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SU‐FF‐T‐266: Characterizing a Multi‐Axis Ion Chamber Array
Author(s) -
Simon T,
Fox C,
Simon W,
Li J,
Palta J,
Liu C
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 - 10.1118/1.3181743
Subject(s) - ionization chamber , linear particle accelerator , standard deviation , reproducibility , linearity , materials science , backscatter (email) , optics , detector , calibration , beam (structure) , physics , nuclear medicine , ion , mathematics , engineering , statistics , telecommunications , medicine , quantum mechanics , wireless , ionization
Purpose: To characterize a commercially available multi‐axis ion chamber array for use as a scanning water tank alternative. Method and Materials: The ion chamber array used in this study was the IC Profiler (Sun Nuclear Corporation: Melbourne, FL). We characterized four items of the array: reproducibility, dose linearity, backscatter response, and water tank agreement. Short and long term reproducibility's were established on a 60 Co teletherapy unit (Eldorado 6; Atomic Energy of Canada Limited: Mississauga, Canada). The remaining tests were conducted with a Synergy (Elekta: Crawley, UK) linear accelerator (LINAC) operated at a nominal photon energy of 6MV. Results: Over a short time period the array displayed a maximum standard deviation of 0.55% and a mean standard deviation of 0.15%; over a long time period the array displayed a maximum standard deviation of 1.80% and a mean standard deviation of 0.76%. The array was sensitive to startup characteristics of the LINAC when operating in pulsed mode; this affected the dose linearity relative to a Farmer chamber operating under the same geometry. This effect was not observed when the array was operated in continuous mode. Both the array's central axis detector and a Farmer chamber displayed a similar increase in measured signal with increasing backscatter. However, with increasing backscatter (up to 16.6 cm) the arrays in‐beam‐profile shape changed by less than 0.7% relative to a setup with no additional backscatter. The agreement between the array and a scanning water tank differed by less than 1% in the beam. Conclusion: The IC Profiler is a viable option for water tank ‘like’ measurements. The device provides a stable platform with good dose linearity, minimal backscatter response, and uniform profile measurements. Conflict of Interest: This work was supported in part by SBIR Contract No. HHSN261200522014C, the University of Florida, and Sun Nuclear Corporation