,3]. Modified clinical linear accelerators can deliver electron beams with ultra-high dose rates, the limited penetration depth of the clinical energy range (4–22 MeV) remains an obstacle in FLASH RT clinical trials. The percentage depth dose (PDD) profile for 15 MeV electrons, shown in Figure 1 as blue curve, indicates that clinical electron beams cannot reach tumors deeper than 10 cm. This limits FLASH RT with electrons to preclinical studies using small animals such as mice or cats [3, 9, 11] as well as human patients with superficial tumors [7] and indications for intraoperative radiotherapy (IORT) [10]

Methods

Results

Conclusion