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SU‐GG‐T‐291: Evaluation of Two Formulations of Commercial Water‐Equivalent Plastic to Establish Suitability for Dosimetry of the ZEISS Intrabeam® 50 KVp X‐Ray Source
Author(s) -
Dorgu A,
Pavord D,
Gong J,
Sherouse G,
Kriminski S
Publication year - 2010
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 - 10.1118/1.3468685
Subject(s) - dosimetry , water equivalent , ionization chamber , imaging phantom , nuclear medicine , brachytherapy , materials science , x ray , equivalent dose , beam energy , physics , beam (structure) , optics , ion , medicine , ionization , quantum mechanics , meteorology , snow , radiation therapy
Purpose: The ZEISS Intrabeam® is a 50 kVp x‐ray source intended for interstitial brachytherapy. The purpose of this investigation is to establish suitability of two formulations of commercial water‐equivalent plastic for dosimetry measurements for this device. Method and Materials: Plastic Water® (CIRS, Norfolk, VA) is a water‐equivalent resin material available in two formulations optimized for low energy dosimetry: LR l(5keV to 8MeV) and DT (50keV to 25MeV). The bare x‐ray source with no applicator attachment was positioned in the center of a 30×30×30 cm volume of pure water with two Exradin A1SL ion chambers (Standard Imaging, Middleton, WI) held symmetrically 4 cm directly lateral of the nominal target position, one on either side. Without otherwise changing the geometry three sets of measurements were made for each material by interposing 0, 1 and 2 cm respectively of material (replacing some of the water) between the source and chamber on one side only. The chamber on the other side served as a constancy reference. Results: Both the Plastic water® LR and DT formulations yielded results which differed from water alone by less that 2%. LR measurements ranged from 1.5% to 0.4% corresponding to 1cm and 2cm width (of phantom material), while DT ranged from 0.5% to 1.5% respectively. Conclusion: Both LR & DT formulations of Plastic Water® appear to be suitable as water‐equivalent media for dosimetry of the Intrabeam® 50kVp beam.