In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pelletsexposed to two different clinical proton beams employed for radiotherapy is performed. One beam ischaracterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line).Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue.We investigated how collimators with different sizes and shape used to conform the dose to the plannedtarget volume influence the delivered dose. For this purpose we performed measurements with varyingthe collimator size (Output Factor) and the results were compared with those obtained with other dosimetrictechniques (such as Markus chamber and diode detector). This analysis showed that the dosimeterresponse is independent of collimator diameter if this is larger than or equal to 10 mm. The other beam ischaracterized by an active spot-scanning technique, the Gantry1 beam line (maximum energy 230 MeV),and is used to treat deep-seated tumors. The dose linearity of alanine response in the clinical dose rangewas tested and the alanine dose response at selected locations in depth was measured and comparedwith the TPS planned dose in a quasi-clinical scenario. The alanine response was found to be linear inthe dose in the clinical explored range (from 10 to 70 Gy). Furthermore, a depth dose profile in aquasi-clinical scenario was measured and compared to the dose computed by the Treatment PlanningSystem PSIPLAN. The comparison of calibrated proton alanine measurements and TPS dose shows a differenceunder 1% in the SOBP and a ‘‘quenching” effect up to 4% in the distal part of SOBP. The positivedosimetric characteristics of the alanine pellets confirm the feasibility to use these detectors for ‘‘in vivo”dosimetry in clinical proton beams.
|Numero di pagine||7|
|Rivista||NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION B, BEAM INTERACTIONS WITH MATERIALS AND ATOMS|
|Stato di pubblicazione||Published - 2016|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
Longo, A., Carlino, A., Marrale, M., Gallo, S., Marrale, M., Lomax, T., Carlino, A., Longo, A., Panzeca, S., Gallo, S., Hrbacek, J., Bolsi, A., & Panzeca, S. (2016). EPR/alanine dosimetry for two therapeutic proton beams. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION B, BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 368, 96-102.