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RBE estimation of proton radiation fields using a Δ E − E telescope
Author(s) -
Wroe Andrew,
Schulte Reinhard,
Fazzi Alberto,
Pola Andrea,
Agosteo Stefano,
Rosenfeld Anatoly
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3215927
Subject(s) - sobp , physics , bragg peak , telescope , proton therapy , imaging phantom , relative biological effectiveness , proton , detector , dosimetry , optics , computational physics , nuclear medicine , radiation , nuclear physics , medicine
A new monolithic silicon Δ E − E telescope was evaluated in unmodulated and modulated 100 MeV proton beams used for hadron therapy. Compared to a classical microdosimetry detector, which provides one‐dimensional information on lineal energy of charged particles, this detector system provides two‐dimensional information on lineal energy and particle energy based on energy depositions, collected in coincidence, within the Δ E and E stages of the detector. The authors investigated the possibility to use the information obtained with the Δ E − E telescope to determine the relative biological effectiveness (RBE) at defined locations within the proton Bragg peak and spread‐out Bragg peak (SOBP). An RBE matrix based on the established in vitro V79 cell survival data was developed to link the output of the device directly to RBE ( α ) , the RBE in the low‐dose limit, at various depths in a homogeneous polystyrene phantom. In the SOBP of a 100 MeV proton beam, the RBE ( α )increased from 4.04 proximal to the SOBP to a maximum value of 5.4 at the distal edge. The Δ E − E telescope, with its high spatial resolution, has potential applications to biologically weighted hadron treatment planning as it provides a compact and portable means for estimating the RBE in rapidly changing hadron radiation fields within phantoms.