Abstract：
PURPOSE:To describe an efficient method for verifying the size and centering of the radiation field from the Cyberknife IRIS variable collimator with sub-millimeter accuracy using a general purpose commercially available diode array. METHODS:We present a technique using a conventional diode array (Sun Nuclear Profiler) with the array at an extended distance of 320 cm. The projection of the 4 mm diode spacing back to the 80 cm field definition distance gives an effective spacing of 1 mm, sufficient to confirm proper operation of the IRIS. We describe the data acquisition process and present data comparing the Profiler measurements to scanned measurements for both profile and FWHM analysis and reproducibility of the technique over repeated measurements. RESULTS:Average difference between original water scanner measurements and diode array measurements over the 12 aperture sizes) from 5 mm to 60 mm) were - 0.14 mm (range 0.03 mm to 0.83 mm). Reproducibility and centering measurements had a similar range of accuracy. CONCLUSIONS:A general purpose commercially available diode array can be used to quickly and accurately characterize the field size and centering of the Cyberknife IRIS variable collimator system with sub-millimeter accuracy subsequent to service, software recalibration, software upgrades or associated with routine QA. This technique avoids the time consuming and cumbersome water tank scanning with a diode and the difficulties associated with image based measurements (CR or radiochromic film) that require time consuming and careful calibration and choice of threshold values.
journal_name
Med Physjournal_title
Medical physicsauthors
Gibbs G,White G,Bulz Gdoi
10.1118/1.4735220subject
Has Abstractpub_date
2012-06-01 00:00:00pages
3740issue
6Part12eissn
0094-2405issn
2473-4209journal_volume
39pub_type
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