Authors: Y J Chang C H Chen B T Hsieh
Publish Date: 2014/06/08
Volume: 301, Issue: 3, Pages: 765-780
Abstract
In this study the detailed characteristics including spatial uniformity dose distributions interbatch variability reproducibility and longterm temporal stability of Nisopropylacrylamide NIPAM polymer gel dosimeter were investigated A commercial 10x fast optical computed tomography scanner OCTOPUSTM10× MGS Research Inc Madison CT USA was used to measure NIPAM polymer gel dosimeter A cylindrical NIPAM gel phantom that measured 10 cm × 10 cm was irradiated via a singlefield treatment plan with a field size of 4 cm × 4 cm The maximum standard deviation of spatial uniformity for NIPAM gel was less than 029 The average standard deviation among the three batches of gel dosimeters was less than 1 The gamma pass rate could reach as high as 9676 when a 3 dose difference and a 3 mm dosetoagreement criteria were used The longterm measurement of irradiated NIPAM gel dosimeter indicated that the dose maps attained a gradually stable value 15 h postirradiation and remained stable until 72 h postirradiation The gamma pass rate could achieve a maximum value between 24 and 72 h postirradiation The edge enhancement effect that occurred around the irradiated region was observed 72 h postirradiation Thus the results from this study suggest that NIPAM gel dosimeter should be measured approximately 24 h postirradiation to reduce the occurrence of the edge enhancement effect
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