The Performance of LiF:Mg-Ti for Proton Dosimetry within the Framework of the MoVe IT Project

Vittoria D’Avino,Giuseppe La Verde,Mariagabriella Pugliese,Stefano Lorentini,Francesco Tommasino

doi:10.3390/app11178263

Abstract

Proton therapy represents a technologically advanced method for delivery of radiation treatments to tumors. The determination of the biological effectiveness is one of the objectives of the MoVe IT (Modeling and Verification for Ion Beam Treatment Planning) project of the National Institute for Nuclear Physics (INFN) CSN5. The aim of the present work, which is part of the project, was to evaluate the performance of the thermoluminescent dosimeters (TLDs-100) for dose verification in the proton beam line. Four irradiation experiments were performed in the experimental room at the Trento Proton Therapy Center, where a 150 MeV monoenergetic proton beam is available. A total of 80 TLDs were used. The TLDs were arranged in one or two rows and accommodated in a specially designed water-equivalent phantom. In the experimental setup, the beam enters orthogonally to the dosimeters and is distributed along the proton beam profile, while the irradiation delivers doses of 0.8 Gy or 1.5 Gy in the Bragg peak. For each irradiation stage, the depth–dose curve was determined by the TLD readings. The results showed the good performance of the TLDs-100, proving their reliability for dose recordings in future radiobiological experiments planned within the MoVe IT context.

Highlights

Proton beam therapy (PBT) represents the election therapy for the treatment of many solid tumors [1,2]
The results indicate that for all commonly used materials, the sensitivity (TL response or absorbed dose) decreases with increasing linear energy transfer (LET); it has been demonstrated that the sensitivity of the high temperature peak for TLD-100 in the proton beam is stable, allowing the accurate determination of doses to within ±4.0% [30]
This study reports the results of several exploratory tests of physical dosimetry along the proton beam profile to verify the performance of TLDs for radiobiological dosimetry

Summary

Introduction

Proton beam therapy (PBT) represents the election therapy for the treatment of many solid tumors [1,2]. Charged particles (protons or ions) show physical properties that give a more localized energy deposition with reference to conventional MV X-ray therapy. PBT treatment plans manage to maximize the tumor control probability while minimizing the damage to surrounding healthy tissues. The theoretical advantage over photon radiation lies within the depth–dose profile, referred to as the Bragg curve, culminating with a sharp decrease beyond the so-called Bragg peak, especially for protons. In order to account for the difference in biological response between high linear energy transfer (LET) radiation and low LET radiation, the relative biological effectiveness (RBE) parameter was introduced. RBE is defined as the ratio of the absorbed dose of a usually low LET reference radiation

Methods

Results

Conclusion