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Poster — Thur Eve — 44: Short Term Development Effects of Gafchromic EBT2 Film
Author(s) -
Lamey M,
Field C,
McKenzie M,
Fallone BG
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 - 10.1118/1.3476149
Subject(s) - tomotherapy , scanner , dosimetry , materials science , imaging phantom , irradiation , calibration , nuclear medicine , optics , medicine , physics , radiation therapy , quantum mechanics , nuclear physics
Gafchromic external beam therapy (EBT)2 is used in our clinic to verify the delivery of Tomotherapy patient plans. We have investigated the short term development effects of Gafchromic film up to 16 hours after irradiation. The importance of the scan position of the film along the active region of a Vidar Pro Dosimetry scanner is also studied. Materials/Methods: An EBT2 film is placed between two halves of a cylindrical phantom. A calibration plan which delivers dose in 13 predefined regions on the film is delivered on a Tomotherapy Hi‐ART 2 (Tomotherapy Inc., Madison WI) system. A point dose is taken within the phantom and used to determine the film irradiation response. The film was scanned using a Vidar Pro Dosimetry Advantage (Vidar, Herndon, VA, USA) scanner. The film was scanned after irradiation at times ranging from 5 minutes to 16 hours. The importance of the film position along the scanner active region was investigated by scanning the film under two conditions: at the edge of the scanner and at the middle of the scanner. Results/Discussion: One hour after irradiation the film had developed to 98.5 % of the measured OD at 16 hours, while after 2 hours, the film had developed to approximately 99 % of the measured OD at 16 hours. Specific to our calibration file setup, we measured a difference of 4.7 % in the 54 cGy region. This large difference could be important when using film to determine the acceptance of patient plans.