Characterization of the Exradin A26 microchamber for small field dosimetry. (September 2016)

• Record Type: Journal Article
• Authors: Pasquino, M.; Cutaia, C.; Radici, L.; Gino, E.; Stasi, M.
• Is Part Of: Physica medica. Volume 32(2016)Supplement 3
• Page Start: 201
• Publication Date: 2016-09
• Subjects: Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2016.07.682
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract : Introduction: In modern radiation therapy accurate dosimetry within small photon fields is a challenge. The aim of the study is to investigate the main dosimetric characteristics of a new small field detector. Material and methods: An Exradin A26 microionization chamber was tested. Short term stability, dose linearity, polarity effect, angular dependence and energy dependence were evaluated for field sizes up to 10 × 10 cm 2 . Results were compared with those obtained with an Exradin A1SL IC. PDD curves, OAR profiles and OF values were measured for different field sizes. The results were compared with those obtained with an IC and an EDGE diode. Results: A26 IC readings showed a 0.2% and 0.1% relative standard deviation for 3 × 3 and 10 × 10 cm 2 fields, respectively. Dose response was linear to within 0.5%. The microchamber showed the maximum variation from the reference condition at the lowest dose rate. The polarity effect is within 0.5% for field size greater than 2 × 2 cm 2 ; for field size less than 2 × 2 cm 2 the effect increases, still remaining within 1%. No energy and angular dependence were observed. A26 IC PDD measurements agreed with those obtained with the EDGE diode. FWHM values show a better agreement with the EDGE diode values than A1SL. The penumbra values were greater than those obtained with the EDGE diode. Of values showed a good agreement with EDGE diode ones. Conclusions: The study confirms A26 IC as a reference detector for PDD and OAR measurements.